Drug delivery via skin is a non-invasive, patient compliant, and effective method for circulatory or skin-targeted therapeutic treatment. Based on its mechanism of action, a topical system employing cromolyn sodium (CS) poses as a cheaper, safer alternative to current treatments for atopic dermatitis, an allergic skin disease. Clinical studies have successfully treated atopic dermatitis with CS emulsions; however, semisolid CS gels have not been investigated and no commercial formula is available to date. Additionally, clinical doses of CS do not passively permeate skin, although different chemical enhancers can be incorporated into formulation to enhance cutaneous drug absorption. This study aimed to investigate salcaprozate sodium (SNAC) as a chemical enhancer for optimized drug delivery to the dermis for potential remedial effects of CS gels. Gels were prepared weight-to-weight by combining 4% CS, 1% hydroxypropyl cellulose as gelling agent, and respective amounts of propylene glycol as base. For SNAC gels, contents included 2.5%, 4.5%, and 9% SNAC, and amount of propylene glycol was adjusted accordingly. CS gel (4%) containing no SNAC was used as a control. After overnight shaking, gels were sonicated for 30 min to use in in vitro permeation studies. Porcine ear skin was mounted on Franz diffusion cells maintained at 37°C, and permeation studies were performed over 24 h for each formulated gel to determine their effect on CS permeation across skin. Donor compartment contained 100 μL gel while the receptor held phosphate buffered saline (PBS). At predetermined timepoints, 300 μL of receptor solution was sampled, replaced with fresh PBS, and analyzed using HPLC with CS detection at 236 nm. Following 24 h, remaining gel was removed, and skin surface was cleaned. Skin layers were manually separated, minced, and left to shake for 4 h to extract permeated drug using methanol. These samples were vacuum dried overnight and reconstituted with PBS to be analyzed using HPLC. Efficiency of skin extraction methods was evaluated by assessing amount of drug recovered from skin compared to amount of drug absorbed where results were plotted, and subsequent equations were used to correct skin data. Student’s T test with Welch’s correction was applied to confirm statistical significance between gels. Passive delivery of the 4% CS control gel to the dermis was 0 μg/cm2. The SNAC containing gels demonstrated significantly improved drug delivery to the dermis when compared to control for 2.5% (36.26 ± 13.05, p=0.05), 4.5% (11.64 ± 1.45, p=0.001), and 9% (35.87 ± 2.23, p=0.004) SNAC groups. No significant differences were observed between any SNAC gel group and the control gel regarding drug delivered to the epidermis or receptor over 24 h. This study observed the greatest delivery of CS to the dermis with the 2.5% SNAC gel, posing as a promising option for a commercially available topical CS gel for the skin-targeted treatment of atopic dermatitis.

No description available.

No description available.

No description available.

No description available.

<p> The work of this study is divided into two parts. Part I reports on the development of a dedicated minicomputer, data acquisition, and reduction system for GPC. The hardware, software, and operating performance of the system is discussed in some detail.</p> <p> Part II, reports on an experimental study design to determine whether axial dispersion corrections are universal in the sense of being independent of polymer composition. Results for poly(vinyl-chloride), polystyrene, polybutadiene, and poly(methy-methacrylate) are discussed.</p> / Thesis / Master of Engineering (MEngr)

No description available.

High energy consumption is a crucial challenge in gas separation processes. With current energy intensive separation methods, there is a real need for more energy-efficient alternative technologies. Membrane technology demonstrates potential uses in industrial separation processes due to its potential energy efficiency, environmental friendliness, and small footprint. The continuous developments in material science contributed directly in enhancing the membrane performance through several engineering modifications such as thermal annealing, which presented visible improvements in gas permeation properties. The objective of this project was to investigate the thermal annealing of three fluorinated polymers (PAE1, PAE2, and TFMPD), aiming for favorable changes in gas permeation properties. In particular, each polymer was annealed for 3 h at various temperature values, targeting the intermediate stage, which is the zone where degradation started but a pure carbon structure stage was not formed yet. Overall, the thermal annealing study revealed that TFMPD had highest pure-gas separation performance among other polymers, in which the Robeson plots displayed that treated sample at 500 ºC surpassed the 2015 H2/CH4 upper bound, whereas the treated sample at 550 ºC surpassed 2019 upper bound of both CO2/CH4 and CO2/N2. Therefore, TFMPD can be a potential candidate polymer for membrane-based gas separation, especially for CO2 and H2 applications. This performance could be attributed to the internal structural changes in the polymer that occurred during thermal annealing. Hence, several characterization techniques were performed to detect these changes. For instance, it was realized that all polymers started crosslinking upon the thermal treatment at 350 ºC. Moreover, FTIR analysis indicated the release of several functional groups from treated polymers at high temperature values. Raman spectroscopy also confirmed that the observed substantial enhancement in gas permeation of annealed TFMPD at 550 ºC was due an early-stage carbon structure formation. Furthermore, several recommendations are proposed to continue the work in this project, which could lead to potential success of the thermally annealed polymers tested in this study in membrane-based gas separations applications.

The purpose of this investigation was to propose a method to determine the composition distribution, on one hand, and the molecular weight distribution, on the other hand, for block copolymers. The technique selected to determine this kind of information was Gel Permeation Chromatography, because, since its introduction in 1964, it has become the most powerful tool for the rapid characterization of homopolymers. The proposed method is introduced by considering a dual-approach: composition distribution (calibration of detectors with composition) and molecular weight distribution (calibration of columns with composition). The absence of heterointeractions in block copolymers led to a behavior which depends solely on the elution behavior of the corresponding homopolymers. Finally, it is concluded that all this meaningful information about block copolymers can be perfectly obtained when adequate raw Gel Permeation Chromatography data handling, taking into account composition, is done. / M.S.

In this work the synthesis, characterization, and gas transport properties of hydrogen selective silica membranes were studied along with the catalytic reforming of CH₄ with CO₂ (CH₄ + CO z 2 CO + 2 H₂) in a hydrogen separation membrane reactor. The silica membranes were prepared by chemical vapor deposition (CVD) of a thin SiO₂ layer on porous supports (Vycor glass and alumina) using thermal decomposition of tetraethylorthosilicate (TEOS) in an inert atmosphere. These membranes displayed high hydrogen permeances (10⁻⁸ - 10⁷ mol m⁻² s⁻¹ Pa⁻¹) and excellent H₂ selectivities (above 99.9 %) over other gases (CH₄, CO, and CO₂). The membranes were characterized using Scanning Electron Microscopy and Atomic Force Microscopy, and the mechanism of gas transport was studied applying existing theories with a newly developed treatment. The catalytic reforming of CH₄ with CO₂ was carried out in a membrane reactor installed with a hydrogen separation ceramic membrane. The reaction was conducted at various pressures (1 - 20 atm) and temperatures (873 K and 923 K) at non-equilibrium conditions, and the results were compared with those obtained in a packed bed reactor in order to evaluate performance of the membrane reactor for the reaction. It was found that concurrent and selective removal of hydrogen from the reaction in the membrane reactor resulted in considerable enhancements in the yields of the reaction products, H₂ and CO. The enhancements in the product yields in the membrane reactor increased with pressure showing a maximum at 5 atm, and then decreased at higher pressures. This was due to a trade-off between a thermodynamic quantity (hydrogen production by the reaction) and transport property (hydrogen separation through the membrane). It was also found that the reverse water-gas shift (RWGS) reaction occurred simultaneously with the reforming reaction giving the detrimental effect on the reaction system by reducing the amount of hydrogen production in favor of water. This was particularly significant at high pressures. / Ph. D.