Leading particle effect

Hodgkins DG, Rogins TG, Hinkamp DL et al. 1991. The effect of airborne lead particle size on worker blood-lead levels An empirical study of battery workers. J Occup Med 33 1265-1273. 

Asami R, Atobe M, Fuchigami T (2006) Ultrasonic effects on electroorganic processes. Part 27. Electroreduction of acrylonitrile at suspended lead particle-electrode. Ultrason Sonochem 13 19-23, and the series... 

The effectiveness of the BSWS as a volume reduction unit depends largely on the solubility of the lead compounds in the washing medium, the efficiency of density separation for removing discrete lead particles, and the particle size distribution in the feed soil. 

A weakly bound state is necessarily nonrelativistic, v Za (see discussion of the electron in the field of a Coulomb center above). Hence, there are two small parameters in a weakly bound state, namely, the fine structure constant a. and nonrelativistic velocity v Za. In the leading approximation weakly bound states are essentially quantum mechanical systems, and do not require quantum field theory for their description. But a nonrelativistic quantum mechanical description does not provide an unambiguous way for calculation of higher order corrections, when recoil and many particle effects become important. On the other hand the Bethe-Salpeter equation provides an explicit quantum field theory framework for discussion of bound states, both weakly and strongly bound. Just due to generality of the Bethe-Salpeter formalism separation of the basic nonrelativistic dynamics for weakly bound states becomes difficult, and systematic extraction of high order corrections over a and V Za becomes prohibitively complicated. 

Table 2 shows the effect of temperature on the lead reduction. There is hardly any lead reduction when reaction temperature is less than 100°C. Presence of water during the reaction prevents agglomeration of hydroxyl phosphates, which facilitate the removal of lead particles. As discussed earlier, the removal of water during the reaction entrains the lead particles with the agglomerates of metallic hydroxyl phosphate. 

The functional groups in a molecule determine, to a considerable extent, whether its ion radical form can be the leading particle in the course of the reaction. The effect of substituents on the properties of the ion radical molecule has not yet been elucidated adequately. The main problem is to find out what groups should be introduced into the molecule to direct the reaction to the ion radical mechanism. At first, these groups should impart pronounced acceptor or donor properties to the molecule. Then these groups must be able to stabilize the ion radical produced. In case of anion radicals, such groups are ni-... 

Consider the collision of particles due to wake attraction, as shown in Fig. E3.1. It is assumed that (a) the motion of the leading particle is not affected by the approach of the trailing particle (b) particles are equal-sized, rigid, and spherical and (c) initially, the particles move nearly at their terminal velocities with a very small velocity difference and are separated by a characteristic distance Zo- An empirical relation can be used to describe the effects of the interparticle distance Z and particle Reynolds number Rep on the drag force of the trailing particle as... 

It is important to understand the dynamics of photogenerated electrons and holes and their role in semiconductor systems to facilitate the design and development of efficient photocatalysts (Anpo, 2002 Anpo and Che, 1999 Matsuoka and Anpo, 2005). As reported earlier (Anpo and Che, 1999), the presence of a small number of platinum particles on TiC>2 is known to strongly increase the yield of photoreactions. This effect is attributed to a migration of the photoformed electrons from the conduction band of TiC>2 to the platinum particles, whereas the holes remain in the valence band, leading to effective charge separation of the... 

The results demonstrate that nanometer wide cracks can have severe effects on the shock-to-detonation threshold. It might be tempting to conclude that the chemical reactions caused by these defects result from a velocity doubling as atoms are spalled into the crack. Indeed, we found that the velocities of the leading particles that are spalled into the crack by the shockwave had approximately twice the particle flow velocity in the shockwave, as predicted by the continuum theory. However, we also observed that when these high velocity molecules struck the opposite side of the crack, reactions were not induced immediately. Rather, the complex motions of the many atoms within the crack appears to seed the chemical reactions that ultimately cause detonation. These studies lay the foundation for additional studies with more complex models. 

Although lead pollution effectively began early in the history of mankind, the human input of this metal to the environment increased sharply in the twentieth eentury (Fergusson, 1990). For example, the burning of lead-supplemented fuels has caused the release into the atmosphere of huge quantities of lead-containing particles and aerosols (and their subsequent wet and dry deposition in waters and soils). 

A mechanism for the acceleratory stage based on the catalytic effect of colloidal lead particles would agree with the model used to explain photolysis of alkali azides. Hall and Williams showed that metal films in contact with lead azide alter the photodecomposition efficiency [96]. Alernatively, the acceleratory stage may result from an increased concentration of trapped nitrogen molecules diffusing to the surface. The deceleration is thought to result from a depletion of azide molecules in the near-surface regions [120]. 

It is knownis that small metallic particle effects arising from random depolarization factors in highly anisotropic metallic grains in ceramic samples can lead to artifacts in the infrared reflection (and absorption) spectrum. Since the samples used in the photoinduced absorption experiments are insulating micron sized crystallites embedded in an insulating medium, such small particle effects will not affect either the infrared spectrum or the photoinduced IR absorption spectrum where the measured AT/T is of order i0-3. 

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