Materials Science and Engineering Commons^™

Pan Nanofibers And Nanofiber Reinforced Composites, Cheng Ren

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Nanomaterials play an important role in the development of nanotechnology. They possess unique mechanical, physical, and chemical properties coupled with small size and ultrahigh surface area that can provide critical advantages for applications. Continuous nanofibers attract special interest due to their dual nano-macro nature and ability to bridge scales. Nanofibers are being considered for a broad range of applications spanning advanced filters, separation membranes, ultrasensitive sensors, micro/nano actuators, nanoprobes, tissue engineering scaffolds, protective and smart closing, and multifunctional composites. Most of these applications require certain mechanical properties and robustness. However, the literature on the mechanical behavior of nanofibers and their …

Thermo-Mechanical Effects Of Thermal Cycled Copper Through Silicon Vias, James Marro

All Theses

The semiconductor industry is currently facing transistor scaling issues due to fabrication thresholds and quantum effects. In this 'More-Than-Moore' era, the industry is developing new ways to increase device performance, such as stacking chips for three-dimensional integrated circuits (3D-IC). The 3D-IC's superior performance over their 2D counterparts can be attributed to the use of vertical interconnects, or through silicon vias (TSV). These interconnects are much shorter, reducing signal delay. However TSVs are susceptible to various thermo-mechanical reliability concerns. Heating during fabrication and use, in conjunction with coefficient of thermal expansion mismatch between the copper TSVs and silicon substrate, create harmful …

New Approaches On Deinking Evaluations, Roland Gong

Dissertations

Paper recycling in the U.S. is the most successful program of environmental sustainability. Approximately two thirds of consumed paper products were recycled, according to the EPA and AF&PA. However, domestic mills only applied one third of recycled fibers into new products, which is much lower than reported in China (67%). The domestic recycle mills claimed that outdated facilities, poor recycled fiber quality and high manufacturing cost are the major issues. They also said that these recycle mills have been put in a “no-win” position, which threatens the whole recycling loop eventually. A case study about Chinese recycle mills has been …

Magnetic And Structural Properties Of Ni-Mn-Ga Films Produced Via Physical Vapor Tri-Deposition, Christopher Kimo Wilson

Boise State University Theses and Dissertations

The structural, thermal, magnetic, and mechanical properties of Ni-Mn-Ga magnetic shape-memory alloys depend strongly on composition. Compositions of sputter deposited films differ from the composition of the single alloy targets from which they originate, where the composition change depends on sputter parameters. Films produced via physical vapor deposition from single alloy targets have sound film-substrate adhesion and film uniformity, however, accurate control of composition is difficult. Tri-sputter deposition from multiple targets allows the flexibility of varying deposition rates and film compositions. A robust procedure with three targets (nickel, nickel-gallium, and manganese) was developed to deposit Ni-Mn-Ga films on silicon with …

Factors Controlling Synthesis Of Iron Oxide Nanoparticles And The Effect Of Surface Charge On Magnetic Hyperthermia, Bin Qi

All Dissertations

ABSTRACT
Iron oxide nanoparticles (IONPs) have been widely studied in the theranostics application due to their promising magnetic properties, low cytotoxicity and attractive biocompatibility. Despite the numerous studies on the kinetic mechanisms of IONPs synthesis and thus the resulting size, shape and crystallinity; there are still considerable unsolved issues in quantitatively depicting the dependence between particle morphology and the reaction conditions.
To begin to explain some of these phenomena, the kinetic mechanism for the morphology and crystalline changes of IONPs with the ligand/precursor ratio in nanoparticle synthesis was investigated. During the synthesis of nanoparticles via thermal decomposition of iron precursors, …

Advanced Imaging As A Novel Approach To The Characterization Of Membranes For Microfiltration Applications, Milagro Marroquin

All Dissertations

This dissertation focuses on the design, development and implementation of novel, advanced imaging protocols for the characterization of membranes in microfiltration applications. Oftentimes, membrane characterization studies are done with high resolution microscopy techniques like scanning electron microscopy or transmission electron microscopy. The results obtained by these popular imaging techniques are subject to error and their reliability might be, in some instances, compromised because they require drying and metallization of the sample; working under high vacuum and electron beam intensity; and extensive sectioning to retrieve internal information. These factors may disrupt the membrane structure or modify its features. As an alternative …

Optical And Mechanical Investigation Of Inas /Gaas Quantum Dots Solar Cells And Inas Nanowires For The Application Of Photovoltaic Device, Yushuai Dai

Theses

Self-assembled quantum dots (QDs) and nanowires (NWs) are currently the subjects of extensive study due to their promising applications in optoelectronic devices. In order to enhance understanding of the short circuit current improvement in InAs/GaAs quantum dots solar cell (QDSC), the mechanisms of carrier escape by thermal activation and tunneling from InAs quantum dots (QDs) confinements in InAs/GaAs QDSCs are investigated. The fitted activation energy of electrons from temperature dependent photoluminescence (TDPL) is 114 meV. Using this fitted activation energy, calculated thermal escape time and tunneling time of electrons from the ground state of the QDs are 10-12 seconds and …

3d Modeling And Design Optimization Of Rod Shaped Ionic Polymer Metal Composite Actuator, Siul A. Ruiz

UNLV Theses, Dissertations, Professional Papers, and Capstones

Ionic polymer-metal composites (IPMCs) are some of the most well-known electro-active polymers. This is due to their large deformation provided a relatively low voltage source. IPMCs have been acknowledged as a potential candidate for biomedical applications such as cardiac catheters and surgical probes; however, there is still no existing mass manufacturing of IPMCs. This study intends to provide a theoretical framework which could be used to design practical purpose IPMCs depending on the end users interest.

This study begins by investigating methodologies used to develop quantify the physical actuation of an IPMC in 3-dimensional space. This approach is taken in …

Synthesis And Characterization Of Thermally Responsive Polymer Layers, Michael Seeber

All Dissertations

Future devices such as biomedical and microfluidic devices, to a large extent, will depend on the interactions between the device surfaces and the contacting liquid. Further, biological liquids containing proteins call for controllable interactions between devices and such proteins, however the bulk material must retain the inherent mechanical properties from which the device was fabricated from. It is well known that surface modification is a suitable technique to tune the surface properties without sacrificing the bulk properties of the substrate.
In the present study, surface properties were modified through temperature responsive polymer layers. After the modification, the surfaces gained switchability …

Elaboration And Optimization Of Tellurite-Based Materials For Raman Gain Application, Guillaume Guery

All Dissertations

Tellurite-based oxide glasses have been investigated as promising materials for Raman gain applications, due to their good linear and nonlinear optical properties and their wide transparency windows in the near- and midwave infrared spectral region. Furthermore, their interesting thermal properties, i.e. low glass transition temperature and ability to be drawn into optical fibers, make tellurite-based glasses excellent candidates for optical fiber amplifiers. The estimation of the strength and spectral distribution of Raman gain in materials is commonly approximated from the spontaneous Raman scattering cross-section measurement. For development of tellurite-based glasses as Raman amplifiers, understanding the relationship between glass structure, vibrational …

Achieving High Strength And High Ductility In Friction Stir-Processed Cast Magnesium Alloy, Wei Yuan, Sushanta K. Panigrahi, Rajiv S. Mishra

Materials Science and Engineering Faculty Research & Creative Works

Friction stir processing (FSP) is emerging as an effective tool for microstructural modification and property enhancement. As-cast AZ91 magnesium alloy was friction stir processed with one-pass and two-pass to examine the influence of processing conditions on microstructural evolution and corresponding mechanical properties. Grain refinement accompanied with development of strong basal texture was observed for both processing conditions. Ultrafine-grained (UFG) AZ91 was achieved under two-pass FSP with fine precipitates distributed on the grain boundary. The processed UFG AZ91 exhibited a high tensile strength of ∼435 MPa (117 pct improvement) and tensile fracture elongation of ∼23 pct. The promising combination of strength …

Effect Of Zinc Galvanization On The Microstructure And Fracture Behavior Of Low And Medium Carbon Structural Steels, Ignatius C. Okafor, Ronald J. O'Malley, Kaushal R. Prayakarao, Heshmat A. Aglan

Materials Science and Engineering Faculty Research & Creative Works

Microstructure and fracture behavior of ASTM 572 Grade 65 steels used for wind tower applications have been studied. Steels of two carbon level chemistries designed for this grade were used in the study. Fracture toughness of the steels was studied using 3-point bend test on samples coated with zinc and not coated with zinc. Lower carbon steel showed higher resistance to fracture than medium carbon steel after zinc galvanization. SEM study suggests that zinc and zinc bath additives that migrated to crack tips are responsible for the loss in ductility. The phenomenon of Liquid Metal Embrittlement (LME) is suggested to …

Influence Of Strain And Strain Rate On Microstructural Evolution During Superplasticity Of Mg-Al-Zn Sheet, A. Mohan, S. K. Panigrahi, R. S. Mishra, R. Verma

Materials Science and Engineering Faculty Research & Creative Works

Strain-induced abnormal grain growth was observed along the gage length during high-temperature uniaxial tensile testing of rolled Mg-Al-Zn (AZ31) sheet. Effective strain and strain rates in biaxial forming of AZ31 sheets also affected the nature of grain growth in the formed sheet. For the uniaxial testing done at 400 C and a strain rate of 10^-1 s^-1, abnormal grain growth was prevalent in the gage sections that experienced true strain values between 0.2 and 1.0. Biaxial forming of AZ31 at 5 x 10 ^-2 s^-1 and 400 C also exhibited abnormal grain growth at the cross …

Mechanical Properties Of Polypropylene (Pp) + High-Density Polyethylene (Hdpe) Binary Blends: Non-Isothermal Degradation Kinetics Of Pp + Hdpe (80/20) Blends, Kamil Sirin, Fatih Dogan, Murat Canli, Mesut Yavuz

Materials Science and Engineering Faculty Research & Creative Works

In this study, the mechanical properties and non-isothermal degradation kinetics of polypropylene (PP), high-density polyethylene (HDPE) with dilauroyl peroxide and their blends in different mixture ratios were investigated. The effects of adding dilauroyl peroxide (0–0.20 wt.%) on the mechanical and thermal properties of PP + HDPE blends have been studied. On the other hand, the kinetics of the thermal degradation and thermal oxidative degradation of PP + HDPE (80/20 wt.%) blends were studied in different atmospheres, to analyze their thermal stability. The kinetic and thermodynamic parameters such as the activation energy, Ea., the pre-exponential factor, A, the reaction order, n, …

Electrospun Nanofiber Yarns For Nanofluidic Applications, Chen-Chih Tsai

All Dissertations

This dissertation is centered on the development and characterization of electrospun nanofiber probes. These probes are envisioned to act like sponges, drawing up fluids from microcapillaries, small organisms, and, ideally, from a single cell. Thus, the probe performance significantly depends on the materials ability to readily absorb liquids. Electrospun nanofibers gained much attention in recent decades, and have been applied in biomedical, textile, filtration, and military applications. However, most nanofibers are produced in the form of randomly deposited non-woven fiber mats. Recently, different electrospinning setups have been proposed to control alignment of electrospun nanofibers. However, reproducibility of the mechanical and …

55th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 55th annual meeting of the Rocky Mountain Conference on Magnetic Resonance, co-endorsed by the Colorado Section of the American Chemical Society and the Society for Applied Spectroscopy. Held in Denver, Colorado, July 28 - August 1, 2013.

Constructing And Optimizing A Single Wafer Solar Cell Array In The Microfabrication Lab At California Polytechnic State University At San Luis Obispo, Rod Marstell

Master's Theses

CONSTRUCTING AND OPTIMIZING A SINGLE WAFER SOLAR CELL ARRAY IN THE MICROFABRICATION LAB AT CALIFORNIA POLYTECHNIC STATE UNIVERSITY AT SAN LUIS OBISPO

Solar cells are more and more becoming a significant source of energy in the world today. They are used to power entire buildings as well as small devices and everything in between, and are utilized all around the world. Smaller solar devices, such as hearing aid battery chargers, cost a lot of money relative to the monetary wealth in third-world countries. For this purpose, a less expensive, more efficient solar cell array should be developed.

This study contains …

Influence Of Calcium Carbonate Nanoparticles On Mechanical Behavior Of Poly(Lactic Acid)/Poly(Butylene Succinate) Blend, N Hongsriphan, T Burirat, P Niratsungnern, S Trongteng

Journal of Metals, Materials and Minerals

PLA/PBS blends in various blend ratio (70:30, 50:50, and 30:70 wt%) containing calcium carbonate nanoparticles (nano-CaCO3) of 1 and 5 phr were prepared. Tensile tests with 3 strain rates and Izod impact test were carried out in order to investigate the influence of CaCO3 nanoparticles on mechanical behavior of nanocomposites under different deformation rates. Morphology and compatibility of nanocomposites were studied using SEM and DSC. It is found that PBS/PLA 50/50 wt% blends exhibited the highest percentage of elongation at break due to co-continuous phases as seen in SEM. CaCO3 nanoparticles were dispersed uniformly in polymer matrix although they showed …

Fe, Co And Ni Adatoms Adsorbed On Silicene: A Dft Study, Kent Gang '14, Siva Gangavarapu '14, Matthew Deng '14, Glenn W. "Max" Mcgee, Ron Hurlbut, Michael Lee Dao Kang, Sean Ng Peng Nam, Harman Johll, Tok Eng Soon

Student Publications & Research

Two-dimensional materials have attracted much research attention given their intriguing properties. The latest member of this class of materials is silicene. In this work, we investigate the adsorption of Fe, Co and Ni adatoms on silicene using plane-wave density functional theory calculations within the Perdew-Burke-Ernzerhof parameterization of the generalized gradient approximation for the exchange-correlation potential. In particular, we calculate the binding energy, magnetization, and projected electronic configurations of these adatoms adsorbed at different sites on the silicene. Our calculations show that the hole site (i.e. in the centre of a hexagonal-like arrangement of Si atoms) is the most stable configuration …

Chitosan Derivative-Based Hemostat: Irritation, Hypersensitivity And Absorbability Study, B Thavornyutikarn, W Kosorn, P Surattanawanich, U Wongparami, W Janvikul

Journal of Metals, Materials and Minerals

The objective of this study was to evaluate the safety of a carboxymethylchitosan-based hemostatic prototype for internal use, in terms of irritation, hypersensitivity and absorbability. Skin irritation and delayed-type hypersensitivity tests of the prototype in humans (n=30) were assessed by a patch test method. The human skin sites were graded and photographed after patch removal at each time point using a 4-point (0-3+) grading scale of increasing irritation related to ISO 10993-10:2002(E) and a 6-point grading scale of increasing allergy related to International Contact Dermatitis Research Group (ICDRG). The results demonstrated that the chitosan derivative-based hemostat did not cause skin …