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Husky Hand: A Low-Cost Electro-Mechanical Prosthetic Arm For The Underprivileged, Adam Robert 2021 University of Southern Maine

Husky Hand: A Low-Cost Electro-Mechanical Prosthetic Arm For The Underprivileged, Adam Robert

Thinking Matters Symposium

A continuation of a low-cost prosthetic upper limb prototype design which was investigated in EGN 301. The prosthetic is specifically designed for the needs and requirements of under privileged individuals in the Dominican Republic with upper limb amputations. The project focuses on the creation of an open-source computer aided prosthetic hand/arm model. The design allows consumer-grade fused filament fabrication (FFF) 3-D printers to be used. The improved design allows for the integration of the PQ-12 linear actuator for grasp and finger control. This simplifies the assembly, while, also reducing the size and mass of the whole unit. Producing a ...


Catechol-Containing Copolymers As An Active Ingredient For Denture Adhesives, Vincent Ying Wun Kong 2021 The University of Western Ontario

Catechol-Containing Copolymers As An Active Ingredient For Denture Adhesives, Vincent Ying Wun Kong

Electronic Thesis and Dissertation Repository

Moisture inside the mouth adds challenge to making denture adhesives formulations. Some formulations have zinc to enhance adhesion on wet skin despite knowing the health hazards. Inspired by mussel foot proteins’ catechol unit’s strong underwater adhesion, nine catechol-containing copolymers (P1A-P3C) were synthesized by free radical polymerization of 3,4-dimethoxystyrene (3,4- DMS) with different styrene derivatives followed by deprotection. P1A-P3C were used to make Fn(P)-C-PBS denture adhesive formulations which had suitable shear stresses around ≥ 5 kPa satisfying ISO 10873. In-situ NMR studies of free radical polymerization of 3,4 - DMS and styrene derivatives allowed computation of their ...


High Temperature Polymer Electrolytes For Hydrogen Fuel Cells And Electrochemical Pumps, Gokul Venugopalan 2021 Louisiana State University

High Temperature Polymer Electrolytes For Hydrogen Fuel Cells And Electrochemical Pumps, Gokul Venugopalan

LSU Doctoral Dissertations

Hydrogen fuel cell and separation technologies such as proton exchange membrane fuel cells (PEMFCs) and electrochemical hydrogen pump (ECHP) offer a profound advantage in the transition to a low-carbon economy. An imperative hitch in hydrogen fuel cells and ECHP technology has been the electrocatalyst poisoning by carbon monoxide (CO) and other contaminants in the reactant mixture. By operating, hydrogen fuel cells and ECHPs at high temperatures (>200 °C), the effect of CO adsorption on the electrocatalyst surface could be curtailed. The high-temperature operation of devices necessitates a proton exchange membrane (PEM) to operate under anhydrous conditions.

In this work, a ...


Electrospinning Fibers Via Complex Coacervation, Xiangxi Meng 2021 University of Massachusetts Amherst

Electrospinning Fibers Via Complex Coacervation, Xiangxi Meng

Doctoral Dissertations

Electrospun fibers are high-surface-area materials widely used in applications ranging from batteries to wound dressings. Typically, an electrospinning precursor solution is prepared by dissolving a high-molecular-weight polymer in an organic solvent to form a sufficiently entangled solution. Our approach bypasses the requirement for entanglements and completely avoids toxic chemicals by focusing on using an aqueous complex coacervates solution. Coacervates are a dense, polymer-rich liquid phase resulting from the associative electrostatic complexation of oppositely charged macroions.

We were the first to demonstrate that liquid complex coacervates could be successfully electrospun into polyelectrolyte complex (PEC) fibers. A canonical coacervate system was formed ...


Cfd Simulations Of Stirred-Tank Reactors For Gas-Liquid And Gas-Liquid-Solid Systems Using Openfoam®, Xiaofei Hu, Aziz Dogan Ilgun, Alberto Passalacqua, Rodney O. Fox, Francesco Bertola, Miran Milosevic, Frans Visscher 2021 Iowa State University

Cfd Simulations Of Stirred-Tank Reactors For Gas-Liquid And Gas-Liquid-Solid Systems Using Openfoam®, Xiaofei Hu, Aziz Dogan Ilgun, Alberto Passalacqua, Rodney O. Fox, Francesco Bertola, Miran Milosevic, Frans Visscher

Chemical and Biological Engineering Publications

An open-source CFD software OpenFOAM® is used to simulate two multiphase stirred-tank reactors relevant to industrial processes such as slurry polymerization and fuel production. Gas-liquid simulations are first performed in a single-impeller stirred-tank reactor, studied experimentally by Ford, J. J., T. J. Heindel, T. C. Jensen, and J. B. Drake. 2008. “X-Ray Computed Tomography of a Gas-Sparged Stirred-Tank Reactor.” Chemical Engineering Science 63: 2075–85. Three impeller rotation speeds (200, 350 and 700 rpm) with three different bubble diameters (0.5, 1.5 and 2.5 mm) are investigated. Flow patterns compared qualitatively to those from experiments. Compared to the ...


The Critical Role Of Dynamic Surface Tension Of Surfactants On The Impact Dynamics Of Water Droplets, Amir Esmaeili, Reza Mohammadi 2021 Virginia Commonwealth University

The Critical Role Of Dynamic Surface Tension Of Surfactants On The Impact Dynamics Of Water Droplets, Amir Esmaeili, Reza Mohammadi

Graduate Research Posters

Due to their time-dependent surface tension, the addition of surface-active agents or surfactants to water for specific applications has made controlling the impact dynamics of these droplets a complex phenomenon. This work investigates the influence of the molecular weight, concentration, and ionic nature of the surfactants as well as the substrate surface characteristics on the impact dynamics of surfactant-laden droplets using a high-speed camera at 10000 frames per second. Sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used as anionic, cationic, and nonionic surfactants, respectively. We used hydrophilic glass slides, hydrophobic polytetrafluoroethylene, and superhydrophobic alkyl ketene dimer (AKD) as substrates ...


Assessing Solvent Viscosity Impact On The Physical Characteristics Of Polymeric Organogels, Cameron Hong 2021 Bucknell University

Assessing Solvent Viscosity Impact On The Physical Characteristics Of Polymeric Organogels, Cameron Hong

Honors Theses

Traditionally, studies of polymeric organogels focus on the impact of polymer factors (e.g., molecular weight and polymer concentration) on the gels’ mechanical and transport properties. Alternatively, this study seeks to assess the impact of altering solvent viscosity, while holding polymer factors constant. The gels in this study were composed of different viscosity mineral oils, styrene-ethylene-butylene-styrene (SEBS) triblock copolymer as a gelator, and oleic acid (OA) as a model drug. Samples were formulated to have 6.5, 11.2, and 15.7 wt% SEBS copolymer for each mineral oil, varying in viscosity from ≈30 mPa*s to ≈500 mPa*s ...


Molecular Recognition Of Pet Depolymerization Products And Beta-Cyclodextrin, Thomas Palisin 2021 The University of Akron

Molecular Recognition Of Pet Depolymerization Products And Beta-Cyclodextrin, Thomas Palisin

Williams Honors College, Honors Research Projects

Using molecular recognition techniques to determine the binding constant of the host-guest relationships of the depolymerization products of polyethylene terephthalate (PET) and cyclodextrin species. The main method of data collection used was florescence spectroscopy. Using a titration method and measuring the florescence intensity, a nonlinear regression was used to determine the binding constant.


Wetting Transition On 3d-Printed Featured Surface, Hannah Pineault 2021 The University of Akron

Wetting Transition On 3d-Printed Featured Surface, Hannah Pineault

Williams Honors College, Honors Research Projects

The primary objective of this research project was to gain a better understanding of surface characteristics to produce a long-lasting superhydrophobic or superhydrophilic surface. In other words, when will a droplet of water remain on top of a featured surface and when does the transition occur to water filling the grooves of the surface? This research focused on how to best fabricate porous structures that would stay completely dry at all times by preventing the liquid from penetrating. In particular, we followed the behaviors of water droplets placed on top of 3-D printed featured surfaces with various geometries and surface ...


Investigation Of Surface Charge Using Faraday Bucket Measurements: Analysis On Electrospun Polyvinylidene Fluoride Fiber Mats, Ryan Kantenwein 2021 The University of Akron

Investigation Of Surface Charge Using Faraday Bucket Measurements: Analysis On Electrospun Polyvinylidene Fluoride Fiber Mats, Ryan Kantenwein

Williams Honors College, Honors Research Projects

Piezoelectric polymer materials such as polyvinylidene fluoride exhibit beneficial properties for use in personal protective equipment (PPE) against viral contaminants and other foreign microparticles. The electrospinning process of this material allows for surface charge to develop over a controlled surface area. Kynar 761 at 10 wt% demonstrates increased surface charge after withstanding a flow of aerated NaCl particles from a TSI 8130 instrument. Utilizing voltage measurements from a Faraday bucket, 18 wt% Kynar 761 and MG-15 exhibit surface charge when undergoing an electrospinning process; however, Kynar MG-15 displays lower charge values than that of Kynar 761. Several critical factors such ...


Comparison Of The Effects Of Hofmeister Ions On Transition Temperature Of Two Thermoresponsive Polymers, Ashley Knight 2021 The University of Akron

Comparison Of The Effects Of Hofmeister Ions On Transition Temperature Of Two Thermoresponsive Polymers, Ashley Knight

Williams Honors College, Honors Research Projects

It has been hypothesized that poly(vinylmethylether) (PVME) could be used to replace poly(N-isopropylacrylamide) (pNIPAAM) in various thermoresponsive applications based on literature searches and previous lab experiments. PVME is cheaper and easier to process, and would make pNIPAAM applications more cost effective. In order to verify this, experimental data was gathered on the effects of four anions from the Hofmeister series (SO42-, Cl-, I-, and SCN-) on the lower critical solution temperature (LCST) of pNIPAAM and compared to previous data collected on PVME. Commercial pNIPAAM from Sigma Aldrich and Polysciences were used. The reported LCST range for pNIPAAM ...


Silicon Nanocrystals As Signal Transducers In Ionophore-Based Fluorescent Nanosensors, Mark S. Ferris, Ashley P. Chesney, Bradley J. Ryan, Utkarsh Ramesh, Matthew G. Panthani, Kevin J. Cash 2020 Colorado School of Mines and National Institute of Standards and Technology

Silicon Nanocrystals As Signal Transducers In Ionophore-Based Fluorescent Nanosensors, Mark S. Ferris, Ashley P. Chesney, Bradley J. Ryan, Utkarsh Ramesh, Matthew G. Panthani, Kevin J. Cash

Chemical and Biological Engineering Publications

Colloidal silicon crystallites in the size range of 1-12 nm, also referred to as “silicon nanocrystals” have unique optical properties that include high quantum efficiency, size-dependent emission spanning the visible to near-infrared range, and robust photostability. These features, combined with silicon’s high earth-abundance and good biocompatibility, make them an attractive option to serve as signal transduction elements in bioanalytical sensors. In this study, we combine silicon nanocrystals with a sodium-selective ionophore and a charge balancing additive in polymeric nanosensors to create a Silicon Nanocrystal NanoSensor (SiNC-NS). The SiNC-NS responded to sodium through a decrease in fluorescence intensity without the ...


Noise And Detectivity Limits In Organic Shortwave Infrared Photodiodes With Low Disorder, Zhenghui Wu, Ning Li, Naresh Eedugurala, Jason D. Azoulay, Dong Seok Leem, Tse Nga Ng 2020 The Electrical and Computer Engineering Department

Noise And Detectivity Limits In Organic Shortwave Infrared Photodiodes With Low Disorder, Zhenghui Wu, Ning Li, Naresh Eedugurala, Jason D. Azoulay, Dong Seok Leem, Tse Nga Ng

Faculty Publications

© 2020, The Author(s). To achieve high detectivity in infrared detectors, it is critical to reduce the device noise. However, for non-crystalline semiconductors, an essential framework is missing to understand and predict the effects of disorder on the dark current. This report presents experimental and modeling studies on the noise current in exemplar organic bulk heterojunction photodiodes, with 10 donor–acceptor combinations spanning wavelength between 800 and 1600 nm. A significant reduction of the noise and higher detectivity were found in devices using non-fullerene acceptors (NFAs) in comparison to those using fullerene derivatives. The low noise in NFA blends was ...


Interfacial And Bulk Assembly Of Anisotropic Gold Nanostructures: Implications For Photonics And Plasmonics, Hyeong Jin Kim, Md Mir Hossen, Andrew C. Hillier, David Vaknin, Surya K. Mallapragada, Wenjie Wang 2020 Iowa State University and Ames Laboratory

Interfacial And Bulk Assembly Of Anisotropic Gold Nanostructures: Implications For Photonics And Plasmonics, Hyeong Jin Kim, Md Mir Hossen, Andrew C. Hillier, David Vaknin, Surya K. Mallapragada, Wenjie Wang

Chemical and Biological Engineering Publications

We report on the assembly of polymer-grafted nanostructures at the vapor/aqueous interface and in bulk solutions using synchrotron X-ray diffraction methods. Triangular- and octahedral-shaped gold nanostructures are synthesized and grafted with poly(ethylene glycol) (referred to as PEG-AuNTs and PEG-AuNOh, respectively), and their suspensions are manipulated with salts, (poly)electrolytes that induce interpolymer complexation and HCl to achieve organized assemblies. The assemblies at the vapor/liquid interface are explored by X-ray reflectivity and grazing-incidence small-angle X-ray scattering. Results show that PEG-AuNTs and PEG-AuNOh populate the interface, with some degree of orientation with respect to the liquid surface. The resulting ...


Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu 2020 University of Massachusetts Amherst

Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu

Doctoral Dissertations

This thesis aims to extend the understanding and explore the application of temperature-responsive hydrogel systems by integrating microelectromechanical systems (MEMS). Stimuli-responsive hydrogel systems are immensely investigated and applied in numerous fields, and interfacing with micro- and nano-fabrication techniques will open up more possibilities.

In Chapter 2, the first biologically relevant, in vitro cell stretching device based on hydrogel surface instability was developed. This dynamic platform is constructed by embedding micro-heater devices under temperature-responsive surface-attached hydrogels. The fast and regional temperature change actuates the stretching and relaxation of the seeded human artery smooth muscle cell (HASMC) via controllable surface creasing instability ...


Sequence Control Of Complex Coacervation, Li-Wei Chang 2020 University of Massachusetts Amherst

Sequence Control Of Complex Coacervation, Li-Wei Chang

Doctoral Dissertations

Complex coacervation is a liquid-liquid phase separation driven by the complexation of oppositely charged polyelectrolytes. The resulting coacervate phase has been used for many applications, such as underwater adhesives, drug delivery, food and personal care products. There also has been increasing interest in coacervate-like droplets occurring in biological systems. The majority of these “membraneless organelles” involve a combination of intrinsically-disordered proteins and RNA, and phase separate due to long-range charge effects and short-range hydrophobic effects. While evolution has optimized the self-assembly of these types of biological polymers, our ability to design such materials remains limited, in part because the relevant ...


Kinetics Of The Crystal-Melt Phase Transformation In Semicrystalline Polymers, Kiran Subramaniam Iyer 2020 University of Massachusetts Amherst

Kinetics Of The Crystal-Melt Phase Transformation In Semicrystalline Polymers, Kiran Subramaniam Iyer

Doctoral Dissertations

The assembly of long-chain polymers into an ordered state is a process that has puzzled polymer scientists for several decades. A process that is largely controlled by the strength of intermolecular attractions in small molecular systems, this crystallization in the case of polymers is controlled by a competition between the aforementioned force of attraction between monomers and the formidable conformational entropy of polymer chains. Any factor that affects this conformational entropy, whether that is an equilibrium thermodynamic factor or a kinetic factor, has the ability to control polymer crystallization. In this thesis, we focus on understanding the underlying kinetic processes ...


Synthesis, Self-Assembly And High-Pressure Properties Of Nanoparticles And Hybrid Nanocomposites, Lingyao Meng 2020 University of New Mexico - Main Campus

Synthesis, Self-Assembly And High-Pressure Properties Of Nanoparticles And Hybrid Nanocomposites, Lingyao Meng

Nanoscience and Microsystems ETDs

Nanoparticles have gained significant scientific interests owing to their unique structural dimensions, size- and shape-tunable properties, and numerous fascinating applications, from opto-electronics, sensor devices, to energy, environmental, and medical fields. Furthermore, the synergistic integration of other materials, including organic polymers, with nanoparticles provides new opportunities and strategies to obtain nanocomposites with superior properties and functionalities. While there is already significant research on the synthesis and characterizations of nanoparticles and hybrid nanocomposites, some research questions, such as how to design and control the interfacial morphology in polymer/nanoparticle hybrid nanocomposites, how to synthesize metal- organic framework (MOF) nanoparticles in well-defined and ...


Polystyrene-Block-Polydimethylsiloxane As A Potential Silica Substitute For Polysiloxane Reinforcement, Liyang Shen, Tung-Ping Wang, Fang-Yi Lin, Sabrina Torres, Thomas Robison, Sri Harsha Kalluru, Nacú B. Hernández, Eric W. Cochran 2020 Iowa State University

Polystyrene-Block-Polydimethylsiloxane As A Potential Silica Substitute For Polysiloxane Reinforcement, Liyang Shen, Tung-Ping Wang, Fang-Yi Lin, Sabrina Torres, Thomas Robison, Sri Harsha Kalluru, Nacú B. Hernández, Eric W. Cochran

Chemical and Biological Engineering Publications

Here we report microphase-separated poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) as a reinforcing filler in PDMS thermosets that overcomes the long-standing problem of aging in the processing of silica-reinforced silicone. Surprisingly, PS-b-PDMS reinforced composites display comparable mechanical performance to silica-modified analogs, even though the modulus of PS is much smaller than that of silica and there is no evidence of percolation with respect to the rigid PS domains. We have found that a few unique characteristics contribute to the reinforcing performance of PS-b-PDMS. The strong self-assembly behavior promotes batch-to-batch repeatability by having well-dispersed fillers. The ...


Low-Force Compressive And Tensile Actuation For Elastocaloric Heat Pumps, Agata Czernuszewicz, Lucas Griffith, Julie Slaughter, Vitalij K. Pecharsky 2020 Ames Laboratory

Low-Force Compressive And Tensile Actuation For Elastocaloric Heat Pumps, Agata Czernuszewicz, Lucas Griffith, Julie Slaughter, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

The elastocaloric effect underpins a promising solid-state heat pumping technology that, when adopted for commercial and residential applications, can revolutionize the cooling and heating industry due to low environmental impact and substantial energy savings. Known operational demonstration devices based on the elastocaloric effect suffer from low endurance of materials and, in most experimental systems, from large footprints due to bulky actuators required to provide sufficient forces and displacements. We demonstrate a new approach which has the potential to enable a more effective exploitation of the elastocaloric effect by reducing the forces required for actuation. Thin strips of NiTi were incorporated ...


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