Size-frequency distribution combination

Thru a combination of sedimentation and transmission measurements, a particle size distribution can be found. Tranquil settling of a dispersion of non-uniform particles will result in a separation of particles according to size so that transmission measurements at known distances below the surface at selected time intervals, will, with Stokes law, give the concn of particles of known diameter. Thus, a size frequency distribution can be obtained... 

Calculation of mean crystallite size, lattice strain and frequency distributions of crystallite sizes from the same XRD line-profiles used for crystallinity determinations. In addition to the application of the Scherrer equation, two single-line methods were used the variance method of Wilson (1963) (Akai and To th 1983 Nieto and Smchez-Navas 1994), and the Voigt method of Langford (1978) in combination with single-line Fourier analysis (Akai et al. 1996, 1997, 2000 Warr 1996 Jiang et al. 1997 Li et al. 

Clearance is a critical parameter because of its role in determining a drug s dose size and frequency. First-pass clearance in combination with absorption determines a compound s bioavailability. Clearance and absorption in combination with potency determine dose size. Clearance and volume of distribution determine half-life, and thus dosing frequency. 

The timing, frequency and location of sampling, as well as the type, number and size of specimens to be taken, is usually determined by a combination of factors, i.e., strategy of ESBs, characterization type, sample chemical concentration, distribution, abundance and availability of the population and/or materials to be sampled, seasonal variability, storage room, ease of collection and transport, costs, etc. (13). 

Laser Doppler velocimetry has been combined with acoustic excitation to allow the derivation of the relaxation time for particles, from which the aerodynamic diameter can be calculated [132-136], The particle relaxation time is derived from the velocity amplitude of the aerosol particle and that of the medium while the aerosol is subjected to acoustic excitation of a known frequency. A differential laser Doppler velocimeter is used to measure the velocity amplitude of the particle, and a microphone is used to measure the velocity amplitude of the medium. The aerodynamic diameter of the particle can be derived from the relaxation time and the known particle density. The method can be applied to real-time in situ measurement of the size distribution of an aerosol containing both solid and liquid droplets in the diameter range of 0.1 -10 pm. 

Attempts have been made to correlate this behavior with the ring sizes and average T-O-T angles present in zeolites of different topologies [300]. However, the observed frequency dependencies were not fairly uniform. In particular, for A-type zeolites a trend reversed to that for faujasites has been observed by changing the nsi/n i ratio systematically [290]. Hence, the frequency shifts obviously arise from different effects of structural changes, altered nature of normal modes, and electron density distribution and from combinations of these effects. Instead of the band shift observed for aliunimun-rich samples, for highly dealuminated faujasites the band width of the most prominent peak was discovered to reflect the aliuninum content at low levels [295]. 

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