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Georgia Tech
1.
Sun, Yi.
The PH dependent mechanisms of peptide bond cleavage.
Degree: MS, Chemical and Biomolecular Engineering, 2019, Georgia Tech
URL: http://hdl.handle.net/1853/62365 
► The origin of life under prebiotic conditions has been an unsolved mystery for decades. Amino acids were available under prebiotic conditions, and different approaches of…
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▼ The origin of life under prebiotic conditions has been an unsolved mystery for decades. Amino acids were available under prebiotic conditions, and different approaches of amino acids condensation into proto-polypeptides have been well designed, giving rise to a prebiotic soup with various peptide sequences. The emergence of functional biopolymers involves not only polymerization into longer species, but also the selective process with some species being protected and enriched over time. In this project, we treated peptide bond cleavage as the driving force for the selection process, by reshuffling peptide sequences and thus increasing the rate of search through sequence space. As a result, understanding the reaction mechanisms and quantifying the degradation kinetics of various peptide species is necessary to design a prebiotically plausible system that can demonstrate chemical evolution. In this project, we conducted fundamental research studies to understand the impact of pH on the peptide degradation reaction kinetics and mechanisms. The degradation rate of the amide bonds in oligopeptides in aqueous solution is pH-dependent and is suggested to involve two distinct mechanism: direct hydrolysis (herein termed “scission”) and backbiting. While amide degradation was studied previously using various peptides, no systematic study has been reported addressing the separate rates of amide bond degradation over a wide pH range via these two mechanisms. In this study, the degradation kinetics of several short oligopeptides, specifically the glycine dimer, trimer, and cyclic dimer, as well as the alanine trimer, were measured at 95 °C over a range of pH conditions using 1H NMR. The rate constants were obtained by solving the differential equations based on mechanistic models and elucidate the favored reaction pathway under acidic, neutral, and basic pH conditions. The degradation rate of the glycine trimer is much faster than the dimer under the acidic and neutral pH conditions. The glycine dimer degradation rate is highest under acidic and basic conditions, while the glycine trimer degradation rate is highest under neutral pH conditions. The results suggest that while the glycine dimer undergoes ring opening purely through a scission reaction mechanism, the glycine trimer is degraded through both backbiting and scission reaction mechanisms. At an acidic pH of 3, both mechanisms are active, while at neutral pH backbiting is dominant. In contrast, at a basic pH of 10, scission dominates.
Advisors/Committee Members: Grover, Martha (advisor), Liotta, Charles (advisor), Grover, Martha (advisor), Liotta, Charles (advisor), Paravastu, Anant (committee member).
Subjects/Keywords: Non-enzymatic peptide cleavage; Peptide degradation kinetics
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APA (6th Edition):
Sun, Y. (2019). The PH dependent mechanisms of peptide bond cleavage. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62365
Chicago Manual of Style (16th Edition):
Sun, Yi. “The PH dependent mechanisms of peptide bond cleavage.” 2019. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/62365.
MLA Handbook (7th Edition):
Sun, Yi. “The PH dependent mechanisms of peptide bond cleavage.” 2019. Web. 18 Jan 2021.
Vancouver:
Sun Y. The PH dependent mechanisms of peptide bond cleavage. [Internet] [Masters thesis]. Georgia Tech; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/62365.
Council of Science Editors:
Sun Y. The PH dependent mechanisms of peptide bond cleavage. [Masters Thesis]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/62365
Georgia Tech
2.
Abu-Hakmeh, Khaldoon E.
Assessing the use of voting methods to improve Bayesian network structure learning.
Degree: MS, Chemical Engineering, 2012, Georgia Tech
URL: http://hdl.handle.net/1853/45826
► Structure inference in learning Bayesian networks remains an active interest in machine learning due to the breadth of its applications across numerous disciplines. As newer…
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▼ Structure inference in learning Bayesian networks remains an active interest in machine learning due to the breadth of its applications across numerous disciplines. As newer algorithms emerge to better handle the task of inferring network structures from observational data, network and experiment sizes heavily impact the performance of these algorithms. Specifically difficult is the task of accurately learning networks of large size under a limited number of observations, as often encountered in biological experiments. This study evaluates the performance of several leading structure learning algorithms on large networks. The selected algorithms then serve as a committee, which then votes on the final network structure. The result is a more selective final network, containing few false positives, with compromised ability to detect all network features.
Advisors/Committee Members: Styczynski, Mark (Committee Chair), Grover, Martha (Committee Member), Realff, Matthew (Committee Member).
Subjects/Keywords: Metabolomics; Bioinformatics; Machine learning; Bayesian networks; Artificial intelligence; Algorithms; Biology Data processing
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APA (6th Edition):
Abu-Hakmeh, K. E. (2012). Assessing the use of voting methods to improve Bayesian network structure learning. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/45826
Chicago Manual of Style (16th Edition):
Abu-Hakmeh, Khaldoon E. “Assessing the use of voting methods to improve Bayesian network structure learning.” 2012. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/45826.
MLA Handbook (7th Edition):
Abu-Hakmeh, Khaldoon E. “Assessing the use of voting methods to improve Bayesian network structure learning.” 2012. Web. 18 Jan 2021.
Vancouver:
Abu-Hakmeh KE. Assessing the use of voting methods to improve Bayesian network structure learning. [Internet] [Masters thesis]. Georgia Tech; 2012. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/45826.
Council of Science Editors:
Abu-Hakmeh KE. Assessing the use of voting methods to improve Bayesian network structure learning. [Masters Thesis]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/45826
Georgia Tech
3.
Garanger, Kevin.
Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations.
Degree: MS, Aerospace Engineering, 2018, Georgia Tech
URL: http://hdl.handle.net/1853/59957
► During the last decade, additive manufacturing (AM) has become increasingly popular for rapid prototyping, but has remained relatively marginal beyond the scope of prototyping when…
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▼ During the last decade, additive manufacturing (AM) has become increasingly popular for rapid prototyping, but has remained relatively marginal beyond the scope of prototyping when it comes to applications with tight tolerance specifications, such as in aerospace. Despite a strong desire to supplant many aerospace structures with printed builds, additive manufacturing has largely remained limited to prototyping, tooling, fixtures, and non-critical components. There are numerous fundamental challenges inherent to additive processing to be addressed before this promise is realized. One ubiquitous challenge across all AM motifs is to develop processing-property relationships through precise, in situ monitoring coupled with formal methods and feedback control. The goal of this thesis is to justify the relevance of closed-loop control in AM, and to pave the way for the creation of a general framework to formulate AM processes as control problems where feedback can be widely adopted. Two experiments of closed-loop control in additive manufacturing for the printing of specific parts are made. These experiments are a proof of concept that feedback control is feasible in AM even without precise physics models of the processes. From this point, a idea for the generalization of closed-loop control in AM is presented via the concept of semantics for AM files and the idea of adapting the local parameters of a printed object through topology optimization.
Advisors/Committee Members: Feron, Eric (advisor), Di Leo, Claudio (committee member), Grover, Martha (committee member), Rimoli, Julian (committee member).
Subjects/Keywords: Additive manufacturing; Feedback control; Closed-loop control; Semantics; 3D printing
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APA (6th Edition):
Garanger, K. (2018). Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59957
Chicago Manual of Style (16th Edition):
Garanger, Kevin. “Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations.” 2018. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/59957.
MLA Handbook (7th Edition):
Garanger, Kevin. “Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations.” 2018. Web. 18 Jan 2021.
Vancouver:
Garanger K. Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations. [Internet] [Masters thesis]. Georgia Tech; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/59957.
Council of Science Editors:
Garanger K. Introducing the foundations of a general framework for closed-loop control in additive manufacturing via in situ measurements and semantic annotations. [Masters Thesis]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/59957
Georgia Tech
4.
McBride, Michael A.
Solution processing via blending approaches to control self-assembly of conjugated polymers.
Degree: PhD, Chemical and Biomolecular Engineering, 2019, Georgia Tech
URL: http://hdl.handle.net/1853/62686
► Thematically, this work focuses on developing solution blending processes that result in the formation of interconnected polymer networks for enhanced electronic properties. This research follows…
(more)
▼ Thematically, this work focuses on developing solution blending processes that result in the formation of interconnected polymer networks for enhanced electronic properties. This research follows a bottom-up approach to develop process-structure-property relationships using the “fruit fly” of conjugated polymers, poly(3-hexylthiophene) (P3HT). Herein, we demonstrate facile solution processing methods that focus on blending multiple components to target the formation of interconnected assemblies. P3HT is the canonical semicrystalline conjugated polymer, and was used to investigate the mechanism of self-assembly in solution. The polymer molecular weight distribution, solute-solvent interactions, and quantity of seed nuclei are shown to be tunable parameters impacting the degree of interconnectivity. These approaches were investigated using a wide array of strategies to induce nucleation, including exposure to low dose UV, microfluidic flow processing, and poor solvent addition. A particularly promising approach involves the selective mixing of a nucleated polymer solution with a non-nucleated sample via seed nucleation. These processing approaches have improved the charge carrier mobility from a base of ~10-3 cm2/V-s to values exceeding 2x10-1 cm2/V-s. Process-structure-property relationships were developed to quantitatively describe the tradeoffs between polymer network formation and grain boundaries on charge transport. All examined cases suggest an optimal processing window for long range interconnectivity, in which a moderate level of crystallinity is associated with the highest mobility. Finally, materials informatics approaches were leveraged to develop process-property relationships to help guide the next level of experimental efforts. A database of 218 data points from 19 publications on P3HT was created with mobility values ranging from 1.0x10-6 to 2.8 x10-1 cm2/V-s. A classification technique in which devices were sorted into high performing and low performing was applied. A reduced design space containing all high performing points, as well as some having poor performance, is identified for the purpose of focusing future experiments.
Advisors/Committee Members: Grover, Martha (advisor), Reichmanis, Elsa (advisor), Filler, Michael (committee member), Meredith, Carson (committee member), Collard, David (committee member).
Subjects/Keywords: Conjugated polymerps; P3HT; Self-assembly; Material informatics
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APA (6th Edition):
McBride, M. A. (2019). Solution processing via blending approaches to control self-assembly of conjugated polymers. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62686
Chicago Manual of Style (16th Edition):
McBride, Michael A. “Solution processing via blending approaches to control self-assembly of conjugated polymers.” 2019. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/62686.
MLA Handbook (7th Edition):
McBride, Michael A. “Solution processing via blending approaches to control self-assembly of conjugated polymers.” 2019. Web. 18 Jan 2021.
Vancouver:
McBride MA. Solution processing via blending approaches to control self-assembly of conjugated polymers. [Internet] [Doctoral dissertation]. Georgia Tech; 2019. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/62686.
Council of Science Editors:
McBride MA. Solution processing via blending approaches to control self-assembly of conjugated polymers. [Doctoral Dissertation]. Georgia Tech; 2019. Available from: http://hdl.handle.net/1853/62686
Georgia Tech
5.
Hudson, Benjamin Cole.
Solid-state NMR structural characterization of self-assembling peptide analogues.
Degree: PhD, Chemical and Biomolecular Engineering, 2018, Georgia Tech
URL: http://hdl.handle.net/1853/62215
► Research in the field of designer nanostructure has shown great potential for use of peptides, peptide analogues, and a wide array of small molecules in…
(more)
▼ Research in the field of designer nanostructure has shown great potential for use of peptides, peptide analogues, and a wide array of small molecules in a variety of industries and applications. As the field continues to expand, the need for techniques which are capable of providing structural detail at atomic-level resolution will only grow. The question of how best to extract atomic-level structural detail from these systems has yet to be adequately addressed, however. Here I show the efficacy of solid-state nuclear magnetic resonance (NMR) in extracting molecular-level detail from two self-assembling peptide analogues: peptoid B28 and fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF). A study of peptoid B28 nanosheets has shown the capability of dipolar recoupling solid-state NMR to distinguish between the cis and trans configurations of peptoid backbone amide bonds, providing refined physical constraints for an evolving B28 nanosheet molecular model and revealing previously unconsidered peptoid backbone folding behavior. My study of Fmoc-FF suggests this system is highly polymorphic despite its small size, and that the polymorphism appears to be dependent on solvent environment. Despite this polymorphism however, two-dimensional solid-state NMR indicates each of our Fmoc-FF systems feature a common backbone hydrogen-bonding pattern of diphenylalanine sidechains inconsistent with the most widely accepted Fmoc-FF nanofiber model.
Solid-state NMR has never been applied either peptoid B28 or Fmoc-FF, nor is there any evidence in the literature that it has ever been applied a peptoid system or Fmoc-dipeptide. I am borrowing these solid-state NMR experiments from peptide characterization methods and applying them to probe for structural phenomena that has never been tested in either system. I have simply looked at the proposed molecular arrangements in both peptoid B28 and Fmoc-FF and applied measurements sensitive to the details I want to see. This is a not a standard application of solid-state NMR, but nothing new ever began as standard.
Advisors/Committee Members: Paravastu, Anant K. (advisor), Champion, Julie (committee member), Bommarius, Andreas (committee member), Grover, Martha (committee member), Lieberman, Raquel (committee member).
Subjects/Keywords: Solid-state NMR; Peptide analogue; Peptoid nanosheet; Low molecular weight gelator
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APA (6th Edition):
Hudson, B. C. (2018). Solid-state NMR structural characterization of self-assembling peptide analogues. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/62215
Chicago Manual of Style (16th Edition):
Hudson, Benjamin Cole. “Solid-state NMR structural characterization of self-assembling peptide analogues.” 2018. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/62215.
MLA Handbook (7th Edition):
Hudson, Benjamin Cole. “Solid-state NMR structural characterization of self-assembling peptide analogues.” 2018. Web. 18 Jan 2021.
Vancouver:
Hudson BC. Solid-state NMR structural characterization of self-assembling peptide analogues. [Internet] [Doctoral dissertation]. Georgia Tech; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/62215.
Council of Science Editors:
Hudson BC. Solid-state NMR structural characterization of self-assembling peptide analogues. [Doctoral Dissertation]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/62215
Georgia Tech
6.
Olanrewaju, Kayode Olaseni.
The rheology and phase separation kinetics of mixed-matrix membrane dopes.
Degree: PhD, Chemical Engineering, 2011, Georgia Tech
URL: http://hdl.handle.net/1853/39466
► Mixed-matrix hollow fiber membranes are being developed to offer more efficient gas separations applications than what the current technologies allow. Mixed-matrix membranes (MMMs) are membranes…
(more)
▼ Mixed-matrix hollow fiber membranes are being developed to offer more efficient gas separations applications than what the current technologies allow. Mixed-matrix membranes (MMMs) are membranes in which molecular sieves incorporated in a polymer matrix do separation between gas mixtures based on the molecular size difference and/or adsorption properties of the component gases vis-à-vis the porous structure and the nature of adsorption sites in the molecular sieve. The development of MMMs to deliver on its promises has however been slow. The major challenges encountered in the efficient development of MMMs are associated with some of the paradigm shifts involved in their processing. For instance, mixed-matrix hollow fiber membranes are prepared by a dry-wet jet spinning method. For an efficient large scale processing of hollow fibers the rheology and kinetics of phase separation of the MMM dopes are important control variables in the process design. Therefore, this research thesis aims to study the rheology and phase separation kinetics of mixed-matrix membrane dopes.
In research efforts to develop predictive models for the shear rheology of suspensions of zeolite particles in polymer solutions it was found that MFI zeolite suspensions have relative viscosities that dramatically exceed the Krieger-Dougherty predictions for hard sphere suspensions. Our investigations show that the major origin of this discrepancy is the selective absorption of solvent molecules from the suspending polymer solution into the zeolite pores. Consequently, both the viscosity of the polymer solution and the particle contribution to the suspension viscosity are greatly increased. A predictive model for the viscosity of porous zeolite suspensions incorporating a solvent absorption parameter, α, into the Krieger-Dougherty model was developed. We experimentally determined the solvent absorption parameter and our results are in good agreement with the theoretical pore volume of MFI particles. In addition, fundamental studies were conducted with spherical nonporous silica suspensions to elucidate the role of colloidal and hydrodynamic forces on the rheology of mixed-matrix membrane dopes.
Also in this thesis, details of a novel microfluidic device that enables measurements of the phase separation kinetics via video-microscopy are presented. Our device provides a well-defined sample geometry and controlled atmosphere for in situ tracking of the phase separation process. We have used this technique to quantify the phase separation kinetics (PSK) of polymer solutions and MMM dopes upon contact with an array of relevant nonsolvent. For the polymer solution, we found that PSK is governed by the micro-rheological and thermodynamic properties of the polymer solution and nonsolvent. For the MMM dopes, we found that the PSK is increased by increased particles surface area as a result of surface diffusion enhancement. In addition, it was found that the dispersed particles alter the thermodynamic quality of the dope based on the hydrophilic and porous…
Advisors/Committee Members: Breedveld, Victor (Committee Chair), Bucknall, David (Committee Member), Grover, Martha (Committee Member), Koros, William (Committee Member), Meredith, Carson (Committee Member).
Subjects/Keywords: Polymer solution; Rheology; Phase separtion kinetics; Membranes; Suspensions; Zeolite particles; Membranes (Technology); Separation (Technology); Zeolites; Rheology; Liquation
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APA (6th Edition):
Olanrewaju, K. O. (2011). The rheology and phase separation kinetics of mixed-matrix membrane dopes. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/39466
Chicago Manual of Style (16th Edition):
Olanrewaju, Kayode Olaseni. “The rheology and phase separation kinetics of mixed-matrix membrane dopes.” 2011. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/39466.
MLA Handbook (7th Edition):
Olanrewaju, Kayode Olaseni. “The rheology and phase separation kinetics of mixed-matrix membrane dopes.” 2011. Web. 18 Jan 2021.
Vancouver:
Olanrewaju KO. The rheology and phase separation kinetics of mixed-matrix membrane dopes. [Internet] [Doctoral dissertation]. Georgia Tech; 2011. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/39466.
Council of Science Editors:
Olanrewaju KO. The rheology and phase separation kinetics of mixed-matrix membrane dopes. [Doctoral Dissertation]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/39466
Georgia Tech
7.
Joshi, Tapesh.
Capacity and power fade in lithium-ion batteries.
Degree: PhD, Chemical and Biomolecular Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/58152
► Lithium-ion batteries are known to have performance degradation as repeated use and age of the batteries increase. It is essential to qualify these batteries to…
(more)
▼ Lithium-ion batteries are known to have performance degradation as repeated use and age of the batteries increase. It is essential to qualify these batteries to meet the performance goals for their intended applications. For batteries requiring long-term use, such as transportation applications in electrified vehicles, experimental testing for extended periods is generally not viable due to high costs associated with long-term testing. To minimize qualification times, accelerated experimental testing and mathematical modeling can be combined to elucidate long-term battery performance. In this work, we have investigated the long-term performance of lithium-ion batteries using accelerated experimental tests. We found that the dissolution of transition metals cause a reduction in cell capacity and cycle stability in full cells. Reduction of transition metal species in the negative electrode facilitated the growth of the solid electrolyte interphase (SEI) by increasing the rate of solvent diffusion through the SEI and the subsequent reduction of the solvent. Capacity and power fading phenomenon in commercial cells were found to occur in two stages that were caused by: (i) lithium loss in the SEI in the negative electrode and (ii) active material dissolution and surface layer growth on the positive electrode. Simulation results on batteries consisting of nickel cobalt manganese (NCM) positive electrode and graphite negative electrode showed good agreement with experimental data. The model was extended to validate capacity fade occurring in commercial cells via lithium loss mechanism.
Advisors/Committee Members: Fuller, Thomas F. (advisor), Yushin, Gleb (advisor), Kohl, Paul A. (committee member), Hess, Dennis W. (committee member), Grover, Martha A. (committee member).
Subjects/Keywords: Lithium-ion batteries; Capacity fade; Power fade; Dissolution; Nickel cobalt manganese (NCM); Graphite; Modeling; Solid electrolyte interphase (SEI); Hybrid electric vehicles (HEV); Lithium loss; SEI growth; Transition metal dissolution
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APA (6th Edition):
Joshi, T. (2016). Capacity and power fade in lithium-ion batteries. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58152
Chicago Manual of Style (16th Edition):
Joshi, Tapesh. “Capacity and power fade in lithium-ion batteries.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/58152.
MLA Handbook (7th Edition):
Joshi, Tapesh. “Capacity and power fade in lithium-ion batteries.” 2016. Web. 18 Jan 2021.
Vancouver:
Joshi T. Capacity and power fade in lithium-ion batteries. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/58152.
Council of Science Editors:
Joshi T. Capacity and power fade in lithium-ion batteries. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/58152
8.
Hui, Ho Yee.
Understand and advancing of semiconductor nanowire synthesis.
Degree: PhD, Chemical and Biomolecular Engineering, 2017, Georgia Tech
URL: http://hdl.handle.net/1853/58314
► Semiconductor nanowires (NWs) have become an indispensable nanoscale platform for a broad range of electronic, photonic, and energy conversion applications. Among all growth technique, the…
(more)
▼ Semiconductor nanowires (NWs) have become an indispensable nanoscale platform for a broad range of electronic, photonic, and energy conversion applications. Among all growth technique, the bottom-up vapor-liquid-solid (VLS) nanowire (NW) fabrication technique offers the ability to encode material functionalities along the length of a NW in a user programmable manner. A robust control of VLS growth requires understanding of multiple heterogeneous chemical processes: (1) transportation of semiconductor molecules/atoms from vapor to liquid droplets or vice versa at the vapor-liquid (VL) interface, (2) crystallization and dissolution of semiconductor atoms at the liquid-solid (LS) interface, and (3) the conformal deposition of precursor molecules onto the nanowire sidewall at the vapor-solid (VS) interface. However, the ability to rationally engineer NWs for advanced semiconductor devices is critically impaired by limited understanding of these chemical processes at the heterogeneous interfaces. Here, through experiments and modeling, nanowires can be selectively removed via solid-liquid-vapor mechanism at the VL and LS interfaces. Similarly, the importance of adsorbates from a prior study at the VS interface is leveraged to fabricate large-area arrays of high quality axial Si/Ge heterostructures for the first time. These findings open the door to engineer nanowire structures along the nanowire length, a capability that can be applied to applications from high performance electronics to ultra-sensitivities (bio) molecular sensors.
Advisors/Committee Members: Filler, Michael A. (advisor), Reichmanis, Elsa (committee member), Grover, Martha A. (committee member), Xia, Younan (committee member), Bassiri-Gharb, Nazanin (committee member).
Subjects/Keywords: Semiconductor nanowire; Nanomaterial
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APA (6th Edition):
Hui, H. Y. (2017). Understand and advancing of semiconductor nanowire synthesis. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58314
Chicago Manual of Style (16th Edition):
Hui, Ho Yee. “Understand and advancing of semiconductor nanowire synthesis.” 2017. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/58314.
MLA Handbook (7th Edition):
Hui, Ho Yee. “Understand and advancing of semiconductor nanowire synthesis.” 2017. Web. 18 Jan 2021.
Vancouver:
Hui HY. Understand and advancing of semiconductor nanowire synthesis. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/58314.
Council of Science Editors:
Hui HY. Understand and advancing of semiconductor nanowire synthesis. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58314
Georgia Tech
9.
Casciato, Michael John.
The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide.
Degree: PhD, Chemical and Biomolecular Engineering, 2013, Georgia Tech
URL: http://hdl.handle.net/1853/49059
► This thesis presents investigations into the design and synthesis of nanomaterials in supercritical carbon dioxide (sc-CO₂) as well as novel experimental design methodologies. First, the…
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▼ This thesis presents investigations into the design and synthesis of nanomaterials in supercritical carbon dioxide (sc-CO₂) as well as novel experimental design methodologies. First, the process-structure-property relationships are studied for the deposition of materials from organometallic precursors in sc-CO₂. The materials that were investigated in these studies were: (1) the semiconductor material copper zinc tin sulfide (Cu₂ZnSnS₄, or CZTS), which has application in solar energy capture; (2) zinc sulfide nanoparticles deposited onto carbon nanotubes, which have application in optoelectronics; and (3) silver nanoparticles deposited on silicon and glass wafer surfaces, which find application as biosensors via surface enhanced Raman spectroscopy. Next, two novel experimental design methodologies were implemented. The first is termed layers of experiment with adaptive combined design (LoE/ACD), which efficiently optimizes a process that is expensive and time consuming to study by zooming in on the process optimum through successive layers. The mean silver nanoparticle size was optimized as a function of temperature in the sc-CO₂ system using the LoE/ACD approach. The second experimental design methodology is called initial experimental design (IED). The IED methodology was developed to choose the first round of experiments for a system that is expensive to study (in terms of time and money), poorly understood, and possesses a related, non-identical system that is well-studied. The IED approach was used to optimize the mean iridium nanoparticle size as a function of temperature given expert opinion, prior data, and an engineering model for silver nanoparticles synthesized in sc-CO₂.
Advisors/Committee Members: Grover, Martha A. (advisor), Hess, Dennis W. (advisor), Lu, Jye-Chyi (committee member), Eckert, Charles A. (committee member), Filler, Michael A. (committee member).
Subjects/Keywords: Nanotechnology; Process optimization; Nanomaterials; Nanostructured materials; Supercritical fluids; Carbon dioxide
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APA (6th Edition):
Casciato, M. J. (2013). The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/49059
Chicago Manual of Style (16th Edition):
Casciato, Michael John. “The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide.” 2013. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/49059.
MLA Handbook (7th Edition):
Casciato, Michael John. “The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide.” 2013. Web. 18 Jan 2021.
Vancouver:
Casciato MJ. The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide. [Internet] [Doctoral dissertation]. Georgia Tech; 2013. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/49059.
Council of Science Editors:
Casciato MJ. The design, synthesis, and optimization of nanomaterials fabricated in supercritical carbon dioxide. [Doctoral Dissertation]. Georgia Tech; 2013. Available from: http://hdl.handle.net/1853/49059
Georgia Tech
10.
Mulyadi, Arie Tri Nugroho.
Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications.
Degree: PhD, Chemical and Biomolecular Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/59135
► Modification strategies for cellulose nanofibrils to generate hydrophobic fiber surface and carbon-based fiber were proposed. The enhanced functionality for the obtained nanofiber was utilized for…
(more)
▼ Modification strategies for cellulose nanofibrils to generate hydrophobic fiber surface and carbon-based fiber were proposed. The enhanced functionality for the obtained nanofiber was utilized for diverse engineering applications, such as reinforcing filler for hydrophobic thermoplastic, oil absorbent, and carbon-based electrocatalyst. As the neat cellulose nanofibrils are amphiphilic nanoparticles with relatively high surface energy, surface hydrophobization is an important approach to lower the surface energy and induce hydrophobic-oleophilic surface characteristics. In the case of utilizing cellulose nanofibrils as filler materials, surface compatibility with hydrophobic polymers is a problem that causes an ineffective stress transfer between the filler and polymer matrix. Surface hydrophobization of cellulose nanofibrils was found necessary to improve the tensile strength of the nanocomposite, especially at higher filler loading. Furthermore, the hydrophobic cellulose nanofibrils were found useful to prepare a 3D porous material such as aerogel. The flexible, high porosity, and low density properties of the hydrophobic aerogel allowed the material to have high absorption capacity toward oil/organic solvent and to be compressible. In the case of carbon nanofibers prepared from cellulose nanofibrils precursor, functionalization methods such as heteroatoms-doping and recombination were included to enhance the electrochemical and catalytic activity of the carbon material. The results show that the obtained carbon nanofibers can compete with the graphene-based carbon material as electrocatalysts.
Advisors/Committee Members: Deng, Yulin (advisor), Schork, Francis J. (advisor), Behrens, Sven H. (advisor), Grover, Martha (advisor), Singh, Preet (advisor).
Subjects/Keywords: Cellulose nanofibrils; Composites; Aerogels; Bio-carbons; Electrocatalysts
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APA (6th Edition):
Mulyadi, A. T. N. (2016). Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59135
Chicago Manual of Style (16th Edition):
Mulyadi, Arie Tri Nugroho. “Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/59135.
MLA Handbook (7th Edition):
Mulyadi, Arie Tri Nugroho. “Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications.” 2016. Web. 18 Jan 2021.
Vancouver:
Mulyadi ATN. Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/59135.
Council of Science Editors:
Mulyadi ATN. Functionalization and carbonization of cellulose nanofibrils as high-performance fiber materials and their applications. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/59135
Georgia Tech
11.
Persson, Nils Erland.
Analysis of fibrillar structures for the engineering of polymeric transistors.
Degree: PhD, Chemical and Biomolecular Engineering, 2017, Georgia Tech
URL: http://hdl.handle.net/1853/59187
► Image processing software was developed and applied to the analysis of polymer nanofiber microstructures in poly(3-hexylthiophene) (P3HT)-based organic field effect transistors. A large database of…
(more)
▼ Image processing software was developed and applied to the analysis of polymer nanofiber microstructures in poly(3-hexylthiophene) (P3HT)-based organic field effect transistors. A large database of processing, structural, and electrical property data was collected from the fabrication of bottom gate, bottom contact thin film transistors, including over 100 Atomic Force Microscopy images of densely packed, semi-flexible P3HT nanofibers. Fibers were extracted from the images through a combination of anisotropic diffusion filtering, skeletonization, and vectorization via active contours. Image processing parameters were trained through a machine learning approach, yielding structural measurement error of less than 10% when compared to manual fiber tracing. Numerical methods for the calculation of quantitative structural metrics were developed, including fiber length and width distributions, fiber packing density, fiber alignment, and the decay length of orientational order. Results indicated that fiber alignment was linearly correlated with charge carrier mobility in P3HT-based thin film transistors when fibers were oriented perpendicular to the direction of charge transport. Fiber length was the strongest predictor of alignment, with short fibers causing defects in alignment in blade-coated thin films. These findings suggest that P3HT nanofibers act not as conduits for charge transport, but as hubs through which charges can access longer polymer chains that carry them across the film. Process-structure relationships for the nucleation, growth and alignment of P3HT nanofibers are quantified and discussed for a variety of solution processing techniques, including sonication, UV irradiation, poor solvent addition, aging, and microfluidic flow processing. Finally, techniques from data science and computer vision are applied to the analysis of a large materials microscopy database, demonstrating a new system for the discovery and analysis of microstructural data. The image processing software, GTFiber, is packaged for Windows and Mac and available at [gtfiber.github.io].
Advisors/Committee Members: Grover, Martha A. (advisor), Reichmanis, Elsa (committee member), Meredith, Carson (committee member), Schork, Joseph (committee member), Lu, Jye-Chyi (committee member).
Subjects/Keywords: Organic electronics; Image processing; Machine learning; Fibers
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APA (6th Edition):
Persson, N. E. (2017). Analysis of fibrillar structures for the engineering of polymeric transistors. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59187
Chicago Manual of Style (16th Edition):
Persson, Nils Erland. “Analysis of fibrillar structures for the engineering of polymeric transistors.” 2017. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/59187.
MLA Handbook (7th Edition):
Persson, Nils Erland. “Analysis of fibrillar structures for the engineering of polymeric transistors.” 2017. Web. 18 Jan 2021.
Vancouver:
Persson NE. Analysis of fibrillar structures for the engineering of polymeric transistors. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/59187.
Council of Science Editors:
Persson NE. Analysis of fibrillar structures for the engineering of polymeric transistors. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59187
Georgia Tech
12.
He, Christine Yi.
Viscous solvents as an environment for nucleic acid replication.
Degree: PhD, Chemical and Biomolecular Engineering, 2017, Georgia Tech
URL: http://hdl.handle.net/1853/59762
► Many hypotheses concerning the nature of early life assume that genetic information was once transferred through the template-directed synthesis of RNA, prior to the evolution…
(more)
▼ Many hypotheses concerning the nature of early life assume that genetic information was once transferred through the template-directed synthesis of RNA, prior to the evolution of genetically encoded protein synthesis. However, despite more than half a century of research into the chemical origins of nucleic acids, a robust route to the abiotic synthesis of nucleic acid polymers is unclear. In particular, identifying the earliest mechanism for enzyme-free replication of nucleic acids remains an elusive goal. A biophysical problem known as strand inhibition limits copying of a nucleic acid duplex: transferring information from a template sequence in the presence of its complementary strand is inhibited by the stability of the template duplex. Strand inhibition is a major bottleneck in understanding how sustained RNA replication evolved on the early Earth. In this thesis, I describe a robust, prebiotically plausible route to enzyme-free replication of nucleic acids, driven by hot/cool cycles in viscous environments. Viscous solvents enable kinetic trapping of a nucleic acid duplex as single strands, providing a time window for the assembly and ligation of oligonucleotide substrates on the single stranded templates. I have shown that viscous solvents can be utilized to overcome strand inhibition, enabling copying of a gene-length template duplex (>300 nt), a process which is highly unfavorable in aqueous conditions. Additionally, viscosity enables copying of an RNA duplex containing a hammerhead ribozyme motif, suggesting a potential route for the selection and amplification of catalytically active RNA on the prebiotic Earth.
Advisors/Committee Members: Grover, Martha (advisor), Hud, Nicholas (committee member), Styczynski, Mark (committee member), Loren Williams (committee member), Henderson, Clifford (committee member).
Subjects/Keywords: Viscosity; Nucleic acid replication; RNA world; Prebiotic chemistry; Chemical evolution; Origins of life
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APA (6th Edition):
He, C. Y. (2017). Viscous solvents as an environment for nucleic acid replication. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59762
Chicago Manual of Style (16th Edition):
He, Christine Yi. “Viscous solvents as an environment for nucleic acid replication.” 2017. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/59762.
MLA Handbook (7th Edition):
He, Christine Yi. “Viscous solvents as an environment for nucleic acid replication.” 2017. Web. 18 Jan 2021.
Vancouver:
He CY. Viscous solvents as an environment for nucleic acid replication. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/59762.
Council of Science Editors:
He CY. Viscous solvents as an environment for nucleic acid replication. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/59762
Georgia Tech
13.
Sivaram, Saujan Venkat.
The impact of surface chemistry on stable semiconductor nanowire growth.
Degree: PhD, Chemical and Biomolecular Engineering, 2015, Georgia Tech
URL: http://hdl.handle.net/1853/55509
► The vapor-liquid-solid (VLS) mechanism – whereby a liquid eutectic “catalyst” droplet collects precursor molecules (or atoms) from the vapor and directs crystallization of the solid…
(more)
▼ The vapor-liquid-solid (VLS) mechanism – whereby a liquid eutectic “catalyst” droplet collects precursor molecules (or atoms) from the vapor and directs crystallization of the solid nanowire – is a ubiquitous method for bottom-up nanowire synthesis. In this thesis, we use in situ infrared absorption spectroscopy to identify the previously unknown, yet critical, role of reactive surface intermediates on semiconductor nanowire synthesis. We quantitatively determine the surface coverage of hydrogen atoms by coupling operando measurements with a novel in situ surface titration and show these adsorbates are vital for stable Ge nanowire growth. In the second part of the thesis, we use in situ spectroscopy to explore the interplay between the supercooled AuGe catalyst state and surface chemistry. We find a strong correlation between loss of surface hydrogen and catalyst solidification. To unambiguously identify the influence of surface chemistry on the supercooled AuGe catalyst, we deliver atomic hydrogen to the nanowire sidewall, which prevents Au migration from the supercooled catalyst and preserves the liquid catalyst state in the absence of Ge2H6 flow. We conclude that solidification likely occurs via heterogeneous nucleation in the presence of solid particles near the trijunction region and present general strategies to maintain the supercooled catalyst state in other material systems. Our experiments identify a key chemical mechanism underlying nanowire growth via chemical vapor deposition and demonstrate that changes to surface bonding are critical to understand nanowire synthesis. The fundamental insights shown promise unprecedented control of nanowire structure and function by providing a chemical foundation for rational synthetic design.
Advisors/Committee Members: Filler, Michael A. (advisor), Grover, Martha A. (committee member), Henderson, Clifford L. (committee member), Fedorov, Andrei G. (committee member), Bongiorno, Angelo (committee member).
Subjects/Keywords: Nanowire; Semiconductor; Synthesis; Spectroscopy
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APA (6th Edition):
Sivaram, S. V. (2015). The impact of surface chemistry on stable semiconductor nanowire growth. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/55509
Chicago Manual of Style (16th Edition):
Sivaram, Saujan Venkat. “The impact of surface chemistry on stable semiconductor nanowire growth.” 2015. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/55509.
MLA Handbook (7th Edition):
Sivaram, Saujan Venkat. “The impact of surface chemistry on stable semiconductor nanowire growth.” 2015. Web. 18 Jan 2021.
Vancouver:
Sivaram SV. The impact of surface chemistry on stable semiconductor nanowire growth. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/55509.
Council of Science Editors:
Sivaram SV. The impact of surface chemistry on stable semiconductor nanowire growth. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/55509
Georgia Tech
14.
Griffin, Daniel J.
A framework for understanding and controlling batch cooling crystallization.
Degree: PhD, Chemical and Biomolecular Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/55619
► In taking a different view of crystallization dynamics, this thesis reveals a new framework for addressing a prevalent process engineering challenge: control over the size…
(more)
▼ In taking a different view of crystallization dynamics, this thesis reveals a new framework for addressing a prevalent process engineering challenge: control over the size of crystals produced by batch cooling crystallization. The thesis divides roughly into halves. In the first half, the crystal size control problem is introduced and the proposed framework for addressing this problem—termed the mass-count (MC) framework—is developed. This new framework is laid out along side the population balance (PB) framework, which is the prevailing framework for modeling crystallization dynamics and addressing the crystal size control problem. In putting the proposed and established frameworks side by side, the intent is not to say that one or the other is correct. Rather, the point is to show that they are different perspectives that facilitate different control approaches. The PB framework is built up from first principles; it is intellectually stimulating and mathematically complete, but it has a drawback for application: it does not directly enable feedback control. The MC framework, on the other hand, takes a less detailed view of crystallization dynamics and does not connect to crystallization theory as directly; it is also more conducive to application. In the second half of the thesis, the utility of the MC framework is put to the test. The framework is first applied to understand and model the crystallization dynamics for two widely different systems: darapskite salt crystallization from water and paracetamol crystallization from ethanol. Once the dynamics have been modeled, the framework is then used to develop feedback control schemes. These schemes are applied to both experimental systems and, in both cases, crystal size control is demonstrated.
Advisors/Committee Members: Rousseau, Ronald W. (advisor), Grover, Martha A. (advisor), Kawajiri, Yoshiaki (advisor), Realff, Matthew J. (committee member), Petrovic, Bojan (committee member).
Subjects/Keywords: Batch cooling crystallization; Crystal size control; Process analytical technology; Mass-count plot; Focused beam reflectance measurements; FBRM; Attenuated total reflectance Fourier transform infrared; ATR-FTIRpopulation balance; Population balance; Dynamic programming; Optimal control; Model predictive control; Machine learning; Learning from datadata-driven learning; Data-driven learning; Feedback control
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APA (6th Edition):
Griffin, D. J. (2016). A framework for understanding and controlling batch cooling crystallization. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/55619
Chicago Manual of Style (16th Edition):
Griffin, Daniel J. “A framework for understanding and controlling batch cooling crystallization.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/55619.
MLA Handbook (7th Edition):
Griffin, Daniel J. “A framework for understanding and controlling batch cooling crystallization.” 2016. Web. 18 Jan 2021.
Vancouver:
Griffin DJ. A framework for understanding and controlling batch cooling crystallization. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/55619.
Council of Science Editors:
Griffin DJ. A framework for understanding and controlling batch cooling crystallization. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/55619
Georgia Tech
15.
Brough, David.
Process-structure linkages with materials knowledge systems.
Degree: PhD, Computational Science and Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/56261
► The search for optimal manufacturing process routes that results in the combination of desired properties for any application is a highly dimensional optimization problem due…
(more)
▼ The search for optimal manufacturing process routes that results in the combination of desired properties for any application is a highly dimensional optimization problem due to the hierarchical nature of material structure. Yet, this problem is a key component to materials design. Customized materials data analytics provides a new avenue of research in the efforts to address the challenge described above, while accounting for the inherently stochastic nature of the available data. The analytics mine and curate transferable, high value, materials knowledge at multiple length and time scales. More specifically, this materials knowledge is cast in the form of Process-Structure-Property (PSP) linkages of interest to the design/manufacturing experts. The extension of the novel Materials Knowledge Systems (MKS) framework to Process-Structure linkages holds the exciting potential to development full PSP linkages that can be can be leveraged by experts in data science, manufacturing and materials science and engineering communities. PSP linkages are an essential component in the to realize a modern accelerated materials innovation ecosystem. This work describes the methodologies used to extend the MKS framework to Process-Structure linkages and demonstrates their utility.
Advisors/Committee Members: Kalidindi, Surya (advisor), Aluru, Srinivas (committee member), Garmestani, Hamid (committee member), Grover, Martha A. (committee member), Zha, Hongyuan (committee member).
Subjects/Keywords: Materials knowledge systems; Multiscale simulations; Machine learning; Data sciences; Phase field
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APA ·
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APA (6th Edition):
Brough, D. (2016). Process-structure linkages with materials knowledge systems. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/56261
Chicago Manual of Style (16th Edition):
Brough, David. “Process-structure linkages with materials knowledge systems.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/56261.
MLA Handbook (7th Edition):
Brough, David. “Process-structure linkages with materials knowledge systems.” 2016. Web. 18 Jan 2021.
Vancouver:
Brough D. Process-structure linkages with materials knowledge systems. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/56261.
Council of Science Editors:
Brough D. Process-structure linkages with materials knowledge systems. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/56261
Georgia Tech
16.
Tang, Xun.
Markov state model-based optimal control for colloidal self-assembly.
Degree: PhD, Chemical and Biomolecular Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/56276
► Colloidal self-assembly is widely studied as a promising route to manufacture highly ordered structures for applications as metamaterials. While near-equilibrium self-assembly could produce defect-free crystal,…
(more)
▼ Colloidal self-assembly is widely studied as a promising route to manufacture highly ordered structures for applications as metamaterials. While near-equilibrium self-assembly could produce defect-free crystal, the time required is usually unmanageable in practical applications. On the contrary, rapid assembly via out-of-equilibrium approaches could reduce the amount of process time, but the assembled structure is usually terminated in defective states. Therefore, a gap exists between the speed and the quality of the structure in a colloidal self-assembly system. To overcome this challenge, this thesis proposes a model-based optimization framework for optimal feedback control over a colloidal self-assembly process for rapid assembly of defect-free two-dimensional crystals. The proposed framework features: first, the use of an externally applied electric field as a global actuator to influence the particle movement; second, the use of two order parameters to represent the high-dimensional system in a reduced dimension state space; third, the use of the Markov state model to capture the stochasticity in the system; fourth, the use of dynamic programming to design the optimal control policy; and fifth, the use of an optical microscope for in situ measurements as feedback. The feasibility of the framework is first demonstrated with a static optimal control policy, and its performance is evaluated against fast quench and near-equilibrium approaches. The framework is then expanded to construct a time-dependent optimal control policy, and the performance is compared with widely used time-varying control strategies in both simulation and experiments. The refinement of the framework, more specifically, the construction of the Markov state model is also revisited for better efficiency. The major contributions of this thesis include: (1) it proposes a novel approach to rapidly control colloidal self-assembly processes for perfect crystal with optimal control theories; (2) it demonstrates for the first time in lab, the realization of optimal feedback control of a colloidal self-assembly process; (3) it reveals the benefits of feedback in a stochastic process control, not only to compensate for model inaccuracy, but also to shorten the process time; (4) it also investigates the Markov state model accuracy and provides a more efficient construction of accurate Markov state models. The framework in this study is built on first-principle concepts, and it can be generalized to any molecular, nano-, or micro-scale assembly process where there exists a global actuator to affect the dynamics, a model to represent the relation between the actuator and the system, and a measurement of system state for feedback. Since micron-sized colloidal particles also serve as model systems to study the phase transition behavior and crystallization kinetics for atomic and molecular crystals, the framework can also be extended to these systems for optimal control.
Advisors/Committee Members: Grover, Martha A. (advisor), Behrens, Sven Holger (committee member), Kawajiri, Yoshiaki (committee member), Realff, Matthew J. (committee member), Zhang, Fumin (committee member).
Subjects/Keywords: Markov state model; Optimal control; Dynamic programming; Colloidal self-assembly; Colloidal self assembly; Reduced order modeling
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APA (6th Edition):
Tang, X. (2016). Markov state model-based optimal control for colloidal self-assembly. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/56276
Chicago Manual of Style (16th Edition):
Tang, Xun. “Markov state model-based optimal control for colloidal self-assembly.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/56276.
MLA Handbook (7th Edition):
Tang, Xun. “Markov state model-based optimal control for colloidal self-assembly.” 2016. Web. 18 Jan 2021.
Vancouver:
Tang X. Markov state model-based optimal control for colloidal self-assembly. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/56276.
Council of Science Editors:
Tang X. Markov state model-based optimal control for colloidal self-assembly. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/56276
Georgia Tech
17.
Kim, Jeonghee.
Assessment and modulation of essential tremor using peripheral-nerve stimulation.
Degree: PhD, Electrical and Computer Engineering, 2018, Georgia Tech
URL: http://hdl.handle.net/1853/61105
► Tremor is an abnormal oscillatory movement, observed in patients with essential tremor (ET), Parkinson’s Disease, and other neurological disorders. ET obstructs patient’s movements that require…
(more)
▼ Tremor is an abnormal oscillatory movement, observed in patients with essential tremor (ET), Parkinson’s Disease, and other neurological disorders. ET obstructs patient’s movements that require high degrees of dexterity and precision, resulting in a reduction of the quality of life for the patient. Current quantification methods of ET, which typically rely on subjective ratings by trained clinicians or researchers, are potentially susceptible to inter- and intra-rater variability. Most treatments for reducing tremors, such as medications and thalamic deep brain stimulation, have not been adopted broadly because of the invasiveness of the treatments and their lack of efficacy. To address these limitations, the objectives of this PhD dissertation are (1) to quantitatively assess tremor movement, and (2) to modulate/attenuate tremor movement by adjusting the parameters of electrical stimulation on peripheral nerves using a custom-designed real-time system. I have developed (1) an automatic and quantitative method consisting of three computer-based tasks along with their performance metrics that assess the characteristics of tremor, and (2) a wireless tremor modulation system via peripheral-nerve electrical stimulation using a wearable wrist device. I analyzed that the performance metrics of the proposed computer-based assessment tasks were highly correlated with tremor frequency and power. I found that peripheral-nerve stimulation significantly reduced the tremor frequency and tremor power, and the subject with stronger tremor exhibited a greater reduction in tremor power. I examined the effects of the stimulation parameters (stimulation amplitude, frequency, duty cycle, phase, and stimulation sites), and found that the proper range of stimulation amplitudes varied according to current tremor status. In a future study, I plan to develop a closed-loop optimization algorithm based on tremor characteristics of each patient to maximize the effect of stimulation in tremor modulation.
Advisors/Committee Members: DeWeerth, Stephen P. (advisor), Wichmann, Thomas (committee member), Butera, Robert J. (committee member), Grover, Martha A. (committee member), McKay, J. Lucas (committee member).
Subjects/Keywords: Essential tremor; Fitts’ law; Human motor performance; Kinetic tremor; Peripheral nerve electrical stimulation; Quantitative tremor assessment; Tremor modulation; Wearable tremor measurement
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APA ·
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MLA ·
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APA (6th Edition):
Kim, J. (2018). Assessment and modulation of essential tremor using peripheral-nerve stimulation. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/61105
Chicago Manual of Style (16th Edition):
Kim, Jeonghee. “Assessment and modulation of essential tremor using peripheral-nerve stimulation.” 2018. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/61105.
MLA Handbook (7th Edition):
Kim, Jeonghee. “Assessment and modulation of essential tremor using peripheral-nerve stimulation.” 2018. Web. 18 Jan 2021.
Vancouver:
Kim J. Assessment and modulation of essential tremor using peripheral-nerve stimulation. [Internet] [Doctoral dissertation]. Georgia Tech; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/61105.
Council of Science Editors:
Kim J. Assessment and modulation of essential tremor using peripheral-nerve stimulation. [Doctoral Dissertation]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/61105
18.
Lee, Daniel T.
Mechanism and novel deinking methods for non-impact printed paper.
Degree: MS, Chemical and Biomolecular Engineering, 2014, Georgia Tech
URL: http://hdl.handle.net/1853/53470
► Separation of hydrophilic inks such as pigmented inkjet and flexographic inks has been an issue in paper recycling since the beginning of their use. The…
(more)
▼ Separation of hydrophilic inks such as pigmented inkjet and flexographic inks has been an issue in paper recycling since the beginning of their use. The use of inkjet printing is continuing to increase, and it does not appear that this increase will stop anytime soon. Because of this, it is essential to find an adequate method of deinking these inks for the recycling of paper products. There has been a significant amount of research on methods of improving deinking of these inks, but none have been effective up to this point. Additionally, there has been a significant amount of research studying the effects of deinking parameters on these inks, but there are still gaps in this knowledge. A thorough investigation of deinking chemicals and parameters was conducted in this research along with an investigation of the behavior of the hydrophilic inks during the paper recycling, such as the detachment and reattachment of the ink. Through this analysis, two novel deinking methods were developed to decrease the redeposition and improve the separation of these inks. These methods were adsorption deinking and Liquid Phase Plasma (LPP) treatment. Both of these methods were shown to improve the deinkability of hydrophilic inks. However, LPP treatment was also seen to have a negative impact when hydrophilic inks were mixed with traditional hydrophobic inks. It was hypothesized and shown that LPP treatment has a positive impact on deinking of hydrophilic inks but a negative impact on traditional inks, which led to the development of the adsorption deinking method that can deink both hydrophilic and traditional inks.
Advisors/Committee Members: Hsieh, Jeffery S. (advisor), Grover, Martha (committee member), Hess, Dennis (committee member).
Subjects/Keywords: Deinking; Inkjet; Ink; Adsorption; Liquid plasma
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APA (6th Edition):
Lee, D. T. (2014). Mechanism and novel deinking methods for non-impact printed paper. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53470
Chicago Manual of Style (16th Edition):
Lee, Daniel T. “Mechanism and novel deinking methods for non-impact printed paper.” 2014. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/53470.
MLA Handbook (7th Edition):
Lee, Daniel T. “Mechanism and novel deinking methods for non-impact printed paper.” 2014. Web. 18 Jan 2021.
Vancouver:
Lee DT. Mechanism and novel deinking methods for non-impact printed paper. [Internet] [Masters thesis]. Georgia Tech; 2014. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/53470.
Council of Science Editors:
Lee DT. Mechanism and novel deinking methods for non-impact printed paper. [Masters Thesis]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/53470
19.
Roberts, Evan Kellett.
Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system.
Degree: MS, Chemical and Biomolecular Engineering, 2017, Georgia Tech
URL: http://hdl.handle.net/1853/58744
► This work presents a structural investigation of two variants of SAF (Self-Assembling Fiber) binary peptides designed by Prof. Derek N. Woolfson and coworkers. SAF refers…
(more)
▼ This work presents a structural investigation of two variants of SAF (Self-Assembling Fiber) binary peptides designed by Prof. Derek N. Woolfson and coworkers. SAF refers to pairs of complementary peptides that assemble into coiled coils upon mixing, which then associate with one another to form fibers. Design features hypothesized to drive co-assembly were evaluated by solid-state nuclear magnetic resonance (NMR) spectroscopy. Our results indicate that the SAF assembly mechanism proposed by Woolfson is partially correct. However, it was also discovered that the α-helical structure formed by the initial co-assembly can undergo conversion to a β-sheet structure, and that this conversion is triggered by rehydration of the dried α-helical nanofibers. To our knowledge, this is the first α-β structural transition ever observed in response to physiologically benign stimuli in a co-assembling de novo binary peptide system.
Advisors/Committee Members: Paravastu, Anant K. (advisor), Grover, Martha A. (advisor), Champion, Julie A. (advisor).
Subjects/Keywords: Peptide co-assembly; Supramolecular structure; Structural dynamics; Solid state NMR; Coiled-coil designer peptides
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APA (6th Edition):
Roberts, E. K. (2017). Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58744
Chicago Manual of Style (16th Edition):
Roberts, Evan Kellett. “Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system.” 2017. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/58744.
MLA Handbook (7th Edition):
Roberts, Evan Kellett. “Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system.” 2017. Web. 18 Jan 2021.
Vancouver:
Roberts EK. Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system. [Internet] [Masters thesis]. Georgia Tech; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/58744.
Council of Science Editors:
Roberts EK. Solid state NMR structural evaluation of the SAF-p1/p2a co-assembling peptide nanofiber system. [Masters Thesis]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58744
Georgia Tech
20.
Peters, Andrew J.
Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing.
Degree: PhD, Chemical and Biomolecular Engineering, 2015, Georgia Tech
URL: http://hdl.handle.net/1853/53860
► A molecular dynamics coarse-grained block copolymer (BCP) model was developed and used to studied directed self-assembly (DSA), especially in regards to applications for semiconductor manufacturing.…
(more)
▼ A molecular dynamics coarse-grained block copolymer (BCP) model was developed and used to studied directed self-assembly (DSA), especially in regards to applications for semiconductor manufacturing. Most of the thesis is spent investigating the effect that guiding layer properties and block copolymer properties have on line roughness and defect density in a BCP-DSA process. These two effects are perhaps the most critical in making BCP-DSA a cost efficient industrial process. It is found that guiding patterns have little effect on line roughness and in fact that the BCP heals the majority of roughness in the underlying pattern. BCP properties have a larger effect on line roughness. Segregation strength (as measured by χN, where χ is the Flory- Huggins interaction parameter and N is the degree of polymerization) resulted in a larger than expected increase in line roughness when χN was low. Polydispersity resulted in a moderate increase in line roughness. In regards to equilibrium defect density, free energy calculations showed that χ was the primary determining factor, not χN as many expected. Equilibrium defect density was found to decrease exponentially with increasing χ. Defect density is also found to scale exponentially with polydispersity. Concerning defect heal rate, which can increase the real defect rate of a process if said rate is too low, it is found that increasing χN linearly increased the barrier to defect healing, which means that the defect heal rate decreases exponentially. However, for thin films this is only true for χN > ~ 50. Below χN ~ 50, the barrier is approximately constant. These results give excellent guidance to the type of materials and processes necessary to optimize a BCP-DSA process. A simulation technique designed to more efficiently sample over energy barriers called protracted noise dynamics for polymer systems was developed and studied. It was found that a decrease in simulation time of up to 4 orders of magnitude was achieved. The effect of box size on allowable pitches for a lamellar forming BCP was derived and demonstrated. It was found that more elongated boxes yielded more possible pitches and more accurate results. A short study on the effect of multiblock copolymers on the location of the order-disorder transition was also carried out and it was found that multiblock copolymers had small effect on the ODT. The distribution of chain conformations was also calculated.
Advisors/Committee Members: Henderson, Clifford L. (advisor), Grover, Martha (committee member), Bucknall, David (committee member), Tolbert, Laren M. (committee member), Ludovice, Peter J. (committee member), Meredith, J. Carson (committee member).
Subjects/Keywords: Block copolymer directed self-assembly; Mesoscale simulation; Coarse-grained simulation; Semiconductor manufacturing; Integrated circuit
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APA (6th Edition):
Peters, A. J. (2015). Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53860
Chicago Manual of Style (16th Edition):
Peters, Andrew J. “Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing.” 2015. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/53860.
MLA Handbook (7th Edition):
Peters, Andrew J. “Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing.” 2015. Web. 18 Jan 2021.
Vancouver:
Peters AJ. Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/53860.
Council of Science Editors:
Peters AJ. Mesoscale simulation of block copolymer phase separation and directed self-assembly processes: Applications for semiconductor manufacturing. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53860
Georgia Tech
21.
Agrawal, Gaurav.
Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.
Degree: PhD, Chemical and Biomolecular Engineering, 2014, Georgia Tech
URL: http://hdl.handle.net/1853/54028
► Simulated Moving Bed (SMB) chromatography is a separation process where the components are separated due to their varying affinity towards the stationary phase. Over the…
(more)
▼ Simulated Moving Bed (SMB) chromatography is a separation process where the components are separated due to their varying affinity towards the stationary phase. Over the past decade, many modifications have been proposed in SMB chromatography in order to effectively separate a binary mixture. However, the separation of multi-component mixtures using SMB is still one of the major challenges. Although many different strategies have been proposed, previous studies have rarely performed comprehensive investigations for finding the best ternary separation strategy from various possible alternatives. Furthermore, the concept of combining reaction with SMB has been proposed in the past for driving the equilibrium limited reactions to completion by separating the products from the reaction zone. However, the design of such systems is still challenging due to the complex dynamics of simultaneous reaction and adsorption.
The first objective of the study is to find the best ternary separation strategy among various alternatives design of SMB. The performance of several ternary SMB operating schemes, that are proposed in the literature, are compared in terms of the optimal productivity obtained and the amount of solvent consumed. A multi- objective optimization problem is formulated which maximizes the SMB productivity and purity of intermediate eluting component at the same time. Furthermore, the concept of optimizing a superstructure formulation is proposed, where numerous SMB operating schemes can be incorporated into a single formulation. This superstructure approach has a potential to find more advantageous operating scheme compared to existing operating schemes in the literature.
The second objective of the study is to demonstrate the Generalized Full Cycle (GFC) operation experimentally for the first time, and compare its performance to the JO process. A Semba OctaveTM chromatography system is used as an experimental SMB unit to implement the optimal operating schemes. In addition, a simultaneous optimization and model correction (SOMC) scheme is used to resolve the model mismatch in a systematic way. We also show a systematic comparison of both JO and GFC operations by presenting a Pareto plot of the productivity achieved against the desired purity of the intermediate eluting component experimentally.
The third objective of the study is to develop an simulated moving bed reactor (SMBR) process for an industrial-scale application, and demonstrate the potential of the ModiCon operation for improving the performance of the SMBR compared to the conventional operating strategy. A novel industrial application involving the esterification of acetic acid and 1-methoxy-2-propanol is considered to produce propylene glycol methyl ether (PMA) as the product. A multi-objective optimization study is presented to find the best reactive separation strategy for the production of the PMA product. We also present a Pareto plot that compares the ModiCon operation, which allows periodical change of the feed composition and the…
Advisors/Committee Members: Kawajiri, Yoshiaki (advisor), Realff, Matthew J. (committee member), Grover, Martha (committee member), Nenes, Athanasios (committee member), Bommarius, Andreas S. (committee member), Tsiotras, Panagiotis (committee member).
Subjects/Keywords: Simulated moving bed chromatography; Reactive separation; Parameter estimation; Modeling and optimization; Ternary separation
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APA (6th Edition):
Agrawal, G. (2014). Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/54028
Chicago Manual of Style (16th Edition):
Agrawal, Gaurav. “Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.” 2014. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/54028.
MLA Handbook (7th Edition):
Agrawal, Gaurav. “Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions.” 2014. Web. 18 Jan 2021.
Vancouver:
Agrawal G. Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/54028.
Council of Science Editors:
Agrawal G. Systematic optimization and experimental validation of simulated moving bed chromatography systems for ternary separations and equilibrium limited reactions. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/54028
22.
Moore, Richard Herbert.
Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect.
Degree: PhD, Chemical Engineering, 2011, Georgia Tech
URL: http://hdl.handle.net/1853/45945
► Atmospheric aerosols are known to exert a significant influence on the Earth's climate system; however, the magnitude of this influence is highly uncertain because of…
(more)
▼ Atmospheric aerosols are known to exert a significant influence on the Earth's climate system; however, the magnitude of this influence is highly uncertain because of the complex interaction between aerosols and water vapor to form clouds. Toward reducing this uncertainty, this dissertation outlines a series of laboratory and in-situ field measurements, instrument technique development, and model simulations designed to characterize the ability of aerosols to act as cloud condensation nuclei (CCN) and form cloud droplets. Specifically, we empirically quantify the mixing state and thermodynamic properties of organic aerosols (e.g., hygroscopicity and droplet condensational uptake coefficient) measured in polluted and non-polluted environments including Alaska, California, and
Georgia. It is shown that organic aerosols comprise a substantial portion of the aerosol mass and are often water soluble. CCN measurements are compared to predictions from theory in order to determine the error associated with simplified composition and mixing state assumptions employed by current large-scale models, and these errors are used to constrain the uncertainty of global and regional cloud droplet number and albedo using a recently-developed cloud droplet parameterization adjoint coupled with the GMI chemical transport model. These sensitivities are important because they describe the main determinants of climate forcing. We also present two novel techniques for fast measurements of CCN concentrations with high size, supersaturation, and temporal resolution that substantially improve the state of the art by several orders of magnitude. Ultimately, this work represents a step toward better understanding how atmospheric aerosols influence cloud properties and Earth's climate.
Advisors/Committee Members: Nenes, Athanasios (Committee Chair), Grover, Martha (Committee Member), Huey, Greg (Committee Member), Teja, Amyn (Committee Member), Weber, Rodney (Committee Member).
Subjects/Keywords: Climate change; Aerosol; Cloud condensation nuclei; Instrumentation; Hygroscopicity; Atmospheric aerosols; Atmospheric chemistry; Climatic changes; Cloud physics
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APA (6th Edition):
Moore, R. H. (2011). Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/45945
Chicago Manual of Style (16th Edition):
Moore, Richard Herbert. “Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect.” 2011. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/45945.
MLA Handbook (7th Edition):
Moore, Richard Herbert. “Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect.” 2011. Web. 18 Jan 2021.
Vancouver:
Moore RH. Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect. [Internet] [Doctoral dissertation]. Georgia Tech; 2011. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/45945.
Council of Science Editors:
Moore RH. Using measurements of CCN activity to characterize the mixing state, chemical composition, and droplet growth kinetics of atmospheric aerosols to constrain the aerosol indirect effect. [Doctoral Dissertation]. Georgia Tech; 2011. Available from: http://hdl.handle.net/1853/45945
23.
Kanchanalai, Pakkapol.
New dehydration and pretreatment process for ethanol production from biomass.
Degree: PhD, Chemical and Biomolecular Engineering, 2015, Georgia Tech
URL: http://hdl.handle.net/1853/53559
► The cost of pretreatment process for saccharification from biomass and the cost of dilute ethanol purification are significant components of the overall cost for fuel…
(more)
▼ The cost of pretreatment process for saccharification from biomass and the cost of dilute ethanol purification are significant components of the overall cost for fuel grade ethanol production through fermentation or other biological routes. This work focuses on developing optimal designs of dilute ethanol purification process and the new acid hydrolysis technology for the production of fermentable sugars from biomass where the overarching goal is to reduce the cost of ethanol production from biomass. In this thesis, the ethanol separation process with the reverse osmosis membrane pretreatment is developed to reduce separation cost and energy consumption especially when the feed is dilute. In addition, the new solid phase reactive separation system for biomass saccharification via acid hydrolysis is proposed. This new process is applied for both dilute and concentrated acid hydrolysis where the goal is to increase sugar yield and to reduce byproduct formation. The reaction kinetics of the concentrated acid hydrolysis is investigated through batch experiment. All of these use optimization approaches for seeking the best process designs and for parameter estimations.
Advisors/Committee Members: Kawajiri, Yoshiaki (advisor), Realff, Matthew J. (advisor), Grover, Martha (committee member), Sinquefield, Scott (committee member), Agrawal, Pradeep K. (committee member).
Subjects/Keywords: Bioethanol dehydration; Biomass; Acid hydrolysis; Optimization; Simulated moving bed chromatography
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APA (6th Edition):
Kanchanalai, P. (2015). New dehydration and pretreatment process for ethanol production from biomass. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53559
Chicago Manual of Style (16th Edition):
Kanchanalai, Pakkapol. “New dehydration and pretreatment process for ethanol production from biomass.” 2015. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/53559.
MLA Handbook (7th Edition):
Kanchanalai, Pakkapol. “New dehydration and pretreatment process for ethanol production from biomass.” 2015. Web. 18 Jan 2021.
Vancouver:
Kanchanalai P. New dehydration and pretreatment process for ethanol production from biomass. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/53559.
Council of Science Editors:
Kanchanalai P. New dehydration and pretreatment process for ethanol production from biomass. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53559
24.
Hernandez Moreno, Andres Felipe.
A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations.
Degree: PhD, Chemical Engineering, 2012, Georgia Tech
URL: http://hdl.handle.net/1853/43690
► This thesis describes the implementation of metamodeling approaches as a solution to approximate multivariate, stochastic and dynamic simulations. In the area of statistics, metamodeling (or…
(more)
▼ This thesis describes the implementation of metamodeling approaches as a solution to approximate multivariate, stochastic and dynamic simulations. In the area of statistics, metamodeling (or ``model of a model") refers to the scenario where an empirical model is build based on simulated data. In this thesis, this idea is exploited by using pre-recorded dynamic simulations as a source of simulated dynamic data. Based on this simulated dynamic data, an empirical model is trained to map the dynamic evolution of the system from the current discrete time step, to the next discrete time step. Therefore, it is possible to approximate the dynamics of the complex dynamic simulation, by iteratively applying the trained empirical model. The rationale in creating such approximate dynamic representation is that the empirical models / metamodels are much more affordable to compute than the original dynamic simulation, while having an acceptable prediction error.
The successful implementation of metamodeling approaches, as approximations of complex dynamic simulations, requires understanding of the propagation of error during the iterative process. Prediction errors made by the empirical model at earlier times of the iterative process propagate into future predictions of the model. The propagation of error means that the trained empirical model will deviate from the expensive dynamic simulation because of its own errors. Based on this idea, Gaussian process model is chosen as the metamodeling approach for the approximation of expensive dynamic simulations in this thesis. This empirical model was selected not only for its flexibility and error estimation properties, but also because it can illustrate relevant issues to be considered if other metamodeling approaches were used for this purpose.
Advisors/Committee Members: Grover, Martha (Committee Chair), Henderson, Clifford (Committee Member), Realff, Matthew (Committee Member), Shamma, Jeff (Committee Member), Vengazhiyil, Roshan (Committee Member).
Subjects/Keywords: Metamodeling; Gaussian process model; System dynamics; System identification; Error estimation; Simulation methods; Gaussian processes
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APA (6th Edition):
Hernandez Moreno, A. F. (2012). A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/43690
Chicago Manual of Style (16th Edition):
Hernandez Moreno, Andres Felipe. “A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations.” 2012. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/43690.
MLA Handbook (7th Edition):
Hernandez Moreno, Andres Felipe. “A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations.” 2012. Web. 18 Jan 2021.
Vancouver:
Hernandez Moreno AF. A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations. [Internet] [Doctoral dissertation]. Georgia Tech; 2012. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/43690.
Council of Science Editors:
Hernandez Moreno AF. A metamodeling approach for approximation of multivariate, stochastic and dynamic simulations. [Doctoral Dissertation]. Georgia Tech; 2012. Available from: http://hdl.handle.net/1853/43690
25.
Li, Huayu.
Process measurements and kinetics of unseeded batch cooling crystallization.
Degree: PhD, Chemical and Biomolecular Engineering, 2015, Georgia Tech
URL: http://hdl.handle.net/1853/53503
► This thesis describes the development of an empirical model of focus beam reflectance measurements (FBRM) and the application of the model to monitoring batch cooling…
(more)
▼ This thesis describes the development of an empirical model of focus beam reflectance measurements (FBRM) and the application of the model to monitoring batch cooling crystallization and extracting information on crystallization kinetics.
Batch crystallization is widely used in the fine chemical and pharmaceutical industries to purify and separate solid products. The crystal size distribution (CSD) of the final product greatly influences the product characteristics, such as purity, stability, and bioavailability. It also has a great effect on downstream processing. To achieve a desired CSD of the final product, batch crystallization processes need to be monitored, understood, and controlled.
FBRM is a promising technique for in situ determination of the CSD. It is based on scattering of laser light and provides a chord-length distribution (CLD), which is a complex function of crystal geometry. In this thesis, an empirical correlation between CSDs and CLDs is established and applied in place of existing first-principles FBRM models. Built from experimental data, the empirical mapping of CSD and CLD is advantageous in representing some effects that are difficult to quantify by mathematical and physical expressions. The developed model enables computation of the CSD from measured CLDs, which can be followed during the evolution of the crystal population during batch cooling crystallization processes.
Paracetamol, a common drug product also known as acetaminophen, is selected as the model compound in this thesis study. The empirical model was first established and verified in a paracetamol-nonsolvent (toluene) slurry, and later applied to the paracetamol-ethanol crystallization system. Complementary to the FBRM measurements, solute concentrations in the liquid phase were determined by in situ infrared spectra, and they were jointly implemented to monitor the crystallization process.
The framework of measuring the CSD and the solute concentration allows the estimation of crystallization kinetics, including those for primary nucleation, secondary nucleation, and crystal growth. These parameters were determined simultaneously by fitting the full population balance model to process measurements obtained from multiple unseeded paracetamol-ethanol crystallization runs.
The major contributions of this thesis study are (1) providing a novel methodology for using FBRM measurements to estimate CSD; (2) development of an experimental protocol that provided data sets rich in information on crystal growth and primary and secondary nucleation; (3) interpretation of kinetics so that appropriate model parameters could be extracted from fitting population balances to experimental data; (4) identification of the potential importance of secondary nucleation relative to primary nucleation. The protocol and methods developed in this study can be applied to other systems for evaluating and improving batch crystallization processes.
Advisors/Committee Members: Kawajiri, Yoshiaki (advisor), Rousseau, Ronald W. (advisor), Grover, Martha A. (advisor), Nenes, Athanasios (committee member), Fernández, Facundo M. (committee member).
Subjects/Keywords: Crystallization; Crystal size distribution; Focused beam reflectance measurement; Population balance modeling; Parameter estimation; Nucleation; Crystal growth
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APA (6th Edition):
Li, H. (2015). Process measurements and kinetics of unseeded batch cooling crystallization. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/53503
Chicago Manual of Style (16th Edition):
Li, Huayu. “Process measurements and kinetics of unseeded batch cooling crystallization.” 2015. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/53503.
MLA Handbook (7th Edition):
Li, Huayu. “Process measurements and kinetics of unseeded batch cooling crystallization.” 2015. Web. 18 Jan 2021.
Vancouver:
Li H. Process measurements and kinetics of unseeded batch cooling crystallization. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/53503.
Council of Science Editors:
Li H. Process measurements and kinetics of unseeded batch cooling crystallization. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/53503
26.
Clairmont, Ryan Michael.
Azolium ions: A versatile framework for chemistry on early earth.
Degree: PhD, Chemical and Biomolecular Engineering, 2016, Georgia Tech
URL: http://hdl.handle.net/1853/55021
► This work examines azolium catalysis of the small molecules formaldehyde and glyoxylic acid to yield product sugars as the starting point for synthesis of new…
(more)
▼ This work examines azolium catalysis of the small molecules formaldehyde and glyoxylic acid to yield product sugars as the starting point for synthesis of new azolium catalysts. It is broken into two projects: the first focusing on developing a proof of concept process to couple the two reactions, and the second expanding the reaction space using different solvents and catalyst. From these projects, a model for chemical evolution of small molecule catalysts was proposed. Reaction stoichiometry suggests that the process displays autocatalysis; however, the reactions were conducted separately so that kinetic enhancement was not observed. Even without kinetic enhancement, the findings indicate that synthesis of new catalyst from formaldehyde as the sole carbon source is possible, and that the process is robust due to effects such as catalyst deactivation or other loss pathways over time. Alternative work using glyoxylic acid demonstrated that the kinetics for carbohydrate synthesis are much slower.
Advisors/Committee Members: Bommarius, Andreas S. (advisor), Liotta, Charles L. (advisor), Schork, Francis J. (advisor), Grover, Martha (advisor), Weber, Arthur (advisor).
Subjects/Keywords: Azolium; Autocatalysis; Prebiotic
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APA (6th Edition):
Clairmont, R. M. (2016). Azolium ions: A versatile framework for chemistry on early earth. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/55021
Chicago Manual of Style (16th Edition):
Clairmont, Ryan Michael. “Azolium ions: A versatile framework for chemistry on early earth.” 2016. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/55021.
MLA Handbook (7th Edition):
Clairmont, Ryan Michael. “Azolium ions: A versatile framework for chemistry on early earth.” 2016. Web. 18 Jan 2021.
Vancouver:
Clairmont RM. Azolium ions: A versatile framework for chemistry on early earth. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/55021.
Council of Science Editors:
Clairmont RM. Azolium ions: A versatile framework for chemistry on early earth. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/55021
27.
Liu, Peng.
Impact of climate-responsive strategies on future air quality under climate change.
Degree: PhD, Chemical and Biomolecular Engineering, 2015, Georgia Tech
URL: http://hdl.handle.net/1853/58140
► Air quality has been an important concern related to public health. In order to keep improving air quality under future conditions, additional challenges have been…
(more)
▼ Air quality has been an important concern related to public health. In order to keep improving air quality under future conditions, additional challenges have been brought to the current and potential strategies due to a variety of potential global changes. This research investigates how U.S. air quality will be affected by climate change and climate adaptation strategies motivated by climate change. A broad range of topics is involved that address the impacts of anthropogenic land use change and emissions of atmospheric particles on urban and regional climate and air quality. These impacts constitute one of the largest sources of uncertainty in assessments of anthropogenic climate change overall. The thesis work falls into two categories in general. The first is to improve regional climate and air quality modeling from the following aspects: nudging approach for dynamic downscaling, sub-grid approach for Noah land surface model, and the coupling of aerosol emissions with clouds and the hydrological cycle in the regional model. The second category of work involves evaluation of the modeling frameworks and their applications, in order to study the impact on regional climate and air quality (especially in the southeastern USA) of important regional forcing, including land use/land cover (LULC) change and biomass burning. The applications of the above model frameworks include: (A) the impact of climate responsive strategies on future climate and air quality, (B) the impact of LULC on urban heat island and heat related death, and (C) the impact on regional climate and air quality of biomass burning aerosols owing to the direct effect and bulk property change of clouds, respectively.
Advisors/Committee Members: Nenes, Athanasios (advisor), Russell, Armistead G. (advisor), Sholl, David (committee member), Deng, Yi (committee member), Grover, Martha (committee member).
Subjects/Keywords: Air quality; Climate change; Dynamic downscaling; Nudging; Land use change; Biomass burning
…Dr. Russell), Dr. Yongtao Hu (a senior research
scientist in Georgia Tech)…
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APA (6th Edition):
Liu, P. (2015). Impact of climate-responsive strategies on future air quality under climate change. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58140
Chicago Manual of Style (16th Edition):
Liu, Peng. “Impact of climate-responsive strategies on future air quality under climate change.” 2015. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/58140.
MLA Handbook (7th Edition):
Liu, Peng. “Impact of climate-responsive strategies on future air quality under climate change.” 2015. Web. 18 Jan 2021.
Vancouver:
Liu P. Impact of climate-responsive strategies on future air quality under climate change. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/58140.
Council of Science Editors:
Liu P. Impact of climate-responsive strategies on future air quality under climate change. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/58140
28.
Kernick, Tristan James.
Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement.
Degree: MS, Chemical and Biomolecular Engineering, 2018, Georgia Tech
URL: http://hdl.handle.net/1853/59818
► This thesis uses focused beam reflectance measurement (FBRM) in conjunction with a linear empirical model to measure the solid concentration in a nuclear waste simulant…
(more)
▼ This thesis uses focused beam reflectance measurement (FBRM) in conjunction with a linear empirical model to measure the solid concentration in a nuclear waste simulant in situ. Nuclear waste represents a significant environmental hazard at the Hanford site in Washington State, and the research in this thesis works towards developing a means of monitoring the solid particles present in nuclear waste. The waste simulant, which consisted of six individual components mixed with water, was placed in a stirred vessel and monitored with FBRM at a range of concentrations. The assumptions inherent to the linear model, which incorporates experimentally obtained FBRM histograms from each of the simulant components, were assessed, and the model was applied to two- and three-component mixtures before being used to estimate the composition of the complete simulant. The linear model was capable of estimating the composition of the two-component system containing glass beads and tungsten shavings, and it was able to track changes in composition over time for this simplified system. For the other four components, the model yielded less accurate results. All three large components (alumina, silica, and glass beads from a larger size range) produced much fewer FBRM counts per unit mass of simulant than the smallest three components, making them difficult to detect when the small components were included in the monitored mixture. Silicon carbide, the smallest component in the waste simulant, saturated the FBRM probe at the concentration specified in the simulant, thereby impeding detection of the other five components. Ultimately, the model presented in this thesis can produce accurate composition estimates if the materials being used behave linearly under FBRM observation. For a simple two-component system with particles that backscatter a large percentage of incident light, the linear model has yielded accurate composition estimates with computation times on the order of a few seconds. Materials that generate few chord counts or materials with nonlinear chord count behavior require more advanced models and signal processing to predict composition from their chord length histograms. For the full six-component simulant, the model used in this thesis lacked sufficient complexity to describe the behavior of the system. Further work is necessary to enhance the model’s ability to interpret data produced by multicomponent mixtures.
Advisors/Committee Members: Grover, Martha A. (advisor), Kawajiri, Yoshiaki (committee member), Rousseau, Ronald W. (committee member), Nenes, Athanasios (committee member).
Subjects/Keywords: FBRM; Nuclear waste; Particle monitoring; In situ light backscattering
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APA (6th Edition):
Kernick, T. J. (2018). Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement. (Masters Thesis). Georgia Tech. Retrieved from http://hdl.handle.net/1853/59818
Chicago Manual of Style (16th Edition):
Kernick, Tristan James. “Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement.” 2018. Masters Thesis, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/59818.
MLA Handbook (7th Edition):
Kernick, Tristan James. “Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement.” 2018. Web. 18 Jan 2021.
Vancouver:
Kernick TJ. Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement. [Internet] [Masters thesis]. Georgia Tech; 2018. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/59818.
Council of Science Editors:
Kernick TJ. Estimating the composition of multicomponent particle slurries using focused beam reflectance measurement. [Masters Thesis]. Georgia Tech; 2018. Available from: http://hdl.handle.net/1853/59818
29.
Hsieh, Ming-Chien.
Kinetic and structural evolution of functional peptide assembling networks.
Degree: PhD, Chemical and Biomolecular Engineering, 2017, Georgia Tech
URL: http://hdl.handle.net/1853/58708
► The peptide assembly mechanism is important for the development of both functional biomaterials and clinical therapies. Although the assembly structures and assembling pathways have been…
(more)
▼ The peptide assembly mechanism is important for the development of both functional biomaterials and clinical therapies. Although the assembly structures and assembling pathways have been studied for decades, the complex multistep mechanism remains to be clarified. The main goal of this thesis is to investigate the assembly mechanism of functional peptide assemblies. First, the crucial building blocks capable of assembly are synthesized and selected via the dynamic combinatorial networks (DCNs), which yield sequence-defined oligomers with high fidelity. Both experimental analyses and mathematical modeling are applied to confirm the interplay between the chemical distribution and emergent physical transitions in the networks; model discrimination shows that the chemical nature of the DCNs is affected and shifted at different physical stages. Next, to simulate the two-step nucleation process observed in the DCNs, a peptide assembly model is developed with two-step nucleation. The model simulates the phase transitions between different physical phases, and the potential of this model is tested with experimental results from the peptide, Ac-KLVFFAE-NH2. The model is then extended for a polydisperse system, where the peptides undergo oligomerization, to simulate the chemical and physical transitions in the DCNs. The polydisperse model shows that the physical and chemical distribution may reach the steady state independently. The assembly pathway with two-step nucleation is further experimentally investigated with the pH sensitive Abeta(16-22) peptide, which assembles into fiber at neutral pH but tubes at acidic pH. The difference between the nucleation and propagation environments for the two-step nucleation mechanism affects the assembly kinetics and morphological selection. Although Abeta(16-22) assembles into ribbons pH-independently, the ribbon intermediates undergo pH-dependent reaction pathway and transition into different morphologies under different pH conditions. Finally, the catalytic peptide assemblies are analyzed. The methodol substrate is cleaved by Ac-KLVFFAL-NH2 and Ac-OrnLVFFAL-NH2 nanotubes enantioselectively. The experimental results are analyzed with a modified Michaelis-Menten mechanism to resolve the nature of this catalytic system, including the number of peptides per binding site, the enantioselectivity, and the stability of the tubes. The simulations suggest similar binding pocket size for both nanotubes, and the assemblies are stable throughout the entire reaction time. The enantioselectivity for the R- and S-methodol substrate may come from the chemical selectivity of the peptide nanotubes, but not from the difference of the binding affinity, based on the analysis.
The results from this thesis provide a comprehensive investigation of the construction of functional peptide assemblies. The building block synthesis and selection, the assembly structure and mechanism, and the functional properties of the peptide assemblies are reported and discussed, which may provide a broad insight about…
Advisors/Committee Members: Grover, Martha A. (advisor), Lynn, David G. (advisor), Champion, Julie A. (advisor), Ludovice, Peter J. (advisor), Hud, Nicholas V. (advisor).
Subjects/Keywords: Peptide assembly; Kinetics; Catalysis; System chemistry
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APA (6th Edition):
Hsieh, M. (2017). Kinetic and structural evolution of functional peptide assembling networks. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/58708
Chicago Manual of Style (16th Edition):
Hsieh, Ming-Chien. “Kinetic and structural evolution of functional peptide assembling networks.” 2017. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/58708.
MLA Handbook (7th Edition):
Hsieh, Ming-Chien. “Kinetic and structural evolution of functional peptide assembling networks.” 2017. Web. 18 Jan 2021.
Vancouver:
Hsieh M. Kinetic and structural evolution of functional peptide assembling networks. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/58708.
Council of Science Editors:
Hsieh M. Kinetic and structural evolution of functional peptide assembling networks. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/58708
30.
Ruffing, Anne M.
Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis.
Degree: PhD, Chemical Engineering, 2010, Georgia Tech
URL: http://hdl.handle.net/1853/39507
► Oligosaccharides are important biomolecules that are targets and also components of many medical treatments, including treatments for cancer, HIV, and inflammation. While the demand for…
(more)
▼ Oligosaccharides are important biomolecules that are targets and also components of many medical treatments, including treatments for cancer, HIV, and inflammation. While the demand for medically-relevant oligosaccharides is increasing, these compounds have proven difficult to synthesize. Whole-cell oligosaccharide synthesis is a promising method that requires relatively inexpensive substrates and can complete the synthesis in just one step. However, whole-cell oligosaccharide synthesis employing common microorganisms like E. coli have been plagued by low yields. This dissertation investigates an alternative microorganism for oligosaccharide production: Agrobacterium sp. ATCC 31749. This Agrobacterium strain produces high levels of curdlan polysaccharide, demonstrating its natural ability to produce the sugar nucleotide precursor for oligosaccharide production. The two main objectives of this dissertation are 1) to develop biocatalysts for oligosaccharide synthesis by engineering ATCC 31749 and 2) to determine what factors affect poly- and oligosaccharide production in this Agrobacterium strain. ATCC 31749 was engineered to produce two oligosaccharides of medical importance: N-acetyllactosamine and galactose-α 1,3-lactose. Oligosaccharide production in the biocatalyst was further improved with additional metabolic engineering. Substrate uptake was increased through expression of a lactose permease, and availability of the sugar nucleotide substrate improved with gene knockout of the curdlan synthase gene. Both of these engineering efforts led to increased oligosaccharide synthesis in the Agrobacterium biocatalyst. Overall, the engineered Agrobacterium strains synthesized gram-scale quantities of the oligosaccharide products in just one step and requiring only a few inexpensive substrates and cofactors. Additional improvement of the oligosaccharide-producing biocatalysts required further investigation of the factors influencing poly- and oligosaccharide production in ATCC 31749. In this dissertation, several environmental and intracellular factors are identified that affect both oligosaccharide and curdlan production. Sucrose was the preferred carbon source for oligosaccharide synthesis, and the addition of citrate to the synthesis reaction led to significant improvement in oligosaccharide production. To identify the genetic factors and possible mechanisms regulating curdlan production, the genome of ATCC 31749 was sequenced. The genome sequence was utilized for transcriptome analysis of ATCC 31749. In the transcriptome analysis, genes significantly up- and down-regulated during curdlan production were identified. Subsequent gene knockout experiments showed several factors to be important for curdlan synthesis, namely the nitrogen signaling cascade, polyphosphate, and the GTP-derived second messengers (p)ppGpp and c-di-GMP. In addition to the development of biocatalysts for oligosaccharide production, this investigation provides insight into the complex mechanisms regulating exopolysaccharide synthesis.
Advisors/Committee Members: Chen, Rachel (Committee Chair), Doyle, Donald (Committee Member), Grover, Martha (Committee Member), Prausntiz, Mark (Committee Member), Spain, Jim (Committee Member).
Subjects/Keywords: Genome sequencing; Genomics; Transcriptomics; Oligosaccharide; Agrobacterium; Metabolic engineering; Oligosaccharide synthesis; Agrobacterium; Oligosaccharides Synthesis; Enzymes
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APA ·
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MLA ·
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CSE |
Export
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APA (6th Edition):
Ruffing, A. M. (2010). Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/39507
Chicago Manual of Style (16th Edition):
Ruffing, Anne M. “Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis.” 2010. Doctoral Dissertation, Georgia Tech. Accessed January 18, 2021.
http://hdl.handle.net/1853/39507.
MLA Handbook (7th Edition):
Ruffing, Anne M. “Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis.” 2010. Web. 18 Jan 2021.
Vancouver:
Ruffing AM. Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis. [Internet] [Doctoral dissertation]. Georgia Tech; 2010. [cited 2021 Jan 18].
Available from: http://hdl.handle.net/1853/39507.
Council of Science Editors:
Ruffing AM. Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis. [Doctoral Dissertation]. Georgia Tech; 2010. Available from: http://hdl.handle.net/1853/39507
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Open Access Theses and Dissertations
