Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, 2019 East Tennessee State University
Development Of Granulated Adsorbent For Clean-Up Of Water Contaminated By Cesium, Esther Alorkpa
Electronic Theses and Dissertations
A study was conducted on sol-gel synthesis of an adsorbent (phosphotungstic acid embedded in silica gel, H-PTA/SiO2) of radioactive cesium. A novelty of this work is covalent bonding of PTA to the surface of solid support that prevents leaching from the surface of the material. The sample was granulated with a binder, aluminium oxide (γ-Al2O3). Solid-state NMR and FT-IR spectroscopy were used to confirm the presence of Keggin units of PTA in the bound materials. Thermal analysis of H-PTA/SiO2 - γ-Al2O3 (50 %) showed that the water content in the bound material ...
Synthesis Of A Hydrophobic/Hydrophilic Nano-Patterned Metal-Organic Framework Material, 2019 Kansas State University Libraries
Synthesis Of A Hydrophobic/Hydrophilic Nano-Patterned Metal-Organic Framework Material, Daniel Pivaral
Kansas State University Undergraduate Research Conference
Metal-Organic Framework (MOF) materials are supramolecular structures that are formed from the assembly of organic molecules that[AL1] have multiple binding sites with compatible metal cations. The resulting structure is a uniform and porous 3D grid-like with metal vertices that are connected by organic linkers. MOFs have several potential uses such as catalysis, detection, and gas storage, and new strategies to synthesize functional MOFs continue to be developed. One strategy is post synthetic modification (PSM), a process where different chemical groups are grafted onto the organic linkers via chemical reaction. The main objective of this research is to demonstrate that ...
Effects Of Disorder On Thermoelectric Properties Of Semiconducting Polymers, 2019 University of Massachusetts - Amherst
Effects Of Disorder On Thermoelectric Properties Of Semiconducting Polymers, Zlatan Aksamija, Dhandapani Venkataraman, Connor J. Boyle, Meenakshi Upadhyaya
Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, 2019 Iowa State University and Ames Laboratory
Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel
To assess the energetics of Cu intercalation on defective graphite, the chemical potentials and binding energies for Cu at graphite step edges are calculated for three main configurations: an isolated atom, a chain, and an atom attached to a chain. As expected, for Cu interacting directly with a graphite step edge, the strength of interaction depends on the stability of the step, with Cu binding more strongly at a less-stable step. However, the relationship is reversed when considering binding of a Cu atom attached to a chain. Taken together, these trends mean that if the graphite step is less stable ...
Role Of Structure And Oxidation States In The Passivation Of Stainless Steel By Chromium, 2019 Louisiana Tech University
Role Of Structure And Oxidation States In The Passivation Of Stainless Steel By Chromium, Suman Bhasker Ranganath, Collin D. Wick, B. R. Ramachandran
B. Ramu Ramachandran
Toward Unraveling The Mechanisms Of “Green” Mechanochemical Reactions, 2019 Old Dominion University
Toward Unraveling The Mechanisms Of “Green” Mechanochemical Reactions, Richard Chen, Mehmet Kerem Gokus
Undergraduate Research Symposium
The mechanical processing of solids, such as milling or grinding powders, often leads to mechanochemical reactions. Mechanochemistry affords “green” synthetic routes avoiding or reducing the use of solvents, thus providing environmentally friendly and cost-effective synthetic alternatives for many materials. The solid-state reactants are usually ground together with small quantities of organic solvents, called “liquid assisted grinding” (LAG). LAG increases the reaction rates, it can yield products from otherwise unreactive mixtures, it increases the products crystallinity, and it selectively leads to crystal structures (polymorphs) of the products, depending on the quantities and physicochemical properties of the liquids used in LAG.
On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, 2019 Iowa State University
On The Role Of Composition And Processing Parameters On The Microstructure Evolution Of Ti-Xmo Alloys, Michael Y. Mendoza, Peyman Samimi, David A. Brice, Iman Ghamarian, Matt Rolchigo, Richard Lesar, Peter Collins
Materials Science and Engineering Publications
Laser Engineered Net Shaping (LENS™) was used to produce a compositionally graded Ti-xMo (0 ≤ x ≤ 12 wt %) specimen and nine Ti-15Mo (fixed composition) specimens at different energy densities to understand the composition–processing–microstructure relationships operating using additive manufacturing. The gradient was used to evaluate the effect of composition on the prior-beta grain size. The specimens deposited using different energy densities were used to assess the processing parameters influence the microstructure evolutions. The gradient specimen did not show beta grain size reduction with the Mo content. The analysis from the perspective of the two grain refinement mechanisms based on a ...
Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, 2019 South Dakota State University
Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, Eleanor Haeska, Megan Radtke
The Journal of Undergraduate Research
Green chemistry seeks to make chemical procedures safer, improve reaction efficiency, and utilize environmentally safe reagents. Deep eutectic solvents (DES) have recently become of great interest due to their eco-friendly nature and functionality as solvent for various chemical processes. One key characteristic of DES is their conductive nature and depressed melting point. This project sought to determine the effect of the addition of aqueous solutions of halides on the conductivity of two selected types of DES. Also assessed were the polarity and viscosity of the DES. It can be concluded that aqueous halides had no measureable effect on the conductivity ...
Oxidative Degradation Of Lignin And Investigation Of Utilization Of Lignin-Derived Materials As Building Blocks For Epoxy Resins, Zhen Fang
Theses and Dissertations--Chemistry
Lignin, the second most abundant biopolymer on earth, is potentially a replaceable source for bulky fuels and chemical feedstocks. There have been numerous reports on methods for the oxidative cleavage of β-O-4 linkages but relatively few reports of how those methods affect other linkages that are present in lignin. We investigated how the β-1 and β-5 linkages respond under oxidative conditions proposed for lignin deconstruction based on their effect on β-O-4 linkages. Mechanochemical treatment of lignin can greatly improve the yield of monomer products and we applied a mechanochemical approach, using powerful ring-and-puck milling to promote lignin degradation. Along with ...
Crystallographically Determined Etching And Its Relevance To The Metal-Assisted Catalytic Etching (Mace) Of Silicon Powders, 2019 West Chester University of Pennsylvania
Crystallographically Determined Etching And Its Relevance To The Metal-Assisted Catalytic Etching (Mace) Of Silicon Powders, Kurt W. Kolasinski, Bret A. Unger, Alexis T. Ernst, Mark Aindow
Chemistry Faculty Publications
Metal-assisted catalytic etching (MACE) using Ag nanoparticles as catalysts and H2O2 as oxidant has been performed on single-crystal Si wafers, single-crystal electronics grade Si powders, and polycrystalline metallurgical grade Si powders. The temperature dependence of the etch kinetics has been measured over the range 5–37◦C. Etching is found to proceed preferentially in a h001i direction with an activation energy of ∼0.4 eV on substrates with (001), (110), and (111) orientations. A quantitative model to explain the preference for etching in the h001i direction is developed and found to be consistent with the measured activation energies. Etching of ...
Atomic-Scale Structure Of Mesoporous Silica-Encapsulated Pt And Ptsn Nanoparticles Revealed By Dynamic Nuclear Polarization-Enhanced Si-29 Mas Nmr Spectroscopy, Evan Wenbo Zhao, Raghu Maligal-Ganesh, Frederic Mentink-Vigier, Tommy Yunpu Zhao, Yong Du, Yuchen Pei, Wenyu Huang, Clifford Russell Bowers
Mesoporous silica encapsulated Pt (Pt@mSiO2) and PtSn (PtSn@mSiO2) nanoparticles (NPs) are representatives of a novel class of heterogeneous catalysts with uniform particle size, enhanced catalytic properties, and superior thermal stability. In the ship-in-a-bottle synthesis, PtSn@mSiO2intermetallic NPs are derived from Pt@mSiO2 seeds where the mSiO2 shell is formed by polymerization of tetraethyl orthosilicate around a tetradecyltrimethylammonium bromide template, a surfactant used to template MCM-41. Incorporation of Sn into the Pt@mSiO2 seeds is accommodated by chemical etching of the mSiO2 shell. The effect of this etching on the atomic-scale structure of the mSiO2 has not been previously ...
Kinetics Of The Γ–Δ Phase Transition In Energetic Nitramine-Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine, 2019 Los Alamos National Laboratory
Kinetics Of The Γ–Δ Phase Transition In Energetic Nitramine-Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine, P. Bowlan, B. F. Henson, L. Smilowitz, Valery I. Levitas, N. Suvorova, D. Oschwald
Aerospace Engineering Publications
The solid, secondary explosive nitramine-octahydro-1,3,5,7-tetranitro-1,3,5,7 or HMX has four different stable polymorphs which have different molecular conformations, crystalline structures, and densities, making structural phase transitions between these nontrivial. Previous studies of the kinetics of the β–δ HMX structural transition found this to happen by a nucleation and growth mechanism, where growth was governed by the heat of fusion, or melting, even though the phase transition temperature is more than 100 K below the melting point. A theory known as virtual melting could easily justify this since the large volume difference in the two ...
Precipitation And Coacervation In Polyelectrolyte-Colloid Systems, 2019 University of Massachusetts Amherst
Precipitation And Coacervation In Polyelectrolyte-Colloid Systems, Fatih Comert
Complex coacervation between oppositely charged polyelectrolytes (PEs) and colloids (i.e. micelles and proteins) has increasingly become popular due to the use of these materials in a range of applications including but not limited to personal care, biomaterials, protein purification, and food science. In taking advantage of complex coacervation, which is a liquid-liquid phase separation, precipitation has always represented a problem by introducing inhomogeneities, irreversibility and irreproducible kinetics. Therefore, understanding the dominant factors driving the formation of precipitates is important to control outcomes.
In this work, we have performed comparative studies of coacervation and precipitation in model PE-colloid systems to ...
Kinetics, Energetics, And Size Dependence Of The Transformation From Pt To Ordered Ptsn Intermetallic Nanoparticles, Minda Chen, Yong Han, Tian Wei Goh, Rong Sun, Raghu V. Maligal‐Ganesh, Yuchen Pei, Chia‐ Kuang Tsung, James W. Evans, Wenyu Huang
The outstanding catalytic activity and chemical selectivity of intermetallic compounds make them excellent candidates for heterogeneous catalysis. However, the kinetics of their formation at the nanoscale is poorly understood or characterized, and precise control of their size, shape as well as composition during synthesis remains challenging. Here, using well-defined Pt nanoparticles (5 nm and 14 nm) encapsulated in mesoporous silica, we study the transformation kinetics from monometallic Pt to intermetallic PtSn at different temperatures by a series of time-evolution X-ray diffraction studies. Observations indicate an initial transformation stage mediated by Pt surface-controlled intermixing kinetics, followed by a second stage with ...
Near Room Temperature Antiferromagnetic Ordering With A Potential Low Dimensional Magnetism In Almn2b2, 2019 Iowa State University and Ames Laboratory
Near Room Temperature Antiferromagnetic Ordering With A Potential Low Dimensional Magnetism In Almn2b2, Tej N. Lamichhane, Khusboo Rana, Qisheng Lin, Sergey L. Bud’Ko, Yuji Furukawa, Paul C. Canfield
We present self flux growth and characterization of single crystalline AlMn2B2. It is an orthorhombic (space group Cmmm), layered material with a plate like morphology. The anisotropic bulk magnetization data, electrical transport and 11B nuclear magnetic resonance(NMR) data revealed an antiferromagnetic (AFM) transition at 313 ± 2 K. In the magnetization data, there is also a broad local maximum significantly above the AFM transition that could be a signature of low dimensional magnetic interactions in AlMn2B2.
Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, 2019 Northeastern University
Squeezed Nanocrystals: Equilibrium Configuration Of Metal Clusters Embedded Beneath The Surface Of A Layered Material, Scott E. Julien, Ann Lii-Rosales, Kai-Tak Wan, Yong Han, Michael C. Tringides, James W. Evans, Patricia A. Thiel
Shapes of functional metallic nanocrystals, typically synthesized either free in solution or supported on surfaces, are key for controlling properties. Here, we consider a novel new class of metallic nanocrystals, copper islands embedded near the surface of graphite, which can be considered a model system for metals embedded beneath surfaces of layered materials, or beneath supported membranes. We develop a continuum elasticity (CE) model for the equilibrium shape of these islands, and compare its predictions with experimental data. The CE model incorporates appropriate surface energy, adhesion energies, and strain energy. The agreement between the CE model and the data is ...
Heterobimetallic Single-Source Precursors: A Springboard To The Synthesis Of Binary Intermetallics, 2019 Iowa State University
Heterobimetallic Single-Source Precursors: A Springboard To The Synthesis Of Binary Intermetallics, Carena L. Daniels, Deyny L. Mendivelso-Perez, Bryan A. Rosales, Di You, Sumit Sahu, J. Stuart Jones, Emily A. Smith, FrançOis P. Gabbaï, Javier Vela
Intermetallics are atomically ordered crystalline compounds containing two or more main group and transition metals. In addition to their rich crystal chemistry, intermetallics display unique properties of interest for a variety of applications, including superconductivity, hydrogen storage, and catalysis. Because of the presence of metals with a wide range of reduction potentials, the controlled synthesis of intermetallics can be difficult. Recently, soft chemical syntheses such as the modified polyol and ship-in-a-bottle methods have helped advance the preparation of these materials. However, phase-segregated products and complex multistep syntheses remain common. Here, we demonstrate the use of heterobimetallic single-source precursors for the ...
Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, 2019 Iowa State University
Rapid Prototyping Of Reconfigurable Microfluidic Channels In Undercooled Metal Particle-Elastomer Composites, Boyce Chang, Mario Fratzl, Andrea Boyer, Andrew Martin, Henry C. Ahrenholtz, Isabelle De Moraes, Jean-Francis Bloch, Nora M. Dempsey, Martin M. Thuo
Materials Science and Engineering Publications
Conventional fabrication of microfluidic channels/devices are faced with challenges such as single use channels and/or significant time consumption. We propose a flexible platform for fabricating microfluidic channels simply through indentation on a smart composite—the so-called ST3R (Stiffness tuning through thermodynamic relaxation) composite. The application of ST3R composite allows rapid fabrication of microfluidic channels by hand or with a prefabricated stamp, and precise prototyping of complex designs using a 2D plotter. Indenter geometry, applied stress, filler loading, and number of repeated indentations affect channel dimensions and/or shape. These channels further exhibit; i) Substantial improvement against swelling by ...
Photo-Isomerizable Complementary Hydrogen Bond Arrays, 2018 The University of Western Ontario
Photo-Isomerizable Complementary Hydrogen Bond Arrays, Jeffrey S. Pleizier
Electronic Thesis and Dissertation Repository
The use of light as an external stimulus provides a non-invasive technique to induce large changes in physical and chemical properties of a substrate. The incorporation of a photochromic subunit into supramolecular polymeric systems therefore adds a potential "smart" quality for polymer manipulation. The azo moiety (-N=N-) is one of the most popular photochromic units as the trans to cis isomerization results in a large degree of spatial rearrangement. This present thesis exploits the azo group by its incorporation into complementary hydrogen bonded complexes. Hydrogen bonding acceptor groups attached to the periphery of the central azo photoswitch provided strong ...
Copper Grafted Titanium Dioxide In Hydrogels For Photocatalysts, 2018 Atlanta University Center
Copper Grafted Titanium Dioxide In Hydrogels For Photocatalysts, Salem Amsaaed
Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University
This study are based on the premise that the incorporation of metal ions into nano titania-PHEMA [poly (2-hydroxyethyl methacrylate)] hydrogels would enhance the desirable properties in the photodecomposition of pollutants. The investigation are centered in the use of Cu(II) as metal ion of interest. The development of TiO2-PHEMA-Cu hydrogels was conducted, and the characterization of the materials by FT-IR, XRD and fluorescence was performed. The absorption of copper(II) from the solution was monitored by UV-Vis. The FT-IR are found too, be the most effective tool too, analyze the interaction of Cu(II) with PHEMA in the ...