Chemistry Commons^™

Experimental And Simulation Study Of Reactive Silver Ink Droplet Evaporation, Weipeng Zhang

Electronic Thesis and Dissertation Repository

The evaporation of particle-free silver ink droplets on heated substrates directly impacts the morphology of the resultant silver particles and films. In this thesis, COMSOL Multiphysics simulations of the solvent (water-ethylene glycol mixture) droplet evaporation process are used to explain the microflows, mass transfers, and heat distribution responsible for the experimental observations. The reactive ink incorporates fluoro-surfactant FS-31 and poly (acrylamide) (PAM) to suppress the coffee-ring effect that negatively impacts the electrical conductivity. Experiments show that the droplet evaporation process results in varied silver particle morphology, depending on the locations within the droplet, leading to uneven surfaces. Large particles (3 …

Application Of Crystal Engineering In Multicomponent Pharmaceutical Crystals: A Study Of Theory And Practice, Soroush Ahmadi Nasrabadi

Electronic Thesis and Dissertation Repository

Multicomponent crystallization, a prominent strategy in crystal engineering, offers the ability to modify the physicochemical properties of crystals by introducing a secondary component to their lattice structure. Such multicomponent crystals have found widespread application in the pharmaceutical industry. This thesis explores the experimental screening, characterization, application, and theoretical prediction of multicomponent crystals of Active Pharmaceutical Ingredients (APIs).

The first case study investigates a new solvate of Dasatinib which exhibits high instability at room temperature and transforms into a different polymorph upon desolvation. The crystal structure of this compound is obtained, revealing insights into its transient nature and the potential application …

Progress Toward Durable Icephobic Materials, Matthew J. Coady

Electronic Thesis and Dissertation Repository

Ice accumulation is a major engineering challenge in many fields including aerospace, power generation, transportation, and infrastructure. A variety of solutions are being researched to address this challenge. Perhaps the most promising method of combating ice accumulation is by applying coatings with low values of interfacial ice adhesion strength, τ_ice. Icephobic materials are those with ice adhesion below 100 kPa, and it has been shown that passive delamination can occur on surfaces with τ_ice below 20 kPa. While various low adhesion surfaces have been prepared, durability concerns pervade applications where surfaces experience repeated icing or freeze-thaw cycles, …

Plant Stimuli-Responsive Biodegradable Polymers For The Use In Timed Release Fertilizer Coatings, Spencer Heuchan

Electronic Thesis and Dissertation Repository

The use of nitrogen-based fertilizers continues to accelerate with human population growth and increases in global food requirements. Enhanced efficiency fertilizers (EEFs) have been developed to improve the synchronization between nutrient supply and crop nutrient demand. However, many of the current controlled release fertilizers are coated with non-degradable polymers that contribute to accumulation of microplastics within ecosystems. This thesis describes research towards the development of a new class of fertilizer coatings using a self-immolative polymer known as poly (ethyl glyoxylate) (PEtG). PEtG itself does not have suitable properties to produce a viable coating but once blended with another degradable polyester …

Study On The Surface Features Of Preg-Robbing Carbonaceous Matter During Oxidation Treatment, Mana Pourdasht

Electronic Thesis and Dissertation Repository

Carbonaceous gold ores have the ability to adsorb gold (I) cyanide from leach solutions during processing. This phenomenon, known as preg-robbing, is responsible for poor recoveries as the carbonaceous materials of the ore compete with activated carbon used during the leaching and adsorption phase of processing. Chemical oxidation of carbonaceous materials by different reagents has been utilized to investigate and compare the mechanism of Au (CN)₂ adsorption onto carbonaceous materials prior to and following the treatment.

The procedure for characterization of the carbonaceous materials (plain and modified) in the sample combines the use of several analytical techniques and test …

Fabrication And Modification Of Titania Nanotube Arrays For Harvesting Solar Energy And Drug Delivery Applications, Ahmed El Ruby Abdel Rahman Mohamed

Electronic Thesis and Dissertation Repository

The fast diminishing of fossil fuels in the near future, as well as the global warming caused by increasing greenhouse gases have motivated the urgent quest to develop advanced materials as cost-effective photoanodes for solar light harvesting and many other photocatalytic applications. Recently, titania nanotube arrays (TNTAs) fabricated by anodization process has attracted great interest due to their excellent properties such as: high surface area, vertically oriented, highly organized, one-dimensional, nanotubular structure, photoactivity, chemical stability and biocompatibility. This unique combination of excellent properties makes TNTAs an excellent photoanode for solar light harvesting. However, the relatively wide band gap energy of …

Crystal Engineering Of Active Pharmaceutical Ingredients With Low Aqueous Solubility And Bioavailability, Jenna M. Skieneh

Electronic Thesis and Dissertation Repository

Approximately 75% of new molecular entities approved by the Food and Drug Administration (FDA) for use in the pharmaceutical industry are found to have poor aqueous solubility. This undesirable attribute leads to consequences such as higher doses required to reach therapeutic levels, greater vulnerability to food effects, lesser fraction absorbed in the small intestine and damage to the environment due to increased quantity of excretion. The addition of an excipient (i.e. a FDA approved inactive ingredient) to the molecular structure of an active pharmaceutical ingredient (API) through intermolecular bonding is of growing interest because the properties of the API can …

Mechanism Of Ethanol Partial Oxidation Over Titania Supported Vanadia Catalysts: Geometric And Electronic Structure Consequences On Reaction Kinetics, Dongmin Yun

Electronic Thesis and Dissertation Repository

Supported vanadium oxide catalysts (VO_x) are used for a wide range of industrial processes. A significant amount of research has been carried on this specific system with the aim to identify the critical parameters involved in catalytic activity. The results on this relative large body of research indicate that the catalyst support plays a critical role in determining the catalytic activity of vanadia and the use of titanium dioxide as support renders a catalyst with superior activity. Studies on supported vanadia on titanium oxide (VO_x/TiO₂) have provided an understanding on support interactions that result …

Doped Tio2 Nanowires For Applications In Dye Sensitized Solar Cells And Sacrifical Hydrogen Production, Qasem Alsharari

Electronic Thesis and Dissertation Repository

This thesis explores the synthesis of metal oxide 1-D nanowires using a sol-gel method in supercritical carbon dioxide (sc-CO₂), as an environmental friendly enabling solvent. Porous nanowires were synthesized and their performance was tested in dye sensitized solar cell and sacrifical hydrogen production. Titanium isopropoxide (TIP) was used as a precursor for titania synthesis while copper, bismuth and indium were examined as dopants, respectively. The sol-gel reactions were catalyzed by acetic acid in CO₂ at a temperature of 60 °C and pressure of 5000 psi. It was observed that acetic acid/monomer ratio > 4 produced nanowires while a …

Production And Applications Of Formaldehyde-Free Phenolic Resins Using 5-Hydroxymethylfurfural Derived From Glucose In-Situ, Yongsheng Zhang

Electronic Thesis and Dissertation Repository

The phenol-formaldehyde (PF) resin manufacturing industry is facing a growing challenge with respect to concerns over human health, due to the use of carcinogenic formaldehyde and sustainability due to the use of petroleum-based phenol in PF resin manufacture. Glucose and its derivative, 5-hydroxymethylfurfural (5-HMF), have proven to be potential substitutes for formaldehyde in the synthesis of phenolic novolac resins.

This thesis investigated a number of glucose and 5-HMF resin systems including the curing of phenol-glucose novolac resin (PG) with a bis-phenol-A type epoxy. The curing process was modeled according to the Sestak-Berggren equation (S, B) using Málek methods. This was …

Poly(Ester Amide) And Poly(Ethyl Glyoxylate) Nanoparticles For Controlled Drug Release, Amira Mohamed Moustafa

Electronic Thesis and Dissertation Repository

The objective of this research was to develop polymeric nanoparticles (NPs) having improved drug release properties for drug delivery. Poly(ester amide)s (PEAs) are promising biodegradable polymers. PEA NPs were prepared via emulsification-evaporation and salting-out methods and optimized through by varying different processing parameters. Polymer-model drug conjugates based on PEAs containing L-aspartic acid and rhodamine B were synthesized and used for NP preparation. Release behavior was studied and compared to a control system with physically encapsulated rhodamine B. It was shown that the release of rhodamine B from the covalent system did not show the burst effect and exhibited a slower …

Scale-Up Methodology For Bench-Scale Slurry Photocatalytic Reactors Using Combined Irradiation And Kinetic Modelling, Patricio J. Valades Pelayo

Electronic Thesis and Dissertation Repository

The present study focuses on developing a predictive methodology to scale-up a slurry annular photoreactor using a TiO₂ Degussa P25 from the bench-scale to a pilot-plant scale. The bench-scale photoreactor is a Photo-CREC-Water II, a 2.65 L internally-irradiated slurry annular photocatalytic reactor. The pilot-plant scale photoreactor is a Photo-CREC Water Solar Simulator, a 9.8 L pilot-plant photoreactor, externally irradiated by eight lamps.

The adopted methodology allows the independent validation of radiative and kinetic models avoiding cross-correlation issues. The proposed approach involves two Monte Carlo methods, to model the Radiative Transfer Equation (RTE) inside each photoreactor. With this end, a …

Diffusion And Adsorption Coefficients Of Aromatic Hydrocarbons In Gas Chromatography Capillary Columns, Gabriela Navarro Tovar

Electronic Thesis and Dissertation Repository

This study focuses on a mathematical description of aromatic species elution peaks from a gas chromatographic BPX5 capillary column. Using the chromatographic peaks, statistical moments are calculated for toluene, naphthalene, phenol and 2-naphthol. This thesis reports two modelling approaches involving laminar gas flow, distribution coefficients (K_s) and diffusion coefficients in the stationary phase (D_s).

Firstly, a model with equilibrium adsorption is considered to describe symmetric peaks for toluene and naphthalene. Moreover, a model with non-equilibrium adsorption is proposed to describe asymmetric peaks of phenol and 2-napthol. In addition to the K_s and D …

Surface Functionalization And Bioconjugation Of Nanoparticles For Biomedical Applications, Longyan Chen

Electronic Thesis and Dissertation Repository

Colloidal inorganic nanoparticles (NPs) have been attracting considerable interest in biomedicine, from drug and gene delivery to imaging, sensing and diagnostics. It is essential to modify the surface of nanoparticles to have enhanced biocompatibility and functionality for the in vitro and in vivo applications, especially in delivering locally and recognizing biomolecules. Herein, the goal of this research work is to develop advanced NPs with well-tailored surface functionalities and/or bio-functionality for the applications in cell tracking and analytes detection.

In the first project, quantum dots incorporating with gelatin nanoparticles (QDs-GNPs) have been developed for bioimaging applications. Two different approaches have been …

Degradation Kinetics And Functional Design Of Linear Self-Immolative Polymers, Ryan A. Mcbride

Electronic Thesis and Dissertation Repository

Linear self-immolative polymers display a potential to address many of the limitations in the control over the degradation process in traditional biodegradable polymers. These materials are unique relative to most degradable 
polymers, in that they undergo end-to-end depolymerization in
 response to the cleavage of a stabilizing end-capping agent. Although one of their cited 
attributes is a dependence of their degradation time on chain length, no conclusive study has been conducted to demonstrate and study this 
effect. Using a previously reported linear self-immolative backbone derived from alternating 4-hydroxybenzyl alcohol and N,N’-dimethylethylenediamine spacers, this work offers the first conclusive study demonstrating …

Butyl Rubber-Aliphatic Polyester Graft Copolymers For Biomedical Applications: Synthesis And Analysis Of Chemical, Physical And Biological Properties, Bethany A. Turowec

Electronic Thesis and Dissertation Repository

Biomaterials can be used in a wide variety of medical applications owing to their breadth of characteristics that can be imparted by varying their chemical structures. Butyl rubber (IIR), which is a copolymer of isobutylene (IB) and small percentages of isoprene (IP), is particularly attractive as a biomaterial because of its elastomeric mechanical properties, biocompatibility, impermeability and high damping characteristics. IIR is typically vulcanized through chemical-based crosslinking mechanisms. However, these methods are not acceptable for biological applications. This thesis focuses on the synthesis of IIR-polyester graft copolymers by grafting biodegradable and biocompatible polyesters including poly(caprolactone) (PCL) and poly(d,l-lactide) (PDLLA) to …