Aerosol recovery from large-volume reservoir delivery systems is highly dependent on the static properties of the reservoir
In this study, the role of electrostatic fields on aerosol recovery from a system with a large collapsible reservoir (30 L) was investigated. In addition, the efficacy of the reservoir method for bronchial challenge procedures was assessed in vivo. Aerosol recovery was determined by measuring the fraction of aerosol (0.05% 99mTc-tagged human albumin solution) retrieved from the reservoir. Before aerosol recovery experiments, electrostatic fields in the reservoir were measured. Aerosol recovery varied significantly with wall thickness of the reservoir and presence of an antistatic coating (range 6.0-70.3%). A close inverse relationship was found between the mean electrostatic field in the reservoir and aerosol recovery. The nebulized provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second in asthmatics was found to be approximately half that of a standard method when compared with the reservoir system (mean ratio 2.24 (95% confidence interval, 1.60-3.12)). Recovery from an aerosol delivery system with a relatively large collapsible aerosol reservoir was highly dependent on the electrostatic field in the reservoir. In these systems the use of electrostatic field dissipative material for the reservoir is therefore recommended.
Physical properties of aerosols produced by several jet- and ultrasonic nebulizers.
In order to estimate the administered dose of inhaled drugs from aqueous aerosols, we have examined the output characteristics of eleven jet- and nine ultrasonic nebulizers. Under various operating conditions we measured driving pressure, airflow, solution- and solute output of the nebulizers, particle concentration and size distribution in the aerosol. The particle size distributions were determined of the dry particles from evaporated droplets of aerosolized 9 mg X ml-1 NaCl solutions by using a mobility aerosols spectrometer. These physical properties of the aerosols were found to vary considerably between nebulizers (even among specimens of the same type). Solution output per litre of air from the ultrasonic devices was 2 to 10 times larger than that from the jets, being dependent on electric power and driving pressure respectively. The jet nebulizers showed the largest particle concentration per litre of air. The volume median aerodynamic diameter of the droplets generated by the jet nebulizers was about 1.5-4 microns. With the exception of the Siemens TV 6000 and the Bosch Halomed, this diameter ranged between 3 and 7 microns among the ultrasonic nebulizers, being dependent on the frequency of the ultrasonic vibrations. The output characteristics appeared also to be affected by extension tubes, air vents, solute concentration and airflow. Solute output varied nonproportionally with solution output, which confirms the comparative merit of output measurements by weighing. The results of the present study can be used to estimate the administered dose of therapeutic or provocative agents by nebulizer equipment. Actual drug output can only be quantified by careful calibration of each separate set-up.
Suitability and water quality criteria of an open drainage municipal sewage water at Coimbatore, used for irrigation.
Sanganur canal is the major open drainage system which has intricate linkage with storm water supply, domestic sewage and industrial effluent disposal. Water samples from various stations were collected and analysed for physicochemical parameters to assess the water quality of the Sanganur canal system. The study revealed that physicochemical parameters like pH, EC, TDS, DO, BOD, COD exceeded the permissible limit, clearly indicating the need of proper treatment of waste water before discharge into the Noyyal river.