Chemical Engineering Commons^™

Polysaccharide-Based Shear Thinning Hydrogels For Three-Dimensional Cell Culture, Vasudha Surampudi

Theses and Dissertations

The recreation of the complicated tissue microenvironment is essential to reduce the gap between in vitro and in vivo research. Polysaccharide-based hydrogels form excellent scaffolds to allow for three-dimensional cell culture owing to the favorable properties such as capability to absorb large amount of water when immersed in biological fluids, ability to form “smart hydrogels” by being shear-thinning and thixotropic, and eliciting minimum immunological response from the host. In this study, the biodegradable shear-thinning polysaccharide, gellan-gum based hydrogel was investigated for the conditions and concentrations in which it can be applied for the adhesion, propagation and assembly of different mammalian …

Fabrication Of Tissue Precursors Induced By Shape-Changing Hydrogels, Olukemi O. Akintewe

USF Tampa Graduate Theses and Dissertations

Scaffold based tissue reconstruction inherently limits regenerative capacity due to inflammatory response and limited cell migration. In contrast, scaffold-free methods promise formation of functional tissues with both reduced adverse host reactions and enhanced integration. Cell-sheet engineering is a well-known bottom-up tissue engineering approach that allows the release of intact cell sheet from a temperature responsive polymer such as poly-N-isopropylacrylamide (pNIPAAm). pNIPAAm is an ideal template for culturing cell sheets because it undergoes a sharp volume-phase transition owing to the hydrophilic and hydrophobic interaction around its lower critical solution temperature (LCST) of 32°C, a temperature close to physiological temperature. Compared to …

Silicone Elastomer-Based Combinatorial Biomaterial Gradients For High Throughput Screening Of Cell-Substrate Interactions, Greeshma Mohan

USF Tampa Graduate Theses and Dissertations

Biomaterials have evolved over the years from the passive role of mere biocompatibility to an increasingly active role of presenting instructive cues to elicit precise responses at the molecular and cellular levels. Various characteristics common to synthetic biomaterials in vitro and extracellular matrices in vivo, such as immobilized functional or peptide groups, mechanical stiffness, bulk physical properties and topographical features, are key players that regulate cell response. The dynamics in the cell microenvironment and at the cell adhesive interface trigger a web of cell-material and cell-cell information exchanges that have a profound impact in directing the ultimate cell fate …

Additives For Heat Transfer Enhancement In High Temperature Thermal Energy Storage Media: Selection And Characterization, Philip D. Myers Jr.

USF Tampa Graduate Theses and Dissertations

Inorganic salts are very promising as high-temperature heat transfer fluids and thermal storage media in solar thermal power production. The dual-tank molten salt storage system, for example, has been demonstrated to be effective for continuous operation in solar power tower plants. In this particular storage regime, however, much of the thermal storage potential of the salts is ignored. Most inorganic salts are characterized by high heats of fusion, so their use as phase-change materials (PCMs) allows for substantially higher energy storage density than their use as sensible heat storage alone. For instance, use of molten sodium-potassium eutectic salt over a …

Steam Gasification Rates Of Three Bituminous Coal Chars In An Entrained-Flow Reactor At Pressurized Conditions, Aaron D. Lewis, Troy M. Holland, Nathaniel R. Marchant, Emmett G. Fletcher, Danley J. Henley, Eric G. Fuller, Thomas H. Fletcher

Faculty Publications

Three bituminous coal chars (Illinois #6, Utah Skyline, and Pittsburgh #8) were gasified separately at total pressures of 10 and 15 atm in an entrained-flow reactor using gas temperatures up to 1830 K and particle residence times gasification, although select experiments were performed at conditions where significant mass release was due to gasification by both H2O and CO2. The measured coal data were fit to three char gasification models including a simple first-order global model, as well as the CCKN and CCK models that stem from the CBK model. The optimal kinetic parameters for each of the three models are …

Model For The Evolution Of Pore Structure In A Lignite Particle During Pyrolysis, Sufen Li, He Yang, Thomas H. Fletcher, Ming Dong

Faculty Publications

In this paper, on the basis of the chemical percolation devolatilization (CPD) model and using the coal polymer network parameters to calculate the surface area and porosity of the particle, a model for the evolution of pore structure in a lignite particle during pyrolysis is established. The model connects the polymer network structure and the pore structure, and it may extend the application range of network statistical devolatilization models. Model predictions agree with experimentally observed trends reported in the literature for porosity and internal surface area with increasing mass release. Particle porosity increases during pyrolysis because of mass release and …

Fuel Element Combustion Properties For Live Wildland Utah Shrubs, Thomas H. Fletcher, Chen Shen

Faculty Publications

Current field models for wildfire prediction are mostly based on dry or low-moisture fuel combustion research. To better study the live fuel combustion behavior, a laminar flow flat-flame burner was used to provide a convection heating source to ignite an individual live fuel sample. In this research project, four Utah species were studied: Gambel oak (Quercus gambelii), canyon maple (Acer grandidentatum), big sagebrush (Artemisia tridentata), and Utah juniper (Juniperus osteosperma). Leaf geometrical parameters measured included individual leaf total mass, thickness, leaf width, leaf length, and moisture content. Time-stamped images of combustion behavior along with time-dependent mass data were recorded via …

Stabilizing Electrochemical Carbon Capture Membrane With Al2O3 Thin-Film Overcoating Synthesized By Chemical Vapor Deposition, Jingjing Tong, Fengzhan Si, Lingling Zhang, Jie Fang, Minfang Han, Kevin Huang

Faculty Publications

Development of high-efficiency and cost-effective carbon capture technology is a central element of our effort to battle the global warming and climate change. Here we report that the unique high-flux and high-selectivity of electrochemical silver-carbonate dual-phase membranes can be retained for an extended period of operation by overcoating the surfaces of porous silver matrix with a uniform layer of Al₂O₃ thin-film derived from chemical vapor deposition.

Integration Of Human And Organizational Factors With Quantitative Risk Assessment Based On Accident Investigation, M. Ahmad, Marco Pontiggia, Maria Chiara Leva

Conference Papers

This paper presents a statistical analysis of past accidents that occurred between 1988 and 2012 reported to the European Commission’s Major Accident Reporting System (eMARS) focusing on Human and Organizational Factors (HOF). The main purpose of this work is to quantify the HOF integrated with conventional risk assessment approaches and to provide future guidelines to relevant standards and current best practices. The accident analysis results are further used to quantify the HOF assessment based on the probabilistic Rasch model. A new approach, Method for Error Deduction and Incident Analysis (MEDIA) is proposed which can be used with Quantitative Risk Assessment …

Aqueous Atmospheric Species, A Dual Study: 1. Comparison Of The Effects Of Temperature, Oxygen Level, Ionic Strength, And Ph On The Reaction Of Benzene With Hydroxyl Radicals At The Air-Water Interface To The Bulk Aqueous Phase. 2. Determination Of Carbonyl Compounds In Fog Water Samples Via Online Concentration And Hplc, Aubrey Anne Heath

LSU Doctoral Dissertations

The air-water interface is the largest interface in the environment. Atmospheric droplets, such as fog, which can have an exceptionally high surface area-to-volume ratio, also have a large range of physical and chemical properties (e.g. temperature, pH, ionic strength, and chemical composition) based on location, time of day, and emission source. Unlike larger atmospheric droplets, which are predominately characterized by bulk aqueous phase conditions, reactions that take place in fog droplets are determined by both the bulk-aqueous phase and the air-water interface due to a high surface area-to-volume ratio. In order to have a greater understanding of atmospheric processes and …

Catalysts For The Positional Isomerization Of Internal, Long-Chain Olefins, James Edward Bruno

LSU Doctoral Dissertations

Double-bond isomerization of internal C16-C18 olefins is a necessary step in the production of paper sizing agents. In this work, the properties that enable long-lasting solid acid catalysts (both commercial and lab-synthesized) were identified, the efficacy of regenerated solid acid catalysts was tested, and the feasibility of organometallic chain-walking catalysts (both homogeneous and polymer-supported) for olefin isomerization was evaluated. Hexadecene isomerization was investigated using perfluorinated ion exchange resins (Nafion®) supported on SiO2 or Al2O3, sulfonated poly(styrene-co-divinylbenzene) resins (PS-DVBs), tungstated zirconias, and acidic zeolites. Selected catalysts underwent lifetime studies. Oversulfonated PS-DVBs (e.g., Amberlyst 35) were reasonably selective with long lifetimes, only …

A Fast Approach For Preparation Of Adsorbent From Reed Black Liquor And Its Performance In Equilibrium And Kinetic Gas Separation, G. Yang, Yong Sun, C. Wen, J. Zhang

Research outputs 2014 to 2021

A new approach using reed pulping black liquor by hydrothermal reaction followed by fast carbonization at 350 °C in fluidized bed reactor for 5 minutes was proposed in this paper. The BET specific surface area generated at optimum conditions reached 390 m2 g–1. The CO2 selectivity over CH4 and N2 comparable to commercial activated carbons was obtained. The isosteric enthalpies of adsorption for CO2, CH4 and N2 on the resultant carbon sample prepared at optimum conditions show surface heterogeneity. The kinetic results indicate its potential for separation of carbon dioxide from carbon dioxide/methane mixture.

Mechanistic Models On Enzymatic Hydrolysis And Anaerobic Digestion, Yang Zhang

Dissertations, Master's Theses and Master's Reports

For enzymatic hydrolysis, a mechanistic model on enzymatic hydrolysis of pure cellulosic substrates was improved to consider oligomer reactions with beta-glucanases, inhibition of oligomers to cellulases and enzyme decay. Then a novel and general modeling framework was developed for enzymatic hydrolysis of hemicellulose-cellulosic substrates. This mechanistic model, for the first time, took into consideration explicitly the time evolution of morphologies of intertwining cellulose and hemicelluloses. This novel mechanistic model was applied to optimize the composition of enzyme mixtures for substrate conversion and monosaccharides yield during simultaneous enzymatic hydrolysis of different lignocellulosic substrates. For anaerobic digestion, the original "Anaerobic Digestion Model …

Selective Synthesis And Characterization Of Single-Site Hy Zeolite-Supported Rhodium Complexes And Their Use As Catalysts For Ethylene Hydrogenation And Dimerization, Konstantin Khivantsev

Theses and Dissertations

Single-site Rh(CO)2, Rh(C2H4)2 and Rh(NO)2 complexes anchored on various dealuminated HY zeolites can be used as precursors for the selective surface mediated synthesis of well-defined site-isolated Rh(CO)(H)x complexes. DFT calculations and D2 isotope exchange experiments provide strong evidence for the formation of a family of site isolated mononuclear rhodium carbonyl hydride complexes (including the first examples of RhH complexes with undissociated H2 ligands): Rh(CO)(H2), Rh(CO)(H)2, and Rh(CO)(H). The fraction of each individual complex formed varies significantly with the Si/Al ratio of the zeolite and the nature of the precursor used.

HY zeolite-supported mononuclear Rh(CO)2 complexes are remarkably active in ethylene …

Engineered 3d Microenvironments To Direct Osteogenic Differentiation And Modulate Inflammation, Katherine Elizabeth Rutledge

Theses and Dissertations

Current methods of treating critical size bone defects (CSDs) include autografts and allografts, however both present major limitations including donor-site morbidity, risk of disease transmission, and immune-rejection. Tissue engineering provides a promising alternative to circumvent these shortcomings through the use of stem cells, three dimensional (3D) scaffolds, and growth factors. Cells receive signals from their microenvironment that determine cell phenotype, and a combination of physical cues and chemical factors is thought to have the most profound influence on stem cell behavior. A major focus of tissue engineering strategies is scaffold design to recapitulate in vivo microenvironmental architecture to direct stem …

Energy Intensity And Environmental Impact Metrics Of The Back-End Separation Of Ethylene Plant By Thermodynamic Analysis, Mahdi H. Alhajji, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: Faculty Publications

This study presents metrics of energy intensity and environmental impact of the back-end separation of ethylene plant consisting three interacting distillation columns by thermodynamic analysis. The objective is to explore the scope of reducing the energy for utilities and CO₂ emissions. Thermodynamic analysis is carried out using the column targeting tool (CTT) to address the sustainability metrics of ‘Energy Intensity.’ CTT is based on the ‘Practical Near-Minimum Thermodynamic Condition’ representing a close to practical reversible column operation. Environmental impact metrics are estimated from the carbon tracking options. The carbon tracking are estimated by the CO₂ emission data source …

Chemical Storage Of Wind Energy By Renewable Methanol Production: Feasibility Analysis Using A Multi-Criteria Decision Matrix, Michael J. Matzen, Mahdi H. Alhajji, Yaşar Demirel

Department of Chemical and Biomolecular Engineering: Faculty Publications

This study is for the technoeconomic analysis of an integral facility consisting of wind energy-based electrolytic hydrogen production, bioethanol-based carbon dioxide capture and compression, and direct methanol synthesis. ASPEN Plus was used to simulate the facility producing 97.01 mt (metric tons) methanol/day using 138.37 mt CO₂/day and 18.56 mt H₂/day. A discounted cash flow diagram for the integral facility is used for the economic analysis at various hydrogen production costs and methanol selling prices. The feasibility analysis is based on a multi-criteria decision matrix consisting of economic and sustainability indicators comparing renewable and non-renewable methanol productions. …

Cell Infiltration Into A 3d Electrospun Fiber And Hydrogel Hybrid Scaffold Implanted In The Brain, Christopher J. Rivet, Kun Zhou, Ryan J. Gilbert, David I. Finkelstein, John S. Forsythe

Chemical and Biochemical Engineering Faculty Research & Creative Works

Tissue engineering scaffolds are often designed without appropriate consideration for the translational potential of the material. Solid scaffolds implanted into central nervous system (CNS) tissue to promote regeneration may require tissue resection to accommodate implantation. Or alternatively, the solid scaffold may be cut or shaped to better fit an irregular injury geometry, but some features of the augmented scaffold may fail to integrate with surrounding tissue reducing regeneration potential. To create a biomaterial able to completely fill the irregular geometry of CNS injury and yet still provide sufficient cell migratory cues, an injectable, hybrid scaffold was created to present the …

Investigation Of Lost Circulation Materials Impact On Fracture Gradient, Mortadha Turki Alsaba

Doctoral Dissertations

"Lost circulation is a challenging problem to be prevented or mitigated during drilling. Lost circulation treatments are widely applied to mitigate losses using a corrective approach or to prevent losses using preventive approaches, also known as "wellbore strengthening". The disagreement among the different wellbore strengthening theories and the lack of understanding the strengthening mechanism resulted in the absence of a standardized method to evaluate the effectiveness of lost circulation materials (LCM) for wellbore strengthening application.

An extensive experimental investigation was performed by constructing a high pressure LCM test apparatus to investigate the effects of different parameters on the sealing efficiency …

Thermo-Catalytic Methane Decomposition: A Review Of State Of The Art Of Catalysts, Ahmed A. Ibrahim, Ahmed S. Al-Fatesh, Wasim Ullah Khan, Moustafa A. Soliman, Raja L. Al-Otaibi, Anis H. Fakeeha

Chemical Engineering

The catalytic methane decomposition to produce carbon oxides–free hydrogen and carbon nanomaterial is a promising method feasible for larger production at a moderate cheap price. The produced hydrogen is refined and can be employed straight in fuel cell and in petrochemical industries to produce ammonia and methanol. Auto-thermal reforming of natural gas, partial oxidation, steam reforming are the conventional techniques for hydrogen production in industry, though these processes incur excessive costs for the purification of hydrogen from producing carbon oxides. Current research work on thermo-catalytic methane decomposition has concentrated on promoting the catalytic activity and stability for simultaneous production of …