A slip correction factor is used to correct Stokes' law for the fact that the no-slip boundary condition is violated for small aerosol particles moving with respect to the gaseous medium. The Knudsen-Weber form of the slip correction is given by C(Kn) In this study an improved version of the Millikan apparatus was designed, built, and used to measure the slip correction factors for 90 solid, spherical particles in air. Measurements were made on 11 polystyrene latexdivinylbenzene particles, 25 polyvinyltoluene particles, and 54 polystyrene latex particles, spanning a Knudsen number range from 0.03 to 7.2. The fitted nonlinear least squares values of a, $, and y are 1.142 (+0.0024 SE), 0.558 (+ 0.0024 SE), and 0.999 (k 0.0212 SE), respectively, for the assumed mean free path of 0.0673 pm for air at sea level and 23°C with viscosity of 183.245 micropoise. This value of a agrees very closely with Millikan's result (adjusted to the same mean free path).
Quantitative anatomical descriptions (morphometry) of the tracheobronchial airways are of importance in many applications including the preparation of successful mathematical models describing airflow patterns and deposition patterns of airborne particles in the lung. Morphometric data are also useful in studies of comparative anatomy and in describing normal and diseased states of an organ. The collection of such data is aided by the use of idealized models of airway branches of the tracheobronchial airways. Morphometric measurements from the lungs of several mammalian species are presented using a model that consists of three connected tubular segments. The morphometric model uniquely defines an identification number for each branch segment, a branching angle, an airway segment length and diameter, an inclination of a segment to gravity and the degree of alveolarization of each segment. Designed to be compatible with computerized data handling, the model is unambiguous and realistic, but flexible so that anomalous anatomical structures can be classified and noted. Morphometric data describing the variation of structure with depth in the tracheobronchial airways are presented in the form of graphical representations of anatomical measurements on replica casts of the human, dog, rat and hamster airways. These distributions describe the anatomical character of the tracheobronchial airways concisely, quantitatively, and characteristically for each species.
Silicone rubber casts were prepared of the nasal, pharyngeal and laryngeal regions of two rats, a rhesus monkey, and three beagle dogs and one for each species selected for detailed measurements. Cross-sections of the casts were made and the area and perimeter of each section measured using an image analyzing computer. Considerable anatomical differences were found between the species. Some of the differences, such as the sharp bend in the nasopharynx of the monkey, could be related to normal posture. One of the main differences was the greater complexity of the turbinate region of the dog as compared to the corresponding area of the monkey.
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