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Articles 451 - 480 of 939
Full-Text Articles in Chemistry
Separation And Liquid Chromatography Using A Single Carbon Nanotube, Riju Singhal, Vadym Mochalin, Maria R. Lukatskaya, Gary Friedman, Yury G. Gogotsi
Separation And Liquid Chromatography Using A Single Carbon Nanotube, Riju Singhal, Vadym Mochalin, Maria R. Lukatskaya, Gary Friedman, Yury G. Gogotsi
Chemistry Faculty Research & Creative Works
Use of a single template-grown carbon nanotube as a separation column to separate attoliter volumes of binary mixtures of fluorescent dyes has been demonstrated. The cylindrical nanotube walls are used as stationary phase and the surface area is increased by growing smaller multi-walled carbon nanotubes within the larger nanotube column. Liquid-liquid extraction is performed to separate selectively soluble solutes in a solvent, and chromatographic separation is demonstrated using thin, long nanotubes coated inside with iron oxide nanoparticles. The setup is also used to determine the diffusion coefficient of a solute at the sub-micrometer scale. This study opens avenues for analytical …
Monitoring The Reductive And Oxidative Half-Reactions Of A Flavin-Dependent Monooxygenase Using Stopped-Flow Spectrophotometry., Elvira Romero, Reeder Robinson, Pablo Sobrado
Monitoring The Reductive And Oxidative Half-Reactions Of A Flavin-Dependent Monooxygenase Using Stopped-Flow Spectrophotometry., Elvira Romero, Reeder Robinson, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Aspergillus fumigatus siderophore A (SidA) is an FAD-containing monooxygenase that catalyzes the hydroxylation of ornithine in the biosynthesis of hydroxamate siderophores that are essential for virulence (e.g. ferricrocin or N", N'''-triacetylfusarinine C). The reaction catalyzed by SidA can be divided into reductive and oxidative half-reactions. In the reductive half-reaction, the oxidized FAD bound to Af SidA, is reduced by NADPH. In the oxidative half-reaction, the reduced cofactor reacts with molecular oxygen to form a C4a-hydroperoxyflavin intermediate, which transfers an oxygen atom to ornithine. Here, we describe a procedure to measure the rates and detect the different spectral forms of SidA …
Investigation Of Polyurea-Crosslinked Silica Aerogels As A Neuronal Scaffold: A Pilot Study, Firouzeh Sabri, Judith A. Cole, M. Cody Scarbrough, Nicholas Leventis
Investigation Of Polyurea-Crosslinked Silica Aerogels As A Neuronal Scaffold: A Pilot Study, Firouzeh Sabri, Judith A. Cole, M. Cody Scarbrough, Nicholas Leventis
Chemistry Faculty Research & Creative Works
Background: Polymer crosslinked aerogels are an attractive class of materials for future implant applications particularly as a biomaterial for the support of nerve growth. The low density and nano-porous structure of this material combined with large surface area, high mechanical strength, and tunable surface properties, make aerogels materials with a high potential in aiding repair of injuries of the peripheral nervous system. However, the interaction of neurons with aerogels remains to be investigated. Methodology: In this work the attachment and growth of neurons on clear polyurea crosslinked silica aerogels (PCSA) coated with: poly-L-lysine, basement membrane extract (BME), and laminin1 was …
Histological Evaluation Of The Biocompatibility Of Polyurea Crosslinked Silica Aerogel Implants In A Rat Model: A Pilot Study, Firouzeh Sabri, J. D. Boughter Jr., D. Gerth, O. Skalli, T. C. N. Phung, G. R. M. Tamula, Nicholas Leventis
Histological Evaluation Of The Biocompatibility Of Polyurea Crosslinked Silica Aerogel Implants In A Rat Model: A Pilot Study, Firouzeh Sabri, J. D. Boughter Jr., D. Gerth, O. Skalli, T. C. N. Phung, G. R. M. Tamula, Nicholas Leventis
Chemistry Faculty Research & Creative Works
Background: Aerogels are a versatile group of nanostructured/nanoporous materials with physical and chemical properties that can be adjusted to suit the application of interest. In terms of biomedical applications, aerogels are particularly suitable for implants such as membranes, tissue growth scaffolds, and nerve regeneration and guidance inserts. The mesoporous nature of aerogels can also be used for diffusion based release of drugs that are loaded during the drying stage of the material. From the variety of aerogels polyurea crosslinked silica aerogels have the most potential for future biomedical applications and are explored here. Methodology: This study assessed the short and …
N-Acetyl-L-Cysteine Amide Protects Retinal Pigment Epithelium Against Methamphetamine-Induced Oxidative Stress, Nuran Ercal, Joshua W. Carey, Shakila Tobwala, Xinsheng Zhang, Atrayee Banerjee, Eylem Y. Pinarci, Humeyra Karacal
N-Acetyl-L-Cysteine Amide Protects Retinal Pigment Epithelium Against Methamphetamine-Induced Oxidative Stress, Nuran Ercal, Joshua W. Carey, Shakila Tobwala, Xinsheng Zhang, Atrayee Banerjee, Eylem Y. Pinarci, Humeyra Karacal
Chemistry Faculty Research & Creative Works
Methamphetamine (METH), a highly addictive drug used worldwide, induces oxidative stress in various animal organs. Recent animal studies indicate that methamphetamine also induces oxidative stress in the retina, which is an em- bryonic extension of the forebrain. The aim of this study, therefore, was to evaluate the pro- tecttive effects of N-acetylcysteine amide (NACA) against oxidative stress induced by METH in retinal pigment epithelium (RPE) cells. Our stud- ies showed that NACA protected against METH- induced oxidative stress in retinal pigment epithelial cells. Although METH significantly de- creased glutathione (GSH) levels and increased reactive oxygen species (ROS) and malondial- dehyde …
Noncanonical Reactions Of Flavoenzymes, Pablo Sobrado
Noncanonical Reactions Of Flavoenzymes, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetone phosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base …
Interstaple Dithiol Cross-Linking In Au 25(Sr) 18 Nanomolecules: A Combined Mass Spectrometric And Computational Study, Vijay Reddy Jupally, Rajesh Kota, Eric Van Dornshuld, Daniell L. Mattern, Gregory S. Tschumper, De En Jiang, Amala Dass
Interstaple Dithiol Cross-Linking In Au 25(Sr) 18 Nanomolecules: A Combined Mass Spectrometric And Computational Study, Vijay Reddy Jupally, Rajesh Kota, Eric Van Dornshuld, Daniell L. Mattern, Gregory S. Tschumper, De En Jiang, Amala Dass
Chemistry Faculty Research & Creative Works
A systematic study of cross-linking chemistry of the Au 25(SR) 18 nanomolecule by dithiols of varying chain length, HS-(CH2)n-SH where n = 2, 3, 4, 5, and 6, is presented here. Monothiolated Au25 has six [RSAuSRAuSR] staple motifs on its surface, and MALDI mass spectrometry data of the ligand exchanged clusters show that propane (C3) and butane (C4) dithiols have ideal chain lengths for interstaple cross-linking and that up to six C3 or C4 dithiols can be facilely exchanged onto the cluster surface. Propanedithiol predominately exchanges with two monothiols at a time, making cross-linking bridges, …
Structures, Energetics And Vibrational Frequency Shifts Of Hydrated Pyrimidine, J. Coleman Howard, Nathan I. Hammer, Gregory S. Tschumper
Structures, Energetics And Vibrational Frequency Shifts Of Hydrated Pyrimidine, J. Coleman Howard, Nathan I. Hammer, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
More than 70 unique micro-hydrated structures of pyrimidine, ranging in size from 1 to 7 water molecules, have been characterized with the B3LYP density functional and the 6-311++G(2df,2pd) triple-ζ split-valence basis set. Explicitly correlated MP2-F12 single-point computations were performed on each structure with a correlation consistent triple-ζ basis set to estimate the relative and dissociation energies at the MP2 complete basis set (CBS) limit. Many of these new structures have significantly lower energies than those previously reported (by as much as 12.66 kcal mol-1). For clusters with 1 and 2 water molecules, the MP2-F12 relative and dissociation energies are virtually …
C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay
C(Naphthyl)-H Bond Activation By Rhodium: Isolation, Characterization And Td-Dft Study Of The Cyclometallates, Achintesh Narayan Biswas, Purak K. Das, Sandip K. Sengupta, Amitava Choudhury, Pinaki K. Bandyopadhyay
Chemistry Faculty Research & Creative Works
The C1(naphthyl)-H, C2(naphthyl)-H, C3(naphthyl)-H and C8(naphthyl)-H bonds of the naphthyl group present in a group of naphthylazo-2'-hydroxyarenes (H 2L) have been activated by [Rh(PPh 3) 3Cl] in a toluene medium. Here the cyclometallation is accompanied by metal centered oxidation [Rh(i)?Rh(iii)]. All the resulting cyclometallates [Rh(PPh 3) 2(L)Cl] (2-5) have been isolated in a pure form. The characterization of the cyclometallates [Rh(PPh 3) 2(L)Cl] have been done on the basis of spectral (IR, UV-vis, and FAB mass) data. The structures of the representative cyclometallates 2a, 3a, 4a, 4b and 5b have been determined by …
Substrate Binding Modulates The Activity Of Mycobacterium Smegmatis G, A Flavin-Dependent Monooxygenase Involved In The Biosynthesis Of Hydroxamate-Containing Siderophores, Reeder Robinson, Pablo Sobrado
Substrate Binding Modulates The Activity Of Mycobacterium Smegmatis G, A Flavin-Dependent Monooxygenase Involved In The Biosynthesis Of Hydroxamate-Containing Siderophores, Reeder Robinson, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Mycobacterium smegmatis G (MbsG) is a flavin-dependent monooxygenase that catalyzes the NAD(P)H- and oxygen-dependent hydroxylation of the terminal amino group on the side chain of l-lysine in the biosynthetic pathway of the siderophore mycobactin. Mycobactins are essential for mycobacterium growth under iron-limiting conditions encountered during infection in mammals. Thus, enzymes involved in the biosynthesis of mycobactin represent potential drug targets. MbsG was expressed in Escherichia coli and purified using metal affinity and ionic exchange chromatographies. Recombinant MbsG represents the first member of this class of enzymes isolated in the active form, with a tightly bound FAD cofactor. The k cat …
Cloudy And Starry Milia-Like Cysts: How Well Do They Distinguish Seborrheic Keratoses From Malignant Melanomas?, S. M. Stricklin, William V. Stoecker, M. C. Oliviero, H. S. Rabinovitz, S. K. Mahajan
Cloudy And Starry Milia-Like Cysts: How Well Do They Distinguish Seborrheic Keratoses From Malignant Melanomas?, S. M. Stricklin, William V. Stoecker, M. C. Oliviero, H. S. Rabinovitz, S. K. Mahajan
Chemistry Faculty Research & Creative Works
Background Seborrheic keratoses are the most common skin lesions known to contain small white or yellow structures called milia-like cysts (MLCs). Varied appearances can sometimes make it difficult to differentiate benign lesions from malignant lesions such as melanoma, the deadliest form of skin cancer found in humans. Objective the purpose of this study was to determine the statistical occurrence of MLCs in benign vs. malignant lesions. Methods a medical student with 10 months experience in examining approximately 1000 dermoscopy images and a dermoscopy-naïve observer analyzed contact non-polarized dermoscopy images of 221 malignant melanomas and 175 seborrheic keratoses for presence of …
Accurate Interaction Energies For Problematic Dispersion-Bound Complexes: Homogeneous Dimers Of Nccn, P2, And Pccp, Edward G. Hohenstein, Heather M. Jaeger, Emily J. Carrell, Gregory S. Tschumper, C. David Sherrill
Accurate Interaction Energies For Problematic Dispersion-Bound Complexes: Homogeneous Dimers Of Nccn, P2, And Pccp, Edward G. Hohenstein, Heather M. Jaeger, Emily J. Carrell, Gregory S. Tschumper, C. David Sherrill
Chemistry Faculty Research & Creative Works
All intermolecular interactions involve London dispersion forces. The accurate treatment of dispersion is essential for the computation of realistic interaction potentials. In general, the most reliable method for computing intermolecular interactions is coupled-cluster singles and doubles with perturbative triples [CCSD(T)] in conjunction with a sufficiently flexible Gaussian atomic orbital basis set, a combination which is not routinely applicable due to its excessive computational demands (CPU time, memory, storage). Recently, many theoretical methods have been developed that attempt to account for dispersion in a more efficient manner. It is well-known that dispersion interactions are more difficult to compute in some systems …
Efficient And Accurate Methods For The Geometry Optimization Of Water Clusters: Application Of Analytic Gradients For The Two-Body:Many-Body Qm:Qm Fragmentation Method To (H2o)N, N = 3-10, Desiree M. Bates, Joshua R. Smith, Gregory S. Tschumper
Efficient And Accurate Methods For The Geometry Optimization Of Water Clusters: Application Of Analytic Gradients For The Two-Body:Many-Body Qm:Qm Fragmentation Method To (H2o)N, N = 3-10, Desiree M. Bates, Joshua R. Smith, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
The structures of more than 70 low-lying water clusters ranging in size from (H2O)3 to (H2O)10 have been fully optimized with several different quantum mechanical electronic structure methods, including second-order Møller-Plesset perturbation theory (MP2) in conjunction with correlation consistent triple-ζ basis sets (aug-cc-pVTZ for O and cc-pVTZ for H, abbreviated haTZ). Optimized structures obtained with less demanding computational procedures were compared to the MP2/haTZ ones using both MP2/haTZ single point energies and the root-mean-square (RMS) deviations of unweighted Cartesian coordinates. Based on these criteria, B3LYP/6-31+G(d,2p) substantially outperforms both HF/haTZ and MP2/6-31Gz.ast. B3LYP/6-31+G(d,2p) structures never …
Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann
Lattice Dynamics In The Fesb₃ Skutterudite, Anne Möchel, Ilya Sergueev, Ngoc Thanh Nguyen, Gary J. Long, Fernande Grandjean, D. C. Johnson, Raphäel P. Hermann
Chemistry Faculty Research & Creative Works
Thin films of FeSb3 were characterized by electronic transport, magnetometry, x-ray diffraction, 57Fe and 121Sb nuclear inelastic scattering, and 57Fe Mössbauer spectroscopy. Resistivity and magnetometry measurements reveal semiconducting behavior with a 16.3(4) meV band gap and an effective paramagnetic moment of 0.57(6) B, respectively. A systematic comparison of the lattice dynamics with CoSb3 and EuFe 4Sb12 reveals that the Fe4Sb12 framework is softer than the Co4Sb12 framework, and that the observed softening and the associated lowering of the lattice thermal conductivity in the RFe4Sb12 filled skutterudites …
A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak
A Large-Scale Synthesis And Characterization Of Quaternary Cuinₓga₁₋ₓs₂ Chalcopyrite Nanoparticles Via Microwave Batch Reactions, Chivin Sun, Richard D. Westover, Gary J. Long, Cyril Bajracharya, Jerry D. Harris, Alexander Punnoose, René G. Rodriguez, Joshua J. Pak
Chemistry Faculty Research & Creative Works
Various quaternary CuInxGa1-xS2 (0≤x≤1) chalcopyrite nanoparticles have been prepared from molecular single-source precursors via microwave decomposition. We were able to control the nanoparticle size, phase, stoichiometry, and solubility. Depending on the choice of surface modifiers used, we were able to tune the solubility of the resulting nanoparticles. This method has been used to generate up to 5g of nanoparticles and up to 150g from multiple batch reactions with excellent reproducibility. Data from UV-Vis, photoluminescence, X-ray diffraction, TEM, DSC/TGA-MS, and ICP-OES analyses have shown high reproducibility in nanoparticle size, composition, and bandgap.
Development Of A 3-Body:Many-Body Integrated Fragmentation Method For Weakly Bound Clusters And Application To Water Clusters (H2o) N=3-10, 16, 17, Desiree M. Bates, Joshua R. Smith, Tomasz Janowski, Gregory S. Tschumper
Development Of A 3-Body:Many-Body Integrated Fragmentation Method For Weakly Bound Clusters And Application To Water Clusters (H2o) N=3-10, 16, 17, Desiree M. Bates, Joshua R. Smith, Tomasz Janowski, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
A 3-body:many-body integrated quantum mechanical (QM) fragmentation method for non-covalent clusters is introduced within the ONIOM formalism. The technique captures all 1-, 2-, and 3-body interactions with a high-level electronic structure method, while a less demanding low-level method is employed to recover 4-body and higher-order interactions. When systematically applied to 40 low-lying (H2O)n isomers ranging in size from n = 3 to 10, the CCSD(T):MP2 3-body:many-body fragmentation scheme deviates from the full CCSD(T) interaction energy by no more than 0.07 kcal mol-1 (or < 0.01 kcal mol-1 per water). The errors for this QM:QM method increase only slightly for various low-lying isomers of (H2O)16 and (H2O)17 (always within 0.13 kcal mol-1 …
Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier
Bis[2-(1h-Imidazol-2-Yl-Κn³)-1h-Imidazol-3-Ium]Silver(I) Trinitrate, Shelonda R. Finch, J. P. Harper, Amitava Choudhury, Ekkehard Sinn, Harvest L. Collier
Chemistry Faculty Research & Creative Works
The synthesis of the title salt, [Ag(C 6H 7N 4) 2](NO 3) 3, was carried out employing a 1:2 molar ratio of 2,2'-biimidazole and silver nitrate respectively. The cation has crystallographically-imposed C2 symmetry with the metal atom in an almost linear coordination environment [N - Ag - N = 177.01 (17)°]. The crystal structure displays N - H⋯O and C - H⋯O hydrogen-bonding interactions.
Vibrational Spectroscopy Of N-Methyliminodiacetic Acid (Mida)-Protected Boronate Ester: Examination Of The B-N Dative Bond, Dana N. Reinemann, Ashley M. Wright, Jonathan D. Wolfe, Gregory S. Tschumper, Nathan I. Hammer
Vibrational Spectroscopy Of N-Methyliminodiacetic Acid (Mida)-Protected Boronate Ester: Examination Of The B-N Dative Bond, Dana N. Reinemann, Ashley M. Wright, Jonathan D. Wolfe, Gregory S. Tschumper, Nathan I. Hammer
Chemistry Faculty Research & Creative Works
N-Methyliminodiacetic acid (MIDA)-protected boronate esters are a new class of reagents that offer great promise in iterative Suzuki-Miyaura cross-coupling reactions. Compared to earlier reagents, MIDA esters are easily handled and are benchtop stable under air indefinitely. The success of this new species is tied to its unique molecular architecture. Compared to the simpler B-N containing molecules ammonia borane and trimethylamine borane, MIDA esters are much larger, and the sp3 hybridized boron atom is secured by two five membered rings, making this molecular class stable for spectroscopic study. Here, we present infrared, Raman, and surface enhanced Raman (SERS) spectra of methylboronic …
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Slow Magnetic Relaxation And Electron Delocalization In An S = 9/2 Iron(Ii/Iii) Complex With Two Crystallographically Inequivalent Iron Sites, Susanta Hazra, Sujit Sasmal, Michel Fleck, Fernande Grandjean, Moulay T. Sougrati, Meenakshi Ghosh, T. David Harris, Pierre Bonville, Gary J. Long, Sasankasekhar Mohanta
Chemistry Faculty Research & Creative Works
The magnetic, electronic, and Mössbauer spectral properties of Fe 2L(µ-OAc)2ClO4, 1, where L is the dianion of the tetraimino-diphenolate macrocyclic ligand, H2L, indicate that 1 is a class III mixed valence iron(II/III) complex with an electron that is fully delocalized between two crystallographically inequivalent iron sites to yield a [Fe2]V cationic configuration with a St 9/2 ground state. Fits of the dc magnetic susceptibility between 2 and 300K and of the isofield variable-temperature magnetization of 1 yield an isotropic magnetic exchange parameter, J, of -32(2) cm-1 for an …
Spectroscopic And Computational Insight Into Weak Noncovalent Interactions In Crystalline Pyrimidine, Ashley M. Wright, Lynn V. Joe, Austin A. Howard, Gregory S. Tschumper, Nathan I. Hammer
Spectroscopic And Computational Insight Into Weak Noncovalent Interactions In Crystalline Pyrimidine, Ashley M. Wright, Lynn V. Joe, Austin A. Howard, Gregory S. Tschumper, Nathan I. Hammer
Chemistry Faculty Research & Creative Works
Effects of weak C-H⋯N interactions on the vibrational spectrum of crystalline pyrimidine are studied using Raman spectroscopy and electronic structure computations. When pyrimidine transitions from the liquid to solid state, peaks in the Raman spectrum exhibit non-uniform shifts. Calculations performed on a cluster of nine pyrimidine molecules (one pyrimidine molecule embedded in a field of its eight nearest neighbors in the crystalline geometry) predict that modes involving the movement of hydrogen atoms are associated with the observed shifts. Assignments of fundamentals and combination bands in both the liquid and solid states are also revised in the complicated C-H stretching region. …
Enhanced Photorefractivity In A Polymeric Composite Photosensitized With Carbon Nanotubes Grafted To A Photoconductive Polymer, Naveen Kumar Lingam, Sonali Kalghatgi, Jeffrey G. Winiarz
Enhanced Photorefractivity In A Polymeric Composite Photosensitized With Carbon Nanotubes Grafted To A Photoconductive Polymer, Naveen Kumar Lingam, Sonali Kalghatgi, Jeffrey G. Winiarz
Chemistry Faculty Research & Creative Works
We report on the photosensitization of photorefractive (PR) polymeric composites through the inclusion of multiwalled and singlewalled carbon nanotubes (CNTs), respectively, having poly(N -vinyl carbazole) (PVK) grafted to their surfaces. The PR nature of the holographic gratings was confirmed via the asymmetric exchange of energy in a two-beam-coupling (TBC) geometry, yielding TBC gain coefficients approaching 80 cm-1. In addition, in degenerate-four-wave- mixing experiments the prepared composites exhibited diffraction efficiencies as high as 60% and overmodulation voltages as low as ∼40 V/μm. These notable figures of merit indicate that the grafting of the PVK polymer to the various CNTs …
Aspergillus Fumigatus Sida Is A Highly Specific Ornithine Hydroxylase With Bound Flavin Cofactor, Samuel W. Chocklett, Pablo Sobrado
Aspergillus Fumigatus Sida Is A Highly Specific Ornithine Hydroxylase With Bound Flavin Cofactor, Samuel W. Chocklett, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N5-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed and purified as a soluble tetramer and is the first member of this class of flavin monooxygenases to be isolated with a bound flavin cofactor. The enzyme showed typical saturation kinetics with respect to l-ornithine while substrate inhibition was observed at high concentrations of NADPH and NADH. Increasing amounts of hydrogen peroxide were measured …
Hydrogen Storage And Carbon Dioxide Capture In An Iron-Based Sodalite-Type Metal-Organic Framework (Fe-Btt) Discovered Via High-Throughput Methods, Kenji Sumida, Satoshi Horike, Steven S. Kaye, Zoey R. Herm, Wendy L. Queen, Craig M. Brown, Fernande Grandjean, Gary J. Long, Anne M. Dailly, Jeffrey R. Long
Hydrogen Storage And Carbon Dioxide Capture In An Iron-Based Sodalite-Type Metal-Organic Framework (Fe-Btt) Discovered Via High-Throughput Methods, Kenji Sumida, Satoshi Horike, Steven S. Kaye, Zoey R. Herm, Wendy L. Queen, Craig M. Brown, Fernande Grandjean, Gary J. Long, Anne M. Dailly, Jeffrey R. Long
Chemistry Faculty Research & Creative Works
Using high-throughput instrumentation to screen conditions, the reaction between FeCl2 and H3BTT·2HCl (BTT3- = 1,3,5-benzenetristetrazolate) in a mixture of DMF and DMSO was found to afford Fe3[(Fe4Cl)3(BTT)8] 2·22DMF·32DMSO·11H2O. This compound adopts a porous three-dimensional framework structure consisting of square [Fe4Cl]7+ units linked via triangular BTT3- bridging ligands to give an anionic 3,8-net. Mössbauer spectroscopy carried out on a DMF-solvated version of the material indicated the framework to contain high-spin Fe2+ with a distribution of local environments and confirmed the presence …
Effects Of Hydrogen Bonding On Vibrational Normal Modes Of Pyrimidine, Austin A. Howard, Gregory S. Tschumper, Nathan I. Hammer
Effects Of Hydrogen Bonding On Vibrational Normal Modes Of Pyrimidine, Austin A. Howard, Gregory S. Tschumper, Nathan I. Hammer
Chemistry Faculty Research & Creative Works
The effects of weak intermolecular interactions on 10 vibrational normal modes of pyrimidine are investigated by Raman spectroscopy and electronic structure computations. Hydrogen-bonded networks of water induce a shift to higher energy in certain normal modes of pyrimidine with increasing water concentration, while other modes are relatively unaffected. Pyrimidine molecules also exhibit weak C-H⋯N interactions and shifted normal modes upon crystallization. The selective nature of the shifting of normal modes to higher energy allows for definitive assignments of the nearly degenerate ν8a and ν8b modes with polarized Raman spectroscopy. Natural bond orbital (NBO) analyses indicate that when water molecules donate …
Analysis Of Globule Types In Malignant Melanoma, Jin Xu, Kapil Kumar Gupta, William V. Stoecker, Yamini Krishnamurthy, Harold S. Rabinovitz, Austin Bangert, David A. Calcara, Margaret C. Oliviero, Joseph M. Malters, Rhett J. Drugge, R. Joe Stanley, Randy Hays Moss, Mehmed Emre Celebi
Analysis Of Globule Types In Malignant Melanoma, Jin Xu, Kapil Kumar Gupta, William V. Stoecker, Yamini Krishnamurthy, Harold S. Rabinovitz, Austin Bangert, David A. Calcara, Margaret C. Oliviero, Joseph M. Malters, Rhett J. Drugge, R. Joe Stanley, Randy Hays Moss, Mehmed Emre Celebi
Chemistry Faculty Research & Creative Works
Objective: To identify and analyze subtypes of globules based on size, shape, network connectedness, pigmentation, and distribution to determine which globule types and globule distributions are most frequently associated with a diagnosis of malignant melanoma. Design: Retrospective case series of dermoscopy images with globules. Setting: Private dermatology practices. Participants: Patients in dermatology practices. Intervention: Observation only. Main Outcome Measure: Association of globule types with malignant melanoma. Results: The presence of large globules (odds ratio [OR], 5.25) and globules varying in size (4.72) or shape (5.37) had the highest ORs for malignant melanoma among all globule types and combinations studied. Classical …
Combined Mössbauer Spectral And Density Functional Theory Determination Of The Magnetic Easy-Axis In Two High-Spin Iron(Ii) 2-Pyrazinecarboxylate Complexes, Gary J. Long, Stefania Tanase, Françoise Remacle, Ganga Periyasamy, Fernande Grandjean
Combined Mössbauer Spectral And Density Functional Theory Determination Of The Magnetic Easy-Axis In Two High-Spin Iron(Ii) 2-Pyrazinecarboxylate Complexes, Gary J. Long, Stefania Tanase, Françoise Remacle, Ganga Periyasamy, Fernande Grandjean
Chemistry Faculty Research & Creative Works
A combination of density functional theory (DFT) calculations and Mössbauer spectroscopy has been used to determine that the magnetic easy-axis is coincident with its crystallography c-axis in [Fe(pca) 2(py)2] · py, where pac is the 2- pyrazinecarboxylate ligand. This easy-axis bisects the approximately axial O-Fe-O coordination axes of molecules adjacent to each other along the c-axis. in {[Fe(pca)2(H2O)]-H2O) n the easy magnetic axis is not coincident with any of its crystallographic axes nor with the Fe-O(water) coordination axis, but is coincident with one of the Fe ... Fe axes in the crystal structure. the DFT calculations, …
Rapid Responders To Frovatriptan In Acute Migraine Treatment: Results From A Long-Term, Open-Label Study, Egilius L.H. Spierings, Egilius L.H. Spierings, Charlotte Keywood, Jeffrey Baggish, Harvey J. Blumenthal, Roger K. Cady, David H. Cook, Seymour Diamond, Keith R. Edwards, David L. Friedgood, Ronald C. Gove, Daniel B. Hier, Robert G. Kaniecki, David Kudrow
Rapid Responders To Frovatriptan In Acute Migraine Treatment: Results From A Long-Term, Open-Label Study, Egilius L.H. Spierings, Egilius L.H. Spierings, Charlotte Keywood, Jeffrey Baggish, Harvey J. Blumenthal, Roger K. Cady, David H. Cook, Seymour Diamond, Keith R. Edwards, David L. Friedgood, Ronald C. Gove, Daniel B. Hier, Robert G. Kaniecki, David Kudrow
Chemistry Faculty Research & Creative Works
Background. the Chronic Nature of Migraine and the Reliance on Acute Treatment Constitute the Basis of the Present Long-Term, Open-Label Study. Objectives. First, Assessment of the Tolerability and Safety of Frovatriptan, 2.5-7.5 Mg Taken Orally over 24 Hours, for the Acute Treatment of Migraine, Repeatedly over a 12-Month Period. Second, Assessment of the Efficacy and Tolerability of a Second, Double-Blind Dose of 2.5-Mg Frovatriptan, Compared with Placebo, for Nonresponse at 2 Hours after Treatment of Moderate or Severe Headache with 2.5-Mg Frovatriptan. Results. with Regard to the First Attack Treated, 173 (36%) of the 486 Subjects in the Study Did …
A Structural, Magnetic, And Mössbauer Spectral Study Of The Tbco₄₋ₓfeₓb Compounds With X=0, 1, And 2, Herv´ Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
A Structural, Magnetic, And Mössbauer Spectral Study Of The Tbco₄₋ₓfeₓb Compounds With X=0, 1, And 2, Herv´ Mayot, Olivier Isnard, Fernande Grandjean, Gary J. Long
Chemistry Faculty Research & Creative Works
The TbCo4-x Fex B compounds with x=0, 1, and 2 have been investigated by x-ray and neutron diffraction, magnetic measurements, and iron-57 Mössbauer spectroscopy. The substitution of cobalt by iron induces both an anisotropic increase in the unit-cell volume and a large increase of approximately 250 K in the Curie temperature; the 4.2 K magnetization decreases continuously with increasing iron content. The powder neutron diffraction patterns and the Mössbauer spectra of the TbCo4-x Fex B compounds reveal a strong preferential substitution of iron for cobalt on the 2c site, small transition metal magnetic moments of approximately …
Developmental Expression Of Xenopus Myosin 1d And Identification Of A Myo1d Tail Homology That Overlaps Th1, Janine M. Leblanc-Straceski, Anna Sokac, William Bement, Pablo Sobrado, Laura Lemoine
Developmental Expression Of Xenopus Myosin 1d And Identification Of A Myo1d Tail Homology That Overlaps Th1, Janine M. Leblanc-Straceski, Anna Sokac, William Bement, Pablo Sobrado, Laura Lemoine
Chemistry Faculty Research & Creative Works
Xenopus laevis myosin 1d (XlMyo1d) is a member of the myosin I class, subclass 4. Members of this class are single headed, bind calmodulin light chains and have lipid binding domains in their tails. The rat myo1d homologue has been implicated in endosome vesicle recycling in epithelial cells. Mutations in the Drosophila myosin 1d homologue cause situs inversus in the abdomen. The XlMyo1d cDNA has been cloned and the derived amino acid sequence is 80% identical to the rat and human homologues. Sequence comparison revealed a novel isoform-specific tail homology embedded in the Tail Homology 1 (TH1) domain characteristic of …
Ccsd(T) Complete Basis Set Limit Relative Energies For Low-Lying Water Hexamer Structures, Desiree M. Bates, Gregory S. Tschumper
Ccsd(T) Complete Basis Set Limit Relative Energies For Low-Lying Water Hexamer Structures, Desiree M. Bates, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
MP2 and CCSD(T) complete basis set (CBS) limit relative electronic energies (ΔE e) have been determined for eight low-lying structures of the water hexamer by combining explicitly correlated MP2-R12 computations with higher-order correlation corrections from CCSD(T) calculations. Higher-order correlation effects are quite substantial and increase ΔE e by at least +0.19 kcalmol-1 and as much as +0.59 kcalmol-1. The effects from zero-point vibrational energy (ZPVE) have been assessed from unsealed harmonic vibrational frequencies computed at the MP2 level with a correlation consistent triple-̌ basis set (cc-pVTZ for H and aug-cc-pVTZ for O). ZPVE effects are even more …