Aging study solutions

The form of aluminum in acid aqueous media was studied by preparing a series of solutions containing the same total concentration of aluminum, but with varying amounts of added base and determining the composition and pH of the solutions after various periods of aging. For convenience, these solutions will be designated aging study solutions. Electron microscopy was used to help determine the nature of colloidal-size material that formed in some of the solutions. 

Figure 2. Aluminum recovered as a function of analysis time for selected aging study solutions plus several standards...

Thus, the electron micrographs show conclusively that colloidal material is formed in the aging study solutions. Further, this material appears to be microcrystalline gibbsite. 

Dousma, J. de Bruyn, P.L. (1978) Hydrolysis-precipitation studies of iron solutions. II. Aging studies and the model for precipitation from Fe(III) nitrate solutions. J. Colloid Interface Sci. 64 154-170... 

A mixture of benzene and methanol (19 to 1) was used for spreading the alkyl phosphonates. To minimize the influence of benzene on the film properties, the concentrations of the spreading solutions were > 1.5 X 10 3 gram per ml., and the experiments were performed at tt > 4 dynes per cm. (25). Moreover, higher proportions of methanol in the spreading solution did not alter the film properties under study for selected monolayers. For the sulfates, a mixed solvent containing water-benzene-2-propanol (1 10 10) was used because with the benzene-methanol solutions the properties of the films depended on the age of solution from which the films were prepared. Stearic and palmitic acids were spread from either hexane or the benzene-methanol solvent used for the phosphonates. Identical desorption results were obtained with the two solvents. 

A different compatibility problem arises when ADN is mixed with KNO3. Aging studies show a drastic decrease in melting point. The reason is probably formation of eutectic solutions between the salts. This has also been observed in aging studies of GDN and KNO3 but not when GDN is replaced by guanylurea dinitramide (GUDN). 

Clinitest (Bayer Corporation, UK) was used to verify that the ferment had gone to completion. The ferments were centrifuged and the wine decanted from the lees. A sample (20mL) of each wine was stored in the dark at room temperature for aging studies. The lees (approx. 5mL) were extracted with 2xl0mL methanol/formic acid (90 10) with agitation. The methanol was removed by rotaiy evaporation, the remaining solution was made up to SmL with water and pH adjusted to approx 3.5 with sodium hydroxide (29). Samples were analysed immediately after the completion of fermentation and then on a weekly basis by HPLC. The clarified wines were also monitored by UV-Vis spectrophotometry. 

In the last decade the chemistry of aluminium salts hydrolysis related to the application of the products of their partial hydrolysis in coagulation has been studied in detail [5]. It has been found that as well as the pH value, temperature, precipitate ageing and solution, the composition of the hydrolysis product also depends on the initial ratio of the concentration of OH ions and aluminium, as well as on the rate of the base addition. The hydrolysis of aluminium salts influences a number of side reactions depending on the overall composition of water, since aluminium forms complexes with other ligands, such as sulphate, phosphate and fluoride. 

The mechanical properties of solution annealed SS 316 LN were studied after ageing at 1123 K for 10 h. Initially both strength and ductility increased and this could be attributed to the formation of Cr-N clusters. On further ageing, while strength increased, ductility decreased because of intragranular chromium nitride precipitation. SCC resistance is increased twice by ageing the solution annealed type SS 316 LN at 1123 K for 500 h. The increase in SCC resistance was marginal thereafter. 

Polymer Solutions Solutions were made up to approximately 0.2 wt% with deionized, distilled water, or NaCI containing aqueous brine as indicated. Oxygen was not excluded since similar PAM hydrolysis characteristics were observed in previous aerobic vs. anaerobic aging studies. 

Multivariate data analyses are sensitive not only to differences in the investigated gronps (snch as tumor versus non-tumor in this study) but also to changes in the measurement conditions. Such changes can result from, e.g., aging matrix solution and variations in instrument performance. It is not possible to consider all of these influences... 

Akinyele, B. and Odiyi, A. 2007. Comparative study of the vegetative morphology and the existing taxonomie status of Aloe vera L. Journal of Plant Sciences, 2 (5), pp. 558—563. Anand, P., Sundaram, C., Jhurani, S., Kunnumakkara, A. and Aggarwal, B. 2008. Ciu ciunin and caneer An old-age disease with an age-old solution. Cancer Letters, 267(1), pp.133-164. 

Figure 2. 29si NMR spectra of (a) the fresh stock solution and (b) the aged stock solution. Peak assignments are from reference (9). The squares represent the Si atom under consideration and circles represent all other Si atoms in the molecule. Alkoxy groups are implied where not shown to make the Si 4-coordinate, and oxygen atoms are assumed between all Si atoms. High resolution studies indicate that the -89 ppm peak is attributable to over 75% unhydrolyzed dimer.

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