Vapor delivery systems

Another delivery system is shown in Fig. 5.4, where a mass-flow controller injects a carrier gas into a heated bubbler. The carrier gas becomes saturated with the reactant vapor, which is then carried into the deposition chamber through a pressure controller and flowmeter.C]... 

A number of new approaches to the way in which precursors are delivered to a substrate have been developed in which the precursor is dispersed into the gas phase without having to be volatile. These new systems each have their own advantages for a particular precursor depending on its physical state. Most of the delivery systems in use can be classified as one of the following a liquid injection system (LIS), where a precursor is vaporized directly from a neat liquid or solution containing the precursors a solid delivery system (SDS), where the precursor is vaporized... 

Similar to chemical vapor deposition, reactants or precursors for chemical vapor synthesis are volatile metal-organics, carbonyls, hydrides, chlorides, etc. delivered to the hot-wall reactor as a vapor. A typical laboratory reactor consists of a precursor delivery system, a reaction zone, a particle collector, and a pumping system. Modification of the precursor delivery system and the reaction zone allows synthesis of pure oxide, doped oxide, or multi-component nanoparticles. For example, copper nanoparticles can be prepared from copper acetylacetone complexes [70], while europium doped yttiria can be obtained from their organometallic precursors [71]. 

O Brien P, Pickett NL, et al (2002) Developments in CVD delivery systems, A chemist s perspective on the chemical and physical interactions between precursors. Chemical Vapor Deposition 8(6), 237-249... 

The chemical structures of the currently available inhaled anesthetics are shown in Figure 25-2. The most commonly used inhaled anesthetics are isoflurane, desflurane, and sevoflurane. These compounds are volatile liquids that are aerosolized in specialized vaporizer delivery systems. Nitrous oxide, a gas at ambient temperature and pressure, continues to be an important adjuvant to the volatile agents. However, concerns about environmental pollution and its ability to increase the incidence of postoperative nausea and vomiting (PONV) have resulted in a significant decrease in its use. 

Have a sitter (this is especially important if you are new to Salvia, taking a high dose or using an efficient delivery system such as vaporization. 

Gas-separation manager includes both vapor recovery and gas-separation systems. Vapor recovery handles the recovery of valuable condensable components from a gas stream or the removal of undesired components since they are corrosive, toxic, polymerizable, have a bad odor, etc. Gas separation deals with the recovery of recycled gaseous reactants, as well as with the delivery of purified products and byproducts. Douglas [6] recommends the following heuristics for placing the vapor-recovery system ... 

The acaricldal activity of propargite occurs primarily through vapor action, while the phytotoxic effects seem to arise only from direct contact with the plant leaf or fruiting body. Conceptually, therefore, a delivery system vdiich could prevent contact with the plant, yet allow the acaricldal vapor to escape, would prevent phytotoxicity and allow use on sensitive crops. 

Fine water spray systems may be potentially superior to CO2 applications and may replace halon environments such as telephone central offices and computer rooms. In the fine spray delivery system, water is delivered at relatively high pressure (above 100 psi [0.689 MPa]) or by air atomization to generate droplets significantly smaller than those generated by sprinklers. Water flow from a fine spray nozzle potentimly extinguishes the fire faster than a sprinkler because the droplets are smaller and vaporize more quickly. Preliminary information indicates that the smaller the droplet size, the lower the water flow requirements and the less chance of water damage. 

To date, Monteiro-Riviere and co-workers [60] have published the only studies using electron microscopy to examine the mechanism of iontophoretic transport. They applied mercuric chloride (7.4%) in vivo in pigs for 1 hr (current density 200 p,A/cm ) and subsequently exposed the biopsies to ammonium sulfide vapor to precipitate and localize the mercury, similar to earlier passive transport studies [28]. The micrographs revealed that mercuric chloride traverses intracellularly through the first few layers and intercellularly through the remainder of the stratum comeum. The authors concluded that the intercellular pathway is the predominant route for passive and iontophoretic drug delivery systems. However, it is difficult to eliminate follicular transport as a possible pathway, since only small areas can be examined at a time ( 1 mm ) and the low density of hair follicles (11/cm ) makes it difficult to study them with the electron microscope. 

Vahlas and coworkers recently tested a new delivery system based on sublimation in a fluidized bed, to improve mass and heat transport. A mixture of solid Al(acac)3 (minor component) and inert alumina or silica particles was fluidized with a combination of water vapor and oxygen at 150 °C, by which amorphons AI2O3 films were obtained on Ti6242 alloy wafers immersed in the bed. Pauleau and Dnlac compared the kinetics of vaporization of Al(acac)3, Al(tfac)3 and Al(hfac)3 by isothermal TGA. The satnration vapor pressure of Al(hfac)3 is 10-fold and 100-fold higher than those of Al(tfac)3 and Al(acac)3, respectively. 

Vapor pressure-activated drug delivery systems... 

Vapor Pressure-Activated Drug Delivery Systems... 

Fig. 21 Cross-sectional view of a unit of Infusaid system, a vapor pressure-activated drug-delivery system, and daily heparin dose (mean S.E.) delivered to 25 dogs for 6 months and to 7 dogs for 12 months. (Adapted from Ref. " l)...

The distillation eliminates virtually all significant contaminants. The vapor phase will not transport colloidal rust from water-contaminated steel cylinders. Greases and oils are not volatile at the temperature of the distillation. Small residuals of nitrogen, oxygen, and even water at the 5-10-ppm level usually do not interfere with analysis or purification. In fact, after a break-in period, the gas delivery system in our laboratory provides significantly lower background noise in SFC-MS than cylinders filled with SFC-grade CO2. 

Urine (Matusiewicz and Barnes, 1985) - NIOSH-NBS freeze dried urine is reconstituted in water. 50 nL samples are determined. Instrumentation Plasma-Therm model 5000D ICP-AES spectrometer. Instrumentation Laboratory FASTAC II pneumatic nebulizer/aerosol delivery system to deliver sample to a model IL655 furnace for graphite furnace vaporization at 2500°C. Argon plasma, 40.68 MHz, A = 231.60 nm, pyrolytically coated graphite tube with platform. Detection limit 0.9 hqIL (45 pg Ni) by peak area, 12 /peak height. Urine reference material found 1.05 mg/L (RSD 2.1%), expected 1.01 0.11 mg/L. 

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