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Full-Scale Ab Initio Simulation Of Magic-Angle-Spinning Dynamic Nuclear Polarization, Frédéric A. Perras, Muralikrishna Raju, Scott L. Carnahan, Dooman Akbarian, Adri C. T. van Duin, Aaron Rossini, Marek Pruski 2020 Ames Laboratory

Full-Scale Ab Initio Simulation Of Magic-Angle-Spinning Dynamic Nuclear Polarization, Frédéric A. Perras, Muralikrishna Raju, Scott L. Carnahan, Dooman Akbarian, Adri C. T. Van Duin, Aaron Rossini, Marek Pruski

Chemistry Publications

Theoretical models aimed at describing magic-angle-spinning (MAS) dynamic nuclear polarization (DNP) NMR typically face a trade-off between the scientific rigor obtained with a strict quantum mechanical description, and the need for using realistically large spin systems, for instance using phenomenological models. Thus far, neither approach has accurately reproduced experimental results, let alone achieved the generality required to act as a reliable predictive tool. Here, we show that the use of aggressive state-space restrictions and an optimization strategy allows full-scale ab initio MAS-DNP simulations of spin systems containing thousands of nuclei. Our simulations are the first ever to achieve quantitative reproduction ...


Comparison Of The Vibrational Modes Of Thiolated Gold Nanoparticles Undergoing Core-Conversions Via Raman Spectroscopy, William Gregory Cannella Jr. 2020 University of Mississippi

Comparison Of The Vibrational Modes Of Thiolated Gold Nanoparticles Undergoing Core-Conversions Via Raman Spectroscopy, William Gregory Cannella Jr.

Honors Theses

In this project, the vibrational characteristics/vibrational modes are explored via Raman Spectroscopy for thiolated-gold nanoparticles. This class of compounds is also known as gold nanoparticles (AuNPs). They remain of great interest in research areas such as catalysis, gold dependent nanoelectronics, drug delivery, and sensing, due to their unique size-dependent optical, chiroptical, and electronic properties. Vibrational spectroscopy of thiolated gold nanoparticles are oftentimes considered nontrivial as the compounds strongly absorb light in the visible region of the electromagnetic spectrum, are generally considered weak scatterers, and give off large amounts of fluorescence. This combined with their black appearance, susceptibility to localized ...


Study Of Pharmaceutical Tablets Using Raman Mapping, Kyle Joseph Pauly 2020 University of Mississippi

Study Of Pharmaceutical Tablets Using Raman Mapping, Kyle Joseph Pauly

Honors Theses

Covalent bonds are the strongest type of bonds holding molecules together. Based on the pattern of bonding of the molecule, the atoms associated with the bond will vibrate at a specific frequency. Utilizing vibrational spectroscopy, such as Raman spectroscopy, these unique vibrational frequencies can be used to detect the presence of analytes over a selected area. Furthermore, the intensities of the vibrational modes can be tracked to comparatively quantify the concentration of analytes at various locations. This is a method of great importance due to its ability to compare pharmaceutical tablets synthesized with different techniques. Here, the presence and concentration ...


Characterizing The Long-Range And Short-Range Interactions Stabilizing A Model Sh3 Recognition Complex, Colin McClure 2020 Skidmore College

Characterizing The Long-Range And Short-Range Interactions Stabilizing A Model Sh3 Recognition Complex, Colin Mcclure

Senior Theses

SH3 domains are common recognition domains found in many protein complexes of all eukaryotes. Their regulatory functions are involved in cell proliferation, differentiation, cytoskeleton modification and are vital for cellular communication. We have used Molecular Dynamics (MD) simulations to computationally model a common interaction between the AbpSH3 domain and the intrinsically disordered peptide, ArkA. This work is in collaboration with and in support of previous experimental studies of the complex aimed to characterize the binding pathway including NMR, ITC, and chemical denaturation. Specifically, my work focuses on the long-range electrostatic interactions involved in stabilizing the bound AbpSH3- ArkA complex. Previous ...


Raman Spectroscopy Study Of Delta-9-Tetrahydrocannabinol And Cannabidiol And Their Hydrogen-Bonding Activities, Kalee Sigworth 2020 University of Mississippi

Raman Spectroscopy Study Of Delta-9-Tetrahydrocannabinol And Cannabidiol And Their Hydrogen-Bonding Activities, Kalee Sigworth

Honors Theses

Cannabis and products containing its cannabinoids have grown rapidly in acceptance and use in recent years with legalization of cannabis in many countries and US states. Cannabidiol and Delta-9-Tetrahydrocannabinol are two primary cannabinoids in Cannabis that have been shown to produce analgesic effects along with many other positive side effects for the user. These two cannabinoids interact with receptors in the Central and Peripheral Nervous Systems. No spectroscopic study to our knowledge has been performed to analyze the hydrogen bonding effects of interactions between these two cannabinoids and solvents. Here, we employ theoretical Raman spectra through computational methods to study ...


Spectral Narrowing Accompanies Enhanced Spatial Resolution In Saturated Coherent Anti-Stokes Raman Scattering (Cars): Comparisons Of Experiment And Theory, Avinash Singh, Kalyan Santra, Xueyu Song, Jacob W. Petrich, Emily A. Smith 2020 Ames Laboratory

Spectral Narrowing Accompanies Enhanced Spatial Resolution In Saturated Coherent Anti-Stokes Raman Scattering (Cars): Comparisons Of Experiment And Theory, Avinash Singh, Kalyan Santra, Xueyu Song, Jacob W. Petrich, Emily A. Smith

Chemistry Publications

We demonstrate theoretically and confirm experimentally the mechanism by which spectral narrowing accompanies enhanced spatial resolution in a saturated coherent anti-Stokes Raman scattering (CARS) signal that is demodulated at the third harmonic (3f) of the pump modulation frequency (f). Under these modulation conditions, theory predicts a narrowing of the full width at half-maximum (FWHM) of the CARS spectrum by a factor of 2.0 with respect to that of the spectrum obtained by demodulation at the fundamental frequency. Theory also predicts an improvement of spatial resolution by a factor of 1.7. Experimentally, narrowing of the FWHM of the ...


Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn E. Merrill, Bingjie Zhang, Jerry LaRue 2020 Chapman University

Hot Electron Chemistry On Bimetallic Plasmonic Nanoparticles, Bryn E. Merrill, Bingjie Zhang, Jerry Larue

Student Scholar Symposium Abstracts and Posters

Catalysis provides pathways for efficient and selective chemical reactions through the lowering of energy barriers for desired products. Gold nanoparticles (AuNP) show excellent promise as plasmonic catalysts. Localized surface plasmon resonances are oscillations of the electron bath at the surface of a nanoparticle that generate energetically intense electric fields and rapidly decay into energetically excited electrons. The excited electrons have the potential to destabilize strongly bound oxygen atoms through occupation of accessible anti-bonding orbitals. Tuning the anti-bonding orbitals to make them accessible for occupancy will be achieved by coating the AuNP in a thin layer of another transition metal, such ...


Raman Spectroscopic And Quantum Chemical Investigation Of The Effects Of Tri-Methylamine N-Oxide (Tmao) On Hydrated Urea, Hydrated Guanidinium, And Hydrogen Bonded Networks, Genevieve Verville 2020 University of Mississippi

Raman Spectroscopic And Quantum Chemical Investigation Of The Effects Of Tri-Methylamine N-Oxide (Tmao) On Hydrated Urea, Hydrated Guanidinium, And Hydrogen Bonded Networks, Genevieve Verville

Honors Theses

Trimethylamine N-Oxide (TMAO), guanidinium, and urea are three important

osmolytes with their main significance to the biophysical field being in how they

uniquely interact with proteins. TMAO is known to stabilize and counteract the

destabilizing effects of both urea and guanidinium. The exact mechanisms by which

TMAO stabilizes and both guanidinium and urea destabilize folded proteins continue

to be debated in the literature. Some studies suggest that solvent interactions do not

play a large role in TMAO’s stabilizing effects and therefore advocate direct

stabilization, whereas others suggest that TMAO counteracts denaturation primarily

through an indirect effect of strong solvent ...


Adaptation Of A Low-Cost Hyperpolarization Technique For Use With Single-Sided Nmr, Ruth A. Beaver 2020 William & Mary

Adaptation Of A Low-Cost Hyperpolarization Technique For Use With Single-Sided Nmr, Ruth A. Beaver

Undergraduate Honors Theses

Nuclear magnetic resonance (NMR) suffers from inherent signal problems due to low levels of nuclear polarization at room temperature. These problems are especially prevalent in single-sided NMR, which allows for a more flexible measurement geometry and simpler, cheaper instrumentation than traditional NMR. Hyperpolarization techniques can remedy this by providing artificially high levels of polarization for a single measurement. Signal Amplification By Reversible Exchange (SABRE) hyperpolarization is particularly advantageous, since it can be produced quickly using relatively cheap and simple instrumentation. While SABRE hyperpolarization has been successfully demonstrated with traditional NMR, it has not yet been adapted for single-sided NMR. Here ...


Enhancing Upconversion Nanoparticle Performance Of Nayf4: Yb,Tm With Doping Optimization And Shell Addition And Of Nayf4: Yb,Er With Yb,Nd Shell Addition, Ashleigh M. Chov 2020 University of South Dakota

Enhancing Upconversion Nanoparticle Performance Of Nayf4: Yb,Tm With Doping Optimization And Shell Addition And Of Nayf4: Yb,Er With Yb,Nd Shell Addition, Ashleigh M. Chov

Honors Thesis

Upconversion (UC), is a phenomenon that occurs when low-energy excitation (usually near-infrared (NIR)) results in higher-energy emission. Upconversion nanoparticles (UCNPs) are particles less than 100 nm in size that are synthesized using rare earth metals such as Yb, Er, Tm, and Y. UCNPs have important applications in a variety of fields, including bio-imaging, security printing, and latent fingerprint development. Traditional methods for latent fingerprint development such as fluorescent powder dusting have several drawbacks including low contrast, high background interference, and autofluorescence. NIR-to-NIR UCNPs are composed of NaYF4: Yb, Tm and emit 800 nm light under 980 nm excitation due ...


Spectroscopic And Computational Studies Of The Agricultural Active Ingredient Dicamba, James Johnson 2020 University of Mississippi

Spectroscopic And Computational Studies Of The Agricultural Active Ingredient Dicamba, James Johnson

Honors Theses

3,6-dichloro-2-methoxy benzoic acid, more commonly known as Dicamba, is the active ingredient in an array of pesticides used on farmlands across the globe. Dicamba’s mode of action works by mimicking the plant hormone auxin, which is synonymous to growth hormones in mammals. The mimicking of auxin results in excessive elongation and growing, which is eventually fatal for plants when the rate of growth can no longer be sustained. Dicamba has risen in prominence in recent years due to drift damage as a result of Dicamba’s high volatility. Having the ability to identify Dicamba is crucial for the ...


Surface Chemistry And Surface Properties Of Energetic Nitrocellulose (Nc), Henry Grau 2020 Seton Hall University

Surface Chemistry And Surface Properties Of Energetic Nitrocellulose (Nc), Henry Grau

Seton Hall University Dissertations and Theses (ETDs)

This research describes an investigation into the wettability of nitrocellulose (NC), most importantly to nitroglycerin (NG), which are key components of formulations used to propel military ammunition. NG demonstrates complete wetting of NC and, overtime, NG sweats on the NC surface and leaks out. The leaking out of NG from the solid formulation is a known cause of fires and explosions resulting from storage. The origin of this research is inspired by the need to engineer a solution to leakage problems of energetic plasticizer in NC based propellant. While searching for a viable material for a specific application, we journeyed ...


An Investigation Into The Molecular Dynamics Of The Laser Induced Dissociation Of 2-Bromoethanol, Kirk French 2020 Liberty University

An Investigation Into The Molecular Dynamics Of The Laser Induced Dissociation Of 2-Bromoethanol, Kirk French

Senior Honors Theses

The unimolecular dissociation of 2-bromoethanol is investigated using computational chemistry methods both to test the reliability of the theories and methods of computational chemistry and to explore the internal mechanism of the dissociation. The dissociation of the bromine ion from 2-bromoethanol was experimentally observed in a previous publication by Ratliff et. al. These experimental results were compared in this thesis to computational calculations of their research. The method of TD-B3LYP proved to be inadequate in this venture except for the lowest energies of the most stable conformer of 2-bromoethanol. However, interesting mechanisms were found such as the formation of HBr ...


354— Observation Of Acid Penetration Of Nano-Gold Doped Sol-Gel System, Mir Ali, Eric Koessler 2020 SUNY Geneseo

354— Observation Of Acid Penetration Of Nano-Gold Doped Sol-Gel System, Mir Ali, Eric Koessler

GREAT Day

The penetration of the acid into gold doped sol-gel material was measured. The acid penetration speed increased as the nano size increased up from 5 nm to 20 nm. Then there was almost no penetration at 60 nm. The nano dependent rate change was complex and needs to be investigated further. Also, recent new methodology to create the gel showed a significance stability and it took more than a few days to complete the penetration.


Monitoring And Identifying The Rhodamine 6g-Hydroxide Ion Reaction Using In-Situ, Surface-Enhanced Raman Spectroscopy, Ryan Lamb 2020 Western Kentucky University

Monitoring And Identifying The Rhodamine 6g-Hydroxide Ion Reaction Using In-Situ, Surface-Enhanced Raman Spectroscopy, Ryan Lamb

Masters Theses & Specialist Projects

An effective method for monitoring chemical reactions is necessary to better understand their mechanisms and kinetics. Effective reaction monitoring requires a spectroscopy technique with fast data acquisition, high sensitivity, structure-to-spectrum correlation, and low solvent interference. Surface-enhanced Raman spectroscopy (SERS) provides these features, which makes it a valuable tool for monitoring reactions. To obtain the Raman enhancement, metallic nanostructures typically made of silver or gold are aggregated using a salt. The nanoparticles aggregates must then be stabilized using a surfactant to use this method in situ due to eventual nanoparticle precipitation. In this study, gold nanoparticles stabilized with sodium dodecyl sulfate ...


Fundamentals Of Au(111) Surface Dynamics: Coarsening Of 2d Au Islands, Peter M. Spurgeon, King C. Lai, Yong Han, James W. Evans, Patricia A. Thiel 2020 Iowa State University

Fundamentals Of Au(111) Surface Dynamics: Coarsening Of 2d Au Islands, Peter M. Spurgeon, King C. Lai, Yong Han, James W. Evans, Patricia A. Thiel

Chemistry Publications

Au(111) surfaces play a central role in many applications, yet studies of fundamental aspects of their dynamics are limited. Thus, using Scanning Tunneling Microscopy (STM) at 300 K, we analyze the coarsening of first-layer 2D Au islands directly on the Au(111) substrate, and also of second-layer 2D Au islands. Specifically, we monitor the decay of Au first-layer islands with areas of about 100-500 nm^2 in the vicinity of larger islands or extended step edges over a period of approximately 40 hours - the relevant time scale for this process. Experimentally observed behavior is captured by analytic theory for ...


Adsorption, Intercalation, Diffusion, And Adhesion Of Cu At The 2h−Mos2 (0001) Surface From First-Principles Calculations, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel 2020 Iowa State University and Ames Laboratory

Adsorption, Intercalation, Diffusion, And Adhesion Of Cu At The 2h−Mos2 (0001) Surface From First-Principles Calculations, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel

Chemistry Publications

Study of the adsorption of a transition metal on the surface of a layered material and the possible subsequent intercalation into that layered material is of fundamental interest and potential technological importance. In the present work, we choose the transition metal Cu as the adsorbate or intercalant and 2H-MoS2 as the layered material. Energetics are calculated characterizing four of the most basic surface and interfacial phenomena: adsorption, intercalation, diffusion, and adhesion. Using first-principles density functional theory (DFT), we find that intercalating a Cu atom into the van der Waals (vdW) gap below the MoS2 (0001) surface is 0.665 eV ...


Study Of Reaction Dynamics Of Protonated/Deprotonated And Radical Cations Of Guanine In Nucleobases And Nucleosides: Singlet Oxygen Oxidation, C8-Water Addition, Cross-Linking With Lysine And Base-Pair Dissociation, Yan Sun 2020 The Graduate Center, City University of New York

Study Of Reaction Dynamics Of Protonated/Deprotonated And Radical Cations Of Guanine In Nucleobases And Nucleosides: Singlet Oxygen Oxidation, C8-Water Addition, Cross-Linking With Lysine And Base-Pair Dissociation, Yan Sun

All Dissertations, Theses, and Capstone Projects

Among the four DNA nucleobases, guanine (G) has the lowest oxidation potential and represents a preferential target for oxidation and ionization. This leads to the formation of guanine radical cation (G•+) in various oxidative environments. Of the biologically relevant oxidants, electronically excited singlet oxygen (1O2) exclusively damages the guanine bases and gives rise to mutagenesis, DNA-protein cross-linking and cellular death. Combining our home-made electrospray ionization (ESI) guided-ion-beam tandem mass spectrometer, with reaction potential surface calculations and kinetics modeling, five projects have been accomplished as described below.

In project 1, the reactions of deuterated water (D2O) with ...


In Situ Monitoring Of Catalytic Molecular Transformations On Noble Metal Nanocatalysts Using Surface-Enhanced Raman Spectroscopy, Hui Wang, Qingfeng Zhang, Esteban Villarreal, Hao Jing, Kexun Chen 2020 University of South Carolina

In Situ Monitoring Of Catalytic Molecular Transformations On Noble Metal Nanocatalysts Using Surface-Enhanced Raman Spectroscopy, Hui Wang, Qingfeng Zhang, Esteban Villarreal, Hao Jing, Kexun Chen

Journal of the South Carolina Academy of Science

Noble metal nanoparticles have long been of tremendous interest in the nanophotonics and nanocatalysis communities owing to their intriguing size- and shape-dependent plasmonic and catalytic properties. The combination of tunable plasmon resonances with superior catalytic activities on the same noble metal nanoparticle, however, has long been challenging because the research on nanoplasmonics and nanocatalysis deals with nanoparticles in two drastically different size regimes. While tunable plasmon resonances are a unique feature of metallic nanoparticles in the sub-wavelength size regime, heterogeneous catalysis requires the use of substrate-supported sub-5 nm nanoparticulate catalysts. In this mini-review article, we share with the readers several ...


Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler 2020 Washington University in St. Louis

Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler

Electrical & Systems Engineering Publications and Presentations

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. Here, we report the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. The nanowires show significant heterogeneity along their lengths for the photocatalytic generation of hydroxyl radicals. Through quantitative, coordinate-based colocalization of multiple probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of ...


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