Local Particle Deposition

Numerous studies have been carried out in the last decades to obtain detailed information about collection efficiencies and deposition patterns on a subregional level within the respiratory system. A complete overview is beyond the scope of the present chapter, but the studies introduced in the following discussion should give the reader an idea about approaches and results. 

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Local Deposition Within the Tracheobronchiolar and Alveolar Region 

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Bell, K.A. (1978). Local particle deposition in respiratory airway models. In Recent Developments in Aerosol Science (Shaw, D.T., Ed.). Wiley New York, pp. 97-134. 

Second, the a-particles deposit energy locally, breaking many bonds and causiag much tissue damage. 

From comparison of the optical properties of particles deposited on the same substrate and differing by their organization (Figs. 7 and 8) it can be concluded that the appearance of the resonance peak at 3.8 eV is due to the self-organization of the particles in a hexagonal network. This can be interpreted in terms of mutual dipolar interactions between particles. The local electric field results from dipolar interactions induced by particles at a given distance from each other. Near the nanocrystals, the field consists of the ap-... 

A shadow-mask technique has been applied for the local metal deposition to exclude metal residues on other designs processed on the same wafer (Fig. 4.2b). Such metal residues may be caused by imperfections in the patterned resist due to topographical features on the processed CMOS wafers or dust particles. The metal film is only deposited in those areas on the wafer, where it is needed for electrode coverage on the microhotplates. This also renders the lift-off process easier since no closed metal film is formed on the wafer, so that the acetone has a large surface to attack the photoresist. Another advantage of the local metal lift-off process is its full compatibility with the fabrication sequence of chemical sensors based on other transducer principles [20]. 

The deposition of silver in tissues is the result of the precipitation of insoluble silver salts, such as silver chloride and silver phosphate. These insoluble silver salts appear to be transformed into soluble silver sulfide albuminates, to bind to or form complexes with amino or carboxyl groups in RNA, DNA, and proteins, or to be reduced to metallic silver by ascorbic acid or catecholamines (Danscher 1981). The blue or gray discoloration of skin exposed to ultraviolet light in humans with argyria may be caused by the photoreduction of silver chloride to metallic silver. The metallic silver is then oxidized by tissue and bound as black silver sulfide (Danscher 1981). Bucklet et al. (1965) identified silver particles deposited in the dermis of a woman with localized argyria as being composed of silver sulfide. 

In a similar manner, during the process of the existing metal particles growth and the deposition of new species using cathodically biased electrode in a solution of metal ions, the growing metal phase will be also localized at the sites of the surface exposure of the continuous donor centers. The reason for this is that namely these sites possess substantially enhanced electrocatalytic activity in comparison with the stoichiometric oxide surface and exhibit the properties of current channels non-restricted by the Schottky barrier at the interface with the electrolyte. Actually, a peculiar decoration of the sites of donor centers accumulation and donor clusters localization by the metal nanoparticles takes place in the dark processes of metal particle deposition onto the surface of the chemically inert wide-band-gap oxides. The increased electrocatalytic activity of the wide-band-gap semiconductor electrodes resulted from the deposition of metal nanoparticles on their surface may be also regarded as a kind of such decoration . 

It is interesting to speculate whether, in spite of the lung s attempts to produce more fluids at the site of foreign particle deposition, fiber dissolution could increase the pH of the local lung fluids so that they sufficiently become saturated with fibrous silicates, thereby limiting further dissolution. 

Balashazy I, Hofman W, Heistracher T. Computation of local enhancement factors for the quantification of particle deposition patterns in airway bifurcations. J Aerosol... 

In addition to analytical applications for monitoring surftice structures and dynamics STM can also be used as a tool for the deliberate modification of electrode surfaces on the mesoscopic scale. By applying appropriate signals to an STM tip, local metal-deposition reactions can be induced from metal-ion-containing solutions [12, 15, 16]. As an example. Fig. 8 shows a platinum particle on an HOPG surface, which was... 

Velocity and concentration profiles are two important parameters often needed by the operator of slurry handling equipment. Several experimental techniques and mathematical models have been developed to predict these profiles. The aim of this chapter is to give the reader an overall picture of various experimental techniques and models used to measure and predict particle velocity and concentration distributions in slurry pipelines. I begin with a brief discussion of flow behavior in horizontal slurry pipelines, followed by a revision of the important correlations used to predict the critical deposit velocity. In the second part, I discuss various methods for measuring solids concentration in slurry pipelines. In the third part, I summarize methods for measuring bulk and local particle velocity. Finally, I review models for predicting solids concentration profiles in horizontal slurry pipelines. 

In this context the number of particles depositing for given hydraulic conditions (C — Ceq) must be determined. This means that the characteristics of the particulates must be correlated to local parameters describing the turbulent flow field. This leads to a critical sedimentation velocity i s.cr for a particle. It is derived on the basis of an energy balance the potential energy loss attributable to settling in a non-turbulent system must equal the turbulent kinetic energy that must be imparted on the particle in a turbulent flow system to prevent sedimentation (29). 

Wippermann developed a galvanic deposition of noble metals on carbon for usage in fuel cells [3]. Noble metal cluster such as platinum ion deposits on carbon particles which is in the contact interface of conducting carbon and electrolyte due to delivery of electrons via contact interface. Schindler developed the deposition of metal cluster on various metals and semiconductor substrate [3]. By cathodic accumulation of metal atoms on a conducting STM tip due to anodic dissolution, local enrichment can be achieved which allows localized cathodic deposition. Kolb applies localized deposition on the metal cluster on substrate by direct transferring of atoms from the STM tip [4]. 

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