Objective: Prophylactic strategies against invasive pulmonary aspergillosis are often limited by drug interactions and toxicities. Targeted airway delivery of antifungals to the lungs may avoid these pitfalls. We evaluated the effectiveness of an aerosolized nanostructured formulation of itraconazole produced by spray freezing into liquid (SFL) as prophylaxis against invasive pulmonary aspergillosis caused by A. fumigatus. Methods: Immunocompromised Balb/C mice received either itraconazole by oral gavage (Sporanox Oral Liquid [SOL] 30 mg/kg TID) or by aerosolization (SFL 30 mg/kg via 20 min aerosolizations, or control, BID). Dosing began 2 days prior to pulmonary inoculation with A. fumigatus and continued for 7 days post-inoculation. Changes in lung histopathology were also assessed. In the survival arm, mice were monitored over a 5 day period following discontinuation of therapy and survival was assessed by Kaplan-Meier analysis. Results: SFL survival (35%) was greater compared to control (10%; p = 0.03) and SOL (10%; p = 0.02). Histopathology demonstrated severe invasive disease involving vessels and small airways in control and SOL animals. SFL animals demonstrated colonization with some invasion predominately of large airways. Conclusions: Prophylactic aerosolization of nanostructured SFL significantly improved survival and limited invasive disease of small airways due to A. fumigatus. (c) 2007 The British Infection Society. Published by Elsevier Ltd. All rights reserved.
CO2 promotes penetration and removal of aqueous surfactant cleaning solutions in methylsilsesquioxane (MSQ) low dielectric constant (k) films with 3 nm hydrophobic open pores. The films were characterized by mercury probe dielectric constant (k value) measurements and FTIR spectroscopy. Penetration of a solution of 2 wt.% polyoxyethylene 2,6,8-trimethyl-4-nonyl ether, 5b-C12E8, in H2O at ambient pressure increased the k value of etched and N-2/H-2 ashed JSR 5109 pMSQ from 2.5 to 7.6, indicating 68% of the total pore volume was filled with the solution. This level of penetration was corroborated by the OH peak at 3150-3560 cm(-1) and the CH3 peak (surfactant) at 2800-3000 cm(-1). Rapid removal of the surfactant solution was achieved by rinsing and drying with 10 mL/min supercritical carbon dioxide (scCO(2)) at 45 degrees C and 10 MPa for 2 min. Both water and surfactant are dissolved and emulsified into CO2. Nearly complete removal of the surfactant and water was observed in the k value, which dropped to 2.5, and in the OH and CH3 peak areas. In addition, the cleaning and drying steps may be integrated with silylation in CO2 to remove silanol groups and to add carbon to further reduce the k value. After rinsing and drying with CO2, silylation with 1 wt.% hexamethyldisilazane (HMDS) in CO2 at 45 degrees C and 10 MPa followed by annealing at 380 degrees C for 60 min led to a k value of 2.3, near the original value of 2.15. The ability of CO2 to lower the magnitude of the capillary pressure well below the total pressure facilitates removal of the surfactant solution during rinsing and drying. These results suggest that aqueous surfactant solutions, mixed with CO2, may offer significant advantages for cleaning and drying patterned low-k dielectric insulators, particularly as the feature size shrinks below 50nm and capillary forces become significant. (c) 2007 Elsevier B.V All rights reserved.
A comparison study has been conducted on the formation of catalyst nanoparticles on a high surface tension metal and low surface tension oxide for carbon nanotube(CNT)growth via catalytic chemical vapor deposition (CCVD). Silicon dioxide (SiO2) and tantalum have been deposited as supporting layers before deposition of a thin layer of iron catalyst. Ironnanoparticles were formed after thermal annealing. It was found that densities, size distributions, and morphologies of ironnanoparticles were distinctly different on the two supporting layers. In particular, ironnanoparticles revealed a Volmer-Weber growth mode on SiO2 and a Stranski-Krastanov mode on tantalum. CCVD growth of CNTs was conducted on iron∕tantalum and iron∕SiO2. CNTgrowth on SiO2 exhibited a tip growth mode with a slow growth rate of less than 100nm/min. In contrast, the growth on tantalum followed a base growth mode with a fast growth rate exceeding 1μm/min. For comparison, plasma enhanced CVD was also employed for CNTgrowth on SiO2 and showed a base growth mode with a growth rate greater than 2μm/min. The enhanced CNTgrowth rate on tantalum was attributed to the morphologies of ironnanoparticles in combination with the presence of an iron wetting layer. The CNTgrowth mode was affected by the adhesion between the catalyst and support as well as CVD process.
We examine the contact angle of water droplets on polystyrene (PS) thin films of varying thicknesses supported by silicon wafers under both air and pressurized carbon dioxide (CO2) environments. At 23 degrees C, the contact angle is found to increase upon increasing CO2 pressure in the vapor regime and then levels off in the liquid CO2 regime. A macroscopic model based on Young’s equation and the geometric-mean method for interfacial tensions, and long-range van der Waals interactions, correctly predicts the trends and the magnitude of the contact angle dependence on pressure, although deviations occur at high CO2 activities. The contact angle was also found to depend on film thickness, h, when h was comparable to or smaller than 50 nm. Specifically, the contact angle decreases with decreasing PS film thickness. This behavior could be accounted for with the use of a model that incorporates the effects of film thickness, CO2 pressure, and the long-range van der Waals potential.