Materials Science and Engineering Commons^™

High-Productivity Membrane Adsorbers: Polymer Surface-Modification Studies For Ion-Exchange And Affinity Bioseparations, Heather Chenette

All Dissertations

This Dissertation centers on the surface-modification of macroporous membranes to make them selective adsorbers for different proteins, and the analysis of the performance of these membranes relative to existing technology. Traditional chromatographic separations for the isolation and purification of proteins implement a column packed with resin beads or gel media that contain specific binding ligands on their exposed surface area. The productivity of this process is balanced by the effective use of the binding sites within the column and the speed at which the separation can take place, in addition to the need to maintain sufficient protein purity and bioactivity. …

Photo-Sensitivity Of Large Area Physical Vapor Deposited Mono And Bilayer Mos2, Baoming Wang, Christopher Muratore, Andrey A. Voevodin, M. Amanul Haque

Chemical and Materials Engineering Faculty Publications

We present photosensitivity in large area physical vapour deposited mono and bi-layer MoS2 films. Photo-voltaic effect was observed in single layer MoS2 without any apparent rectifying junctions, making device fabrication straightforward. For bi-layers, no such effect was present, suggesting strong size effect in light-matter interaction. The photo-voltaic effect was observed to highly direction dependent in the film plane, which suggests that the oblique deposition configuration plays a key role in developing the rectifying potential gradient. To the best of our knowledge, this is the first report of any large area and transfer free MoS2 photo device with performance comparable to …

A Soft Condensed Matter Approach Towards Mathematical Modelling Of Mass Transport And Swelling In Food Grains, Michael Chapwanya, N. Misra

Articles

Soft condensed matter (SCM) physics has recently gained importance for a large class of engineering materials. The treatment of food materials from a soft matter perspective, however, is only at the surface and is gaining importance for understanding the complex phenomena and structure of foods. In this work, we present a theoretical treatment of navy beans from a SCM perspective to describe the hydration kinetics. We solve the transport equations within a porous matrix and employ the Flory–Huggin’s equation for polymer–solvent mixture to balance the osmotic pressure. The swelling of the legume seed is modelled as a moving boundary with …

An Experimental Investigation Towards Improvement Of Thermoelectric Properties Of Strontium Titanate Ceramics, Arash Mehdizadeh Dehkordi

All Dissertations

The direct energy conversion between heat and electricity based on thermoelectric effects is a topic of long-standing interest in condensed matter materials science. Experimental and theoretical investigations in order to understand the mechanisms involved and to improve the materials properties and conversion efficiency have been ongoing for more than half a century. While significant achievements have been accomplished in improving the properties of conventional heavy element based materials (such as Bi$_2$Te$_3$ and PbTe) as well as the discovery of new materials systems for the close-to-room temperature and intermediate temperatures, high-temperature applications of thermoelectrics is still limited to one materials system, …

Replacement Of Solvent Based Ink By Water Based Inks For Gravure Presses With Low Efficiency Ink Driers, Viraj Suresh Dalvi

Masters Theses

Rotogravure printing of decorative laminates, wall coverings, or vinyl floorings process often uses solvent based inks. The main constraining factor with solvent based ink is presence of volatile organic compounds (VOC’s). Due to the environmental norms on Volatile Organic Compounds (VOCs), and restrictions on using solvent based inks, the ink industry came up with water based ink as more environmentally friendly alternative. Organizations which print decorative laminates, wall coverings, or vinyl floorings with solvent based inks have gravure printing infrastructure, which is often equipped with low efficiency driers capable of drying solvent based inks. In order to comply with environmental …

Self-Supported Printed Multi-Layer Capacitors, Michael James Joyce

Masters Theses

The increasing demand for miniaturized electronic devices has increased the need for rechargeable micro-power sources. Although lithium and lithium ion batteries have been utilized in these applications since the late 1990s, other energy harvesting technologies, such as thermal, mechanical, and solar, are now being used to augment batteries to enable systems to be self-powered. However, the lifetime of any battery is finite, which may be a major problem when the application is in a permanent structure or medical implant device. For power or significant energy storage applications, printed multilayer capacitors or supercapacitors are being explored as an enhancement, or replacement …

Synthesis Of Silicon Carbide Fibers From Polycarbosilane By Electrospinning Method, Yuan Yue

All Theses

Silicon carbide (SiC) is widely used in many fields due to its unique properties. Bulk SiC normally has a flexural strength of 500 - 550 MPa, a Vickers hardness of ~27 GPa, a Young's modulus of 380 - 430 GPa, and a thermal conductivity of approximately 120 W/mK. SiC fibers are of great interest since they are the good candidates for reinforcing ceramic matrix composites (CMCs) because of the weavability and high temperature strength of about two to three GPa at about 1000 °C. Silicon carbide fibers have been synthesized from polycarbosilane (PCS) with ~25 μm diameter using the melt-spinning …

The Electronic And Thermodynamic Properties Of Ca Doped Lafeo3: A First Principles Study Using Density Functional Theory, Davis George Daniel

Boise State University Theses and Dissertations

Density functional theory (DFT) was used to evaluate the electronic and thermodynamic properties of Ca-doped LaFeO₃ (La_1-xCa_xFeO_3-y). La_1-xCa_xFeO_3-y exhibits ionic (O^2- anions) and electronic conductivity at high temperatures and has potential applications in gas separation, syngas production and solid oxide fuel cell cathodes. DFT is a computational technique based on the First Principles of physics, derived from the theory of quantum mechanics. DFT approximates the ground state energy of a system and can subsequently determine many bulk properties such as lattice constants, magnetic states, band gap, density …

Interfacial Interactions Between Carbon Nanoparticles And Conjugated Polymers, Yanqi Luo

Master's Theses

Conjugated polymer based electronics, a type of flexible electronic devices, can be produced from solution by traditional printing and coating processes in a roll-to-roll format such as papers and graphic films. This shows great promise for the emerging energy generation and conversion. The device performance of polymer electronics is largely dependent of crystalline structures and morphology of photoactive layers. However, the solution crystallization kinetics of conjugated polymers in the presence of electron acceptor nanoparticles has not been fully understood yet. In this study, solution crystallization kinetics of poly (3-hexylthiophene) in the presence of carbon nanotubes and graphene oxide has been …

Transport Properties Of Nano-Silica Contained Self-Consolidating Concrete, Borhan Moradi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this research study, transport properties of various self-consolidating concretes (SCCs) containing nano-particles (SiO2) were investigated. Nano-silica replaced a portion of the cementitious materials at different replacement levels ranging from 1.5 to 7.5% by weight. For the purpose of this investigation, flow, bulk, and transport properties of SCCs were studied. The investigated transport properties were absorption, water penetration, rapid chloride permeability, capillary absorption, rapid migration, and chloride diffusion. Transport properties of nano-silica SCCs were also compared to those of equivalent silica fume (micro silica) contained concretes, as well as those of control mixture (concrete without nano or micro silica).

Test …

Analytical And Experimental Analysis Of Magnetorheological Elastomers, Sarah Trabia

UNLV Theses, Dissertations, Professional Papers, and Capstones

Many engineering applications ranging from robotic joints to shock and vibration mitigation can benefit by incorporating components with variable stiffness. In addition, variable stiffness structures can provide haptic feedback (the sense of touch) to the user. In this work, it is proposed to study Magnetorheological Elastomers (MRE), where iron particles within the elastomer compound develop a dipole interaction energy, to be used in a device for haptic feedback. A novel feature of this MRE device is to introduce a field-induced variable shear modulus bias via a permanent magnet and using a current input to the electromagnetic control coil to change …

Synthesis And Characterization Of Nanoscale Polymer Films Grafted To Metal Surfaces, Yuriy Galabura

All Dissertations

Anchoring thin polymer films to metal surfaces allows us to alter, tune, and control their biocompatibility, lubrication, friction, wettability, and adhesion, while the unique properties of the underlying metallic substrates, such as magnetism and electrical conductivity, remain unaltered. This polymer/metal synergy creates significant opportunities to develop new hybrid platforms for a number of devices, actuators, and sensors. This present work focused on the synthesis and characterization of polymer layers grafted to the surface of metal objects. We report the development of a novel method for surface functionalization of arrays of high aspect ratio nickel nanowires/micronails. The polymer 'grafting to' technique …

Advanced Bulk Processing Of Lightweight Materials For Utilization In The Transportation Sector, Justin Milner

All Dissertations

The overall objective of this research is to develop the microstructure of metallic lightweight materials via multiple advanced processing techniques with potentials for industrial utilization on a large scale to meet the demands of the aerospace and automotive sectors. This work focused on (i) refining the grain structure to increase the strength, (ii) controlling the texture to increase formability and (iii) directly reducing processing/production cost of lightweight material components. Advanced processing is conducted on a bulk scale by several severe plastic deformation techniques including: accumulative roll bonding, isolated shear rolling and friction stir processing to achieve the multiple targets of …

Effect Of Silicone Finishes On The Burning Behavior Of Polyester, Julien Boyon

All Dissertations

Polyester fibers are widely used as filling in home applications such as pillows or comforters. Silicone finishes can be used to reduce friction between fibers during processing or as softeners to impart a pleasant down like hand on the fibers. However, it has been reported that these added silicone-based finishes may have a negative effect on the burning behavior of polyester. This research examined the possible mechanisms that can modify the response of polyester fibers when subjected to a flame source. In this study, a spunbond needled polyester nonwoven substrate was treated with different commercial silicone-based finishes. A vertical flame …

Effects Of Nanoholes Grown By Molecular Beam Droplet Epitaxy On Electrical Properties Of Two Dimensional Electron Gas, Yusuke Hirono

Graduate Theses and Dissertations

The effects of nanoholes, grown by molecular beam droplet epitaxy, on the electrical properties of quantum well (QW) heterostructures are reported. To investigate how the depth of nanoholes affect the electrical properties of the QW heterostructures, the growth conditions for nanoholes were optimized with respect to their depth and density. Using the results of the optimization of the nanohole growth, three InGaAs pseudomorphic quantum wells with nanoholes were investigated with varied depth and a constant density. A QW heterostructure without nanoholes was grown as a reference structure. For all the samples, temperature dependent Hall effect measurements, noise studies as a …

Finite Volume Numerical Analysis Of The Thermal Property Of Cellular Concrete Based On Two And Three Dimensional X-Ray Computerized Tomography Images, She Wei, Yang Yonggan, Xie Deqing, Zhang Yunsheng

International Conference on Durability of Concrete Structures

Cellular concrete is one kind of lightweight concrete, which are widely used in thermal insulation engineering project. In this study, a three dimensional (2D and 3D) finite-volume-based models was developed for analyzing the heat transfer mechanisms through the porous structures of cellular concretes under steady-state heat transfer condition and also for investigating the differences between 2D and 3D modeling results. 2D and 3D reconstructed pore networks were generated from the microstructural information measured by a 3D image captured by X-ray computerized tomography (X-CT). In addition, the 3D-computed value of the effective thermal conductivity was found to be in better agreement …

On Utilization Of Elliptical Rings In Assessing Cracking Tendency Of Concrete, Xiangming Zhou, Olayinka G. Oladiran, Wei Dong

International Conference on Durability of Concrete Structures

A new experimental method by utilizing elliptical rings to replace circular rings recommended by ASTM and AASHTO was explored for assessing cracking potential of concrete and other cement-based materials under restrained condition. A series of thin and thick elliptical concrete rings were tested alongside circular ones until cracking. Cracking age, position, and propagation were carefully examined. It is found that thin elliptical rings with appropriate geometry can initiate cracks quicker than circular ones, which is desirable for accelerating the ring test. However, thick elliptical rings seem not to exhibit a desirable geometry effect of accelerating ring test compared with circular …

Influence Of Controlled Permeability Formwork On The Permeability Of Concrete, Wei Lin, Q. Jiang, J. Liu, J. Liu

International Conference on Durability of Concrete Structures

Corrosion of steel reinforcement related to the intrusion of chloride ion is still the main threats to the durability of concrete structure, especially in marine environment. For the purpose of delaying the Cl⁻ concentration at the surface of steel reinforcement reaching the critical value leading to initial corrosion, the permeability of concrete is usually improved by optimizing the concrete mixture to achieve high compatibility as well as optimized pore structure. In recent years, controlled permeability formwork (CPF) which was originally developed to obtain much smoother surface of the concrete proves to promote the service performance of the concrete by …

The Correlation Of Chloride Diffusion Coefficient And Concrete Maturity Value And Its Application In Hong Kong–Zhuhai–Macao Bridge Engineering, Pengping Li, Shengnian Wang, Jianbo Xiong, Rui Chai, Yu Yan

International Conference on Durability of Concrete Structures

The correlation of chloride diffusion coefficient and concrete maturity value within 56 days of curing was investigated by the chemically combined water content method, rapid chloride migration (RCM) test, and concrete maturity test. The experimental results showed that chloride diffusion coefficient of concretes decreased not only with increasing curing ages but also with increasing curing temperature, which can promote the hydration degree of cementitous materials. There is a significant correlation between the chloride diffusion coefficient of indoor cured specimens and the concrete maturity value when expressed as a power function (R₂ = 0.976). In addition, the calculated values of …

Opto-Electronic Devices With Nanoparticles And Their Assemblies, Chieu Van Nguyen

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Nanotechnology is a fast growing field; engineering matters at the nano-meter scale. A key nanomaterial is nanoparticles (NPs). These sub-wavelength (< 100nm) particles provide tremendous possibilities due to their unique electrical, optical, and mechanical properties. Plethora of NPs with various chemical composition, size and shape has been synthesized. Clever designs of sub-wavelength structures enable observation of unusual properties of materials, and have led to new areas of research such as metamaterials. This dissertation describes two self-assemblies of gold nanoparticles, leading to an ultra-soft thin film and multi-functional single electron device at room temperature. First, the layer-by-layer self-assembly of 10nm Au nanoparticles and polyelectrolytes is shown to behave like a cellular-foam with modulus below 100 kPa. As a result, the composite thin film (~ 100nm) is 5 orders of magnitude softer than an equally thin typical polymer film. The thin film can be compressed reversibly to 60% strain. The extraordinarily low modulus and high compressibility are advantageous in pressure sensing applications. The unique mechanical properties of the composite film lead to development of an ultra-sensitive tactile imaging device capable of screening for breast cancer. On par with human finger sensitivity, the tactile device can detect a 5mm imbedded object up to 20mm below the surface with low background noise. The second device is based on a one-dimensional (1-D) self-directed self-assembly of Au NPs mediated by dielectric materials. Depending on the coverage density of the Au NPs assembly deposited on the device, electronic emission was observed at ultra-low bias of 40V, leading to low-power plasma generation in air at atmospheric pressure. Light emitted from the plasma is apparent to the naked eyes. Similarly, 1-D self-assembly of Au NPs mediated by iron oxide was fabricated and exhibits ferro-magnetic behavior. The multi-functional 1-D self-assembly of Au NPs has great potential in modern electronics such as solid state lighting, plasma-based nanoelectronics, and memory devices.

Adviser: Ravi F. Saraf

56th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 56th 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 Copper Mountain, Colorado, July 13-17, 2014.

Transparent Conducting Oxides: A Δ-Doped Superlattice Approach, Valentino R. Cooper, Sung S. Ambrose Seo, Suyoun Lee, Jun Sung Kim, Woo Seok Choi, Satoshi Okamoto, Ho Nyung Lee

Physics and Astronomy Faculty Publications

Metallic states appearing at interfaces between dissimilar insulating oxides exhibit intriguing phenomena such as superconductivity and magnetism. Despite tremendous progress in understanding their origins, very little is known about how to control the conduction pathways and the distribution of charge carriers. Using optical spectroscopic measurements and density-functional theory (DFT) simulations, we examine the effect of SrTiO3 (STO) spacer layer thickness on the optical transparency and carrier distribution in La δ-doped STO superlattices. We experimentally observe that these metallic superlattices remain highly transparent to visible light; a direct consequence of the appropriately large gap between the O 2p and Ti 3d …

Forecasting Corrosion Of Steel In Concrete Introducing Chloride Threshold Dependence On Steel Potential, Andrea Nathalie Sanchez

USF Tampa Graduate Theses and Dissertations

Corrosion initiates in reinforced concrete structures exposed to marine environments when the chloride ion concentration at the surface of an embedded steel reinforcing bar exceeds the chloride corrosion threshold (CT) value. The value of CT is generally assumed to have a conservative fixed value ranging from 0.2% to - 0.5 % of chloride ions by weight of cement. However, extensive experimental investigations confirmed that CT is not a fixed value and that the value of CT depends on many variables. Among those, the potential of passive steel embedded in concrete is a key influential factor on the value of CT …

Preparation And Characterizations Of Highly Filled Graphene-Polybenzoxazine Composites, R Plengudomkit, M Okhawilai, S Rimdusit

Journal of Metals, Materials and Minerals

In recent years, graphene has been extensively utilized in electronic applications due to its superior electrical conductivity, high thermal conductivity and excellent mechanical properties [1, 2]. This research emphasized on the development of graphene (xGnP Grade H, XG Science, USA) filled composites based on polybenzoxazine particularly at high graphene loading (0-60wt%) [3, 4]. It was found that the density of the obtained composites was linearly increased with graphene content and the values were determined to be 1.185-1.637 g/cm3 which followed the rule of mixture suggesting negligible void in the composites samples. Mechanical and thermal properties of the graphene filled polybenzoxazine …

Effects Of The Tempering On Mechanical Properties Of Dual Phase Steels, T Sirinakorn, V Uthaisangsuk, S Srimanosaowapak

Journal of Metals, Materials and Minerals

Dual Phase (DP) steels have been gradually used in the automotive industries because of their distinguished strength and ductility properties. Principally, microstructure of the DP steels contains defined amount of hard martensite islands dispersed in soft ferrite matrix. This microstructure characteristic and corresponding mechanical properties of the DP steels can be adjusted by heat treatment. In this work, effects of tempering temperature and time on tensile properties of DP steels were investigated. Continuous yielding behavior of tempered DP steels was observed up to around a temperature of 300C. At higher tempering temperature, DP steels showed distinct increased yield point. Furthermore, …

Synthesis And Characterization Of Amorphous Silica Nanoparitcles From Aqueous Silicates Uisng Cationic Surfactants, M Abou Rida, F Harb

Journal of Metals, Materials and Minerals

In this work amorphous silica was synthesized using sodium silicate and hydrochloric acid by precipitation according to St?ber method. A system of chemical reactions has been developed which permits the controlled growth of silica particles using two different cationic surfactants as the dispersing agents. These surfactants were cetyltrimethylammonium bromide [CTAB] and dodecyltrimethylammonium bromide [DTAB]. The synthesized silicas were characterized by using X-ray diffraction (XRD), Infrared Spectroscopy (IR), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and Dynamic light scattering (DLS). Addition of a dispersing agent in the reaction reduced the particle size of the silica produced. The average size of …

Corrosion Study On Low Alloy High Phosphorus Steel, B K. Jena, N Gupta, B Singh, G Sahoo

Journal of Metals, Materials and Minerals

The effect of P on corrosion behaviour of low alloy steels exposed for one month cyclic wet/dry salt spray was investigated and compared with low carbon steel. Electrochemical Impedance Spectroscopy (EIS) results revealed that the rust resistance (Rrust) increased with the number of salt spray test cycles. The higher phosphorus content steel (G12) exhibited higher rust resistance (Rrust) than that of low phosphorus content steels (SCR & G11), while similar corrosion rate was noticed from the Tafel extrapolation study in 3.5% NaCl solution for all the test samples. All steels revealed ferrite pearlite microstructure. The larger ferrite grain of G12 …

Synthesis And Characterization Of Bulk Metallic Glasses Prepared By Laser Direct Deposition, Xiaoyang Ye

Open Access Theses

Fe-based and Zr-based metallic glasses have attracted extensive interest for structural applications due to their excellent glass forming ability, superior mechanical properties, unique thermal and corrosion properties. In this study, the feasibility of synthesizing metallic glasses with good ductility by laser direct deposition is explored. Both in-situ synthesis with elemental powder mixture and ex-situ synthesis with prealloyed powder are discussed. Microstructure and properties of laser direct deposited metallic glass composites are analyzed.^ Synthesis of Fe-Cr-Mo-W-Mn-C-Si-B metallic glass composite with a large fraction of amorphous phase was accomplished using laser direct deposition. X-ray diffraction (XRD) and transmission electron microscopy investigations revealed …

Wetting And Reactivity Of Active Metal Braze Alloys On Tungsten Carbide, Hayden Peck, Alan Meier, Ph.D.

2014 Undergraduate Research

Background

Tungsten carbide is useful because of its hardness and strength. Joining of dissimilar materials especially non-metallic materials is very challenging. Active metals such as titanium can be added to a ductile filler metals such as copper to get wetting via a reduction reaction.

Conclusions

All alloy conditions wet the tungsten carbide/cobalt substrates. Two different interfacial reaction types were observed: dissolution and reduction reactions. An important issue has been identified: the braze interface reactions change the chemistry of the braze alloy which change the interaction between the braze alloy and the other material substrate.

Agronomic Benefits Of Durian Shell Biochar, N Prakongkep, R J. Gilkes, W Wiriyakitnateekul

Journal of Metals, Materials and Minerals

This study investigated the chemical properties of durian shell biochar which is used as a soil amendment. It can act as a carbon sink and as a means to improve crop yield. Plant nutrient elements in this biochar are in crystalline minerals located within the complex pore structure therefore biochar production from wastes could be a very good way to reduce demand for fertilizers. XRD and SEM-EDS results demonstrate that the numerous minerals in biochar are highly soluble, such as archerite (KH₂PO₄), chlorocalcite (KCaCl₃), kalicinite (KHCO₃), and sylvite (KCl) with small amounts …