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Design And Self-Assembly Of Responsive Scaffolds For Food And Sensing Applications, Uma Sridhar 2019 University of Massachusetts Amherst

Design And Self-Assembly Of Responsive Scaffolds For Food And Sensing Applications, Uma Sridhar

Doctoral Dissertations

Developing an understanding of how molecules, materials and complex systems contribute to biological functions is important since the interpretation of such mechanisms paves the way to further the development of materials that replicate natural functions or impart the observed properties to synthetic materials. The self-assembly of stimuli-responsive scaffolds based on micelles, liposomes, hydrogels and thin films has been of considerable interest. These systems need to be endowed with certain design features which influence the self-assembly and the responsiveness of the scaffold when subjected to external stimuli which could be physical, chemical or biological in nature. This kind of insight is ...


Amphiphilic Assemblies With Responsive Characteristics At Surfaces And Interfaces, Piyachai Khomein 2019 University of Massachusetts Amherst

Amphiphilic Assemblies With Responsive Characteristics At Surfaces And Interfaces, Piyachai Khomein

Doctoral Dissertations

Amphiphilic self-assembly has gained a lot of interest in both academic and industrial fields. Amphiphiles have a unique ability to self-assemble in water, providing a range of nanosized materials of various morphologies. Many efforts have been dedicated to developing responsive amphiphilic assemblies by introducing responsive characteristics into the amphiphile building blocks. Responsive assemblies have been utilized in many promising applications such as targeted drug delivery systems, smart sensors, and electronic devices. Here, we reported four different types of responsive assemblies created via the incorporation of different responsive groups either at the material’s surface or interface.

To achieve the responsive ...


Process Parameter Development Of Additively Manufactured Af9628 Weapons Steel, Erin M. Hager 2019 Air Force Institute of Technology

Process Parameter Development Of Additively Manufactured Af9628 Weapons Steel, Erin M. Hager

Theses and Dissertations

The manufacture of components in Additive Manufacturing processes is limited by the range of materials available. Qualification of materials for Additive Manufacturing is time intensive, and is often specific to a single type of machine. In this study, an approach to selecting power, speed, and hatch spacing values for a newly powderized material, AF9628 weapons steel, is described that results in highly dense (>99.9%) parts on an MLab 200R Cusing. Initial power and speed values used in a weld track study were selected based on a survey of parameters used on similar materials, with a focus on the energy ...


Mg Assisted Flux Growth And Characterization Of Single Crystalline Sm2co17, Tej Nath Lamichhane, Qisheng Lin, Valentin Taufour, Andriy Palasyuk, Tribhuwan Pandey, David Parker, Sergey L. Bud’ko, Paul C. Canfield 2019 Iowa State University and Ames Laboratory

Mg Assisted Flux Growth And Characterization Of Single Crystalline Sm2co17, Tej Nath Lamichhane, Qisheng Lin, Valentin Taufour, Andriy Palasyuk, Tribhuwan Pandey, David Parker, Sergey L. Bud’Ko, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

This paper presents details of Mg-assisted flux growth of Sm2Co17 single crystals in a Ta crucible well below the melting temperature of binary Sm2Co17. Both the crushed single crystalline powder x-ray diffraction (XRD) and single crystalline XRD data revealed the Th2Zn17 type rhombohedral(R-3m) crystal structure. Ta atom is found to be statistically replacing the Co-Co dumbbell with its position being at the center of the dumbbell. The Curie temperature of our lightly Mg and Ta doped Sm2Co17 sample is determined to be ∼1100 K using method of generalized Bloch law fitting of easy axis spontaneous magnetization data.


A Hydride Route To Ternary Alkali Metal Borides: A Case Study Of Lithium Nickel Borides, Volodymyr Gvozdetskyi, Michael P. Hanrahan, Raquel A. Ribeiro, Tae-Hoon Kim, Lin Zhou, Aaron Rossini, Paul C. Canfield, Julia V. Zaikina 2019 Iowa State University

A Hydride Route To Ternary Alkali Metal Borides: A Case Study Of Lithium Nickel Borides, Volodymyr Gvozdetskyi, Michael P. Hanrahan, Raquel A. Ribeiro, Tae-Hoon Kim, Lin Zhou, Aaron Rossini, Paul C. Canfield, Julia V. Zaikina

Chemistry Publications

Ternary lithium nickel borides LiNi3B1.8 and Li2.8Ni16B8 have been synthesized by using reactive LiH as a precursor. This synthetic route allows for the better mixing of the precursor powders, thus facilitating fast preparation of the alkali metal containing ternary borides. This method is suitable for “fast screening” of multicomponent systems comprised of elements with drastically different reactivities. Crystal structures of the compounds LiNi3B1.8 and Li2.8Ni16B8 were reinvestigated by combination of X‐ray single crystal/synchrotron powder diffraction data, solid state 7Li and 11B NMR, and scanning transmission electron microscopy which allow determination of fine structural details ...


Energetics Of Cu Adsorption And Intercalation At Graphite Step Edges, Yong Han, Ann Lii-Rosales, Michael C. Tringides, James W. Evans, Patricia A. Thiel 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

Chemistry Publications

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 ...


Vi3—A New Layered Ferromagnetic Semiconductor, Tai Kong, Karoline Stolze, Erik I. Timmons, Jing Tao, Danrui Ni, Shu Guo, Zoë Yang, Ruslan Prozorov, Robert J. Cava 2019 Princeton University

Vi3—A New Layered Ferromagnetic Semiconductor, Tai Kong, Karoline Stolze, Erik I. Timmons, Jing Tao, Danrui Ni, Shu Guo, Zoë Yang, Ruslan Prozorov, Robert J. Cava

Ames Laboratory Accepted Manuscripts

2D materials are promising candidates for next-generation electronic devices. In this regime, insulating 2D ferromagnets, which remain rare, are of special importance due to their potential for enabling new device architectures. Here the discovery of ferromagnetism is reported in a layered van der Waals semiconductor, VI3, which is based on honeycomb vanadium layers separated by an iodine-iodine van der Waals gap. It has a BiI3-type structure (R (3) over bar, No.148) at room temperature, and the experimental evidence suggests that it may undergo a subtle structural phase transition at 78 K. VI3 becomes ferromagnetic at 49 K, below which ...


Lead‐Free Semiconductors: Soft Chemistry, Dimensionality Control, And Manganese‐Doping Of Germanium Halide Perovskites, Long Men, Bryan A. Rosales, Noreen E. Gentry, Sarah D. Cady, Javier Vela 2019 Iowa State University and Ames Laboratory

Lead‐Free Semiconductors: Soft Chemistry, Dimensionality Control, And Manganese‐Doping Of Germanium Halide Perovskites, Long Men, Bryan A. Rosales, Noreen E. Gentry, Sarah D. Cady, Javier Vela

Chemistry Publications

Lead halide perovskites have drawn enormous interest due to their exceptional photovoltaic and optoelectronic properties. However, the toxic heavy metal lead is harmful to humans and the environment resulting in a need for strategies to replace this toxic element. Herein, we report a facile aqueous synthesis of CsGeX3 (X = I, Br) perovskite nanocrystals with size control achieved by varying the cysteammonium halide ligand concentration. We observe a variety of morphologies including pyramidal, hexagonal, and spheroidal. CsGeX3 nanocrystals undergo a lattice expansion due to partial replacement of Cs+ with larger cysteNH3+ cations into the lattice. We successfully dope Mn2+ into the ...


Self-Assembled Bismuth Selenide (Bi2se3) Quantum Dots Grown By Molecular Beam Epitaxy, Marcel S. Claro, Ido Levy, Abhinandan Gangopadhyay, David J. Smith, Maria C. Tamargo 2019 CUNY City College

Self-Assembled Bismuth Selenide (Bi2se3) Quantum Dots Grown By Molecular Beam Epitaxy, Marcel S. Claro, Ido Levy, Abhinandan Gangopadhyay, David J. Smith, Maria C. Tamargo

Publications and Research

We report the growth of self-assembled Bi2se3 quantum dots (QDs) by molecular beam epitaxy on GaAs substrates using the droplet epitaxy technique. The QD formation occurs after anneal of Bismuth droplets under Selenium flux. Characterization by atomic force microscopy, scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy and X-ray reflectance spectroscopy is presented. Raman spectra confirm the QD quality. The quantum dots are crystalline, with hexagonal shape, and have average dimensions of 12-nm height (12 quintuple layers) and 46-nm width, and a density of 8.5 × 109 cm−2. this droplet growth technique provides a means to produce topological ...


Effects Of High Magnetic Fields On Phase Transformations In Amorphous Nd2fe14b, Michael S. Kesler, Brandt A. Jensen, Lin Zhou, Olena Palasyuk, Tae-Hoon Kim, Matthew J. Kramer, Ikenna C. Nlebedim, Orlando Rios, Michael A. McGuire 2019 Oak Ridge National Laboratory

Effects Of High Magnetic Fields On Phase Transformations In Amorphous Nd2fe14b, Michael S. Kesler, Brandt A. Jensen, Lin Zhou, Olena Palasyuk, Tae-Hoon Kim, Matthew J. Kramer, Ikenna C. Nlebedim, Orlando Rios, Michael A. Mcguire

Ames Laboratory Accepted Manuscripts

We briefly summarize the results from a set of experiments designed to demonstrate the effects of high magnetic fields applied during thermal annealing of amorphous Nd2Fe14B produced through melt-spinning. A custom-built differential scanning calorimeter was used to determine the crystallization temperatures in zero-field and in applied fields of 20 kOe and 90 kOe, which guided subsequent heat treatments to evaluate phase evolution. X-ray diffraction was used for phase identification and transmission electron microscopy was employed for observation of the crystallite size and morphology. Magnetization measurements were also used to evaluate the resulting magnetic phases after thermomagnetic ...


Co Displacement In An Oxidative Addition Of Primary Silanes To Rhodium(I), Abhranil Biswas, Arkady Ellern, Aaron D. Sadow 2019 Iowa State University and Ames Laboratory

Co Displacement In An Oxidative Addition Of Primary Silanes To Rhodium(I), Abhranil Biswas, Arkady Ellern, Aaron D. Sadow

Ames Laboratory Accepted Manuscripts

The rhodium dicarbonyl {PhB(Ox(Me2))(2)Im(Mes)}Rh(CO)(2), (1) and primary silanes react by oxidative addition of a nonpolar Si-H bond and, uniquely, a thermal dissociation of CO. These reactions are reversible, and kinetic measurements model the approach to equilibrium. Thus, 1 and RSiH3 react by oxidative addition at room temperature in the dark, even in CO-saturated solutions. The oxidative addition reaction is first-order in both 1 and RSiH3, with rate constants for oxidative addition of PhSiH3 and PhSiD3 revealing k(H)/k(D) similar to 1. The reverse reaction, reductive elimination of Si-H from {PhB ...


Mechanochemical Reactions And Hydrogen Storage Capacities In Mbh4–Sis2 Systems (M=Li Or Na), Oleksandr Dolotko, Shalabh Gupta, Takeshi Kobayashi, Eric McDonald, Ihor Hlova, Eric Majzoub, Viktor P. Balema, Marek Pruski, Vitalij K. Pecharsky 2019 Ames Laboratory

Mechanochemical Reactions And Hydrogen Storage Capacities In Mbh4–Sis2 Systems (M=Li Or Na), Oleksandr Dolotko, Shalabh Gupta, Takeshi Kobayashi, Eric Mcdonald, Ihor Hlova, Eric Majzoub, Viktor P. Balema, Marek Pruski, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

The hydrogen storage properties, and phase compositions of mechanochemically prepared mixtures of xMBH4-SiS2 (x = 2–8), where M = Li or Na, were investigated using gas sorption analysis, powder X-ray diffraction, and infrared and solid-state NMR spectroscopic methods. The 2LiBH4:1SiS2 system forms an amorphous product that releases ca. 4.3 wt % of H2 below 385 °C with a Tonset of 88 °C without detectable diborane emission. The dehydrogenated sample reversibly absorbs 1.5 wt % of H2 at 385 °C under 160 bar pressure. The H2 release from materials with varying LiBH4:SiS2 ratios peaks at 8.2 wt % for the ...


Development Of In Situ Forming Hydrogels For Intra-Articular Drug Delivery, Andy Prince 2019 The University of Western Ontario

Development Of In Situ Forming Hydrogels For Intra-Articular Drug Delivery, Andy Prince

Electronic Thesis and Dissertation Repository

Hydrogels are 3-dimensional crosslinked polymer networks that can absorb significant amounts of water. The physical properties associated with hydrogels affords them resemblance to biological tissues making them good candidates for biomedical applications. Many pharmaceuticals, specifically non-steroidal anti-inflammatory drugs (NSAIDs), have poor aqueous solubility, which limits their bioavailability and efficacy. People suffering from chronic osteoarthritis (OA) are required to frequently take large doses to mitigate pain, which can lead to serious side effects. Hydrogels are good strategies to deliver NSAIDs via articular injection because they can form solid gels in situ. This thesis describes the synthesis, formulation, mechanical testing, in vitro ...


Toward Unraveling The Mechanisms Of “Green” Mechanochemical Reactions, Richard Chen, Mehmet Kerem Gokus 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.

Mechanochemistry ...


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 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 ...


Microstructure And Magnetic Properties Of Grain Refined Pr2co14b Melt-Spun Ribbons, I. C. Nlebedim, M. Huang, K. Sun, Lin Zhou, R. W. McCallum 2019 Ames Laboratory

Microstructure And Magnetic Properties Of Grain Refined Pr2co14b Melt-Spun Ribbons, I. C. Nlebedim, M. Huang, K. Sun, Lin Zhou, R. W. Mccallum

Ames Laboratory Accepted Manuscripts

The correlation between the grain refining effect of TiC on the microstructure of Pr2Co14B melt-spun ribbons and the magnetic properties is presented in this study. TiC enabled greater control of microstructure both in the as-spun and heat treated Pr2Co14B, compared with the material without TiC. As a result, coercivity of the sample with TiC was nearly twice that of the sample without TiC. In addition to Pr2Co14B, two other phases were found in the sample with TiC: one rich in Co and the other having a composition near ...


Optimization Of Magnetic Powdered Activated Carbon For Aqueous Hg(Ii) Removal And Magnetic Recovery, Emily K. Faulconer, Natalia Hoogesteijn von Reitzenstein, David W. Mazyck 2019 University of Florida

Optimization Of Magnetic Powdered Activated Carbon For Aqueous Hg(Ii) Removal And Magnetic Recovery, Emily K. Faulconer, Natalia Hoogesteijn Von Reitzenstein, David W. Mazyck

Emily Faulconer

Activated carbon is known to adsorb aqueous Hg(II). MPAC (magnetic powdered activated carbon) has the potential to remove aqueous Hg to less than 0.2 mg/L while being magnetically recoverable. Magnetic recapture allows simple sorbent separation from the waste stream while an isolated waste potentially allows for mercury recycling. MPAC Hg-removal performance is verified by mercury mass balance, calculated by quantifying adsorbed, volatilized, and residual aqueous mercury. The batch reactor contained a sealed mercury-carbon contact chamber with mixing and constant N2(g) headspace flow to an oxidizingtrap. Mercury adsorption was performed using spiked ultrapure water (100 mg ...


Effect Of Dissolved Salts On The Physiochemical Properties Of Deep Eutectic Solvents, Eleanor Haeska, Megan Radtke 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 ...


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 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 ...


Reaction Mechanism Between Small-Sized Ce Clusters And Water Molecules: An Ab Initio Investigation On CeN+H2O, Rulong Zhou, Yang Yang, Seema Pande, Bingyan Qu, Dongdong Li, Xiao Cheng Zeng 2019 Hefei University of Technology

Reaction Mechanism Between Small-Sized Ce Clusters And Water Molecules: An Ab Initio Investigation On CeN+H2O, Rulong Zhou, Yang Yang, Seema Pande, Bingyan Qu, Dongdong Li, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Reactions of small-sized cerium clusters Cen (n = 1–3) with a single water molecule are systematically investigated theoretically. The ground state structures of the Cen/H2O complex and the reaction pathways between Cen + H2O are predicted. Our results show the size-dependent reactivity of small-sized Ce clusters. The calculated reaction energies and reaction barriers indicate that the reactivity between Cen and water becomes higher with increasing cluster size. The predicted reaction pathways show that the single Ce atom and the Ce2 and Ce3 clusters can all easily react with H2 ...


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