Engineering Commons^™

Critical Analysis On The Structural And Magnetic Properties Of Bulk And Nanocrystalline Cu-Fe-O, D. Paul Joseph, C. Venkateswaran, R. Selva Vennila

Center for Study of Matter at Extreme Conditions

Nanocrystalline and bulk samples of “Fe”-doped CuO were prepared by coprecipitation and ceramic methods. Structural and compositional analyses were performed using X-ray diffraction, SEM, and EDAX. Traces of secondary phases such as CuFe₂O₄, Fe₃O₄, and α-Fe₂O₃ having peaks very close to that of the host CuO were identified from the Rietveld profile analysis and the SAED pattern of bulk and nanocrystalline Cu_0.98Fe_0.02O samples. Vibrating Sample Magnetometer (VSM) measurements show hysteresis at 300 K for all the samples. The ferrimagnetic Neel transition temperature () was found …

College Of Engineering Senior Design Competition Fall 2010, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Processing And Composition Effects On The Fracture Behavior Of Spray-Formed 7xxx Series Al Alloys, Mala M. Sharma, Constance W. Ziemian, Timothy J. Eden

Faculty Journal Articles

The fracture properties of high-strength spray-formed Al alloys were investigated, with consideration of the effects of elemental additions such as zinc,manganese, and chromium and the influence of the addition of SiC particulate. Fracture resistance values between 13.6 and 25.6 MPa (m)^1/2 were obtained for the monolithic alloys in the T6 and T7 conditions, respectively. The alloys with SiC particulate compared well and achieved fracture resistance values between 18.7 and 25.6 MPa (m)^1/2. The spray-formed materials exhibited a loss in fracture resistance (KI) compared to ingot metallurgy 7075 alloys but had an improved
performance compared to high-solute powder …

Virtual Coatings Application System, Jason M. Ebsensberger, Michael J. Bolick, Richard J. Klein Ii, Eric C. Peterson, Chad J. Zalkin, James B. Fisher, Leslie C. Hughes

Patents (University of Northern Iowa)

A virtual coatings application system has several features to enhance the realism of simulated spray painting. The system generally includes a display screen on which is defined a virtual surface (such as a truck door) that is intended to be virtually painted or coated by the user. Alternatively, the system includes a head-mounted display unit that displays a virtual spray painting environment in which the virtual surface is defined. The user operates an instrumented spray gun controller that outputs one or more signals representing data as to the status of the controls on the spray gun controller. The system also …

Virtual Coatings Application System, Jason M. Ebensberger, Michael J. Bolick, Jeremiah G. Treloar, Richard J. Klein Ii, Eric C. Peterson, Chad J. Zalkin, James B. Fisher, Leslie C. Hughes

Patents (University of Northern Iowa)

A virtual coatings application system has several features to enhance the realism of simulated spray painting. The system generally includes a display screen on which is defined a virtual surface (such as a truck door) that is intended to be virtually painted or coated by the user. The user operates an instrumented spray gun controller that outputs one or more signals representing data as to the status of the controls on the spray gun controller. The system also has a motion tracking system that tracks the position and orientation of the spray gun controller with respect to the virtual surface …

The Relationship Between Induced Fluid Structure And Boundary Slip In Nanoscale Polymer Films, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The molecular mechanism of slip at the interface between polymer melts and weakly attractive smooth surfaces is investigated using molecular dynamics simulations. In agreement with our previous studies on slip flow of shear-thinning fluids, it is shown that the slip length passes through a local minimum at low shear rates and then increases rapidly at higher shear rates. We found that at sufficiently high shear rates, the slip flow over atomically flat crystalline surfaces is anisotropic. It is demonstrated numerically that the friction coefficient at the liquid-solid interface (the ratio of viscosity and slip length) undergoes a transition from a …

Synthesis Of Mild–Hard Aao Templates For Studying Magnetic Interactions Between Metal Nanowires, Jin-Hee Lim, Aurelian Rotaru, Seong-Gi Min, Leszek Malkinski, John B. Wiley

Physics Faculty Publications

The sequential application of mild and hard anodization techniques in the fabrication of porous aluminamembranes allows one to decrease the number of continuous pores in anodized aluminium oxide (AAO) templates. Initially, standard mild anodization techniques were used to create porous templates with 100 nm interpore distances and 70 nm pore diameters. Hard anodization treatment on the same membrane then produced interpore distances of about 265 nm with diameters of 110 nm. At the interface between the two anodization steps, many of the mild-side pores were terminated to create a mild–hard membrane (Mi–Ha AAO) where the functional interpore distances were 200–300 …

Structures Of Human Thymidylate Synthase R163k With Dump, Fdump And Glutathione Show Asymmetric Ligand Binding, Lydia M. Gibson, Lesa R. Celeste, Leslie L. Lovelace, Lukasz Lebioda

Faculty Publications

Thymidylate synthase (TS) is a well validated target in cancer chemotherapy. Here, a new crystal form of the R163K variant of human TS (hTS) with five subunits per asymmetric part of the unit cell, all with loop 181-197 in the active conformation, is reported. This form allows binding studies by soaking crystals in artificial mother liquors containing ligands that bind in the active site. Using this approach, crystal structures of hTS complexes with FdUMP and dUMP were obtained, indicating that this form should facilitate high-throughput analysis of hTS complexes with drug candidates. Crystal soaking experiments using oxidized glutathione revealed that …

Virtual Blasting System For Removal Of Coating And/Or Rust From A Virtual Surface, Michael Bolick, Chris Lampe, Jason Ebensberger, Jeremiah Treloar, Rick Klein, Eric Conrad Peterson, Chad Jason Zalkin

Patents (University of Northern Iowa)

A computer simulation and virtual reality system simulates the use of a blasting nozzle to remove one or more coatings and/or rust from a virtual surface. The user operates an electronic controller in the form of a blasting nozzle that outputs a signal indicating whether the blasting nozzle controller is in an "on" position or in an "off" position. The system also has a motion tracking system that tracks the position and orientation of the blasting nozzle controller with respect to the virtual surface defined on the display screen. Simulation software in a computer generates virtual blast pattern data, and …

Measurement And Modeling Of Infrared Nonlinear Absorption Coefficients And Laser-Induced Damage Thresholds In Ge And Gasb, Torrey J. Wagner, Matthew J. Bohn, Ronald A. Coutu Jr., L. P. Gonzales, J. M. Murray, K. L. Schepler, S. Guha

Faculty Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 µm for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 µm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond …

Thermodynamics Of Strained Vanadium Dioxide Single Crystals, Yijia Gu, Jinbo Cao, Junqiao Wu, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Vanadium dioxide undergoes a metal-insulator transition, in which the strain condition plays an important role. To investigate the strain contribution, a phenomenological thermodynamic potential for the vanadium dioxide single crystal was constructed. The transformations under the uniaxial stress, wire, and thin film boundary conditions were analyzed, and the corresponding phase diagrams were constructed. The calculated phase diagrams agree well with existing experimental data, and show that the transformation temperature (and Curie temperature) strongly depends on the strain condition.

Programmable Periodicity Of Quantum Dot Arrays With Dna Origami Nanotubes, Hieu Bui, Craig Onodera, Carson Kidwell, Yerpeng Tan, Elton Graugnard, Wan Kuang, Jeunghoon Lee, William B. Knowlton, Bernard Yurke, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

To fabricate quantum dot arrays with programmable periodicity, functionalized DNA origami nanotubes were developed. Selected DNA staple strands were biotin-labeled to form periodic binding sites for streptavidin-conjugated quantum dots. Successful formation of arrays with periods of 43 and 71 nm demonstrates precise, programmable, large-scale nanoparticle patterning; however, limitations in array periodicity were also observed. Statistical analysis of AFM images revealed evidence for steric hindrance or site bridging that limited the minimum array periodicity.

Coated Steel Rebar For Enhanced Concrete-Steel Bond Strength And Corrosion Resistance, Genda Chen, Jeffery S. Volz, Richard K. Brow, Dongming Yan, Signo Tadeu Dos Reis, Chenglin Wu, Fujian Tang, Charles R. Werner, Xing Tao

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This report summarizes the findings and recommendations on the use of enamel coating in reinforced concrete structures both for bond strength and corrosion resistance of steel rebar. Extensive laboratory tests were conducted to characterize the properties of one- and two-layer enamel coatings. Pseudostatic tests were performed with pullout, beam and column specimens to characterize mechanical properties and develop design equations for the development length of steel rebar in lap splice and anchorage areas. The splice length equation was validated with the testing of large-scale columns under cyclic loading. For corrosion properties, ponding, salt spray, accelerated corrosion, potentiodynamic and electrochemical impedance …

Kinetics Of Dna And Rna Hybridization In Serum And Serum-Sds, Elton Graugnard, Amber Cox, Jeunghoon Lee, Cheryl Jorcyk, Bernard Yurke, William L. Hughes

Materials Science and Engineering Faculty Publications and Presentations

Cancer is recognized as a serious health challenge both in the United States and throughout the world. While early detection and diagnosis of cancer leads to decreased mortality rates, current screening methods require significant time and costly equipment. Recently, increased levels of certain micro-ribonucleic acids (miRNAs) in the blood have been linked to the presence of cancer. While blood-based biomarkers have been used for years in cancer detection, studies analyzing trace amounts of miRNAs in blood and serum samples are just the beginning. Recent developments in deoxyribonucleic acid (DNA) nanotechnology and DNA computing have shown that it is possible to …

The Electronic Structure And Secondary Pyroelectric Properties Of Lithium Tetraborate, Volodymyr T. Adamiv, Yaroslav V. Burak, David J. Wooten, John W. Mcclory, James C. Petrosky, Ihor Ketsman, Ya B. Losovyj, Peter A. Dowben, Jie Xiao

Faculty Publications

We review the pyroelectric properties and electronic structure of Li₂B₄O₇(110) and Li₂B₄O₇(100) surfaces. There is evidence for a pyroelectric current along the [110] direction of stoichiometric Li₂B₄O₇ so that the pyroelectric coefficient is nonzero but roughly 10³ smaller than along the [001] direction of spontaneous polarization. Abrupt decreases in the pyroelectric coefficient along the [110] direction can be correlated with anomalies in the elastic stiffness contributing to the concept that the pyroelectric coefficient is not simply a vector but has qualities of …

Manipulation Of Suspended Single Cells By Microfluidics And Optical Tweezers, Nathalie Neve De Mevergnies, Sean S. Kohles, Shelley R. Winn, Derek C. Tretheway

Mechanical and Materials Engineering Faculty Publications and Presentations

Chondrocytes and osteoblasts experience multiple stresses in vivo. The optimum mechanical conditions for cell health are not fully understood. This paper describes the optical and microfluidic mechanical manipulation of single suspended cells enabled by the μPIVOT, an integrated micron resolution particle image velocimeter (μPIV) and dual optical tweezers instrument (OT). In this study, we examine the viability and trap stiffness of cartilage cells, identify the maximum fluid-induced stresses possible in uniform and extensional flows, and compare the deformation characteristics of bone and muscle cells. These results indicate cell photodamage of chondrocytes is negligible for at least 20 min for laser …

Ebc Development For Hot-Pressed Y2O3/Al2O3 Doped Silicon Nitride Ceramics, Sivakumar Ramasamy, Surendra N. Tewari, Kang N. Lee, Ramakrishna T. Bhatt, Dennis S. Fox

Chemical & Biomedical Engineering Faculty Publications

Multilayer EBCs of alcohol and sol-based slurries containing (a) 45% SiO₂-34% Y₂O₃-%Al₂O₃, (b) mullite/Gd₂SiO₅ (88/12wt.%) with and without B₂O₃ addition, (c) mullite/rare-earth silicates (94/6wt.%, (Gd₂SiO₅, Lu₂SiO₅, Er₂SiO₅, and HfSiO₄)), and (d) only mullite, were applied on hot pressed Y₂O₃/Al₂O₃ doped Si₃N₄ substrates. Of the four major EBC systems studied, only mullite/Gd₂SiO₅ (88/12wt.%) EBCs sintered in air at …

Nanofibers And Nanoparticles From The Insect-Capturing Adhesive Of The Sundew (Drosera) For Cell Attachment, Mingjun Zhang, Scott C. Lenaghan, Lijin Xia, Lixin Dong, Wei He, William R. Henson, Xudong Fan

Faculty Publications and Other Works -- Mechanical, Aerospace and Biomedical Engineering

Background

The search for naturally occurring nanocomposites with diverse properties for tissue engineering has been a major interest for biomaterial research. In this study, we investigated a nanofiber and nanoparticle based nanocomposite secreted from an insect-capturing plant, the Sundew, for cell attachment. The adhesive nanocomposite has demonstrated high biocompatibility and is ready to be used with minimal preparation.

Results

Atomic force microscopy (AFM) conducted on the adhesive from three species of Sundew found that a network of nanofibers and nanoparticles with various sizes existed independent of the coated surface. AFM and light microscopy confirmed that the pattern of nanofibers corresponded …

Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day

Materials Science and Engineering Faculty Research & Creative Works

There is an increasing demand for synthetic scaffolds with the requisite biocompatibility, internal architecture, and mechanical properties for the bone repair and regeneration. In this work, scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication (FEF) method and evaluated in vitro for potential applications in bone repair and regeneration. The process parameters for FEF production of scaffolds with the requisite microstructural characteristics, as well as the mechanical and cell culture response of the scaffolds were evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a dense glass network with interpenetrating …

Optimization Of Selective Laser Sintering Process For Fabrication Of Zirconium Diboride Parts, Ming-Chuan Leu, Shashwatashish Pattnaik, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Selective Laser Sintering (SLS) was investigated to fabricate Zirconium Diboride (ZrB₂) parts for ultra-high temperature applications. Experiments were conducted to determine values of SLS process parameters (laser power, scan speed, line spacing, and layer thickness) that can be used to build ZrB₂ parts with high integrity and sharp geometrical features. A sacrificial plate with a proper number of layers (determined from experimentation) separated from the main part was built in order to reduce thermal gradients when building the main part. The sacrificial plate was found to assist in eliminating cracks in the bottom of the main part. …

Selective Laser Sintering Of 13-93 Bioactive Glass, Krishna C. R. Kolan, Ming-Chuan Leu, Greg Hilmas, Mariano Garcia Velez

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Bioactive glasses are more promising than biopolymers in fabricating scaffolds for bone tissue repair because they convert to hydroxyapatite, when implanted in vivo. Both direct and indirect selective laser sintering (SLS) methods of 13-93 bioactive glass were considered in this research to study the feasibility of fabricating scaffolds for bone repair applications. Stearic acid was used as the binder in the indirect method to fabricate the scaffolds. The green scaffolds underwent binder burnout and sintering at various soaking conditions between 675⁰C and 700⁰C, achieving a maximum compressive strength of 23.6 MPa, which is higher than that of the human cancellous …

Computer Aided Contour Profiling Of High Strength Deposits, Sriram Praneeth Isanaka, Amar Bala Sridhar, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufacturing processes suffer from the effect of ripples, edge rounding and surface variations. To reduce their effect, ideal process parameters for the laser deposition process were investigated. Also, a new method was identified to analyze deposits by accurately plotting their contours. This was achieved through point cloud data of the deposits generated using coordinate measurement and 3D scanning. Curve fitting was performed on the data in Matlab to generate the contours of the deposit. The intercept values, heights, and contact angle of the curves give an indication of the uniformity of deposits and aid in reducing defects.

Metallurgy In The Roman Forts Of Scotland: An Archaeological Analysis, Scott S. Stetkiewicz

Honors Projects

Investigates the presence of metalworking in thirty-seven Roman forts in Scotland during the Flavian, Antonine, and Severan occupations largely through analysis of published documentation concerning relevant archaeological excavations.

Processing And Characterization Of New Oxy-Sulfo-Telluride Glasses In The Ge-Sb-Te-S-O System, C. (Charmayne) Smith (Lonergan), J. Jackson, L. Petit, C. Rivero-Baleine, K. Richardson

Materials Science and Engineering Faculty Research & Creative Works

New oxy-sulfo-telluride glasses have been prepared in the GeSbTeSO system employing a two-step melting process which involves the processing of a chalcogenide glass (ChG) and subsequent melting with TeO₂ or Sb₂O₃. The progressive incorporation of O at the expense of S was found to increase the density and the glass transition temperature and to decrease the molar volume of the investigated oxy-sulfo-telluride glasses. We also observed a shift of the visNIR cut-off wavelength to longer wavelength probably due to changes in Sb coordination within the glass matrix and overall matrix polarizability. Using Raman spectroscopy, correlations …

Structural And Magnetic Properties Of Neodymium - Iron - Boron Clusters, Jeremy J. Anderson

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

Using inert gas condensation techniques the properties of sputtered neodymium-iron-born clusters were investigated. A D.C. magnetron sputtering source created vaporous Nd-Fe-B which was then condensed into clusters and deposited onto silicon substrates. A composite target of Nd-Fe-B discs on an iron plate and a composite target of Nd-(Fe-Co)-B were utilized to create clusters. The clusters were coated with a carbon layer through R.F. sputtering to prevent oxidation.

Samples were investigated in the TEM and showed a size distribution with an average particle diameter of 8.11 nm. The clusters, upon deposition, were amorphous as indicated by diffuse diffraction patterns obtained through …

Comprehensive Process Maps For Synthesizing High Density Aluminum Oxide-Carbon Nanotube Coatings By Plasma Spraying For Improved Mechanical And Wear Properties, Anup K. Keshri

FIU Electronic Theses and Dissertations

Plasma sprayed aluminum oxide ceramic coating is widely used due to its outstanding wear, corrosion, and thermal shock resistance. But porosity is the integral feature in the plasma sprayed coating which exponentially degrades its properties. In this study, process maps were developed to obtain Al2O3-CNT composite coatings with the highest density (i.e. lowest porosity) and improved mechanical and wear properties. Process map is defined as a set of relationships that correlates large number of plasma processing parameters to the coating properties. Carbon nanotubes (CNTs) were added as reinforcement to Al2O3 coating to improve the fracture toughness and wear resistance. Two …

Boron Carbide Based Solid State Neutron Detectors: The Effects Of Bias And Time Constant On Detection Efficiency, Nina Hong, John Mullins, Keith Foreman, Shireen Adenwalla

Shireen Adenwalla Papers

Neutron detection in thick boron carbide(BC)/n-type Si heterojunction diodes shows a threefold increase in efficiency with applied bias and longer time constants. The improved efficiencies resulting from long time constants have been conclusively linked to the much longer charge collection times in the BC layer. Neutron detection signals from both the p-type BC layer and the n-type Si side of the heterojunction diode are observed, with comparable efficiencies. Collectively, these provide strong evidence that the semiconducting BC layer plays an active role in neutron detection, both in neutron capture and in charge generation and collection.

Limitations Of Poole–Frenkel Conduction In Bilayer Hfo2/Sio2 Mos Devices, Richard G. Southwick Iii, Justin Reed, Christopher Buu, Ross Butler, Gennadi Bersuker, William B. Knowlton

Materials Science and Engineering Faculty Publications and Presentations

The gate leakage current of metal–oxide– semiconductors (MOSs) composed of hafnium oxide (HfO₂) exhibits temperature dependence, which is usually attributed to the standard Poole–Frenkel (P–F) transport model. However, the reported magnitudes of the trap barrier height vary significantly. This paper explores the fundamental challenges associated with applying the P–F model to describe transport in HfO₂/SiO₂ bilayers in n/p MOS field-effect transistors composed of 3- and 5-nm HfO₂ on 1.1-nm SiO₂ dielectric stacks. The extracted P–F trap barrier height is shown to be dependent on several variables including the following: the temperature range, method …

Standardization Of A Volumetric Displacement Measurement For Two-Body Abrasion Scratch Test Data Analysis, Ryan L. Kobrick, David M. Klaus, Kenneth W. Street Jr.

Publications

A limitation has been identified in the existing test standards used for making controlled, two-body abrasion scratch measurements based solely on the width of the resultant score on the surface of the material. A new, more robust method is proposed for analyzing a surface scratch that takes into account the full three-dimensional profile of the displaced material. To accomplish this, a set of four volume displacement metrics are systematically defined by normalizing the overall surface profile to statistically denote the area of relevance, termed the “Zone of Interaction” (ZOI). From this baseline, depth of the trough and height of the …

Recent Advances In High Density Area Array Interconnect Bonding For 3d Integration, J. M. Lannon, J., C. Gregory, M. Lueck, A. Huffman, D. Temple, Amy J. Moll, William B. Knowlton

Materials Science and Engineering Faculty Publications and Presentations

The demand for more complex and multifunctional micro systems with enhanced performance characteristics for military applications is driving the electronics industry toward the use of best-of-breed materials and device technologies. Threedimensional (3-D) integration provides a way to build complex microsystems through bonding and interconnection of individually optimized device layers without compromising system performance and fabrication yield. Bonding of device layers can be achieved through polymer bonding or metal-metal interconnect bonding with a number of metalmetal systems. RTI has been investigating and characterizing Cu-Cu and CulSn-Cu processes for high density area array imaging applications, demonstrating high yield bonding between sub-I5 11m …