Engineering Commons^™

Pichia Pastoris Fermentation With Mixed-Feeds Of Glycerol And Methanol: Growth Kinetics And Production Improvement, Wenhui Zhang, Karen J. Hywood Potter, Bradley A. Plantz, Vicki L. Schlegel, Leonard A. Smith, Michael M. Meagher

Papers in Biochemical Engineering

Fed-batch fermentation of a methanol utilization plus (Mut+) Pichia pastoris strain typically has a growth phase followed by a production phase (induction phase). In the growth phase glycerol is usually used as carbon for cell growth while in the production phase methanol serves as both inducer and carbon source for recombinant protein expression. Some researchers employed a mixed glycerol-methanol feeding strategy during the induction phase to improve production, but growth kinetics on glycerol and methanol and the interaction between them were not reported. The objective of this paper is to optimize the mixed feeding strategy based on growth kinetic studies …

Mass Transfer Coefficients For Laminar Longitudinal Flow In Hollow-Fibre Contactors, Ashok S. Sangani, Sangkyun Koo

Biomedical and Chemical Engineering - All Scholarship

We consider the problem of predicting the rate of mass transfer to a fluid flowing parallel to the axes of randomly placed aligned tubes, a model of hollow-fibre contactors. The analysis is carried out for the limiting cases of short contactors, for which the concentration boundary layers remain thin compared with the radius of the tubes, and for the fully developed case corresponding to very long tubes. Numerical simulations for random arrays are carried out for N randomly placed tubes within a unit cell of a periodic array. It is shown that the mass transfer coefficient for the fully developed …

Experimental Energy Performance Of Open Cooling Towers Used Under Low And Variable Approach Conditions For Indirect Evaporative Cooling Of Buildings, Ben Costelloe, Donal Finn

Articles

The success of chilled ceilings and displacement ventilation systems as a means of sensible cooling in buildings has prompted a review of evaporative cooling technology as an effective means of generating the required cooling water. When such cooling water is generated at low approach conditions (2–5 K), at the higher temperatures required in these systems (14–18°C), very high levels of availability result. In many north western European locations the levels of availability are such that the prospect of supplanting rather than simply supplementing the refrigeration system, for sensible cooling purposes, arises. The viability of the technique, however, largely depends on …

Using Psychotherapy Techniques To Reveal Misconceptions And Improve Learning, Paul Michael Santi, Michele M. Santi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

When students are aware that they do not understand a concept, the main impediment to developing an understanding is their willingness to ask questions of the instructor or of fellow students. When students think that they understand a concept, but really have some significant misconception lodged in their mental picture of the concept, they may not supplant this misconception for years, if ever. Both situations can be corrected if the students identify the need to ask questions, are brave enough to do so in the traditional academic settings, and if the answers adequately address the actual misunderstanding (which may be …

Silica Coating Of Gold Nanoparticles, Milind Laxman Surve

Masters Theses

“Gold colloids have been homogenously coated with silica using silane coupling agents as a primer to make the gold surface vitreophilic. After adding active silica, the particles are transferred in ethanol for uniform silica coating by using the Stober method. Gold nanoparticles used for this study ranged from 5 nm up to 40 nm with mixed results. Silica condensation can be controlled to produce different silica thicknesses on gold. The main problem while coating smaller particles (5 nm and 10 nm) was the final coagulation or necking of silica after coating the gold surface. The possible causes for this effect …

Sequence Dependent Mobility Of Short Oligonucleotides In Free-Solution Electrophoresis, James D. Sterling, Eve F. Fabrizio, Ali Nadim

Business and Information Technology Faculty Research & Creative Works

No abstract provided.

Scale-Up Of The Fermentation And Purification Of The Recombinant Heavy Chain Fragment C Of Botulinum Neurotoxin Serotype F, Expressed In Pichia Pastoris, Scott K. Johnson, Wenhui Zhang, Leonard A. Smith, Karen J. Hywood-Potter, S. Todd Swanson, Vicki L. Schlegel, Michael M. Meagher

Michael Meagher Publications

A recombinant heavy chain fragment C of botulinum neurotoxin serotype F (BoNTF(Hc)) has been expressed in Pichia pastoris for use as an antigen in a proposed human vaccine. P. pastoris cells were grown using glycerol batch, glycerol fed-batch, and methanol fedbatch methods to achieve high cell densities. The total cellular protein recovered after homogenization was 72 mg/g of cell paste. BoNTF(Hc) was purified from soluble Pichia cell lysate employing ion-exchange chromatographic (IEC) and hydrophobic interaction chromatographic (HIC) methods developed at the bench scale using 10–100mL columns. The process was performed at the pilot scale using 1–4 L columns for evaluation …

Environmental Management Of Waste Electrical & Electronic Equipment (Weee) In Ireland, Simon Wilkinson

Theses

This thesis follows two previous studies by the Author on the calculation of theoretical WEEE arisings, and an assessment of ecodesign practices in Ireland. It has established collection trials in five different locations throughout Ireland in order to characterise and quantify WEEE arisings, and to examine outlets for collected WEEE. Overall, during the twelve months of collection at the project locations, more than 450 tonnes of WEEE was collected from the public and recycled. Within the catchments of each facility, collection rates of between 2.1 and 3.5 kg/person/year were achieved during the twelve-month trial period. With further public awareness raising …

Extraction Of A Valuable Compound From A Waste Stream For Adm Ringaskiddy, Colin G. Burkley

Theses

This thesis was originally conceived as a potential Masters Degree research programme by the management of ADM Ringaskiddy as a means of maximizing throughput through the plant’s wastewater treatment facility. This facility is a major producer of citric acid using beet molasses and a fermentation process. It was proposed that removal of a compound, known as betaine, from the citric acid process waste stream would reduce the Chemical Oxygen Demand (COD) content of the waste requiring treatment before disposal. This would be achieved by using the citric acid process waste as the feedstock for a betaine extraction process. The wastewater …

Bubble Dynamics Measurements Using Four-Point Optical Probe, Junli Xue, Muthanna H. Al-Dahhan, M. P. Dudukovic, R. F. Mudde

Chemical and Biochemical Engineering Faculty Research & Creative Works

By Conducting an Analysis of the Measurement Errors It Was Found that Bubble Dynamics Obtained by Two-Point Probes Can Be Highly Inaccurate. a Four-Point Optical Probe with Appropriate Data Processing Algorithm Has Been Developed So that the Bubble Velocity Vector Can Be Obtained. This Probe Provides Directly the Value of Specific Gas-Liquid Interfacial Area. However, for Obtaining Accurate Values of Bubble Velocity and Size, the Four-Point Probe Must Be Calibrated by a CCD Camera at the Same Conditions. Calibration Columns Have Been Developed for This Purpose Where the Bubble Size and Velocity Can Be Varied to Calibrate the Measurements by …

Analysis Of Photobioreactors For Culturing High-Value Microalgae And Cyanobacteria Via An Advanced Diagnostic Technique: Carpt, Hu Ping Luo, Abdenour Kemoun, Muthanna H. Al-Dahhan, J. M.Fernández Sevilla, J. L.García Sánchez, F. García Camacho, E. Molina Grima

Chemical and Biochemical Engineering Faculty Research & Creative Works

Photosynthetic Algal Cultures Are a Potential Source of Many High-Value Products. in Photobioreactors (PBR), the Availability and the Intensity of the Light, Which Are Affected by the Cells' Movement, Are the Major Factors Controlling the Biomass Productivity. Hydrodynamics, Hence, Play a Significant Role in the Reactor's Performance, as They Determine Not Only the Flow Field, I.e. Liquid Flow and Mixing, Shear Stresses, Etc., But Also the Movements of the Cells. in This Work, Computer-Automated Radioactive Particle Tracking (CARPT) Technique Was Employed to Evaluate its Feasibility for Characterizing PBRs. Liquid Velocity Profiles, Cells' Movement, and the Temporal Irradiance Patterns Obtained by …

Indirect Evaporative Cooling Potential In Air-Water Systems In Temperate Climates, Ben Costelloe, Donal Finn

Articles

Recent developments have prompted a review of evaporative cooling technology as an effective means of cooling modern deep plan buildings. Prominent among these developments is the success of high temperature sensible cooling systems, particularly, chilled ceilings, which require a supply of cooling water at 14–18 °C. Crucial to the success of evaporative cooling technology, as a significant means of cooling in modern applications, is the ability to generate cooling water, in an indirect circuit, at a temperature which closely approaches the ambient adiabatic saturation temperature (AST) or wet bulb temperature (WBT). Recent experimental research has demonstrated that it is technically …

Impedance Probe To Measure Local Gas Volume Fraction And Bubble Velocity In A Bubbly Liquid, Ashok S. Sangani, R. Zenit, Donald L. Koch

Biomedical and Chemical Engineering - All Scholarship

We have developed a dual impedance-based probe that can simultaneously measure the bubble velocity and the gas volume fraction in length scales comparable to the bubble diameter. The accurate determination of the profiles is very important for comparisons with existing theories that describe the rheological behavior of bubbly liquids. The gas volume fraction is determined by the residence time of bubble within the measuring volume of the probe. We have found that the details of the bubble-probe interactions must be taken into account to obtain an accurate measure of the gas volume fraction at a point. We are able to …

Study Of Ionic Conductivity Profiles Of The Air Cathode Of A Pemfc By Ac Impedance Spectroscopy, Qingzhi Guo, Maria Cayetana, Yu-Min Tsou, Emory S. De Castro, Ralph E. White

Faculty Publications

A characterization of the ionic conduction of the active layer of a polymer electrolyte membrane fuel cell (PEMFC) cathode by ac impedance measurement at open-circuit potential conditions was conducted. Porous electrode theory was used to derive a compact equation, ∂2Φ̑2/∂y2+∂lnf(y)/∂y×∂Φ̑2/∂y−R/f(y)(1+jΩ)Φ̑2=0, to solve for the impedance response of a cathode at open-circuit potential conditions. This equation includes a parameter R, the ratio of an ionic resistance (evaluated at the active layer/membrane interface), to the total charge-transfer resistance of the active layer. The influence of an assumed ionic conductivity distribution profile f(y) on the error in the estimation of total double-layer …

Synthesis And Characterization Of Mno2-Based Mixed Oxides As Supercapacitors, Hansung Kim, Branko N. Popov

Faculty Publications

Mn/Pb and Mn/Ni mixed oxide were prepared at ambient temperature by reduction of KMnO₄ with Mn, Pb, and Ni salts. This low-temperature approach provides amorphous structure of the active material. The specific capacitance of pure MnO₂ was estimated to be 166 F/g and increased to 210 and 185 F/g for Mn/Ni and Mn/Pb oxides, respectively. The carbon loading was optimized at 20 wt %. Based on a single electrode, the Mn/Ni mixed oxide showed a high rate capability of 3.12 Wh/kg at constant power discharge of 1 kW/kg.

Corrosion Protection Of Steel Using Nonanomalous Ni-Zn-P Coatings, Basker Veeraraghavan, Bala Haran, Swaminatha P. Kumaraguru, Branko N. Popov

Faculty Publications

A novel technique for obtaining nonanomalous Ni-Zn-P coatings with high Ni content (74 wt % as compared to 15-20 wt % in the conventional plating method) has been developed. These coatings show promise as a replacement for Cd in sacrificially protecting steel. Ni-Zn-P coatings were deposited using an electroless method from a solution containing NiSO₄, complexing agent and ammonium chloride. Varying the concentration of ZnSO₄ in the bath controls the final amount of Zn in the deposit. The Zn content in the coating was optimized based on the corrosion resistance of the final deposit. Coatings with 16.2 …

Full Cell Mathematical Model Of A Mcfc, N. Subramanian, B. S. Haran, Ralph E. White, Branko N. Popov

Faculty Publications

A theoretical model for the molten carbonate fuel cell was developed based on the three-phase homogeneous approach. Using this model, the contribution of different cell components to losses in cell performance has been studied. In general, at low current densities, the electrolyte matrix contributed to the major fraction of potential losses. Mass transfer effects became important at high current densities and were more prominent at the cathode. Electrolyte conductivity and cathode exchange current density seemed to play a limiting role in determining cell performance. Using the model, the maximum power density from a single cell for different cell thicknesses was …

Thermally Stable Gel Polymer Electrolytes, Min-Kyu Song, Young-Taek Kim, Yong Tae Kim, Byung Won Cho, Branko N. Popov, Hee-Woo Rhee

Faculty Publications

To prepare miscible polyethylene glycol diacrylate/polyvinylidene fluoride (PEGDA/PVdF) blend gel polymer electrolytes, low molecular weight (M = 742) liquid PEGDA oligomer was mixed with PVdF-HFP dissolved in ethylene carbonate/dimethyl carbonate/LiPF₆ liquid electrolytes, and then cured under ultraviolet irradiation. Room temperature conductivity of PEGDA/PVdF blend films was found to be comparable to that of PVdF-HFP gel polymer electrolytes, and they were electrochemically stable up to 4.6 V vs. Li/Li⁺. Scanning electron micrographs revealed that PEGDA/PVdF blend electrolytes have pore size intermediate between dense PEGDA and highly porous PVdF-HFP. It was confirmed by weight change measurement that liquid electrolyte …

Development Of A Novel Electrochemical Method To Deposit High Corrosion Resistant Silicate Layers On Metal Substrates, Basker Veeraraghavan, Bala Haran, Dragan Slavkov, Swaminatha Prabhu, Branko N. Popov, Bob Heimann

Faculty Publications

A novel method for electrodepositing silicates on metallic substrates from aqueous solutions has been developed. The technique is demonstrated by forming a passive film on galvanized steel. The silicate layer was deposited cathodically from a bath containing PQ Corporation N sodium silicate solution (3.22 weight ratio sodium silicate, 37.5% solution in water). A post-treatment drying process increased the Si content in the coating and improved the corrosion characteristics of the silicate layer. Deposition parameters like bath concentration and temperature have been optimized using corrosion characteristics and surface morphology of the final coating. Finally, stability studies show that the silicate coatings …

Polyetheretherketone Membranes For Elevated Temperature Pemfcs, Balasubramanian Lakshmanan, Wayne Huang, David Olmeijer, John W. Weidner

Faculty Publications

Membrane electrode assemblies ~MEAs! made from polyetheretherketone ~PEEK! showed excellent fuel cell performance and thermal stability in the presence of substantial CO at elevated temperatures ~i.e., 120°C! in proton exchange membrane fuel cells ~PEMFCs!. For example, the current from a MEA made from PEEK membrane at 0.6 V and 120°C was 0.50 A/cm2 when run on pure hydrogen and 0.45 A/cm2 when run on reformate ~50% H2 , 1300 ppm CO, and balance N2). The current density from a MEA made from Nafion at 0.6 V and 120°C was 0.61 A/cm2 when run on pure hydrogen. The main difference between …

Removal Of Sustained Casing Pressure Utilizing A Workover Rig, Kevin Soter

LSU Master's Theses

This thesis will analyze the techniques used during the 1989 and 1990 workover programs as well as subsequent operations in 1991/1992. It will also present the techniques and results of the most recent 1999 workover program undertaken to alleviate the most persistent sustained casing pressure (SCP) in a mature Gulf of Mexico field. An extensive literature review is included to better illustrate the complexity of the issues involved and possible SCP mechanisms. The field was drilled during the 1980’s and SCP has been prevalent in some cases previous to initial completion operations. Previous remedial programs resulted in limited success in …

Immiscible And Miscible Gas-Oil Displacements In Porous Media, Madhav Mukund Kulkarni

LSU Master's Theses

Gas Injection is the second largest EOR process in U.S. To increase the extent of the reservoir contacted by displacing fluids, gas and water are injected intermittently - water-alternating-gas (WAG) process, is widely practiced. This experimental study is aimed at evaluating the WAG process performance in short and long cores as a function of gas-oil miscibility and brine composition. This performance evaluation has been carried out by comparing oil recoveries between WAG injection and continuous gas injection (CGI). Miscible (2500 psi) and immiscible (500 psi) floods were conducted using Berea cores, n-Decane and two different brines, namely the commonly used …

Adsorption Of Aromatic Hydrocarbons At Gas-Water Interface, Suresh Raja

LSU Master's Theses

Adsorption of organic vapors at a gas-water interface has several physical applications with respect to natural processes in the environment. Understanding the adsorption processes is critical in development of risk assessment and modeling of transport and fate of various chemical species that are abundantly present in the environment. Evidences from the works of several researchers point out deviations in gas-liquid partitioning as predicted by Henry’s law. In view of several theories that describe these deviations, adsorption process is hypothesized to be significant in gas-liquid partitioning, in addition to temperature and presence of organic matter, particularly on liquid surfaces with high …

An Experimental Study Of The Applicability Of Flooding Phenomena To The Dynamic Lubrication Method Of Well Control, Rishi R. Ramtahal

LSU Master's Theses

This research investigates the feasibility of the dynamic lubrication method of well control as an alternative to conventional stepwise lubrication. The applicability of flooding phenomena to dynamic lubrication and its use in an optimization method to maximize pumping rates was also investigated. An experimental approach was taken in which experiments were conducted in a 13’ long laboratory apparatus designed to emulate the geometry in a wellhead and also in a full-scale research well. The laboratory experiments were conducted to visually investigate the mechanism of flooding and derive a flooding correlation applicable to this type of system. The full-scale experiments were …

Forced Bubble Columns, Jia Ma

LSU Master's Theses

In many chemical, biochemical and pharmaceutical industrial processes, bubble breakage is very important for gas component to dissolve and react with surrounding liquid. The overall mass transfer performance can be improved greatly when the interfacial gas-liquid area is increased due to bubble breakup. In forced bubble columns operating at low forcing frequency (<30Hz) and small forcing amplitude (<3mm), bubbles undergo phenomenal breakage. Mass transfer coefficient, kLa, is increased to 250%~625% of the no forcing value depending on flow regime and configuration of membrane and piston. Two different mechanisms, induced shear slug breakage in the gas feeder tube for bubbly flow and resonant frequency bubble breakage in the column fluid phase for jet flow, seem to at work.

Mechanisms And Control Of Water Inflow To Wells In Gas Reservoirs With Bottom Water Drive, Miguel Armenta

LSU Doctoral Dissertations

Water inflow may cease production of gas wells, leaving a significant amount of gas in the reservoir. Conventional technologies of gas well dewatering remove water from inside the wellbore without controlling water at its source. This study addresses mechanisms of water inflow to gas wells and a new completion method to control it. In a vertical oil well, the water cone top is horizontal, but in a gas well, the gas/water interface tends to bend downwards. It could be economically possible to produce gas-water systems without water breakthrough. Non-Darcy flow effect (NDFE), vertical permeability, aquifer size, density of well perforation, …

A Novel Hydrogen And Oxygen Generation System, Zhiyong Peng

LSU Master's Theses

This study examined the three phases of the sorption-enhanced SMR process for H2 production: production of low-CO hydrogen using the standard Ni-based reforming catalyst and high purity CaO sorbent precursor, evaluation of combined reforming catalyst-sorbent samples supplied by TDA, and an Aspen simulation study of the process for simultaneous production of H2 and O2. The production of low-CO (<20ppmv) hydrogen was studied using the single-step sorption-enhanced steam methane reforming process. The effects of temperature, volumetric feed rate, and feed gas composition on the purity of H2 and the content of CO were investigated. The feasibility of producing 95+% H2 with CO content of less than 20ppmv was experimentally proven in a test at 480¡ãC and 5 atm using a commercial Ni-based catalyst and the calcium-based CO2 sorbent. The feed gas contained 20% CH4 and 80% H2O, while the product gas contained 97.8% H2 and 17 ppmv CO. With this low CO concentration, the product can be used in a proton exchange membrane (PEM) fuel cell without further purification. The catalyst-sorbent samples from TDA Research Inc. were extensively studied and evaluated with respect to their performance in the steam-reforming reaction using both the fixed-bed reactor system and TGA. The activity of the catalyst samples having different compositions was examined and compared at different temperatures and space velocities using a feed gas containing 11.1% CH4 with a steam-to-carbon (S/C) ratio of 3.0. The sorption activity and durability was also examined in the TGA system. The overall hydrogen and oxygen co-production process was studied and evaluated using the Aspen Plus simulator. Material and energy balance calculations showed that this system can produce 99+% purity hydrogen and oxygen simultaneously with efficient energy integration. This process is balanced on power consumption and generation, so no external power is required.

Bioavailability And Bioaccumulation Of Sediment-Associated, Desorption-Resistant Fraction Of Polycyclic Aromatic Hydrocarbon Contaminants, Xiaoxia Lu

LSU Doctoral Dissertations

This study is directed toward identifying and characterizing the bioavailability of both reversibly sorbed and desorption-resistant fraction of hydrophobic organic contaminants in natural biologically active sediments and the corresponding consequences to prediction, control and regulation of these contaminants. The focus is on polycyclic aromatic hydrocarbons (PAHs) with particular emphasis on phenanthrene and benzo[a]pyrene. A quantity of well-characterized and extensively desorbed sediments was prepared by desorbing the lab-inoculated sediment with an isopropanol and electrolyte solution. This procedure was proved to be a very effective method to prepare sediments containing contaminants largely limited to a desorption-resistant compartment. Accumulation of contaminants in the …

Dynamic Modeling And Parameter Estimation For An Ethlyene-Propylene-Diene Polymerization Process, Rujun Li

LSU Doctoral Dissertations

New Page 1

A general dynamic model for continuous EPDM polymerization in which crosslinking and gel formation are attributable to reactions between pendant double bonds has been developed. A pseudo-kinetic rate constant method is introduced to construct a moment model for a pseudo-homopolymer that approximates the behavior of the actual terpolymer under long chain and quasi-steady state assumptions. The pseudo-homopolymer model is then used as the basis for application of the numerical fractionation method. The proposed dynamic model is capable of predicting polydispersities and molecular weight distributions near the gel point with as few as eleven generations, and in the …

Electrodeposition Of Nickel-Copper Alloys And Nickel-Copper-Alumina Nanocomposites Into Deep Recesses For Mems, Amrit Panda

LSU Doctoral Dissertations

Electrodeposition is an important component in the fabrication of micro electro mechanical systems (MEMS). Nickel is the most commonly used material to produce three dimensional microstructures and few material alternatives have been demonstrated. In this dissertation, electrodeposited Ni-Cu alloys and nanocomposites are investigated as possible replacements for nickel in microsystems. Ni-Cu alloys are attractive for their corrosion resistance, magnetic and thermophysical properties. Alumina nanoparticulates included into metal matrices improve hardness and tribology of deposits. The Ni-Cu alloys and Ni-Cu-g-Al2O3 nanocomposites were electrodeposited from a citrate electrolyte, both at low and high pH. Electrodeposition experiments were performed in recessed microelectrodes 500 …