Materials Science and Engineering Commons^™

Structure Morphology And Optical Properties Of Nanocrystalline Ga2o3 Thin Films, Sampath Kumar Samala

Open Access Theses & Dissertations

Gallium Oxide thin films were produced by sputter deposition by varying the substrate temperature (T_s) in a wide range (T_s=25-800 oC) and under variable deposition time. The structural characteristics and optical properties of Ga₂O₃ films were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Rutherford backscattering spectrometry (RBS) and spectrophotometric measurements. The effect of growth temperature is significant on the chemistry, crystal structure and morphology of Ga₂O₃ films. XRD and SEM analyses indicate that the Ga₂O₃ films grown at lower temperatures were …

Ultrasonic Wave Propagation Assessment Of Native Cartilage Explants And Hydrogel Scaffolds For Tissue Engineering, Sean S. Kohles, Shelley S. Mason, Anya P. Adams, Robert J. Berg, Jessica Blank, Fay Gibson, Johnathan Righetti, Lesha S. Washington, Asit K. Saha

Mechanical and Materials Engineering Faculty Publications and Presentations

Non-destructive techniques characterising the mechanical properties of cells, tissues, and biomaterials provide baseline metrics for tissue engineering design. Ultrasonic wave propagation and attenuation has previously demonstrated the dynamics of extracellular matrix synthesis in chondrocyte-seeded hydrogel constructs. In this paper, we describe an ultrasonic method to analyse two of the construct elements used to engineer articular cartilage in real-time, native cartilage explants and an agarose biomaterial. Results indicated a similarity in wave propagation velocity ranges for both longitudinal (1500-1745 m/s) and transverse (350-950 m/s) waveforms. Future work will apply an acoustoelastic analysis to distinguish between the fluid and solid properties including …

Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman

Mathematics Faculty Publications

Dewetting of pulsed-laser irradiated, thin (< 20 nm), optically reflective metallic bilayers on an optically transparent substrate with a reflective support layer is studied within the lubrication equations model. A steady-state bilayer film thickness (h) dependent temperature profile is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Large thermocapillary forces are observed along the plane of the liquid-liquid and liquid-gas interfaces due to this h-dependent temperature, which, in turn, is strongly influenced by the h-dependent laser light reflection and absorption. Consequently the dewetting is a result of the competition between thermocapillary and intermolecular forces. A linear analysis of the dewetting length scales established that the non-isothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational non-linear dynamics study of the dewetting pathway was performed for Ag/Co and Co/Ag bilayer systems to predict the morphology evolution. We found that the systems evolve towards formation of different morphologies, including core-shell, embedded, or stacked nanostructure morphologies.

A Framework For Studying The Physical Degradation Characteristics Of Dvds And Their Relationship To Digital Errors, Brian K. Saville

Theses and Dissertations

The methods used to store data on DVD-R discs have been proven to work over the last 15 years. However, there has been a growing concern that these discs will be outlasted by the paper records they were meant to replace. The data on a DVD-R is stored as optical contrasts which have the potential to be misread and even damaged. This damage may occur either on the surface or internally to the disc, especially on the recording layer itself. The literature is saturated with studies attempting to determine the time period in which discs may fail and what the …

Effect Of Extracellular Matrix (Ecm) Protein Micropatterns On The Behavior Of Human Neuroblastoma Cells, Ishwari Poudel

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Recent advances in patterning techniques and emerging surface microtechnologies have allowed cell micropatterning to control spatial location of the cells on a surface as well as cell shape, attachment area, and number of contacting neighbor cells. These parameters play important roles in cell cellular behaviors. Cell micropatterning has thus become one of the most important strategies for biomedical applications, such as, tissue engineering, diagnostic immunoassays, lab-on-chip devices, bio-sensing, etc., and cell biology studies as well. For neuronal cells, there have been attempts to distribute neuronal cells on specific patterns to control cell-to-cell interaction. However, there have been very limited understanding …

A Conceptual Framework And Simulation Modeling Of Engineering Change Management In A Collaborative Environment, Krishna Rao Reddi

Mechanical and Aerospace Engineering - Dissertations

Engineering Change Management (ECM) in a collaborative environment is a complex process and is crucial to the Original Equipment Manufacturer (OEM) to ensure low product development time and cost. In this thesis, the ECM in a collaborative environment has been studied and a conceptual framework to support the process is presented. New Product Development (NPD) and ECM processes have been modeled and simulated to study the associated process dynamics.

An extensive review of the literature indicated that the research on ECM in a collaborative environment is very limited. The review also highlighted that, (i) the ECM frameworks from past research …

Highly Porous Silica Network Prepared From Sodium Metasilicate, R E. Essien, O A. Olaniyi, L A. Adams, R O. Shaibu

Journal of Metals, Materials and Minerals

Porous silica network was prepared from sodium metasilicate (Na2SiO3) at room temperature (27C) using hydrochloric acid (HCl) as catalyst through the sol-gel method. The gel was dried at 120C for 1 day and calcined at 800C for 3 hours and the material obtained characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results showed the formation of amorphous silica particles of average sizes 598 nm with ordered porous network of pore sizes ranging from 0.18-0.91 ?m. This synthetic route uses sodium metasilicate as commercial precursor without pore forming templates which could be useful …

Surface Wetting And Friction Studies Of Nano-Engineered Surfaces On Copper Substrate, Julius Sheldon Morehead

Graduate Theses and Dissertations

Nano-engineered-textures on a material surface can dramatically improve the wetting and non-wetting properties of a surface, and they also show promise to address friction issues that affect surfaces in contact. In this work, aluminum-induced crystallization (AIC) of amorphous silicon (a-Si) was used to produce nano-textures on copper (Cu) substrates. A study was performed to examine the effects of changing the annealing conditions and a-Si thickness on nano-texture formation. The creation of various nano-topographies and chemically modifying them using octafluorocyclobutane (C4F8) was performed to control hydrophilicity, hydrophobicity, and oil affinity of nano-textured surfaces. A video-based contact angle measurement system was used …

Fundamental Understanding Of Soot Induced Wear Mechanism Of Diesel Engines, Mihir Patel

Material Science and Engineering Dissertations - Archive

Emission of Oxides of nitrogen and particulates matters from diesel engines have been reduced by implementing exhaust gas recirculation (EGR) protocols but at the expense of increased wear of engine components. This problem is aggravated by Environment Protection Agency (EPA) regulation such as API CJ 4 and SAPS where chemical limits have been places on the amount of phosphorous, sulfur and sulfated ash in lubrication oil. Several studies have examined the role played by diesel soot on enhanced wear but none have provided comprehensive mechanism. This would allow the possibility to comprehend fundamental understanding of soot induced wear mechanism of …

Templated Synthesis And Characterizations Of High Moment Magnetic Nanoparticles For Bioapplications, Punnapob Punnakitikashem

Material Science and Engineering Dissertations - Archive

Magnetic nanoparticles have been widely used for biomedical applications such as drug and gene delivery, hyperthermia treatment of cancer, MRI contrast enhancement, cell labeling and magnetic separation. We present two new types of magnetic nanoparticles for bioapplications; granular superparamagnetic gold nanoparticles and multilayered nanodisks. Granular superparamagnetic gold nanoparticles consist of superparamagnetic islands embedded in a gold matrix. Multilayered nanodisks consist of two magnetic layers separated by a non-magnetic layer with two capping layers. Capping layers such as gold provide functionalization sites for biomolecule attachment. These nanoparticles possess two key magnetic requirements for bioapplications, a high saturation magnetic moment and a …

An Innovative Epitaxial Growth Method For Minimizing Dislocations In Thin-Film Quantum-Dot Optoelectronic And Photovoltaic Device Applications, Jateen Gandhi

Material Science and Engineering Dissertations - Archive

A new buffer layer method for epitaxial growth of lattice-mismatched semiconductor quantum-dots based p-i-n structures is presented. To our knowledge this is the first instance of a dislocation-reduction approach that has shown reduced dark current behavior in a quantumdot device compared to its counterpart homojunction p-n device consisted of the barrier material. The present work compared a lattice misfit strain build-up behavior between an In0.15Ga0.85As (p) / InAs (i) / In0.15Ga0.85As (n) (QD) device to an In0.15Ga0.85As (p) / In0.15Ga0.85As (n) (HOM) device, as both were grown on an un-doped gallium arsenide (GaAs) (100) substrate. The intrinsic region of QD …

Electrochemical N-Type Doping In Metal Oxides And Its Application In Photovoltaics, Xiaofei Han

Material Science and Engineering Dissertations - Archive

Electrodeposition has the advantages of low-cost, high-throughput and large-area processing which is particularly suitable for solar cells fabrication. Two common metal oxides prepared by electrodeposition are discussed here, ZnO and Cu2O. ZnO is largely used in the solar cells as the window and transparent contact material. Cu2O is potential absorption material for next generation solar cell. n-type doping of these metal oxides was revealed during electrochemical deposition. For naturally n-type ZnO, n-type doping is achieved by substituting the cation (Zn) with a group III element (Al, Ga and Y) and for naturally p-type Cu2O, n-type doping is realized by substituting …

Spectral Engineering Of Optical Fiber Through Active Nanoparticle Doping, Tiffany Lindstrom-James

All Dissertations

The spectral engineering of optical fiber is a method of intentional doping of the core region in order to absorb/emit specific wavelengths of light therby providing enhanced performance over current fibers. Efforts here focused on developing an understanding of optically active nanoparticles based on alkaline earth fluorides that could be easily and homogeneously incorporated into the core of a silica based optical fiber preform and result in efficient and tailorable spectral emissions.
Doped and undoped calcium, strontium and barium fluoride nanoparticles were successfully synthesized and characterized for their physical, chemical, and optical behavior. Distinct spectroscopic differences as a result of …

Strength Of Polycrystalline Ceramics Under Shock Compression, Jianbin Zhu

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Determinations of Some polycrystalline ceramics’ strength properties and inelastic deformation mechanisms in the shocked state are critically important to the design and optimization of armor structures involving these materials. In this work, multiscale modeling and simulations have been carried out to study strength of the effects of polycrystalline microstructure, crystal anisotropy, porosity, and their interactions with microscopic deformation/damage mechanisms on the responses of several polycrystalline ceramics under shock compression and to extract their shock strengths from the wave profiles measured in the related plate impact shock wave experiments.

With a mesoscopic computational model, the roles of intragranular microplasticity and deformation …

Influence Of Aging And Severe Plastic Deformation On The Shape Memory Behavior Of Ti-50.6at%Ni, William Shirley

All Theses

Martensitic phase transformations were investigated for Ti -50.6 at % Ni processed via severe plastic deformation (SPD) and subsequent aging for temperatures between 400 and 550C and times ranging from 1hr to 100hrs. Phase transformations of the SPD material were compared to material processed via solution treated at 800C and 850C for 1hr. Transformations were investigated with differential scanning calorimetry (DSC) and confirmed by X-ray diffraction (XRD) with optical microscopy being used to determine grain size. Solution treated samples displayed a single (1-1) B2↔B19' transformation prior to and upon initial aging, i.e. 400C/1h, 450C/1/10h. Intermediate aging conditions, 450C/100h; 500C/1/10/100h; and …

Role Of Surface Coatings In Lithium-Ion Batteries, Archana Kayyar

All Theses

Rechargeable batteries that can charge and discharge at high rates have applications in hybrid and plug-in hybrid vehicles and they provide energy storages for wind energy. Various methods like reducing particle size, aliovalent doping and carbon coating have been researched in order to attain higher charge and discharge rates in rechargeable Li-ion batteries. In this work, the electrode materials were coated with amorphous films in an attempt to improve the rate capability of the batteries.
A study by Kang and Ceder suggested that a Li₄P₂O₇-like 'fast-ion conducting surface phase' could form on the surface …

Printing Carbon Nanotube Based Supercapacitors For Packaging, Alexandra Hartman

All Theses

Living in a world full of portable electronics, there is great need for energy storage devices. Currently, limitations for storage involve power inefficiencies as well as bulkiness. This is why printable charge storage devices that display good electrochemical performance are needed. It is for this reason that research into the production and packaging of carbon nanotube based super capacitors was carried out.
A super capacitor can be built by using high surface area multi-walled carbon nanotubes suspended in an ionic liquid. The two active electrodes are made from a combination of the multi-walled carbon nanotubes and an ionic liquid, ground …

The Development Of A Far Red To Near Infrared Fluorescent Probe For Use In Optical Imaging, Margaret Fiedler

All Theses

New techniques for biological optical imaging are of great interest for the detection and visualization of processes and disease in both clinical and research areas. One major advancement has been the use of far red and near infrared (NIR) light, as it has the ability to penetrate tissues deeper than other parts of the spectrum which are readily scatter and absorbed by the surroundings. In order to improve the signal to noise ratio and resolution of optical images, contrast agents are used. Fluorescent markers can be modified to attach to specific molecular targets, creating small molecular probes. These targets can …

Effect Of Selected Phase Change Materials Concentration And Manufacturing Process On The Properties Of Plaster Mixture Systems, Rong Cui

All Theses

Phase change materials (PCM) are generally used in building construction materials for their ability to absorb and release large amounts of energy when their phase change happens at their specific melting temperature. This results in a significant increase in thermal mass of the building, a reduction in temperature fluctuations and therefore a reduction in heating and cooling loads. However, in order to properly select a PCM and optimize its integration in a specific building, the properties of building construction materials enhanced with PCM must be known. This research focuses on studying the effects of the concentration of a micro-encapsulated PCM …

Effects Of Grain Boundary Character On Dynamic Recrystallization Using A Modified Monte Carlo Method, Michael B. Morse

Boise State University Theses and Dissertations

Dynamic recrystallization (DRX) is the recrystallization that occurs during high temperature deformation of metals and alloys. While DRX has been observed experimentally, the parameters that affect the microstructure are still being explored. For example, the effects of temperature, strain rate, and initial grain size have already been studied, yet the effect of initial special boundary fraction is still unknown. Special boundaries are high-angle, low-energy grain boundaries. It is believed that higher initial fractions of special boundaries will lead to a delay in the onset of recrystallization and a higher peak stress.

Experimentation has shown that triple junctions are preferred nucleation …