Color rates

Photochromic silver—copper haUde films were produced by vacuum evaporation and deposition of a mixture of the components onto a sUicate glass substrate (13). The molar ratio of the components was approximately 9 1 (Ag Cu) and film thicknesses were in the range of 0.45—2.05 p.m. Coloration rate upon uv exposure was high but thermal fade rates were very slow when compared with standard silver haUde glass photochromic systems. 

Phenols, cresols, and quinolines are examples of compounds found in fuel which can degrade in color in the presence of light and air. If present in fuel, these compounds can readily degrade the ASTM color or Saybolt color rating of the fuel. These compounds are shown in TABLE 4-4. 

The coloration rate of 18a was determined to be 1.1 ps, while the decoloration rate of 19b was 2.1 ps. Both coloration/decoloration reactions take place in less than a few picoseconds in solution. 

The quantum yields and kinetics of the photobleaching of these compounds were determined, and their thermal coloration rates and activation energies were measured. The pH dependence of the spectral absorption changes, due to both the shift in the position of the protonation equilibrium between the spiro form and its salt, and the equilibrium between the salts of the spiro form and the open form, were also measured. A detailed analysis of the extensive data led to the spectroscopic identification of the short-lived ground-state cis conformers of the open forms of the five compounds studied. The photobleaching process is a photo trans-cis isomer-... 

The color, rate of fade, and intensity of 2.2-diphcnyl-5-alkoxycarbonyl-2//-naphtho [1,2- /)]py ran will be further affected by additional substituents on the molecule. As can be seen in Table 3.6, para methoxy(s) on the phenyls speeds the fade and bathochromically shifts the colored form. Electron-donating groups at the 6-position have a similar effect on the color but tend to slow the fade. The enhanced rate of fade brought about by the 5-carbomethoxy can be further promoted by a 6-propionyloxy (or related) group. 

Figure 14 Effect of film thickness and concentration of oxybenzone on coloration rate of sulfisomidine tablets, (o) Control (one point), ( ) 2%, ( ) 0.5%, (3) 5%, ( ) 1%, ( ) 10%. Source. From Ref. 17.

Cefoxitin is a broad spectrum, semi-synthetic cephamy-cin antibiotic. The free acid form is a white, crystalline, practically insoluble solid and therefore the decision was made to use the sodium salt to provide a sterile solution for intravenous administration. It was soon evident that the sodium salt of cefoxitin would have limited stability in solution and would not lend itself to the formulation of a marketable solution product. Stability studies highlighted the advantages of sterile crystalline solid over amorphous freeze-dried product, and also the need for rubber stopper screening studies to eliminate interactions between sodium cefoxitin powder and rubber, and finally the profound effect of oxygen on the coloration rate of the product. 

I. Horikoshi and S. Hata, Physicochemical studies on water contained in solid medicaments. VI. On the evaluating of the coloring rate of solid medicaments [in Japanese], Yakugaku Zasshi 86, 356-366 (1966). 

This could indicate, in particular, that the greater the concentration [Vci] in the initial material (i.e. the higher o i) the higher the rate of coloration The fact that the rate of coloration suddenly decreases as the temperature is lowered could support this point when the temperature is decreased, the material enters the extrinsic conductivity range where the concentration [Vq] ] rapidly decreases (compare diagram 1 and 5). This point has already been underlined by Tsikin and co-workers In the same way the chemical coloration rate was observed to sharply decrease in the extrinsic conductivity range. ... 

Al.1.2 The final result from this test method is a tube color rating based on an arbitrary scale established for this test method plus two additional yes/no criteria that indicate... 

If the deposit is peacock color, rate this as Code P, but also rate any deposit that shows normal deposit color on... 

This test method covers an instrumental method for the CIE (Commission International de I Eclairage) tristimuius measurement of the color of near-clear liquid samples. The measurement is converted to color ratings in the platinum-cobalt system. 

All samples were found to be water-sensitive (including atmospheric moisture) to a varying extent. ZeoUtes X and Y with CdS clusters in their pores immediately became deep yellow-orange upon immersion in water or any polar, non-basic solvent ZeoUte A loaded with CdS clusters, however, slowly developed a yellow-orange color over a longer period of about 1 h when immersed in water [301]. The different coloring rates point to different rates of aggregation or mobility of the CdS species. 

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