Engineering Commons^™

Continuous Monitoring Of Bioactive Glass Conversion Using Optical Biosensors, Prajakta Bhagwat

Masters Theses

"The engineered regeneration of bone is a significant challenge being undertaken to treat conditions such as traumatic casualties, bone cancer, osteoporosis, etc. Advances in hard tissue regrowth may potentially lead to significantly improved lives for millions of people. Bioactive glasses as potential materials in the fabrication of scaffolds for hard tissue regeneration have been studied recently. Bone regrowth requires maintenance of optimal levels of oxygen, glucose, phosphate, calcium, and pH. Current work at Missouri S & T's Center for Bone and Tissue Repair and Restoration focuses on developing optical biosensors to monitor: conversion of bioactive glass to hydroxyapatite, ease of …

Mesh Optimization Of Finite Element Models Of Wellbore Stress Analysis, Ming-Yen Lee

Masters Theses

"Numerical modeling methods such as the widely used finite element method provide an excellent opportunity to analyze the wellbore state of stress for a variety of applications such as wellbore integrity, wellbore design or hydraulic fracturing. However, numerical modeling methods introduce errors by nature and may not precisely match the analytical solution if the meshing of the numerical model is not carefully taken care of. This study presents a parametric study of the meshing parameters mesh density, element type, and model size for 2-dimensional and 3-dimensional vertical wellbore models under three different types of boundary conditions, and a guideline for …

Thermomechanics Of Curves In Space, Pavan Krishna Kanchi

Masters Theses

"Several biological molecules are known to form helices and coiled structures, such as DNA, collagen, bacterial flagella, and proteins. The backbones of such molecules may be modeled as a curve in three dimensions. A variational problem for the functional of the total free energy required to perturb moving curves in space is considered. The total energy of a curve in three dimensions is minimized y with a general intensive energy, which is a function of position, and the invariants, curvature and torsion. Three types of moduli are identified: stretching, bending and torsional moduli. As a result, three independent force balances …

The Feasibility Of Using Bifidobacteria Bifidum (Atcc 700541) For The Production Of Prebiotic Oligosaccharides, Candice Marie Luehrs

Masters Theses

"Galactooligosaccharides (GOS) are prebiotics that are being used to influence intestinal microbiota towards health promoting, beneficial bacteria like bifidobacteria. Natural sources of GOS are not found in suitable levels to achieve the desired health effects so economically viable commercial production methods are important. Enzymatic conversion of lactose to GOS through transgalactosylation is a preferred method since the starting material is inexpensive and readily available. Enzymes used in batch production are purified from fungal or bacterial sources or remain in whole cells cultured for GOS production. Purified or unbound enzymes are single use whereas enzymes retained within whole cells can potentially …

Fourier Transform Emission Spectroscopy Of Yh And Yd: Observation Of New A¹Δ And B¹Π Electronic States, R. S. Ram, G. Li, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The emission spectra of YH and YD molecules have been investigated in the 3600–12 000 cm⁻¹ region using a Fourier transform spectrometer. Molecules were formed in an yttrium hollow cathode lamp operated with a continuous flow of a mixture of Ne and Ar gases, and YH and YD were observed together in the same spectra. A group of bands observed near 1 μm have been identified as 0-0 and 1-1 bands of the A¹Δ-X¹Σ⁺ and B¹Π-X¹Σ⁺ transitions of YH and the 0-0 bands of the same two transitions …

Understanding And Improving Lithium Ion Batteries Through Mathematical Modeling And Experiments, Rutooj D. Deshpande

Theses and Dissertations--Chemical and Materials Engineering

There is an intense, worldwide effort to develop durable lithium ion batteries with high energy and power densities for a wide range of applications, including electric and hybrid electric vehicles. For improvement of battery technology understanding the capacity fading mechanism in batteries is of utmost importance. Novel electrode material and improved electrode designs are needed for high energy- high power batteries with less capacity fading. Furthermore, for applications such as automotive applications, precise cycle-life prediction of batteries is necessary.

One of the critical challenges in advancing lithium ion battery technologies is fracture and decrepitation of the electrodes as a result …

Mathematical Modeling Of Clostridium Thermocellum’S Metabolic Responses To Environmental Perturbation, Bless Adotey

Theses and Dissertations--Biosystems and Agricultural Engineering

Clostridium thermocellum is a thermophilic anaerobe that is capable of producing ethanol directly from lignocellulosic compounds, however this organism suffers from low ethanol tolerance and low ethanol yields. In vivo mathematical modeling studies based on steady state traditional metabolic flux analysis, metabolic control analysis, transient and steady states’ flux spectrum analysis (FSA) were conducted on C. thermocellum’s central metabolism. The models were developed in Matrix Laboratory software ( MATLAB^® (The Language of Technical Computing), R2008b, Version 7.7.0.471)) based on known stoichiometry from C. thermocellum pathway and known physical constraints. Growth on cellobiose from Metabolic flux analysis (MFA) and Metabolic …

Simulation Of Cell Seeding And Retention In A Disordered Polymeric Scaffold, Tejaswini Narayana

LSU Master's Theses

Historically, bone repair has been performed using materials like metals, ceramics, cements and bioactive glass. The major problem with all these materials is that they do not perform the necessary non-structural functions of bone. Engineered tissue, created by growing bone cells on porous biodegradable material (scaffold), will address this issue with current bone repair techniques. Improving engineered tissue treatments requires a thorough understanding of factors affecting cell seeding and proliferation inside a disordered porous material which is not feasible using current experimental techniques. A model for particle transport in a disordered porous material that can predict the particle deposition pattern …

New Media Icc Profiles Construction And Concerns, Reem El Asaleh

Dissertations

With the advent of the modern digital technology, users can now capture an image and reproduce it between different media, such as display it on LCD monitor or tablet computer, print it on desktop printer or send it to a printing press. The challenge has been then to maintain the accuracy of image colors during this reproduction, which has led to the development of Color Management Systems. Using these systems, the color reproduction across-media will be accomplished using device ICC profiles that describe each device’s color characterization data in a standardized format based on International Color Consortium (ICC) specifications.

ICC …

Boron And Rare Earth Oxide Composite Nanoparticles For Enhancement Of Combustion, Jacob Hanberry

LSU Master's Theses

Metallic fuels are of interest as additives in bio-fuel combustion because of their high heating values, and this thesis deals with the experimental investigation of boron nanoparticles and their effect on ethanol combustion. Two grades of boron nanoparticles were commercially purchased and modified to obtain different physical characteristics, by ball milling and sintering. Also, a mixture of rare-earth oxide (CeO2, La2O3, and Gd2O3) nanoparticles was synthesized and added to the boron nanoparticles in varying amounts to form composite mixtures. The effects of rare-earth oxides on boron combustion were investigated using these composites. Particle characterizations were carried out by X-ray diffraction, …

The Stereospecific Hydrogenation And Dehydrogenation Of Rosin And Fatty Acids, Edward O'Brien

LSU Master's Theses

Tall oil is a byproduct of the standard wood pulping process in the paper industry. It is primarily made up of C:18 fatty acids, rosin acids and a minor fraction of neutrals. Normally, tall oil is further distilled into fractions and then hydrogenated or dehydrogenated into different products. In this project, three heterogeneous catalytic methods of producing byproducts of various distilled tall oil fractions were examined at lower temperatures and pressures than the industry norm in an attempt to develop cheaper production processes. Reactions were conducted in stirred batch reactors of different sizes and product compositions were analyzed primarily by …

Photoelectrochemical Etching Of Isolated, High Aspect Ratio Micorstructures In N-Type Silicon (100), Purnima Narayanan

LSU Master's Theses

Three-dimensional integration techniques have become increasingly popular to meet the ever rising demand of high capacity and reduced package size in microelectronics devices. Through Silicon Vias (TSVs) offer an efficient method to achieve 3D packaging with shorter interconnection length and higher interconnect density relative to conventional wire bonding. Wet electrochemical etching is a simple technique which may be used to create deep structures in silicon and is relatively low cost compared with Reactive Ion Etching or Laser drilling. Historically, a primary challenge is passivating TSV (macropore, microstructure) sidewalls against etching at sidewall thickness greater than twice the depletion region width. …

Electrochemical Reduction Of Co2 To Methanol, Minh Tuyen Hoang Le

LSU Master's Theses

An efficient method to convert CO2 to fuels using renewable energy could displace crude oil without increasing CO2 emission and provide high-density energy storage reservoirs similar to liquid fuels or batteries. Although photoelectrochemical conversion of CO2 is possible, solar-to-fuel efficiencies are lower than the combination of conventional photovoltaics (up to 40% efficiency) and electrochemical cells (up to 80% Faradaic efficiency). In the electrochemical case, electrical energy from renewable sources may be converted to hydrocarbons or alcohols using electrocatalysts. The direct reduction of CO2 to CH3OH is known to occur at several types of electrocatalysts including oxidized Cu electrodes. In this …

Modeling Effects Of Coupled Convection And Co2 Injection In Stimulating Geopressured Geothermal Reservoirs, Tatyana Plaksina

LSU Master's Theses

Geopressured geothermal brines are a vast geothermal resource in the US Gulf of Mexico region. In particular, geopressured sandstones near salt domes are potential sources of geothermal energy because salt diapirs with high thermal conductivities may pierce younger, cooler strata. These characteristics enhance transfer heat from older, hotter strata at the base of the diapir into shallower strata. Moreover, widespread geopressure in the Gulf region tends to preserve permeability, enhancing productivity. As an example, the Camerina A sand of South Louisiana was chosen as a geomodel for a numerical simulation study of effects of CO2 injection and coupled convection as …

Stochastic Modelling Of Eukaryotic Cell Cycle, Murali Krushna Koneru

LSU Master's Theses

Stochastic models are developed to capture the inherent stochasticity of the biochemical networks associated to many biological processes. The objective of the present thesis is to present a detailed picture of stochastic approach for the mathematical modeling of eukaryotic cell cycle, to demonstrate an important application of such model in chemotherapy and to present a methodology for selecting the model parameters. The stochastic cell cycle model, developed using stochastic chemical kinetics approach, leads to the formation of an infinite dimensional differential equation in probabilities of system being in a specific state. Using Monte Carlo simulations of this model, dynamics of …

Molecular Dynamics Of Ionic Liquids In Nanoporous Electrodes, Nav Nidhi Rajput

LSU Master's Theses

Molecular dynamics simulations were performed to investigate the structural and dynamical properties of ionic liquid (IL) [EMIM+][TFMSI-] confined inside slit-like graphite pores. ILs are salts composed of an organic cation and an organic or inorganic anion with melting point below 100ºC. Their unique properties such as great thermal and chemical stability have gained them immense attention in recent years. The main goal of this research is to understand how molecular level properties of ILs are affected by the properties of the nanoporous materials. The results obtained in this work indicate that pore size has a profound effect on structural and …

Evaluation Of Simultaneous Water And Gas Injection Using Co2, Shrinidhi Shetty

LSU Master's Theses

Miscible CO2 injection is the second largest contributor to global enhanced oil recovery, as it has successfully undergone extensive laboratory tests and field applications for recovering residual oil left behind after waterflooding. Prolific incremental recoveries have been obtained for some fields. Although miscible CO2 injections generally have excellent microscopic displacement efficiency they often result in poor sweep efficiency. In order to address sweep problems and maximize recoveries, other schemes of gas injection have been developed. Two such processes are water-alternating-gas (WAG) and simultaneous water-and-gas (SWAG) injection. WAG and SWAG have been successfully used to minimize poor sweep. Improved gas utilization …

Pore-Scale Lattice Boltzmann Simulations Of Inertial Flows In Realistic Porous Media: A First Principle Analysis Of The Forchheimer Relationship, Chukwudi Paul Chukwudozie

LSU Master's Theses

With recent advances in the capabilities of high performance computing (HPC) platforms and the relatively simple representation of complex geometries of porous media, lattice Boltzmann method (LBM) has gained popularity as a means of solving fluid flow and transport problems. In this work, LBM was used to obtain flow parameters of porous media, study the behavior of these parameters at varying flow conditions and quantify the effect of roughness on the parameters by relating the volume averaged flow simulation results to Darcy and Forchheimer equations respectively. To validate the method, flow was simulated on regular and random sphere arrays in …

Electrochemical Etching Of Isolated Structures In P-Type Silicon, Joel Nino Bugayong

LSU Master's Theses

The role of the space charge region (SCR) was demonstrated in isolated structures for the first time. Electrochemical etching was conducted in differently pitched structures in p-type silicon. A design of experiment was also performed to evaluate the effect of electrolyte and applied potential. Finally chemical etching was demonstrated as a possible post-etch clean to porous structures. The results showed that the morphology of etched structures in pre-patterned silicon is strongly influenced by the SCR even in isolated structures. Using lightly-doped p-type Si (1,000-10,000 Ω-cm), deep macropores were obtained in wide-pitched patterns. However, the diameter of the pores grew larger …

Analytical Design Method For Cold Production Of Heavy Oil With Bottom Water Using Bilateral Sink Wells, Wenting Qin

LSU Doctoral Dissertations

Few heavy oil reservoirs with strong bottom water drives have been developed successfully because of severe water coning. Water coning tends to cause low ultimate recovery, low well productivity, and high water production. Although thermal and gravity-assisted methods might improve recovery in oil reservoirs, such methods are widely perceived as either economically unfavorable or technologically infeasible. This study proposes a new, cold production technique, called Bilateral Water Sink (BWS), to meet those challenges. The BWS method suppresses water cresting by producing oil and water simultaneously from separate, horizontal wells completed in the oil and water zones; the oil and water …

Silicon Nanowire Anode For Lithium-Ion Batteries: Fabrication, Characterization And Solid Electrolyte Interphase, Wanli Xu

LSU Doctoral Dissertations

Depletion of fossil fuels and concerns over CO2 emission have driven the development of electric vehicles (EVs) with high-energy efficiencies and low emissions. Lithium-ion rechargeable batteries, compared to lead acid, nickel cadmium, nickel metal hydroxide, and other popular rechargeable batteries, are considered as the most promising candidates for EVs for their high operating voltage and high energy density. Silicon nanowires are considered as lithium-ion battery anodes for their ultra high capacity at 4200 mAh·g-1 (10× higher than conventional graphite anode), as well as stress accommodation for reversible lithiation and delithiation. Silicon nanowires were fabricated via metal assisted electroless etching, and …

Photochemical Reaction Products Of Polycyclic Aromatic Hydrocarbons Adsorbed At An Air-Water Interface, Franz Stefan Ehrenhauser

LSU Doctoral Dissertations

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous pollutants resulting from incomplete combustion and hence normally unavoidable. The kinetic aspects of the environmental degradation process have received considerable attention; however, not much is known about the degradation products themselves. Aqueous solutions of naphthalene, acenaphthene, 9H-fluorene, phenanthrene and pyrene were subjected to UVB light in a bulk-phase and a thin-film reactor to assess the identity of the formed photodegradation products. To aide in the challenging analysis of these mixtures, a novel analytical technique based on high performance liquid chromatography (HPLC) coupled to UV diode-array detection and dopant-assisted atmospheric pressure photoionization mass …

Supercritical Pyrolysis Of Toluene, Khue Dang Nguyen

LSU Master's Theses

The development of future high-speed aircrafts will required the jet fuel to act as the primary engine coolant to absorb excess heat produced by the engine components. To aid in removing the excess heat and reducing the aircraft’s weight, future jet fuels used for high-speed aircrafts will act as both coolant and fuel; however, by exposing the fuels to temperatures and pressures above their critical point, they undergo pyrolysis to form larger and/or more abundant polycyclic aromatic hydrocarbons (PAH) and eventually carbonaceous solid deposits in the pre-combustion environment. The formation of solid deposits in the pre-combustion environment results in clogging …

Developing A Tool To Characterize The Ultradian Rhythm In Diploid Saccharomyces Cervisiae Using The Reporter Gene Green Fluorescent Protein, Imran Chiragh

LSU Master's Theses

Biological rhythms control many temporal behaviors of organism, such as the sleep cycle, hearts rhythms, seasonal animal migrations etc. Understanding these rhythms would provide insight into the temporal process of living organisms. Saccharomyces cerevisiae, a budding yeast, is an ideal model organism to study biological rhythms in eukaryotic cells because of its sequenced genome and discerned processes. By characterizing the biological rhythm in budding yeast, insight can be gained into more complex organisms. Previous studies have exhibited oscillatory behavior of oxygen consumption and determined that deletion of the GTS1 gene dissipates this rhythm. However, to further understand the specific behavior …

Numerical Studies Of Flow In Porous Media Using An Unstructured Approach, Nathan Matthew Lane

LSU Doctoral Dissertations

Flow and transport in porous media is relevant to many areas of engineering and science including groundwater hydrology and the recovery of oil and gas. Porous materials are characterized by the unique shape and connectivity of the internal void structures which give rise to a large range in macroscopic transport properties. Historically an inability to accurately describe the internal pore-structure has prevented detailed study of the role of pore structure on transport. In recent decades however, the combination of high resolution imaging technologies with computational modeling has seen the development of fundamental pore-scale techniques for studying flow in porous media. …

Simulation Study Of Sweep Improvement In Heavy Oil Co2 Floods, Venu Gopal Rao Nagineni

LSU Master's Theses

Enhanced oil recovery by CO2 injection is a common application used for light oil reservoirs since CO2 is relatively easily miscible with light oils. CO2 flooding in heavy oil reservoirs is often uneconomic due to unfavorable mobility ratios. Reservoir heterogeneity further complicates the process as CO2 channels through high permeability layers leading to premature breakthrough. However, this can be controlled by choosing a suitable modification to the CO2 injection process enabling better sweep efficiencies, and making the process economic. The current work focuses on two such methods; water-alternating-gas injection (WAG) and profile modification by blocking gas flow in the high …

Catalytic Process For The Conversion Of Synthesis Gas To Ethanol For Use As An Alternative Fuel, Nitin Kumar

LSU Doctoral Dissertations

Higher alcohols are increasing as a proportion of the transportation fuel market, and can be used as neat fuels, or as blends with conventional fuels. For a number of reasons, these C2+-alcohols will be of interest in the foreseeable future. Large-scale production of higher alcohols will likely be carried out via syngas, which can be produced from a number of feedstocks, including coal, natural gas and biomass. Rhodium-based catalysts have been found to be the most active/selective for higher alcohols. However, the literature shows that the yields of C2+-alcohols that can be achieved with current catalysts, even the most active/selective, …

Surface Functionalization Of Crystalline Silicon Substrates, Sri Sai Vegunta

LSU Doctoral Dissertations

In this work, various chemical and electrochemical methods were demonstrated to attach application-specific organic monolayers to crystalline silicon substrates. In one study, alkyl monolayers were anodically electrografted or thermally grafted onto planar (100) silicon substrates using Grignard precursors. The results show electrografted methyl monolayers provide a stable Si-C termination, resisting oxidation on (100) surfaces for approximately 55 days in air. The alkyl termination could provide a potential alternative to defective native oxides and kinetically unstable hydride surfaces. A mechanism involving two electron transfers per grafting event was established for both the thermal and electrochemical routes. In another study, unsaturated organic …

Characterization Of Foam Flow In Pipes Using Two Flow Regime Concept, Rahul Narayanrao Gajbhiye

LSU Doctoral Dissertations

The objective of this study is to investigate the characteristics of foam flow behavior in pipes in a wide range of experimental conditions, including two pipe materials (stainless steel and nylon pipes with about 0.36 - 0.38 inch in inner diameter and 12 ft in length), three surfactant formulations (Cedepal FA-406, Stepanform-1050, and Aquet-944), and three surfactant concentrations (0.1, 0.5, and 5 wt%). The concept of “two foam-flow regimes”, consisting of high-quality regime and low-quality regime, is at the heart of interpreting the experimental data. The experimental results in horizontal pipes showed the presence of two distinct high-quality and low-quality …

Dry Reforming Of Methane On Rhodium And Nickel Substituted Pyrochlore Catalysts, Sarthak Gaur

LSU Master's Theses

Dry reforming of methane (DRM) has been widely investigated, with most studies showing rapid deactivation due to carbon deposition. This suggests a need to develop catalysts that limit carbon formation while avoiding structural changes at the elevated temperatures typical of this reaction. Here, we report CO2 reforming of methane on four pyrochlore catalysts. First, Rh was partially substituted for Zr in lanthanum zirconate (La2Zr2O7) to give La2Zr2-xRhxO7.5 (LRZ, x=0.112, 2 wt% Rh) pyrochlore. A second pyrochlore catalyst was synthesized in which Ca was further substituted into the La-site to give La1.95Ca0.05Zr2-xRhxO7 (LCRZ, x=0.055, 1 wt% Rh). A third catalyst was …