Materials Science and Engineering Commons^™

Soft-Microrobotics: The Manipulation Of Alginate Artificial Cells, Samuel Sheckman

Mechanical Engineering Research Theses and Dissertations

In this work, the approach to the manipulation of alginate artificial cell soft-microrobots, both individually and in swarms is shown. Fabrication of these artificial cells were completed through centrifugation, producing large volumes of artificial cells, encapsulated with superparamagnetic iron oxide nanoparticles; these artificial cells can be then externally stimulated by an applied magnetic field. The construction of a Permeant Magnet Stage (PMS) was produced to manipulate the artificial cells individually and in swarms. The stage functionalizes the permanent magnet in the 2D xy-plane. Once the PMS was completed, Parallel self-assembly (Object Particle Computation) using swarms of artificial cells in complex …

Investigation Of The Effects Of Harmful Radiation On Type-Ii Strained Layer Superlattice Focal Plane Arrays Operated In The Long Wave Infrared, Patrick Fumo

Electrical Engineering Theses and Dissertations

In-situ exposure of InAs/InAsSb strained layer superlattice focal plane arrays to gamma-rays revealed the possibility of a detector capable of imaging through a total ionizing dose event. Two long wave infrared focal plane arrays were exposed to a Co⁶⁰ source at dose rates of 60 Rads/s and 70 Rads/s in incremental steps up to a total accumulated dose of 30 kRads. The first device showed no degradation in dark current density with accumulated dose while the second device tested showed a small increase up to 1 kRad and minimal increases with subsequent dose steps. The primary imaging defect in …

Ii-Vi Semiconductor Nanowire Array Sensors Based On Piezotronic, Piezo-Phototronic And Piezo-Photo-Magnetotronic Effects, Shuke Yan

LSU New Orleans Theses and Dissertations

With the rapid progress of nanotechnologies, there are two developing trends for the next generation of sensors: miniaturization and multi-functionality. Device miniaturization requires less power consumption, or even self-powered system. Multi-functional devices are usually based on multi-property coupling effects. Piezoelectric semiconductors have been considered to be potential candidates for self-powered/multi-functional devices due to their piezotronic coupling effect. In this dissertation, ZnO and CdSe nanowire arrays have been synthesized as the piezoelectric semiconductor materials to develop the following self-powered/multi-functional sensors: (1) self-powered gas sensors of ZnO/SnO₂, ZnO/In₂O₃, ZnO/WO₃ and CdSe nanowire arrays have been …

Voltage-Controlled Deposition Of Nanoparticles For Next Generation Electronic Materials, Subhodip Maulik

LSU Doctoral Dissertations

This work presents both a feasibility study and an investigation into the voltage-controlled spray deposition of different nanoparticles, namely, carbon nanotubes (CNTs), as well as molybdenum disulfide (MoS₂) and tungsten disulfide (WS₂) from the transition metal dichalcogenides (TMDCs) family of materials. The study considers five different types of substrates as per their potential application to next-generation device electronics. The substrates selected for this research were: 1) aluminum as a conducting substrate, 2) silicon as a semiconducting substrate, 3) glass, silicon dioxide (SiO₂), and syndiotactic poly methyl methacrylate (syndiotactic PMMA) as insulating substrates.

Since the …

Ozone Removal Efficiency And Surface Analysis Of Green And White Roof Hvac Filters, Omed A. Abbass, David Sailor, Elliott T. Gall

Mechanical and Materials Engineering Faculty Publications and Presentations

Heating, ventilation, and air-conditioning ( HVAC ) system filters from a commercial building were tested for their ability to remove ozone from intake air. Filters were taken from rooftop HVAC systems installed for two months: one located on a white membrane roof and the other on a vegetated green roof. One new, unused filter sample was tested as a reference. Samples from these filters were exposed to ozonated air streams at 40 and 120 ppb and relative humidity levels of 30% and 70%. Filter surfaces were analyzed with a scanning electron microscope to observe the structure and composition of the …

Preliminary Investigation Of Tensile Strength And Impact Characterization Of Cementitious Composite Incorporating Carbon Nanotubes, Robabeh Jazaei

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cement has been largely used in the construction industry, specifically as a matrix for concrete. Recently, a new generation of cement-based composite that greatly increases mechanical properties is replacing conventional concrete. With periodic advances in the field, researchers considered particles with high-aspect ratios such as Carbon Nanotubes (CNTs) to reinforce cement matrices. Although there is not much literature to draw upon in research, some research on improving the tensile strength of cementitious composite incorporating with CNTs does exist. However, there had been no evidence of investigation into impact strength until this study.

Most papers presented examined the effect of multi-walled …

Morphological And Energy Transport Optimization Of Spectrally-Selective Solar Absorber Coatings At Mesoscale, Dale Karas

UNLV Theses, Dissertations, Professional Papers, and Capstones

A special class of cuprous-based inorganic oxide materials, synthesized as nanoparticles via hydrothermal and co-precipitation methods, are portable to spectrally-selective absorber coatings with high solar-thermal energy conversion efficiency. Operating reliably at elevated temperatures when used in tandem with solar concentrators, these materials enable cost-competitive solar energy conversion technology that can be incorporated with thermal energy storage systems, supporting the viability of novel renewable power generation; notably, optimizing absorptive performance while mitigating thermal losses through re-radiated waste heat motivates sustainable energy production particular to desert climates, where water conservation and ecological sensitivity needs are paramount.

This work targets the chemical synthesis …

Numerical Study Of Oxidation In Stainless Steel Alloy Ep-823 By Liquid Lead-Bismuth Eutectic, Rajyalakshmi Palaparty

UNLV Theses, Dissertations, Professional Papers, and Capstones

The oxidation of stainless steel is influenced by the presence of oxygen in the surrounding medium; the oxygen reacts with the alloy to form an oxide. In certain environments, such as nuclear reactor coolant systems, minimal oxidation of the stainless steel containment functions as a protective shield from corrosive coolants such as liquid lead-bismuth eutectic.

In the current study, this minimal oxidation is evaluated for a system in which corrosion-resistant stainless steel alloy EP-823 is subject to an environment of flowing oxygenated liquid lead-bismuth eutectic at a temperature of 743 K, whereby the thickness of the forming oxide layer is …

A Novel Approach To Analyzing Strain Heterogeneity In Polycrystalline Quartz Specimens Deformed At High Pressure And Temperature, Nolan Ambrose Regis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Rheological studies of rocks and minerals allow researchers to study the grain-scale deformation mechanisms that govern large-scale geologic processes from mountain building to mantle mixing. Deforming rock samples with high pressure and temperature apparatuses similar to the Griggs piston cylinder apparatus allows us to simulate deformation at depth. However, many apparatuses are limited to “cook-and-look” analysis and require modeling techniques to determine the evolution of deformation patterns found in experimental samples. A previous study used two-dimensional finite element models to analyze the development of stress and strain patterns in polycrystalline rocks. The study suggested rhythmic patterns in deformed rocks develop …

Design And Synthesis Of Novel Nanometallic Catalysts And Electrode Materials For Green Fuel Cells, Jing Zhang

Graduate Dissertations and Theses

The United Nations formally adopted 17 sustainable development goals (SDGs) at its 2015 summit. Many of these goals addressed issues such poverty, hunger, health, education, climate-change, gender equality, water, sanitation, energy, urbanization, environment and social justice. The seventh SDG seeks to ensure access to affordable, reliable, sustainable and modern energy for all. So among all renewable forms of energy, fuel cells with high efficiency have attracted a lot of attention recently. In particular, the direct ethanol fuel cells (DEFCs) and microbial fuel cells (MFCs) are significant due to their green fuel, less waste generated and environmental friendliness. Hence the overall …

Effect Of Zr Additions On Thermal Stability Of Al-Cu Precipitates In As-Cast And Cold Worked Samples, Kyle Deane, Paul G. Sanders

Michigan Tech Publications, Part 1

While Zr is frequently added to Al alloys to control grain size with the formation of large (>1 μm) primary precipitates, little research has been conducted on the effect of nanoscale Al₃Zr precipitates on Al alloys. By comparing the precipitation and corresponding strength evolution between Al-Cu-Zr alloys with different Zr concentrations, the effects of Zr on Al-Cu precipitation with and without primary Al₃Zr precipitates can be observed. In the absence of these large precipitates, all Al₃Zr phases can be formed, through high temperature aging treatments, as a dispersion of nanoprecipaites inside the Al …

Aligned Carbon Nanotube Arrays Bonded To Solid Graphite Substrates: Thermal Analysis For Future Device Cooling Applications, Betty T. Quinton, Levi Elston, James D. Scofield, Sharmila M. Mukhopadhyay

Mechanical and Materials Engineering Faculty Publications

Carbon nanotubes (CNTs) are known for high thermal conductivity and have potential use as nano-radiators or heat exchangers. This paper focuses on the thermal performance of carpet-like arrays of vertically aligned CNTs on solid graphite substrates with the idea of investigating their behavior as a function of carpet dimensions and predicting their performance as thermal interface material (TIM) for electronic device cooling. Vertically aligned CNTs were grown on highly oriented pyrolytic graphite (HOPG) substrate, which creates a robust and durable all-carbon hierarchical structure. The multi-layer thermal analysis approach using Netzsch laser flash analysis system was used to evaluate their performance …

Investigation Of The Use Of A Bio-Derived Solvent For Non-Solvent-Induced Phase Separation (Nips) Fabrication Of Polysulfone Membranes, Xiaobo Dong, Amna Al-Jumaily, Isabel Escobar

Chemical and Materials Engineering Faculty Publications

Organic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc), have been traditionally used to fabricate polymeric membranes. These solvents may have a negative impact on the environment and human health; therefore, using renewable solvents derived from biomass is of great interest to make membrane fabrication sustainable. Methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (Rhodiasolv PolarClean) is a bio-derived, biodegradable, nonflammable and nonvolatile solvent. Polysulfone is a commonly used polymer to fabricate membranes due to its thermal stability, strong mechanical strength and good chemical resistance. From cloud point curves, PolarClean showed potential to be a solvent for polysulfone. Membranes prepared with PolarClean were investigated in terms of …

Research And Development Of Powder Brazing Filler Metals For Diamond Tools: A Review, Fei Long, Peng He, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

Powder brazing filler metals (PBFMs) feature a number of comparative advantages. Among others, these include a low energy consumption, an accurate dosage, a good brazeability, a short production time, and a high production efficiency. These filler metals have been used in the aerospace, automobile, and electric appliances industries. The PBFMs are especially suitable for diamond tools bonding, which involves complex workpiece shapes and requires accurate dosage. The recent research of PBFMs for diamond tools is reviewed in this paper. The current applications are discussed. The CuSnTi and Ni-Cr-based PBFMs have been the two commonly used monolayer PBFMs. Thus, the bonding …

Analysis Of Surface Integrity In Machining Of Aisi 304 Stainless Steel Under Various Cooling And Cutting Conditions, F. Klocke, B. Döbbeler, S. Lung, S. Seelbach, Ibrahim S. Jawahir

Institute for Sustainable Manufacturing Faculty Publications

Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers …

Reprapable Recyclebot: Open Source 3-D Printable Extruder For Converting Plastic To 3-D Printing Filament, Aubrey Woern, Joseph Mccaslin, Adam Pringle, Joshua M. Pearce

Department of Materials Science and Engineering Publications

In order to assist researchers explore the full potential of distributed recycling of post-consumer polymer waste, this article describes a recyclebot, which is a waste plastic extruder capable of making commercial quality 3-D printing filament. The device design takes advantage of both the open source hardware methodology and the paradigm developed by the open source self-replicating rapid prototyper (RepRap) 3-D printer community. Specifically, this paper describes the design, fabrication and operation of a RepRapable Recyclebot, which refers to the Recyclebot’s ability to provide the filament needed to largely replicate the parts for the Recyclebot on any type of RepRap 3-D …

Effects Of Tension On Resonant Frequencies Of Strings, Blake Burnett

Senior Theses

This project tests and explores resonance of strings. Since all materials and mechanisms are affected by vibrations, it is important to know the frequencies at which resonance occurs. To explore this subject, strings were used as a model material to test the effect tension has on resonance. The fundamental frequencies and the corresponding modes of resonance were used to analyze the data. The results of this experiment show that increasing tension on a string increases its resonance frequency. Understanding the physics behind resonance frequency allows systems to be designed to take advantage of resonance properties, or to avoid resonance where …

Measuring The Double Layer Capacitance Of Electrolyte Solutions Using A Graphene Field Effect Transistor, Agatha Ulibarri

Senior Theses

When operating graphene field effect transistors (GFETs) in fluid, a double layer capacitance (C_dl) is formed at the surface. In the literature, the C_dl is estimated using values obtained using metal electrode experiments. Due to the distinctive electronic and surface properties of graphene, there is reason to believe these estimates are inadequate. This work seeks to directly characterize the double layer capacitance of a GFET. A unique method for determining the C_dl has been implemented, and data has been obtained for three electrolytes and one ionic fluid. The results yield dramatically lower C_dl values than …

Real-Time Object Detection And Tracking On Drones, Tu Le

Undergraduate Research & Mentoring Program

Unmanned aerial vehicles, also known as drones, have been more and more widely used in recent decades because of their mobility. They appear in many applications such as farming, search and rescue, entertainment, military, and so on. Such high demands for drones lead to the need of developments in drone technologies. Next generations of commercial and military drones are expected to be aware of surrounding objects while flying autonomously in different terrains and conditions. One of the biggest challenges to drone automation is the ability to detect and track objects of interest in real-time. While there are many robust machine …

Mesoscale Computational Studies Of Thin-Film Bijels, Joseph M. Carmack

Graduate Theses and Dissertations

Bijels are a relatively new class of soft materials that have many potential applications in the technology areas of energy, medicine, and environmental sustainability. They are formed by the arrest of binary liquid spinodal decomposition by a dispersion of solid colloidal nanoparticles. This dissertation presents an in-depth simulation study of Bijels constrained to thin-film geometries and in the presence of electric fields. We validate the computational model by comparing simulation results with previous computational modeling and experimental research. In the absence of suspended particles, we demonstrate that the model accurately captures the rich kinetics associated with diffusion-based surface-directed spinodal decomposition. …

Effects Of Surface-Directed Spinodal Decomposition On Binary Thin-Film Morphology, Michael Brian Wise

Graduate Theses and Dissertations

Preferential wetting can have a significant impact on the kinetics of phase separation in certain systems. The depletion of the wetting component can simply alter domain growth rates or change the structure entirely. In this thesis, we employ a Cahn-Hilliard model to study the evolution of binary thin-films with symmetric surface wetting. Three possible morphologies were identified: discrete, bicontinuous, and a novel quasi-2D bicontinuous structure in which both phases retain continuity throughout the volume as well as on the center xy plane. Using a continuity factor, regions of film thickness versus blend composition were classified as producing a certain morphology. …

Thermoelectrics And Thermoelectric Devices, Benjamin T. Erck

Senior Theses

The field of thermoelectrics has many applications, and more are found in everyday systems. From its current studies, it is apparent that improving the figure of merit zT (which defines a good thermoelectric material) is important in the effectiveness of power generation. Another important part of thermoelectrics is the duality of these devices. They can both move heat and generate power, depending on their role in the system. In this thesis research, a process was made to test these thermoelectric relationships for a few Peltier devices in order to understand their efficiencies and what systems they can be applied to.

Fabrication Of Solid Polymeric 3d Shapes From Programmable Flat Hydrogel Sheets, Ninad Vilas Khadse

Material Science and Engineering Theses - Archive

Modern methods of fabricating three-dimensional (3D) objects include sheet metal forming, thermoforming, and additive manufacturing among others. These methods have their own advantages and disadvantages regarding scalability, customizability, and time efficiency. A promising approach is to program the growth (expansion and contraction) of hydrogel sheets to form 3D structures. The differential growth-induced 3D shaping approach has the advantages of traditional manufacturing (scalability) and additive manufacturing (customizability). The objective of this study is to create nanocomposite 3D structures that are stable in ambient environment using the growth-induced 3D shaping approach. This study determines the effect of silica nanoparticles in hydrogels on …

Characterization Of Normal And Abnormal Bones By Raman Spectroscopy : Analysis Of Mineral To Matrix Ratio Of Bone Using Advanced Materials Characterization Techniques, Meet Yagnesh Shah

Material Science and Engineering Theses - Archive

Bone disorders and disease are associated with multiple factors. Some of the disorders and diseases are difficult to understand because of their unknown root causes. Our goal was to differentiate between normal and genetically modified rat bone groups by finding the difference in mineral to matrix (Mn/Mx) content using Raman spectroscopy. Raman spectroscopy gives the chemical composition based on the vibration modes of the molecules. Quantitative analysis of Mn/Mx content calculated from Raman spectra allowed us to distinguish between healthy and genetically modified rat bone groups. We have presented the results by averaging the Mn/Mx ratios. Thus, the most significant …

Quantitative Analysis Of Mineral/Matrix To Evaluate Genetically Altered Bone With Infrared Spectroscopy And X-Ray Spectral Imaging, Sunil Balasaheb Yadav

Material Science and Engineering Theses - Archive

This thesis focuses on the characterization of bone with the help of Fourier Transform Infrared Spectroscopy and Energy Dispersive Spectroscopy. Such analysis of the physics and chemistry of biomaterials is vital to resolve problems in life science of bone-related diseases and disorders. Material characterization can help in the understanding of disease mechanisms and lead to useful drugs and other treatments. In this thesis, I have used bone materials produced by groundbreaking research at UT Southwestern Research Center and Texas Scottish Rite Children's Hospital to establish that idiopathic clubfoot (Talipes equinovarus) is associated with the Follistatin 5 gene. We studied healthy …

Study Of Copper-Rich Intermetallic Phase Formation In Copper-Aluminum Binary System, Valery Georges Ouvarov-Bancalero

Material Science and Engineering Dissertations - Archive

This work aims to study the initial formation and subsequent growth of intermetallic compounds (IMC) in the binary Al-Cu system. Al-Cu pair configurations have been successfully used for several decades as structural components, and extensive research on their mechanical and metallurgical properties is available. More recently, the microelectronics industry started implementing the Cu wire-bond technology, which renewed the interest of the scientific community. As with every technological evolution, initial quality and reliability issues arose. Copper (Cu) wire to aluminum (Al) bond-pad is prone to crack nucleation leading to failure at the interface between Cu and Cu-rich IMCs. Even though numerous …

Accelerated Creative Problem Solving And Product Improvement Applied To Experimental Devices In A Bloodstain Pattern Interpretation Class--Improving The Role Of Insight Development Tools As A Generator Of New Ideas In Novel Situations, Douglas Ridolfi

Creativity and Change Leadership Graduate Student Master's Projects

This project uses an action research centered study protocol to examine the effects of a problem-based learning exercise related to bloodstain pattern interpretation in a crime scene processing and general criminalistics class taught as part of an upper division forensic chemistry major in a four year college. The goal is to apply design principles and creative problem solving methods directly adapted to a project involving interpreting a set of crime scene photographs depicting blood spatter and with the aid of guided exercises in ideation and design, lead students into the development of alternate theories of how the bloodstains were created …

Elucidating The Effect Of Water-To-Cement Ratio On The Hydration Mechanisms Of Cement, Aida Margarita Ley-Hernandez, Jonathan Lapeyre, Rachel Cook, Aditya Kumar, Dimitri Feys

Materials Science and Engineering Faculty Research & Creative Works

The hydration of cement is often modeled as a phase boundary nucleation and growth (pBNG) process. Classical pBNG models, based on the use of isotropic and constant growth rate of the main hydrate, that is, calcium-silicate-hydrate (C-S-H), are unable to explain the lack of any significant effect of the water-to-cement (w/c) ratio on the hydration kinetics of cement. This paper presents a modified form of the pBNG model, in which the anisotropic growth of C-S-H is allowed to vary in relation to the nonlinear evolution of its supersaturation in solution. Results show that once the supercritical C-S-H nuclei form, their …

Corrosion Resistance Of Pipeline Steel With Damaged Enamel Coating And Cathodic Protection, Liang Fan, Signo Tadeu Dos Reis, Genda Chen, Michael L. Koenigstein

Materials Science and Engineering Faculty Research & Creative Works

This paper presents the first report on the corrosion resistance of pipeline steel with damaged enamel coating and cathodic protection in 3.5 wt % NaCl solution. In particular, dual cells are set up to separate the solution in contact with the damaged and intact enamel coating areas, to produce a local corrosion resistance measurement for the first time. Enamel-coated steel samples, with two levels of cathodic protection, are tested to investigate their impedance by electrochemical impedance spectroscopy (EIS) and their cathodic current demand by a potentiostatic test. Due to its glass transition temperature, the enamel-coated pipeline can be operated on …

Surface Area And Electrocatalytic Properties Of Feni Nanoparticles For The Oxygen Evolution Reaction (Oer), James Burrow

Chemical Engineering Undergraduate Honors Theses

Iron-nickel bimetallic electrocatalysts have recently emerged as some of the best candidates for the oxygen evolution reaction (OER) in alkaline electrolyte. Understanding the effects of composition and morphology of iron-nickel nanoparticles is crucial for optimization and enhanced electrocatalyst performance. Both physical surface area and electrochemical surface area (ECSA) are functions of morphology. In this study, four different iron-nickel nanoparticle catalysts were synthesized. The catalysts were varied based on morphology (alloy versus core-shell) and composition (low, medium, and high stabilizer concentration). Brunauer-Emmett-Teller (BET) surface area analysis was conducted on three of the synthesized iron-nickel nanoparticles using a physisorption analyzer while electrochemical …