Correlation with sodium content

The increase in octane observed using dealuminated faujasite compared to high cell size rare earth exchanged faujasite has been correlated with the Si/AI ratio of the sieve and with the sodium content (3). While the relationship between Si/Al ratio as measured by unit cell is confirmed by pilot unit studies in our laboratory. Figure 1, the relationship with sodium content is more complicated. Figure 2. Sodium added to the catalyst after hydrothermal dealumination reduces activity but does not affect octane, while sodium present before hydrothermal dealumination increases activity but does reduce octane. This result implies that selectivity for octane is related to structures formed during... 

Na NMR spectroscopy permits a direct and non-invasive quantification of sodium ions in cheeses. A linear correlation was found between total sodium concentration as determined by SQ signals and chloride ion concentrations. As expected, relaxation times from SQ experiments were found to correlate with water content. The DQ experiments highli ted the presence of bound sodium ions, or sodium ions with restricted motion, in such food samples. The term bound for sodium ions in these samples could be considered an overstatement, as it is difficult to discriminate between restricted motion induced by the viscosity of the medium, and those induced by sodium binding to proteins. 

The other advantage of dealumination is improved coke selectivity. Vlhile coke selectivity correlates with unit cell size, the correlation is different than the one for octane, and there is no correlation between coke selectivity and sodium content 5). 

In a given facies, the sodium and titanium content of clinopyroxene shows a negative correlation with depletion (or chromium content) and can increase substantially in metasomatized xenoliths. The substimtion of sodium, chromium, and aluminum has a complex relationship with T, P and degree of depletion but in general, clinopyroxene from higher P samples contains more sodium. Representative analyses for different peridotite facies are shown in Table 4. 

Non-specific hydration, or hydration of the lattice without a first-order phase transition, also must be considered. Cox, Woodard, and McCrone reported the moisture uptake profile of cromolyn sodium, and the related effects on the physical properties of this substance. Although up to nine molecules of water per molecule of cromolyn sodium are sorbed into the crystalline lattice at 90 /o relative humidity, the sorption profile does not show any sharp plateaus corresponding to fixed hydrates. Rather, the uptake profile exhibits a gradual increase in moisture content as relative humidity increases, which results in marked changes in X-ray diffraction patterns, density, and other physical properties. For this example, moisture uptake onto cromolyn sodium was correlated with expansion of the lattice in the b crystallographic direction, which was shown to be reversible on dehydration. 

However, it appears that better correlation with gel times is obtained when the amounts of extractable and unextractable wood acids are considered separately (37). Although several procedures do exist in the literature for the determination of acid content in wood, many of these involve extraction of wood with various solvents, and they estimate the acid content in the extractives only. In contrast, we developed a procedure that acknowledges the presence of soluble as well as insoluble acids in wood. The method is based on the reaction of wood acids with aqueous sodium acetate to liberate an equivalent amount of acetic acid. Subsequent pH titration gives the total acid content. The soluble acids are determined by water extraction... 

Our estimates of the acid contents of heartwoods and sapwoods of red oak, hickory, southern pine, white fir, and Douglas-fir are given in Table I. The acid contents were correlated with the gel times of urea-formaldehyde resins (36) in contact with the same sample lots of the different species of wood. The correlations are presented in Table II. It is seen from Table II that the best correlation of gel times is obtained with insoluble acid content for each of the empirical fits that were tried. Similarly, the pH of the sodium acetate extracts showed better correlations with the gel times than the pH of the water extracts (37). 

TGA, there were two peaks in the derivative curve. It was concluded that these were due to the loss of free and lamellar water from the cream, and therefore TGA could be used as a QC tool. The lamellar structure of creams can also be confirmed using small angle X-ray measurements (Niemi and Laine 1991). For example, the lamellar spacings of sodium lauryl sulphate and ce-tostearyl alcohol liquid paraffin creams were found to increase in size (from 8.5 to 17.6 nm) as the water content of the cream increased until, at > 60 percent water, the lamellar structure broke down. This was correlated with earlier work that showed that at this point, the release of hydrocortisone was increased (Niemi et al. 1989). 

The possibility of alkali metal ion-binding can be dismissed on the basis of sodium and potassium ion studies [26,36,139—145]. Glass electrode studies on serum indicate a correlation with flame photometer sodium levels amounting to no sodium binding [2,143]. One premise for this is the assumption of serum water content being 96 per cent by volume giving a mean /nb of 0.747 com-... 

Nitrate may also be determined by LC with an anion-exchange column. A comparison has been made between the traditional method of nitrate determination using a reducing cadmium column and spectrophotometric determination with a reversed-phase LC method with orthophosphoric acid adjusted to pH 3.5 with sodium hydroxide as the mobile phase. A high correlation was observed between the nitrate content determined by the two methods. However, LC was found to be more precise, reproducible, and appropriate for routine work. 

Based on the ability of PSP toxins to block sodium channels, a reverse toxicological assay has been proposed using cultured cerebellar neurons in which protection by saxitoxins from neurodegeneration induced by the sodium channel activator veratridine is measured. PSP content is calculated by comparison with known concentrations of purified saxitoxin, and values obtained with this method show very good correlation with values from LC and mouse bioassay. 

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