Particles, durability

Most toxicological studies focus on the toxicity or solubility behavior of a particular sample of a given mineral such as chrysotile, tremolite, or talc. They do not tend to examine the role that variations in morphology, trace element content, accessory minerals, and other characteristics between the same mineral from different samples in the same geologic locality, and between samples from different geologic localities, can play in in vitro and in vivo biodurability, and therefore toxicity. These parameters have been demonstrated to play important roles in the rate at which other minerals, such as sulfides, weather under environmental conditions (see summary in Plumlee, 1999), and so are also likely to be important for particle durability in vivo. 

Similarly, for the analysis of polymers using high-temperature solvents, the important concern is column stability and durability. Eor this reason, 10-/am particles are the best column choice. Waters Styragel HT columns are designed for this kind of application. Similarly, these columns are also more tolerant to eluent changes. Therefore, these columns are also recommended... 

More advanced insulations are also under development. These insulations, sometimes called superinsulations, have R that exceed 20 fthh-°F/Btu-m. This can be accomplished with encapsulated fine powders in an evacuated space. Superinsulations have been used commercially in the walls of refrigerators and freezers. The encapsulating film, which is usually plastic film, metallized film, or a combination, provides a barrier to the inward diffusion of air and water that would result in loss of the vacuum. The effective life of such insulations depends on the effectiveness of the encapsulating material. A number of powders, including silica, milled perlite, and calcium silicate powder, have been used as filler in evacuated superinsulations. In general, the smaller the particle size, the more effective and durable the insulation packet. Evacuated multilayer reflective insulations have been used in space applications in past years. 

The present study was initiated to understand the causes of large differences in perfonnance of various catalyst formulations after accelerated thermal aging on an engine dynamometer. In particular, we wished to determine whether performance charaderistics were related to noble metal dispersion (i.e. noble metal surface area), as previous studies have suggested that the thermal durability of alumina-supported Pd catalysts is due to high-temperature spreading or re-dispersion of Pd particles [20-25]. 

The durability of the catalytic system was investigated by employing it in five successive hydrogenations. Similar TOFs were observed due to the water solubihty of the protective agent which retains nanoparticles in aqueous phase. The comparative TEM studies show that (i) the average particle size was 2.2 0.2 nm (ii) the coimter anion of the surfactant does not allow a major influence on the size and (iii) nanoparticle suspensions have a similar size distribution after catalysis. 

The question of durability of the mitigation system arises not only from the need for lifetime operation in the house, but also from concerns about the environment to which the SSD system is subjected.13 15 Soil gas is often very humid, causing condensation problems in the piping and the fan of the mitigation system. Also, particles can be drawn from the gravel bed or soil they in turn may line the pipes and deposit on the fan or possibly interfere with the fan bearings. 

By choosing the appropriate chemical structures, chains that span filler particles in a polymer-based composite can be designed so that they are either durable, breakable irreversibly, or breakable reversibly [242-245]. 

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