Diameters, particle calculated

In order to find if the uniform-layer approximation can be used in our gradient-layer model, we simulated the i (6) curves of the layer of 40-nm-diameter particles, calculating n z) from the volume fraction (Eq. 5) and the Lorentz Lorenz formula (Eq. 6) (using the refractive index values 1.450 for silica, 1.333 for water and 1.000 for air), and evaluated these simulated reflectance curves by the uniform-layer method. The results are shown in Fig. 3. It is evident that the uniform-layer method can... 

Particle Size. The soHds in a fluidized bed are never identical in size and foUow a particle size distribution. An average particle diameter, is generally used for design. It is necessary to give relatively more emphasis to the low end of the particle size distribution (fines), which is done by using the surface mean diameter, to calculate an average particle size ... 

Table VII contains the weight-average particle diameters as calculated by this technique for all the standards employed using Column Set I. There is some difference between the values of variance used to obtain these averages and those cited in Table V. This is in fact due to the necessity to correct for skewness by...

The diameter averages calculated from the mixt ire rule are given in Table VI. While the first row entries for each mixture are the true values, the values that would be obtained from the analysis of the bimodal chromatograms should be compared with the third row entries since these account not only for the less than satisfactory calculations for the 183 nm sample chromatogram, but also for the incomplete recovery of the l83 nm particles. 

It is well known that enhanced deposition in the first few airways occurs due to the turbulence produced. Turbulent diffusion is accounted for by using factors (ratio of observed deposition to calculated diffusion deposition) to correct the diffusion deposition. These had formerly been measured by Martin and Jacobi (1972) in a dichotomous plastic model of the upper airways. The data used here are from measurements performed by Cohen (1986) using hollow casts of the upper bronchial tree which included a larynx. This cast was tested using cyclic flow with deposition measured for 0.03, 0.15 and 0.20 urn diameter particles. Her turbulent diffusion factors are used in the calculation here (14 for generation 0, and 2 for generations 1 to 6). 

The deposition of ultrafine particles has been measured in replicate hollow casts of the human tracheobronchial tree. The deposition pattern and efficiency are critical determinants of the radiation dose from the short lived decay products of Rn-222. The experimental deposition efficiency for the six airway generations just beyond the trachea was about twice the value calculated if uniform deposition from laminar flow is assumed. The measured deposition was greater at bifurcations than along the airway lengths for 0.2 and 0.15 ym diameter particles ... 

Figure 2. Nanodiffraction patterns from small gold particles for an incident beam diameter of 1-2 nm (a) Observed for a particle of 2-3 nm diameter showing twinning on two planes (b) Observed for a multiply twinned particle of 1.5 nm diameter. (c) Calculated for a model multiply twinned particle. The black spots in (a) and (b) are the small mirrors in the optical analyser system used as detectors for imaging.

Figure 3.20 The effective hard sphere diameter, r0, calculated from Equation (3.65) for 100 nm radius particles with ( = 50 mV...

Aerosol for chemical analysis was sampled in the air monitoring trailer through a 1.3 cm ID stainless steel pipe. The air inlet was about 1 m above the roof of the trailer, a total of 4 m above the ground. Loss of 0.1 pm diameter particles to the walls due to turbulent diffusion was calculated to be less than 1% using the method of Friedlander (11). A cyclone preseparator (12) was used to separate the coarse (D > 2 pm) aerosol from the airstream so that only the fine (D <2 pm) aerosol would be collected for analysis. The cyclone was operated at 26-30 liters per minute (1pm) and was cleaned every 8-10 weeks. 

Using equation (4) the distance that a solute band must pass along a column before a sample, injected at the center of the packing, is evenly spread across its diameter, was calculated for columns packed with different sized particles. 

Employing equation (24), the minimum column diameter was calculated for a column 10 cm long packed with particles of different diameters. The standard deviation of the extra column dispersion was assumed to be 5, 10 and 15 microlitres respectively, values that embrace those that would be... 

Employing Equation (2) and the data given in table l, the optimum particle diameter was calculated for the preparative separation of a solute where the separation ratio of the critical pair ranged from l.01 to 1.50 at inlet pressures of 1,10,100,1,000 and 10,000 p.s.i. The results obtained are shown in figure I... 

Table I. Mean particle diameter and calculated surface area of encapsulated orange oils...

Powder Code Voltage Used (V) Mean particle Diameter ( i) Calculated Surface Area... 

The number distribution is derived naturally from the mass distribution. Knowing the drug particle diameter, the total mass of drug of that diameter, particle geometry, and the density of the drug, one can calculate the number of particles represented by each particle size group.1,3 Because the mass distribution was normalized to the unit dose of 0.1 mg, the number distribution shown represents the number of particles in a unit dose. 

On the other hand, if the total surface of a unit-weight of the material (i.e. specific surface) is desired, we may utilize the average diameter as calculated by Eq (3-10). If the particles are regarded as spheres or rectangular parallelopipeds, then the diameter may be determined by means of Eq (3-6). 

In practice the average diameter is calculated in the usual way (see Table 4). Then the thickness of enough particles to provide a fair... 

Crystallite size of PcFe particles. The mean crystallite diameters of the PcFe particles calculated from the broadening of the (100) and (102) reflexions, are given in Table III. It is seen that the crystallite sizes in both directions are similar which suggest that there is no significant anisotropy in the shape of the PcFe crystallites. 

The data of Table II also indicate that for a given PcFe content the crystallite size is greater on the activated carbon. This result however does not mean that the actual particle size of PcFe is greater on the activated carbon. As will be shown below, the particles of PcFe may contain several crystallites. The mean crystallite diameter 3g calculated from the (100) reflexion is compared to the mean particle size dg determined from the water uptake measurements in Figure 4 for both carbon substrates. It appears that 3fi and 3s are in fairly good agreement in the case of the heterogeneous carbon... 

Using Stokes Law, calculate the amount of time needed to settle 1/1,000,000 m diameter particles 1 m depth. How much faster would the particles settle if their diameter was increased to 3/1,000,000 m Finally, flocculation is found to increase the effective particle diameter to 1/100,000 m, calculate die time needed to settle these particles 1 m depth (consider the density of the particle to be 2500 kg m-3). 

Because of the fact that the Nusselt number and the Peclet number are not simply expressed in terms of the particle diameter it is convenient to use them as intermediate variables in the calculation. Since the mass velocity is fixed, the Reynolds number and the Nusselt number are determined by the particle diameter. The calculation proceeds by finding the values of r2 from selected values of dp, as determined from ki, and fc2 separately. By inverse interpolation, the value of dp that makes the two values of r2 equal is found. 

---