Precursors gaseous

Fig. 3.34 LDA of the microarray signal patterns obtained in practical KAMINA tests to detect gaseous precursors of smoldering fires through overheated cable insulation. Prior to the LDA the measured resistances of the sensor segments were normalized to the median of all sensor segments and the number of variables was reduced by a Principal Component Analysis (PCA) to cutback the noise. Clear distinction is achieved between clean air...

Cs occurs in crater ejecta and fallout debris as a surface-adsorbed, soluble radionuclide, owing to its gaseous precursor. The behavior of... 

Ce, 147Nd, and radionuclides with gaseous precursors correlate linearly and have nearly the same correlation parameters as have been observed in air bursts. 

The analysis was made on the assumptions that the differences in gaseous-precursor fission products resulted in a potential fractionation of the three alkaline-earth radionuclides and the radioaerosols participating in the precipitation processes in the Pacific cyclones over the... 

Abstract Gaseous and particulate emissions from vehicles represent a major source of atmospheric pollution in cities. Recent research shows evidence of, along with the primary emissions from motor exhaust, important contributions from secondary (due to traffic-related organic/inorganic gaseous precursors) and primary particles due to wear and resuspension processes. Besides new and more effective (for NO emissions) technologies, non-technological measures from local authorities are needed to improve urban air quality in Europe. 

Less-refractory fission products condense later onto the surface of the particles. Those with gaseous precursors, for example Sr and 137Cs, condense as they are formed by decay of their parent nuclides. The... 

CVD is a flexible and simple process to produce supported catalysts [16]. In a typical CVD process (see Figure 3.4), a substrate is attacked by one or more gaseous precursors that react and/or decompose on the substrate surface to produce the chosen deposit. 

Alternative approaches for GaN MBE, involving gaseous precursors which are sufficiently reactive to achieve growth without dissociation by plasmas, have been developed. RMBE has the advantages of being less complicated and therefore less expensive, and easy to control, and it is inherently free of ions and sputtering effects. 

Sulfite Oxidase. This enzyme, isolated from bovine (26, 27) and chicken liver (28), catalyzes the oxidation of sulfite to sulfate. This is possibly a crucial function in animals as S032" (or S02, its gaseous precursor) is toxic while S042" is relatively innocuous. For example, one of the first signs of molybdenum deficiency in rats is a greatly increased susceptibility to S02 poisoning (28). In addition, a human child bom without sulfite oxidase activity did not survive for very long (29). 

Particle formation events from gaseous precursors are observed frequently almost everywhere in the troposphere, both in polluted cities and remote clean areas [4]. It is likely that different nucleation mechanisms are at work in different conditions, but no formation mechanism has been identified so far. It is, however, clear that particles are formed by nucleation of a multicomponent vapor mixture. Water vapor is the most abundant condensable gas in the atmosphere, but it can not form particles on its own homogeneous nucleation requires such a high supersaturation, that heterogeneous nucleation on omnipresent pre-existing particles always starts first and consumes the vapor. However, vapor that is un-... 

Recently, afluidized-bed approach has been developed wherein SiHa and H2 gases are fed into the bottom of a vertical reactor held at a temperature >600°C. Silicon seed crystals are suspended in the chamber due to the gas flow, and decomposition of the gaseous precursor causes the nucleation/growth of silicon on the surface of the seeds. When grown to large sizes, the particles no longer remain suspended and are collected at the bottom of the reactor. 

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