Chemical Engineering Commons^™

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, …

The Occurrence Of False Positive Tests For Gunshot Residue Based On Simulations Of The Suspect's Occupation, Christopher R. Dockery, Matthew B. Rosenberg, Kimberly Kammerdiener, Lauren E. Mcadams

Faculty Articles

Samples collected from high-risk occupations, or simulations thereof, are analyzed for elemental composition using laser-induced breakdown spectroscopy (LlBS) to determine the occurrence of false positive gunshot residue results generated in the work environment. Previous work involving the study of lifetime of detectable amounts of gunshot residue on the hands of a suspect shooter found that gunshot residue exists up to 5.27 days after a firearm discharge. However, certain environmental and/or occupational false positive tests for gunshot residue could result when sampling non-shooters. Samples collected from occupations or simulations thereof include welding, pyrotechnics, key cutting, mechanics, and paper products all of …

Detection Of Specific Biological Antigens Using Ac Electrochemical Impedance Spectroscopy, Darrel Angelo Mazzari

Dissertations (1934 -)

When certain antigens are present in our environment, a rapid, on-site, accurate, selective, and repeatable detection method can be invaluable in preventing illness or saving lives. Rapid detection of these antigens is important to avert spreading infections.

Currently, capturing a sample and sending it to a laboratory can take weeks to get results, which can be much too long. Conventional sensing methodologies include various electrical measurements as capacitive, potentiometric, piezoelectric, surface plasmon resonance (SPR), and quartz crystal microbalance (QCM). Of particular power and interest is Alternating Current (AC) Electrochemical Impedance Spectroscopy (EIS) which provides for the characterization of the electrical …

Synthesis And Characterization Of Tethered Poly(N-Isopropylacrylamide) For Quantitative Cell Adhesion Studies, Phanindhar J. Shivapooja

Chemical and Biological Engineering ETDs

Environmentally responsive (or smart') polymers represent a new approach for controlling biofouling release. Poly(N-isopropylacrylamide) (PNIPAAm) is a thermo responsive polymer that can potentially be used to control biofouling, as it exhibits a change in its relative hydrophobicity above and below its lower critical solution temperature (LCST ~ 32\uf0b0C). This thesis reports on grafted PNIPAAm brushes, synthesized using a relatively simple and rapid method which allows atom transfer radical polymerization (ATRP) in presence of air. In this study the structure, purity and thermally responsive behavior of grafted brushes have been characterized using X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy, Fourier …

Ionic Self-Assembly Of Porphyrin Micro-Nano Structures For Solar Hydrogen Evolution, Yongming Tian

Chemical and Biological Engineering ETDs

This research project develops self-assembled porphyrin micro-nano structures and their metal nanocomposites for efficient solar H2 evolution. The project is composed of three inter-related tasks. The first task is to develop the synthetic methods for preparing the binary porphyrin micro-nano structures by ionic self-assembly under various aqueous solution conditions. Although the porphyrin molecules have been widely studied in artificial photosynthesis, the porphyrin monomers absorb light in a limited range of the solar spectrum and are unstable in solution. In using ionic selfassembly of two oppositely charged porphyrin molecules, we successfully synthesized the more robust micro/nano clover-like structures to replace the …

Effect Of Freshman Chemistry On Student Performance In Sophomore Engineering Courses, Michael A. Collura, Shannon Ciston, Nancy Ortins Savage

Chemistry and Chemical Engineering Faculty Publications

The role of first year chemistry courses in engineering programs varies somewhat across programs and disciplines. Clearly most engineering majors will encounter chemistry topics of a general nature in some of their upper-level course work. The purpose of requiring chemistry in the first year, however, goes well beyond learning chemical concepts. As a quantitative science, chemistry requires the use of math, principally algebra, on a regular basis in solving various problems. Students should gain an appreciation of the importance of units in solving problems should come to understand the difference between implicit and explicit properties and should develop other quantitative …

An Argument For The Importance Of Material Property Characterization Of Hydrogels, J. M. Zuidema, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrogels are being fabricated for use in many tissue engineering applications. In order to advance the field, material properties must be characterized to determine the most desirable attributes. The data presented shows the importance of both surface charge and mechanical properties on dorsal root ganglia neurite extension. © 2011 IEEE.

Aluminium-Free Glass Polyalkenoate Spinal Cements, A. W. Wren, N. M. Cummins, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Addition of Yitanium increased the Wt & St and the sf strength of these cements compared to the control (BT 101). © 2011 IEEE.

Fabrication And Characterization Of A Hydrogel Containing Electrospun Fibers, C. J. Rivet, R. J. Gilbert

Chemical and Biochemical Engineering Faculty Research & Creative Works

Electro spun an fibers hydrogels are two focal points of research within the biomaterial's community. The electrospinning process allows for fabrication of nanoscale, aligned topography and has been shown to direct cellular migration and outgrowth. Hydrogels exhibit benefits over traditional, rigid scaffolds in that they are injectable and can be tailored to mimic the mechanical properties of the surrounding tissue. Although both electro spun fibers and hydrogels display favorable characteristics for biomedical applications in vitro, there in vivo benefits are limited due to inherent deficiencies Therefore, to advance the field of biomaterials research, a composite material containing electro spun fibers …