Materials Science and Engineering Commons^™

Radiographic Density Of Selected Materials At Different Thicknesses, Thien Quang Vu-Nguyen, Bernice Mills

STAR Program Research Presentations

X-rays are widely used in medicine and materials science to identify impurities or fractures within the target object. In material science, x-rays can be used to identify the thickness of samples with different material densities. The current method is to collect a radiograph using estimated conditions, evaluate the results, then make changes to the conditions. The residual image can be rescanned making it possible to obtain an image of lower radiographic density. By tabulating or graphing the effects of energy changes and rescans, a more informed choice of conditions is possible.

For this study, six materials were chosen with a …

Radiographic Density Of Selected Materials At Different Thicknesses, Thien Quang Vu-Nguyen, Bernice Mills

STAR Program Research Presentations

X-rays are widely used in medicine and materials science to identify impurities or fractures within the target object. In material science, x-rays can be used to identify the thickness of samples with different material densities. The current method is to collect a radiograph using estimated conditions, evaluate the results, then make changes to the conditions. The residual image can be rescanned making it possible to obtain an image of lower radiographic density. By tabulating or graphing the effects of energy changes and rescans, a more informed choice of conditions is possible.

For this study, six materials were chosen with a …

Oxidized Phospholipids Regulation Of The Monocyte Recruitment Parthway In Human Aortic Endothelial Cells, Piao Jian Tan

Masters Theses

Low-density lipoprotein particles in blood plasma invade the endothelium and become oxidized, creating risk of CHD associated with atherosclerosis, the main underlying condition in coronary heart disease. Oxidation products of the phospholipid 1-palmitoyl- 2-arachidonoyl-sn-glycerol-3-phosphatidylcholine (PAPC) are bioactive components of minimally oxidized LDL that stimulate endothelial cells that line the artery, leading to monocyte binding and atherosclerosis. It is hypothesized that the regulation of the monocyte recruitment pathway by these oxidized phospholipids is mediated by the binding of OxPAPC to one or more mediating proteins. Human recombinant VEGFR2, GRP78, and EP2bind to OxPNB, a biotinylated analog of OxPAPC, demonstrated using Western …

Wet Chemical Synthesis And Characterization Of Nanomaterials For Solar Cell Applications, Krystle N. Sy, Ramprasad Gandhiraman, Jessica E. Koehne

STAR Program Research Presentations

During long term space missions, it is necessary to have a reliable source of energy. Solar cells are an easy and reliable way to convert energy from the sun to electrical energy. NASA has used solar cells manufactured on Earth as an energy source for many of its missions. In order to develop technologies that will enable high efficiency solar cells, we are synthesizing nanostructured materials. A range of nanostructured materials, such as titanium dioxide nanowires, nickel nanoparticles, copper nanoparticles, and silver nanoparticles/nanowires, are synthesized. In this work, we are reporting on the synthesis of these nanomaterials and the electron …

Structure And Optical Properties Of Transition Metal Dichalcogenides (Tmds) – Mx2 (M = Mo, W & X = S, Se) Under High Pressure And High Temperature Conditions, Nirup Reddy Bandaru

UNLV Theses, Dissertations, Professional Papers, and Capstones

Layered structured materials such as transition metal dichalcogenides (TMDs) have gained immense interest in recent times due to their exceptional structural, electrical and optical properties. Recent studies show semiconducting TMDs such as MX₂ (M= Mo, W & X = S, Se) could be used as potential shock absorbing material, which has resulted in extensive studies on structural stability of these materials under the influence of high pressure. Understanding the structural stability of transition metal dichalcogenides (TMDs) such as MoS2, MoSe2, WS2, and WSe2 under high pressure has been very challenging due to contradicting observations and interpretations reported in the …

Feasibility Study Of Custom Manufacturing Of Ionic Polymer-Metal Composite Sensors, Shelby E. Nelson

UNLV Theses, Dissertations, Professional Papers, and Capstones

The ability to create an ion exchange membrane with any shape or thickness through custom manufacturing techniques is highly desirable in ionic polymer-metal composite (IPMC) research. This is caused by the poor selection and limited availability of certain thicknesses of commercial ion exchange membranes. The objective of this study is to determine the feasibility of manufacturing custom ion exchange membranes for IPMC sensors. The manufacturing methods used in this study are extrusion, injection molding, and hot pressing. A commercial membrane from Golden Energy Fuel Cells (GEFC) is used as a comparison. After the membranes are fabricated, certain properties of the …

Morphology-Property Relationship For Binary Organic Thin Films, Alyssa Lynn Griffin

Master's Theses

Organic thin films can be readily mass-produced through solution-based fabrication methods including ink-printing and solution-casting because their light weight, flexibility, and inexpensive sources. Their applications range from organic field-effect transistors (OFET), organic solar cells (OSC), to organic light emitting diodes (OLEDs). Compared with pure component films, binary organic thin films (BOTF) allows for novel characteristics and specialized features to handle more demanding tasks. Due to the complex intermolecular interactions in BOTF, various microscopic phases with different morphological and electronic properties may be formed and this information is difficult to extract through conventional bulk measurements.

Organic thin films can be readily …

Fundamental Problems In Porous Materials: Experiments And Computer Simulation, Zhanping Xu

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

Porous materials have attracted massive scientific and technological interest because of their extremely high surface-to-volume ratio, molecular tunability in construction, and surface-based applications. Through my PhD work, porous materials were engineered to meet the design in selective binding, self-healing, and energy damping. For example, crystalline MOFs with pore size spanning from a few angstroms to a couple of nanometers were chemically engineered to show 120 times more efficiency in binding of large molecules. In addition, we found building blocks released from those crystals can be further patched back through a healing process at ambient and low temperatures down to -56 …

Efficiency Enhancement In Solution Processed Organic And Organic–Inorganic Hybrid Perovskite Solar Cells, Zhengguo Xiao

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

Solution processed thin film photovoltaic devices are one of the most promising renewable energy sources. Organic solar cells have been intensively studied due to their advantages of light-weight, flexibility and low-cost materials and manufacturing. The organic-inorganic hybrid perovskite materials have recently shown great potential application in solar cells. The PCE increased dramatically from 3.8% in 2009 to a certified efficiency of 20.1% in 2014. In this dissertation, we focus on the efficiency enhancement for solution processed organic and organic-inorganic solar cells.

In Chapter 2, I demonstrated that the crystallinity of the ferroelectric polymer P(VDF-TrFE) at the organic active layer/ electrode …

Mechanical Properties Of Laser-Sintered-Nylon Diamond Lattices, Clayton Neff

USF Tampa Graduate Theses and Dissertations

Additive manufacturing offers a manufacturing technique to produce complex geometry prototypes at a rapid pace and low cost. These advantages advocate additive manufacturing for the design and production of cellular structures. Cellular structures are interesting because they contain a large amount of porosity (void space of air) to manifest a lightweight structure. Designs of cellular structures generate a periodic pattern; often of complex geometry, called a lattice.

There has been a significant amount of research to maximize specific stiffness of lattice structures but little to evaluate low-stiffness lattices. Low-stiffness structures benefit energy absorbance through bending of the lattice. This research …

Effects Of Target Composition On The Optical Constants Of Dc Sputtered Zno:Al Thin Films, B. Samwel, M. E. Samiji, N.R. Mlyuka

Tanzania Journal of Science

Al-doped ZnO thin films were deposited from ZnO:Al ceramic and Zn:Al metal alloy targets in Ar and Ar + O2 atmospheres respectively, using Direct Current (DC) magnetron sputtering. The samples exhibited transmittance T > 80% in visible region with good NIR shielding.  The results indicated that, band gap energy ranged from 3.34 to 3.44 eV and 3.39 to 3.46 eV for films prepared from alloy and ceramic targets, respectively. Films obtained from alloy target at a substrate temperature of 200 oC showed low electrical sheet resistance of 10 Ω/sq, and highest values of mobility (15.9 cm2/Vs) and carrier concentration (2.98 × …

Electrode Side Reactions, Capacity Loss And Mechanical Degradation In Lithium-Ion Batteries, Jiagang Xu, Rutooj D. Deshpande, Jie Pan, Yang-Tse Cheng, Vincent S. Battaglia

Chemical and Materials Engineering Faculty Publications

For advancing lithium-ion battery (LIB) technologies, a detailed understanding of battery degradation mechanisms is important. In this article, experimental observations are provided to elucidate the relation between side reactions, mechanical degradation, and capacity loss in LIBs. Graphite/Li(Ni_1/3Mn_1/3Co_1/3)O₂ cells of two very different initial anode/cathode capacity ratios (R, both R > 1) are assembled to investigate the electrochemical behavior. The initial charge capacity of the cathode is observed to be affected by the anode loading, indicating that the electrolyte reactions on the anode affect the electrolyte reactions on the cathode. Additionally, the rate of “marching” …

A Quantitative Perspective On Surface Marker Selection For The Isolation Of Functional Tumor Cells, Calvin F. Cahall, Jacob L. Lilly, Edward A. Hirschowitz, Brad J. Berron

Chemical and Materials Engineering Faculty Publications

Much effort has gone into developing fluid biopsies of patient peripheral blood for the monitoring of metastatic cancers. One common approach is to isolate and analyze tumor cells in the peripheral blood. Widespread clinical implementation of this approach has been hindered by the current choice of targeting epithelial markers known to be highly variable in primary tumor sites. Here, we review current antigen-based tumor cell isolation strategies and offer biological context for commonly studied cancer surface markers. Expression levels of the most common markers are quantitated for three breast cancer and two non-small cell lung cancer (NSCLC) lineage models. These …

57th Annual Rocky Mountain Conference On Magnetic Resonance

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 57th 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 Snowbird, Utah, July 26-31, 2015.

Improved Terahertz Modulation Using Germanium Telluride (Gete) Chalcogenide Thin Films, Alexander H. Gwin, Christopher H. Kodama, Tod V. Laurvick, Ronald Coutu Jr., Philip F. Taday

Faculty Publications

We demonstrate improved terahertz (THz) modulation using thermally crystallized germanium telluride (GeTe) thin films. GeTe is a chalcogenide material that exhibits a nonvolatile, amorphous to crystalline phase change at approximately 200 °C, as well as six orders of magnitude decreased electrical resistivity. In this study, amorphous GeTe thin films were sputtered on sapphire substrates and then tested using THz time-domain spectroscopy (THz-TDS). The test samples, heated in-situ while collecting THz-TDS measurements, exhibited a gradual absorbance increase, an abrupt nonvolatile reduction at the transition temperature, followed by another gradual increase in absorbance. The transition temperature was verified by conducting similar thermal …

Spotlight On Graphene Research From The Middle East, Kathleen A. Lehman

University Libraries Faculty Publications and Presentations

In an extension to the 2011 article “Reviews of Science for Science Librarians: Graphene” (Lehman 2011), this paper seeks to continue exploring the trend of graphene research but limits its focus to the research production of countries in the Middle East. In addition to reporting on the research output of this group of countries, this article will also examine the most prolific Middle Eastern graphene authors,their supporting institutions and funding agencies, the most cited publications from this group, the journals most used for publication of their work, and the general trend in graphene research growth in the Middle East. As …

Development Of A National Anthropogenic Heating Database With An Extrapolation For International Cities, David J. Sailor, Matei Georgescu, Jeffrey M. Milne, Melissa A. Hart

Mechanical and Materials Engineering Faculty Publications and Presentations

Given increasing utility of numerical models to examine urban impacts on meteorology and climate, there exists an urgent need for accurate representation of seasonally and diurnally varying anthropogenic heating data, an important component of the urban energy budget for cities across the world. Incorporation of anthropogenic heating data as inputs to existing climate modeling systems has direct societal implications ranging from improved prediction of energy demand to health assessment, but such data are lacking for most cities. To address this deficiency we have applied a standardized procedure to develop a national database of seasonally and diurnally varying anthropogenic heating profiles …

Lignopolymers As Viscosity-Reducing Additives In Magnesium Oxide Suspensions, Lisa R. Murray, Chetali Gupta, Newell R. Washburn, Kendra Erk

School of Materials Engineering Faculty Publications

Lignopolymers are a new class of polymer additives with the capability to be used as dispersants in cementitious pastes. Made with kraft lignin cores and grafted polymer side- chains, the custom-synthesized lignopolymers were examined in terms of the molecular architecture for viscosity reducing potential in inert model suspensions. Lignin-poly(acrylic acid) (LPAA) and lignin-polyacrylamide (LPAm) have been found to vary the rheology of magnesium oxide (MgO) suspensions based on differences in chain architecture and particle- polymer interactions. A commercial comb-polymer polycarboxylate ester was compared to LPAA and LPAm at 2.7 mg/mL, a typical dosage for cement admixtures, as well as 0.25 …

Impurity Diffusion As A Possible Metal Chronometer For Pre-Detonation Nuclear Forensics, Edward T. Peskie, Howard L. Hall

International Journal of Nuclear Security

The ability to determine the age of seized nuclear material—that is, the time that has passed since it was formed— would provide crucial data to be used in its investigation. This paper reviews the methods and mathematical reasoning behind the use of diffusion theory, as previously applied to analysis of metals in ancient artifacts and other objects, to modern investigations in nuclear science. We here examine the time-dependent processes of diffusion, including grain boundary diffusion and discontinuous precipitation, and we assess the utility of examining the profiles of impurity and alloying element concentrations for use as a tool in pre-detonation …

Radiation Damage As A Possible Metal Chronometer For Pre-Detonation Nuclear Forensics, Edward T. Peskie, Howard L. Hall

International Journal of Nuclear Security

The better we can determine how long ago nuclear material was made, the sharper our tools for investigating seized nuclear materials. This paper examines the effects of radiation damage caused by the decay of uranium isotopes, and assesses how experts in nuclear forensics could use the analyses of these damaged regions to determine how much time has passed since metal samples were formed. It also draws parallels from fission track dating studies of mineral samples under geologic time, and proposes modifications to past publications on α-recoil track dating in order to determine the time since a metal sample was cast …