Search results

Title: Quantitative investigation of the membrane protein degradation mechanism by membrane-integrated AAA protease FtsH under native environments
Creator: Yang, Yiqing (Graduate of Michigan State University)
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "Controlled degradation of misassembled and dispensable proteins is a crucial cellular process for maintaining the quality control of proteomes. In cells, one of the important carriers of this process is AAA+ (ATPases Associated with diverse cellular Activities) proteases, which mediate ATP-dependent proteolysis. The FtsH family proteins are the only membrane integrated AAA+ proteases, which critically contribute to membrane protein degradation. To investigate the mechanisms of membrane...
Show more"Controlled degradation of misassembled and dispensable proteins is a crucial cellular process for maintaining the quality control of proteomes. In cells, one of the important carriers of this process is AAA+ (ATPases Associated with diverse cellular Activities) proteases, which mediate ATP-dependent proteolysis. The FtsH family proteins are the only membrane integrated AAA+ proteases, which critically contribute to membrane protein degradation. To investigate the mechanisms of membrane protein degradation mediated by FtsH, I successfully reconstituted the degradation process using FtsH of E. coli in a lipid bilayer environment (Chapter 2). I also developed a six-helical bundle intramembrane protease GlpG of E. coli into a model membrane substrate to study the quantitative relationship between folding and degradation (Chapter 2). I found that FtsH has a substantial ability to accelerate unfolding of membrane substrates up to 800 fold using ATP hydrolysis, and the intrinsic folding properties of the substrates such as local stability, spontaneous unfolding rates, and hydrophobicity also impact degradation rates. Finally, I quantified the total ATP cost that FtsH consumes to degrade membrane proteins (Chapters 3 and 4). To degrade membrane proteins, FtsH needs to overcome large energetic costs for unfolding substrates in the membranes and extracting them towards its protease domain located outside the membrane. I found that FtsH utilizes ATP hydrolysis in degrading membrane proteins with similar efficiency to other AAA+ proteases in degrading water-soluble substrates. This efficiency is achieved by coupling multiple ATP hydrolysis events to degradation in a highly cooperative manner. These findings provide new insights into the physical principles of ATP-dependent degradation of membrane proteins, and the in vitro system developed will serve as a model for further refining the mechanisms of membrane protein degradation."--Pages ii-iii.
Show less

Title: Electron transfer kinetics and ligand exchange mechanism of copper complexes used in dye-sensitized solar cells
Creator: Wang, Yujue (Graduate of Michigan State University)
Date: 2019
Collection: Electronic Theses & Dissertations
Description: "To reduce the emission problem induced by using fossil fuels, solar energy has become one of the most promising clean energy resources. Different technologies have been developed to support efficient and affordable pathways for solar energy conversion. A dye-sensitized solar cell (DSSC) is considered as a type of promising device for this purpose. Due to complexity of the internal structure of DSSCs, the interaction between different materials influences drastically the performance of the...
Show more"To reduce the emission problem induced by using fossil fuels, solar energy has become one of the most promising clean energy resources. Different technologies have been developed to support efficient and affordable pathways for solar energy conversion. A dye-sensitized solar cell (DSSC) is considered as a type of promising device for this purpose. Due to complexity of the internal structure of DSSCs, the interaction between different materials influences drastically the performance of the cell. Copper coordination complexes in their lower oxidation state, such as Cu(I), have intense color and proper energy gap between their ground and excited states. And Cu(I/II) pair acts as a good redox couple in solution with relatively positive potential energy. Therefore, Cu(I) complexes are promising alternative photosensitizers for DSSCs to the expensive ruthenium complexes, and Cu(I/II) complex pairs are promising outer-sphere redox couples.This dissertation discussed the usage of copper sensitizers in DSSCs and aimed to reveal the reasons for the low performance of the cells. A ligand exchange reaction between the common additive in DSSC electrolyte (4-tert-butylpyridine) and copper complexes was studied. The unique effect of this ligand exchange reaction improved the performance of the cell. Other electron-donating additives are explored, and the goal was to establish a design rule for DSSCs with copper complexes as one of the components."--Page ii.
Show less

Title: I. amhb : (anti)aromaticity-modulated hydrogen bonding. ii. evaluation of implicit solvation models for predicting hydrogen bond free energies
Creator: Kakeshpour, Tayeb
Date: 2019
Collection: Electronic Theses & Dissertations
Description: My doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In...
Show moreMy doctoral research under Professor James E. Jackson focused on hydrogen bonding (H-bonding) using physical organic chemistry tools. In the first chapter, I present how I used quantum chemical simulations, synthetic organic chemistry, NMR spectroscopy, and X-ray crystallography to provide robust theoretical and experimental evidence for an interplay between (anti)aromaticity and H-bond strength of heterocycles, a concept that we dubbed (Anti)aromaticity-Modulated Hydrogen Bonding (AMHB). In the second chapter, I used accurately measured hydrogen bond energies for a range of substrates and solvents to evaluate the performance of implicit solvation models in combination with density functional methods for predicting solution phase hydrogen bond energies. This benchmark study provides useful guidelines for a priori modeling of hydrogen bonding-based designs.Coordinates of the optimized geometries and crystal structures are provided as supplementary materials.
Show less

Title: Selective synthesis of aromatic and saturated organoboron compounds
Creator: Shannon, Timothy Michael
Date: 2019
Collection: Electronic Theses & Dissertations
Description: C-H borylation (CHB) is a method to functionalize C-H bonds. The development of CHB has taken many years but is getting to the point of well-established chemistry. The directed CHB is possible for a variety of differing substrates and differing loctions of direction. A new method for ortho directed CHB of esters amides and ketones was developed through the use of pyridine based monodentate ligands.Using 4-cyano-2-methoxypyridine as a ligand iridium catalyzed CHB of esters ketones and amides...
Show moreC-H borylation (CHB) is a method to functionalize C-H bonds. The development of CHB has taken many years but is getting to the point of well-established chemistry. The directed CHB is possible for a variety of differing substrates and differing loctions of direction. A new method for ortho directed CHB of esters amides and ketones was developed through the use of pyridine based monodentate ligands.Using 4-cyano-2-methoxypyridine as a ligand iridium catalyzed CHB of esters ketones and amides were performed. The mechanism of CHB in this process likely operates through a different rate-determining step than the other C-H borylation methods used as it was found that the kinetic isotope effect data did not clearly support C-H activation as rate-determining.The development of sp3 C-H borylation is not as advanced as sp2 CHB; a 2-step process to generate the same products could be equally desirable. Utilizing a borylation-hydrogenation process the selectivity that have already been developed for sp2 C-H borylation can be used to generate the sp3 carbon boron bond at the desired location. This process has been developed and limitations of it have been investigated.
Show less

Title: Nonlinear optical spectroscopy with ultrafast laser pulses and controlling laser-matter interactions
Creator: Rasskazov, Gennady
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "The goal of my dissertation work was to study nonlinear laser-matter interactions and to obtain a better understanding of the various processes occurring during these interactions. Advances in femtosecond laser technology have become widely adopted in a nonlinear laser spectroscopy and photochemistry. With the extreme temporal and spatial confinements it becomes possible to induce nonlinear responses of the material and to study them with high temporal resolution. The complexity of the...
Show more"The goal of my dissertation work was to study nonlinear laser-matter interactions and to obtain a better understanding of the various processes occurring during these interactions. Advances in femtosecond laser technology have become widely adopted in a nonlinear laser spectroscopy and photochemistry. With the extreme temporal and spatial confinements it becomes possible to induce nonlinear responses of the material and to study them with high temporal resolution. The complexity of the medium response to the excitation field necessitates control the excitation process in order to figure out its origin, for example, inter-or intra-molecular dynamics. Therefore, over the last two decades, femtosecond pulse-shaping methods have been developed to reach an unprecedented level of control over the ultrafast laser waveforms where spectral amplitude and phase can be specified in accordance to expected response. The characterization and tailoring of femtosecond pulses was central for my research projects. Experimental results are presented in three chapters. Chapter 2 focuses on two topics: (1) generation of flat top temporal shape pulses with sharp on and off fronts and no loss of spectral bandwidth for particular spectroscopic applications; (2) characterization of noisy ultrafast laser sources, namely, pulse-to-pulse stability, caused by spectral phase or amplitude noise. Chapter 3 presents the fundamentals of Raman spectroscopy and development of a non-contact no-reagents system operating in the eye-safe 1600-1800 nm wavelength range for standoff trace detection of explosives and high-speed imaging, 0.06 ms per pixel. The system used in this project is based on the latest ideas in coherent Raman spectroscopy and technologies to perform selective coherent vibrational excitation of a particular chemical compound with sensitivity of sub-mg/cm2 . Chapter 4 describes time-resolved transition-state spectroscopy of sodium iodide (NaI) by taking advantage of modern lasers and pulse shaping to better map the low-lying electronic states. High-level ab initio multi-reference configuration interaction and density matrix calculations were used to simulate time dependent wave packet dynamics of NaI pumped to the A 0 + state. The results in this dissertation demonstrate the utility of tailored ultrafast laser pulses. Using advanced laser technology and photonic control methods we gain a better understanding of time-resolved dynamics of a chemical reaction and nonlinear spectroscopy. During my work I got to develop new approaches for characterization of the laser source itself and how to tailor it using pulse shaping. The work presented here should serve future studies on nonlinear laser-matter interactions with a novel photonic control schemes."--Pages ii-iii.
Show less

Title: Iridium catalyzed C-H borylation : improved selectivity by electrostatic and hydrogen-bond interactions and applications to deuteration and ligand synthesis
Creator: Gore, Kristin Anne
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "C-H bonds are pervasive in organic compounds, and methods for their functionalization are of particular interest. One method for functionalizing C-H bonds is through iridium catalyzed C-H borylation. The transformation of C-H bonds to C-B bonds opens up many synthetic routes, because of the versatility of the C-B bond. In the first section, iridium-catalyzed deborylation is used to selectively deuterate aromatic substrates. This method is highly selective as deuterium is only incorporated...
Show more"C-H bonds are pervasive in organic compounds, and methods for their functionalization are of particular interest. One method for functionalizing C-H bonds is through iridium catalyzed C-H borylation. The transformation of C-H bonds to C-B bonds opens up many synthetic routes, because of the versatility of the C-B bond. In the first section, iridium-catalyzed deborylation is used to selectively deuterate aromatic substrates. This method is highly selective as deuterium is only incorporated where the Bpin had previously resided. It is also milder as it does not use harsher acidic conditions, which makes it more applicable to substatrates that may be sensitive to those conditions. The next sections discuss methods for selective C-H borylations of enamines and phenols. The selective borylation reaction of enamines directed by a hydrogen-bonding interaction between the NH of the enamine and O of a boryl is discussed. This method allows of the selective C-H borylation of trans alkene C-H bonds with no borylation observed on the arene for styryl substrates. Then, the traceless protection of phenols by HBpin for C-H borylation is discussed. The protection of the phenols by HBpin leads to electrostatic interactions between the bipyridine ligand of an iridium catalyst and the O-Bglycolate to direct the ortho-borylation. In cases where Bpin is used as the protecting group, phenols with a substituent in the 4-position larger than fluorine generally had >99:1 ortho-selectivity. For phenols with substitution in the 2- or 3-positions or fluorine in the 4-position, Beg was used to increase stability of the transition states and therefore, the ortho-selectivity. In the final section C-H borylation is used to functionalize 1,10-phenanthroline for to provide simple, high yielding routes to functionalized ligands using the versatility of the C-B bond."--Pages ii-iii.
Show less

Title: Micro- and macroscopic photonic control of matter
Creator: Ryabtsev, Anton
Date: 2016
Collection: Electronic Theses & Dissertations
Description: "This dissertation outlines the development of several methods and techniques that enable comprehensive control of laser-matter interactions and nonlinear optical processes using shaped femtosecond pulses. Manipulation of the spectral phases and amplitudes of femtosecond laser pulses provides an effective way to adjust laser parameters, both those intrinsic to pulse generation within a laser and those induced by laser-matter interactions. When coupled with a fundamental understanding of the...
Show more"This dissertation outlines the development of several methods and techniques that enable comprehensive control of laser-matter interactions and nonlinear optical processes using shaped femtosecond pulses. Manipulation of the spectral phases and amplitudes of femtosecond laser pulses provides an effective way to adjust laser parameters, both those intrinsic to pulse generation within a laser and those induced by laser-matter interactions. When coupled with a fundamental understanding of the interactions between a laser's electric field and the molecules in the propagation media, these methods make the behavior of laser pulses predictable and allow the experimental information they carry to be extracted accurately. The ultimate motivation is to enhance the accuracy and reproducibility of spectroscopic measurements and to control nonlinear processes during light-matter interaction using shaped femtosecond pulses. Ultrafast laser systems have become one of the most important scientific tools in femtochemistry, nanoscale material science, chemical detection and sensing, and many other applications where processes occur at femtosecond (fs, 10-15 of a second) timescales or when broad laser bandwidths are required. As with any measuring instrument, it is very important to know system's exact parameters in order to make meaningful, accurate and reproducible measurements. For ultrafast lasers, these parameters are the intensities of the spectral components, the spectral phase, the temporal profile, the pulse energy, and the spatial laser beam profile. Due to broadband nature of ultrafast laser sources, they are very sensitive to propagation media: gaseous, liquid or solid matter along the paths of laser pulses to the sample, including the material of the sample itself. Optical parameters describing the propagation media, such as linear and nonlinear dispersion, and birefringence, as well as physical parameters, such as temperature and pressure, all affect laser pulse parameters. In order for measurements not to be skewed, these interactions need to be taken into account and mitigated at the time of the experiment or handled later in data analysis and simulations. Experimental results are presented in four chapters. Chapter 2 describes two topics: (1) single-shot real-time monitoring and correction of spectral phase drifts, which commonly originate from temperature and pointing fluctuations inside the laser cavity when the pulses are generated; (2) an alloptical method for controlling the dispersion of femtosecond pulses using other pulses. Chapter 3 focuses on the effects of the propagation media--how intense laser pulses modify media and how, in turn, the media modifies them back--and how these effects can be counteracted. Self-action effects in fused silica are discussed, along with some interesting and unexpected results. A method is then proposed for mitigating self-action processes using binary modulation of the spectral phases of laser pulses. Chapter 4 outlines the design of two laser systems, which are specifically tailored for particular spectroscopic applications and incorporate the comprehensive pulse control described in previous chapters. Chapter 5 shows how control of spatial beam characteristics can be applied to measurements of the mechanical motion of microscale particles and how it can potentially be applied to molecular motion. It also describes an experiment on laser-induced flow in air in which attempts were made to control the macroscopic molecular rotation of gases. My research, with a pulse shaper as the enabling tool, provides important insights into ultrafast scientific studies by making femtosecond laser research more predictable, reliable and practical for measurement and control. In the long term, some of the research methods in this thesis may help the transition of femtosecond lasers from the laboratory environment into clinics, factories, airports, and other everyday settings."--Pages ii-iii.
Show less

Title: Protease-containing membranes for rapid, controlled antibody digestion prior to mass spectrometry analysis
Creator: Pang, Yongle
Date: 2017
Collection: Electronic Theses & Dissertations
Description: "Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes...
Show more"Monoclonal antibodies are the fastest growing class of therapeutic drugs because of their high specificities to targeQt cells. Facile analysis of therapeutic mAbs and their post-translational modifications (PTMs) is essential for quality control, and mass spectrometry (MS) is the most powerful tool for antibody characterization. Conventional antibody characterization workflows contain an in-solution digestion step, which is labor-intensive and time-consuming. Protease-containing membranes are an attractive alternative platform for protein digestion because of their high local enzyme concentrations, short radial diffusion distances, rapid convection in pores, simple fabrication and low cost. Additionally, variation of protein residence time in the membrane gives control over the size of proteolytic peptides. This research focuses on developing workflows for monoclonal antibody characterization using functionalized porous membranes. Sequential adsorption of poly (styrene sulfonate) and pepsin in a porous nylon membrane forms a pepsin membrane reactor. Pepsin is inexpensive and catalyzes proteolysis in acidic solutions, which avoids the need to alkylate cysteine residues and limits antibody deamidation. Variation of the residence times (3 ms to 3 s) of antibody solutions in pepsin-containing membranes yields "bottom-up" (1-2 kDa) to 'middle-down' (5-15 kDa) peptides in less than 10 min. These peptic peptides cover the entire sequences of Herceptin and a WatersTM antibody. Compared with the performance of bottom-up (in-solution tryptic digestion) and top-down (intact protein fragmentation) analysis of an antibody light chain, middle-down (in-membrane peptic digestion) analysis gives the highest bond cleavage (99%). In-membrane digestion also facilitates detection of PTMs such as oxidation, deamidation, N-terminal pyroglutamic acid formation and glycosylation. Recently developed protease-containing spin membranes provide an excellent platform for rapid, membrane-based protein digestion prior to ultrahigh-resolution Orbitrap MS analysis. Centrifugation of 100-200 æL of pretreated protein solutions through the pepsin- or trypsin-containing membranes takes less than 1 min and gives nearly 100% coverage of the protein sequences in subsequent direct infusion MS analysis of digests of apomyoglobin and four commercial monoclonal antibodies (Herceptin, Avastin, Rituxan and Vectibix). MS analysis of peptic and tryptic peptides also reveals mAb PTMs such as N-terminal pyroglutamate formation, C-terminal Lysine clipping and glycosylation. Liquid chromatography coupled to tandem mass spectrometry analysis of tryptic spin digests and subsequent MaxQuant data searching show 100% sequence coverage of all four antibody light chains, and 75.1%-98.4% coverage of the heavy chains. Compared to in-solution tryptic digestion of mAbs, spin digestion yields higher sequence coverage and a larger number of unique peptides. In-membrane digestion also facilitates protein sequence comparison. Rapid peptic in-membrane digestion of two antibodies with direct infusion MS analysis accurately reveals the antibody modification site in less than 1 h. Overall, membrane-based protein digestion uses minimal sample preparation time and yields high peptide and sequence coverages for identification of protein PTMs."--Page ii-iii.
Show less

Title: Designing outer-sphere redox shuttles and investigating efficiency limiting electron transfer processes for the advancement of dye sensitized solar cells
Creator: Xie, Yuling
Date: 2016
Collection: Electronic Theses & Dissertations
Description: Dye sensitized solar cells (DSSCs) are considered as a promising alternative technology to harness the solar energy cost-effectively for the purpose of tackling the energy crisis and climate change. The complex but also unique construction of DSSCs offers various designs utilizing abundant and cheap materials. This dissertation focuses on the design and development of one important component in DSSCs, redox shuttles. A primary goal presented here is exploring alternative outer-sphere redox...
Show moreDye sensitized solar cells (DSSCs) are considered as a promising alternative technology to harness the solar energy cost-effectively for the purpose of tackling the energy crisis and climate change. The complex but also unique construction of DSSCs offers various designs utilizing abundant and cheap materials. This dissertation focuses on the design and development of one important component in DSSCs, redox shuttles. A primary goal presented here is exploring alternative outer-sphere redox shuttles which are able to strike a balance between the two efficiency determining electron transfer processes in DSSCs, dye regeneration and electron recombination. Utilizing Marcus theory allows us to investigate the effects of the two processes on overall efficiency and introduce new route for redox shuttles design, i.e. introduction of low spin cobalt-based outer-sphere redox shuttles. Several routes to design low spin cobalt based redox shuttles are discussed. The systematic study of regeneration and recombination in terms of Marcus theory using these redox shuttles is also presented which illustrated the effect of reorganization energy and driving force evolving from the redox shuttle molecular design.
Show less

Title: Interplay of crystal and electronic structure in battery and strongly correlated electron materials
Creator: Davis, Joshua D.
Date: 2016
Collection: Electronic Theses & Dissertations
Description: Alkali and alkaline earth metal batteries, especially lithium-ion batteries, have had increased interest in the last decade. They offer higher energy density storage and quick discharge rates compared to other battery technologies. They power most of our portable electronics including phones and laptops. They have also been recently used more in consumer electric vehicles. Some of the other suggested applications include short term grid relief and storage for renewable energies from solar and...
Show moreAlkali and alkaline earth metal batteries, especially lithium-ion batteries, have had increased interest in the last decade. They offer higher energy density storage and quick discharge rates compared to other battery technologies. They power most of our portable electronics including phones and laptops. They have also been recently used more in consumer electric vehicles. Some of the other suggested applications include short term grid relief and storage for renewable energies from solar and wind sources. However, many lithium-ion batteries have poor thermal stability and are made from less abundant materials. Other derivatives of lithium-ion batteries based on magnesium and sodium have gained interest due to the potential increase in capacitance of bivalent magnesium and increased abundance of sodium. Even though sodium and magnesium-ion batteries could address some of the issues of lithium-ion batteries, they have their own issues to be considered.Many of the lithium-ion cathode materials are transition metal oxides or transition metal polyoxoanions. The electronic structure of these materials typically has strongly correlated electron metal centers. The prospective compound of ordered SrFeO2F has a similar two-dimension transition metal oxide layer to that of many copper oxyfluoride high temperature superconductors. The synthesis of SrFeO2F for this study was compared to the synthetic method of Berry et al. in 2005 and 2008. While neither method produced the ordered SrFeO2F, different magnetic data from each method suggests different localized order around the metal center. Density functional theory studies have predicted different bonding interactions between iron-oxygen bonds and iron-fluorine bonds in terms of both length and spin density. The studies also have suggested that a disordered SrFeO2F structure would be the more thermodynamic stable structure. Future studies could involve looking at magnesium derivatives for potentially new battery materials as the strontium cavities and the oxygen fluorine disorder could introduce large ion conduction pathways.There are many LiFeO2 polymorphs that have been explored as potential lithium ion batteries. The one polymorph that has been the least studied has been that of the T-LiFeO2 structure. It was notable because it is synthesized from the β-NaFeO2 structure through ion exchange. The large cavities of β-NaFeO2 were hypothesized to allow for the intercalation of extra lithium for a multi-redox battery material, T-Li1+xFeO2. While the intercalation of extra lithium has been achieved, only the electrochemical cycling of iron II/III redox couple has been possible through cobalt doping. Room temperature ionic liquids were explored as alternative electrolytes to resist the high-voltage iron III/IV redox, but it proved ineffective. The electronic density of states for the T-Li0.5Show less

Title: Solid state NMR studies of structure and dynamics of membrane associated influenza fusion peptide
Creator: Ghosh, Ujjayini
Date: 2016
Collection: Electronic Theses & Dissertations
Description: "This work seeks to delineate the role of influenza fusion peptide in the process of membrane fusion. Influenza fusion peptide is represented by the 203033 N-terminal residues of the HA2 subunit of the hemagglutinin (HA) protein. The influenza fusion peptide plays an important role in the membrane fusion between the host viral and the host cell endosomal membrane and has pH dependence. The influenza fusion peptide is the most conserved sequence in the in the influenza genome such that a...
Show more"This work seeks to delineate the role of influenza fusion peptide in the process of membrane fusion. Influenza fusion peptide is represented by the 203033 N-terminal residues of the HA2 subunit of the hemagglutinin (HA) protein. The influenza fusion peptide plays an important role in the membrane fusion between the host viral and the host cell endosomal membrane and has pH dependence. The influenza fusion peptide is the most conserved sequence in the in the influenza genome such that a modest mutation can arrest the fusion activity. It was shown that in detergents the structure of the 20 residue and the 23 residue influenza fusion peptide have different structures. However, influenza fusion peptide is a membrane peptide and induces fusion the lipid vesicles and not between the detergent micelles. In this work, solid state NMR was used to study the structure of the influenza fusion peptide in membranes and its correlation to the vesicle fusion. The influenza peptide was chemically synthesized chemically and was used as a model system to study the membrane fusion process. In PC:PG membranes, the influenza fusion peptide adopts closed and semiclosed structure. Both the closed and the semiclosed structure have a helix/turn/helix structure with an interhelical angle of 1030358° and 1403036° respectively. Unlike detergents, the structures of the 20 residue and the 23 residue are very similar in membranes with some minor differences. At low pH or the fusogenic pH, there is a higher fraction of the semiclosed fraction for both the influenza peptide constructs. For the longer peptide, higher fractions of the closed structures were determined. Vesicle fusion assays served as a surrogate for the virus/endosome fusion. Our data supported a iii strong positive correlation between the vesicle fusion and the hydrophobic surface area. Based on these data we proposed that the hydrophobic interaction between HAfp and the membrane is an important factor in HAfp-catalyzed fusion. Solid state NMR has been applied to study the structure and dynamics of lipid molecules in membrane with fusion peptide but the solid-state NMR data are typically the sum over all lipid molecules with only a small fraction of these molecules next to the fusion peptide. My second project primarily utilized 2 H NMR to study the dynamics of the influenza fusion peptide in membranes. This work describes the development and application of the cross polarization with solid or quadrupolar echo. The main idea of the work is to probe the motions of the lipids adjacent/close to the peptide. This method is applied to two different peptides, HIV-fusion peptide and influenza fusion peptide in presence of membranes. By comparing the conventional solid-echo experiment and the newly developed cross polarization with quadrupolar echo, I have seen differences in the lipid dynamics."--Pages ii-iii.
Show less

Title: Effects of low dimensionality on properties of thermoelectrics and strongly electron correlated materials
Creator: Kraemer, Shannon K.
Date: 2016
Collection: Electronic Theses & Dissertations
Description: A study of the effects of low dimensionality, in both composites and single phase bulk materials, on thermoelectric properties was carried out. It is proposed that with the correct set of guidelines, bulk composite materials can achieve quantum confinement, inherently increasing the Seebeck coefficient, and lead to an overall increase the figure of merit. For this study, the binary system, Pb1-xNaxTe-Cd1-xNaxTe, was chosen based on those guidelines. Several synthetic approaches were employed...
Show moreA study of the effects of low dimensionality, in both composites and single phase bulk materials, on thermoelectric properties was carried out. It is proposed that with the correct set of guidelines, bulk composite materials can achieve quantum confinement, inherently increasing the Seebeck coefficient, and lead to an overall increase the figure of merit. For this study, the binary system, Pb1-xNaxTe-Cd1-xNaxTe, was chosen based on those guidelines. Several synthetic approaches were employed to produce bulk quantities of nanostructures that mimic the key features of quantum well superlattices, potentially resulting in quantum confined system. This study led to an investigation of the effects of several different synthetic methods, which includes comparing aqueous based techniques such as SILAR versus inert atmosphere ampoule technique, on the thermoelectric properties of the materials. Sol-gel technique was utilized as a new facile method in synthesizing both PbTe and CdTe. The resulting materials were characterized using: thermogravimetric analysis-differential scanning calorimetry, powder X-ray diffraction, low and high temperature Seebeck and resistivity measurements, laser flash analysis, and Hall effect measurements.An additional study was carried out on the effects of low dimensionality in a lanthanum nickelate family T`-Lnn+1NinO2n+1 (n = 3 and ∞) known to demonstrate strongly correlated electron behavior. These metastable compounds are commonly formed by reducing a parent compound using low temperature techniques. The final metastable compound contains infinite layer NiO2 with Ni1+ in a square planar coordination. The T`-nickelates are of interest, due to the electronic and structural similarities to high temperature superconducting cuprates, where Cu2+ in a square planar coordination, CuO2, is a common structural element. The NiO2 similarity, both isostructural and isoelectronic, to CuO2 may display similar properties. The first parent compound, La4Ni3O10, was synthesized using traditional solid state techniques, sol-gel and ceramic methods, and was then reduced to La4Ni3O8 using hydrogen gas. The same compound was successfully synthesized with 0.20 Cu dopant, La4Ni2.8Cu0.2O8. The samples were characterized through powder X-ray diffraction, and specific heat. The second parent compound, LaNiO3, was synthesized by the same techniques, however, it was reduced to LaNiO2 using a novel solvothermal reduction technique. The same compound was successfully synthesized for the first time as a Cu doped series LaNi1-xCuxO2 where x = 0.05, 0.10, 0.15, 0.20, 0.25. The samples were characterized by powder x-ray diffraction for a structural analysis as well as for cell parameters determination.
Show less

Title: I. Crystallization of CRBPII mutants as a probe for understanding wavelength regulation. II. Reengineering and crystallization of Cellular Retinol Binding Protein II (CRBPII) as a fluorescent tag. III. Synthesis of gamma-carboxy glutamic acid and appli...
Creator: Watson, Camille Theonie
Date: 2016
Collection: Electronic Theses & Dissertations
Description: I. The mechanism by which humans are able to see colors has been an intriguing area of study over the past several decades. This interest comes from the fact that the different opsins bind to a single chromophore, retinal, as a protonated Schiff base and a wavelength range of 420 nm to 560 nm is observed. Different postulations have been put forward and mutagenic studies have been done on rhodopsin in an attempt to explain this phenomenon. Without crystallographic evidence, the results of...
Show moreI. The mechanism by which humans are able to see colors has been an intriguing area of study over the past several decades. This interest comes from the fact that the different opsins bind to a single chromophore, retinal, as a protonated Schiff base and a wavelength range of 420 nm to 560 nm is observed. Different postulations have been put forward and mutagenic studies have been done on rhodopsin in an attempt to explain this phenomenon. Without crystallographic evidence, the results of these experiments proved to be inconclusive. Rhodopsin being a trans-membrane protein is very difficult to crystallize and give poor expression yields. As a result our lab has engineered a small cytosolic protein, Cellular Retinol Binding Protein II (CRBPII), as a rhodopsin mimic. Our studies, with the aid of high resolution crystal structures, have shown that chromophore conformation and complete burial of the chromophore in the binding pocket is essential for wavelength regulation. II. Fluorescent proteins tags are widely used in the field of biological sciences. Fluorescence based assays provide a means of probing protein localization, protein-protein interactions, protein expression and other biological processes without isolation from the cellular environment. Well renown Green Fluorescent Protein (GFP) and modified GFP’s have been developed and are currently widely used as fluorescent tags. There are also non-protein fluorescent tags that are also currently being widely used; these include the SNAP and FLAsH tags. Even with the advent of these fluorophoric protein tags there is still a lack of red and near-IR fluorescent proteins that are bright and photochemically stable. Since Cellular Retinol Binding Protein II (CRBPII), has proven to be a robust system and binds all-trans-retinal in the nanomolar range, we decided to consider other molecules (fluorophores) that would bind as a protonated Schiff base in order to develop a new red fluorescent protein tag. Several chromophores have been used but to date two of them, Merocyanine and Julolidine, has proven to be suitable. We were able to get high resolution crystal structures of CRBPII with Merocyanine, which provided a platform for analyzing the protein-fluorophore interactions to improve the quantum efficiency of the system.III. Gamma-carboxyglutamic acid (Gla) is formed in humans as a post-translational modification of glutamic acid via the vitamin D carboxylase enzyme. This modification allows for tight binding of calcium ions, which allows for calciferation of bones. This modified amino acid is also essential in the blood coagulation cascade processes. The Gla residues are also found in a family of peptides known as the conantokins, which are found in the venom of sea snails of the Conus genus. The metallo-zipper motif was first discovered in these conantokins. The ‘metallo-zipper’ motif provides a novel interface, which is dependent only on metal chelation. It was found that in the presence of metal ions such as Ca2+, Mg2+, Zn2+, and Cu2+, the structure of both Con-G and Con-T is changed from a linear structure to a helical structure. We have devised a new synthesis of gla and made attempts to synthesize different variants of the conantokins.
Show less

Title: Off-line production of singly-charged, transition-metal beams and subsequent collinear laser spectroscopy of neutral, stable 20752075Mn and 20752076Fe
Creator: Klose, Andrew Mark
Date: 2013
Collection: Electronic Theses & Dissertations
Description: Collinear laser spectroscopy was performed on stable isotopes of neutral Fe-56 and Mn-55 in both the ground and excited electronic states. The experiments served as the groundwork for the planned study on the nuclear electromagnetic moments and charge radii of beta unstable Mn and Fe isotopes via laser probing methods at the National Superconducting Cyclotron Laboratory. Ion beams were generated in one of two sources; a commerical plasma ion source, which was used to generate ion beams from...
Show moreCollinear laser spectroscopy was performed on stable isotopes of neutral Fe-56 and Mn-55 in both the ground and excited electronic states. The experiments served as the groundwork for the planned study on the nuclear electromagnetic moments and charge radii of beta unstable Mn and Fe isotopes via laser probing methods at the National Superconducting Cyclotron Laboratory. Ion beams were generated in one of two sources; a commerical plasma ion source, which was used to generate ion beams from metallic and ionic salt charges, and an electron ionization source that produced ion beams from molecular fragmentaion of sublimated organometallic compounds. The ions were accelerated to an energy of 15 keV and co-propagated with single-mode continuous-wave laser light. The ion beam was neutralized via charge-exchange reactions with a Na vapor. Multiple atomic levels in the outgoing atomic beam were populated in the charge-exchange reactions. One transition in neutral 56Fe and two transitions in neutral Mn-55 were separately investigated via laser probing. The Fe transition was the 3d64s2 5D4 $ 3d64s4p 5F5 transition at 372 nm. The transitions investigated in Mn I were the 3d54s2 6S5/2 -> 3d54s4p 6P7/2 transition from the Mn I ground state at 403 nm, and the 3d54s4p 8Po 9/2 -> 3d54s4d 8D11/2 transition at 357 nm. The 8Po 9/2 state is a long-lived metastable state that was semi-resonantly populated in the charge-exchange process. Hyperfine spectra for the transitions were recorded by measuring laser-induced fluorescence from the atoms as a function of effective laser frequency. The frequency of the single resonance peak observed in the Fe-56 spectrum agreed with the accepted value. The hyperfine spectra obtained from the two transitions in Mn-55 I were each analyzed by simultaneously fitting all observed peaks for each transition, and the A and B hyperfine coupling constants were deduced. The respective A and B constants were determined to be -72.2(2) MHz and 2(1) MHz for the 3d54s2 6S5/2 ground state, and 428.9(1) MHz and 60(1) MHz for the 3d54s4p 6P7/2 state, and were found to agree with the literature values. For the 3d54s4p 8Po 9/2 and 3d54s4d 8D11/2 levels, the constants were determined to be A = 455.3(4) MHz and B = 71(6) MHz, and A = 409.4(8) MHz and B = -52(7) MHz, respectively, an order of magnitude more precise than the previously reported values, where available.
Show less

Title: I. Catalytic asymmetric halofunctionalization of olefins : reaction discovery and mechanistic studies ; II. Development of new transformations for further modification of aziridines
Creator: Salehi Marzijarani, Nastaran
Date: 2016
Collection: Electronic Theses & Dissertations
Description: My doctorate research work with Professor Borhan has focused on various aspects of synthetic, mechanistic and physical organic chemistry. These include reaction discovery and optimization, reaction kinetics, mechanistic studies, and computational methods. My work in the area of physical organic chemistry has defined and explored a new parameter; the halenium affinity (HalA) scale, used to predict the reactivity of various functionalities, and exemplified with over 500 molecules and halenium...
Show moreMy doctorate research work with Professor Borhan has focused on various aspects of synthetic, mechanistic and physical organic chemistry. These include reaction discovery and optimization, reaction kinetics, mechanistic studies, and computational methods. My work in the area of physical organic chemistry has defined and explored a new parameter; the halenium affinity (HalA) scale, used to predict the reactivity of various functionalities, and exemplified with over 500 molecules and halenium sources. Various studies were also carried out to understand the mechanistic aspects of chlorocyclization events. My synthetic chemistry studies entail the development of new methodologies toward the preparation of highly functionalized pyrrolidines and piperidines, as well as development of new diastereoselective and enantioselective halofunctionalization reactions.
Show less

Title: Photoinduced electron donor/acceptor processes in colloidal II-VI semiconductor quantum dots and nitroxide free radicals
Creator: Dutta, Poulami
Date: 2016
Collection: Electronic Theses & Dissertations
Description: ABSTRACTPHOTOINDUCED ELECTRON DONOR/ACCEPTOR PROCESSES IN COLLOIDAL II-VISEMICONDUCTOR QUANTUM DOTS AND NITROXIDE FREE RADICALSBYPoulami DuttaElectron transfer (ET) processes are one of the most researched topics for applications rangingfrom energy conversion to catalysis. An exciting variation is utilizing colloidal semiconductornanostructures to explore such processes. Semiconductor quantum dots (QDs) are emerging as anovel class of light harvesting, emitting and charge-separation materials...
Show moreABSTRACTPHOTOINDUCED ELECTRON DONOR/ACCEPTOR PROCESSES IN COLLOIDAL II-VISEMICONDUCTOR QUANTUM DOTS AND NITROXIDE FREE RADICALSBYPoulami DuttaElectron transfer (ET) processes are one of the most researched topics for applications rangingfrom energy conversion to catalysis. An exciting variation is utilizing colloidal semiconductornanostructures to explore such processes. Semiconductor quantum dots (QDs) are emerging as anovel class of light harvesting, emitting and charge-separation materials for applications such assolar energy conversion. Detailed knowledge of the quantitative dissociation of the photogenerated excitons and the interfacial charge- (electron/hole) transfer is essential for optimizationof the overall efficiency of many such applications. Organic free radicals are the attractivecounterparts for studying ET to/from QDs because these undergo single-electron transfer steps inreversible fashion. Nitroxides are an exciting class of stable organic free radicals, which haverecently been demonstrated to be efficient as redox mediators in dye-sensitized solar cells, makingthem even more interesting for the aforementioned studies. This dissertation investigates theinteraction between nitroxide free radicals TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl),4-amino-TEMPO (4-amino- 2,2,6,6-tetramethylpiperidine-1-oxyl) and II-VI semiconductor(CdSe and CdTe) QDs. The nature of interaction in these hybrids has been examined throughground-state UV-Vis absorbance, steady state and time-resolved photoluminescence (PL)spectroscopy, transient absorbance, upconversion photoluminescence spectroscopy and electronparamagnetic resonance (EPR). The detailed analysis of the PL quenching indicates that theintrinsic charge transfer is ultrafast however, the overall quenching is still limited by the lowerbinding capacities and slower diffusion related kinetics. Careful analysis of the time resolved PLdecay kinetics reveal that the decay rate constants are distributed and that the trap states areinvolved in the overall quenching process. The ultrafast hole transfer from CdSe QDs to 4-AminoTEMPO observed here makes this dyad a highly promising candidate for application in quantumdot sensitized solar cells.
Show less

Title: Chiral anion-mediated catalysis : the chemistry of vanol-derived boroxinate and zirconate complexes
Creator: Zhou, Yubai
Date: 2017
Collection: Electronic Theses & Dissertations
Description: A highly enantioselective asymmetric catalytic synthesis of cis- and trans-aziridines can be achieved with multi-component procedure with primary amines, aldehydes and diazo compounds mediated by a chiral boroxinate (BOROX) catalyst generated from VANOL, VAPOL or t-Bu2VANOL ligands. A catalyst controlled asymmetric aziridination is reported based on the previously developed method for the multi-component cis-aziridination. The stereochemistry of the newly formed aziridines is the function of...
Show moreA highly enantioselective asymmetric catalytic synthesis of cis- and trans-aziridines can be achieved with multi-component procedure with primary amines, aldehydes and diazo compounds mediated by a chiral boroxinate (BOROX) catalyst generated from VANOL, VAPOL or t-Bu2VANOL ligands. A catalyst controlled asymmetric aziridination is reported based on the previously developed method for the multi-component cis-aziridination. The stereochemistry of the newly formed aziridines is the function of chiral boroxinate catalyst and is independent of the chiral centers already present in the aldehyde substrates. A series of aldehydes with the chiral centers presented at either α- or β-positions are investigated to find out the diastereoselectivity of the corresponding aziridines from both enantiomers of the BOROX catalyst, as well as the evaluation of ligand control over the diastereoselectivity from the matched and miss-matched pairs. The synthesis of stereoisomers of isoleucine and polyoxamic acid will be discussed as the application of this method.Meanwhile, The three-component catalytic asymmetric synthesis of trans-aziridines is introduced. This method provides direct aziridination of amines, aldehydes and diazoacetamides to give trans-aziridine-2-carboxamides with the chiral boroxinate catalyst. Taken together with our previous reported on the three-component catalytic asymmetric synthesis of cis-aziridines, the three-component aziridination can be controlled to give either cis- or trans-aziridines. The scope of the trans-aziridination is discussed along with the application in the natural product synthesis. As the extension of this methodology, an asymmetric synthesis of α-amino-β-hydroxy amides is developed by the strategy of trans-aziridination/ring-opening cascade reactions with the presence of nucleophilic phenols and carboxylic acids, with decent yields and asymmetric inductions of aminohydroxy amides achieved. The substrate scope of aldehydes and oxygen-nucleophiles will be further explored.In addition, a parallel kinetic resolution of racemic α-iminols is introduced based on the previously developed method of catalytic asymmetric α-iminol rearrangement based on a chiral zirconate complex derived from VANOL ligand. An excellent resolution of the racemic α-iminols with a phenyl and a alkyl migration group to afford a pair of amino ketone regioisomers with high enantiomeric purity. More studies will focus on the stereochemistry to reveal the mechanisms of migration.
Show less

Title: Methodology towards accessing small molecule heterocycles for h20S and TB proteasome modulation
Creator: Bethel, Travis Kordero
Date: 2018
Collection: Electronic Theses & Dissertations
Description: "This dissertation focused on the development and advancement of methodology for accessing imidazoline scaffolds and other small heterocyclic molecules for biological evaluation. Past research within the Tepe group has correlated functionalized 2-imidazolines to proteasome modulation. Further diversification of the methodology for accessing these 2-imidazoline scaffolds, has allowed for the synthesis of a small library of analogs for SAR evaluation with the h20S proteasome. These finding were...
Show more"This dissertation focused on the development and advancement of methodology for accessing imidazoline scaffolds and other small heterocyclic molecules for biological evaluation. Past research within the Tepe group has correlated functionalized 2-imidazolines to proteasome modulation. Further diversification of the methodology for accessing these 2-imidazoline scaffolds, has allowed for the synthesis of a small library of analogs for SAR evaluation with the h20S proteasome. These finding were used to further experimentally model and synthesize more efficacious 2-imidazoline derivates for proteasome modulation. The proteasome is responsible for the degradation of polyubiquitinated proteins in the cell, producing amino acids that can then be used for alternative cellular functions. The introducition of small heterocyclic molecules like 2- imidazolines, bind to the proteasome and lower is efficacy for protein digestion through modulation of its activity."--Page ii.
Show less

Title: Controlling the surface processes of X- and Z-type ligands to tailor the photophysics of II-VI semiconductor nanocrystals
Creator: Saniepay, Mersedeh
Date: 2018
Collection: Electronic Theses & Dissertations
Description: II−VI colloidal semiconductor nanocrystals (NCs), such as CdSe NCs, are often plagued by efficient nonradiative recombination processes that severely limit their use in energy-conversion schemes. While these processes are now well-known to occur at the surface, a full understanding of the exact nature of surface defects and of their role in deactivating the excited states of  NCs has yet to be established, which is partly due to challenges associated with the direct probing of the complex and...
Show moreII−VI colloidal semiconductor nanocrystals (NCs), such as CdSe NCs, are often plagued by efficient nonradiative recombination processes that severely limit their use in energy-conversion schemes. While these processes are now well-known to occur at the surface, a full understanding of the exact nature of surface defects and of their role in deactivating the excited states of  NCs has yet to be established, which is partly due to challenges associated with the direct probing of the complex and dynamic surface of colloidal NCs. In this dissertation, we report a detailed study of the surface of cadmium-rich zinc-blende CdSe NCs. The surfaces of these cadmium-richspecies are characterized by the presence of cadmium carboxylate complexes (CdX2) that act as Lewis acid (Z- type) ligands that passivate under-coordinated selenide surface species. The systematic displacement of CdX2 from the surface by N,N,N′,N′-tetramethylethylene-1,2-diamine (TMEDA) has been studied using a combination of 1H NMR and photoluminescence spectroscopies. We demonstrate the existence of two independent surface sites that differ strikingly in the binding affinity for CdX2 and that are under dynamic equilibrium with each other. A model involving coupled dual equilibria allows a full characterization of the thermodynamics of surface binding (free energy, as well as enthalpic and entropic terms), showing that entropic contributions are responsible for the difference between the two surface sites. Importantly, we demonstrate that cadmium vacancies only lead to important photoluminescence quenching when created on one of the two sites, allowing a complete picture of the surface composition to be drawn where each site is assigned to specific NC facet locale, with CdX2 binding affinity and nonradiative recombinationefficiencies that differ by up to two orders of magnitude.To understand the effect of steric hindrance and types of functional groups in different ligands on X-type ligand exchanges, using NMR, PL and UV-Vis absorption spectroscopy, we studied X-type exchanges on CdSe NCs capped with native carboxylates, with oleic acid, oleyl thiol, benzoic acid and benzenethiol ligands. We discussed the results and occurrence of undesired pathways including displacement of Z-type ligands, and suggested ligand exchange strategies that most likely lead to 100% X-type exchange.The structural complexity of surface of CdS NCs is also discussed in this dissertation. We demonstrate presence of two different sulfur surface defects on CdS NCs with ligand binding equilibrium constants that are two orders of magnitude apart and 20-60% smaller than those of selenium on similar size CdSe NCs. We also correlated the different surface defects to the PL quenching efficiency of CdS NCs.
Show less

Title: Semi-synthesis of aromatic diacids and biosynthesis of kanosamine in Escherichia coli
Creator: Miller, Kelly (Kelly Knight)
Date: 2018
Collection: Electronic Theses & Dissertations
Description: Microbial synthesis of chemicals from biobased feedstocks is an alternative to manufacture of materials derived from petroleum or unconventional gases, such as shale gas and coalbed methane. Aromatic diacids, terephthalic acid, isophthalic acid , and phthalic acid, are valuable compounds for the polymers and plasticizers industry. These diacids are currently manufactured via Amoco Mid-Century oxidation of petroleum-derived para-, meta- and ortho-xylenes, respectively; a process not without...
Show moreMicrobial synthesis of chemicals from biobased feedstocks is an alternative to manufacture of materials derived from petroleum or unconventional gases, such as shale gas and coalbed methane. Aromatic diacids, terephthalic acid, isophthalic acid , and phthalic acid, are valuable compounds for the polymers and plasticizers industry. These diacids are currently manufactured via Amoco Mid-Century oxidation of petroleum-derived para-, meta- and ortho-xylenes, respectively; a process not without environmental and economic challenges. In this work, a semi-synthesis of terephthalic, isophthalic, and phthalic acids is outlined using 2-hydroxymuconic acid as a common synthetic precursor. Recombinant Escherichia coli was utilized combining protocatechuic acid anabolic and catabolic pathways to achieve 1.2 g/L 2-hydroxymuconic acid from D-glucose in fed-batch fermentation. Lewis-acid catalysis was explored in a cycloaddition of 2-hydroxymuconic acid with ethylene to produce terephthalic acid. Cyclization of 2-hydroxymuconic acid afforded 6-carboxy-2-pyrone which was reacted with propiolic acid to afford mixtures of isophthalic and phthalic acids. Propiolic acid from biogas methane and ethylene from bioethanol could maximize the amount of renewable carbon in this semi-synthetic strategy, producing all three petroleum-derived aromatic diacids without the need for Amoco Mid-Century oxidation process. In an additional research trajectory, the production of kanosamine (3-amino-3-deoxy-D-glucose) is evaluated in fed-batch fermentation of recombinant E. coli. Two biosynthesis pathways are reported in the literature: one native to Bacillus subtilis and the other reported in Amycolatopsis mediterranei and Bacillus pumilus. Genes encoding kanosamine biosynthetic enzymes from B. subtilis, A. mediterranei, and B. pumilus are expressed in Escherichia coli to determine whether heterologous expression results in kanosamine accumulation and if the system can be manipulated to maximize kanosamine production. Recombinant E. coli expressing genes from B. subtilis 168 produces 12.7 ± 0.6 g/L kanosamine in a 6% mol/mol yield from D-glucose. Kanosamine yields were increased to 18 ± 1% mol/mol by blocking the Embden-Meyerhoff-Parnas pathway through a mutation in pgi-encoded phosphoglucose isomerase. Enzymes native to A. mediterranei proved to be challenging to efficiently express in E. coli, prompting examination of B. pumilus kanosamine biosynthesis. Expression of B. pumilus SH-B11 genes in E. coli results in 6.3 g/L kanosamine titers in 4.4% mol/mol yield from D-glucose in fed-batch fermentation. In vitro feeding experiments suggest a departure from what is in the literature regarding kanosamine production in Bacillus pumilus.
Show less

MSU Libraries

Digital Repository

Enabled Filters

Pages

Pages

MSU Libraries

Digital Repository

You are here

Search results

Pages

Pages