Salt samples

One problem with the analysis of salt samples is their tendency to clog the aspirator and burner assembly. What effect would this have on the analysis ... 

Fig. 3. SEM photograph (a) and XRD patterns (b) of iron oxide powders in the spent salt sample...

Rust samples scraped off from exposed AISI 1019 steel surfaces were ground to fine size in a morter with a pestle. A fraction of the samples was subjected to a salts extraction process using distilled water to determine the concentration of most common ions by chemical analysis and to study changes in adsorption isotherm after elimination of hygroscopic salts. Samples were obtained from AISI 1019 steel coupons, exposed for up to six months at coastal and rural locations. 

In order to trace the migration of basalt-derived REE in the salt, REE distribution patterns (Fig. 7) and Nd isotopic compositions (Fig. 8) have been determined in a salt horizon adjacent to a basalt dyke (Fig. 2). The flat REE distribution patterns and the almost basaltic Nd isotopic composition of the salt samples collected at the basalt-salt contact point to a basaltic origin of the REE for this sample. With increasing distance from the contact, the patterns are more and more depleted in Ce, Pr, Nd, Sm, and Eu and the Nd isotopic compositions are slightly shifted towards lower eNd values, which, however, still remain above values typical for continental crust or Permian seawater (Stille et al. 1996, and citations therein). This evolution of the REE distribution patterns and the Nd isotopic compositions could basically be due to mixing between a basalt and a salt end member or, alternatively, it could have been fractionation of the REE during migration in the salt that modified the REE patterns. 

Fig. 7. Basalt normalized REE distributions of the salt samples R 4250 to R 4254 from 0.1 to 4.7 m from the basalt contact. The solid lines show the measured REE distributions. Note the depletion of Ce, Pr. Sm, and Eu appearing with distance. The dashed lines are calculated mixing patterns discussed in the text. See Fig. 2 for sample locations.

Fio. 22. Resolution of complex II with respect to succinate dehydrogenase by various chaotropes. Complex II was suspended in 50 mM Tris-HCl, pH 8.0. After addition of 0.6 M chaotrope the concentration of complex II was 8 mg/ml. After addition of the salts, samples were taken at the intervals indicated and assayed for succinate-Qi and succinate-PMS reductase activities. Solid lines, sucdnate-ubiquinone-2(Q) reductase activity dotted line, succinate-PMS reductase activity. Resolution temperature, 0° assay temperature, 38°. The complex II preparations used in the experiments of this and subsequent Figs. 24 and 25 had specific activities between 40 and 45 moles Qj reduced by succinate per min per mg protein. From Davis and Hatefi (169). 

Improvement in mass resolution by MALDI of samples loaded on synthetic membranes was particularly apparent in the MALDI of contaminated samples. We systematically examined the ability to remove measured amounts of contaminants from peptide and protein samples by doping previously pure samples with glycerol and salts. Samples doped with 5 % glycerol and 500 mM sodium were prepared for MALDI-MS analysis using the method described above. 

Intensive properties don t depend on the amount of the substance (sample size) present, whereas extensive properties do.]—The extensive properties of a substance will change with the size of the sample. For example, the color (intensive property) of table salt is the same, regardless of how much of it you have. The weight (extensive property) of your salt sample will certainly depend upon the size of your sample. (The wording of your answer may vary from mine.)... 

The influence of absorption by the quartz cell was examined by measurements of blank cells and some molten salt samples. In the blank test, the displacement of the absorption baseline was not observed. The lowest energy, which could be used in this system, was estimated to be lOkeV. Thereby, the XAFS spectra of some molten halides could be successfully obtained. The results showed that a small difference was observed among their results. It was concluded that the developed device is also suitable for the XAFS measurement of hygroscopic molten salts. 

Because the effect of neutralization by monovalent cations on the mechanical relaxations presents interesting features, it is also of interest to explore the effect of divalent cations. A preliminary study of this kind was conducted by Kyu and coworkers (58). Nafion acid of 1155 EW was neutralized with an appropriate BaCl2 solution to prepare a Ba-salt sample. The torsion pendulum results in the form of G, G" and tan 6 versus temperature are depicted in Figure 32. A peak is evident at approximately -90°C in the tan 6 and G" curves. Judging from the peak temperature, this y relaxation is probably caused by the same mechanism as in the acid and the monovalent salt samples described before. The 6 peak occurs at approximately -2O C and thus overlaps slightly with the y peak. The observation of the 6 region at such a low temperature may be due to the presence of residual water which would reduce ionic interactions within the ionic domains and in turn would enhance backbone mobility. 

Figure 10.8. CE analysis of other high salt samples. Sample was in 0.5 M sodium sulfate, 1.5 M sodium sulfate was added to the electrolyte. Peaks 1 = Br (10 ppm) 2 = NO3 (2 ppm). From Ref. [6]. with permission.

CE of anions in solutions of high salt content has a number of practical applications. Bromide and nitrate in seawater were detected without any pretreatment or dilution of the samples. Anions in other high-salt samples can also be analyzed directly. Figure 10.8 shows peaks for 10 ppm bromide and 2 ppm nitrate in 0.50 M sodium sulfate. The BGE contained 1.5 pure sodium sulfate. It was also possible to determine both bromide and nitrate in 0.5 M sodium perchlorate by using 1.5 M sodium perchlorate in the BGE. With 1.5 M sodium chloride in the BGE, perchlorate and nitrate coeluted and only bromide could be measured. 

Samples may be stored at 4°C for up to 1 yr without any loss in activity, although this may depend on the particular protein. Do not freeze the purified protein since this causes aggregation. NaCl and imidazole appear to prevent precipitation thus, it is important that the final product is stored at 4°C in the presence of one of these salts. Samples should not be kept in the absence of these salts for any longer than necessary. 

Problem If one hammers on a sample of metal (lead or copper), the metal can be flattered to lead or copper leaf metals with the cubic closed structure are very ductile (see E5.4). If, on the other hand, one hammers on a rock salt sample, the crystal splits into tiny pieces or breaks apart, forming crystal plates. These properties can be explained through the structure the layers of ions in a crystal are moved when force is used similarly charged ions stand at opposite sides and are responsible for the repulsive effect of the crystal layers (see Fig. 5.14). 

Material Hammer, tile as a trivet, knife copper or lead sample, rock salt sample. 

Under-water stress relaxation of the Nafion acid and Nafion-Na samples with an equivalent weight of 1200 was carried out by Kyu and Eisenberg (40). The degree of neutralization of the Nafion-Na was measured to be ca. 80%. Time-temperature superposed master curves of the two systems, reduced to a reference temperature of 50°C, are shown in Figure 6. The under-water stress relaxation behavior of Nafion acid resembles that of Nafion-Na, except for the fact that the elastic modulus is somewhat lower in the acid. This latter feature may be due to the difference in the degree of water absorption of the acid and salt samples (26,31). The swelling of Nafion acid is greater than that of Nafion-Na, which yields a material of lower modulus. 

Effect of Crystallinity. While neutralization is known to exert a strong influence on mechanical relaxations, it is conceivable that the degree of crystallinity is also significant. To explore this aspect, an amorphous Nafion salt sample was prepared by rapid quenching from the melt (40). The original Nafion salt (EW = 1200) had a degree of crystallinity of ca. 7% as revealed by a wide angle X-ray diffraction study (40). The quenched sample was also found to be completely amorphous by the absence of the crystalline diffraction peak. 

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