Sacrificing agent

As stated earlier, an extensive laboratory review of many available commercial water-soluble polymers and selected experimental water-soluble polymers was conducted. A summary of the results is given in Table I. As shown, only polyvinylpyrrolidone survived the 121 (250 ) test in synthetic seawater more than a few days. Polyvinylpyrrolidone is not however an efficent viscosifier. Combined with its high adsorption characteristics in reservoir rock (polyvinylpyrrolidone has been used in selected cases as a sacrifical agent) and high price, polyvinylpyrrolidone is regarded as unsuitable for use in EOR. 

Many sweet-tasting foods and beverages, however, do not require the functionality of sucrose and sweet carbohydrates. These products are the typical fields of application of intense sweeteners. As bulk sweeteners are used for taste reasons rather than functionality these products offer possibilities to reduce calories without sacrificing any important product characteristic. Intense sweeteners are used as the sole sweetening agents in beverages, table-top sweeteners like powder or tablets, desserts and dairy products besides a variety of further areas of lesser importance. 

Corey originally used borane-THF as a stoichiometric reducing agent [2, 5]. The use of more robust borane sources, borane-N,N-diethylaniline [6, 7] and borane-N-ethyl-N-isopropylaniline [8, 9], rendered the CBS reduction easier to handle without sacrificing enantioselectivity. Borane-THF prepared in situ from NaBH4 and (CHalaSiCl in THF [10] was also shown to be useful for this type of reduction [11]. 

The basic ocular irritation test in the rabbit will be described in detail in another section, but it is important to point out that the number of test animals can be reduced from the usual six at each exposure level to two or, at most, three animals per dose without sacrificing much accuracy. Many test series have shown 88-91% accuracy with two animals per treatment group. The agent, instilled in the pouch formed by the lower eyelid, is held in place for 1 s and then released. The treated eye is not washed, allowing the animal s own tear secretions to flush out the material. The untreated eye serves as a control. Both eyes are examined at 1, 24, 48, and 72 h after treatment, the irritation (or damage) to the cornea, the conjunctiva, and the iris being scored numerically in a subjective manner. The test is open in that the experiment can be terminated at 72 h if there is no evidence of irritation, but observed effects can be assessed for a longer time period. 

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