Darken factor

Equilibrium data Adsorption isotherms evaluated from the three series of experiments are presented in Figure 3. From the equilibrium data the Darken factor sin p/31n a has been Isosteric adsorption heat q amounts about... 

Zeohte ciyst lite diffusivities for sorbed gases range from 10" to lO" " cmVs. These diffusivities generally show a strong increase with the adsorbate concentration that is accounted for by the Darken thermodynamic correction factor... 

Many other cations besides the norbomyl cation have nonclassical structures. Scheme 5.5 shows some examples which have been characterized by structural studies or by evidence derived from solvolysis reactions. To assist in interpretation of the nonclassical stmctures, the bond representing the bridging electron pair is darkened in a corresponding classical stmcture. Not surprisingly, the borderline between classical stmctures and nonclassical stmctures is blurred. There are two fundamental factors... 

In irradiated potatoes, especially in some varieties and as a function of cultivating conditions of the raw material, after-cooking darkening may occur. This discoloration is attributed to formation of ferric-phenolic complexes. This phenomenon depends on the iron content, and is related to increased polyphenol formation and reduced citric acid levels, which are influenced by agronomic and climatic factors. Various technological measures have been developed to prevent this after-cooking darkening [23]. 

Just as with organic combustion aerosols, the chemical and physical nature of inorganic solid substrates can have a dramatic impact on the photoreactivity of adsorbed PAH. In 1980, Korfmacher and co-workers reported that BaP, pyrene, and anthracene all pho-tolyzed efficiently in liquid solution but were resistant to photodegradation when adsorbed on coal fly ash. Subsequent studies confirmed this observation and revealed that the carbon content of the ash (and the associated darkening of color) is a key factor in establishing the photostability of these PAHs. Indeed, they were stabilized at relatively small percentages of carbon, e.g., 5% or less (Behymer and Hites, 1985, 1988 Yokley et al., 1986 Dunstan et al., 1989 Miller et al., 1990). 

There have been a few experiments related to the effect of illumination of the growth of CdS films. Simple heating of the deposition bath by absorption of the radiation is one obvious factor that can affect the deposition [68]. However, even in this case, other effects occur, since the color of the bath was reported to darken if UV (sunlight) illnmination was employed. Based on previous studies of illuminated CdS colloids when elemental Cd was formed, both as a film and in solution [69], as well as the known tendency of ZnS to undergo reduction to metallic Zn under UV illumination, this darkening may be assumed to be caused by elemental Cd. There are several possible mechanisms that may explain snch an effect re-dnction of the CdS by photogenerated electrons is one possibility. 

Sunlight is a factor which hastens the decomposition of smokeless powder. Experiments carried out by D. Berthelot and Gaudechon [60] showed that powders containing various types of stabilizers behave in different ways towards light. E.g. powder stabilized with amyl alcohol proved to be more resistant to sunlight than that containing diphenylamine. The latter darkens very rapidly under the influence of light, which no doubt accelerates the decomposition of diphenylamine. 

The solution gradually darkens as the reaction proceeds stirring should be continued for at least 2 h as triflic acid is only sparingly soluble in hexane. The solvent is removed under reduced pressure and the grey solid residue is transferred to a sublimator. The colorless waxy product sublimes slowly between 40 and 70°C/10 3 torr onto a cold finger cooled to — 78°C with dry ice/acetone. Yield 0.648 g (91%). The reaction has been scaled up by a factor of 12 without diminution in yield. ... 

A generalization of the concepts of size factor and electronegativity has been made by Darken and Gurry [222] who plotted electronegativity... 

Cystoid macular edema, iritis, Herpes simplex keratitis, periocular skin darkening, and headaches have been described in patients treated with prostaglandin analogues. These adverse effects occur rarely, and cystoid macular edema, iritis and H. simplex keratitis occur in eyes with risk factors. Repeated rechallenge with masked controls is required to establish a causal relation. However, even without firm establishment of a causal relation, caution is advised with the use of prostaglandin analogues in the eyes of patients with risk factors for macular edema, iritis, and H. simplex keratitis (76). 

Aquatic plants and fish. Duckweed rapidly accumulated (r4C)-fenitrothion from the water column and maximum concentrations were observed after 5 to 10 days post-treatment in both years (Table III). The levels observed at 5 days represented concentration factors (BCFs) of 754 and 688 in shaded and unshaded exposures, respectively (Year 2), based on total radioactivity in water and plants. Concentrations in duckweed decreased to <10% of the maximum by 35 days each year. Levels of radioactivity in the plants were not significantly different in shaded and unshaded conditions. This differs from results of Weinberger et al (4) who observed 3-fold greater concentrations of ( 4C)-fenitrothion in Elodea densa in field microcosms under lighted compared to darkened conditions. Duckweed did not grow well under shaded conditions and by 17 days the density of the plant was about 10% of that in the unshaded pond. 

Several of the problems associated with the consumption of microbial cells are inherent to the cell and not intrinsic properties of the proteins per se. The presence of cell wall materials in unfractionsted cells is undesirable because it reduces the bioavailability of the proteins may contain antigenic, allergenic agents and factors causing nausea, gastrointestinal disturbances (flatulence diarrhea) and the cell wall materials also cause darkening of the cell material (50,51,52,53,54). 

Rathbun and Babb [20] suggested that Darkens equation could be improved by raising the thermodynamic correction factor PA to a power, n, less than unity. They looked at systems exhibiting negative deviations from Raoult s law and found n = 0.3. Furthermore, for polar-nonpolar mixtures, they found n = 0.6. In a separate study, Siddiqi and Lucas [22] followed those suggestions and found an average absolute error of 3.3 percent for nonpolar-nonpolar mixtures, 11.0 percent for polar-nonpolar mixtures, and 14.6 percent for polar-polar mixtures. Siddiqi, Krahn, and Lucas (ibid.) examined a few other mixtures and... 

In their initial work, the committee identified two other important factors from the works of Anton Hogstad of the St. Louis College of Pharmacy (22) and, Tapley and Giesy of E.R. Squibb Sons (23) which could influence their studies. Hogstad had studied the deterioration of cresol and noted that cresol kept in colorless, sealed tubes, did not darken when exposed to sunlight while those exposed in open tubes did. 

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