Standing cloud

The active inhaler made by Nektar Therapeutics (formerly Inhale Therapeutic Systems, United States), called Pulmonary Delivery System (PDS), mechanically compresses a fixed volume of air required for delivery and dispersion of a premetered dry-powder unit dose by a spring-loaded pump (Fig. 8.10). Generation of the respirable aerosol cloud thus is independent of the inspiration effort exerted by the patient. The aerosol is generated in a transparent holding chamber that acts as a spacer from which the patient inhales the standing cloud of particles (Patton 1997). The PDS device is actually close to market for inhaled delivery of insulin under the trade name Exubera. 

Dose reproducibility Several human studies comparing aerosol insulin administration to subcutaneously administered insulin showed that the variability in glucose response from a liquid nebulizer that utilized the standing cloud concept was equivalent or better than that seen with insulin injection. Inhale Therapeutics Systems, Inc. has adopted this standing cloud concept for its dry powder inhaler to achieve reproducibility of delivery of macromolecules to the systemic circulation that is equivalent to subcutaneous injections. 

Figure 1 Sketch illustrating principles of the standing cloud technique. Aerosol particles produced hy the nebulizer are captured by the output filter, direct analysis of drug or a marker of the drug such as a radiolabel provides a quantitative estimate of nebulizer function. (Modified from Ref. 7.)...

Figure 2 Relationship between aerosol measured by the standing cloud technique and weight change for a number of commercial nebulizers. There is a correlation between the two techniques (r = 0.924, p< 0.0001) slope of the fine (0.619) is not equal to identity. (From Ref. 7.)...

Figure 18 Aerosol distributions of saline particles produced by Fisoneb. Open circles, standing cloud aerosol-filled circles, saline aerosol following ventilation of nebulizer with Harvard pump. (From Ref. 10.)...

The primary objective of a spacer is to minimize the need for coordination between actuation of the pMDI and inhalation. In addition, the spacer should ensure that the aerosol particles trail the inspiratory flow of the patient, reduce the proportion of the dose contained in large particles, and increase the proportion contained in small particles (12). The need for coordination between actuation and inhalation is reduced by presenting the aerosol to the patient as a standing cloud of particles, which decreases oropharyngeal deposition. Oropharyngeal deposition with the actuator alone ranges from 30 to 70%, compared with 5-10% with spacer devices (13,14). 

A few years later carbon dioxide was injected into an underground tank containing Jet fuel as a tryout of a fire-fighting system. The tank blew up, killing 18 people who were standing on top of the tank. In this case the discharge may have occurred from the cloud of carbon dioxide particles. 

On January 22, 1972, an overspeeding tank car containing iiquefied propyiene coilided with a standing hopper car at a shunting yard in East St. Louis, Illinois. As a result, the tank of the tank car was punctured, and propylene gas was released. A large vapor cloud was formed, which then ignited and exploded. More than 230 people were injured. 

The coupler of the hopper car punctured the head of the first tank car. Liquefied propylene was spilled, and propylene vapor was observed as a white cloud spreading at ground level. The hopper car was set into motion by the impact from the three-car unit, and the four cars rolled down the track together until they struck cars standing at 700 m (2300 ft) from the hump end of the track. This impact resulted in an enlargement of the tear in the leading tank car. 

The acid, without drying, is suspended in about 200 cc. of distilled water and with vigorous stirring, cautiously (Note 3) treated with 25 per cent sodium hydroxide solution until dissolved and the solution reacts neutral to litmus. The solution is then filtered through folded filter paper which should be free from soluble calcium salts, otherwise the filtrate will remain clouded by a suspension of the calcium salt. The clear, faintly yellow or colorless filtrate is then vigorously stirred and treated with 1.5 volumes of 95 per cent alcohol. Crystallization is induced by rubbing with a rod and then an additional volume of alcohol is added. The mixture should be allowed to cool to about 200 and stand for at least two hours to complete the precipitation of the salt, which is then filtered by suction and washed thoroughly with 85 per cent alcohol. The salt is then air-dried. The yield is 73-77 g. (38-40 per cent of the theoretical amount). 

The wick of the sample paper can either be ignited before the stopper is placed in the flask neck, or better still ignited by remote electrical control, or by an infrared lamp. In any case combustion is rapid and usually complete within 5-10 seconds. After standing for a few minutes until any combustion cloud has disappeared, the flask is shaken for 2-3 minutes to ensure that complete absorption has taken place. The solution can then be treated by a method appropriate to the element being determined. 

The first two types are of long-standing commercial availability. They are applied using magnesium chloride as catalyst and are crosslinked by addition of ammonia. An important factor is that magnesium chloride induces a cloud point at about 50 °C, leading to the... 

Throughout the book I have tried to constrain the wonders of imagination inspired by the subject by using simple calculations. Can all of the water on the Earth have been delivered by comets if so, how many comets How do I use molecular spectroscopy to work out what is happening in a giant molecular cloud Calculations form part of the big hard-sell for astrochemistry and they provide a powerful control against myth. I have aimed the book at second-year undergraduates who have had some exposure to quantum mechanics, kinetics, thermodynamics and mathematics but the book could easily be adapted as an introduction to all of these areas for a minor course in chemistry to stand alone. 

At the time it was diagnosed as motion sickness, but in fact it was not motion sickness. He couldn t stand the smell of gas. Our cars and buses bum diesel, and no one cares about the amount of emissions. There are black clouds of exhaust fumes everywhere. 

Disregarding for a moment the bright and dark bands that decorate the spectrum of a heavenly body at specific wavelengths, the overall hue of that spectrum can tell us the surface temperature of the object. A blue star is thus hotter than a yellow one, and a yellow star is hotter than a red one. The Sun is hotter at the surface than the red star Antares, which in turn stands as a torrid desert before the brown dwarfs or interstellar clouds. The stars go red with cold. 

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