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Effects Of Biradical Deuteration On The Performance Of Dnp: Towards Better Performing Polarizing Agents, Frédéric A. Perras, Regina R. Reinig, Igor I. Slowing, Aaron D. Sadow, Marek Pruski 2019 Ames Laboratory

Effects Of Biradical Deuteration On The Performance Of Dnp: Towards Better Performing Polarizing Agents, Frédéric A. Perras, Regina R. Reinig, Igor I. Slowing, Aaron D. Sadow, Marek Pruski

Igor I. Slowing

We study the effects of the deuteration of biradical polarizing agents on the efficiency of dynamic nuclear polarization (DNP) via the cross-effect. To this end, we synthesized a series of bTbK and TOTAPol biradicals with systematically increased deuterium substitution. The deuteration increases the radicals' relaxation time, thus contributing to a higher saturation factor and larger DNP enhancement, and reduces the pool of protons within the so-called spin diffusion barrier. Notably, we report that full or partial deuteration leads to improved DNP enhancement factors in standard samples, but also slows down the build-up of hyperpolarization. Improvements in DNP enhancements factors of ...


Effects Of Biradical Deuteration On The Performance Of Dnp: Towards Better Performing Polarizing Agents, Frédéric A. Perras, Regina R. Reinig, Igor I. Slowing, Aaron D. Sadow, Marek Pruski 2019 Ames Laboratory

Effects Of Biradical Deuteration On The Performance Of Dnp: Towards Better Performing Polarizing Agents, Frédéric A. Perras, Regina R. Reinig, Igor I. Slowing, Aaron D. Sadow, Marek Pruski

Aaron D. Sadow

We study the effects of the deuteration of biradical polarizing agents on the efficiency of dynamic nuclear polarization (DNP) via the cross-effect. To this end, we synthesized a series of bTbK and TOTAPol biradicals with systematically increased deuterium substitution. The deuteration increases the radicals' relaxation time, thus contributing to a higher saturation factor and larger DNP enhancement, and reduces the pool of protons within the so-called spin diffusion barrier. Notably, we report that full or partial deuteration leads to improved DNP enhancement factors in standard samples, but also slows down the build-up of hyperpolarization. Improvements in DNP enhancements factors of ...


In Silico Design Of Dnp Polarizing Agents: Can Current Dinitroxides Be Improved?, Frédéric A. Perras, Aaron D. Sadow, Marek Pruski 2019 Ames Laboratory

In Silico Design Of Dnp Polarizing Agents: Can Current Dinitroxides Be Improved?, Frédéric A. Perras, Aaron D. Sadow, Marek Pruski

Aaron D. Sadow

Numerical calculations of enhancement factors offered by dynamic nuclear polarization in solids under magic angle spinning (DNP‐MAS) were performed to determine the optimal EPR parameters for a dinitroxide polarizing agent. We found that the DNP performance of a biradical is more tolerant to the relative orientation of the two nitroxide moieties than previously thought. Generally, any condition in which the gyy tensor components of both radicals are perpendicular to one another is expected to have near‐optimal DNP performance. Our results highlight the important role of the exchange coupling, which can lessen the sensitivity of DNP performance to the ...


Minimalistic Peptide-Based Supramolecular Systems Relevant To The Chemical Origin Of Life, Daniela Kroiss 2019 The Graduate Center, City University of New York

Minimalistic Peptide-Based Supramolecular Systems Relevant To The Chemical Origin Of Life, Daniela Kroiss

All Dissertations, Theses, and Capstone Projects

All forms of life are based on biopolymers, which are made up of a selection of simple building blocks, such as amino acids, nucleotides, fatty acids and sugars. Their individual properties govern their interactions, giving rise to complex supramolecular structures with highly specialized functionality, including ligand recognition, catalysis and compartmentalization. In this thesis, we aim to answer the question whether short peptides could have acted as precursors of modern proteins during prebiotic evolution. Using a combination of experimental and computational techniques, we screened a large molecular search space for peptide sequences that are capable of forming supramolecular complexes with adenosine ...


Synthesis And Characterization Of Multifunctional Transition Metal Oxide Nanoparticles Through A Modified Sol-Gel Method With Application In Energy Storage, Julien Lombardi 2019 The Graduate Center, City University of New York

Synthesis And Characterization Of Multifunctional Transition Metal Oxide Nanoparticles Through A Modified Sol-Gel Method With Application In Energy Storage, Julien Lombardi

All Dissertations, Theses, and Capstone Projects

The Synthesis of transition metal oxide nanoparticles has been studied in great detail over the many years. The most studied transition metal oxide nanoparticles are perovskites of the ABO3 stoichiometry (A and B = transition metal) and more recently double perovskite crystal structures of the AA’BO6 or A2BB’O6 stoichiometry due to the many different properties arising from the many different combinations of elements possible. These materials have proven potentially useful in many fields, but due to properties such as ferroelectricity and ferromagnetism, the desire to integrate these materials into electronics is ever growing. Many ...


Modeling Chemical Reactivity In Aqueous And Organic Systems: From Electronic Structure Methods To Force Field Development, Caitlin Gibson Bresnahan 2019 Louisiana State University and Agricultural and Mechanical College

Modeling Chemical Reactivity In Aqueous And Organic Systems: From Electronic Structure Methods To Force Field Development, Caitlin Gibson Bresnahan

LSU Doctoral Dissertations

Modeling reactivity in chemical systems has evolved dramatically in line with the capabilities of modern computing. Despite the advances in computational ability, the level in which one can model a system depends on a number of factors including the region of reactivity, size of the system, level of sophistication required in the molecular description, and so on. Electronic structure methods allow for a detailed description of the potential energy surface and inherently include all essential physics required for reactivity to occur, however these methods are limited by their computational expense. On the other hand, force fields allow for an atomistic ...


The Analysis Of Trifluoromethylbenzimidazole (Tfmbi) Crystals Using Physical Chemistry Techniques To Explain Ferroelectric And Anti-Ferroelectric Properties Of The Compound, Kanwar Bhullar 2019 Wayne State University

The Analysis Of Trifluoromethylbenzimidazole (Tfmbi) Crystals Using Physical Chemistry Techniques To Explain Ferroelectric And Anti-Ferroelectric Properties Of The Compound, Kanwar Bhullar

Honors College Theses

Ferroelectrics are a group of materials possessing the unique chemical property of being able to switch their electrical polarity when exposed to an electric field. This property makes ferroelectrics a promising field of study with the potential to impact various future technologies in information and energy storage, as well as quantum mechanics. Understanding molecular structures of ferroelectric (and opposite anti-ferroelectric) materials, and how they relate to the compound’s properties is essential to harnessing the potential these materials carry. The report discusses analysis of anti-ferroelectric material trifluoromethylbenzimidazole (TFMBI), by subjecting the compound to various physical and computational chemistry techniques at ...


Solid-State Nmr Of Co2 Mineralization And Nmr Crystallography, Jinlei Cui 2019 Washington University in St. Louis

Solid-State Nmr Of Co2 Mineralization And Nmr Crystallography, Jinlei Cui

Arts & Sciences Electronic Theses and Dissertations

The work described in this dissertation has been accomplished by using solid-state nuclear magnetic resonance (SSNMR) spectroscopy to investigate CO2 mineralization and to refine the positions of protons in the crystalline system. The reaction of forsterite (Mg2SiO4) and 13CO2 is presented here, which is measured using in-situ 13C NMR spectroscopy without removing the sample from the reactor. 29Si SSNMR is used to investigate the reaction of forsterite with 13CO2 in the presence of water or NaCl brine as a function of depth in the sample. Additionally, we also show that NMR crystallography can significantly improve structure refinement of hydrogens’ positions ...


Erratum: "Imaging The Three‐Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri‐Spot Point Spread Function", Oumeng Zhang, Jin Lu, Tianben Ding, Matthew D. Lew 2019 Washington University in St Louis

Erratum: "Imaging The Three‐Dimensional Orientation And Rotational Mobility Of Fluorescent Emitters Using The Tri‐Spot Point Spread Function", Oumeng Zhang, Jin Lu, Tianben Ding, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

In the original paper, a calibration error exists in the image-formation model used to analyze experimental images taken by our microscope, causing a bias in the orientation measurements in Figs. 2 and 3. The updated measurements are shown in Fig. E1. We have also updated the supplementary material for the original article to discuss the revised PSF model and estimation algorithms (supplementary material 2) and show the revised model and measurements (Figs. S1, S3, S7, S8, and S10–S13).


Computational Studies Of Thermal Properties And Desalination Performance Of Low-Dimensional Materials, Yang Hong 2019 University of Nebraska - Lincoln

Computational Studies Of Thermal Properties And Desalination Performance Of Low-Dimensional Materials, Yang Hong

Student Research Projects, Dissertations, and Theses - Chemistry Department

During the last 30 years, microelectronic devices have been continuously designed and developed with smaller size and yet more functionalities. Today, hundreds of millions of transistors and complementary metal-oxide-semiconductor cells can be designed and integrated on a single microchip through 3D packaging and chip stacking technology. A large amount of heat will be generated in a limited space during the operation of microchips. Moreover, there is a high possibility of hot spots due to non-uniform integrated circuit design patterns as some core parts of a microchip work harder than other memory parts. This issue becomes acute as stacked microchips get ...


Quantum Chemical Calculations Applied To Somo-Homo Conversion And Vibrationally Averaged Nmr Shielding Parameters, Erik Johnson 2019 University of Nebraska - Lincoln

Quantum Chemical Calculations Applied To Somo-Homo Conversion And Vibrationally Averaged Nmr Shielding Parameters, Erik Johnson

Student Research Projects, Dissertations, and Theses - Chemistry Department

The inversion of frontier orbitals of free radicals was studied using density functional theory calculations in Gaussian 09. Comparisons of images of orbitals in GaussView was used to assess the relative positions of singly occupied and doubly occupied orbitals and to determine which was the highest in energy. A variety of organic free radicals were studied including several radical anions and also a neutral radical. It was found that cross-conjugation appears to be a factor in whether or not molecules show SOMO-HOMO conversion. Cross-conjugation is when two unsaturated groups are conjugated to a third unsaturated group but are not conjugated ...


Computational Study On Binding Of Naturally Occurring Aromatic And Cyclic Amino Acids With Graphene, Dalia Daggag 2019 Clark Atlanta University

Computational Study On Binding Of Naturally Occurring Aromatic And Cyclic Amino Acids With Graphene, Dalia Daggag

Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University

The knowledge on the conformations of amino acids is essential to understand the biochemical behaviors and physical properties of proteins. Comprehensive computational study is focused to understand the conformational landscape of three aromatic amino acids (AAAs): tryptophan, tyrosine, and phenylalanine. Three different density functionals (B3LYP, M06-2X and wB97X-D) were used with two basis sets of 6-31G(d) and 6-31+G(d,p) for geometry optimizations of the conformers of AAAs followed by the vibrational frequencies. The goal was to identify the right choice of density functional theory (DFT) level for conformational analysis of amino acids by comparing the computational data ...


Stereodynamical Control Of A Quantum Scattering Resonance In Cold Molecular Collisions, Pablo G. Jambrina, James F.E. Croft, Hua Guo, Mark Brouard, Balakrishnan Naduvalath, F. Javier Aoiz 2019 Universidad de Salamanca

Stereodynamical Control Of A Quantum Scattering Resonance In Cold Molecular Collisions, Pablo G. Jambrina, James F.E. Croft, Hua Guo, Mark Brouard, Balakrishnan Naduvalath, F. Javier Aoiz

Chemistry and Biochemistry Faculty Publications

Cold collisions of light molecules are often dominated by a single partial wave resonance. For the rotational quenching of HD (v=1, j=2) by collisions with ground state para-H2, the process is dominated by a single L=2 partial wave resonance centered around 0.1 K. Here, we show that this resonance can be switched on or off simply by appropriate alignment of the HD rotational angular momentum relative to the initial velocity vector, thereby enabling complete control of the collision outcome.


High-Field Mas Dynamic Nuclear Polarization Using Radicals Created By Γ-Irradiation, Scott L. Carnahan, Amrit Venkatesh, Frederic A. Perras, James F. Wishart, Aaron J. Rossini 2019 Iowa State University and Ames Laboratory

High-Field Mas Dynamic Nuclear Polarization Using Radicals Created By Γ-Irradiation, Scott L. Carnahan, Amrit Venkatesh, Frederic A. Perras, James F. Wishart, Aaron J. Rossini

Chemistry Publications

High-field magic angle spinning dynamic nuclear polarization (MAS DNP) is often used to enhance the sensitivity of solid-state nuclear magnetic resonance (ssNMR) experiments by transferring spin polarization from electron spins to nuclear spins. Here, we demonstrate that γ-irradiation induces the formation of stable radicals in inorganic solids, such as fused quartz and borosilicate glasses as well as organic solids such as glucose, cellulose, and a urea/polyethylene polymer. The radicals were then used to polarize 29Si or 1H spins in the core of some of these materials. Significant MAS DNP enhancements (ε) greater than 400 and 30 were obtained for ...


Synchrotron Radiation Analysis Of Daguerreotypes: Surface Characterization, Electrocleaning, And Preservation, Madalena S. Kozachuk 2019 The University of Western Ontario

Synchrotron Radiation Analysis Of Daguerreotypes: Surface Characterization, Electrocleaning, And Preservation, Madalena S. Kozachuk

Electronic Thesis and Dissertation Repository

The first commercially viable photographic image, the daguerreotype, captured images from 1839 to 1860. While daguerreotypes provide a significant historical record of 19th century individuals and events, deterioration now disfigures many of these images. This work describes the application of synchrotron radiation (SR) to the study of daguerreotypes.

Three goals were addressed in this thesis: 1) to utilize SR to further elucidate the physics and chemistry of the daguerreotype and how the surface varies with time, 2) to study the effects of the electrocleaning system on the daguerreotype surface, and 3) to propose suggestions to improve their preservation and ...


Using Forensics To Introduce Ir Spectroscopy & Molecular Modeling, Joe Golab 2019 Illinois Mathematics and Science Academy

Using Forensics To Introduce Ir Spectroscopy & Molecular Modeling, Joe Golab

Faculty Publications & Research

A student activity is reported that analyzes “medical evidence” with experimental and computational methods. The lesson demonstrates benefits of solving practical problems with integrated tools.


Using Molecular Dynamics To Study Qs21 Interactions And Penetration Of Lipid-Cholesterol Bilayers, Sarai Guerrero, Mikko Karttunen 2019 The University of Western Ontario

Using Molecular Dynamics To Study Qs21 Interactions And Penetration Of Lipid-Cholesterol Bilayers, Sarai Guerrero, Mikko Karttunen

Western Research Forum

Saponins have been used as adjuvant agents for decades in vaccines and therapies, but none are as well studied or heavily used as QS-21. This achievement is notwithstanding the fact that QS-21 usage is limited by its stability, toxicity, and scarcity. These shortcomings have only pushed researchers to develop and experiment with artificial recreations of the saponin to harness its unique benefits. A considerable number of research hours have been poured into this topic, but like QS-21 there is a shortcoming here as well. The number of articles that look at QS-21 interactions with the bilayer or the conditions under ...


Triplet Population Dynamics And Excited State Relaxation In Chalcogenophene Polymers, Benjamin D. Datko 2019 University of New Mexico - Main Campus

Triplet Population Dynamics And Excited State Relaxation In Chalcogenophene Polymers, Benjamin D. Datko

Chemistry ETDs

The conventional understanding of intersystem crossing in multichromophoric conju- gated polymers is usually depicted via a pure electronic model, neglecting contributions of vibrations or conformational order. Obtaining accurate structure-function correlations on spin-conversion processes involving photogenerated singlet excitons to triplet excitons and the excited state dynamics requires sensitivity to the subtle conformational ordering within conjugated polymers. This dissertation seeks to understand the kinetics of multi-exciton singlet-triplet interactions and the excited state relaxation of chalcogen containing (S, Se) conjugated polymers. Utilizing single molecule modulation spectroscopy allows determi- nation of triplet formation of individual conjugated polymer chains and aggregates. This technique resolves triplet-induced ...


The Spectroscopic And Computational Exploration Of Sulfur Hydrogen Bonding, Andrew Yoonkeun Lee 2019 Seattle Pacific University

The Spectroscopic And Computational Exploration Of Sulfur Hydrogen Bonding, Andrew Yoonkeun Lee

Honors Projects

Hydrogen bonds are a subset of non-covalent interactions that occur between X-H — Y, in which X and Y are the very electronegative atoms. In our research, we examine the more unconventional hydrogen bond-like interactions of thiol (SH) containing molecules using vapor-phase infrared (IR) spectroscopy and ab initio computational chemistry. When the SH hydrogen bond donor complexes to a hydrogen bond acceptor, a red shift of the SH stretching mode emerges. An anharmonic oscillator local mode model is applied to the ethanethiol-trimethylamine dimer, and we determine that any IR evidence of dimerization in our experiment is likely obscured by the asymmetric ...


Ab Initio Calculations Of Changes In Sulfur’S Orbital Energies And Sizes With Oxidation State As A Means Of Explaining Hypervalency, Anton V. Taraskin 2019 Seattle Pacific University

Ab Initio Calculations Of Changes In Sulfur’S Orbital Energies And Sizes With Oxidation State As A Means Of Explaining Hypervalency, Anton V. Taraskin

Honors Projects

The energetics and orbital sizes of sulfur’s valence 3d and fluorine’s valence 2p orbitals were measured using a closed active space self-consistent field calculation to determine the degree of possible bonding available to sulfur’s 3d. It was determined that for orbital energies, the cc-pVXZ and aug sets converged hyperbolically onto a single energy value as X increased and that for both fluorine and sulfur orbital energies scaled down linearly with oxidation state. This resulted in a 0.47 hartree difference between the sulfur 3d and fluorine 2p orbitals at S0.6+ and F-0.1, far exceeding the ...


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