Differential crystallization

The kinetics of these reactions markedly favor sodium nitrite production. If some sodium nitrate is formed, it can be easily separated by differential crystallization. Otherwise, sodium nitrate can be formed by treating sodium nitrite with nitric acid ... 

Surface strengthening by differential crystallization. C Surface strengthening by Na+ <=> Li+ ion exchange. C Surface strengthening by 2 Li+ < > Mg2+ ion exchange. ... 

Fractional crystallization (or differential crystallization) is a process whereby two chemically compounds that form crystals with slightly different solubilities in some solvent (e.g., water) can be separated by a "tree-like" process. One should remember the herculean work by Marie Curie3, who by fractional crystallization isolated 0.1 g of intensely radioactive RaCl2 from 1 ton of pitchblende (a black mixture of many other salts, mainly oxides of uranium, lead, thorium, and rare earth elements). 

Crystal solubilization is facilitated by an alkaline pH of susceptible insects. The typical midgut pH is between pH 9-11 in lepidopteran larvae [37-39]. In mosquito larvae, the pH inside the posterior midgut/gastric caeca is between 7-8, while the pH inside the anterior midgut is close to 11 [40]. Thus alkaline buffers are usually used for in vitro solubilization of lepidopteran and dipteran active B. thuringiensis crystals. Differential crystal solubility can be useful in partial separation of toxins. For example, CrylA toxins are fully soluble at pH 9.5, while the Cry2 proteins require a pH of 12 for complete solubilization [41]. Moreover, pH has different effects on Cry toxin pore-formation activities [42], and differences in the level of solubilization can contribute to toxicity differences... 

This model (see Fig. 2.2) starts with any magma of changing composition and of different sources. Changes in chemical and physical properties take place. Moving occurs sometimes to higher levels of the earth crust, and consequently temperature as well as pressure gradually drop and differential crystallization starts. The first crystallization step... 

Analysis method based on the differential crystallization temperature of the compounds in the sample. This method is frequently used for the fractionation of lubricating oil into fractions by crude oil chemists. 

Stereoselective Resolution by differential crystallization of diastereomeric tartrate salts Resolution by differential crystallization of N-boc protected diester product... 

Fig.l Cumulative and differential crystallization analysis fractionation (Crystaf) profiles of a blend of two polyolefins... 

As pointed out in Section 7.3.1, SANS studies of deuterium-labeled polymers were initially based on the assumption [8] that the molecular configurations and interactions are independent of deuteration, or alternatively that the Flory-Huggins interaction parameter for labeled and unlabeled segments of the same species, /hd. is zero. However, it was subsequently discovered that isotopic substitution can influence polymer thermodynamics, in that deuterated and protonated polyethylenes exhibit melting temperatures differing by 6 °C, so their mixtures can segregate in the solid state (see Section 7.5.2), due to differential-crystallization effects [103]. Also, the... 

Thus, such limitations together with the requirement of high resolution certainly lower the expectations linked to future differential crystal structures of modified reaction centers, in particular of those from Rb. sphaeroides, as long as the native structure is only resolved to Furthermore, the resolution of crystals from modified reaction centers might suffer from additional complications, such as an increase of structural or energetic inhomogeneity and stability problems, as previously encountered in e.g. borohydride treated reaction centers from Rb. sphaeroides (Allen et al., private communication). 

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