Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 19 of 19

Full-Text Articles in Physical Sciences and Mathematics

Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, Suwit Suthirakun, Salai Cheettu Ammal, Guoliang Xiao, Fanglin Chen, Andreas Heyden, Hans-Conrad Zur Loye Nov 2011

Density Functional Theory Study On The Electronic Structure Of N- And P-Type Doped Srtio3 At Anodic Solid Oxide Fuel Cell Conditions, Suwit Suthirakun, Salai Cheettu Ammal, Guoliang Xiao, Fanglin Chen, Andreas Heyden, Hans-Conrad Zur Loye

Faculty Publications

The electronic conductivity and thermodynamic stability of mixed n-type and p-type doped SrTiO3 have been investigated at anodic solid oxide fuel cell (SOFC) conditions using density functional theory (DFT) calculations. In particular, constrained ab initio thermodynamic calculations have been performed to evaluate the phase stability and reducibility of various Nb- and Ga-doped SrTiO3 at synthesized and anodic SOFC conditions. The density of states (DOS) of these materials was analyzed to study the effects of n- and p-doping on the electronic conductivity. In agreement with experimental observations, we find that the transformation from 20% Nb-doped Sr-deficient SrTiO …


Preparation Of Novel Hydrolyzing Urethane Modified Thiol-Ene Networks, Nicole M. Mackey, Bridget S. Confait, James Wynne, J. Paige Buchanan Oct 2011

Preparation Of Novel Hydrolyzing Urethane Modified Thiol-Ene Networks, Nicole M. Mackey, Bridget S. Confait, James Wynne, J. Paige Buchanan

Faculty Publications

Novel tetra-functional hydrolyzing monomers were prepared from the reaction of TEOS and select alkene-containing alcohols, ethylene glycol vinyl ether or 2-allyloxy ethanol, and combined with trimethylolpropane tris(3-mercaptopropionate) (tri-thiol) in a thiol-ene “click” polymerization reaction to produce clear, colorless thiol-ene networks using both radiation and thermal-cure techniques. These networks were characterized for various mechanical characteristics, and found to posses Tg’s (DSC), hardness, tack, and thermal stability (TGA) consistent with their molecular structures. A new ene-modified urethane oligomer was prepared based on the aliphatic polyisocyanate Desmodur® N 3600 and added to the thiol-ene hydrolyzable network series in increasing amounts, …


Vibrational And Electronic Spectra Of 9, 10-Dihydrobenzo (A) Pyren-7 (8h)-One And 7, 8, 9, 10-Tetrahydrobenzo (A) Pyrene: An Experimental And Computational Study [Abstract], Kefa Karimu Onchoke, Prabir K. Dutta, Matthew Parks, Mireya Martinez Oct 2011

Vibrational And Electronic Spectra Of 9, 10-Dihydrobenzo (A) Pyren-7 (8h)-One And 7, 8, 9, 10-Tetrahydrobenzo (A) Pyrene: An Experimental And Computational Study [Abstract], Kefa Karimu Onchoke, Prabir K. Dutta, Matthew Parks, Mireya Martinez

Faculty Publications

No abstract provided.


A Modified Stokes-Einstein Equation For A Beta Aggregation, Srisairam Achuthan, Bong Jae Chung, Preetam Ghosh, Vijayaraghavan Rangachari, Ashwin Vaidya Oct 2011

A Modified Stokes-Einstein Equation For A Beta Aggregation, Srisairam Achuthan, Bong Jae Chung, Preetam Ghosh, Vijayaraghavan Rangachari, Ashwin Vaidya

Faculty Publications

Background: In all amyloid diseases, protein aggregates have been implicated fully or partly, in the etiology of the disease. Due to their significance in human pathologies, there have been unprecedented efforts towards physiochemical understanding of aggregation and amyloid formation over the last two decades. An important relation from which hydrodynamic radii of the aggregate is routinely measured is the classic Stokes-Einstein equation. Here, we report a modification in the classical Stokes-Einstein equation using a mixture theory approach, in order to accommodate the changes in viscosity of the solvent due to the changes in solute size and shape, to implement a …


The Regulation Of Skeletal Muscle Protein Turnover During The Progression Of Cancer Cachexia In The ApcMin/+ Mouse, James P. White, John W. Baynes, Stephen L. Welle, Matthew C. Kostek, Lydia E. Matesic, Shuichi Sato, James A. Carson Sep 2011

The Regulation Of Skeletal Muscle Protein Turnover During The Progression Of Cancer Cachexia In The ApcMin/+ Mouse, James P. White, John W. Baynes, Stephen L. Welle, Matthew C. Kostek, Lydia E. Matesic, Shuichi Sato, James A. Carson

Faculty Publications

Muscle wasting that occurs with cancer cachexia is caused by an imbalance in the rates of muscle protein synthesis and degradation. The Apc(Min/+) mouse is a model of colorectal cancer that develops cachexia that is dependent on circulating IL-6. However, the IL-6 regulation of muscle protein turnover during the initiation and progression of cachexia in the Apc(Min/+) mouse is not known. Cachexia progression was studied in Apc(Min/+) mice that were either weight stable (WS) or had initial (≤5%), intermediate (6-19%), or extreme (≥20%) body weight loss. The initiation of cachexia reduced %MPS 19% and a further ∼50% with additional weight …


Experimental And Theoretical Study Of Vibrational Spectra Of 3-Nitrofluoranthene [Abstract], Kefa Karimu Onchoke, Matthew Parks Jul 2011

Experimental And Theoretical Study Of Vibrational Spectra Of 3-Nitrofluoranthene [Abstract], Kefa Karimu Onchoke, Matthew Parks

Faculty Publications

No abstract provided.


Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, James Mazzuca, Tijo Vazhappilly Jul 2011

Efficient Quantum Trajectory Representation Of Wavefunctions Evolving In Imaginary Time, Sophya V. Garashchuk, James Mazzuca, Tijo Vazhappilly

Faculty Publications

The Boltzmann evolution of a wavefunction can be recast as imaginary-time dynamics of the quantum trajectory ensemble. The quantum effects arise from the momentum-dependent quantum potential – computed approximately to be practical in high-dimensional systems – influencing the trajectories in addition to the external classical potential [S. Garashchuk, J. Chem. Phys.132, 014112 (2010)]. For a nodelesswavefunction represented as ψ(x, t) = exp ( − S(x, t)/ℏ) with the trajectory momenta defined by ∇S(x, t), analysis of the Lagrangian and Eulerian evolution shows that for bound potentials the former …


Using Nanotechnology To Detect Nerve Agents, Mark N. Goltz, Dong-Shik Kim, Leeann Racz Jul 2011

Using Nanotechnology To Detect Nerve Agents, Mark N. Goltz, Dong-Shik Kim, Leeann Racz

Faculty Publications

Nanotechnology has opened a wide range of opportunities having potential impacts in areas as diverse as medicine and consumer products. In collaboration with researchers at the University of Toledo UT, Air Force Institute of Technology AFIT scientists are exploring the possibility of using a nanoscale organic matrix to detect organophosphate OP nerve agents. Current techniques for detecting OP compounds are expensive and time consuming. Developing a nanoscale organic matrix sensor would allow for direct, real-time sensing under field conditions. This article describes the science behind such a sensor and its possible applications. High-performance sensors are needed to protect Soldiers and …


Thiolene-Based Microfluidic Flow Cells For Surface Plasmon Resonance Imaging, Gareth Sheppard, Takao Oseki, Akira Baba, Derek L. Patton, Futao Kaneko, Leidong Mao, Jason Locklin Jun 2011

Thiolene-Based Microfluidic Flow Cells For Surface Plasmon Resonance Imaging, Gareth Sheppard, Takao Oseki, Akira Baba, Derek L. Patton, Futao Kaneko, Leidong Mao, Jason Locklin

Faculty Publications

Thiolene-based microfluidic devices have been coupled with surface plasmon resonance imaging (SPRI) to provide an integrated platform to study interfacial interactions in both aqueous and organic solutions. In this work, we develop a photolithographic method that interfaces commercially available thiolene resin to gold and glass substrates to generate microfluidic channels with excellent adhesion that leave the underlying sensor surface free from contamination and readily available for surface modification through self-assembly. These devices can sustain high flow rates and have excellent solvent compatibility even with several organic solvents. To demonstrate the versatility of these devices, we have conducted nanomolar detection of …


A Bis-Urea Naphthalene Macrocycle Displaying Two Crystal Structures With Parallel Ureas, Michael F. Geer, Mark D. Smith, Linda S. Shimizu Apr 2011

A Bis-Urea Naphthalene Macrocycle Displaying Two Crystal Structures With Parallel Ureas, Michael F. Geer, Mark D. Smith, Linda S. Shimizu

Faculty Publications

Herein we synthesized a bis-urea macrocycle from 2,7-dimethylnaphthalene that displays an unusual parallel urea conformation. The naphthalenes also adopt a bowl shape over the anticipated parallel planar orientation. Crystallization of the macrocycle from different solvent systems affords two solvated forms. 1·DMSO·(H2O)2 has an extended columnar structure where parallel macrocycles are linked by intervening hydrogen bonded water molecules. In 1·(MeOH)2direct hydrogen-bonds link the macrocycles into chains, which hydrogen-bond with methanolmolecules to form a layered structure.


Non-Esterified Fatty Acids Generate Distinct Low-Molecular Weight Amyloid-Β (Aβ42) Oligomers Along Pathway Different From Fibril Formation, Amit Kumar, Rebekah L. Bullard, Pritesh Patel, Lea C. Paslay, Dipti Singh, Ewa A. Bienkiewicz, Sarah E. Morgan, Vijayaraghavan Rangachari Apr 2011

Non-Esterified Fatty Acids Generate Distinct Low-Molecular Weight Amyloid-Β (Aβ42) Oligomers Along Pathway Different From Fibril Formation, Amit Kumar, Rebekah L. Bullard, Pritesh Patel, Lea C. Paslay, Dipti Singh, Ewa A. Bienkiewicz, Sarah E. Morgan, Vijayaraghavan Rangachari

Faculty Publications

Amyloid-beta (A beta) peptide aggregation is known to play a central role in the etiology of Alzheimer's disease (AD). Among various aggregates, low-molecular weight soluble oligomers of A beta are increasingly believed to be the primary neurotoxic agents responsible for memory impairment. Anionic interfaces are known to influence the A beta aggregation process significantly. Here, we report the effects of interfaces formed by medium-chain (C9-C12), saturated non-esterified fatty acids (NEFAs) on A beta 42 aggregation. NEFAs uniquely affected A beta 42 aggregation rates that depended on both the ratio of A beta:NEFA as well the critical micelle concentration (CMC) of …


Electrospinning Fabrication, Structural And Mechanical Characterization Of Rod-Like Virus-Based Composite Nanofibers, Laying Wu, Jianfeng Zang, L. Andrew Lee, Zhongwei Niu, Gary C. Horvatha, Vaughn Braxtona, Arief C. Wibowo, Michael A. Bruckman, Soumitra Ghoshroy, Hans-Conrad Zur Loye, Xiaodong Li, Qian Wang Mar 2011

Electrospinning Fabrication, Structural And Mechanical Characterization Of Rod-Like Virus-Based Composite Nanofibers, Laying Wu, Jianfeng Zang, L. Andrew Lee, Zhongwei Niu, Gary C. Horvatha, Vaughn Braxtona, Arief C. Wibowo, Michael A. Bruckman, Soumitra Ghoshroy, Hans-Conrad Zur Loye, Xiaodong Li, Qian Wang

Faculty Publications

Tobacco mosaic virus (TMV) was electrospun with polyvinyl alcohol (PVA) into continuous TMV–PVA composite nanofibers to form a biodegradable nonwoven fibrous mat as an extracellular matrix (ECM) mimetic. Morphological characterizations by electron microscopyshowed that the addition of varying amounts of TMV resulted in homogeneous nanofibers without phase separation and did not change the diameter of the composite nanofibers. The orientation of TMV in as-spun fibers could be readily controlled and post-processing of the nonwoven TMV–PVA mat significantly improved its water resistance. In addition, tensile tests were performed on individual nanofibers, which revealed that the TMV–PVA composite nanofibers achieved a comparable …


Thiol-Yne 'Click' Chemistry As A Route To Functional Lipid Mimetics, Sandeep S. Naik, Justin W. Chan, Christopher Comer, Charles E. Hoyle, Daniel A. Savin Jan 2011

Thiol-Yne 'Click' Chemistry As A Route To Functional Lipid Mimetics, Sandeep S. Naik, Justin W. Chan, Christopher Comer, Charles E. Hoyle, Daniel A. Savin

Faculty Publications

Thiol-alkyne 'click' chemistry is a modular, efficient mechanism to synthesize complex A2B 3-arm star polymers. This general motif is similar to a phospholipid where the A blocks correspond to lypophilic chains and the B block represents the polar head group. In this communication we employ thiol-yne chemistry to produce polypeptide-based A2B lipid mimetics. The utility of the thiol-yne reaction is demonstrated by using a divergent and a convergent approach in the synthesis. These polymers self-assemble in aqueous solution into spherical vesicles with a relatively narrow size distribution independent of block composition over the range studied. Using …


Photosensitizer Drug Delivery Via An Optical Fiber, Matibur Zamadar, Goutam Ghosh, Adaic Kapillai Mahendran, Mihaela Minnis, Bonnie I. Kruft, Ashwini Ghogare, David Aebisher, Alexander Greer Jan 2011

Photosensitizer Drug Delivery Via An Optical Fiber, Matibur Zamadar, Goutam Ghosh, Adaic Kapillai Mahendran, Mihaela Minnis, Bonnie I. Kruft, Ashwini Ghogare, David Aebisher, Alexander Greer

Faculty Publications

: An optical fiber has been developed with a maneuverable miniprobe tip that sparges O2 gas and photodetaches pheophorbide (sensitizer) molecules. Singlet oxygen is produced at the probe tip surface which reacts with an alkene spacer group releasing sensitizer upon fragmentation of a dioxetane intermediate. Optimal sensitizer photorelease occurred when the probe tip was loaded with 60 nmol sensitizer, where crowding of the pheophorbide molecules and self-quenching were kept to a minimum. The fiber optic tip delivered pheophorbide molecules and singlet oxygen to discrete locations. The 60 nmol sensitizer was delivered into petrolatum; however, sensitizer release was less efficient in …


Dft/Td-Dft Investigation Of Optical Absorption Spectra, Electron Affinities, And Ionization Potentials Of Mono-Nitrated Benzanthrones [Abstract], Kefa Karimu Onchoke Jan 2011

Dft/Td-Dft Investigation Of Optical Absorption Spectra, Electron Affinities, And Ionization Potentials Of Mono-Nitrated Benzanthrones [Abstract], Kefa Karimu Onchoke

Faculty Publications

No abstract provided.


Incremental Binding Energies Of Gold (I) And Silver (I) Thiolate Clusters, Brian M. Barngrover, Christine M. Aikens Jan 2011

Incremental Binding Energies Of Gold (I) And Silver (I) Thiolate Clusters, Brian M. Barngrover, Christine M. Aikens

Faculty Publications

Density functional theory is used to find incremental fragmentation energy, overall dissociation energy, and average monomer fragmentation energy of cyclic gold(I) thiolate clusters and anionic chain structures of gold(I) and silver(I) thiolate clusters as a measure of the relative stability of these systems. Two different functionals, BP86 and PBE, and two different basis sets, TZP and QZ4P, are employed. Anionic chains are examined with various residue groups including hydrogen, methyl, and phenyl. Hydrogen and methyl are shown to have approximately the same binding energy, which is higher than phenyl. Gold–thiolate clusters are bound more strongly than corresponding silver clusters. Lastly, …


Electron And Hydride Addition To Gold (I) Thiolate Oligomers: Implications For Gold–Thiolate Nanoparticle Growth Mechanisms, Brian M. Barngrover, Christine M. Aikens Jan 2011

Electron And Hydride Addition To Gold (I) Thiolate Oligomers: Implications For Gold–Thiolate Nanoparticle Growth Mechanisms, Brian M. Barngrover, Christine M. Aikens

Faculty Publications

Electron and hydride addition to Au(I):SR oligomers is investigated using density functional theory. Cyclic and chain-like clusters are examined in this work. Dissociation to Au ions and Aun(SR)n+1 chains is observed after 2–4 electrons are added to these systems. The free thiolate (SR) is rarely produced in this work; dissociation of Au is preferred over dissociation of SR. Electron affinities calculated in gas phase, toluene, and water suggest that the electron addition process is unlikely, although it may be possible in polar solvents. In contrast, hydride addition to Au(I):SR …


Analysis Of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission, Alyssa Frey, Nicholas Wozniak, Timothy Nagi, Matthew Keller, J. Mark Lunderberg, Graham F. Peaslee, Paul Deyoung, Jennifer R. Hampton Jan 2011

Analysis Of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission, Alyssa Frey, Nicholas Wozniak, Timothy Nagi, Matthew Keller, J. Mark Lunderberg, Graham F. Peaslee, Paul Deyoung, Jennifer R. Hampton

Faculty Publications

The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100mM NiSO4, 10 mM FeSO4, 0.5M H3BO3, and 1M Na2SO4 solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is …


Diffusion And Random Walks, Lewis Ludwig, Annabel Edwards Jan 2011

Diffusion And Random Walks, Lewis Ludwig, Annabel Edwards

Faculty Publications

No abstract provided.