Nebulizers expression

Although hardness is a somewhat nebulous term, it can be defined in terms of the tensile modulus of elasticity. From a more practical side, it is usually characterized by a combination of three measurable parameters (1) scratch resistance (2) abrasion or mar resistance and (3) indentation under load. To measure scratch resistance or hardness, an approach is where a specimen is moved laterally under a loaded diamond point. The hardness value is expressed as the load divided by the width of the scratch. In other tests, especially in the paint industry, the surface is scratched with lead pencils of different hardnesses. The hardness of the surface is defined by the pencil hardness that first causes a visible scratch. Other tests include a sand-blast spray evaluation. 

Das A, Niven R (2001) Use of perfluorocarbon (Fluorinert) to enhance reporter gene expression following intratracheal instillation into the lungs of Balb/c mice implications for nebulized delivery of plasmids. J Pharm Sci 90 1336-1344... 

Figure 8 Analyte transport rate (expressed as equivalent volume of sample solution) as a function of sample uptake rate. A Cetac microcentric nebulizer (MCN) was used in a double-pass spray chamber. (From Ref. 422.)...

Output is often assessed by weighing the device before and after the nebulization period. Output is usually expressed as volume/unit time (mL min-1) or volume per unit airflow (mL L 1 air) although density of solutions is not always considered. Such measurements of mass output do not, however, provide information on dmg delivery rates. 

The delivery efficiency, or the nebulizer output, can be expressed in many different ways, as widely documented in the literature. Sometimes it is represented as the volume output, or solution mass output. However, it is more practical to use the drug mass emitted from the nebulizer at or near the mouthpiece to estimate the nebulizer output, because the amount of aerosolized drug mass at this point in the system is the best measure of how much drug the patient has available to inhale. 

Blow-fill technology is an aseptic process whereby the container is formed from thermoplastic granules, filled with sterile solution and sealed, all within one automatic operation. The bulk solution should have a low bioburden and is delivered to the machine through a filling system that has been previously sanitized and steam sterilized in situ. Concern has been expressed that the machine itself may generate particles. The plastic granules are composed usually of polyethylene, polypropylene or one of their copolymers and are heat extruded at 200°C into a tube. The two halves of a mould close around this tube and seal the base. The required quantity of sterile fluid is filled into the container, which is then sealed. Products packed in this way include intravenous solutions, and small volume parenteral, ophthalmic and nebulizer solutions. The... 

Figure 6 shows a photograph of three jet nebulizers. Numerous jet nebulizers are being marketed, and, indeed, some concern has been expressed about the nebulizer epidemic [140,141]. The first two nebulizers shown were selected because they are both used to deliver pentamidine to patients suffering from Pneumocystis carinii pneumonia, a secondary infection in AIDS. Of note, ultrasonic nebulizers have also been used for this purpose. Treatment of this particular disease is the most notable example of nebulizer therapy in recent years. Significantly, no other method of pentamidine aerosol generation is currently available. 

By the early 1800s, the Law of Conservation of Matter (Section 1-1) and the Law of Definite Proportions (Section 1-5) were both accepted as general descriptions of how matter behaves. John Dalton (1766-1844), an English schoolteacher, tried to explain why matter behaves in such systematic ways as those expressed here. In 1808, he published the first modern ideas about the existence and nature of atoms. Dalton s explanation summarized and expanded the nebulous concepts of early philosophers and scientists more importantly, his ideas were based on reproducible experimental restdts of measurements by many scientists. These ideas form the core of Dalton s Atomic Theory, one of the highlights in the history of scientific thought. In condensed form, Dalton s ideas may be stated as follows ... 

Both types have been investigated in detail (Olson et al., 1977 Greenfield et al., 1976, 1977 WInefordner and Latz, 1961 Schramel and Ovcar-Pavlu, 1979). In principle, using a pneumatic nebulizer, one should apply a peristaltic pump for the transport of the sample solution. Such a pump reduces the sample consumption significantly In comparison to a free sucking system (appr. 1 mUmin as against appr. 5 mU/min) and reduces the influence of viscosity and density of the sample solution to the droplet-size which will be produced by the system due to the amount of solution forced through the capillary. Therefore an important influence on the sensitivity (expressed as the slope of the calibration curve) can be nearly eliminated. 

Figure 8 Correlation between the volume median diameter of a nebulized aerosol, measured by laser diffraction, and thoracic deposition expressed as percent of total body deposition. The 95% confidence intervals represent the variability between volnnteer groups and not true intersubject variability. (From Ref. 3.)...

Figure 21 Influence of ventilator choice on aerosol output expressed as inhaled mass (%) versus time for four ventilators utilizing the Misty-Neb nebulizer. (Baxter Healthcare Corp., Valencia CA from Ref. 32.)...

If this fairly nebulous argument is correct, Eq. (15) yields the linear laws, and the conditions for their validity. The laws are understood to be correct only for times longer than those over which linear laws can only be correct if all the slowly fluctuating variables are included in the set A if a slowly varying variable is missing, fit) might have some projection on that variable, in which case the convolution form of Eq. (15) would have to be retained. Finally, an expression for L is obtained, " ... 

Detection limits are frequently reported as the concentration corresponding to three times the noise on the background during aspiration of distilled water, expressed as a standard deviation (3o). This is more appropriately referred to as the instrumental detection limit and is seldom realized in the analysis of real samples. Nevertheless, compilations of such values are useful for contrasting the behavior of different elements by ICP-AES and for comparison with other instrumental methods. A list compiled by P.W.J.M. Boumans and R. M. Barnes a number of years ago is still an accurate reflection of the state of the art, and was reproduced in a recent review [7]. With pneumatic nebulization, detection limits for 76 elements range from 0.5 ng/liter for Ca to 100 jig/liter for C and N. Metals of the first transition series are typical, with values in the range 0.1 to 1 p.g/liter. In most cases, improvements are reported with ultrasonic nebulization. 

Aerosol delivery using jet nebulizers has also demonstrated that transgene expression can be obtained in nonhuman prirtrates (59). Thus, transgene-specific protein was found to be distributed widely throughout the airway epithelium after an aerosol delivery to rhesus monkeys (59). Importantly, aerosol clinical trials... 

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