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Articles 1 - 30 of 44
Full-Text Articles in Physical Sciences and Mathematics
Validation Of The Global Distribution Of Co2 Volume Mixing Ratio In The Mesosphere And Lower Thermosphere From Saber, L. Rezac, Y. Jian, J. Yue, J. M. Russell Iii, A. Kutepov, R. Garcia, K. Walker, P. Bernath
Validation Of The Global Distribution Of Co2 Volume Mixing Ratio In The Mesosphere And Lower Thermosphere From Saber, L. Rezac, Y. Jian, J. Yue, J. M. Russell Iii, A. Kutepov, R. Garcia, K. Walker, P. Bernath
Chemistry & Biochemistry Faculty Publications
The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite has been measuring the limb radiance in 10 broadband infrared channels over the altitude range from ~ 400 km to the Earth's surface since 2002. The kinetic temperatures and CO2 volume mixing ratios (VMRs) in the mesosphere and lower thermosphere have been simultaneously retrieved using SABER limb radiances at 15 and 4.3 μm under nonlocal thermodynamic equilibrium (non-LTE) conditions. This paper presents results of a validation study of the SABER CO2 VMRs obtained with a two-channel, self-consistent …
Hybrid Sol–Gel Glasses With Glass-Transition Temperatures Below Room Temperature, Andrei Jitianu, Guadalupe Gonzalez, Lisa C. Klein
Hybrid Sol–Gel Glasses With Glass-Transition Temperatures Below Room Temperature, Andrei Jitianu, Guadalupe Gonzalez, Lisa C. Klein
Publications and Research
Melting gels are hybrid gels that have the ability to soften and flow at around 100 ° C for some combinations of mono- and di-substituted alkoxysiloxanes, where substitutions are either all aromatic or all aliphatic. In this study, melting gels were prepared using phenyltriethoxysilane (PhTES) and dimethyldiethoxysilane (DMDES), meaning both an aromatic and aliphatic substitution. Differential scanning calorimetry was performed to identify glass-transition temperatures, and thermal gravimetric analysis coupled with differential thermal analysis (TGA-DTA) was performed to measure weight loss. The glass-transition temperatures ( T g ) ranged from – 61 ° C to + 5.6 ° C, which are …
Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi
Development Of A Two-Fluid Drag Law For Clustered Particles Using Direct Numerical Simulation And Validation Through Experiments, Ahmadreza Abbasi Baharanchi
FIU Electronic Theses and Dissertations
This dissertation focused on development and utilization of numerical and experimental approaches to improve the CFD modeling of fluidization flow of cohesive micron size particles. The specific objectives of this research were: (1) Developing a cluster prediction mechanism applicable to Two-Fluid Modeling (TFM) of gas-solid systems (2) Developing more accurate drag models for Two-Fluid Modeling (TFM) of gas-solid fluidization flow with the presence of cohesive interparticle forces (3) using the developed model to explore the improvement of accuracy of TFM in simulation of fluidization flow of cohesive powders (4) Understanding the causes and influential factor which led to improvements and …
The Influence Of The Proximal Amide Hydrogen Bonds And The Proximal Helix Dipole On The Catalytic Activity Of Chloroperoxidase, Armando D. Pardillo
The Influence Of The Proximal Amide Hydrogen Bonds And The Proximal Helix Dipole On The Catalytic Activity Of Chloroperoxidase, Armando D. Pardillo
FIU Electronic Theses and Dissertations
Chloroperoxidase (CPO) is a heme-thiolate protein with exceptional versatility and great potential as a biocatalyst. The CPO reactive species, Compound I ( Cpd I) is of particular interest, as well as the Cytochrome P450 (P450) -type monoxygenase catalytic activity, which has significant biotechnological potential. Proximal hydrogen bonding of the axial sulfur with the backbone amides (NH•••S) is a conserved feature of heme-thiolate enzymes. In CPO, the effect of NH•••S bonds is amplified by the dipole moment of the proximal helix. The role of the proximal region has been disputed as to whether it simply protects the axial sulfur, or whether …
Energy-Efficient Computational Chemistry: Comparison Of X86 And Arm Systems, Kristopher Keipert, Gaurav Mitra, Vaibhav Sunriyal, Sarom S. Leang, Masha Sosonkina, Alistair P. Rendell, Mark S. Gordon
Energy-Efficient Computational Chemistry: Comparison Of X86 And Arm Systems, Kristopher Keipert, Gaurav Mitra, Vaibhav Sunriyal, Sarom S. Leang, Masha Sosonkina, Alistair P. Rendell, Mark S. Gordon
Computational Modeling & Simulation Engineering Faculty Publications
The computational efficiency and energy-to-solution of several applications using the GAMESS quantum chemistry suite of codes is evaluated for 32-bit and 64-bit ARM-based computers, and compared to an x86 machine. The x86 system completes all benchmark computations more quickly than either ARM system and is the best choice to minimize time to solution. The ARM64 and ARM32 computational performances are similar to each other for Hartree-Fock and density functional theory energy calculations. However, for memory-intensive second-order perturbation theory energy and gradient computations the lower ARM32 read/write memory bandwidth results in computation times as much as 86% longer than on the …
Fused-Molecular Systems For Organic Light Emitting Diodes, Avinash Jami
Fused-Molecular Systems For Organic Light Emitting Diodes, Avinash Jami
Masters Theses & Specialist Projects
Organic light emitting diodes (OLEDs) are electronic devices made by sandwitching organic light emissive materials between two electrodes. When voltage is applied across the two conductors, a bright light is generated. The color of the emitting light depends on the band gap of the semiconducting material. The work described here focuses on designing and synthesizing narrow band gap molecular systems derived from fused-arene derivatives for producing organic blue light emitting diodes. Three molecular systems derived from anthracene, pyrene, and carbazole, were designed and synthesized. Two molecular systems of anthracen-9-ylmethyl anthracene-9- carboxylate and pyren-1-ylmethyl 4-bromobenzoate were synthesized through Steglich esterification reaction …
Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman
Heterogeneous Oxidation Of Catechol, Elizabeth A. Pillar, Ruixin Zhou, Marcelo I. Guzman
Chemistry Faculty Publications
Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air–solid interface under variable relative humidity (RH = 0–90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10–6 occurs for …
Characterization Of Folic Acid And Poly(Amidoamine) Dendrimer Interactions With Folate Binding Protein: A Force-Pulling Study, Pascale R. Leroueil, Stassi Dimaggio, Abigail N. Leistra, Craig D. Blanchette
Characterization Of Folic Acid And Poly(Amidoamine) Dendrimer Interactions With Folate Binding Protein: A Force-Pulling Study, Pascale R. Leroueil, Stassi Dimaggio, Abigail N. Leistra, Craig D. Blanchette
University Faculty Publications and Creative Works
Atomic force microscopy force-pulling experiments have been used to measure the binding forces between folic acid (FA) conjugated poly(amidoamine) (PAMAM) dendrimers and folate binding protein (FBP). The generation 5 (G5) PAMAM conjugates contained an average of 2.7, 4.7, and 7.2 FA per dendrimer. The most probable rupture force was measured to be 83, 201, and 189 pN for G5-FA2.7, G5-FA4.7, and G5-FA7.2, respectively. Folic acid blocking experiments for G5-FA7.2reduced the frequency of successful binding events and increased the magnitude of the average rupture force to 274 pN. The force data are interpreted as arising from a network of van der …
Fugacity Examples 2: The Fugacity Of A “Hard-Sphere” Semi-Ideal Gas And The Van Der Waals Gas, Carl W. David
Fugacity Examples 2: The Fugacity Of A “Hard-Sphere” Semi-Ideal Gas And The Van Der Waals Gas, Carl W. David
Chemistry Education Materials
The fugacity of the van der Waals gas is obtained after a review of the concept itself.
Errata For Tensor Of Moment Of Inertia (52) Manuscript, Carl W. David
Errata For Tensor Of Moment Of Inertia (52) Manuscript, Carl W. David
Chemistry Education Materials
An error in the manuscript (52) of this series is noted
Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner
Effect Of Surface Omniphobicity On Drying By Forced Convection, Madani A. Khan, Jeffrey Alston, Andrew Guenthner
STAR Program Research Presentations
Low energy surfaces can strongly repel both oil and water. Recently these surfaces have been fabricated on various substrates including fabric, aluminum, stainless steel and many other materials. In this experiment we explore the use of low energy surface deposition on aluminum alloy, stainless steel and silicon substrates, to enhance the drying rate of liquids removed from the surface by forced convection. We control surface roughness by substrate abrasion and by the growth of Al2O3 nanograss to enhance liquid repellence by use of a hierarchical texture. Liquid repellence of the substrates is measured by contact angles of …
Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert
Synthesis And Flammability Testing Of Epoxy Functionalized Phosphorous-Based Flame Retardants, Vladimir Benin, Xuemei Cui, Alexander Morgan, Karl Seiwert
Chemistry Faculty Publications
Several potential new phosphorus-containing flame retardant molecules were evaluated for heat release reduction potential by incorporation of the molecules into a polyurethane, generated from methylene diphenyl diisocyanate and 1,3-propane diol. The heat release reduction potential of these substances was evaluated using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods to qualitatively evaluate their potential reactivity into the polyurethane prior to heat release testing. The functionality of the flame retardants was epoxide based that would potentially react with the diol during polyurethane synthesis. Flammability testing …
Gas-Phase Electron Diffraction From Laser-Aligned Molecules, Jie Yang, Martin Centurion
Gas-Phase Electron Diffraction From Laser-Aligned Molecules, Jie Yang, Martin Centurion
Martin Centurion Publications
Electron diffraction is a valuable tool to capture structural information from molecules in the gas phase. However, the information contained in the diffraction patterns is limited due to the random orientation of the molecules. Additional structural information can be retrieved if the molecules are aligned. Molecules can be impulsively aligned with femtosecond laser pulses, producing a transient alignment. The alignment persists only for a time on the order of a picosecond, so a pulsed electron gun is needed to record the diffraction patterns. In this manuscript, we describe the alignment process and show the changes in the diffraction pattern as …
Nanostructured Cerium Oxide Based Catalysts: Synthesis, Physical Properties, And Catalytic Performance, Yunyun Zhou
Nanostructured Cerium Oxide Based Catalysts: Synthesis, Physical Properties, And Catalytic Performance, Yunyun Zhou
Department of Chemistry: Dissertations, Theses, and Student Research
Cerium oxide is an extensively used industrial catalyst with applications as diverse as catalysts for automobile exhaust, petroleum cracking and organic chemicals synthesis. The catalytic activity of cerium oxide is dependent upon its structural properties, especially the oxygen vacancy defects. While recent advances in characterization techniques have dramatically improved our understanding of cerium oxide functionality, many atomic features in cerium oxide contributing to the overall catalytic reactivity are not yet well-understood. This dissertation focuses on the structural studies of catalytically active cerium oxides with different compositions, phases and morphologies, and their utilizations to establish fundamental understandings of cerium oxide based …
Thz-Pulse-Induced Selective Catalytic Co Oxidation On Ru, Jerry L. Larue, Tetsuo Katayama, Aaron Lindenberg, Alan S. Fisher, Henrik Öström, Anders Nilsson, Hirohito Ogasawara
Thz-Pulse-Induced Selective Catalytic Co Oxidation On Ru, Jerry L. Larue, Tetsuo Katayama, Aaron Lindenberg, Alan S. Fisher, Henrik Öström, Anders Nilsson, Hirohito Ogasawara
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We demonstrate the use of intense, quasi-half-cycle THz pulses, with an associated electric field component comparable to intramolecular electric fields, to direct the reaction coordinate of a chemical reaction by stimulating the nuclear motions of the reactants. Using a strong electric field from a THz pulse generated via coherent transition radiation from an ultrashort electron bunch, we present evidence that CO oxidation on Ru(0001) is selectively induced, while not promoting the thermally induced CO desorption process. The reaction is initiated by the motion of the O atoms on the surface driven by the electric field component of the THz pulse, …
Plotting The Van Der Waals Fluid In Pseudo-3d And The Maxwell Construction, Carl W. David
Plotting The Van Der Waals Fluid In Pseudo-3d And The Maxwell Construction, Carl W. David
Chemistry Education Materials
The van der Waals (from his thesis of 1873) equation is a cubic in the molar volume. Plotting the equation in pseudo 3 dimensions is quite simple to do, but including tie lines is quite difficult. Employing the solutions to the cubic van der Waals equation, the tie lines are readily available and can be easily incorporated into the aforementioned 3D plots.
A Ph Switchable Responsive Surface For The Trapping And Release Of A Hydrophobic Substance, Ali Esmail Karim
A Ph Switchable Responsive Surface For The Trapping And Release Of A Hydrophobic Substance, Ali Esmail Karim
Masters Theses & Specialist Projects
Solid phase extraction is one of the most widely used techniques to trap and release compounds in a solution. A hydrophobic substance will stick efficiently to a hydrophobic surface (the “like dissolves like” principle). With an introduced response (i.e. pH change), a responsive surface can change from hydrophobic to hydrophilic, weakening the hydrophobic substance’s attraction and thus facilitate in an easy removal. A surface has been prepared having a terminal anthranilic acid (AA) moiety on silica gel particles, microscope slides, and TLC plates in three steps. First, a vinyl group was attached to the surface. Then, this vinyl group was …
Titanium Trisulfide Monolayer: Theoretical Prediction Of A New Direct-Gap Semiconductor With High And Anisotropic Carrier Mobility, Jun Dai, Xiao Cheng Zeng
Titanium Trisulfide Monolayer: Theoretical Prediction Of A New Direct-Gap Semiconductor With High And Anisotropic Carrier Mobility, Jun Dai, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
A new two-dimensional (2D) layered material, namely, titanium trisulfide (TiS3) monolayer, is predicted to possess novel electronic properties. Ab initio calculations show that the perfect TiS3 monolayer is a direct-gap semiconductor with a bandgap of 1.02 eV, close to that of bulk silicon, and with high carrier mobility. More remarkably, the in-plane electron mobility of the 2D TiS3 is highly anisotropic, amounting to about 10,000 cm2 V−1 s−1 in the b direction, which is higher than that of the MoS2 monolayer, whereas the hole mobility is about two orders of magnitude lower. …
Growth In Stratospheric Chlorine From Short-Lived Chemicals Not Controlled By The Montreal Protocol, R. Hossaoni, M. P. Chipperfield, A. Saiz-Lopez, J. J. Harrison, R. Von Glasow, R. Sommariva, E. Atlas, M. Navarro, S. A. Montzka, W. Feng, P. F. Bernath
Growth In Stratospheric Chlorine From Short-Lived Chemicals Not Controlled By The Montreal Protocol, R. Hossaoni, M. P. Chipperfield, A. Saiz-Lopez, J. J. Harrison, R. Von Glasow, R. Sommariva, E. Atlas, M. Navarro, S. A. Montzka, W. Feng, P. F. Bernath
Chemistry & Biochemistry Faculty Publications
We have developed a chemical mechanism describing the tropospheric degradation of chlorine containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS (ClyVSLS) between 2005 and 2013. By constraining the model with surface measurements of chloroform (CHCl3), dichloromethane (CH2Cl2), tetrachloroethene (C2Cl4), trichloroethene (C2HCl3), and 1,2-dichloroethane (CH2ClCH2Cl), we infer a 2013 ClyVSLS mixing ratio of 123 parts per trillion (ppt). Stratospheric injection …
Corrosion Protection Of 304 Stainless Steel With Melting Gels Coatings, Mario Aparicio, Andrei Jitianu, Gabriela Rodriguez, Ahmad Dengah, Kutaiba Marzoki, Jadra Mosa, Lisa C. Klein
Corrosion Protection Of 304 Stainless Steel With Melting Gels Coatings, Mario Aparicio, Andrei Jitianu, Gabriela Rodriguez, Ahmad Dengah, Kutaiba Marzoki, Jadra Mosa, Lisa C. Klein
Publications and Research
Methyl-substituted melting gels were used to coat AISI 304 stainless steel substrates. Crack-free coatings up to 1 mm in thickness were obtained. SEM micrographs of cross-sections con fi rm good adhesion to the surface. Samples were subjected to structural characterization using FT-IR, and Raman spectroscopy. Mechanical properties were investigated by micro-scratch tests. Electrochemical analyses (anodic polarization and electrochemical impedance spectroscopy) were performed in 3.5% NaCl solutions. Electrochemical tests show excellent performance of the coatings against corrosion with no sign of degradation after several months of immersion.
Simulation Of Energetic Particle Precipitation Effects During The 2003-2004 Arctic Winter, C. E. Randall, V. L. Harvey, L. A. Holt, D. R. Marsh, D. Kinnison, B. Funke, P. F. Bernath
Simulation Of Energetic Particle Precipitation Effects During The 2003-2004 Arctic Winter, C. E. Randall, V. L. Harvey, L. A. Holt, D. R. Marsh, D. Kinnison, B. Funke, P. F. Bernath
Chemistry & Biochemistry Faculty Publications
Energetic particle precipitation (EPP) during the 2003-2004 Arctic winter led to the production and subsequent transport of reactive odd nitrogen (NOx=NO+NO2) from the mesosphere and lower thermosphere (MLT) into the stratosphere. This caused NOx enhancements in the polar upper stratosphere in April 2004 that were unprecedented in the satellite record. Simulations of the 2003-2004 Arctic winter with the Whole Atmosphere Community Climate Model using Specified Dynamics (SD-WACCM) are compared to satellite measurements to assess our understanding of the observed NOx enhancements. The comparisons show that SD-WACCM clearly displays the descent of NOx produced …
Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing
Green Chemistry As A Tool For Understanding The Toxic Substances Control Act: A Lecture Module For Undergraduate Students, Molly R. Blessing
Honors Scholar Theses
The Toxic Substances Control Act (TSCA) is the central form of chemical regulation existent in the United States today, yet scientists are often unaware or uncertain of its provisions. Violations of TSCA by unknowing chemists set industry and government unnecessarily at odds. A lecture on TSCA was developed for undergraduate students that uses the concept of green chemistry to promote interest and incentivize learning. Green chemistry methods are cleaner and less wasteful than traditional chemical ones, and many companies using them are at the forefront of technological innovation. The lecture explains both green chemistry and TSCA, includes company case studies, …
Corrosion Behaviors Of Coated Aluminum Alloys In Simulated Corrosive Environment, Jingyi Yue
Corrosion Behaviors Of Coated Aluminum Alloys In Simulated Corrosive Environment, Jingyi Yue
Masters Theses & Specialist Projects
This study investigated the corrosion of an aluminum alloy with and without coatings under simulated corrosive environments. Coatings were selected and applied from commercial materials and techniques, consisting of microceramic, epoxy primer, and topcoat. The experiments for coated specimens were carried out under various corrosive conditions, specifically, hydrodynamic flow, immersion in salt water and DI water, varying temperatures, and simulated sun light. The hydrodynamic conditions were simulated using a rotating cylinder electrode (RCE) with rotational speeds of 200, 400, 600, 800, and 1000 rpm. The immersion in saltwater and sunlight illumination tests were applied for 8 hours, and the simulated …
Syntheses, Structures And Properties Of Metal-Organic Frameworks, Xin Liu
Syntheses, Structures And Properties Of Metal-Organic Frameworks, Xin Liu
Masters Theses & Specialist Projects
Mercury is one of the most serious heavy metal pollution sources that threaten people’s health. For decades, people have developed many technologies and materials to capture mercury from flue gas of coal-fired plant. Currently, the most effective material for mercury absorption is powdered activated carbon, which shows increased efficiency when modified with halogen functional groups such as bromine. Metal-organic frameworks (MOFs) have potential applications in mercury capture due to their fantastic properties such as high porosity and high thermal stability. More important, their pore sizes and topology structures can be controlled through choosing different organic ligands in the syntheses. However, …
The Requisite Electronic Structure Theory To Describe Photoexcited Nonadiabatic Dynamics: Nonadiabatic Derivative Couplings And Diabatic Electronic Couplings, Joseph E. Subotnik, Ethan Alguire, Qi Ou, Brian R. Landry, Shervin Fatehi
The Requisite Electronic Structure Theory To Describe Photoexcited Nonadiabatic Dynamics: Nonadiabatic Derivative Couplings And Diabatic Electronic Couplings, Joseph E. Subotnik, Ethan Alguire, Qi Ou, Brian R. Landry, Shervin Fatehi
Chemistry Faculty Publications and Presentations
Conspectus
Electronically photoexcited dynamics are complicated because there are so many different relaxation pathways: fluorescence, phosphorescence, radiationless decay, electon transfer, etc. In practice, to model photoexcited systems is a very difficult enterprise, requiring accurate and very efficient tools in both electronic structure theory and nonadiabatic chemical dynamics. Moreover, these theoretical tools are not traditional tools. On the one hand, the electronic structure tools involve couplings between electonic states (rather than typical single state energies and gradients). On the other hand, the dynamics tools involve propagating nuclei on multiple potential energy surfaces (rather than the usual ground state dynamics).
In this …
Unraveling Structures Of Protection Ligands On Gold Nanoparticle Au68(Sh)32, Wen Wu Xu, Yi Gao, Xiao Cheng Zeng
Unraveling Structures Of Protection Ligands On Gold Nanoparticle Au68(Sh)32, Wen Wu Xu, Yi Gao, Xiao Cheng Zeng
Xiao Cheng Zeng Publications
New low-energy atomic structures of the thiolate-protected gold nanoparticle Au68(SH)32 are uncovered, where the atomic positions of the Au atoms are taken from the recent single-particle transmission electron microscopy measurement by Kornberg and co-workers, whereas the pattern of thiolate ligands on the gold core is attained on the basis of the generic formulation (or rule) of the “divide and protect” concept. Four distinct low-energy isomers, Iso1 to Iso4, whose structures all satisfy the generic formulation, are predicted. Density-functional theory optimization indicates that the four isomers are all lower in energy by 3 to 4 eV than the …
A Maltose-Binding Protein Fusion Construct Yields A Robust Crystallography Platform For Mcl1, Matthew C. Clifton, David M. Dranow, Alison Leed, Ben Fulroth, James W. Fairman, Jan Abendroth, Kateri A. Atkins, Ellen Wallace, Dazhong Fan, Guoping Xu, Z. J. Ni, Douglas S. Daniels, John Van Drie, Guo Wei, Alex B. Burgin, Todd R. Golub, Brian K. Hubbard, Michael H. Serrano-Wu
A Maltose-Binding Protein Fusion Construct Yields A Robust Crystallography Platform For Mcl1, Matthew C. Clifton, David M. Dranow, Alison Leed, Ben Fulroth, James W. Fairman, Jan Abendroth, Kateri A. Atkins, Ellen Wallace, Dazhong Fan, Guoping Xu, Z. J. Ni, Douglas S. Daniels, John Van Drie, Guo Wei, Alex B. Burgin, Todd R. Golub, Brian K. Hubbard, Michael H. Serrano-Wu
Chemistry Faculty Publications
Crystallization of a maltose-binding protein MCL1 fusion has yielded a robust crystallography platform that generated the first apo MCL1 crystal structure, as well as five ligand-bound structures. The ability to obtain fragment-bound structures advances structure-based drug design efforts that, despite considerable effort, had previously been intractable by crystallography. In the ligand-independent crystal form we identify inhibitor binding modes not observed in earlier crystallographic systems. This MBP-MCL1 construct dramatically improves the structural understanding of well-validated MCL1 ligands, and will likely catalyze the structure-based optimization of high affinity MCL1 inhibitors.
Strong Influence Of Coadsorbate Interaction On Co Desorption Dynamics On Ru(0001) Probed By Ultrafast X-Ray Spectroscopy And Ab Initio Simulations, H. Xin, Jerry L. Larue, H. Öberg, M. Beye, M. Dell'angela, J. J. Turner, J. Gladh, M. L. Ng, J. A. Sellberg, S. Kaya, G. Mercurio, F. Hieke, D. Nordlund, W. F. Schlotter, G. L. Dakovski, M. P. Minitti, A. Föhlisch, M. Wolf, W. Wurth, H. Ogasawara, J. K. Nørskov, H. Öström, L. G. M. Pettersson, A. Nilsson, F. Abild-Pedersen
Strong Influence Of Coadsorbate Interaction On Co Desorption Dynamics On Ru(0001) Probed By Ultrafast X-Ray Spectroscopy And Ab Initio Simulations, H. Xin, Jerry L. Larue, H. Öberg, M. Beye, M. Dell'angela, J. J. Turner, J. Gladh, M. L. Ng, J. A. Sellberg, S. Kaya, G. Mercurio, F. Hieke, D. Nordlund, W. F. Schlotter, G. L. Dakovski, M. P. Minitti, A. Föhlisch, M. Wolf, W. Wurth, H. Ogasawara, J. K. Nørskov, H. Öström, L. G. M. Pettersson, A. Nilsson, F. Abild-Pedersen
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution …
Optical Laser-Induced Co Desorption From Ru(0001) Monitored With A Free-Electron X-Ray Laser: Dft Prediction And X-Ray Confirmation Of A Precursor State, H. Öberg, J. Gladh, M. Dell'angela, T. Anniyev, M. Beye, R. Coffee, A. Föhlisch, T. Katayama, S. Kaya, Jerry L. Larue, A. Møgelhøj, D. Nordlund, H. Ogasawara, W. F. Schlotter, J. A. Sellberg, F. Sorgenfrei, J. J. Turner, M. Wolf, W. Wurth, H. Öström, A. Nilsson, J. K. Nørskov, L. G. M. Pettersson
Optical Laser-Induced Co Desorption From Ru(0001) Monitored With A Free-Electron X-Ray Laser: Dft Prediction And X-Ray Confirmation Of A Precursor State, H. Öberg, J. Gladh, M. Dell'angela, T. Anniyev, M. Beye, R. Coffee, A. Föhlisch, T. Katayama, S. Kaya, Jerry L. Larue, A. Møgelhøj, D. Nordlund, H. Ogasawara, W. F. Schlotter, J. A. Sellberg, F. Sorgenfrei, J. J. Turner, M. Wolf, W. Wurth, H. Öström, A. Nilsson, J. K. Nørskov, L. G. M. Pettersson
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
We present density functional theory modeling of time-resolved optical pump/X-ray spectroscopic probe data of CO desorption from Ru(0001). The BEEF van der Waals functional predicts a weakly bound state as a precursor to desorption. The optical pump leads to a near-instantaneous (< 100 fs) increase of the electronic temperature to nearly 7000 K. The temperature evolution and energy transfer between electrons, substrate phonons and adsorbate is described by the two-temperature model and found to equilibrate on a timescale of a few picoseconds to an elevated local temperature of ~ 2000 K. Estimating the free energy based on the computed potential of mean force along the desorption path, we find an entropic barrier to desorption (and by time-reversal also to adsorption). This entropic barrier separates the chemisorbed and precursor states, and becomes significant at the elevated temperature of the experiment (~ 1.4 eV at 2000 K). Experimental pump-probe X-ray absorption/X-ray emission spectroscopy indicates population of a precursor state to desorption upon laser-excitation of the system (Dell'Angela et al., 2013). Computing spectra along the desorption path confirms the picture of a weakly bound transient state arising from ultrafast heating of the metal substrate.
Temperature Dependent C-Axis Hole Mobilities In Rubrene Single Crystals Determined By Time-Of-Flight, Russell L. Lidberg, Tom J. Pundsack, Neale O. Haugen, Lucas R. Johnstone, C. Daniel Frisbie
Temperature Dependent C-Axis Hole Mobilities In Rubrene Single Crystals Determined By Time-Of-Flight, Russell L. Lidberg, Tom J. Pundsack, Neale O. Haugen, Lucas R. Johnstone, C. Daniel Frisbie
Physics and Astronomy Faculty Publications
Hole mobilities (μ) in rubrene single crystals (space group Cmca) along the crystallographic c-axis have been investigated as a function of temperature and applied electric field by the time-of-fight method. Measurements demonstrate an inverse power law dependence on temperature, namely,μ=μ0T−n with n = 1.8, from room temperature down to 180 K. At 296 K, the average value of μ was found to be 0.29 cm2/Vs increasing to an average value of 0.70 cm2/Vs at 180 K. Below 180 K a decrease in mobility is observed with further cooling. Overall, these results confirm the …