Materials Science and Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

Conversion Of Secondary Pulp And Paper Sludge To Glucose By Hydrothermal Treatment, N Chariyaprasertsin, Y Matsumura, T Charinpanitkul

Journal of Metals, Materials and Minerals

Secondary pulp/paper sludge is residue from water treatment process of the paper industry. Main components of secondary pulp/paper sludge are cellulose, hemicelluose, lignin and calcium carbonate (CaCO3). The cellulose and hemicellulose could be converted to glucose by hydrothermal treatment in a stainless steel tubular batch reactor. It was found that dried powder of secondary pulp/paper sludge with nominal size in a range of 595 to 840 m contains different content of CaCO3. Therefore, effect of CaCO3 content on glucose yields was examined under designated temperature of 200-260 C and treating time of 0-40 minutes. Identification and quantification of glucose and …

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 …

Plastic Response Of Dislocation Glide In Solid Helium Under Dc Strain-Rate Loading, Caizhi Zhou, Jungjung Su, Matthias J. Graf, Charles J. Olson Reichhardt, Alexander V. Balatsky, Irene J. Beyerlein

Materials Science and Engineering Faculty Research & Creative Works

We develop a model for the gliding of dislocations and plasticity in solid ⁴He. This model takes into account the Peierls barrier, multiplication and interaction of dislocations, as well as classical thermally and mechanically activated processes leading to dislocation glide. We specifically examine the dc stress-strain curve and how it is affected by temperature, strain rate, and dislocation density. As a function of temperature and shear strain, we observe plastic deformation and discuss how this may be related to the experimental observation of elastic anomalies in solid hcp ⁴He that have been discussed in connection with the possibility …

A Multi-Scale Approach To A Greater Understanding Of The Behavior Of Heterogeneous Materials Under Dynamic Loading, Andrew J. Van Vooren

Master's Theses (2009 -)

The penetration of granular materials is of interest to a variety of different fields, and is an active area of research. The objective of this project is to gain understanding of the dynamics of a projectile penetrating into a granular material. To do this, experiments were run and a numerical model was created.

A dart gun was used to accelerate an aluminum dart to velocities around 100 m/s, which then impacted a target tank filled with Ottawa sand. The dart flew along a view window, which allowed for a recording of the penetration event using a high speed camera. Pressure …

Characterization Of Diamond-Like Carbon (Dlc) Films Deposited By Filtered Cathodic Vacuum Arc Technique, N Konkhunthot, C Euaruksakul, P Photongkam, P Wongpanya

Journal of Metals, Materials and Minerals

Diamond-like carbon (DLC) films were prepared on AISI H13 hot-work tool steel substrates by filtered cathodic vacuum arc (FCVA) technique under variable substrate DC biasing. The atomic structures of the films were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy, and near edge x-ray absorption fine structure spectroscopy. The Raman spectra revealed that when the magnitude of the bias voltage increased, the G peak was shifted toward lower wave numbers, and indicated that the sp3 content in the DLC films increased. The ratios between the sp3 and sp2 bonds in the films were verified by X-ray photoelectron spectroscopy, and the analyses …

Crystallization Behavior Of Pla In Pla/Nr Compared With Dynamic Vulcanized Pla/Nr, C Thongpin, S Klatsuwan, P Borkchaiyapoom, S Thongkamwong

Journal of Metals, Materials and Minerals

PLA has been an interesting biopolymer widely used in various applications. It has been widely known that crystallization of PLA is rather slow. After melt processing, crystallinity of PLA could be lost. The study of PLA added with fibers, particles or even nano-particles has been studied extensively. Nonetheless, the suffering in some mechanical characteristic such as toughness has been encountered. Our research was aimed to enhance toughness of PLA by melt blending NR, and dynamic vulcanized NR into PLA using an internal mixer. PLA:NR and PLA:NR vulcanizate with the ratio of 90:10, 80:20, 70:30, 60:40 and 50:50 were studied. Crystallization …

Dissolved Oxygen Sensor Film Using Ruthenium Polypyridine Complex As Luminophore, C Su-Ngam, Sh Thang, A Wongchaisuwat, L Meesuk

Journal of Metals, Materials and Minerals

Ruthenium polypyridine complex was synthesized by using RAFT process. The Ruthenium was immobilized in 2 silicone matrices, polydimethylsiloxane(PDMS) and KE 200 (silicone elastomer base)/CX200 (curing agent). KE 200/CX200 is the alcohols curing type silicone. Both sensor films showed absorption peak at 460 nm and luminescence peak at 610 nm. The KE200/CX200 film gave linear response to dissolved oxygen up to 80% O2 (18 ppm) follow Stern-Volmer equation with R2 of 0.990. The measured luminescence intensity decreased with increasing dissolved oxygen water temperature from 25 to 70c. After being irradiated with 460 nm light source for 3 hrs, the sensor film …

Low Temperature Chemical Precipitation And Characterization Of Ceria Based Ceramic Composite Oxide Materials, D Radhika, A Samson Nesaraj

Journal of Metals, Materials and Minerals

Ceria based ceramic composite oxide materials such as Ce0.9Gd0.1O2-δ -Ce0.9Y0.1O2-δ and Ce0.8Gd0.2O2-δCe0.8Y0.2O2-δ were prepared by a simple chemical precipitation method for application in low temperature solid oxide fuel cells (LTSOFCs) as electrolytes. The precursor materials used in this synthesis were cerium nitrate hexahydrate, gadolinium nitrate and yttrium nitrate (as basic materials), sodium hydroxide (as precipitator material) and PVA (as surfactant). A mixture of metal hydroxides was formed when the aqueous mixture of basic materials mixed with the aqueous precipitant solution in proper stoichiometric composition. The resultant hydroxide mixture was washed with ethanol and water mixture (1:9 volume ratio) to remove …

Halogenated Sorbitol Derivatives Using As Nucleating Agent And Their Effect On Orientation Of Polypropylene Fiber, T Sutthatang, S Wangsoub

Journal of Metals, Materials and Minerals

In this work, two halogenated derivatives of benzylidene sorbitol were synthesized by reacting D-sorbitol with an aromatic aldehyde in the present of an acid catalyst. ie.chloro and bromo derivatives for using as nucleating agent for polypropylene. For chloro derivative, different positions of substituent (ortho, meta and para) were also synthesised. SEM and TEM micrographs of gel extracted from organic solvent revealed long fibril network of chloro and bromo substitutes which their diameters are in the range of about 10-200 nm. Small amount (0.1-1%wt) of these materials was blended with isotactic polypropylene (iPP) by two roll mill machine and the mixture …

Parameters Optimization Of Copper Wire Bonding On Thin Small Outline Package, S Srikamonsirisak, U Tantinuchawong, Y Satirakul

Journal of Metals, Materials and Minerals

With significant rising of Au price, there is growing demand to implement Cu wire bonding as an alternative method for Au wire bonding. However, there are several challenges to overcome because Cu is easily oxidized and its property is harder than Au. The oxidation deteriorates bondability and bond reliability, while the greater wire hardness leads to the more severe wire bonding parameters (higher force, higher power, higher temperature), which results in physical damage of the bond pad and underlying layers. This paper reveals wire bonding parameters optimization in order to implement Cu wire bonding in high volume production environment with …

Titanium Dioxide Nanostructures Synthesized By Sonochemical Hydrothermal Process, N Wongpisutpaisan, C Kahattha, N Vittayakorn, A Ruangphanit, W Pecharapa

Journal of Metals, Materials and Minerals

Titanium dioxide particles were prepared by sonochemicalhydrothermal process from a precursor of titanium isopropoxide in the presence of polyvinyl alcohol aqueous solution. Sonication of the precursor was conducted using sonic horn operated at 20 kHz until the completely precipitated product was reached. As-obtained intermediate products were then loaded into a Teflon-lined stainless steel autoclave for hydrothermal process with10M NaOH aqueous solution and heated under different temperature 80-120C. The synthesized products were characterized of structural properties and surface morphology by X-ray diffraction spectroscopy and field emission scanning electron microscope. The results show that prepared samples have a good crystallinity and the …

Application Of Para Rubber Latex Mixed With Organic Dyes As Printing Ink For Biodegradable Plastic Film, T Techochaingam, S Netpradit, K Tanprasert, P Boochathum

Journal of Metals, Materials and Minerals

content of 35.9% and 41.2%, which had the viscosity of 9.52 seconds and drying time of around 5 minutes. The viscosity of Para rubber latex with solid content of 59.0% and 61.4% was very high; thus, resulted in coagulation. Then modified rubber latex CNR with solid content of 16.5%, 19.2%, 26.8% and 28.2%, which had the viscosity around 8.30 seconds and drying time of around 5 minutes. Dye solution was prepared by adding 1 part of dye to 1 part of water (w/w). The formulation of ink that yielded the highest optical density of 1.43 was 8.4 g dye solution …

Macrostructure Modeling Of Al-20 % Sn Alloy, P Padhi, Ak Sahoo, S Kar

Journal of Metals, Materials and Minerals

In metallic alloys, the formation of macrostructure involves different length and time scales. The macrostructure strongly influences the mechanical properties of the materials. Modeling of macrostructure provides valuable insights for tailoring of the structure. In the present study simulation of macrostructure in Al-20Sn has been carried out. Expression for nucleation rate and growth rate were tuned to get a match with the experimentally observed macrostructure. The study incorporates the motion of grains due to Brownian motion. Incorporation of Brownian motion resulted in more uniform distribution locally, which has been experimentally observed. Both simulation and macrograph showed few columnar grains and …

Upconversion Luminescence Of Yttrium Oxysulfide Co-Doped With Rare Earth Elements, U Injarean, P Pichestapong, T Ruangsiritanyakul, S Tayaniphant

Journal of Metals, Materials and Minerals

Rare earth ions doped upconversion phosphors have been used in many applications such as infrared laser detecting, anti-counterfeit protection and solid state display. In this study, yttrium oxysulfide (Y2O2S) compounds co-doped with rare earth elements, ytterbium (Yb), and one of the following elements, erbium (Er), thulium (Tm), europium (Eu) or holmium (Ho) were synthesized from doped rare earth oxides using sulfide fusion method with pelletization pretreatment. The doping was carried out with the mixing of yttrium nitrate and rare earth nitrate solutions to obtain homogeneous mixture. The mixed nitrate solution was precipitated with oxalic acid and calcined to doped oxide …

Improving The Efficiency Of P3ht:Icba Organic Solar Cells By Modifying The Photoactive Solution Preparation Step, Matthew Blaine Samson

Electrical & Computer Engineering Theses & Dissertations

Organic solar cells (OSCs) are a promising alternative to conventional silicon solar cells. These organic devices offer the promise of facile low cost large scale solution based processing on lightweight, flexible, plastic substrates. At the present state of the technology, however, OSCs exhibit relatively low power conversion efficiencies. To improve these efficiencies, new materials are constantly being developed.

One such material is the fullerene indene-C₆₀ bisadduct (ICBA). When implemented in a poly(3-hexylthiophene-2, 5-diyl) (P3HT) : ICBA bulk heterojunction solar cell, these devices exhibit open circuit voltages exceeding 0.8 V, a value much higher than the devices made implementing phenyl-C …

Improving The Stability Of High And Low Bandgap Polymers Organic Photovoltaic Devices Using A Solution Based Titanium Sub-Oxide Interfacial Layer, Kurniawan Foe

Electrical & Computer Engineering Theses & Dissertations

The improvement in device efficiency has brought organic photovoltaic (OPV) devices closer to commercial viability, highlighting the importance of studying the lifetime and stability of OPV devices. At present, the lifetime and stability of OPV devices is much shorter and poor mainly caused by oxygen, moisture, and light resulting in the oxidation on low work function electrodes and the degradation of the morphology of the photoactive layer. To improve the lifetime and stability of the OPV devices, we used newly developed low bandgap polymer, PCDTBT, as the electron acceptor material and a solution based titanium sub-oxide (TiOx) interfacial layer inserted …

Complementarities Of Probabilistic And Evidence Approaches: An Uncertainty Assessment For Selection Of Composite Material, Stella B. Bondi, Resit Unal, Patrick T. Hester, Trina M. Chytka

Engineering Technology Faculty Publications

A complimentary probabilistic and evidence theory approach is utilized to enhance uncertainty assessments in the area of critical safety characteristics for conceptual design. This research provides additional exploration into the failure modes necessary to utilize Fiber Reinforced Polymer (FRP) and various composites to their fullest potential and to minimize uncertainty by comparing probability and evidence theories. This combined approach has been applied to a selection of composite material that could provide uncertainty assessment design for a space transportation system. Uncertainty estimates presented are bounded by belief and plausibility functions. The results may provide additional information to the decision makers in …

Field Emission Studies Toward Improving The Performance Of Dc High Voltage Photoelectron Guns, Mahzad Bastaninejad

Mechanical & Aerospace Engineering Theses & Dissertations

Field emission is the main mechanism that prevents DC high voltage photoemission electron guns from operating at the very high bias voltages required to produce low emittance beams. Gas conditioning is shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. The field emission characteristics of 5 stainless steel electrodes varied significantly upon the initial application of voltage but improved to nearly the same level …

Structural Reliability Analysis Of Corroded Steel Girder Bridge, Mohammed Shaalan Al Badran

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The natural aging, environmental impact, and appropriate design are certainly playing a serious role in safety of the bridges function. The functional safety of bridge constitutes a prime element of the transportation system serving commuters, passengers and freight. According to Federal Highway Administration, the steel bridges share represents a large amount of the United States’ bridges. In last century, the collapse of both the Silver Bridge at Point Pleasant, West Virginia over the Ohio River on December 15, 1967 and over the Mianus River Bridge in Connecticut on June 28, 1983 showed that steel corrosion has been the leading reason …

Preparation And Characterization Of A Novel Composite Electrolyte Ceria-Sulfate For Intermediate Temperature Solid Oxide Fuel Cells, Ze Tong, Yi-Mei Yin, Jie-Wei Yin, Zi-Feng Ma

Journal of Electrochemistry

A novel composite electrolyte SDC-(Li/Na)₂SO₄ was prepared for intermediate temperature solid oxide fuel cells (ITSOFC). The phase structure and cross-sectional morphology were examined by XRD and SEM, respectively, and the ionic conductivity was investigated by AC impedance in a temperature range of 400 ^oC ~ 700 ^oC in air. It was found that the composite electrolyte was composed of two phases: crystal SDC and amorphous (Li/Na)₂SO₄. The conductivity of the composite electrolyte was significantly larger than that of SDC at intermediate temperatures (550 ^oC ~ 700 ^oC) and increased …

The Effect Of Precursors On Performance Of Lini0.5Co0.2Mn0.3O2 Cathode Material, Dong-Ge Hu, Zhang-Zhi Wang, Jia-Li Liu, Tao Huang, Ai-Shui Yu

Journal of Electrochemistry

Commercial LiNi_0.5Co_0.2Mn_0.3O₂ material is generally prepared by a combination of co-precipitation and solid state reaction method. The particle size distribution and morphology of Ni_0.5Co_0.2Mn_0.3(OH)₂ precursor have a great impact on the electrochemical performance of LiNi_0.5Co_0.2Mn_0.3O₂. In this work, the crystal structure and surface morphology of LiNi_0.5Co_0.2Mn_0.3O₂ prepared by three different precursors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Particle size distribution, tap density and electrochemical performance were …