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Articles 241 - 270 of 939
Full-Text Articles in Chemistry
Continuous Measurement Of Reactive Oxygen Species Inside And Outside Of A Residential House During Summer, Azin Eftekhari, Claire F. Fortenberry, Brent J. Williams, Michael J. Walker, Audrey Dang, Annalise Pfaff, Nuran Ercal, Glenn C. Morrison
Continuous Measurement Of Reactive Oxygen Species Inside And Outside Of A Residential House During Summer, Azin Eftekhari, Claire F. Fortenberry, Brent J. Williams, Michael J. Walker, Audrey Dang, Annalise Pfaff, Nuran Ercal, Glenn C. Morrison
Chemistry Faculty Research & Creative Works
Reactive oxygen species (ROS) are an important contributor to adverse health effects associated with ambient air pollution. Despite infiltration of ROS from outdoors, and possible indoor sources (eg, combustion), there are limited data available on indoor ROS. In this study, part of the second phase of Air Composition and Reactivity from Outdoor aNd Indoor Mixing campaign (ACRONIM-2), we constructed and deployed an online, continuous, system to measure extracellular gas- and particle-phase ROS during summer in an unoccupied residence in St. Louis, MO, USA. Over a period of one week, we observed that the non-denuded outdoor ROS (representing particle-phase ROS and …
Copper Selenide As Multifunctional Non-Enzymatic Glucose And Dopamine Sensor, Harish Singh, Jillian Bernabe, Justin Chern, Manashi Nath
Copper Selenide As Multifunctional Non-Enzymatic Glucose And Dopamine Sensor, Harish Singh, Jillian Bernabe, Justin Chern, Manashi Nath
Chemistry Faculty Research & Creative Works
Cu2Se, synthesized through one-pot hydrothermal synthesis, was identified as highly efficient bifunctional sensor for co-detection of glucose and dopamine with high selectivity. As-synthesized copper selenide could electro-oxidize glucose and dopamine at different applied potentials. Glucose oxidation was observed at 0.35 V while dopamine oxidized at 0.2 V. This copper selenide-based non-enzymatic sensor showed high sensitivity for both glucose (15.341 mA mM-1 cm-2) and dopamine (12.43 μA μM-1 cm-2) with low limit of detection (0.26 μM and 84 nM). Such high sensitivity and low LOD makes this sensor attractive for possible detection of …
Temperature-Dependent Rotationally Inelastic Collisions Of Ohˉ And He, Eric S. Endres, Steve Ndengué, Olga Lakhmanskaya, Seunghyun Lee, Francesco A. Gianturco, Richard Dawes, Roland Wester
Temperature-Dependent Rotationally Inelastic Collisions Of Ohˉ And He, Eric S. Endres, Steve Ndengué, Olga Lakhmanskaya, Seunghyun Lee, Francesco A. Gianturco, Richard Dawes, Roland Wester
Chemistry Faculty Research & Creative Works
We have studied the fundamental rotational relaxation and excitation collision of OHˉJ = 0 ↔ 1 with helium at different collision energies. Using state-selected photodetachment in a cryogenic ion trap, the collisional excitation of the first excited rotational state of OHˉ has been investigated and absolute inelastic collision rate coefficients have been extracted for collision temperatures between 20 and 35 K. The rates are compared with accurate quantum scattering calculations for three different potential-energy surfaces. Good agreement is found within the experimental accuracy, but the experimental trend of increasing collision rates with temperature is only in part reflected in the …
Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski
Enantioselective Nickel-Catalyzed Alkyne-Azide Cycloaddition By Dynamic Kinetic Resolution, En Chih Liu, Joseph J. Topczewski
Chemistry Faculty Research & Creative Works
The triazole heterocycle has been widely adopted as an isostere for the amide bond. Many native amides are α-chiral, being derived from amino acids. This makes α-N-chiral triazoles attractive building blocks. This report describes the first enantioselective triazole synthesis that proceeds via nickel-catalyzed alkyne-azide cycloaddition (NiAAC). This dynamic kinetic resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide. The 1,4,5-trisubstituted triazole products, derived from internal alkynes, are complementary to those commonly obtained by the related CuAAC reaction. Initial mechanistic experiments indicate that the NiAAC reaction proceeds through a monometallic Ni complex, which is distinct from the CuAAC …
Metal Foils With Ordered Crystal Structure And Method For Producing Metal Foils, Jay A. Switzer
Metal Foils With Ordered Crystal Structure And Method For Producing Metal Foils, Jay A. Switzer
Chemistry Faculty Research & Creative Works
A method for producing a metal foil comprising depositing metal onto an oxidizable substrate to form a metal film on the substrate; oxidizing the substrate at an interface between the metal film and the substrate; and removing the metal film from the substrate to yield a metal foil. A method for forming a thin metal film comprising pre-polarizing a single-crystal Si substrate by application of a potential which is negative of a potential at which Si oxidizes, which pre-polarization occurs in the presence of metal ions to form metal growth nucleation sites on the substrate, followed by application of a …
Achieving Superlubricity With 2d Transition Metal Carbides (Mxenes) And Mxene/Graphene Coatings, S. Huang, K. C. Mutyala, A. V. Sumant, Vadym Mochalin
Achieving Superlubricity With 2d Transition Metal Carbides (Mxenes) And Mxene/Graphene Coatings, S. Huang, K. C. Mutyala, A. V. Sumant, Vadym Mochalin
Chemistry Faculty Research & Creative Works
Two-dimensional (2D) materials have demonstrated unique friction and antiwear properties unmatched by their bulk (3D) counterparts. A relatively new, large and quickly growing family of two-dimensional early transition metal carbides and nitrides (MXenes) present a great potential in different applications. There is a growing interest in understanding the mechanical and tribological properties of MXenes, however, no report of MXene superlubricity in a solid lubrication process at the macroscale has been presented. Here we investigate the tribological properties of two-dimensional titanium carbide (Ti3C2) MXene deposited on SiO2-coated silicon (Si) substrates subjected to wear by sliding …
High-Throughput Screen For Inhibitors Of The Type Iv Pilus Assembly Atpase Pilb, Keane J. Dye, Nancy J. Vogelaar, Pablo Sobrado, Zhaomin Yang
High-Throughput Screen For Inhibitors Of The Type Iv Pilus Assembly Atpase Pilb, Keane J. Dye, Nancy J. Vogelaar, Pablo Sobrado, Zhaomin Yang
Chemistry Faculty Research & Creative Works
The bacterial type IV pilus (T4P) is a prominent virulence factor in many significant human pathogens, some of which have become increasingly antibiotic resistant. Antivirulence chemotherapeutics are considered a promising alternative to antibiotics because they target the disease process instead of bacterial viability. However, a roadblock to the discovery of anti-T4P compounds is the lack of a high throughput screen (HTS) that can be implemented relatively easily and economically. Here, we describe the first HTS for the identification of inhibitors specifically against the T4P assembly ATPase PilB in vitro. Chloracidobacterium thermophilum PilB (CtPilB) had been demonstrated to have robust ATPase …
Disaggregation Of Nanodiamond Particles, Vadym Mochalin, Atsushi Kume, Yoshihiro Inamoto, Masumi Hashimoto
Disaggregation Of Nanodiamond Particles, Vadym Mochalin, Atsushi Kume, Yoshihiro Inamoto, Masumi Hashimoto
Chemistry Faculty Research & Creative Works
Methods for disaggregating nanodiamond clusters, for example, by using sonication to break apart nanodiamond aggregates in an aqueous slurry having an alkaline pH. Compositions, such as aqueous nanodiamond dispersions and dry particulate compositions can be produced using these methods.
A Molecular Tetrahedral Cobalt-Seleno-Based Complex As An Efficient Electrocatalyst For Water Splitting, Ibrahim Munkaila Abdullahi, Jahangir Masud, Polydoros Chrisovalantis Ioannou, Eleftherios Ferentinos, Panayotis Kyritsis, Manashi Nath
A Molecular Tetrahedral Cobalt-Seleno-Based Complex As An Efficient Electrocatalyst For Water Splitting, Ibrahim Munkaila Abdullahi, Jahangir Masud, Polydoros Chrisovalantis Ioannou, Eleftherios Ferentinos, Panayotis Kyritsis, Manashi Nath
Chemistry Faculty Research & Creative Works
The cobalt-seleno-based coordination complex, [Co{(SePiPr2)2N}2], is reported with respect to its catalytic activity in oxygen evolution and hydrogen evolution reactions (OER and HER, respectively) in alkaline solutions. An overpotential of 320 and 630 mV was required to achieve 10 mA cm-2 for OER and HER, respectively. The overpotential for OER of this CoSe4-containing complex is one of the lowest that has been observed until now for molecular cobalt(II) systems, under the reported conditions. In addition, this cobalt-seleno-based complex exhibits a high mass activity (14.15 A g-1) and …
Interplay Between Oxo And Fluoro In Vanadium Oxyfluorides For Centrosymmetric And Non-Centrosymmetric Structure Formation, Prashanth Sandineni, Amitava Choudhury, Hooman Yaghoobnejad Asl, Weiguo Zhang, P. Shiv Halasyamani, Kartik Ghosh
Interplay Between Oxo And Fluoro In Vanadium Oxyfluorides For Centrosymmetric And Non-Centrosymmetric Structure Formation, Prashanth Sandineni, Amitava Choudhury, Hooman Yaghoobnejad Asl, Weiguo Zhang, P. Shiv Halasyamani, Kartik Ghosh
Chemistry Faculty Research & Creative Works
Herein, we report the syntheses of two lithium-vanadium oxide-fluoride compounds crystallized from the same reaction mixture through a time variation experiment. A low temperature hydrothermal route employing a viscous paste of V2O5, oxalic acid, LiF, and HF allowed the crystallization of one metastable phase initially, Li2VO0.55 (H2O)0.45F5·2H2O (I), which on prolonged heating transforms to a chemically similar yet structurally different phase, Li3VOF5 (II). Compound I crystallizes in centrosymmetric space group, I2/a with a = 6.052(3), b = 7.928(4), …
Physicochemical Properties And Formulation Development Of A Novel Compound Inhibiting Staphylococcus Aureus Biofilm Formation, Nan Wang, Feng Qi, Haqing Yu, Bryan D. Yestrepsky, Scott D. Larsen, Honglan Shi, Juan Ji, David W. Anderson, Hao Li, Hongmin Sun
Physicochemical Properties And Formulation Development Of A Novel Compound Inhibiting Staphylococcus Aureus Biofilm Formation, Nan Wang, Feng Qi, Haqing Yu, Bryan D. Yestrepsky, Scott D. Larsen, Honglan Shi, Juan Ji, David W. Anderson, Hao Li, Hongmin Sun
Chemistry Faculty Research & Creative Works
The emergence of antibiotic resistance over the past several decades has given urgency to new antibacterial strategies that apply less selective pressure. A new class of anti-virulence compounds were developed that are active against methicillin-resistant Staphylococcus aureus (MRSA), by inhibiting bacterial virulence without hindering their growth to reduce the selective pressure for resistance development. One of the compounds CCG-211790 has demonstrated potent anti-biofilm activity against MRSA. This new class of anti-virulence compounds inhibited the gene expression of virulence factors involved in biofilm formation and disrupted the biofilm structures. In this study, the physicochemical properties of CCG- 211790, including morphology, solubility …
Collisional Excitation Of Interstellar Pn By H₂: New Interaction Potential And Scattering Calculations, Benjamin Desrousseaux, Ernesto Quintas-Sánchez, Richard Dawes, Sarantos Marinakis, François Lique
Collisional Excitation Of Interstellar Pn By H₂: New Interaction Potential And Scattering Calculations, Benjamin Desrousseaux, Ernesto Quintas-Sánchez, Richard Dawes, Sarantos Marinakis, François Lique
Chemistry Faculty Research & Creative Works
Rotational excitation of interstellar PN molecules induced by collisions with H2 is investigated. We present the first ab initio four-dimensional potential energy surface (PES) for the PN-H2 van der Waals system. The PES was obtained using an explicitly correlated coupled cluster approach with single, double, and perturbative triple excitations [CCSD(T)-F12b]. The method of interpolating moving least squares was used to construct an analytical PES from these data. The equilibrium structure of the complex was found to be linear, with H2 aligned at the N end of the PN molecule, at an intermolecular separation of 4.2 Å. The …
Biochemical Characterization Of The Two-Component Flavin-Dependent Monooxygenase Involved In Valanimycin Biosynthesis, Hao Li, Benedicta Forson, Meital Eckshtain-Levi, Hannah Valentino, Julia S. Martín Del Campo, John J. Tanner, Pablo Sobrado
Biochemical Characterization Of The Two-Component Flavin-Dependent Monooxygenase Involved In Valanimycin Biosynthesis, Hao Li, Benedicta Forson, Meital Eckshtain-Levi, Hannah Valentino, Julia S. Martín Del Campo, John J. Tanner, Pablo Sobrado
Chemistry Faculty Research & Creative Works
The flavin reductase (FRED) and isobutyl amine N-hydroxylase (IBAH) from Streptomyces viridifaciens constitute a two-component, flavin-dependent monooxygenase system that catalyzes the first step in valanimycin biosynthesis. FRED is an oxidoreductase that provides the reduced flavin to IBAH, which then catalyzes the hydroxylation of isobutyl amine (IBA) to isobutyl hydroxylamine (IBHA). In this work, we used several complementary methods to investigate FAD binding, steady-state and rapid reaction kinetics, and enzyme-enzyme interactions in the FRED: IBAH system. The affinity of FRED for FADox is higher than its affinity for FADred, consistent with its function as a flavin reductase. Conversely, IBAH binds FADred …
Preparation Of Green Biosorbent Using Rice Hull To Preconcentrate, Remove And Recover Heavy Metal And Other Metal Elements From Water, Yongbo Dan, Lei Xu, Zhimin Qiang, Huiyu Dong, Honglan Shi
Preparation Of Green Biosorbent Using Rice Hull To Preconcentrate, Remove And Recover Heavy Metal And Other Metal Elements From Water, Yongbo Dan, Lei Xu, Zhimin Qiang, Huiyu Dong, Honglan Shi
Chemistry Faculty Research & Creative Works
Sodium hydroxide treated rice hulls were investigated to preconcentrate, remove, and recover metal ions including Be2+, Al3+, Cr3+, CO2+, Ni2+, Cu2+, Zn2+, Sr2+, Ag+, Cd2+, Ba2+, and Pb2+ in both batch mode and column mode. Sodium hydroxide treatment significantly improved the removal efficiency for all metal ions of interest compared to the untreated rice hull. The removal kinetics were extremely fast for Co, Ni, Cu, Zn, Sr, Cd, and Ba, which made the treated rice hull a …
Schizophrenia Classification Using Resting State Eeg Functional Connectivity: Source Level Outperforms Sensor Level, Sima Azizi, Daniel B. Hier, Donald C. Wunsch
Schizophrenia Classification Using Resting State Eeg Functional Connectivity: Source Level Outperforms Sensor Level, Sima Azizi, Daniel B. Hier, Donald C. Wunsch
Chemistry Faculty Research & Creative Works
Disrupted Functional and Structural Connectivity Measures Have Been Used to Distinguish Schizophrenia Patients from Healthy Controls. Classification Methods based on Functional Connectivity Derived from EEG Signals Are Limited by the Volume Conduction Problem. Recorded Time Series at Scalp Electrodes Capture a Mixture of Common Sources Signals, Resulting in Spurious Connections. We Have Transformed Sensor Level Resting State EEG Times Series to Source Level EEG Signals Utilizing a Source Reconstruction Method. Functional Connectivity Networks Were Calculated by Computing Phase Lag Values between Brain Regions at Both the Sensor and Source Level. Brain Complex Network Analysis Was Used to Extract Features and …
Subsumption Reduces Dataset Dimensionality Without Decreasing Performance Of A Machine Learning Classifier, Donald C. Wunsch, Daniel B. Hier
Subsumption Reduces Dataset Dimensionality Without Decreasing Performance Of A Machine Learning Classifier, Donald C. Wunsch, Daniel B. Hier
Chemistry Faculty Research & Creative Works
When Features in a High Dimension Dataset Are Organized Hierarchically, There is an Inherent Opportunity to Reduce Dimensionality. Since More Specific Concepts Are Subsumed by More General Concepts, Subsumption Can Be Applied Successively to Reduce Dimensionality. We Tested Whether Sub-Sumption Could Reduce the Dimensionality of a Disease Dataset Without Impairing Classification Accuracy. We Started with a Dataset that Had 168 Neurological Patients, 14 Diagnoses, and 293 Unique Features. We Applied Subsumption Repeatedly to Create Eight Successively Smaller Datasets, Ranging from 293 Dimensions in the Largest Dataset to 11 Dimensions in the Smallest Dataset. We Tested a MLP Classifier on All …
Nanostructured Copper Selenide As An Ultrasensitive And Selective Non-Enzymatic Glucose Sensor, Siddesh Umapathi, Harish Singh, Jahangir Masud, Manashi Nath
Nanostructured Copper Selenide As An Ultrasensitive And Selective Non-Enzymatic Glucose Sensor, Siddesh Umapathi, Harish Singh, Jahangir Masud, Manashi Nath
Chemistry Faculty Research & Creative Works
CuSe nanostructures exhibit high-efficiency for glucose detection with high sensitivity (19.419 mA mM-1 cm-2) and selectivity at a low applied potential of +0.15 V vs. Ag|AgCl, a low detection limit of 0.196 μM and a linear range of glucose detection from 100 nm. to 40 μM. This journal is
A Deep Learning Model To Predict Traumatic Brain Injury Severity And Outcome From Mr Images, Dacosta Yeboah, Hung Nguyen, Daniel B. Hier, Gayla R. Olbricht, Tayo Obafemi-Ajayi
A Deep Learning Model To Predict Traumatic Brain Injury Severity And Outcome From Mr Images, Dacosta Yeboah, Hung Nguyen, Daniel B. Hier, Gayla R. Olbricht, Tayo Obafemi-Ajayi
Chemistry Faculty Research & Creative Works
For Many Neurological Disorders, Including Traumatic Brain Injury (TBI), Neuroimaging Information Plays a Crucial Role Determining Diagnosis and Prognosis. TBI is a Heterogeneous Disorder that Can Result in Lasting Physical, Emotional and Cognitive Impairments. Magnetic Resonance Imaging (MRI) is a Non-Invasive Technique that Uses Radio Waves to Reveal Fine Details of Brain Anatomy and Pathology. Although MRIs Are Interpreted by Radiologists, Advances Are Being Made in the Use of Deep Learning for MRI Interpretation. This Work Evaluates a Deep Learning Model based on a Residual Learning Convolutional Neural Network that Predicts TBI Severity from MR Images. the Model Achieved a …
Cf⁺ Excitation In The Interstellar Medium, Benjamin Desrousseaux, François Lique, Javier R. Goicoechea, Ernesto Quintas-Sánchez, Richard Dawes
Cf⁺ Excitation In The Interstellar Medium, Benjamin Desrousseaux, François Lique, Javier R. Goicoechea, Ernesto Quintas-Sánchez, Richard Dawes
Chemistry Faculty Research & Creative Works
The detection of CF+ in interstellar clouds potentially allows astronomers to infer the elemental fluorine abundance and the ionization fraction in ultraviolet-illuminated molecular gas. Because local thermodynamic equilibrium (LTE) conditions are hardly fulfilled in the interstellar medium (ISM), the accurate determination of the CF+ abundance requires one to model its non-LTE excitation via both radiative and collisional processes. Here, we report quantum calculations of rate coefficients for the rotational excitation of CF+ in collisions with para- and ortho-H2 (for temperatures up to 150 K). As an application, we present non-LTE excitation models that reveal population inversion …
Structural Determinants Of Flavin Dynamics In A Class B Monooxygenase, Ashley C. Campbell, Reeder Robinson, Didier Mena-Aguilar, Pablo Sobrado, John J. Tanner
Structural Determinants Of Flavin Dynamics In A Class B Monooxygenase, Ashley C. Campbell, Reeder Robinson, Didier Mena-Aguilar, Pablo Sobrado, John J. Tanner
Chemistry Faculty Research & Creative Works
The ornithine hydroxylase known as SidA is a class B flavin monooxygenase that catalyzes the first step in the biosynthesis of hydroxamate-containing siderophores in Aspergillus fumigatus. Crystallographic studies of SidA revealed that the FAD undergoes dramatic conformational changes between out and in states during the catalytic cycle. We sought insight into the origins and purpose of flavin motion in class B monooxygenases by probing the function of Met101, a residue that contacts the pyrimidine ring of the in FAD. Steady-state kinetic measurements showed that the mutant variant M101A has a 25-fold lower turnover number. Pre-steady-state kinetic measurements, pH profiles, and …
Nerve Response To Superelastic Shape Memory Polyurethane Aerogels, Martina Rodriguez Sala, Omar Skalli, Nicholas Leventis, Firouzeh Sabri
Nerve Response To Superelastic Shape Memory Polyurethane Aerogels, Martina Rodriguez Sala, Omar Skalli, Nicholas Leventis, Firouzeh Sabri
Chemistry Faculty Research & Creative Works
We have previously shown the suitability of aerogels as scaffolds for neuronal cells. Here, we report on the use of super elastic shape memory polyurethane aerogels (SSMPA). SSMPA have a distinctly different stiffness than previously reported aerogels. The soft and deformable nature of SSMPA allowed for radial compression of the aerogel induced by a custom designed apparatus. This radial compression changed the pore diameter and surface roughness (Sa) of SSMPA, while maintaining similar stiffness. Two varieties of SSMPA were used, Mix-14 and Mix-18, with distinctly different pore diameters and Sa. Radial compression led to a decreased pore diameter, which, in …
Spincoating Epitaxial Films, Jay A. Switzer
Spincoating Epitaxial Films, Jay A. Switzer
Chemistry Faculty Research & Creative Works
A process for forming an epitaxial film comprising spinning a substrate having an ordered crystal structure ; heating the substrate during spinning to a temperature between 70° C. and 150° C .; dripping epitaxial film precursor solution onto the spinning substrate , where the precursor solution comprises inorganic film precursor material in a solvent ; and continuing the heating and spinning to remove the solvent and epitaxially grow the epitaxial film on the substrate .
Investigation Of The Evaporation Rate Of Water From Colloidal Unimolecular Polymer (Cup) Systems By Isothermal Tga, Peng Geng, Ashish Zore, Michael R. Van De Mark
Investigation Of The Evaporation Rate Of Water From Colloidal Unimolecular Polymer (Cup) Systems By Isothermal Tga, Peng Geng, Ashish Zore, Michael R. Van De Mark
Chemistry Faculty Research & Creative Works
Studies of the evaporation of aqueous nanoparticle solutions have been limited due to lack of homogeneity of the solution, difficulties in obtaining reproducible samples and stability of substrates, as well as the effect of other volatile components or contaminants such as surfactants. Colloidal unimolecular polymer (CUP) is a spheroidal nanoparticle with charged hydrophilic groups on the surface, and the particle size ranges from 3 to 9 nm. The large amount of surface water on the CUP surface provides the opportunity to evaluate the evaporation of surface water, which may contribute to the investigation the factors that affect the evaporation rate …
Corrigendum To “Biosynthesis Of Desferrioxamine Siderophores Initiated By Decarboxylases: A Functional Investigation Of Two Lysine/Ornithine-Decarboxylases From Gordonia Rubripertincta Cwb2 And Pimelobacter Simplex Vkm Ac-2033d” [Arch. Biochem. Biophys. 689 (2020) 108429] (Archives Of Biochemistry And Biophysics (2020) 689, (S0003986120304380), (10.1016/J.Abb.2020.108429)), Marika Hofmann, Julia S. Martin Del Campo, Pablo Sobrado, Dirk Tischler
Corrigendum To “Biosynthesis Of Desferrioxamine Siderophores Initiated By Decarboxylases: A Functional Investigation Of Two Lysine/Ornithine-Decarboxylases From Gordonia Rubripertincta Cwb2 And Pimelobacter Simplex Vkm Ac-2033d” [Arch. Biochem. Biophys. 689 (2020) 108429] (Archives Of Biochemistry And Biophysics (2020) 689, (S0003986120304380), (10.1016/J.Abb.2020.108429)), Marika Hofmann, Julia S. Martin Del Campo, Pablo Sobrado, Dirk Tischler
Chemistry Faculty Research & Creative Works
The authors regret that mistakenly the wrong strain was named in the article title. The decarboxylase gene psdesA originates from Pimelobacter simplex VKM Ac-2033D, not from Pimelobacter simplex 3E. The authors would like to apologize for any inconvenience caused.
Competition Between Solvent-Solvent And Solvent-Solute Interactions In The Microhydration Of The Hexafluorophosphate Anion, Pf6⁻(H2o)N=1,2, Yasmeen A. Abdo, Gregory S. Tschumper
Competition Between Solvent-Solvent And Solvent-Solute Interactions In The Microhydration Of The Hexafluorophosphate Anion, Pf6⁻(H2o)N=1,2, Yasmeen A. Abdo, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
This study systematically examines the interactions of the hexafluorophosphate anion (PF6-) with one or two solvent water molecules (PF6-(H2O)n where n = 1, 2). Full geometry optimizations and subsequent harmonic vibrational frequency computations are performed on each stationary point using a variety of common density functional theory methods (B3LYP, B3LYP-D3, M06-2X, and ωB97XD) and the MP2 and CCSD(T) ab initio methods with a triple-ζ correlation consistent basis set augmented with diffuse functions on all non-hydrogen atoms (cc-pVTZ for H and aug-cc-pVTZ for P, O, and F; denoted as haTZ). Five new stationary …
Trapping Conformational States Of A Flavin-Dependent N-Monooxygenase In Crystallo Reveals Protein And Flavin Dynamics, Ashley C. Campbell, Kyle M. Stiers, Julia S. Martin Del Campo, Ritcha Mehra-Chaudhary, Pablo Sobrado, John J. Tanner
Trapping Conformational States Of A Flavin-Dependent N-Monooxygenase In Crystallo Reveals Protein And Flavin Dynamics, Ashley C. Campbell, Kyle M. Stiers, Julia S. Martin Del Campo, Ritcha Mehra-Chaudhary, Pablo Sobrado, John J. Tanner
Chemistry Faculty Research & Creative Works
The siderophore biosynthetic enzyme A (SidA) ornithine hydroxylase from Aspergillus fumigatus is a fungal disease drug target involved in the production of hydroxamate-containing siderophores, which are used by the pathogen to sequester iron. SidA is an N-monooxygenase that catalyzes the NADPH-dependent hydroxylation of L-ornithine through a multistep oxidative mechanism, utilizing a C4a-hydroperoxyflavin intermediate. Here we present four new crystal structures of SidA in various redox and ligation states, including the first structure of oxidized SidA without NADP(H) or L-ornithine bound (resting state). The resting state structure reveals a new out active site conformation characterized by large rotations of the FAD …
Erratum: Basis Set Dependence Of Higher-Order Correlation Effects In Π -Type Interactions (J. Chem. Phys. (2012) 136 (014103) Doi: 10.1155/2019/4057848), Emily J. Carrell, Cara M. Thorne, Gregory S. Tschumper
Erratum: Basis Set Dependence Of Higher-Order Correlation Effects In Π -Type Interactions (J. Chem. Phys. (2012) 136 (014103) Doi: 10.1155/2019/4057848), Emily J. Carrell, Cara M. Thorne, Gregory S. Tschumper
Chemistry Faculty Research & Creative Works
For a sequence of three correlation consistent basis sets,1 an algebraic expression can be obtained from Feller's three-parameter exponential function for the complete basis set (CBS) limit of the Hartree–Fock (HF) energy.2 During the derivation of a general three-point algebraic expression for the HF CBS limit,3 it was recognized that Eq. (2) in our original paper4 had the wrong sign in the last term in the denominator. The correct equation is as follows: (Formula Presented). (Table Presented).
Structure And Function Of A Flavin-Dependent S-Monooxygenase From Garlic (Allium Sativum), Hannah Valentino, Ashley C. Campbell, Jonathan P. Schuermann, Nazneen Sultana, Han G. Nam, Sophie Leblanc, John J. Tanner, Pablo Sobrado
Structure And Function Of A Flavin-Dependent S-Monooxygenase From Garlic (Allium Sativum), Hannah Valentino, Ashley C. Campbell, Jonathan P. Schuermann, Nazneen Sultana, Han G. Nam, Sophie Leblanc, John J. Tanner, Pablo Sobrado
Chemistry Faculty Research & Creative Works
Allicin is a component of the characteristic smell and flavor of garlic (Allium sativum). A flavin-containing monooxygenase (FMO) produced by A. sativum (AsFMO) was previously proposed to oxidize S-allyl-L-cysteine (SAC) to alliin, an allicin precursor. Here, we present a kinetic and structural characterization of AsFMO that suggests a possible contradiction to this proposal. Results of steady-state kinetic analyses revealed that AsFMO exhibited negligible activity with SAC; however, the enzyme was highly active with L-cysteine, N-acetyl-L-cysteine, and allyl mercaptan. We found that allyl mercaptan with NADPH was the preferred substrate-cofactor combination. Rapid-reaction kinetic analyses showed that NADPH binds tightly (KD of …
Effect Of Vortex-Induced Physical Stress On Fluorescent Properties Of Dye-Containing Poly(Ethylene Glycol)-Block-Poly(Lactic Acid) Micelles, Tyler L. Odom, Jacob R. Blankenship, Giselle Campos, Devin C. Mart, Wenyan Liu, Risheng Wang, Keiichi Yoshimatsu
Effect Of Vortex-Induced Physical Stress On Fluorescent Properties Of Dye-Containing Poly(Ethylene Glycol)-Block-Poly(Lactic Acid) Micelles, Tyler L. Odom, Jacob R. Blankenship, Giselle Campos, Devin C. Mart, Wenyan Liu, Risheng Wang, Keiichi Yoshimatsu
Chemistry Faculty Research & Creative Works
The effect of vortex-induced mechanical stresses on the fluorescent properties of dye-containing poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA) block copolymer micelles has been investigated. PEG-b-PLA block copolymer micelles containing fluorescent dyes, 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO) and/or 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI), are prepared by a simple one-step procedure that involves the self-assembly of block copolymers and spontaneous incorporation of hydrophobic dyes into the core of the micelles. Upon vortexing, the micelle dispersion samples showed a decrease in fluorescence intensity in a rotational speed- and time-dependent manner. The results demonstrated that the vortexing can alter the fluorescent properties of the dye-containing PEG-b-PLA block copolymer micelle dispersion …
Postharvest Application Of Thiol Compounds Affects Surface Browning And Antioxidant Activity Of Fresh-Cut Potatoes, İnci Cerit, Annalise Pfaff, Nuran Ercal, Omca Demirkol
Postharvest Application Of Thiol Compounds Affects Surface Browning And Antioxidant Activity Of Fresh-Cut Potatoes, İnci Cerit, Annalise Pfaff, Nuran Ercal, Omca Demirkol
Chemistry Faculty Research & Creative Works
The aim of this study was to compare the effects of sodium metabisulphite and the thiol compounds, glutathione (GSH), L-cysteine (CYS), and N-acetylcysteine (NAC), on the enzymatic browning, antioxidant activities, total phenolic, and ascorbic acid content of potatoes after 1, 24, and 48 hr. Three different concentrations (0.5%, 1.0%, and 2.0%) of each thiol compound were tested. While sulphite solution inhibited polyphenol oxidase as expected, NAC and CYS also decreased its activity. CYS-treated samples exhibited the highest residual thiol content, while the amount of residual thiol in GSH-treated samples was the lowest. The 2.0% NAC and 2.0% CYS solutions were …