Aerodynamic behaviour

Velaga SP, Bergh S, Carlfors J. Stability and aerodynamic behaviour of glucocorticoid particles prepared by a supercritical fluids process. Eur J Pharm Sci 2004 21 501-509. 

Podczeck, F. 1998. The relationship between physical properties of lactose monohydrate and the aerodynamic behaviour of adhered drug particles. Int. J. Pharmaceut. 160 119-130. 

Gouda I. Development of a systematic theory of suspension inhalation aerosols I. A framework to study the effects of aggregation on the aerodynamic behaviour of drug particles. Int J Pharm 1985 27 99-116. 

Oggiano, L., Tro3mikov, O., Konopov, I., Alam, F., Subic, A., 2009. Aerodynamic behaviour of single sport jersey fabrics with different roughness and cover factors. Sports Eng. 12 (1), 23-28. 

The aerodynamic behaviour of aerosol particles depends on their diameter, density and shape. To compare the behavioiu of particles that have different properties with each other, the aerodynamic diameter (Da) has been introduced, which standardises for particle shape and density. By definition the aerodynamic diameter of a particle is the diameter of a sphere with unit density having the same terminal settling velocity as the particle in consideratimi. Only for aqueous droplets with a spherical shape and unit density the aerodynamic diameter equals the geometric diameter. For non-spherical particles, the aerodynamic diameter can be expressed in terms of equivalent volume diameter (De), particle shape factor (x) and particle density (p) (see definitions) Da = De.(p/x)° ... 

Figure 7.15. The way in which a cluster grows determines the overall ruggedness of the profile and that, in turn can affect the aerodynamic behaviour of the cluster, a) Simulated clusters grown using various probabilities that a wandering subunit will join the cluster, b) Real fumed thorium dioxide a omerates, all having the same aerodynamic diameter, but different boundary fractal dimensions as shown.

J, M. Buchlin, Aerodynamic Behaviour of Liquid Spray-Design Method of Water Spray Curtain, von Karman Institute, Rhode Saint Genese, Belgium 1980, Test Report No. 171. 

Particle density is an important parameter in defining the aerodynamic behaviour of airborne particles. Small quantities of selected batches (ca. Ig of FS3, FS4, FS5 and FS6) were placed in the sample chamber of a helium pycnometer (model 1305 Multivolume Helium Pycnometer, Micromeritics Ltd, Basingstoke, UK), and the particle density determined from the volume of helium displaced, assuming there were no inaccessible voids within the particles. The four measurements (each of which was the mean of 4 to 6 separate determinations (Table 3)) were within the density range of 2.91 to 3.26 X 1Q3 kg m-3 quoted for natrojarosite. These studies confirm the validity of the x-ray diffraction measurements, and also indicated that the particles were substantially free of internal voids. 

Custom-made SFD towers and apparatuses have been designed, built and improved to produce nearly monodisperse, low-density lyophilisate powders suitable for pulmonary dmg delivery. Spray-freeze-dried particles were characterized regarding their mean geometric particle size, aerodynamic behaviour, surface morphology and interior structure, API (protein) stabihty, powder flowability and reconstitution characteristics. 

Griffiths, W.D. and Vaughn, N.P (1986). The aerodynamic behaviour of cylindrical and spheroidal particles when settling under gravity. J Aerosol Sci 17 53-65. 

In addition, the cumulative size distribution obtained for pure micron-ized and supercritically produced powders, combined with computation of the aerodynamic diameter according to Eqs. (2) and (3), shows that FPF of supercritically produced particles is about 50%, twice as much as FPF for micronized powder and close to the dispersion efficiency found with lactose (76). The correct values for the total emitted dose of drug particles also were confirmed. In all cases, the state of dispersion for the different formulations was correctly predicted and the results obtained showed good agreement with the cascade impactor measurements made on the same samples. Therefore laser diffraction has distinct advantages over impactor techniques with respect to the speed and reproducibility of measurements and can be used as a complementary method for analysis of aerosol behaviour of different formulations. 

Inhaled particles vary both in shape and density and these factors affect their capacity to be deposited by sedimentation. The behaviour of such particles can be determined by converting their actual diameter(s) to their aerodynamic diameters). What does this mean Imagine a low-density particle of irregular shape - this will be characterized by a certain terminal velocity as it settles in air. The aerodynamic diameter of the particle is defined as the actual diameter of a spherical particle of unit density with the same terminal velocity. 

Skinner LB, Barnes AC, Crichton W (2006) Novel behaviour and structure of new glasses of the type Ba-Al-0 and Ba-Al-Ti-0 produced by aerodynamic levitation and laser heating. J Phys Condens Matter 18(32) L407-L414... 

As well as SANS measurements, a separate systematic study of the oscillatory behaviour of AY20 and AY30 was performed in order to test for the occurrence of a polyamorphic rotor. These measurements were taken on the aerodynamic levita-tor setup at the University of Bristol. Sample temperatures were again measured using a single wave pyrometer and videos were taken from two angles (Fig. 5.4). 

S. Heidenreich, H. Buttner, F. Ebert, Investigations in the behaviour of an aerodynamic particle sizer and its applicability to calibrate an optical particle counter . Part. Part. Syst. Charact., 12, 1995, pp. 304—308. 

Two types of equation are needed to compute the network myoelastic eqmtions that describe the physical behaviour of the walls of the pipes and aerodynamic eqmtions that describe the evolution of the movements and pressures of the air in the network. The variables for these equations are specified by means of 29 parameters that metaphorically describe the actions of the vocal tract muscles and organs, such as cricothyroid, styloglossus, orbicularis oris and masseter, to cite but four. This s)mthesiser is capable of producing utterances with an... 

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