Fractional deposition

Bennett, W.D. 1991. Aerosolized drug delivery fractional deposition of inhaled particles. J. Aerosol Med. 7 223-228. 

It was also assumed that the production ratios of the three radionuclides were the same as the ratios given for weapon fission yields (12). For each of the three storms and the reported nuclear explosions for the period, an analysis of the fractional deposition by event was made for each collection site along, and by regions of, the California coast. Based on these assumptions, the fraction of 140Ba from the most recent atmospheric nuclear explosion before each storm was 1.00. The 140Ba deposition on storm date was extrapolated to the explosion date. The initial... 

The increased deposition of the two strontium radioisotopes from Goleta southward restores the 140Ba/89Sr ratio to the values found at the northern sites. The fractional deposition of 89Sr by event is also similar to the fractions observed at the northern sites. However, the lack of "Sr from China-3 at Piedras Blancas and Vandenberg AFB seems to change to an excess of about 14-43% from Goleta to La Jolla. 

Fractional Deposition by Event Prefrontal Rainfall Total Storm Rainfall... 

Region of Coast Product Fractional Deposition by Event ... 

The process of diffusion of heavy metals in seawater depends on their state. The dissolved fraction of heavy metals (ip) takes part in the biogeochemical processes more intensively than suspended particles (e). But unlike suspended particles, the heavy metals fall out more rapidly to the sediment. A description of the entire spectrum of these processes in the framework of this study is impossible. Therefore, block MMT describes processes that can be estimated. The transport of heavy metals in seawater includes absorption of the dissolved fraction ip by plankton (11%) and by nekton (H%), sedimentation of the solid fraction (//) ), deposition with detritus (11%), adsorption by detritophages from bottom sediments (Iff), and release from bottom sediments owing to diffusion (Hef). As a result, the dynamic equations for heavy metals become ... 

The fraction deposited is related to the diffusivity by Gormley Kennedy s (1949) equation... 

Fig. 1.14. Fractional deposition of particles in the respiratory tract, and in the T-B region of the tract (15 breaths/min by mouth, tidal volume, 11). Calculations of Yu Diu, 1982, full lines and Egan Nixon, dashed lines. Experimental results of Tu Knutson, 1984, Schiller et al., 1988,0 Chamberlain et al., 1978, x.

The fraction deposited in the TB and P regions varies between subjects, but in a single subject, P/(TB + P) varies systematically with particle size (Lippmann etal., 1980 Stahlhofen etal., 1980). 

The lines in Fig. 7.4 are the results of theoretical calculations, using models of the respiratory tract (Yu Diu, 1982). The points are measurements with radioactive aerosols. Numerous other determinations of fractional deposition in the whole tract have been made, using non-radioactive methods to count the number of particles in the inhaled and exhaled air (Heyder et al., 1986 Schiller et al., 1988). Fractional deposition is least for particles of about 0.2 to 0.5 m diameter. Table 7.1 shows that the combined effect of sedimentation and Brownian motion is then at a minimum. 

A comparison of the results with other data on the deposition of submicrometre aerosols, all related to a tidal volume of 11, is shown in Fig. 1.14. Although the density of the lead particles was greater than that of the other particles, the fractional deposition was similar, except possibly for the 0.5 pm size, because deposition was by Brownian motion. The percentage deposition increases for particles of diameter less than 0.1 /urn, and this means increased uptake of lead, relative to a given PbA, for persons exposed to non-aggregated aerosol, as found alongside major roads. 

In solution, the UV absorption characteristics of polygermanes may be different from those in the solid state. Poly(dihexyl)germane in solution has a kmax value of 327 nm, whereas the same polymer fraction deposited as a thin film on a quartz plate exhibits two... 

As an example of thin-foil analysis in the SEM, samples of the mineral standard kaolinite (<2 pm fraction, KGa-2, Source Clay Minerals Repository) were dispersed on TEM grids and analyzed using a JEOL JSM 6400 SEM under the control of an automated Noran Voyager EDS system equipped with a thin-window EDS detector.93 For comparison, EDS spectra were also collected using the same instrument for the kaolinite size fractions deposited on polycarbonate filters, fixed to SEM... 

Sulphate present in the gel could be accommodated as interlayer anions associated with AFm layers. C-S-H can, however, take up CaS04 in the absence of AH or Fe, and thus of AFm layers. Odler (017) showed that CaS04 thus bound was very readily removed, and suggested that the Ca and S04 ions were adsorbed. The and Na ions that are found in the cement gel by X-ray microanalysis are partly the result of deposition from the pore solution when the latter evaporates during specimen preparation or in the high vacuum of the instrument, and these, too, with equivalent amounts of OH , may be adsorbed after deducting the fractions deposited from the pore solution, the K/Ca and Na/Ca ratios in the gel are typically 0.01 and <0.01, respectively (Section 7.5.2). 

Ciliary action removes deposited particles from both the bronchi and bronchioles. Though it is generally thought that mucocilliary action rapidly transports most particles deposited here toward the pharynx, a fraction of these particles are cleared more slowly. Evidence for this is found in human studies. For humans, retention of particles deposited in the lungs (BB and bb) is apparently biphasic. The slow action of the cilia may remove as many as half of the bronchi- and bronchiole-deposited particles. In human bronchi and bronchiole regions, mucus moves more slowly the closer to the alveoli it is. For the faster compartment it has been estimated that it takes about 2 days for particles to travel from the bronchioles to the bronchi and 10 days from the bronchi to the pharynx. The second (slower) compartment is assumed to have approximately equal fractions deposited between BB2 and bb2 and both with clearance... 

The weight fraction oversize can be determined if the weight fraction deposited is measured for different values of the variables S, R and t. 

Figure 1 Hypothetical collection efficiency of a stage of an impactor. Fraction deposited plotted against particle size. The step function indicates the theoretical deposition, and the curve indicates the practical characteristics.

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