Engineering Commons^™

A Detailed Parameter Study Into The Dermal Absorption Of Chemical Warfare Agents And The Effects Of Pharmacokinetics, Koko Lear

Theses

Chemical warfare agents (CWAs) are substances of varying toxicity profiles. These chemicals exhibit complex dynamics and pose a serious health risk when released into the environment. A mathematical model based on Fick’s second law of diffusion was developed to comprehend how these compounds were absorbed into the skin. The analysis applied to both small and large doses and, successfully, predicted experimental results. This work also includes the effects of CWA physicochemical properties on evaporation and dermal absorption through the stratum corneum. A sensitivity analysis was conducted to assess the impacts of small variations in the initial dose, environmental conditions, and …

Modeling Mass Transfer And Chemical Reaction In Industrial Nitrocellulose Manufacturing Processes, Francis Patrick Sullivan

Dissertations

A series of models are proposed to describe the production of military grade nitrocellulose from dense cellulose materials in mixtures of nitric acid, sulfuric acid, and water. This effort is conducted to provide a predictive capability for analyzing the rate and extent of reaction achieved under a range of reaction conditions used in the industrial nitrocellulose manufacturing process for sheeted cellulose materials. Because this capability does not presently exist, nitrocellulose producers have historically relied on a very narrow range of cellulose raw materials and resorted to trial and error methods to develop processing conditions for new materials. This tool enables …

New Screening Methodology For Selection Of Polymeric Materials For Transdermal Drug Delivery Devices, Roberto P. Falcone

Dissertations

As medical advances extend the human lifespan, the level of chronic illnesses will increase and thus straining the needs of the health care system that, as a result, governments will need to balance expenses without upsetting national budgets.

Therefore, the selection of a precise and affordable drug delivery technology is seen as the most practical solution for governments, health care professionals, and consumers.

Transdermal drug delivery patches (TDDP) are one of the best economical technologies that are favored by pharmaceutical companies and physicians alike because it offers fewer complications when compared to other delivery technologies. TDDP provides increased efficiency, safety …

Surface And Bulk Passivation Of Multicrystalline Silicon Solar Cells By Silicon Nitride (H) Layer : Modeling And Experiments, Chuan Li

Dissertations

The objective of this dissertation is to study passivation effects and mechanisms in Si solar cells, specifically, the surface and bulk passivation by hydrogen-rich PECVD silicon nitride (SiN :H) antireflection layer on multicrystalline silicon (me-Si) solar cells.

The passivation of silicon surface can be achieved in two ways: by field-effect passivation and/or by neutralization of interface states. In other words, the deposition should result in a high value of fixed charge, Qf and /or a low value of interface state density, D1. The surface recombination velocity can be described by Shockley-Read-Hall (SRH) statistics.

Current SRH formalisms have failed to explain …

Boron And Phosphorous Implantation Into (100) Germanium : Modeling And Investigation Of Dopant Annealing Behavior, Yong Seok Suh

Dissertations

Germanium is increasingly being considered at this time for future silicon compatible optoelectronic and complementary metal oxide semiconductor (CMOS) device application. Germanium implantation will be a critical process for future device fabrication. However, critical properties like Pearson parameters and dopant activation temperatures are not well established. In this study, boron and phosphorus were implanted into (100) germanium with energies ranging from 20 to 320 keV and doses of 5 x 10¹³ to 5 x 10¹⁶ cm^-2. The behavior of the boron and phosphorus before and after annealing for 3 hours at 400, 600 or 800°C in …

Simulation Of Particle Size Distribution In Continuous Emulsion Polymerization Through A Modified Population Balance Approach, Ying-Yuh Lu

Theses

A detailed mathematical model for particle size distribution in continuous emulsion polymerization of styrene and vinyl acetate is proposed on the basis of the population balance in the presence of several kinetic and mass transfer processes. This study is limited to the Smith-Ewart case II, which assumes instantaneous free radical termination within polymer particles. Radical desorption mechanism from polymer particles is included in the model and the desorption rate is formulated from the diffusion theory which suggests that the rate coefficient should be inversely proportional to the surface area of polymer particles.

Correlation And Prediction Of Diffussion Coefficients In Binary Gas Systems, Raymond Gerald Bailey

Theses

A correlation was developed for estimating binary gas diffusion coefficients by the reference substance method, in this case using the viscosity of air and subsequently its corresponding temperature. The derivation was made by the linear least square analysis of 65 different binary systems comprising 161 separate data points at temperatures ranging from 193°K. to 1200°K. At any given temperature only the critical molal volume and the molecular weights of the two gases of interest are required to calculate the diffusion coefficient. The correlation based on the viscosity of air had an average error of 7.67%. The correlation using temperature had …

Application Of Radioactive Tracers In The Study Of Diffusional Phenomena, Rodolfo Cilento

Theses

The study of mass transfer of a solute through a solvent can be greatly facilitated by the use of radioactive tracers.

This experiment was developed to demonstrate that by using radioactive tracers very small quantities of matter that would be very difficult to test chemically, can not only be tested but easily followed without disturbing the apparatus in which the diffusion is taking place.

Oleic Acid tagged with radioactive iodine (I¹³¹) was diffused through hexane at constant temperature in a glass column, one inch in diameter and thirty-six inches long.

The diffusion of Oleic Acid was followed by …

Diffusion Of Single And Multicomponent Solutes From Capillaries, Oleh S. Sklepkowycz

Theses

The purpose of this investigation was to determine the diffusion coefficients of several single and multi-component solutes, and to establish the relations between the diffusivity, the solute composition) and the diffusion rate. Such information pertinent to the extraction and leaching operations, can not be found in literature.

The procedure developed by Piret, Wbel, and Armstrong (25), involving observation of the extraction rate of two-phase mixtures from straight capillaries, was adopted and verified on a known sodium chloride-water system.

In the course of the experimental work diffusion coefficients more determined for ursolic acid, palmitic acid, and tripalmitin in methyl isobutyl ketone. …

Interphase Gas-Liquid Mass Transfer Study In A Horizontal Channel, Bruce R. Marx

Theses

The rate of transfer of hydrogen sulfide and of carbon dioxide from an atmosphere of the gas saturated with water to a flowing stream of water in a horizontal channel was investigated over a range of water flow velocities and absolute pressures.

Mathematical models describing the system in terms of the penetration and boundary layer theories were inadequate when used to calculate the diffusivity of each gas in water at various conditions. The results of the hydrogen sulfide-water system study shows a relationship between the diffusivity, the interfacial concentration and the liquid flow rate. The calculated diffusivity of the carbon …

Mass Transfer Into Cylindrical Liquid Films Measurement Of Liquid Diffusivities, Ronald Francis Lovenguth

Theses

This thesis was undertaken to augment and validate the previous work of Ratcliff and Reid⁽⁷⁾ in the area of diffusion of immiscible liquids. Their novel approach to this particular problem of liquid diffusion led the author to consider an experimental technique that has been used in gas-liquid studies. A short vetted-wall column was used to determine the rate of mass transfer of benzene and toluene into thin cylindrical films of water. A general analytical solution for the rate of mass transfer has been derived and is given below. This solution was checked using the system benzene-water.

G=3.63(Π(ρ_ω-ρ …

A Study In Diffusion, Nicholas James Driscoll

Theses

The object of this thesis was to build an experimental apparatus and to study the diffusion of crystal violet in ethanol-water mixtures and diacetone alcohol-water mixtures. In order to validate experimental technique and to check the work of Mouquin Cathcart(1) who postulated compouhd formation in ethanol-water based on diffusion studies, experiments were conducted on the ethanol-water system in the area where compound formation was predicted.

In order to check the proposal of Konrad(2), based on studies of the heats of mixing that compound formation occurs between diacetone alcohol and water, studies were made on the diffusion of crystal violet in …

Effect Of Concentration On The Mass Transfer Coefficient In The Liquid Film, Marvin Baker Schaffer, Philip Major Pomerantz

Theses

The effect of liquid concentration on the resistance to mass transfer across the liquid film is studied for an acetone-methyl isobutyl ketone-air system in a packed tower. The liquid film resistance is computed by measuring the overall resistance for various concentrations and subtracting the gas film resistance. The gas film resistance is determined at the same liquid and gas rates by measurements on the pure components.

In the theory developed to handle the calculations, it is assumed that the interface temperatures are the wet-bulb temperatures based on a dynamic equilibrium. This supposition is supported experimentally at a liquid rate of …