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(161 - 180 of 184)
Pages
- Title
- Manufacture of pure cider vinegar in the United States
- Creator
- Schommer, J. J.
- Date
- 2009, 1912
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/manufactureofpur00scho
Thesis (B.S.)--Armour Institute of Technology, 1912 B.S. in Chemical Engineering, 1912
- Title
- The manufacture of calcium cyanamide by the use of nitrogen obtained from combustion gases
- Creator
- Ford, T. Celie, Dunham, Joseph L.
- Date
- 2009, 1909
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/manufactureofcal00ford
Thesis (B.S.)--Armour Institute of Technology; Bibliography: leaf 45
- Title
- The manufacture of acetphenetidin from phenol
- Creator
- Evans, S. R, Dougherty, G. T.
- Date
- 2009, 1917
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/manufactureoface00evan
Thesis (B.S.)--Armour Institute of Technology, 1917 Bibliography: leaves 30-32 B.S. in...
Show morehttp://www.archive.org/details/manufactureoface00evan
Thesis (B.S.)--Armour Institute of Technology, 1917 Bibliography: leaves 30-32 B.S. in Chemical Engineering, 1917
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- Title
- Modern bituminous roads and pavements
- Creator
- Ford, Thomas Cecil
- Date
- 2009, 1913
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/modernbituminous00ford
Thesis (B.S.)--Armour Institute of Technology, 1913 B.S. in Chemical Engineering, 1913
- Title
- UNEQUAL GRANULAR TEMPERATURE THEORY FOR MOTION OF RED BLOOD CELLS AND PLATELETS
- Creator
- Aralaguppe Deepak Chandra, Vishak Chandra
- Date
- 2015, 2015-07
- Description
-
Blood is a multiphase mixture of liquid plasma and solid blood cells. The primary objective of this thesis is to numerically model the motion...
Show moreBlood is a multiphase mixture of liquid plasma and solid blood cells. The primary objective of this thesis is to numerically model the motion of red blood cells and platelets in blood vessels using kinetic theory based multiphase flow transport phenomena. Many experimental observations over the years have concluded that the concentration of platelets and red blood cells vary across the radius of the blood vessel. It has been shown that shear drives the platelets towards the wall, while the red blood cells move towards the center of the blood vessel. Other studies have observed that the platelet adhesion at the walls of the vessel is strongly dependent on the wall shear rate and the concentration of red blood cells. Platelet adhesion to the walls of the vessel has been explained by various shear induced diffusion models over the past few years. The diffusion models are heavily dependent on empirical relations which do not fully explain the phenomena behind the migration. In this study we postulate the dependence of red blood cell concentration on the migration of platelets using kinetic theory. The experimentally measured motion of platelets to the wall and red blood cells to the center is explained by unequal granular temperature kinetic theory. The migration of platelets in the presence of red blood cells is caused by the high granular pressure produced by the random oscillations of the red blood cells and the dissipation of platelet random energy at the walls. At the wall the shear has the highest value. This produces a high granular pressure and temperature which drive the red blood cells towards the center. An analytical solution for the platelet concentration was derived.
M.S. in Chemical Engineering, July 2015
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- Title
- The chemical utilization of municipal waste
- Creator
- Hammond, Edward K.
- Date
- 2009, 1909
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/chemicalutilizat00hamm
Thesis (B.S.)--Armour Institute of Technology
- Title
- ELECTROCHEMICAL AND TERMAL MECHANISTIC STUDY OF BEYOND LITHIUM ION SYSTEMS: LITHIUM SULFUR AND LITHIUM OXYGEN CELLS
- Creator
- Seo, Jeongwook
- Date
- 2016, 2016-05
- Description
-
Electrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of...
Show moreElectrochemical and Thermal Mechanistic Study of Lithium Sulfur Cell. The thermal behavior of Li/S cells was studied using IMC in terms of reversible and irreversible heat generation. The heat generation profile was compared with the voltage profile during discharge of the cell and it was found that the trend of heat generation rate shows excellent correlation with the evolution of reaction voltage, which demonstrates that the IMC technique can be used as an useful tool to study the elementary reactions of the Li/S cell. A simple heat generation model provides reasonable agreement with the measured trends in the heat release. The resistive heat evolution that is calculated by over voltage has the largest portion of total cell heat generation (85%) after the IMC heat evolution model analysis. The qualitative agreement between the aforementioned experimental results and heat generation model yields a comprehensive picture of the elementary reaction steps in Li/S cell. The increase of cell conductivity can be expected to bring about low heat evolution during cell cycling by reducing resistive heat. Doped Sulfur as a conductive cathode is a good suggestion to improve cell heat behavior. Furthermore, better cell cycle capability is expected by using lithium metal oxide cathode composites. The thermal behavior of three cathode materials for lithium/sulfur (Li/S) cell, namely - sulfur, sulfur-LiFePO4 (S-LFP) composite and sulfur-LiV3O8 (S-LVO) composite were comparatively studied using Isothermal Micro-Calorimetry (IMC) at various rates of discharge current. A continuum model was used to calculate the reversible entropic heat and irreversible resistive heat generated over the discharge process and the model data was compared to the experimental data to elucidate these contributions to the overall heat generated. The S-LVO composite cathode was found to show the least heat generation during discharge. Further, Accelerating Rate Calorimetry (ARC) was used to study the thermal safety of these three cells. The cell with the S-LVO composite cathode was found to have the highest onset temperature for thermal runaway and also the lowest maximum self-heat rate. The combination of high capacity, long cycle life and thermal stability makes the S-LVO composite cathode a very promising material for Li/S cells Oxygen Reduction Reaction Studies using Rotating Ring Disk Electrode for Li-Air battery. The oxygen reduction reaction (ORR) studies in aqueous electrolytes have reported the following reaction mechanisms: (i) four electron reaction, (ii) two electron reaction and (iii) one electron chemical reaction. On the other hand, the aprotic ORR literature has no reports of four electrons and two electrons transfer reaction. The kinetics of ORR on the cathode was carried out using rotating ring disk electrode (RRDE) technique. The first step of ORR which produces the superoxide radical was investigated on glassy carbon (GC) disk in 0.1 M tetrabutylammonium bis-(trifluoromethane)imide (TBATFSI)/dimethoxyethane (DME). One-electron reduction to the superoxide radical was founded in the linear sweep voltammetry (LSV) analysis. Further, ORR to produce LiO2 and Li2O2 was carried in bis(trifluoromethane)sulfonimide-lithium(LITFSI)/DME on porous carbon coated glassy carbon electrode disk. The reaction kinetic rate on the porous carbon was calculated using the Li-O2 ORR mechanism model. The kinetic rate was compared with the kinetic rate of glassy carbon electrode. The non-aqueous system has several advantages compared to the aqueous system such as high operation voltage and non-reactive electrolyte with Li+. However this system has some critical problems such as low solubility of Li2O2 and High charge over potential. One attempted solution for these disadvantages of the non-aqueous system was to carry out water addition into the solvent which was expected to produce highly soluble LiOH with lower overpotential. Small amount of Water, 0.5 wt% added into 0.1 M LiTFSI/DME and 1 wt% added in the 0.2 M TBATFSI/DME electrolyte, showed great electrochemical performance with lower onset potential and overvoltage. The kinetics of ORR study for the non-aqueous and aqueous hybrid system was carried out using RRDE technique. Koutecky-Levich plot and Tafel slope analysis indicated two electron transfer reaction on the hydrated 0.1 M LiTFSI/DME. This hydrated system can be expected to double energy storage by two electron transfer ORR for Li-O2 Cell.
Ph.D. in Chemical Engineeering, May 2016
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- Title
- Chemical analysis of engineering alloys
- Creator
- Wilsnack, G. C., Patrick, W. W
- Date
- 2009, 1912
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/chemicalanalysis00wils
Thesis (B.S.)--Armour Institute of Technology, 1912 B.S. in Chemical Engineering, 1912
- Title
- INVENTORY CREEP PHENOMENON IN PROCESS SCHEDULING
- Creator
- Aleissa, Yazeed Muqbel
- Date
- 2016, 2016-05
- Description
-
This work discuss the inventory creep phenomenon that occurs in production processes. Most production process use inventory to store their...
Show moreThis work discuss the inventory creep phenomenon that occurs in production processes. Most production process use inventory to store their products for max- imizing profit. When planning and scheduling control methods were applied, these processes encountered this phenomenon at the end of the controlled horizon. We applied the economic model protective control on a production process example and demonstrate the effect the inventory creep in open-loop and closed-loop solutions. An approach is developed to negate this problem by implementing a novel terminal constraints that showed a promising results in the overall performance of the process.
M.S. in Chemical Engineering, May 2016
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- Title
- CLONING, EXPRESSION, PURIFICATION AND STRUCTURE DETERMINATION OF PEANUT ALLERGEN ARA H 5
- Creator
- Wang, Yang
- Date
- 2012-11-21, 2012-12
- Description
-
In our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression...
Show moreIn our study, the peanut allergen Ara h 5 was cloned from raw peanut mRNA. The cDNA of the gene was then introduced into different expression vectors for protein expression in different E.coli strains. Recombinant protein expression was very successful with useful amounts of soluble protein produced. Fast protein liquid chromatography was used to purify the recombinant Ara h 5. High purity protein was subjected to crystallization screen and good quality crystals were harvested. Several crystallographic data sets were collected at a synchrotron X-ray beam line. The three-dimensional structure of the peanut profilin Ara h 5 was determined to 1.10Å resolution. The purified protein and the purification methods can be used in future research on the protein’s allergenecity, cross-reactivity and allergy immunotherapies. The high resolution structure was compared with the structures of homologous allergens and the putative epitopes was displayed on the allergen structure to evaluate their possible legitimacies. In the future, the Ara h 5 structure could be very valuable in studies of allergenecity and in the design of future immunotherapies.
PH.D in Biology, December 2012
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- Title
- THERMO-RESPONSIVE HYDROGELS FOR INTRAVITREAL INJECTION AND BIOMOLECULE RELEASE
- Creator
- Drapala, Pawel
- Date
- 2011-04-20, 2011-05
- Description
-
In this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for...
Show moreIn this dissertation, we develop an injectable polymer system to enable localized and prolonged release of therapeutic biomolecules for improved treatment of Age-Related Macular Degeneration (AMD). Thermo-responsive hydrogels derived from N-isopropylacrylamide (NIPAAm) and cross-linked with poly(ethylene glycol) (PEG) poly(L-Lactic acid) (PLLA) copolymer were synthesized via free-radical polymerization. These materials were investigated for (a) phase change behavior, (b) in-vitro degradation, (c) capacity for controlled drug delivery, and (d) biocompatibility. The volume-phase transition temperature (VPTT) of the PNIPAAm-co-PEG- b-PLLA hydrogels was adjusted using hydrophilic and hydrophobic moieties so that it is ca. 33 C. These hydrogels did not initially show evidence of degradation at 37 C due to physical cross-links of collapsed PNIPAAm. Only after addition of glutathione chain transfer agents (CTA)s to the precursor did the collapsed hydrogels become fully soluble at at 37 C. CTAs signi cantly a ected the release kinetics of biomolecules; addition of 1.0 mg/mL glutathione to 3 mM cross-linker accelerated hydrogel degradation, resulting in 100 % release in less than 2 days. This work also explored the e ect of PEGylation in order to tether biomolecules to the polymer matrix. It was demonstrated that non-site-speci c PEGylation can postpone the burst release of solutes (up to 10 days in hydrogels with 0.5 mg/mL glutathione). Cell viability assays showed that at least two 20-minute bu er extraction steps were needed to remove cytotoxic elements from the hydrogels. Clinically-used therapeutic biomolecules Lucentis® and Avastin® were demonstrated to be both stable and bioactive after release form PNIPAAm-co-PEG-b-PLLA hydrogels. The thermo-responsive hydrogels presented here o er a promising platform for the localized delivery of proteins such as recombinant antibodies.
Ph.D. in Chemical and Biological Engineering, May 2011
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- Title
- Building and operating a cider vinegar plant
- Creator
- Schommer, John Joseph
- Date
- 2009, 1920
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/buildingoperatin00scho
Thesis (B.S.)--Armour Institute of Technology
- Title
- MODELING GLUCOSE-INSULIN DYNAMICS AND AUTOMATED BLOOD GLUCOSE REGULATION IN PATIENTS WITH TYPE 1 DIABETES
- Creator
- Oruklu, Meriyan
- Date
- 2012-11-06, 2012-12
- Description
-
Estimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early...
Show moreEstimation of future glucose concentrations is a crucial task for diabetes management. Predicted glucose values can be used for early hypoglycemic/hyperglycemic alarms or for adjustment of insulin amount/rate. In the first part of this thesis, reliable subject-specific glucose concentration prediction models are developed using a patient’s continuous glucose monitoring (CGM) data. CGM technologies provide glucose readings at a high frequency and consequently detailed insight into a patient’s glucose variation. Time-series analyses are utilized to develop low-order linear models from a patient’s own CGM data. Glucose prediction models are integrated with recursive identification and change detection methods, which enable dynamical adaptation of the model to inter-/intra-subject variability and glycemic disturbances. Two separate patient data sets collected under hospitalized (disturbance-free) and normal daily life conditions are used to validate the univariate glucose prediction algorithm developed. Prediction performance is evaluated in terms of prediction error metrics and Clarke error grid analysis (CG-EGA). The long-term complications of diabetes can be reduced by controlling the blood glucose concentrations within normoglycemic limits. In the second part of this thesis, the subject-specific modeling algorithm developed in part one is integrated with a control algorithm for closing the glucose regulation loop for patients with type 1 diabetes. An adaptive control algorithm is developed to keep a patient’s glucose concentrations within normoglycemic range and dynamically respond to glycemic challenges with automated subcutaneous insulin infusion. A model-based control strategy is used to calculate the required insulin infusion rate, while the model parameters are recursively identified at each sampling step. The closed-loop algorithm is designed for the subcutaneous route for both glucose sensing and insulin delivery. xii It accounts for the slow insulin absorption from the adipose tissue and the time-delay between blood and subcutaneous glucose concentrations. The performance of the control algorithm developed is demonstrated on two simulated patient populations to provide effective blood glucose regulation in response to multiple meal challenges with a simultaneous challenge on a patient’s insulin sensitivity. Physical activity and emotional stimuli such as stress are known to have a significant effect on a patient’s whole-body fuel metabolism. In the third part of this thesis, the univariate time-series models developed from recent glucose concentration history are extended to include additional information on a patient’s physical and emotional condition. Physiological measurements from a multi-sensor body monitor are used to supplement a patient’s CGM data and develop multivariate glucose prediction models. The prediction performance of the multivariate algorithm developed is evaluated on data collected from patients with type 2 diabetes, and a real life implementation of the algorithm is demonstrated for early (i.e., 30 min in advance) hypoglycemia detection. Finally, the control algorithm developed in part two is extended to utilize the glucose profiles predicted by the multivariate patient model. The multivariate closedloop algorithm is tested with two clinical experiments performed on a patient with type 1 diabetes during a high intensity exercise followed by a carbohydrate-rich meal challenge. The algorithm acquires the patient’s CGM and armband (body monitor) data every 10 min, and accordingly calculates the required basal insulin infusion rate. Insulin is administered in a fully automated manner without any food or activity announcements (e.g., no information on meal/exercise size or time). None of the algorithms developed in this thesis require any patient specific tailoring or prior experimental data before implementation. They are also designed to function in a fully automated manner and do not require any disturbance announcexiii ments or manual inputs. Therefore, they are good candidates for installation on a portable ambulatory device used in a patient’s home environment for his/her diabetes management.
PH.D in Chemical and Biological Engineering, December 2012
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- Title
- MULTI-AGENT MODELING OF TISSUE GROWTH AND ANGIOGENESIS WITH HIGH PERFORMANCE COMPUTING
- Creator
- Bayrak, Elif Seyma
- Date
- 2015, 2015-07
- Description
-
Tissue engineering emerged as a result of the high demand of transplant organ and tissues in spite of low number of donors. Rapid and stable...
Show moreTissue engineering emerged as a result of the high demand of transplant organ and tissues in spite of low number of donors. Rapid and stable vascularization still presents the major challenge for three-dimensional functional tissues. Bone is a highly vascularized tissue. Regeneration of vascularized bone tissue from osteogenic cells in biodegradable scaffolds is strongly affected by the interplay between scaffold properties, chemical cues and precursor cells. The number of variables that contribute to the formation of engineered tissues present a challenging optimization problem that cannot be addressed with the experimentation alone. Complex system such as vascularized tissue growth can benefit from properly developed computational models. Computational models can help us understand interactions between the various parts of the complex systems, imagine all possible outcomes of a specific event, explain reasons and causes and forecast future trajectories. Agent-based modeling (ABM) is a powerful modeling and simulation technique that builds a structure from bottom-up to model and understand systems comprised of autonomous, interacting entities. ABM is a natural choice to model biological system that is comprised of many interacting cells. ABM possesses great advantages including simulating of each individuals behavior, holding their history, allowing them to adapt to dynamic conditions and learn through simple to complex algorithms. One main concern of the modelers is the computational heaviness of ABMs that limits the use of this technique in real time optimization, monitoring and control applications. Discovering the full potential of ABM in biological system with huge population size depend on the computational power available.A multi layer agent based model to simulate vascular bone regeneration in degradable porous hydrogels is developed both for personal computer (PC) environment and high performance computing (HPC) platforms. The personal computer (PC) version of this model is built upon the angiogenesis model that was previously developed by Arsun Artel and Hamidreza Mehdizadeh. This work is focused on development of bone tissue growth layer while considering the interactions and improving the existing layers and uses the parallel processing paradigm for running tissue growth more efficiently and more quickly. This model aims to help investigating and understanding the interactions between soluble factors, scaffolds and cells, and finding the optimal biomaterial structure and soluble cues to maximize vascularization and differentiation to bone tissue.
Ph.D. in Chemical Engineering, July 2015
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- Title
- By-products from wool washing
- Creator
- Butterman, Samuel, Marx, Victor E
- Date
- 2009, 1916
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/byproductsfromwo00butt
Thesis (B.S.)--Armour Institute of Technology; Includes folded leaves in back pocket
- Title
- By-products from garbage
- Creator
- Mease, A. J., Goorskey, N. J., Botts, T. E.
- Date
- 2009, 1917
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/byproductsfromga00meas
Thesis (B.S.)--Armour Institute of Technology
- Title
- MULTIFUNCTIONAL ELECTROCATALYST SUPPORTS AND ELECTROCATALYSTS FOR ELECTROCHEMICAL ENERGY CONVERSION
- Creator
- Kumar, Amod
- Date
- 2014, 2014-07
- Description
-
Polymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a...
Show morePolymer electrolyte fuel cell (PEFC) technology has several underlying problems (lifetime, reliability and cost) that need to be resolved as a prerequisite for large-scale commercialization. Amongst these, the lifetime issue is regarded as critical. From the perspective of durability, the current state-of-the-art electrocatalyst, viz. platinum (Pt) supported on high surface area carbon, suffers substantial degradation during fuel cell operation. A key pathway for electrocatalyst degradation is the corrosion of the carbon support. During fuel cell startup and shutdown in automotive applications, the cathode potential undergoes excursions of up to 1.6 V. At these high potentials, the carbon corrosion reaction is significantly accelerated, leading to irreversible carbon loss at the electrode. The best way to eliminate the issue of support corrosion in PEFCs is to develop alternate corrosion-resistant catalyst supports. This dissertation investigates (i) mixed oxides of silica (SiO2) and ruthenia (RuO2) and (ii) tantalum modified titanium oxide (Ta0.3Ti0.7O2) for use as corrosion-resistant electrocatalyst supports in PEFCs, especially for the automotive sector, using detailed microstructure characterization and electrochemical evaluation, including two carefully chosen accelerated stress tests (startstop cycling to simulate fuel cell vehicle start-up and shut-down, and load cycling to simulate full-load to no-load transitions in the vehicle during operation). RuO2–SiO2 (0.5:0.5) displayed outstanding electrochemical stability upon exposure to rigorous accelerated potential cycling tests that mimic automotive drive cycles. The Pt/RuO2–SiO2 (0.5:0.5) electrocatalyst yielded a mass activity of 50 mA/mgPt and an area specific activity of 156.3 μA/cm2 at 0.9 V vs. RHE when tested in a fuel cell operating at 80 ºC and 75% RH. A 20 wt.% Pt/Ta0.3Ti0.7O2 catalyst was compared in terms of activity and stability against benchmark Pt/C catalysts. The importance of a corrosion resistant support in a PEFC was demonstrated by monitoring performance loss during start-stop cycling and load cycling; while load cycling did not cause a performance drop, the corrosion-resistant nature of the Ta0.3Ti0.7O2 support helped prevent catastrophic fuel cell failure observed in carbon-supported catalysts during start-stop cycling. Corrosion-resistant electrode materials can not only be applied to PEFCs but can also be extended to other electrochemical energy storage and conversion devices such as redox-flow batteries and electrolyzers. The results of this work also indicate suitable strategies for incorporation of other possible dopants (such as Nb, W and Zr) within TiO2, as well as the use of other metal oxides (such as SnO2 and HfO2) as alternative catalyst supports.
Ph.D. in Chemical Engineering, July 2014
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- Title
- THE ROLE OF MOLECULAR MOTORS IN THE MECHANICS OF ACTIVE GELS AND THE EFFECTS OF INERTIA, HYDRODYNAMIC INTERACTION AND COMPRESSIBILITY IN PASSIVE MICRORHEOLOGY
- Creator
- Uribe, Andres Cordoba
- Date
- 2014, 2014-07
- Description
-
The mechanical properties of soft biological materials are essential to their physiological function and cannot easily be duplicated by...
Show moreThe mechanical properties of soft biological materials are essential to their physiological function and cannot easily be duplicated by synthetic materials. The study of the mechanical properties of biological materials has lead to the development of new rheological characterization techniques. In the technique called passive microbead rheology, the positional autocorrelation function of a micron-sized bead embedded in a viscoelastic fluid is used to infer the dynamic modulus of the fluid. Single particle microrheology is limited to fluids were the microstructure is much smaller than the size of the probe bead. To overcome this limitation in two-bead microrheology the cross-correlated thermal motion of pairs of tracer particles is used to determine the dynamic modulus. Here we present a time-domain data analysis methodology and generalized Brownian dynamics simulations to examine the effects of inertia, hydrodynamic interaction, compressibility and non-conservative forces in passive microrheology. A type of biological material that has proven specially challenging to characterize are active gels. They are formed by semiflexible polymer filaments driven by motor proteins that convert chemical energy from the hydrolysis of adenosine triphosphate (ATP) to mechanical work and motion. Active gels perform essential functions in living tissue. Here we introduce a single-chain mean-field model to describe the mechanical properties of active gels. We model the semiflexible filaments as bead-spring chains and the molecular motors are accounted for by using a mean-field approach. The level of description of the model includes the end-toend length and attachment state of the filaments, and the motor-generated forces, as stochastic state variables which evolve according to a proposed differential Chapman- Kolmogorov equation. The model allows accounting for physics that are not available in models that have been postulated on coarser levels of description. Moreover it allows the prediction of observables at time scales that will be too difficult to achieve in multi-chain simulations.
Ph.D. in Chemical Engineering, July 2014
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- Title
- STRUCTURE-PROPERTY RELATIONSHIPS IN ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE
- Creator
- Arges, Christopher George
- Date
- 2013, 2013-12
- Description
-
Polymer electrolyte membrane (PEM) fuel cells are promising candidates for powering automotive vehicles, but their advancement has been...
Show morePolymer electrolyte membrane (PEM) fuel cells are promising candidates for powering automotive vehicles, but their advancement has been hindered by the costs associated with their platinum-based electrocatalysts. One strategy to resolve this problem is to replace the conventional acidic PEM with an alkaline anion exchange membrane (AEM) because fuel cells operated in alkaline media do not require platinum group metal catalysts. A significant challenge to realizing this concept is to design and implement an AEM that is chemically robust under alkaline conditions and that facilitates high ionic conductivity. This dissertation presents a scientific approach to address the aforementioned problems through investigation of alternative cations, beyond quaternary trimethylammonium, to understand what chemical features influence ion conductivity and alkaline stability. It was postulated that selecting cations with larger free base conjugate pKA values (i.e., greater basicity) would yield improved AEM alkaline stability and ionic conductivity. The pKA value accounts for the steric hindrance, inductive, and resonance features of an organic cation and these features influence a cation’s interaction with hydroxide. Udel® polysulfone (PSF) and poly(2,6-dimethyl 1,4-phenylene) oxide (PPO) were selected as the model polymer backbones because they can be tailored with different cation groups. The types of cations assessed were of the quaternary ammonium and phosphonium types and 1-methylimidazolium. The prepared AEMs demonstrated a direct correlation between the cation’s free base conjugate pKA and anion conductivity for most cations assessed. Alkaline stability was assessed through multi-dimensional NMR to determine the degradation products in AEMs. NMR confirmed that the cation groups x xxii degraded through fundamentally different degradation mechanisms dependent upon their chemical make-up. Because the degradation mechanisms were different, the rate of degradation of the cation groups did not demonstrate a correlation to the cation’s free base conjugate pKA. If the cations did proceed through the same degradation mechanism, then a correlation was observed. Additionally, it was discovered that the cation groups in PSF and PPO triggered polymer backbone degradation in alkaline despite the resiliency of both these pristine polymers in alkaline solutions. The AEMs prepared were successfully demonstrated in several electrochemical energy storage and conversion technologies (including alkaline fuel cell, alkaline water electrolyzer, and the all-vanadium redox flow battery).
PH.D in Chemical Engineering, December 2013
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- Title
- Commercial oxidation of geraniol to geranial
- Creator
- Lyon, Arthur L
- Date
- 2009, 1920
- Publisher
- Armour Institute of Technology
- Description
-
http://www.archive.org/details/commercialoxidat00lyon
Thesis (B.S.)--Armour Institute of Technology