Chemical Engineering Commons^™

Novel Routes For Synthesis Of Pd Nanoparticles And Faceted Zno Supports For Heterogeneous Catalysts, Patrick David Burton

Chemical and Biological Engineering ETDs

Alcohol steam reforming is a promising source of hydrogen as fuel, and could be improved by the use of an optimal catalyst. The methanol steam reforming reaction, CH3OH+H2O --> 3H2+CO2 frequently conducted by means of a Cu/ZnO catalyst. Unfortunately, this catalyst deactivates quickly and is pyrophoric. Pd catalysts are much more stable, but reactions using these catalyst follow the decomposition pathway, CH3OH --> 2H2+CO. PdZn alloys can achieve the desired selectivity, and have been noted to form under reaction conditions from Pd/ZnO heterogeneous catalysts. In the present work, careful synthesis techniques of specific support and nanoparticle surfaces have been developed …

Effects Of Non-Planar Distortions In Porphyrin Compounds On Their Properties And Functionality, Raid Haddad

Chemical and Biological Engineering ETDs

Porphyrins and related compounds are ubiquitous in nature, performing diverse functions including solar energy transduction, electron transport, molecular transport and storage, and catalysis. Due to their unique photophysical and chemical properties, they are excellent candidates for application as photosensitizers, catalysts, photocatalysts, molecular electronics and opto-electronics. Several properties of porphyrins are sensitive to small variations in their structure, and this dissertation investigates the effects of out-of-plane distortions of the macrocycle on optical properties, reactivity to axial ligands, and substituent rotation. The structure-functions relationships are examined using molecular simulations, UV-visible absorption spectroscopy, resonance Raman spectroscopy, and normal-coordinate structural decomposition (NSD) analysis of …

Polymerization In Emulsion Microdroplet Reactors, Nick J. Carroll

Chemical and Biological Engineering ETDs

The goal of this research project is to utilize emulsion droplets as chemical reactors for execution of complex polymerization chemistries to develop unique and functional particle materials. Emulsions are dispersions of immiscible fluids where one fluid usually exists in the form of drops. Not surprisingly, if a liquid-to-solid chemical reaction proceeds to completion within these drops, the resultant solid particles will possess the shape and relative size distribution of the drops. The two immiscible liquid phases required for emulsion polymerization provide unique and complex chemical and physical environments suitable for the engineering of novel materials. The development of novel non-ionic …

Electrochemical Performance Of Tin Dioxide/Carbon Xerogel Composites As Anode Materials For Lithium-Ion Batteries, Xiao-Jing Liu, Lin-Lin Qin, Yi-Ning Shi, Ming-Sen Zheng, Quan-Feng Dong

Journal of Electrochemistry

The tin dioxide/carbon xerogel composites were synthesized by using vacuum infiltration method. Structural characterization and morphology of the composites were investigated by using XRD, TEM and SEM techniques. BET test was performed to determine the pore size distributions of carbon xerogels and the composites. The results showed that the nano-sized SnO₂ particles (5~10 nm) were encapsulated in the pores of carbon xerogels. During the electrochemical tests the SnO₂ in the composites exhibited capacity retention of 61.9% after 100 cycles of charge-discharge tests at 100 mA/g.

Synthesis And Electrochemical Behaviors Of Li2Coxmn1-XSio4 As A Cathode Material For Lithium-Ion Batteries, Lin Wang, Dong-Ping Lv, Yong Yang

Journal of Electrochemistry

We have successfully synthesized Li₂Co_xMn_1-xSiO₄/C (x=0, 0.1, 0.3, 0.5, 1)/C composites using hydrothermal assisted sol-gel process and ball-milling method. The results of X-ray diffraction show that the solid solutions of Li₂Co_xMn_1-xSiO₄ can be achieved when x≤0.3. The initial capacities increase from 70 mAh·g^-1 of Li₂MnSiO₄/C to 105 mAh·g^-1 of Li₂Co_0.3Mn_0.7SiO₄/C. Cyclic Voltammetry (CV) curves show that the replacement of Mn with Co can reduce the electrochemical polarization, making the insertion-extraction reaction …

Synthesis Of Limnpo4/C Used As Cathode Material For Lithium Ion Batteries, Xin Yang, Xue-Wu Liu, Gui-Chang Liu, Zhi-Cong Shi, Xin Li, Guo-Hua Chen

Journal of Electrochemistry

The LiMnPO₄/C composites were prepared using a solid-state reaction with addition of the resorcinol formaldehyde resin as the carbon source. The effects of reaction temperature and time on the crystal structure, morphology and electrochemical properties of the LiMnPO₄/C composites were investigated. The results show that the best performance was achieved with the LiMnPO₄/C composites synthesized at 600 ^oC for 12 h which had the particle sizes about 100~200 nm. The initial discharge capacities were 121.6 mAh·g^-1 at 0.02C, 110 mAh·g^-1 at 0.1C and more than 60 mAh·g^-1 at 1C. An …

Runx2 Protein Expression Utilizes The Runx2 P1 Promoter To Establish Osteoprogenitor Cell Number For Normal Bone Formation, Julie C. Liu, Christopher J. Lengner, Tripti Gaur, Yang Lou, Sadiq Hussain, Marci D. Jones, Brent Borodic, Jennifer L. Colby, Heather A. Steinman, Andre J. Van Wijnen, Janet L. Stein, Stephen N. Jones, Gary S. Stein, Jane B. Lian

School of Chemical Engineering Faculty Publications

The Runt-related transcription factor, Runx2, is essential for osteogenesis and is controlled by both distal (P1) and proximal (P2) promoters. To understand Runx2 function requires determination of the spatiotemporal activity of P1 and P2 to Runx2 protein production. We generated a mouse model in which the P1-derived transcript was replaced with a lacZ reporter allele, resulting in loss of P1-derived protein while simultaneously allowing discrimination between the activities of the two promoters. Loss of P1-driven expression causes developmental defects with cleidocranial dysplasia-like syndromes that persist in the postnatal skeleton. P1 activity is robust in preosteogenic mesenchyme and at the onset …

Glucose Biosensor Using Electrospun Mn2o3-Ag Nanofibers, Shan Huang

Master's Theses

The highly porous Mn₂O₃-Ag nanofibers were fabricated by a facile two-step procedure (electrospinning and calcination) and then employed as the immobilization matrix for glucose oxidase (GOD) to construct an amperometric glucose biosensor. A notable enhancement of direct electron transfer between GOD and the electrode is observed at the Mn₂O₃-Ag-GOD modified electrode with a fast electron transfer rate constant. The biosensor also shows fast response to glucose, high sensitivity (40.60 μA×mM^-1×cm^-2), low detection limit (1.73 µM at S/N=3), low K_m,app value and excellent selectivity. These results indicate that …

Plasmonic Nanogels With Robustly Tunable Optical Properties, Tao Cong, Satvik N. Wani, Georo Zhou, Elia Baszczuk, Radhakrishna Sureshkumar

Biomedical and Chemical Engineering - All Scholarship

Low viscosity fluids with tunable optical properties can be processed to manufacture thin film and interfaces for molecular detection, light trapping in photovoltaics and reconfigurable optofluidic devices. In this work, self-assembly in wormlike micelle solutions is used to uniformly distribute various metallic nanoparticles to produce stable suspensions with localized, multiple wavelength or broad-band optical properties. Their spectral response can be robustly modified by varying the species, concentration, size and/or shape of the nanoparticles. Structure, rheology and optical properties of these plasmonic nanogels as well as their potential applications to efficient photovoltaics design are discussed.

Thermal Model For Lithium Ion Battery Pack With Mixed Parallel And Series Configuration, Meng Guo, Ralph E. White

Faculty Publications

In this work, a mathematical thermal model for lithium ion battery pack with specific configuration was developed by coupling the single particle model and energy balance equation with basic circuit constraints. The temperature variation at different parts of the battery pack was considered in charge/discharge operations, and the dependency of cell parameters on temperature were taken into account. The model was validated by comparing the simulated current, voltage, and temperature profiles with experimental data. Case studies such as battery balancing and circuit interruption were also performed and discussed.

Development Of Novel Bio/Nano Interfaces For Materials Science And Biomedical Applications, Carlee Ashley

Chemical and Biological Engineering ETDs

Virus-like particles (VLPs) of MS2 bacteriophage possess a variety of characteristics that enable their use in biomedical and materials science applications. MS2 VLPs are perfectly monodisperse and possess a highly regular periodic structure. Their protein capsids can be modified in precise locations via chemical conjugation or genetic display of peptides, and their interior volumes can be readily loaded with a variety of non-genomic materials by taking advantage of their ability to self-assemble in the presence of RNA and RNA-modified cargos. Using peptides identified by filamentous phage display, I have demonstrated the utility of MS2 VLPs as targeted nanocarriers capable of …

Roles Of Particle-Wall And Particle-Particle Interactions In Highly Confined Suspensions Of Spherical Particles Being Sheared At Low Reynolds Numbers, Ashok S. Sangani, Andreas Acrivos, Philippe Peyla

Biomedical and Chemical Engineering - All Scholarship

The roles of particle-wall and particle-particle interactions are examined for suspensions of spherical particles in a viscous fluid being confined and sheared at low Reynolds numbers by two parallel walls moving with equal but opposite velocities. Both particle-wall and particle-particle interactions are shown to decrease the rotational velocity of the spheres, so that in the limit of vanishingly small gaps between the spheres and the walls, the spheres acquire a rotational slip relative to the walls. The presence of the walls also increases the particle stresslet and, therefore, the total viscous dissipation. In the limit of vanishingly small gaps, the …

Transcriptional Analysis Of Lactobacillus Brevis To N-Butanol And Ferulic Acid Responses, James Winkler, Katy Kao

Faculty Publications

BackgroundThe presence of anti-microbial phenolic compounds, such as the model compound ferulic acid, in biomass hydrolysates pose significant challenges to the widespread use of biomass in conjunction with whole cell biocatalysis or fermentation. Currently, these inhibitory compounds must be removed through additional downstream processing or sufficiently diluted to create environments suitable for most industrially important microbial strains. Simultaneously, product toxicity must also be overcome to allow for efficient production of next generation biofuels such as n-butanol, isopropanol, and others from these low cost feedstocks.Methodology and Principal FindingsThis study explores the high ferulic acid and n-butanol tolerance in Lactobacillus brevis, a …

Electrochemical Synthesis Of Single Crystal Metal Nanowires, Nan Li

Master's Theses

Electrodeposition is an efficient and economical approach for template synthesis of one-dimensional (1D) nanostructured materials. Based on the porous membranes as templates during electrodeposition, metallic nanowires, nanorods, and nanotubes can overcome the geometrical restrictions to be inserted into the nanometric recesses with both diameter and length well controlled by tuning the size and thickness of the templates.

In this work, the morphology, growth rate and texture of copper nanowires prepared with templates were investigated by the controlled parameters in various experiments. Cu nanowire arrays with preferential orientations can be successfully synthesized into the Anodic Aluminum Oxide (AAO) templates with optimized …

Expression And Characterization Of Protein Chimera With Embedded Activated Protein C Generation, Minjeong Schneider

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

Increasing demand of medical implants has lead researchers to develop biomaterial surfaces that offer improved performance and lower thrombogenecity. There have been attempts to model biomaterial surfaces after the native endothelium as it represents an optimal non-thrombotic surface. Typically, when biomaterials are contacted with blood, they often invoke the activation of clotting cascades. Thus, to overcome surface mediated thrombotic events, proteins and molecules with anticoagulant attributes of the endothelium have been immobilized onto biomaterial surfaces. Protein C (PC) plays a main role in blood coagulation and acts as an anticoagulant when it is converted into activated protein C (APC). Activation …

Sol-Gel Derived Silver-Incorporated Titania Thin Films On Glass: Bactericidal And Photocatalytic Activity, Betul Akkopru Akgun, Anthony W. Wren, Caner Durucan, Mark R. Towler, Nathan P. Mellott

Chemical and Biochemical Engineering Faculty Research & Creative Works

Titanium dioxide (TiO₂) and silver-containing TiO₂ (Ag-TiO₂) thin films were prepared on silica pre-coated float glass substrates by a sol-gel spin coating method. The bactericidal activity of the films was determined against Staphylococcus epidermidis under natural and ultraviolet (UV) illumination by four complementary methods; (1) the disk diffusion assay, (2) UV-induced bactericidal test, (3) qualitative Ag ion release in bacteria inoculated agar media and (4) surface topographical examination by laserscan profilometry. Photocatalytic activity of the films was measured through the degradation of stearic acid under UV, solar and visible light conditions. The chemical state and …

Clinical Risk Factors For Osteoporosis In Ireland And The Uk: A Comparison Of Frax And Qfracturescores, N. M. Cummins, E. K. Poku, Mark R. Towler, O. M. O'Driscoll, S. H. Ralston

Chemical and Biochemical Engineering Faculty Research & Creative Works

Recently two algorithms have become available to estimate the 10-year probability of fracture in patients suspected to have osteoporosis on the basis of clinical risk factors: the FRAX algorithm and QFractureScores algorithm (QFracture). The aim of this study was to compare the performance of these algorithms in a study of fracture patients and controls recruited from six centers in the United Kingdom and Ireland. A total of 246 postmenopausal women aged 50-85 years who had recently suffered a low-trauma fracture were enrolled and their characteristics were compared with 338 female controls who had never suffered a fracture. Femoral bone mineral …

Effects On Hydrogen Adsorption And Activation On Platinum In A Fuel Cell Catalyst, Jack Zhang

All Dissertations

Proton exchange membrane fuel cells are a highly efficient source of power generation that is needed to sustain the energy demands of today's more environmentally conscience society. However, the presence of impurities in the hydrogen fuel stream, such as CO, H₂S, and NH₃ from the steam reforming/partial oxidation of hydrocarbons/methanol, can severely poison the Pt electrocatalyst present in the fuel cell electrode causing degradation in the fuel cell performance. To counter these poisoning effects, fuel cell manufacturers are forced to use higher Pt loadings, which dramatically increases material costs and prevents the successful commercialization of the technology. …

Oxygenate Synthesis During Co Hydrogenation On Cocuzno- Based Catalysts, Yu-Tung Tsai

All Dissertations

The research of catalytic synthesis of methanol and other higher alcohols from CO hydrogenation has received great attention since 1980s. The focus of this research is to establish a better fundamental insight into heterogeneous metal catalysts for oxygenate (especially alcohol) synthesis by CO hydrogenation.
Co-based catalysts have been reported widely as the high-performance Fischer-Tropsch Synthesis (FTS) catalysts. The solid base, hydrotalcite (HT), using as a support for Co catalysts resulted in higher activity for CO hydrogenation comparing to other supports (pre-calcined hydrotalcite, MgO and Al₂O₃). The activities of Co/HT reduced at different reduction temperatures (300-600oC) were …

Traffic Safety: Modeling, Analysis And Visualization, Puneet Lakhanpal

UNLV Theses, Dissertations, Professional Papers, and Capstones

Traffic Safety has always been one of the major issues of concern in United States. Every year, stringent efforts are made by the national agencies and safety offices to uplift the traffic safety standards and build systems which can guide them in policy making, reducing crashes and routing the financial resources in an optimal direction. This thesis studies the traffic safety from three different angles: modeling, analysis and visualization. In the beginning, these three components are explored in the domain of Injury Severity. Later on, the focus is shifted towards the Traffic Safety related to Safety Belts. Factors and models …

Controlled Release Of 6-Aminonicotinamide From Aligned, Electrospun Fibers Alters Astrocyte Metabolism And Dorsal Root Ganglia Neurite Outgrowth, Nicholas J. Schaub, Ryan J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Following central nervous system (CNS) injury, activated astrocytes form a glial scar that inhibits the migration of axons ultimately leading to regeneration failure. Biomaterials developed for CNS repair can provide local delivery of therapeutics and/or guidance mechanisms to encourage cell migration into damaged regions of the brain or spinal cord. Electro spun fibers are a promising type of biomaterial for CNS injury since these fibers can direct cellular and axonal migration while slowly delivering therapy to the injury site. In this study, it was hypothesized that inclusion of an anti-metabolite, 6-aminonicotinamide (6AN), within poly-l-lactic acid electro spun fibers could attenuate …

Simulation Of Dna Extension In Nanochannels, Yanwei Wang, Douglas R. Tree, Kevin D. Dorfman

Faculty Publications

We have used a realistic model for double-stranded DNA and Monte Carlo simulations to compute the extension (mean span) of a DNA molecule confined in a nanochannel over the full range of confinement in a high ionic strength buffer. The simulation data for square nanochannels resolve the apparent contradiction between prior simulation studies and the predictions from Flory theory, demonstrating the existence of two transition regimes between weak confinement (the de Gennes regime) and strong confinement (the Odijk regime). The simulation data for rectangular nanochannels support the use of the geometric mean for mapping data obtained in rectangular channels onto …

Enhanced Degradation Of Fats, Oils And Greases In Domestic Wastewater Sewer Networks And Grease Interception Systems Using Peat Humic Substances, Matthew Hunnemeder

Theses and Dissertations

The efficacy of peat humic substances in enhancing the degradation of fats, oils and greases (FOG) was investigated under controlled laboratory conditions using bench scale well-mixed bioreactors. An experimental design was used to evaluate the effects of temperature and peat humic substance (PHS) concentration on FOG degradation in domestic wastewater for a temperature range from 10 deg.C to 30 deg.C and a PHS concentration range from 0 to 20 ppm(v). Factors and interactions significantly affecting the rate of FOG degradation were identified, and models to predict FOG degradation rates as a function of PHS concentration and temperature were developed. The …

Desorption Kinetics Of An Alternative Monoethanolamine Based Co2 Capture Process, Morris D. Argyle, Zhuoyan Sun, Maohong Fan

Faculty Publications

Supported monoethanolamine (MEA) sorbents are promising materials for CO2 separation due to their low energy demands. Like any other CO2 separation technologies, CO2 desorption from supported MEA sorbents is the most energy-expensive step in the overall CO2 separation process. The presence of water during CO2 desorption process leads to a significant increase in energy consumption. Therefore, CO2 desorption in the absence of water is an important method to reduce energy consumption of CO2 separation using supported MEA, which is determined by several major factors, including desorption kinetics. However, study on CO2 desorption kinetics of supported MEA is lacking. This research …

Eddy Impaction As An Ash Deposition Mechanism: A Theoretical And Experimental Investigation, Minmin Li

Theses and Dissertations

The eddy impaction ash deposition model derived and validated in this document predicts eddy impaction rates as a function of turbulence intensity, boundary layer thickness, and gas velocity. The experimental apparatus introduces small particles (200 nm, 25 µm, and 500 µm diameter) into a gas stream flowing through a horizontal pipe (Re 2,300-8,000). The particles deposit on the pipe wall and the total mass of impacted particles provides a measure of collection efficiency. Experimental results indicate deposition velocity increases with Reynolds number, consistent with eddy impaction theory and based on increased turbulent energy. Eddy impaction also increases with particle size …

Prediction Of Fluid Dielectric Constants, Jiangping Liu

Theses and Dissertations

The dielectric constant or relative static permittivity of a material represents the capacitance of the material relative to a vacuum and is important in many industrial applications. Nevertheless, accurate experimental values are often unavailable and current prediction methods lack accuracy and are often unreliable. A new QSPR (quantitative structure-property relation) correlation of dielectric constant for pure organic chemicals is developed and tested. The average absolute percent error is expected to be less than 3% when applied to hydrocarbons and non-polar compounds and less than 18% when applied to polar compounds with dielectric constant values ranging from 1.0 to 50.0. A …

Thermoelectric Power Factor Of In2O3:Pd Nanocomposite Films., Otto J. Gregory, Matin Amani, Gustave C. Fralick

Chemical, Biomolecular, and Materials Engineering Faculty Publications

A nanocomposite exhibiting large thermoelectric powers and capable of operating at temperatures as high as 1100 °C in air was fabricated by embedding palladium nanoparticles into an indium oxide matrix via co-sputtering from metal and ceramic targets. Combinatorial chemistry techniques were used to systematically investigate the effect of palladium content in these nanocomposite films on thermoelectric response. Based on these rapid screening experiments, the thermoelectric properties of the most promising nanocomposites were evaluated as a function of post-deposition heat treatment at high temperatures. An n-type nanocomposite film was developed exhibiting a power factor of 4.5 x 10^-4 W/m·K^{2 …}

Selective Epitaxial Growth Techniques To Integrate High-Quality Germanium On Silicon, Darin Leonhardt

Chemical and Biological Engineering ETDs

High-quality Ge-on-Si heterostructures have been actively pursued for many advanced applications, including near-infrared photodetectors, high-mobility field effect transistors, and virtual substrates for integrating III-V multijunction solar cells. However, growing epitaxial Ge on Si poses many engineering challenges, ranging from lattice mismatch, to thermal expansion coefficient mismatch, to non-planar morphological evolution. The lattice mismatch between Ge and Si often leads to a high density of threading dislocations. These dislocations, if not reduced, propagate through the subsequently grown GaAs layer, deteriorating its quality. To overcome these engineering challenges, we have developed three different approaches based on molecular beam epitaxy to significantly reduce, …

Integration Of Composite Nanomaterials Into Anode And Cathode Designs, Claudia Wuillma Narváez Villarrubia

Chemical and Biological Engineering ETDs

This research introduces the use of bucky' papers based on SWNTs as anode electrode materials for the oxidation of NADH and L-Malate oxidation by poly(methylengreen) and malate dehydrogenase respectively. SWNTs were used to create an electrode design consisting of high surface area-hierarchically ordered carbon nanomaterials with controlled surface chemistry. Additionally, this research introduces new cathodes designs based on buckeye and toray papers for air-breathing and liquid electrolyte modes. Buckeye and 0.11mm-thick toray papers are used to design the air-breathing cathode by immobilization of Laccase using a non-covalent linking agent. The liquid electrolyte cathode, designed to be applied in implantable devices, …

Assessment Of The Biocompatibility, Stability, And Suitability Of Novel Thermoresponsive Films For The Rapid Generation Of Cellular Constructs, Jamie Reed

Chemical and Biological Engineering ETDs

Stimuli responsive polymers (SRP) are of great interest in the bioengineering community due to their use in applications such as drug delivery and tissue engineering. One example of an SRP is poly(N-isopropyl acrylamide) or pNIPAM. This SRP has the capability of changing its conformation with a slight temperature change: adherent mammalian cells spontaneously release as a confluent cell sheet, which can be harvested for cell sheet engineering purposes. Since its initial use in 1968, many researchers have used pNIPAM to obtain a cell sheet composed of their cell type of interest. The differing protocols used for these diverse cell types, …