Electro-hydrodynamic atomization of drug solutions for inhalation purposes.
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Monodisperse aerosols show therapeutic advantages, but they are difficult to generate. A new method (electrohydrodynamic atomization) is described. A high voltage is applied to a nozzle through which a solution, containing dissolved drug, is pumped. At the nozzle tip, a liquid cone is formed and a stream of monodisperse droplets is released. The droplet diameter is governed by the density, conductivity, and the flow rate of the fluid. The droplets are charged and need to be neutralized. Therefore, a corona discharge system is used. Methylparahydroxybenzoate was used as a model drug, and additional data were generated by using beclomethasone dipropionate (BDP). At a flow rate of 1 ml/h and 0.5% methylparahydroxybenzoate, 1.58-microm particles were produced with a geometric SD of 1.18. Increasing the flow rate to 3 ml/h and the concentration to 3% resulted in 4.55-microm particles with a geometric SD of 1.29. The experiments with BDP resulted in similar particle sizes. The mass of BDP was found to range between 1.42 and 6 microg/l air. Aqueous solutions cannot be sprayed by using this setup. This method can be used to deliver antiasthma drugs to patients. (+info)
Effect of rise in simulated inspiratory flow rate and carrier particle size on powder emptying from dry powder inhalers.
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The purpose of this study was to evaluate the effect of carrier particle size and simulated inspiratory flow increase rate on emptying from dry powder inhalers (DPIs). Several flow rate ramps were created using a computer-generated voltage signal linked to an electronic proportioning valve with a fast response time. Different linear ramps were programmed to reach 30, 60, 90, and 120 L/minute over 1, 2, or 3 seconds. At the lower flow rates, 100-ms and 500-ms ramps were also investigated. Three DPIs, Spinhaler, Rotahaler, and Turbuhaler, were used to test the effect of flow rate ramp on powder emptying. To test the effect of carrier particle size, anhydrous lactose was sieved into 3 particle sizes, and 20 mg of each was introduced into #2 and #3 hard gelatin capsules for Spinhaler and Rotahaler, respectively. Emptying tests were also carried out using the on/off solenoid valve described in the United States Pharmacopeia (USP) (resulting in no ramp generation). Powder emptying increased from 9% to 46% for Rotahaler and 69% to 86% for Spinhaler from the shallowest (3 seconds to reach peak flow) to the 100-ms ramp for the 53- to 75 microm lactose size range at 30 L/minute. Similar trends were observed for larger particle size fractions at the same flow rate. However, at higher airflow rates (60, 90, and 120 L/minute), there was no significant increase in percentage of emptying within the ramps for a particular particle size range. Trends observed were similar for placebo-filled Turbuhaler and commercially available Rotacaps used with Rotahaler, with the steepest ramp demonstrating more complete emptying. Percentage of powder emptying determined by the USP solenoid valve overestimated the emitted dose compared with the ramp method at 30 L/minute for all 3 devices. Results indicate that there is a significant difference in powder emptying at 30 L/minute from the shallowest to the steepest ramp within a particular size range. Within a particular particle size range, the USP method produced more complete emptying than even the steepest ramp, especially at the lower flow rates. Thus, when the USP device is used to estimate DPI emptying at lower flow rates, the results are likely to overestimate DPI performance significantly. (+info)
Additives in plastics.
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The polymers used in plastics are generally harmless. However, they are rarely used in pure form. In almost all commercial plastics, they are "compounded" with monomeric ingredients to improve their processing and end-use performance. In order of total volume used, these monomeric additives may be classified as follows: reinforcing fibers, fillers, and coupling agents; plasticizers; colorants; stabilizers (halogen stabilizers, antioxidants, ultraviolet absorbers, and biological preservatives); processing aids (lubricants, others, and flow controls); flame retardants, peroxides; and antistats. Some information is already available, and much more is needed, on potential toxicity and safe handling of these additives during processing and manufacture of plastics products. (+info)
Electrode-reducing microorganisms that harvest energy from marine sediments.
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Energy in the form of electricity can be harvested from marine sediments by placing a graphite electrode (the anode) in the anoxic zone and connecting it to a graphite cathode in the overlying aerobic water. We report a specific enrichment of microorganisms of the family Geobacteraceae on energy-harvesting anodes, and we show that these microorganisms can conserve energy to support their growth by oxidizing organic compounds with an electrode serving as the sole electron acceptor. This finding not only provides a method for extracting energy from organic matter, but also suggests a strategy for promoting the bioremediation of organic contaminants in subsurface environments. (+info)
Prevalence of self-reported hypersensitivity to electric or magnetic fields in a population-based questionnaire survey.
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OBJECTIVES: The prevalence of medically unexplained symptoms attributed to exposure to electromagnetic fields is still largely unknown. Previous studies have investigated reported hypersensitivity to electricity in selected groups recruited from workplaces or outpatient clinics. The aim of this study was to estimate the prevalence of self-reported hypersensitivity to electric or magnetic fields in the general population and to describe characteristics of the group reporting such hypersensitivity with regard to demographics, other complaints, hypersensitivities, and traditional allergies. METHODS: A cross-sectional questionnaire survey was conducted in 1997 among 15,000 men and women between 19 and 80 years of age in Stockholm County. The response rate was 73%. RESULTS: One and a half percent of the respondents reported hypersensitivity to electric or magnetic fields. Prevalence was highest among women and in the 60- to 69-year age group. The hypersensitive group reported all symptoms, allergies, and other types of hypersensitivities included in the survey (as well as being disturbed by various factors in the home) to a significantly greater extent than the rest of the respondents. No specific symptom profile set off the hypersensitive group from the rest of the respondents. CONCLUSIONS: The results should be interpreted with caution. But they suggest that there is widespread concern among the general population about risks to health posed by electric and magnetic fields. More research is warranted to explore ill health among people reporting hypersensitivity to electric or magnetic fields. (+info)
Micro/nano encapsulation via electrified coaxial liquid jets.
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We report a method to generate steady coaxial jets of immiscible liquids with diameters in the range of micrometer/nanometer size. This compound jet is generated by the action of electro-hydrodynamic (EHD) forces with a diameter that ranges from tens of nanometers to tens of micrometers. The eventual jet breakup results in an aerosol of monodisperse compound droplets with the outer liquid surrounding or encapsulating the inner one. Following this approach, we have produced monodisperse capsules with diameters varying between 10 and 0.15 micrometers, depending on the running parameters. (+info)
The hottest thing in remediation.
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Scientists and engineers are exploring a new way to decontaminate toxic waste sites by literally turning up the heat on pollutants. The method heats the ground using electricity or steam, which mobilizes the contaminants so they can either be extracted from the ground and destroyed or actually destroyed in place. Among the targets for this method are pollutants such as creosote, solvents, and gasoline. These in situ thermal technologies also offer the benefit of reaching contaminants not previously amenable to cleanup, such as those found beneath structures and below the water table. (+info)
Membrane lipids, EGF receptors, and intracellular signals colocalize and are polarized in epithelial cells moving directionally in a physiological electric field.
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Directed cell migration is essential for tissue formation, inflammation, and wound healing. Chemotaxis plays a major role in these situations and is underpinned by asymmetric intracellular signaling. Endogenous electric fields (EFs) are common where cell movement occurs, such as in wound healing, and cells respond to electric field gradients by reorienting and migrating directionally (galvanotaxis/electrotaxis). We show that a physiological EF redistributed both EGF (epidermal growth factor) receptors and detergent-insoluble membrane lipids asymmetrically, leading to cathodal polarization and enhanced activation of the MAP kinase, ERK1/2. This induced leading-edge actin polymerization in directionally migrating mammalian epithelial cells. Inhibiting the EGF receptor-MAP kinase signaling pathway significantly decreased leading edge actin asymmetry and directional migration. We propose a model in which EF-polarized membrane lipid domains and EGF receptors cause asymmetric signaling through MAP kinase, which drives directional cell migration. A comparison is made with the mechanisms underpinning chemotaxis. (+info)