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This article provides measurements of thermal conductivity carried out on a microelectromechanical system (MEMS) structure for the application of selective gas sensing. MEMS thermal conductivity based gas sensors work by measuring the interaction of a heated polysilicon bridge with an ambient gas and sensing temperature changes. The tiny MEMS element provides an ability to measure noble gases and is especially applicable to binary mixtures. In this work we conducted experiments on the KWJ Engineering nano-powered thermal conductivity detector (TCD) elements to investigate the sensitivity of the sensor transient responses to gas composition. Measurements are made at constant power, constant resistance, and constant energy. By introducing feedback to maintain constant sensor temperature, the relative change of gas thermal conductivity with respect to temperature can be estimated and provide information about the concentration as well as insight into the composition of the gas mixture.

Chemoembolization, using a combination of embolic and chemotherapeutic agents, appears to be an effective treatment for hepatocellular carcinoma. Although the postulated mechanism of effectiveness hinges on a prolonged drug delivery, increasing evidence suggests that embolization mixtures are not stable. The objective of this study was to investigate examples of these mixtures.Dialysis techniques have been used to examine the pharmacokinetic properties of chemoembolization mixtures that contain doxorubicin, Lipiodol (Guerbet Products, Montreal, Quebec), and the embolizing agents Avitene (Alcon Laboratories Inc., Fort Worth, Texas), Gelfoam (Upjohn, Kalamazoo, MI), and Angiostat (Regional Therapeutic Inc., Pacific Palisades, CA).Lipiodol, Gelfoam, and Avitene, when combined with doxorubicin, had only a small effect on the diffusion of the drug when compared with the diffusion curve of doxorubicin alone. Gelfoam or Avitene produced a thrombus-like consistency when added to a doxorubicin/Lipiodol combination, and an additional decrease in the doxorubicin appearance rate was observed. However, after 6 hours, doxorubicin levels for these mixtures reached control values observed in 3 hours. Angiostat without Lipiodol produced a profound concentration-dependent decrease in the diffusion of doxorubicin. After 9 hours, only 23% of the doxorubicin had been released.The strong complexing ability of the embolic agent Angiostat may enable it to be a carrier for doxorubicin and surpass other mixtures currently employed for transcatheter chemoembolization.