Specimen Isolation

Citronellal which was originally termed citronellone, is one of the characteristic constituents of citronella oil, in which it occurs to a considerable extent. It can be prepared by shaking the essential oil with a hot solution of sodium bisulphite, and decomposing the resulting bisulphite compound by means of sodium carbonate and distilling the citronellal in a current of steam. Citronellal is optically active, and it is probable that the specimens isolated from natural sources are mixtures of the two optically active isomers, so that the actual theoretical rotation is not known with certainty. 

This aldehyde has been isolated from various Eucalyptus oils by Baker and Smith. It has a pleasant odour resembling that of cumic aldehyde, with which Schimmel Co. have considered it to be identical. This, however, is improbable, and Baker and Smith consider it to have the formula CjHjjO, which would make it to be a lower homologue of the terpenic aldehydes. Its physical characters, however, are somewhat doubtful, as specimens isolated from the oils of Eucalyptus hemiphloia and Eucalyptus salubris show. These are as follows —... 

Proof of Constitution.—Since the crystalline a- and 8-forms of 3,4,6-trimethyl-D-glucose, isolated by Sundberg and coworkers,28 were each obtained by hydrolysis of methyl 3,4,6-trimethyl-/3-D-glucopyrano-side,82,154 the proof of the constitution of this glucoside obviously played an important part in the characterization of the trimethylglucose itself. Unfortunately, there is no such crystalline reference compound to correlate the earliest samples of sirupy 3,4,6-trimethyl-D-glucose157,168 with the crystalline specimens isolated by Sundberg and coworkers. 

DNA specimens isolated from different tissues of the same species have the same base composition. 

Nesbitt, H.W., Metson, J.B., Bancroft, G.M. (1986) Quantitative major- and trace-element whole-rock analyses by secondary-ion mass spectrometry using the specimen isolation technique. Chem. Geol.,55,139-160. 

For the sake of consistency, a terminology has developed within the atmospheric corrosion testing community with respect to testing. The test facility itself is commonly referred to as a corrosion yard. Racks, commonly fabricated from pipe or wood, are installed to hold the fixtures for the individual test specimens. The latter are referred to as "frames," and can be fabricated from wood or metal (nickel-copper alloy, stainless steel, aluminum, etc.). These frames are usually designed to hold approximately 75 specimens, isolated from each other and the test frame by porcelain, plastic, or rubber insulators." Thus, a corrosion yard... 

Specimen Isolation (SI) A method used during the analysis of insulating samples... 

Two usehil measures of the performance of a sound-isolating constmction are sound transmission loss (TL) and noise reduction (AIR). Sound transmission loss is defined as follows, where IH is the incident sound power (Watts) on the source side of the specimen, and W is the transmitted sound power on the receiving side (7). 

Orotic acid (971) has a chequered history. It was isolated in 1905 from the whey of cows milk in Italy and it was subsequently synthesized in the United States in 1907. However, the workers involved were discouraged by some difference in melting points and no direct comparison of specimens was ever made. To make matters worse, the same laboratories prepared the isomeric 5-hydroxy-2-oxo-l,2-dihydropyrimidine-4-carboxylic acid and announced it as orotic acid, again without any direct comparison. Only in 1930 did a German worker actually compare directly natural and the original synthetic orotic acid, thereby showing them to be identical (30CB1000). 

In recent years researchers at West Virginia University have developed coal-derived pitches on a laboratory scale in quantities sufficient to make 1 kg samples of calcined coke for fashioning graphite test specimens. The pitches were derived by uhlizmg solvent extraction with N-methyl pyrrohdone (NMP). This solvent is able to isolate coal-based pitches m high yield and with low mineral matter content [13]. It is this work that will form the basis of the discussion for the later part of this chapter. 

The specimen examined by King - contained a mixture of alkaloids, which was partially separated by a special process into (a) non-quaternary bases, and (b) quaternary bases. From the former, which was a mixture of phenolic alkaloids, Boehm s protocuridine and a new isomeride of this, u oprotocuridine, were isolated. 

Santene has also been examined by Aschan. The following are the characters of the purest specimens which have been isolated from sandalwood and Siberian nine oils —... 

Baker and Smith have isolated from a number of eucalyptus oils, a sesquiterpene to which they have given the name aromadendrene. This compound was separated from the oil of eucalyptus nova-angelica in the dextrorotatory form, and from the oil of eucalyptus baUeyana in the laevorotatory form. The two specimens had the following characters —... 

A specimen from lime oil, however, has been isolated with an optical rotation - 20° 7, and a specimen of dextro-linalol from orange oil, with a rotation of + 19° 18. The characters of pure linalol, therefore, may be taken approximately as follows —... 

Baker and Smith have isolated an aldehyde from the oils of Eucalyptus hemiphloia and Eucalyptus bractata, of the formula C,oH,gO, which they have named cryptal. Two specimens prepared from the former oil had the following characters —... 

It is significant that most of the data from which a remarkable uniformity of attack is deduced are derived from small isolated panels. This is the most convenient form of specimen for measurements of corrosion rates by loss of weight but it eliminates the important effect of galvanic currents passing between remote parts of a large structure. It is believed that the experience of civil engineers and other users would not support the conclusion suggested by panel tests that corrosion is no faster in tropical than in temperate waters. 

Care should be taken to avoid short circuits for instance, an insulated specimen, being common with the ground point of some potentiostats, can become electrically reconnected to the autoclave if the latter is not separated from ground by using an isolation transformer. 

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