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Chemical Engineering

2010

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Articles 1 - 30 of 56

Full-Text Articles in Biomedical Engineering and Bioengineering

Mammary Epithelial Metastatic Phenotype Forced Through The Extracellular Matrix, Olga Shebanova Dec 2010

Mammary Epithelial Metastatic Phenotype Forced Through The Extracellular Matrix, Olga Shebanova

Publicly Accessible Penn Dissertations

Biochemical and mechanical cues of the extracellular matrix have been shown to play important roles in cell-matrix and cell-cell interactions. We have experimentally tested the combined influence of these cues on cell motility, cell-cell interaction and assembly and traction force profile in an in vitro breast cancer model. The behavior of non-tumorigenic mammary epithelial cells was observed on surfaces with varying ligand concentration and polyacrylamide gel rigidity. Our data shows that cell velocity is biphasic in both matrix rigidity and adhesiveness, which are inversely related. Traction force microscopy revealed that maximum migration velocity is reached at intermediate force of single ...


Dendritic Cell Migration And Traction Force Generation In Engineered Microenvironments, Brendon Guenther Ricart Dec 2010

Dendritic Cell Migration And Traction Force Generation In Engineered Microenvironments, Brendon Guenther Ricart

Publicly Accessible Penn Dissertations

Dendritic cells (DCs) are potent initiators of the adaptive immune response. Their trafficking from sites of inflammation to lymphoid tissue is essential to their function. Exactly how dendritic cells integrate multiple chemotactic cues to organize an accurate migratory path is not fully understood. We first characterize DC random motility (chemokinesis) on extracellular matrix proteins in the presence of chemokines. Then, using a microfluidic device, we present both single and competing chemokine gradients to murine bone-marrow derived DCs in a controlled, time-invariant microenvironment. We show that in counter gradients, CCL19 is 10 to 100 fold more potent than other chemokines CCL21 ...


Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil Nov 2010

Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil

R. Dennis Vigil

The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of Np spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can be corrected by carrying out simulations using different simulation box sizes. Specifically, the diffusion coefficient is inversely proportional to the length of a cubic simulation box, and the constant of proportionality appears to be independent of the ...


Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil Nov 2010

Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil

Chemical and Biological Engineering Publications

The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of Np spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can be corrected by carrying out simulations using different simulation box sizes. Specifically, the diffusion coefficient is inversely proportional to the length of a cubic simulation box, and the constant of proportionality appears to be independent of the ...


Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil Nov 2010

Molecular Dynamics Simulation Of Fractal Aggregate Diffusion, Gaurav Pranami, Monica H. Lamm, R. Dennis Vigil

Monica H. Lamm

The diffusion of fractal aggregates constructed with the method by Thouy and Jullien [J. Phys. A 27, 2953 (1994)] comprised of Np spherical primary particles was studied as a function of the aggregate mass and fractal dimension using molecular dynamics simulations. It is shown that finite-size effects have a strong impact on the apparent value of the diffusion coefficient (D), but these can be corrected by carrying out simulations using different simulation box sizes. Specifically, the diffusion coefficient is inversely proportional to the length of a cubic simulation box, and the constant of proportionality appears to be independent of the ...


The Conversion Of Low-Grade Heat Into Power Using Supercritical Rankine Cycles, Huijuan Chen Nov 2010

The Conversion Of Low-Grade Heat Into Power Using Supercritical Rankine Cycles, Huijuan Chen

Graduate Theses and Dissertations

Low-grade heat sources, here defined as below 300 ºC, are abundantly available as industrial waste heat, solar thermal, and geothermal, to name a few. However, they are under-exploited for conversion to power because of the low efficiency of conversion. The utilization of low-grade heat is advantageous for many reasons. Technologies that allow the efficient conversion of low-grade heat into mechanical or electrical power are very important to develop.

This work investigates the potential of supercritical Rankine cycles in the conversion of low-grade heat into power. The performance of supercritical Rankine cycles is studied using ChemCAD linked with customized excel macros ...


Thyme: A Database For Thioester-Active Enzymes, David C. Cantu, Yingfei Chen, Matthew L. Lemons, Peter J. Reilly Nov 2010

Thyme: A Database For Thioester-Active Enzymes, David C. Cantu, Yingfei Chen, Matthew L. Lemons, Peter J. Reilly

Chemical and Biological Engineering Publications

The ThYme (Thioester-active enzYme;http://www.enzyme.cbirc.iastate.edu) database has been constructed to bring together amino acid sequences and 3D (tertiary) structures of all the enzymes constituting the fatty acid synthesis and polyketide synthesis cycles. These enzymes are active on thioester-containing substrates, specifically those that are parts of the acyl-CoA synthase, acyl-CoA carboxylase, acyl transferase, ketoacyl synthase, ketoacyl reductase, hydroxyacyl dehydratase, enoyl reductase and thioesterase enzyme groups. These groups have been classified into families, members of which are similar in sequences, tertiary structures and catalytic mechanisms, implying common protein ancestry. ThYme is continually updated as sequences and tertiary ...


Plasma Mediated Molecular Delivery, Richard J. Connolly Oct 2010

Plasma Mediated Molecular Delivery, Richard J. Connolly

Graduate Theses and Dissertations

Non-viral delivery of plasmid DNA has traditionally relied upon physical forces applied directly to target tissues. These physical methods typically involve contact between an applicator and the target tissue and often cause transient patient discomfort. To overcome the contact-dependent limitations of such delivery methodologies, an atmospheric direct current plasma source was developed to deposit ionized gas molecules onto localized treatment sites. The deposition of charged species onto a treatment site can lead to the establishment of an electric field with strengths similar to those used for traditional electroporation. In vitro experiments proved that this technology could transiently permeabilize cell membranes ...


Mechanism Of Xylobiose Hydrolysis By Gh43 Β-Xylosidase, Ian J. Barker, Luis Petersen, Peter J. Reilly Oct 2010

Mechanism Of Xylobiose Hydrolysis By Gh43 Β-Xylosidase, Ian J. Barker, Luis Petersen, Peter J. Reilly

Chemical and Biological Engineering Publications

Glycoside hydrolases cleave the glycosidic linkage between two carbohydrate moieties. They are among the most efficient enzymes currently known. β-Xylosidases from glycoside hydrolase family 43 hydrolyze the nonreducing ends of xylooligomers using an inverting mechanism. Although the general mechanism and catalytic amino acid residues of β-xylosidases are known, the nature of the reaction’s transition state and the conformations adopted by the glycon xylopyranosyl ring along the reaction pathway are still elusive. In this work, the xylobiose hydrolysis reaction catalyzed by XynB3, a β-xylosidase produced byGeobacillus stearothermophilus T-6, was explicitly modeled using first-principles quantum mechanics/molecular mechanics Car−Parrinello ...


The Virtual Hip: An Anatomically Accurate Finite Element Model Based On The Visible Human Dataset, Jonathan M. Ford Oct 2010

The Virtual Hip: An Anatomically Accurate Finite Element Model Based On The Visible Human Dataset, Jonathan M. Ford

Graduate Theses and Dissertations

The purpose of this study is to determine if element decimation of a 3-D anatomical model affects the results of Finite Element Analysis (FEA). FEA has been increasingly applied to the biological and medical sciences. In order for an anatomical model to successfully run in FEA, the 3-D model’s complex geometry must be simplified, resulting in a loss of anatomical detail. The process of decimation reduces the number of elements within the structure and creates a simpler approximation of the model. Using the National Library of Medicine’s Visible Human Male dataset, a virtual 3-D representation of several structures ...


Exploring The Relationship Between Transport, Resistance, And Virulence Factors Of Escherichia Coli Collected From Swine Manure, Martha R. Zwonitzer, Michelle L. Soupir, Laura R. Jarboe Oct 2010

Exploring The Relationship Between Transport, Resistance, And Virulence Factors Of Escherichia Coli Collected From Swine Manure, Martha R. Zwonitzer, Michelle L. Soupir, Laura R. Jarboe

Agricultural and Biosystems Engineering Conference Proceedings and Presentations

Broad spectrum antibiotics, such as Tylosin (naturally synthesized by Streptomyces fradiae) are used to treat infections in farm animals and are often administered at sub-therapeutic levels along with feed rations. The presence of bacteria resistant to antimicrobials in animal waste has raised concern related to their transport to surface and groundwater. Previous studies have shown that cells preferentially attach to sediments affecting their transport in overland flow; however, a lack of quantitative understanding exists regarding the attachment mechanisms such as extracellular organelles and the relationship between these and virulence factors in humans. In a preliminary study, the presence of Tylosin ...


Investigation Of Buildup Dose For Therapeutic Intensity Modulated Photon Beams In Radiation Therapy, Khosrow Javedan Jul 2010

Investigation Of Buildup Dose For Therapeutic Intensity Modulated Photon Beams In Radiation Therapy, Khosrow Javedan

Graduate Theses and Dissertations

Buildup dose of Mega Voltage (MV) photon beams can be a limiting factor in intensitymodulated radiation therapy (IMRT) treatments. Excessive doses can cause patient discomfort and treatment interruptions, while underdosing may lead to local failure.

Many factors which contribute to buildup dose, including the photon beam energy spectrum, scattered or contaminant radiation and their angular distribution, are not modeled well in commercial treatment planning systems. The accurate Monte Carlo method was employed in the studies to estimate the doses.

Buildup dose of 6MV photon beams was investigated for three fundamentally different IMRT modalities: between Helical TomoTherapy and traditional opposed tangential ...


Three-Dimensional Atom Probe Tomography Of Oxide, Anion, And Alkanethiolate Coatings On Gold, Yi Zhang, Andrew C. Hillier Jul 2010

Three-Dimensional Atom Probe Tomography Of Oxide, Anion, And Alkanethiolate Coatings On Gold, Yi Zhang, Andrew C. Hillier

Chemical and Biological Engineering Publications

We have used three-dimensional atom probe tomography to analyze several nanometer-thick and monomolecular films on gold surfaces. High-purity gold wire was etched by electropolishing to create a sharp tip suitable for field evaporation with a radius of curvature of layer, primarily consisting of water and atmospheric gases, was observed on a fresh tip. This sample exhibited crystalline lattice spacings consistent with the interlayer spacing of {200} lattice planes of bulk gold. A thin oxide layer was created on the gold surface via plasma oxidation, and the thickness and composition of this layer was measured. Clear evidence of a nanometer-thick oxide ...


Synthesis, Characterization, And Self-Assembly Of Gold Nanorods And Nanoprisms, Kristina L. Tran Jun 2010

Synthesis, Characterization, And Self-Assembly Of Gold Nanorods And Nanoprisms, Kristina L. Tran

Graduate Theses and Dissertations

The unique properties of gold nanoparticles make them excellent candidates for applications in electronics, sensing, imaging, and photothermal therapy. Though abundant literature exists for isotropic gold nanoparticles, work on nanoparticles of different shapes has been gaining interest recently. Anisotropic gold nanoparticles, such as nanorods and nanoprisms, have tunable optical properties in the visible and near-infrared regions. Through synthesis and surface modification, the production of various shapes of these gold nanoparticles can be controlled to meet different applications.

Two different types of gold nanorods were used in this thesis. The first type was stabilized with cetyltrimethylammonium bromide (CTAB) and had aspect ...


Effects Of Monoclonal Anti-Abeta Antibodies On The Amyloid Beta Peptide Fibrillogenesis And Their Involvement In The Clearance Of Alzheimer's Disease Plaques, Jeffy Pilar Jimenez May 2010

Effects Of Monoclonal Anti-Abeta Antibodies On The Amyloid Beta Peptide Fibrillogenesis And Their Involvement In The Clearance Of Alzheimer's Disease Plaques, Jeffy Pilar Jimenez

Graduate Theses and Dissertations

Alzheimer’s disease (AD) is the most common cause of senile dementia worldwide. AD is a neurodegenerative disorder characterized by the loss of memory and language skill, collapse of the cognitive function, and distortion of social behavior. As of today, the onset mechanisms of AD and cure are unknown; however, three hallmarks are commonly encountered: extra and intracellular accumulation of amyloid beta (A!) peptide plaques, formation of intracellular neurofibrillary tangles, and inevitable neuronal death. Hypothetically, a possible scenario provoking or involved in the onset of AD is a cascade effect that starts with an imbalance in the production and clearance ...


Molecular Mechanism Of The Glycosylation Step Catalyzed By Golgi Α-Mannosidase Ii: A Qm/Mm Metadynamics Investigation, Luis Petersen, Albert Ardèvol, Carme Rovira, Peter J. Reilly May 2010

Molecular Mechanism Of The Glycosylation Step Catalyzed By Golgi Α-Mannosidase Ii: A Qm/Mm Metadynamics Investigation, Luis Petersen, Albert Ardèvol, Carme Rovira, Peter J. Reilly

Chemical and Biological Engineering Publications

Golgi α-mannosidase II (GMII), a member of glycoside hydrolase family 38, cleaves two mannosyl residues from GlcNAcMan5GlcNAc2 as part of the N-linked glycosylation pathway. To elucidate the molecular and electronic details of the reaction mechanism, in particular the conformation of the substrate at the transition state, we performed quantum mechanics/molecular mechanics metadynamics simulations of the glycosylation reaction catalyzed by GMII. The calculated free energy of activation for mannosyl glycosylation (23 kcal/mol) agrees very well with experiments, as does the conformation of the glycon mannosyl ring in the product of the glycosylation reaction (the covalent intermediate ...


Polymersomes: Multi-Functional Tools For In Vivo Cancer Theranostic Applications, Dalia H. Levine May 2010

Polymersomes: Multi-Functional Tools For In Vivo Cancer Theranostic Applications, Dalia H. Levine

Publicly Accessible Penn Dissertations

ABSTRACT

POLYMERSOMES: MULTI-FUNCTIONAL TOOLS FOR IN VIVO CANCER THERANOSTIC APPLICATIONS

Dalia Hope Levine

Dr. Daniel A. Hammer

Nanoparticles are currently being developed as delivery vehicles for therapeutic and contrast imaging agents. Polymersomes (mesoscopic polymer vesicles) possess a number of attractive biomaterial properties, including greater biocompatibility, prolonged circulation times, and increased mechanical stability, that make them ideal for these applications. The polymersome architecture, with its large hydrophilic reservoir and thick hydrophobic lamellar membrane, provides significant storage capacity for water soluble and insoluble substances.

The primary thesis aims are to develop multi-functional polymersomes for combination therapeutic applications, as well as simultaneous therapeutic ...


Comparative Studies On Oxygen Mass Transfer For The Design And Development Of A Single-Use Fermentor, Kristan L. Sorenson May 2010

Comparative Studies On Oxygen Mass Transfer For The Design And Development Of A Single-Use Fermentor, Kristan L. Sorenson

All Graduate Theses and Dissertations

Accurate experimental oxygen mass transfer coefficient, a measure of how quickly oxygen travels from a gas bubble to the bulk liquid, is important for comparing performance and for evaluating the oxygen transfer capability of a fermentor. Delays in probe response and changing gas volumes upon start-up of gassing affect the accuracy of oxygen transfer measurements. To mitigate these inaccuracies, a standard correction procedure for oxygen mass transfer data was established for highly oxygenated, well-mixed fermentation systems. Probe response time correction was generated by applying a second-order response model to dissolved oxygen probes and shown to be effective within 4%. By ...


Synthesis Of An Endothelial Cell Mimicking Surface Containing Thrombomodulin And Endothelial Protein C Receptor, Karl E. Kador Apr 2010

Synthesis Of An Endothelial Cell Mimicking Surface Containing Thrombomodulin And Endothelial Protein C Receptor, Karl E. Kador

Chemical & Biomolecular Engineering Theses, Dissertations, & Student Research

Synthetic materials for use in blood contacting applications have been studied for many years with limited success. One of the main areas of need for these materials is the design of synthetic vascular grafts for use in the hundreds of thousands of patients who have coronary artery bypass grafting, many without suitable veins for autologous grafts. The design of these grafts is constrained by two common modes of failure, the formation of intimal hyperplasia (IH) and thrombosis. IH formation has been previously linked to a mismatching of the mechanical properties of the graft and has been overcome by creating grafts ...


Nsf Engineering Research Center For Biorenewable Chemicals, Second Annual Report, Volume Ii, Nsf Engineering Research Center For Biorenewable Chemicals Apr 2010

Nsf Engineering Research Center For Biorenewable Chemicals, Second Annual Report, Volume Ii, Nsf Engineering Research Center For Biorenewable Chemicals

Center for Biorenewable Chemicals Annual Reports

In the U.S., the production of industrial chemicals is a $400 billion-plus enterprise that impacts all aspects of society from personal care products to building materials. Unfortunately, this vital industry is not self-sustaining; its long-term future is predicated on transitioning from current nonrenewable, petroleum feedstocks to renewable biobased feedstocks. The development of conversion technologies needed to facilitate this transition is the focus of the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC).


Nsf Engineering Research Center For Biorenewable Chemicals, Second Annual Report, Volume I, Nsf Engineering Research Center For Biorenewable Chemicals Apr 2010

Nsf Engineering Research Center For Biorenewable Chemicals, Second Annual Report, Volume I, Nsf Engineering Research Center For Biorenewable Chemicals

Center for Biorenewable Chemicals Annual Reports

In the U.S., the production of industrial chemicals is a $400 billion-plus enterprise that impacts all aspects of society from personal care products to building materials. Unfortunately, this vital industry is not self-sustaining; its long-term future is predicated on transitioning from current nonrenewable, petroleum feedstocks to renewable biobased feedstocks. The development of conversion technologies needed to facilitate this transition is the focus of the NSF Engineering Research Center for Biorenewable Chemicals (CBiRC).


Lipids And Collagen Matrix Restrict The Hydraulic Permeability Within The Porous Compartment Of Adult Cortical Bone, Demin Wen, Caroline Androjna, Amit Vasanji, Joanne M. Belovich, Ronald J. Midura Mar 2010

Lipids And Collagen Matrix Restrict The Hydraulic Permeability Within The Porous Compartment Of Adult Cortical Bone, Demin Wen, Caroline Androjna, Amit Vasanji, Joanne M. Belovich, Ronald J. Midura

Chemical & Biomedical Engineering Faculty Publications

In vivo the hydraulic permeability of cortical bone influences the transport of nutrients, waste products and signaling molecules, thus influencing the metabolic functions of osteocytes and osteoblasts. In the current study two hypotheses were tested: the presence of (1) lipids and (2) collagen matrix in the porous compartment of cortical bone restricts its permeability. Our approach was to measure the radial permeability of adult canine cortical bone before and after extracting lipids with acetone-methanol, and before and after digesting collagen with bacterial collagenase. Our results showed that the permeability of adult canine cortical bone was below 4.0 × 10−17 ...


Homotopy Perturbation Algorithm Using Laplace Transformation, Mohammad Madani, Mahdi Fathizade Mar 2010

Homotopy Perturbation Algorithm Using Laplace Transformation, Mohammad Madani, Mahdi Fathizade

Mohammad Madani

In this paper, a combinatory method of the Laplace transform and the homotopy perturbation method is proposed to solve non-homogeneous partial differential equations with variable coefficients. The obtained approximate solutions are compared with exact solutions and those obtained by other analytical methods, showing reliability of the present method.


Development And Characterization Of Porous And Patterned Hydrogel Scaffolds For Cardiac Muscle Tissue Engineering, Stephanie Marie Lanasa Jan 2010

Development And Characterization Of Porous And Patterned Hydrogel Scaffolds For Cardiac Muscle Tissue Engineering, Stephanie Marie Lanasa

Chemical & Biological Engineering Graduate Theses & Dissertations

Coronary heart disease has become increasingly prevalent in the U.S. and worldwide, and now affects over one million Americans annually. The damaged tissue that results from cardiac injury lacks the ability to regenerate, but no therapies exist to regenerate heart tissue. Tissue engineering is one promising method through which cardiac tissue could be regenerated. This research focuses on developing a tissue engineered hydrogel scaffold using a design regimen that facilitates nutrient transport, tensile properties, and cardiomyocyte adhesion and alignment. A porous structure incorporated into the bulk of the scaffold was selected as a means to enhance nutrient transport. Variations ...


Synthetic Peptide Design For Functionalized Hydrogels: Development Of Cellularly Responsive Drug Delivery Platforms And Cyclic, Multivalent Peptide Derivatives Using Radical-Mediated Thiol-Ene/Thiol-Yne Chemistries, Alex Arthur Aimetti Jan 2010

Synthetic Peptide Design For Functionalized Hydrogels: Development Of Cellularly Responsive Drug Delivery Platforms And Cyclic, Multivalent Peptide Derivatives Using Radical-Mediated Thiol-Ene/Thiol-Yne Chemistries, Alex Arthur Aimetti

Chemical & Biological Engineering Graduate Theses & Dissertations

Poly(ethylene glycol) (PEG)-based hydrogels represent a class of biomaterials with a growing interest for their application in numerous fields, such as drug delivery and regenerative medicine. PEG is commonly used in these applications due to its hydrophilic and bioinert properties. Additionally, peptides have been successfully incorporated within PEG hydrogels to serve as biological functionalities within a synthetic polymer platform. Peptide-functionalized PEG hydrogels have been shown to act as extracellular matrix (ECM)-mimics capable of enhancing cell survival, function, and differentiation. Alternatively, peptides can be designed to degrade in recognition of highly specific, cell-secreted proteases. This phenomenon has been ...


Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach Jan 2010

Synthesis And Characterization Of Magnetic Hydrogel Nanocomposites For Cancer Therapy Applications, Samantha Ann Meenach

University of Kentucky Doctoral Dissertations

Currently, cancer is the second leading cause of death in the United States. Conventional cancer treatment includes chemotherapy, radiation, and surgical resection, but unfortunately, all of these methods have significant drawbacks. Hyperthermia, the heating of cancerous tissues to between 41 and 45°C, has been shown to improve the efficacy of cancer therapy when used in conjunction with irradiation and/or chemotherapy. In this work, a novel method for remotely administering heat is presented. This method involves heating of tumor tissue using hydrogel nanocomposites containing magnetic nanoparticles which can be remotely heated upon exposure to an external alternating magnetic field ...


Sensing Polymer/Dna Polyplex Dissociation Using Quantum Dot Fluorophores, Bingqi Zhang, Yanjie Zhang, Surya K. Mallapragada, Aaron R. Clapp Jan 2010

Sensing Polymer/Dna Polyplex Dissociation Using Quantum Dot Fluorophores, Bingqi Zhang, Yanjie Zhang, Surya K. Mallapragada, Aaron R. Clapp

Chemical and Biological Engineering Publications

We characterized the dissociation of polymer/DNA polyplexes designed for gene delivery using water-soluble quantum dots (QDs). A pH-responsive pentablock copolymer was designed to form stable complexes with plasmid DNA via tertiary amine segments. Dissociation of the polyplex was induced using chloroquine where the efficiency of this process was sensed through changes in QD fluorescence. We found that increasing concentrations of pentablock copolymer and DNA led to quenching of QD fluorescence, while chloroquine alone had no measurable effect. The mechanism of quenching was elucidated by modeling the process as the combination of static and dynamic quenching from the pentablock copolymer ...


Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler Jan 2010

Reversible Addition - Fragmentation Chain Transfer In Microemulsions: Effect Of Chain Transfer Agent Aqueous Solubility, Jennifer M. O'Donnell, Eric W. Kaler

Jennifer M. Heinen

Microemulsion polymerizations are attractive for investigating compartmentalization effects in heterogeneous reversible addition - fragmentation chain transfer (RAFT) polymerizations because the propagating radicals are segregated into surfactant stabilized polymer particles, which drastically reduces the effects of biradical termination, Also, microemulsion polymerizations do not involve the large monomer droplets that are present in emulsion and miniemulsion polymerizations. RAFT microemulsion polymerizations of butyl aery late with a high water solubility chain transfer agent, methyl-2-(O-ethylxanthyl)propionate (MOEP), and a low water solubility chain transfer agent, methyl-2-(O-dodecylxanthyl)propionate (MODP), were investigated to determine the effect of chain transfer agent compartmentalization on the control of ...


Catalytic Strategies Of Glycoside Hydrolases, Luis Petersen Jan 2010

Catalytic Strategies Of Glycoside Hydrolases, Luis Petersen

Graduate Theses and Dissertations

Glycoside hydrolases (GHs) are enzymes that catalyze the hydrolysis of the glycosidic bond between two carbohydrate residues or a carbohydrate unit linked to a non-carbohydrate aglycon unit. Despite years of research dedicated to GHs, there are still several mechanistic details, relevant for individual GH enzymes, that remain to be investigated. In this work, a computational analysis of the detailed mechanism of several GHs is presented. QM/MM metadynamics simulations of two glycoside hydrolases, GH8 endoglucanase and GH43 β-xylosidase, give insight into the enzymatic deconstruction of the plant cell wall, and the detailed reaction mechanism of both enzymes. In addition, an ...


Alternative Routes For Purification Of Collagen Type I Α1 From A Whole Corn Extract, Christopher Michael Setina Jan 2010

Alternative Routes For Purification Of Collagen Type I Α1 From A Whole Corn Extract, Christopher Michael Setina

Graduate Theses and Dissertations

Transgenic corn is capable of producing and storing Type I α1 human collagen (r-CIα1) containing a sequence that assists assembly (foldon) and the mature cleaved form (without foldon). Extracts of ground corn grain spiked with Pichia-sourced collagen (rP-CIα1), with and without foldon, were precipitated with NaCl to purify collagen from host cell proteins. The low acid solubility of host cell proteins (HCP's) along with the acid stability of collagen favored extraction at pH 2. NaCl concentrations >0.75 M provided complete precipitation of rP-CIα1 without foldon and >70% purity. A fractional cut to remove HCP's with 0 ...