Mass distribution, particulate

Eldering, A., and R. M. Glasgow, Short-Term Particulate Matter Mass and Aerosol-Size Distribution Measurements Transient Pollution Episodes and Bimodal Aerosol-Mass Distributions, Atmos. Environ., 32, 2017-2024 (1998). 

Recently, Kulicke et al. [145] applied the principle of Flow-Field-Flow-Frac-tionation (F4) in combination with multi angle laser light scattering (MALLS) to characterize PDADMAC. Differential and integral molar mass distributions have been published for PDADMAC. One advantage of this method seems to be that it can be extended to the investigation of the mass distribution of aggregated and particulate components. 

In Figure 10.30 the survival rate of the total sedimentary mass for the different Phanerozoic systems is plotted and compared with survival rates for the total carbonate and dolomite mass distribution. The difference between the two latter survival rates for each system is the mass of limestone surviving per unit of time. Equation 10.1 is the log linear relationship for the total sedimentary mass, and implies a 130 million year half-life for the post-Devonian mass, and for a constant sediment mass with a constant probability of destruction, a mean sedimentation rate since post-Devonian time of about 100 x 1014 g y 1. The modem global erosional flux is 200 x 1014 g y-1, of which about 15% is particulate and dissolved carbonate. Although the data are less reliable for the survival rate of Phanerozoic carbonate sediments than for the total sedimentary mass, a best log linear fit to the post-Permian preserved mass of carbonate rocks is... 

If the number size distribution of a particulate system is found to be lognormal, equations (2.77) to (2.80) can be used to determine other mean sizes. For example, the volume-moment mean size is the mean size of a volume (mass) distribution ... 

Figure 2 Representative example of a mass distribution of ambient particulate matter as a function of particle diameter. Mass distribution per particle size interval is shown as Amass/A(logDa) (in Rgni ) plotted against particle size (ZJa) in micrometers. Tbe figure also shows the range of aerosol sizes included in various methods of aerosol measurement wide range aerosol classifiers (WRAC), total suspended particulate (TSP) samplers, PMjo and PM25 samplers (source Lippman and Schlesinger, 2000) (reproduced by permission of Annual Reviews from Annual Review of Public Health 2000, 21, 309-333).

Macromolecular or particulate samples fractionated by the FFF are usually not uniform but exhibit a distribution of the concerned extensive or intensive parameter [8] or, in other words, a polydispersity. Molar mass distribution (MMD), sometimes called molecular weight distribution (MWD), or particle size distribution (PSD) describes the relative proportion of each molar mass (molecular weight), M, or particle size (diameter), d, species composing the sample. This proportion can be expressed as a number of the macromolecules or particles of a given molar mass or diameter, respectively, relative to the number of aU macromolecules or particles in the sample ... 

Urban aerosols are mixtures of primary particulate emissions from industries, transportation, power generation, and natural sources and secondary material formed by gas-to-particle conversion mechanisms. The number distribution is dominated by particles smaller than 0.1 pm, while most of the surface area is in the 0.1-0.5 pm size range. On the contrary, the aerosol mass distribution usually has two distinct modes, one in the submicrometer regime (referred to as the accumulation mode ) and the other in the coarse-particle regime (Figure 8.11). 

Such structures are known as porous electrodes and they behave quite differently from the effectively planar electrodes used in most other areas of applied electrochemistry. The porous electrode is a mass of particulate reactants (sometimes with additives) with many random and tortuous electrolyte channels between. Real porous electrodes cannot be modelled but their behaviour can be understood qualitatively using a simplified model shown in Fig. M.5 in fact, there are two distinct situations which arise. In the first (Fig. 11.5(a)) the electroactive species is a good electronic conductor (e.g. a metal or lead dioxide here, the electrode reaction will occur initially on the face of the porous electrode in contact with the electrolyte but at the same time, and probably contributing more to the total current, the reaction will occur inside the pore not, however, along the whole depth of the pore because of the fR drop in solution. The potential and current distribution will depend on both the kinetics of electron transfer and the resistance of the electrolyte phase. A quantitative treatment of the straight, circular pore approximation allows a calculation of the penetration depth (the distance down the pore where reaction occurs to a significant extent) and it is found to increase linearly with electrolyte conductivity and the radius of... 

The most important material component of the environment with respect to degradation of electronic devices is particles (Sinclair, 1988 Frankenthal et al., 1993). Most of the mass of particulate matter in the atmosphere exists in the size range 0.1 to 15 pm. Within this range, the mass exhibits a bimodal distribution. Particles 2.5 -15 pm are largely derived from natural materials and are usually called coarse particles, while particles 0.1 -2.5 pm, usually called fine particles, are primarily derived from anthro-... 

It is based on the principle that particles, suspended at low concentration in an electrolyte solution, are detected upon their passage through a small orifice in an insulating wall by the modulation of an electrical field existing within the orifice. This electrical modulation is sensed as a voltage pulse for each particle, the height of which is proportional to the volume of the particle. This is very convenient since a measurement yields directly a number distribution of equivalent volume diameters. This distribution is, in turn, easily converted to a volume-based distribution of equivalent volume diameters. Since the volume of a particle is directly related to its mass through the density, this distribution is identical to a mass distribution and, thus, most relevant to characterize a lot of particulate material. Therefore, in our opinion standardisation and... 

Figure 11.1 Diesel particulate size distribution. Solid line number distribution. Broken line mass distribution. Adapted from Majewski and Khair. ...

Figure 1 shows the particulate loading of a pipe containing gas and particulates where the nonuniformity induced by a disturbance, ie, a 90° bend, is obvious (2). A profile of concentration gradients in a long, straight, horizontal pipe containing suspended soHds is shown in Figure 2. Segregation occurs as a result of particle mass. Certain impurities, eg, metal-rich particulates, however, occur near the bottom of the pipe others, eg, oily flocculates, occur near the top (3). Moreover, the distribution may be affected by Hquid-velocity disturbances and pipe roughness.

Aerosol Dynamics. Inclusion of a description of aerosol dynamics within air quaUty models is of primary importance because of the health effects associated with fine particles in the atmosphere, visibiUty deterioration, and the acid deposition problem. Aerosol dynamics differ markedly from gaseous pollutant dynamics in that particles come in a continuous distribution of sizes and can coagulate, evaporate, grow in size by condensation, be formed by nucleation, or be deposited by sedimentation. Furthermore, the species mass concentration alone does not fliUy characterize the aerosol. The particle size distribution, which changes as a function of time, and size-dependent composition determine the fate of particulate air pollutants and their... 

Fig. 6. Size distribution of an urban aerosol showing the three modes containing much of the aerosol mass. The fine mode contains particles produced by condensation of low volatility gases. The mid-range, or accumulation mode, results from coagulation of smaller aerosols and condensation of gases on preexisting particles. Coarse particulates, the largest aerosols, are usually generated mechanically.

The complete characterization of a particulate material requires development of a functional relationship between crystal size and population or mass. The functional relationship may assume an analytical form (7), but more frequentiy it is necessary to work with data that do not fit such expressions. As such detail may be cumbersome or unavailable for a crystalline product, the material may be more simply (and less completely) described in terms of a single crystal size and a spread of the distribution about that specified dimension. 

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