Engineering Commons^™

Sulfur Vacancies In Photorefractive Sn2P2S6 Crystals, Eric M. Golden, Sergey A. Basun, A. A. Grabar, I. M. Stoika, Nancy C. Giles, D. R. Evans, Larry E. Halliburton

Faculty Publications

A photoinduced electron paramagnetic resonance (EPR) spectrum in single crystals of Sn2P2S6 (SPS) is assigned to an electron trapped at a sulfur vacancy. These vacancies are unintentionally present in undoped SPS crystals and are expected to play an important role in the photorefractive behavior of the material. Nonparamagnetic sulfur vacancies are formed during the initial growth of the crystal. Subsequent illumination below 100 K with 442 nm laser light easily converts these vacancies to EPR-active defects. The resulting S = 1/2 spectrum shows well-resolved and nearly isotropic hyperfine interactions with two P ions and two Sn ions. Partially resolved interactions …

Combined Effect Of Hot Extrusion And Heat Treatment On The Mechanical Behavior Of 7055 Aa Processed Via Spray Metal Forming, J. M. Schreiber, Z. R. Omcikus, Timothy Eden, Mala Sharma, V. Champagne, S. N. Patankar

Faculty Journal Articles

The mechanical properties of 7xxx series alloys can be tailored by subjecting them to deformation pro- cessing and heat treatment. In the present study dealing with spray forming of 7055 AA, extrusion and heat treatment involving solutionizing followed by peak aging resulted in improved mechanical behavior. The strength and ductility obtained are comparable to that of extruded and heat treated as-cast 7055 AA (Mondal et al., 2011) [1]. Spray forming offers an alternate route to develop high strength aluminum alloys and the current study is an attempt that draws closer to the target value of 1GPa strength and 10% ductility …

Interfacial Polymerization For Colorimetric Labeling Of Protein Expression In Cells, Jacob L. Lilly, Phillip R. Sheldon, Liv J. Hoversten, Gabriela Romero, Vivek Balasubramaniam, Brad J. Berron

Chemical and Materials Engineering Faculty Publications

Determining the location of rare proteins in cells typically requires the use of on-sample amplification. Antibody based recognition and enzymatic amplification is used to produce large amounts of visible label at the site of protein expression, but these techniques suffer from the presence of nonspecific reactivity in the biological sample and from poor spatial control over the label. Polymerization based amplification is a recently developed alternative means of creating an on-sample amplification for fluorescence applications, while not suffering from endogenous labels or loss of signal localization. This manuscript builds upon polymerization based amplification by developing a stable, archivable, and colorimetric …

Molecular-Like Hierarchical Self-Assembly Of Monolayers Of Mixtures Of Particles, P. Singh, Md. Shahadat Hossain, S. K. Gurupatham, K. Shah, E. Amah, D. Ju, M. Janjua, S. Nudurupati, I. Fischer

Publications and Research

We present a technique that uses an externally applied electric field to self-assemble monolayers of mixtures of particles into molecular-like hierarchical arrangements on fluid-liquid interfaces. The arrangements consist of composite particles (analogous to molecules) which are arranged in a pattern. The structure of a composite particle depends on factors such as the relative sizes of the particles and their polarizabilities, and the electric field intensity. If the particles sizes differ by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles form a ring around it. The number of particles …

Influence Of The Temperature On Flow-Induced Crystallization Of Isotactic Polypropylene And Propylene-Ethylene Random Copolymer, Hugo Boitout

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

When flow is applied on a semi-crystalline polymer melt, it can greatly impact how it crystallizes its final properties. Therefore, it is crucial to understand the basic mechanism of flow induced crystallization (FIC). Only then will it be possible to predict final properties from the type of resin and processing conditions. Polypropylene is one of the most widely used polymers. Its processing generally involves subjecting the melt to intense flow fields, so FIC commonly occurs.

This study investigates the influence of temperature of shear and crystallization on the FIC behavior of isotactic polypropylene (iPP). Temperature is one of the main …

Low Molecular Weight Glucosamine/L-Lactide Copolymers As Potential Carriers For The Development Of A Sustained Rifampicin Release System: Mycobacterium Smegmatis As A Tuberculosis Model, Jorge Ragusa

Department of Chemical and Biomolecular Engineering: Theses and Student Research

Tuberculosis, a highly contagious disease, ranks as the second leading cause of death from an infectious disease, and remains a major global health problem. In 2013, 9 million new cases were diagnosed and 1.5 million people died worldwide from tuberculosis. This dissertation aims at developing a new, ultrafine particle-based efficient antibiotic delivery system for the treatment of tuberculosis. The carrier material to make the rifampicin (RIF)-loaded particles is a low molecular weight star-shaped polymer produced from glucosamine (molecular core building unit) and L-lactide (GluN-LLA). Stable particles with a very high 50% drug loading capacity were made via electrohydrodynamic atomization. Prolonged …

Performance Analysis Of A Hybrid Raman Optical Parametric Amplifier In The O- And E-Bands For Cwdm Pons, Sasanthi Peiris, Nicolas Madamopoulos, Neophytos A. Antoniades, Dwight Richards, Roger Dorsinville

Publications and Research

We describe a hybrid Raman-optical parametric amplifier (HROPA) operating at the O- and E-bands and designed for coarse wavelength division multiplexed (CWDM) passive optical networks (PONs). We present the mathematical model and simulation results for the optimization of this HROPA design. Our analysis shows that separating the two amplification processes allows for optimization of each one separately, e.g., proper selection of pump optical powers and wavelengths to achieve maximum gain bandwidth and low gain ripple. Furthermore, we show that the proper design of optical filters incorporated in the HROPA architecture can suppress idlers generated during the OPA process, as well …

Microstructure And Magnetic Behavior Studies Of Processing-Controlled And Composition-Modified Fe-Ni And Mn-Al Alloys, Yunlong Geng

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

L1₀-type (Space group P4/mmm) magnetic compounds, including FeNi and MnAl, possess promising technical magnetic properties of both high magnetization and large magnetocrystalline anisotropy energy, and thus offer potential in replacing rare earth permanent magnets in some applications.

In equiatomic Fe-Ni, the disorder-order transformation from fcc structure to the L1₀ structure is a diffusional transformation, but is inhibited by the low ordering temperature. The transformation could be enhanced through the creation of vacancies. Thus, mechanical alloying was employed to generate more open-volume defects. A decrease in grain size and concomitant increase in grain boundary area resulted from …

Orientations Of Low-Energy Domain Walls In Perovskites With Oxygen Octahedral Tilts, Fei Xue, Yijia Gu, Linyun Liang, Yi Wang, Long-Qing Chen

Materials Science and Engineering Faculty Research & Creative Works

Many applications of ferroic materials, such as data storage and spintronics, are achieved through the control and manipulation of their domain wall (DW) orientations and configurations. Here we propose a rotational compatibility condition to identify low-energy DWs in perovskites with oxygen octahedral tilt instability. It is derived from the strong DW energy anisotropy arising from the rigidity and corner-sharing feature of the octahedral network. We analyze quantitatively the DWs in SrTiO₃ and explain successfully the unusual ferroelectric DW width and energy in BiFeO₃.

Slow Strain Rate Testing And Stress Corrosion Cracking Of Ultra-Fine Grained And Conventional Al–Mg Alloy, Mala M. Sharma, Josh D. Tomedi, Timothy J. Weigley

Faculty Journal Articles

Stress corrosion cracking susceptibility was investigated for an ultra-fine grained (UFG) Al–7.5Mg alloy and a conventional 5083 H111 alloy in natural seawater using slow strain rate testing (SSRT) at very slow strain rates between 1E⁻⁵ s⁻¹, 1E⁻⁶ s⁻¹ and 1E⁻⁷ s⁻¹. The UFG Al–7.5Mg alloy was produced by cryomilling, while the 5083 H111 alloy is considered as a wrought manufactured product. The response of tensile properties to strain rate was analyzed and compared. Negative strain rate sensitivity was observed for both materials in terms of the elongation to failure. However, the UFG …

An Investigation On Biocompatibility Of Bio-Absorbable Polymer Coated Magnesium Alloys, Sushma Amruthaluri

FIU Electronic Theses and Dissertations

Advances in biomaterials have enabled medical practitioners to replace diseased body parts or to assist in the healing process. In situations where a permanent biomaterial implant is used for a temporary application, additional surgeries are required to remove these implants once the healing process is complete, which increases medical costs and patient morbidity. Bio-absorbable materials dissolve and are metabolized by the body after the healing process is complete thereby negating additional surgeries for removal of implants.

Magnesium alloys as novel bio-absorbable biomaterials, have attracted great attention recently because of their good mechanical properties, biocompatibility and corrosion rate in physiological environments. …

Field-Limited Migration Of Li-Ions In Li-Ion Battery, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

The migration of Li-ions in lithium-ion battery cannot be simply described by Fick's second law; the interactions among ionic migration, field, and stress need to be taken into account when analyzing the migration of Li-ions. Using the theory of thermal activation process, the flux for ionic migration under concurrent action of electric field and mechanical stress is found to be a nonlinear function of the gradient of electric potential and the gradient of stress. Electric field can either accelerate or retard the growth of the lithiation layer, depending on polarity of the field.

Slow Release Of Ions From Internalized Silver Nanoparticles Modifies The Epidermal Growth Factor Signaling Response, Kristen K. Comfort, Elizabeth I. Maurer, Saber M. Hussain

Chemical and Materials Engineering Faculty Publications

Due to their distinctive physiochemical properties, including a robust antibacterial activity and plasmonic capability, hundreds of consumer and medical products contain colloidal silver nanoparticles (AgNPs). However, even at sub-toxic dosages, AgNPs are able to disrupt cell functionality, through a yet unknown mechanism. Moreover, internalized AgNPs have the potential to prolong this disruption, even after the removal of excess particles. In the present study, we evaluated the impact, mechanism of action, and continual effects of 50 nm AgNP exposure on epidermal growth factor (EGF) signal transduction within a human keratinocyte (HaCaT) cell line. After AgNP expose, EGF signaling was initially obstructed …

Growth And Properties Of Carbon Microcoils And Nanocoils, Muneaki Hikita, Robyn Bradford, Khalid Lafdi

Chemical and Materials Engineering Faculty Publications

Various types of coiled carbon filaments have been synthesized using chemical vapor deposition and other methods. These carbon filaments exhibit unique electrical and mechanical properties due to their versatile shapes and structures. To form coiled shapes, different types of catalyst compositions and reactive gases have been explored. Generally, coiled carbon filaments are classified by coil diameter and shape (e.g., microcoil and nanocoil). In this review, coiled carbon filaments are classified into three growth mechanism categories:

(1) bidirectional double helical growth;

(2) bidirectional twisted growth; and

(3) tip single helical or twisted growth.

Next, their synthesis methods and hypothetical growth mechanisms …

Modeling Of Thermal And Mechanical Behavior Of Zrb₂-Sic Ceramic After High Temperature Oxidation, Jun Wei, Lokeswarappa R. Dharani, K. Chandrashekhara, Greg Hilmas, William Fahrenholtz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Biphilic Nanoporous Surfaces Enabled Exceptional Drag Reduction And Capillary Evaporation Enhancement, Xianming Dai, Fanghao Yang, Ronggui Yang, Xinyu Huang, William A. Rigdon, Xiaodong Li, Chen Li

Faculty Publications

Simultaneously achieving drag reduction and capillary evaporation enhancement is highly desired but challenging because of the trade-off between two distinct hydrophobic and hydrophilic wettabilities. Here, we report a strategy to synthesize nanoscale biphilic surfaces to endow exceptional drag reduction through creating a unique slip boundary condition and fast capillary wetting by inducing nanoscopic hydrophilic areas. The biphilic nanoporous surfaces are synthesized by decorating hydrophilic functional groups on hydrophobic pristine multiwalled carbon nanotubes. We demonstrate that the carbon nanotube-enabled biphilic nanoporous surfaces lead to a 63.1% reduction of the friction coefficient, a 61.7% wetting speed improvement, and up to 158.6% enhancement …

The Stochastic Dynamics Of Tethered Microcantilevers In A Viscous Fluid, Brian A. Robbins, Milad Radiom, William A. Ducker, John Y. Walz, Mark R. Paul

Chemical and Materials Engineering Faculty Publications

We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether …

A Regression Approach For Estimation Of Anthropogenic Heat Flux Based On A Bottom-Up Air Pollutant Emission Database, Sanghyun Lee, Stuart A. Mckeen, David J. Sailor

Mechanical and Materials Engineering Faculty Publications and Presentations

A statistical regression method is presented for estimating hourly anthropogenic heat flux (AHF) using an anthropogenic pollutant emission inventory for use in mesoscale meteorological and air-quality modeling. Based on bottom-up AHF estimated from detailed energy consumption data and anthropogenic pollutant emissions of carbon monoxide (CO) and nitrogen oxides (NO_x) in the US National Emission Inventory year 2005 (NEI-2005), a robust regression relation between the AHF and the pollutant emissions is obtained for Houston. This relation is a combination of two power functions (Y = aX^b) relating CO and NO_x emissions to AHF, giving a determinant …

Passive Phase Separation Of Microgravity Bubbly Flows Using Conduit Geometry, Ryan M. Jenson, Andrew Paul Wollman, Mark M. Weislogel, Lauren Sharp, Robert Green, Peter J. Canfield, Jörg Klatte, Michael E. Dreyer

Mechanical and Materials Engineering Faculty Publications and Presentations

The ability to separate liquid and gas phases in the absence of a gravitational acceleration has proven a challenge to engineers since the inception of space exploration. Due to our singular experience with terrestrial systems, artificial body forces are often imparted in multiphase fluid systems aboard spacecraft to reproduce the buoyancy effect. This approach tends to be inefficient, adding complexity, resources, and failure modes. Ever present in multiphase phenomena, the forces of surface tension can be exploited to aid passive phase separations where performance characteristics are determined solely by geometric design and system wettability. Said systems may be readily designed …

Pump Design And Development For High Shear Grout Mixing Applications, John Kijak, David Kennedy

Conference Papers

No abstract provided.

Performance Of Columnar 7-8 Wt% Ysz Coatings On Platinum Aluminide Bondcoats, Christopher Petorak

Thermal Barrier Coatings IV

No abstract provided.

Liquid Metal Electrodes For Rechargeable Batteries, Rutooj Deshpande, Juchuan Li, Yang-Tse Cheng

Chemical and Materials Engineering Faculty Patents

An electrode for a lithium ion battery includes a liquid metal having a melting point that is below the operating temperature of the battery, which transforms from a liquid to a solid during lithiation, and wherein the liquid metal transforms from a solid to a liquid during delithiation.

Open-Source Syringe Pump Library, Bas Wijnen, Emily J. Hunt, Gerald C. Anzalone, Joshua M. Pearce

Department of Materials Science and Engineering Publications

This article explores a new open-source method for developing and manufacturing high-quality scientific equipment suitable for use in virtually any laboratory. A syringe pump was designed using freely available open-source computer aided design (CAD) software and manufactured using an open-source RepRap 3-D printer and readily available parts. The design, bill of materials and assembly instructions are globally available to anyone wishing to use them. Details are provided covering the use of the CAD software and the RepRap 3-D printer. The use of an open-source Rasberry Pi computer as a wireless control device is also illustrated. Performance of the syringe pump …

A Collagen‐Glycosaminoglycan‐Fibrin Scaffold For Heart Valve Tissue Engineering Applications, Claire Brougham, Stefan Jockenhoevel, Thomas Flanagan, Fergal O'Brien

Conference Papers

The field of heart valve biology and tissue engineering a heart valve continue to expand. The presentatio ns at this meeting reflect the advances made in both areas due to the multi-disciplinary approach taken by many laboratories.

Corrosion Resistance Of A Sand Particle-Modified Enamel Coating Applied To Smooth Steel Bars, Fujian Tang, Genda Chen, Richard K. Brow, Michael L. Koenigstein

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The protective performance of a sand particle-modified enamel coating on reinforcing steel bars was evaluated in 3.5 wt% NaCl solution by electrochemical impedance spectroscopy (EIS). Seven percentages of sand particles by weight were investigated: 0%, 5%, 10%, 20%, 30%, 50% and 70%. The phase composition of the enamel coating and sand particles were determined with the X-ray diffraction (XRD) technique. The surface and cross-sectional morphologies of the sand particle-modified enamel coating were characterized using scanning electron microscopy (SEM). XRD tests revealed three phases of sand particles: SiO₂, CaCO₃ and MgCO₃. SEM images demonstrated that the …

Humic Substances-Based Polymer System, Gerard R. Thiel

Patents (University of Northern Iowa)

A system for use in forming polymer compositions, including as a replacement for phenolic based resin systems, for instance, in preparing foundry molds. In a preferred embodiment, the system includes the use of a) a polyermizable hydroxyl-containing component comprising a humic substance (as can be provided by lignite), b) an isocyanate component, and c) a catalyst, and preferably amine catalyst, component adapted to catalyze the polymerization of a) and b). The system is optionally used as binder system in the presence of a filler, such as, in combination with a foundry aggregate such as sand. A polymer system of this …

Influence Of Crystal Structure On The Electrochemical Performance Of A-Site-Deficient Sr 1-Xnb 0.1 Co 0.9 O 3-Δ Perovskite Cathodes, Yinlong Zhu, Ye Lin, Xuan Shen, Jaka Sunarso, Wei Zhou, Shanshan Jiang, Dong Su, Fanglin Chen, Zongping Shao

Faculty Publications

The creation of A-site cation defects within a perovskite oxide can substantially alter the structure and properties of its stoichiometric analogue. In this work, we demonstrate that by vacating 2 and 5% of A-site cations from SrNb_0.1Co_0.9O_3−δ (SNC1.00) perovskites (Sr_1−sNb_0.1Co_0.9O_3−δ, s = 0.02 and 0.05; denoted as SNC0.98 and SNC0.95, respectively), a Jahn–Teller (JT) distortion with varying extents takes place, leading to the formation of a modified crystal lattice within a the perovskite framework. Electrical conductivity, electrochemical performance, chemical compatibility and microstructure of Sr …

Oxidation-Resistant, Solution-Processed Plasmonic Ni Nanochain-SioX (X < 2) Selective Solar Thermal Absorbers, Xiaobai Yu, Xiaoxin Wang, Qinglin Zhang, Juchuan Li, Jifeng Liu

Chemical and Materials Engineering Faculty Publications

Metal oxidation at high temperatures has long been a challenge in cermet solar thermal absorbers, which impedes the development of atmospherically stable, high-temperature, high-performance concentrated solar power (CSP) systems. In this work, we demonstrate solution-processed Ni nanochain-SiO_x (x < 2) and Ni nanochain-SiO₂ selective solar thermal absorbers that exhibit a strong anti-oxidation behavior up to 600 °C in air. The thermal stability is far superior to previously reported Ni nanoparticle-Al₂O₃ selective solar thermal absorbers, which readily oxidize at 450 °C. The SiO_x (x < 2) and SiO₂ matrices are derived from hydrogen silsesquioxane and tetraethyl orthosilicate precursors, respectively, which comprise Si-O cage-like …

A Non-Destructive Method For Measuring The Mechanical Properties Of Ultrathin Films Prepared By Atomic Layer Deposition, Qinglin Zhang, Xingcheng Xiao, Yang-Tse Cheng, Mark W. Verbrugge

Chemical and Materials Engineering Faculty Publications

The mechanical properties of ultrathin films synthesized by atomic layer deposition (ALD) are critical for the liability of their coated devices. However, it has been a challenge to reliably measure critical properties of ALD films due to the influence from the substrate. In this work, we use the laser acoustic wave (LAW) technique, a non-destructive method, to measure the elastic properties of ultrathin Al₂O₃ films by ALD. The measured properties are consistent with previous work using other approaches. The LAW method can be easily applied to measure the mechanical properties of various ALD thin films for multiple …

In Vitro Assessment Of Laser Sintered Bioactive Glass Scaffolds With Different Pore Geometries, Krishna C. R. Kolan, Albin Thomas, Ming-Chuan Leu, Greg Hilmas

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The pore geometry of bioactive glass scaffolds intended for use in bone repair or replacement is one of the most important parameters that could determine the rate of bone regeneration. The pore geometry would also affect the mechanical properties of the scaffolds and their rate of degradation. Scaffolds with five different architectures, having ~50% porosity, were fabricated with silicate (13–93) and borate (13–93B3) based bioactive glasses using a laser sintering process. An established, late-osteoblasts/early-osteocytes cell line was used to perform cell proliferation tests on the scaffolds. The results indicated that the cells proliferate significantly more on the scaffolds which mimic …