Instantaneous separation

In an ensemble of flexible polymer chains, the instantaneous separation of two segments i and j varies from one molecule to another. Ensemble averages such as required in Eq. 2 are obtained by specifying W(r-jj), the probability that segments i and j are separated by ry. In an elastomeric rubber which is not so highly swollen that excluded volume interactions become important, and which is not too greatly deformed, W(r- j) takes a particularly simple form... 

Reaction of the appropriate alkene with 1 equiv of tellurium tetrachloride in chloroform or acetonitrile gives a 2-chloroalkyltellurium trichloride adduct in a high yield (see Section 3.5.1.2). Reduction of this adduct with aqueous sodium sulphide results in the instantaneous separation of elemental tellurium and formation of the starting alkenes which, in most cases, exhibit an inverted configuration (with relevant variations depending on the solvent and olefin used). The proposed mechanism involves an intermediate epitelluride. 

Slug flow Rapid extraction due to internal circulation flow, instantaneous separation of immiscible phase after extraction Limited operating conditions to form slug flow... 

Relation of Mean Nuclear Positions to rg.—rg is the value of the instantaneous separation of a pair of atoms, averaged over a Boltzmann distribution of all possible energy levels of the molecular vibrations. In terms of the axis system used for the discussion of rz, the instantaneous separation is given by the relation... 

It is emphasised that experimental details must be adhered to. Ether extraction of fats cannot be used and the amount of hydrochloric acid must be small to avoid a high chloride content at the time of precipitation. Chambers avoids emulsions in removal of fatty matter by extracting the hot aqueous solution with hot chloroform and then cooling instantaneous separation is obtained. 

Spiked, unspiked (blank) and control samples were extracted using the same protocol. Extraction from 95 % ethanol was best achieved by adding hexane in proportions of 1 1 with respect to the volume of simulant and 10% distilled water to provoke the instantaneous separation of the aqueous ethanol/hexane layers. Extraction from 15% ethanol or 3 % acetic acid was also performed with hexane as previously described. The extraction from olive oil was performed by adding a volume of acetonitrile equal to that of the simulant. After addition of the solvent, the mixtures were shaken manually for 1 minute and subsequently sonicated for 15 minutes. They were then left to separate (approximately 1 hour). Aliquots of the organic phase were taken and transferred into small labelled GC vials for analysis. Samples exposed in isooctane were analysed directly. 

The instantaneous separation distance is determined by measuring the intensity of evanescent light scattered by the object. The intensity of the light flickers with time as the distance between the object and the lower microscope slide changes due to Brownian motion. Because of the nonuniform illumination of the liquid by the evanescent wave, the amount of light scattered by the object is a measure of its proximity to the interface. Let us measure the intensity change while the distance to the slide is varied. Then the intensity as... 

At the column outlet, the purified products are instantaneously separated from the supercritical eluent by depressurizing it (the gas phase has no solvent power) while, in HPLC, the products are recovered diluted in the liquid eluent. 

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