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Articles 1 - 30 of 34
Full-Text Articles in Physical Sciences and Mathematics
The Electronic Properties Of Ni(Pnn) Pincer Complexes Modulate Activity In Catalytic Hydrodehalogenation Reactions, Denan Wang, James R. Gardinier
The Electronic Properties Of Ni(Pnn) Pincer Complexes Modulate Activity In Catalytic Hydrodehalogenation Reactions, Denan Wang, James R. Gardinier
Chemistry Faculty Research and Publications
Three chloronickel(II) complexes of PNN‐ pincer ligands with pyrazolyl and diphenylphosphino donors appended to different arms of diarylamido anchors were prepared and fully characterized. The three derivatives (1‐OMe, 1‐Me, 1‐CF3) differ only by the identity of the para‐aryl substituent on the pyrazolyl arm with 1‐OMe being 310 mV easier to oxidize than 1‐CF3. All three complexes are competent catalysts for hydrodehalogenation reactions of 1‐bromooctane and a variety of aryl halides in dimethylacetamide using NaBH4 as both base and hydride source. Comparative studies using diverse substrates showed that catalytic activity correlates with electron donor properties; …
Iron(Iii)-Bipyridine Incorporated Metal–Organic Frameworks For Photocatalytic Reduction Of Co2 With Improved Performance, Yuan-Ping Wei, Sizhuo Yang, Peng Wang, Jin-Han Guo, Jier Huang, Wei-Yin Sun
Iron(Iii)-Bipyridine Incorporated Metal–Organic Frameworks For Photocatalytic Reduction Of Co2 With Improved Performance, Yuan-Ping Wei, Sizhuo Yang, Peng Wang, Jin-Han Guo, Jier Huang, Wei-Yin Sun
Chemistry Faculty Research and Publications
Metal–organic frameworks (MOFs) represent an emerging class of platforms to assemble single site photocatalysts for artificial photosynthesis. In this work, we report a new CO2 reduction photocatalyst (UiO-68-Fe-bpy) based on a robust Zr(IV)-MOF platform with incorporated Fe(bpy)Cl3 (bpy refers to the 4′-methyl-[2,2′-bipyridine] moiety) via amine–aldehyde condensation. We show that this hybrid catalyst can reduce CO2 to form CO under visible light illumination with excellent selectivity and enhanced activity with respect to its parent MOF and corresponding homogeneous counterpart. Using steady state and transient absorption (TA) spectroscopy, we show that the enhanced photocatalytic activity of UiO-68-Fe-bpy is attributed …
P450 Cyp17a1 Variant With A Disordered Proton Shuttle Assembly Retains Peroxo-Mediated Lyase Efficiency, Yilin Liu, Ilia G. Denisov, Yelena V. Grinkova, Stephen G. Silgar, James R. Kincaid
P450 Cyp17a1 Variant With A Disordered Proton Shuttle Assembly Retains Peroxo-Mediated Lyase Efficiency, Yilin Liu, Ilia G. Denisov, Yelena V. Grinkova, Stephen G. Silgar, James R. Kincaid
Chemistry Faculty Research and Publications
Human cytochrome P450 CYP17A1 first catalyzes hydroxylation at the C17 position of either pregnenolone (PREG) or progesterone (PROG), and a subsequent C17−C20 bond scission to produce dehydroepiandrosterone (DHEA) or androstenedione (AD). In the T306A mutant, replacement of the Threonine 306 alcohol functionality, essential for efficient proton delivery in the hydroxylase reaction, has only a small effect on the lyase activity. In this work, resonance Raman spectroscopy is employed to provide crucial structural insight, confirming that this mutant, with its disordered proton shuttle, fails to generate essential hydroxylase pathway intermediates, accounting for the loss in hydroxylase efficiency. Significantly, …
Probing The Magnetic Anisotropy Of Co(Ii) Complexes Featuring Redox-Active Ligands, Praveen Kumar, Daniel J. Santa Lucia, Kinga Kaniewska-Laskowska, Sergey Lindeman, Andrew Ozarowski, J. Krzystek, Mykhaylo Ozerov, Joshua Telser, John F. Berry, Adam T. Fiedler
Probing The Magnetic Anisotropy Of Co(Ii) Complexes Featuring Redox-Active Ligands, Praveen Kumar, Daniel J. Santa Lucia, Kinga Kaniewska-Laskowska, Sergey Lindeman, Andrew Ozarowski, J. Krzystek, Mykhaylo Ozerov, Joshua Telser, John F. Berry, Adam T. Fiedler
Chemistry Faculty Research and Publications
Coordination complexes that possess large magnetic anisotropy (otherwise known as zero-field splitting, ZFS) have possible applications in the field of magnetic materials, including single molecule magnets (SMMs). Previous studies have explored the role of coordination number and geometry in controlling the magnetic anisotropy and SMM behavior of high-spin (S = 3/2) Co(II) complexes. Building upon these efforts, the present work examines the impact of ligand oxidation state and structural distortions on the spin states and ZFS parameters of pentacoordinate Co(II) complexes. The five complexes included in this study (1–5) have the general formula, [Co(TpPh2 …
Copper-Catalyzed Formal Transfer Hydrogenation/Deuteration Of Aryl Alkynes, Samantha E. Sloane, Albert Reyes, Zoua Pa Vang, Lingzi Li, Kiera T. Behlow, Joseph R. Clark
Copper-Catalyzed Formal Transfer Hydrogenation/Deuteration Of Aryl Alkynes, Samantha E. Sloane, Albert Reyes, Zoua Pa Vang, Lingzi Li, Kiera T. Behlow, Joseph R. Clark
Chemistry Faculty Research and Publications
A copper-catalyzed reduction of alkynes to alkanes and deuterated alkanes is described under transfer hydrogenation and transfer deuteration conditions. Commercially available alcohols and silanes are used interchangeably with their deuterated analogues as the hydrogen or deuterium sources. Transfer deuteration of terminal and internal aryl alkynes occurs with high levels of deuterium incorporation. Alkyne-containing complex natural product analogues undergo transfer hydrogenation and transfer deuteration selectively, in high yield. Mechanistic experiments support the reaction occurring through a cis-alkene intermediate and demonstrate the possibility for a regioselective alkyne transfer hydrodeuteration reaction.
Ion Pairing Versus Solvation Of Dinitrobenzene Anions In Room-Temperature Ionic Liquids (Rtils): Vibrational Signatures Of Rtil–Substrate Interactions, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan
Ion Pairing Versus Solvation Of Dinitrobenzene Anions In Room-Temperature Ionic Liquids (Rtils): Vibrational Signatures Of Rtil–Substrate Interactions, Abderrahman Atifi, Piotr J. Mak, Michael D. Ryan
Chemistry Faculty Research and Publications
The mechanism of solvation of ions by ionic liquids is more complex than solvation in most molecular solvents as the ionic liquid itself provides the counter ion. Solvation and ion pairing of anionic substrates in room-temperature ionic liquids (RTILs) were investigated using resonance Raman spectroscopy and DFT calculations. The purpose of this study was to differentiate between the formation of discrete cation/anion structures and a double-layer cloud of counter ions without specific atomic interactions between the ionic species. In acetonitrile/RTIL mixtures, the radical anion and dianion of dinitrobenzene (DNB) are stabilized by RTILs through solvation and ion pairing. The formation …
Efficient Filters For Geometric Intersection Computations Using Gpu, Yiming Liu, Satish Puri
Efficient Filters For Geometric Intersection Computations Using Gpu, Yiming Liu, Satish Puri
Computer Science Faculty Research and Publications
Geometric intersection algorithms are fundamental in spatial analysis in Geographic Information System (GIS). Applying high performance computing to perform geometric intersection on huge amount of spatial data to get real-time results is necessary. Given two input geometries (polygon or polyline) of a candidate pair, we introduce a new two-step geospatial filter that first creates sketches of the geometries and uses it to detect workload and then refines the sketches by the common areas of sketches to decrease the overall computations in the refine phase. We call this filter PolySketch-based CMBR (PSCMBR) filter. We show the application of this filter in …
Solving Complex Eigenvalue Problems On A Quantum Annealer With Applications To Quantum Scattering Resonances, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Solving Complex Eigenvalue Problems On A Quantum Annealer With Applications To Quantum Scattering Resonances, Alexander Teplukhin, Brian K. Kendrick, Dmitri Babikov
Chemistry Faculty Research and Publications
Quantum computing is a new and rapidly evolving paradigm for solving chemistry problems. In previous work, we developed the Quantum Annealer Eigensolver (QAE) and applied it to the calculation of the vibrational spectrum of a molecule on the D-Wave quantum annealer. However, the original QAE methodology was applicable to real symmetric matrices only. For many physics and chemistry problems, the diagonalization of complex matrices is required. For example, the calculation of quantum scattering resonances can be formulated as a complex eigenvalue problem where the real part of the eigenvalue is the resonance energy and the imaginary part is proportional to …
Unravelling A Long-Lived Ligand-To-Metal Cluster Charge Transfer State In Ce–Tcpp Metal Organic Frameworks, Sizhou Yang, Wenhui Hu, James Nayakuchena, Christian Fiankor, Cunming Liu, Eli Diego Kinigstein, Jian Zhang, Xiaoyi Zhang, Jier Huang
Unravelling A Long-Lived Ligand-To-Metal Cluster Charge Transfer State In Ce–Tcpp Metal Organic Frameworks, Sizhou Yang, Wenhui Hu, James Nayakuchena, Christian Fiankor, Cunming Liu, Eli Diego Kinigstein, Jian Zhang, Xiaoyi Zhang, Jier Huang
Chemistry Faculty Research and Publications
Metal organic frameworks (MOFs) have emerged as promising photocatalytic materials for solar energy conversion. However, a fundamental understanding of light harvesting and charge separation (CS) dynamics in MOFs remains underexplored, yet they are key factors that determine the efficiency of photocatalysis. Herein, we report the design and CS dynamics of the Ce–TCPP MOF using ultrafast spectroscopic methods.
Distance Dependent Energy Transfer Dynamics From A Molecular Donor To A Zeolitic Imidazolate Framework Acceptor, Wenhui Hu, Fan Yang, Nick Pietraszak, Jing Gu, Jier Huang
Distance Dependent Energy Transfer Dynamics From A Molecular Donor To A Zeolitic Imidazolate Framework Acceptor, Wenhui Hu, Fan Yang, Nick Pietraszak, Jing Gu, Jier Huang
Chemistry Faculty Research and Publications
Zeolitic Imidazolate frameworks (ZIFs) have been demonstrated as promising light harvesting and photocatalytic materials for solar energy conversion. To facilitate their application in photocatalysis, it is essential to develop a fundamental understanding of their light absorption properties and energy transfer dynamics. In this work, we report distance-dependent energy transfer dynamics from a molecular photosensitizer (RuN3) to ZIF-67, where the distance between RuN3 and ZIF-67 is finely tuned by depositing an ultrathin Al2O3 layer on the ZIF-67 surface using an atomic layer deposition (ALD) method. We show that energy transfer time decreases with increasing distance between RuN3 and …
Solving The Conundrum: Widespread Proteins Annotated For Urea Metabolism In Bacteria Are Carboxyguanidine Deiminases Mediating Nitrogen Assimilation From Guanidine, Nicholas O. Schneider, Lambros J. Tassoulas, Danyun Zeng, Amanda J. Laseke, Nicholas J. Reiter, Lawrence P. Wackett, Martin St. Maurice
Solving The Conundrum: Widespread Proteins Annotated For Urea Metabolism In Bacteria Are Carboxyguanidine Deiminases Mediating Nitrogen Assimilation From Guanidine, Nicholas O. Schneider, Lambros J. Tassoulas, Danyun Zeng, Amanda J. Laseke, Nicholas J. Reiter, Lawrence P. Wackett, Martin St. Maurice
Chemistry Faculty Research and Publications
Free guanidine is increasingly recognized as a relevant molecule in biological systems. Recently, it was reported that urea carboxylase acts preferentially on guanidine, and consequently, it was considered to participate directly in guanidine biodegradation. Urea carboxylase combines with allophanate hydrolase to comprise the activity of urea amidolyase, an enzyme predominantly found in bacteria and fungi that catalyzes the carboxylation and subsequent hydrolysis of urea to ammonia and carbon dioxide. Here, we demonstrate that urea carboxylase and allophanate hydrolase from Pseudomonas syringae are insufficient to catalyze the decomposition of guanidine. Rather, guanidine is decomposed to ammonia through the combined activities of …
Computationally-Guided Investigation Of Dual Amine/Pi Lewis Acid Catalysts For Direct Additions Of Aldehydes And Ketones To Unactivated Alkenes And Alkynes, Eric Greve, Jacob D. Porter, Chris Dockendorff
Computationally-Guided Investigation Of Dual Amine/Pi Lewis Acid Catalysts For Direct Additions Of Aldehydes And Ketones To Unactivated Alkenes And Alkynes, Eric Greve, Jacob D. Porter, Chris Dockendorff
Chemistry Faculty Research and Publications
Dual amine/pi Lewis acid catalyst systems have been reported for intramolecular direct additions of aldehydes/ketones to unactivated alkynes and occasionally alkenes, but related intermolecular reactions are rare and not presently of significant synthetic utility, likely due to undesired coordination of enamine intermediates to the metal catalyst. We reasoned that bulky metal ligands and bulky amine catalysts could minimize catalyst poisoning and could facilitate certain examples of direct intermolecular additions of aldehydes/ketones to alkenes/alkynes. Density Functional Theory (DFT) calculations were performed that suggested that pyridine-2,6-bis(oxazoline) (PyBOX)-Pt(II) catalysts for alkene/alkyne activation could be combined with MacMillan's imidazolidinone organocatalyst for aldehyde/ketone activation to …
Resonance Raman Spectroscopic Studies Of Peroxo And Hydroperoxo Intermediates In Lauric Acid (La)-Bound Cytochrome P450 119, Remigio Usai, Daniel Kaluka, Piotr J. Mak, Yilin Liu, James R. Kincaid
Resonance Raman Spectroscopic Studies Of Peroxo And Hydroperoxo Intermediates In Lauric Acid (La)-Bound Cytochrome P450 119, Remigio Usai, Daniel Kaluka, Piotr J. Mak, Yilin Liu, James R. Kincaid
Chemistry Faculty Research and Publications
Cytochromes P450 bind and cleave dioxygen to generate a potent intermediate compound I, capable of hydroxylating inert hydrocarbon substrates. Cytochrome P450 119, a bacterial cytochrome P450 that serves as a good model system for the study of the intermediate states in the P450 catalytic cycle. CYP119 is found in high temperature and sulfur rich environments. Though the natural substrate and redox partner are still unknown, a potential application of such thermophilic P450s is utilizing them as biocatalysts in biotechnological industry; e.g., the synthesis of organic compounds otherwise requiring hostile environments like extremes of pH or temperature. In the present work …
Mqct: User-Ready Program For Calculations Of Inelastic Scattering Of Two Molecules, Alexander Semenov, Bikramaditya Mandal, Dmitri Babikov
Mqct: User-Ready Program For Calculations Of Inelastic Scattering Of Two Molecules, Alexander Semenov, Bikramaditya Mandal, Dmitri Babikov
Chemistry Faculty Research and Publications
A program named MQCT is developed for calculations of rotationally and vibrationally inelastic scattering of molecules using the mixed quantum/classical theory approach. Calculations of collisions between two general asymmetric top rotors are now possible, which is a feature unavailable in other existing codes. Vibrational states of diatomic molecules can also be included in the basis set expansion, to carry out calculations of ro-vibrational excitation and quenching. Minimal input for the code assumes several defaults and is very simple, easy to set-up and run by non-experts. Multiple options, available for expert calculations, are listed in the Supplemental Information. The code is …
Probing Cooperativity In C–H⋯N And C–H⋯Π Interactions: Dissociation Energies Of Aniline⋯(Ch4)N (N = 1, 2) Van Der Waals Complexes From Resonant Ionization And Velocity Mapped Ion Imaging Measurements, James Makuvaza, John L. Loman, Damian L. Kokkin, Scott Reid
Probing Cooperativity In C–H⋯N And C–H⋯Π Interactions: Dissociation Energies Of Aniline⋯(Ch4)N (N = 1, 2) Van Der Waals Complexes From Resonant Ionization And Velocity Mapped Ion Imaging Measurements, James Makuvaza, John L. Loman, Damian L. Kokkin, Scott Reid
Chemistry Faculty Research and Publications
Recent studies of the weakly bound anisole⋯CH4 complex found a dual mode of binding, featuring both C/H⋯π and C/H⋯O noncovalent interactions. In this work, we examine the dissociation energies of related aniline⋯(CH4)n (n = 1, 2) van der Waals clusters, where both C/H⋯π and C/H⋯N interactions are possible. Using a combination of theory and experiments that include mass-selected two-color resonant two-photon ionization spectroscopy, two-color appearance potential (2CAP) measurements, and velocity-mapped ion imaging (VMI), we derive the dissociation energies of both complexes in the ground (S0), excited (S1), and cation radical (D …
Silver(I) And Copper(I) Complexes Of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates, Denan Wang, Fathiya Jahan, Kristin J. Meise, Sergey Lindeman, James R. Gardinier
Silver(I) And Copper(I) Complexes Of Semi‐Bulky Nitrogen‐Confused C‐Scorpionates, Denan Wang, Fathiya Jahan, Kristin J. Meise, Sergey Lindeman, James R. Gardinier
Chemistry Faculty Research and Publications
Two new sterically demanding nitrogen‐confused C‐scorpionate ligands with a bis(3,5‐diisopropylpyrazol‐1‐yl)methyl group bound to the 3‐ position of a normal pyrazole (HLiPr2) or an N‐toluenesulfonyl pyrazole (TsLiPr2) have been prepared. Reactions between the ligands (xLiPr2) and silver trifluoromethanesulfonate, AgOTf, gave four new compounds of the types [Ag(xLiPr2)](OTf) (x = Ts, 1a; x = H, 2a) or [Ag(xLiPr2)2](OTf) (x = Ts, 1b; x = H, 2b) depending on the initial metal:ligand ratio. Similarly, the reactions with [Cu(CH3CN)4](PF6 …
Electron Ratchets: State Of The Field And Future Challenges, Bryan Lau, Ofer Kedem
Electron Ratchets: State Of The Field And Future Challenges, Bryan Lau, Ofer Kedem
Chemistry Faculty Research and Publications
Electron ratchets are non-equilibrium electronic devices that break inversion symmetry to produce currents from non-directional and random perturbations, without an applied net bias. They are characterized by strong parameter dependence, where small changes in operating conditions lead to large changes in the magnitude and even direction of the resulting current. This high sensitivity makes electron ratchets attractive research subjects, but leads to formidable challenges in their deeper study, and particularly to their useful application. This perspective reviews the progress that was made in the field starting from the first experimental electron ratchets in the late 1990s, and how the field …
Catalytic Carbon–Carbon Bond Activation Of Saturated And Unsaturated Carbonyl Compounds Via Chelate-Assisted Coupling Reaction With Indoles, Nuwan Asanka Pannilawithana, Chae S. Yi
Catalytic Carbon–Carbon Bond Activation Of Saturated And Unsaturated Carbonyl Compounds Via Chelate-Assisted Coupling Reaction With Indoles, Nuwan Asanka Pannilawithana, Chae S. Yi
Chemistry Faculty Research and Publications
The chelate assistance strategy was devised to promote a highly regioselective catalytic C–C bond activation reaction of saturated and unsaturated carbonyl compounds. The cationic Ru–H complex 1 was found to be an effective catalyst for mediating the coupling reaction of 1,2-disubstituted indoles with α,β-unsaturated aldehydes and ketones, in which the regioselective Cα–Cβ activation of the carbonyl substrates has been achieved in forming the 3-alkylindole products. The analogous coupling reaction of indoles with saturated aldehydes and ketones directly led to the Cα–Cβ cleavage of the carbonyl substrates in forming the 3-alkylindole products. The coupling reaction …
Modified Synthesis Of The Peptidomimetic Natriuretic Peptide Receptor-C Antagonist M372049, Jacob Porter, Sergey V. Lindeman, Chris Dockendorff
Modified Synthesis Of The Peptidomimetic Natriuretic Peptide Receptor-C Antagonist M372049, Jacob Porter, Sergey V. Lindeman, Chris Dockendorff
Chemistry Faculty Research and Publications
The Natriuretic Peptide Receptors (NPRs) regulate vascular sodium levels and have been of significant interest for the potential treatment of hypertension and related cardiovascular complications. The peptidomimetic antagonist M372049 is a valuable probe for the study of NPR-C signaling, unfortunately it is presently not commercially available. Described is a detailed protocol for its synthesis that does not require specialized apparatus and builds upon a prior patent from Veale and colleagues. Key steps include a base-mediated lactam formation and a solid-supported peptide synthetic sequence. An X-ray crystal structure of a key lactam intermediate was obtained to confirm the structure and relative …
Restructuring A General College Chemistry Sequence Using The Acs Anchoring Concepts Content Map, Scott Reid
Restructuring A General College Chemistry Sequence Using The Acs Anchoring Concepts Content Map, Scott Reid
Chemistry Faculty Research and Publications
Many STEM (science, technology, engineering, and mathematics) disciplines require a two-semester sequence of introductory college chemistry, which are thus critical gateway courses to a variety of majors. Recognizing the benefit to educators of a structure of content learning across the chemistry curriculum, in 2012, the American Chemical Society (ACS) developed the Anchoring Concepts Content Map, or ACCM. The development and subsequent revision of the general chemistry ACCM inspired the restructuring of our first-year chemistry sequence. Thus our CHEM 1001 and 1002 courses, taught in an atoms-first framework, were reorganized into a set of nine modules, each intentionally linked to one …
Tuning Internal Strain In Metal–Organic Frameworks Via Vapor Phase Infiltration For Co2 Reduction, Fan Yang, Wenhui Hu, Chongqing Yang, Margaret Patrick, Andrew L. Cooksy, Jian Zhang, Jeffery A. Aguiar, Chengcheng Fang, Yinghua Zhou, Ying Shirley Meng, Jier Huang, Jing Gu
Tuning Internal Strain In Metal–Organic Frameworks Via Vapor Phase Infiltration For Co2 Reduction, Fan Yang, Wenhui Hu, Chongqing Yang, Margaret Patrick, Andrew L. Cooksy, Jian Zhang, Jeffery A. Aguiar, Chengcheng Fang, Yinghua Zhou, Ying Shirley Meng, Jier Huang, Jing Gu
Chemistry Faculty Research and Publications
A gas-phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor-phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution-phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO2 to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element-specific X-ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square-pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn-OH2 bond in the axial plane. The …
Infrared Spectroelectrochemistry Of Iron-Nitrosyl Triarylcorroles. Implications For Ligand Noninnocence, Md. Hafizur Rahman, Michael D. Ryan, Hugo Vazquez-Lima, Abraham Alemayehu, Abhik Ghosh
Infrared Spectroelectrochemistry Of Iron-Nitrosyl Triarylcorroles. Implications For Ligand Noninnocence, Md. Hafizur Rahman, Michael D. Ryan, Hugo Vazquez-Lima, Abraham Alemayehu, Abhik Ghosh
Chemistry Faculty Research and Publications
Recent DFT calculations have suggested that iron nitrosyl triarylcorrole complexes have substantial {FeNO}7–corrole•2– character. With this formulation, reduction of Fe(C)(NO) complexes, where C = triarylcorrole, should be centered on the corrole macrocycle rather than on the {FeNO}7 moiety. To verify this proposition, visible and infrared spectroelectrochemical studies of Fe(C)(NO) were carried out and the results were interpreted using DFT (B3LYP/STO-TZP) calculations. The first reduction of Fe(C)(NO) led to significant changes in the Soret and Q-band regions of the visible spectrum as well as to a significant downshift in the νNO and changes in the corrole …
Sufficient Dimension Folding In Regression Via Distance Covariance For Matrix‐Valued Predictors, Wenhui Sheng, Qingcong Yuan
Sufficient Dimension Folding In Regression Via Distance Covariance For Matrix‐Valued Predictors, Wenhui Sheng, Qingcong Yuan
Mathematical and Statistical Science Faculty Research and Publications
In modern data, when predictors are matrix/array‐valued, building a reasonable model is much more difficult due to the complicate structure. However, dimension folding that reduces the predictor dimensions while keeps its structure is critical in helping to build a useful model. In this paper, we develop a new sufficient dimension folding method using distance covariance for regression in such a case. The method works efficiently without strict assumptions on the predictors. It is model‐free and nonparametric, but neither smoothing techniques nor selection of tuning parameters is needed. Moreover, it works for both univariate and multivariate response cases. In addition, we …
Unraveling The Intermediate Species Of Co3O4 Hollow Spheres For Co2 Photoreduction By In Situ X-Ray Absorption Spectroscopy, Peilei He, Sizhou Yang, Wenhui Hu, Sungsik Lee, Jier Huang
Unraveling The Intermediate Species Of Co3O4 Hollow Spheres For Co2 Photoreduction By In Situ X-Ray Absorption Spectroscopy, Peilei He, Sizhou Yang, Wenhui Hu, Sungsik Lee, Jier Huang
Chemistry Faculty Research and Publications
Nanostructured hollow materials have emerged as a promising class of materials for energy conversion and storage. In this work, we report a Co3O4 hollow sphere nanostructure that can serve as a CO2 reduction catalyst to form CO with high selectivity upon visible-light illumination in the presence of a [Ru(bpy)3]2+ molecular photosensitizer. Using in situ X-ray absorption spectroscopy, we not only showed that the Co center in the Co3O4 hollow sphere is the active site for CO2 reduction but also identified a key intermediate species, that is, a reduced Co …
Cosmic: Us-Based Conversion Master's Degree In Computing, Gary S. Krenz, Thomas Kaczmarek
Cosmic: Us-Based Conversion Master's Degree In Computing, Gary S. Krenz, Thomas Kaczmarek
Mathematical and Statistical Science Faculty Research and Publications
COSMIC is an NSF S-STEM graduate curriculum initiative/conversion program that strives to provide an accelerated pathway to a Master of Science (MS) degree for individuals who do not have an undergraduate degree in computing, but who wish to cross over into the computing field. The structure of our conversion program, the context that motivated it, and insights from conversion students' instructors are presented. Program successes with students from under-represented populations and the limitations that are also experienced are discussed. Our conversion program is based on a highly focused summer bridge course, combined with a customized curriculum pathway that enables people …
Adiabatic Trajectory Approximation Within The Framework Of Mixed Quantum/Classical Theory, Bikramaditya Mandal, Alexander Semenov, Dmitri Babikov
Adiabatic Trajectory Approximation Within The Framework Of Mixed Quantum/Classical Theory, Bikramaditya Mandal, Alexander Semenov, Dmitri Babikov
Chemistry Faculty Research and Publications
A hierarchy of approximate methods is proposed for solving the equations of motion within a framework of the mixed quantum/classical theory (MQCT) of inelastic molecular collisions. Of particular interest is a limiting case: the method in which the classical-like equations of motion for the translational degrees of freedom (scattering) are decoupled from the quantum-like equations for time evolution of the internal molecular states (rotational and vibrational). In practice, trajectories are pre-computed during the first step of calculations with driving forces determined solely by the potential energy surface of the entrance channel, which is an adiabatic trajectory approximation. Quantum state-to-state transition …
Enhanced Light Harvesting Ability In Zeolitic Imidazolate Frameworks Through Energy Transfer From Cds Nanowires, Yixuan Zhou, Wenhui Hu, Sizhuo Yang, Jier Huang
Enhanced Light Harvesting Ability In Zeolitic Imidazolate Frameworks Through Energy Transfer From Cds Nanowires, Yixuan Zhou, Wenhui Hu, Sizhuo Yang, Jier Huang
Chemistry Faculty Research and Publications
Zeolitic imidazolate frameworks (ZIFs) represent a novel class of porous crystalline materials that have demonstrated potential as light harvesting materials for solar energy conversion. In order to facilitate their application in solar energy conversion, it is necessary to expand their absorption further into the realm of the solar spectrum. In this work, we report the incorporation of semiconductor cadmium sulfide nanowires (CdS NWs) into ZIF-67 (CdS@ZIF-67), where a broader region of the solar spectrum can be absorbed by CdS NWs and relayed to ZIF-67 through an energy transfer (EnT) process. Using steady-state emission and time resolved emission and absorption spectroscopy, …
The Marshall-Olkin Exponentiated Generalized G Family Of Distributions: Properties, Applications, And Characterizations, Haitham M. Yousof, Mahdi Rasekhi, Morad Alizadeh, Gholamhossein Hamedani
The Marshall-Olkin Exponentiated Generalized G Family Of Distributions: Properties, Applications, And Characterizations, Haitham M. Yousof, Mahdi Rasekhi, Morad Alizadeh, Gholamhossein Hamedani
Mathematical and Statistical Science Faculty Research and Publications
In this paper, we propose and study a new class of continuous distributions called the Marshall-Olkin exponentiated generalized G (MOEG-G) family which extends the Marshall-Olkin-G family introduced by Marshall and Olkin [A. W. Marshall, I. Olkin, Biometrika 84 (1997), 641-652]. Some of its mathematical properties including explicit expressions for the ordinary and incomplete moments, generating function, order statistics and probability weighted moments are derived. Some characteristics of the new family are presented. Maximum likelihood estimation for the model parameters under uncensored and censored data is addressed in Section 5 as well as a simulation study to assess the performance of …
The Poisson Topp Leone Generator Of Distributions For Lifetime Data: Theory, Characterizations And Applications, Faton Merovci, Haitham M. Yousof, Gholamhossein Hamedani
The Poisson Topp Leone Generator Of Distributions For Lifetime Data: Theory, Characterizations And Applications, Faton Merovci, Haitham M. Yousof, Gholamhossein Hamedani
Mathematical and Statistical Science Faculty Research and Publications
We study a new family of distributions defined by the minimum of the Poisson random number of independent identically distributed random variables having a Topp Leone-G distribution (see Rezaei et al., (2016)). Some mathematical properties of the new family including ordinary and incomplete moments, quantile and generating functions, mean deviations, order statistics, reliability and entropies are derived. Maximum likelihood estimation of the model parameters is investigated. Some special models of the new family are discussed. An application is carried out on real data set applications sets to show the potentiality of the proposed family.
Voltammetry And Spectroelectrochemistry Of Tcnq In Acetonitrile/Rtil Mixtures, Abderrahman Atifi, Michael D. Ryan
Voltammetry And Spectroelectrochemistry Of Tcnq In Acetonitrile/Rtil Mixtures, Abderrahman Atifi, Michael D. Ryan
Chemistry Faculty Research and Publications
Understanding the solvation and ion-pairing interactions of anionic substrates in room-temperature ionic liquids (RTIL) is key for the electrochemical applications of these new classes of solvents. In this work, cyclic voltammetry and visible and infrared spectroelectrochemistry of tetracyanoquinodimethane (TCNQ) was examined in molecular (acetonitrile) and RTIL solvents, as well as mixtures of these solvents. The overall results were consistent with the formation of RTIL/acetonitrile nanodomains. The voltammetry indicated that the first electrogenerated product, TCNQ−, was not incorporated into the RTIL nanodomain, while the second electrogenerated product, TCNQ2−, was strongly attracted to the RTIL nanodomain. The visible …