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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Elucidating The Pd Active Sites Of Bimetallic Gold-Palladium Catalysts Using Chemisorption And Titration Techniques, Andrew T. Boucher
Elucidating The Pd Active Sites Of Bimetallic Gold-Palladium Catalysts Using Chemisorption And Titration Techniques, Andrew T. Boucher
Electronic Theses and Dissertations
A bimetallic nanoparticle catalyst combines two different metals on an oxide support, which can increase the selectivity towards useful products that may be too tightly bound to a monometallic catalyst. To explore the surface properties of such a system, we made a group of four PdAu bimetallic catalysts with varying gold mass loadings to compare with a parent Pd catalyst. The parent catalyst was synthesized using ion exchange, and gold was added to this parent Pd catalyst using incipient wetness impregnation (IWI) to create four bimetallic catalysts. All catalysts were characterized using H2 and CO chemisorption in tandem with …
Contributions Of Tunneling In 8Π-6Π Electrocyclic Cascade Reactions Of Bicyclo[4.2.0]Octa-2,4-Diene Moieties, Ishika Jain, Claire Castro, William L. Karney
Contributions Of Tunneling In 8Π-6Π Electrocyclic Cascade Reactions Of Bicyclo[4.2.0]Octa-2,4-Diene Moieties, Ishika Jain, Claire Castro, William L. Karney
Featured Student Work
Six-electron electrocyclic reactions usually require relatively high temperatures; however recent research has shown that such reactions can occur at significantly lower temperatures in biosynthetic and biomimetic pathways. Pathways resulting in bicyclo[4.2.0]octa-2,4-diene moieties arise from thermally allowed 8π-6π electrocyclization cascade reactions of 1,3,5,7-octatetraenes, as in the biosynthesis of endiandric acids, elysiapyrones, and numerous other natural products. We report multidimensional tunneling calculations to explore the possible contribution of heavy-atom tunneling (e.g. by carbon) to biosynthetic pathways and biomimetic syntheses, and thus to provide a more complete picture of biochemical kinetics. M06-2X/cc-pVDZ calculations on the 8π-6π cascade cyclizations of methylated octatetraene model systems …
Phosphorus And Its Role In Chemical Evolution, Asbel Gonzalez
Phosphorus And Its Role In Chemical Evolution, Asbel Gonzalez
PANDION: The Osprey Journal of Research and Ideas
Phosphorus is a minor element with a cosmic abundance of about 105.5 atoms per 1012 H atoms (Boudreaux, n.d.). Phosphorus was depleted as a volatile throughout the developing solar system, and as a result, volatile forms of phosphorus would have been minimal, even in the colder regions of the solar nebula. Despite its low abundance, phosphorus minerals play key roles in planetary petrology, including through the formation of phosphate minerals that trapped volatiles and rare Earth elements, and in the formation of metal phosphides that may have served as nucleation sites for kamacite and taenite crystal growth in minor planet …
The Investigation Of Singlet Fission From The Perspective Of Hierarchy Of Pure States (Hops), Tao (James) Chen
The Investigation Of Singlet Fission From The Perspective Of Hierarchy Of Pure States (Hops), Tao (James) Chen
Chemistry Theses and Dissertations
This thesis provides a preliminary investigation of singlet fission from the perspective of Hierarchy of pure states (HOPS), which provides a numerical exact solution for the investigation of a series of open quantum systems. Since the inception of the concept of singlet fission about half a century ago, this photo-physical process has attracted the attention of a multitude of researchers and has been extensively studied theoretically and experimentally. However, these previous methods for the investigation of singlet fission focus more or less on tackling the underlying mechanisms of singlet fission from the perspective of perturbation. So far, the HOPS method …
The Investigation Of Singlet Fission From The Perspective Of Hierarchy Of Pure States (Hops), Tao (James) Chen
The Investigation Of Singlet Fission From The Perspective Of Hierarchy Of Pure States (Hops), Tao (James) Chen
Chemistry Theses and Dissertations
This thesis provides a preliminary investigation of singlet fission from the perspective of Hierarchy of pure states (HOPS), which provides a numerical exact solution for the investigation of a series of open quantum systems. Since the inception of the concept of singlet fission about half a century ago, this photo-physical process has attracted the attention of a multitude of researchers and has been extensively studied theoretically and experimentally. However, these previous methods for the investigation of singlet fission focus more or less on tackling the underlying mechanisms of singlet fission from the perspective of perturbation. So far, the HOPS method …
Physical And Chemical Changes Lesson Plan, Admin Stem For Success
Physical And Chemical Changes Lesson Plan, Admin Stem For Success
STEM for Success Showcase
Lesson plan and video for an activity on the difference between physical and chemical changes.
Modeling Excited State Processes In Molecular Aggregates By Constructing An Adaptive Basis For The Hierarchy Of Pure States, Leonel Varvelo
Modeling Excited State Processes In Molecular Aggregates By Constructing An Adaptive Basis For The Hierarchy Of Pure States, Leonel Varvelo
Chemistry Theses and Dissertations
Simulating excitation energy transfer (EET) in molecular materials is of crucial importance for the development of and understanding of materials such as organic photovoltaics and photosynthetic systems and further development of novel materials. The Hierarchy of Pure States (HOPS) is an exact framework for the time evolution of an open quantum system in which a hierarchy of stochastic wave functions are propagated in time. The adaptive HOPS (adHOPS) method achieves size-invariant scaling with the number of simulated molecules for sufficiently large aggregates by using an adaptive basis that moves with the excitation through the material. To demonstrate the power of …
Novel Technique In Production Of Pb (Ii)- Imprinted Polymers, Ehab Mohammed, Mostafa M. Elsheikh, Adham A. El-Zomrawy, Farag A. Ahmed
Novel Technique In Production Of Pb (Ii)- Imprinted Polymers, Ehab Mohammed, Mostafa M. Elsheikh, Adham A. El-Zomrawy, Farag A. Ahmed
Al-Azhar Bulletin of Science
Ion imprinting techniques were used to produce ion imprinted polymer (IIP) particles for the selective removal of Pb2+ from aqueous environments. As the Templating monomers, acrylic acid, acrylic amine ligand, and Methylene Bisacrylamide crosslinker were chosen. The imprinted polymer was prepared by free radical polymerization. By leaching with 0.1 M HCl, the (Pb2+) ion was removed from the template. The polymer particles were characterized by IR spectroscopy, Thermal analysis and potentiometric analysis. The produced polymer was mechanically crushed into fine particles, assembled into a sensor probe, and linked to a bare HB graphite pencil electrode (GPE). The sensor has a …
Enhanced Adsorption Of Anionic Dyes Using Sr-Doped Zno Nanoparticles: Nonlinear Kinetics And Isotherm Studies, Mostafa H. Mohamed, Taha M. Elmorsi, H. M. Abdelbary
Enhanced Adsorption Of Anionic Dyes Using Sr-Doped Zno Nanoparticles: Nonlinear Kinetics And Isotherm Studies, Mostafa H. Mohamed, Taha M. Elmorsi, H. M. Abdelbary
Al-Azhar Bulletin of Science
Using a co-precipitation process, sr-doped ZnO was prepared and demonstrated to be effective in the removal of anionic congo red dye, since its surface positive charge was increased to 17.3 mV. To investigate the surface morphology and physicochemical characteristics of Sr-doped ZnO, FTIR spectroscopy, scanning electron microscopy (SEM), elemental analysis, and point of zero charges (pHPZC) were employed. We conducted batch adsorption experiments to investigate the effects of contact time (180 minutes), pH (3.5–11), adsorbent dosage (0.5–3.0 g L−1), and temperature (288–328 K). The kinetic study was modeled using several equations, including pseudo-firstorder (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion …