Standing reserves

Compared to the above-mentioned simple methodical approaches to the measurement of VOCs and SVOCs in indoor air of automobiles, the approach of the Technischer Uberwachungs-Verein Nord (TUV Nord), Hamburg, is fundamentally different. In a test room, a stationary test stand reserved exclusively for this purpose was constructed where the air inside cars could be tested by following a uniform standardized programme every time (Bauhof and Frels, 1985). This test stand was used frequently for some time... 

All glassware must be scrupulously clean (see Section 3.8), and if it has been standing for any length of time, must be rinsed with distilled or de-ionised water before use. The outsides of vessels may be dried with a lint-free glass-cloth which is reserved exclusively for this purpose, and which is frequently laundered, but the cloth should not be used on the insides of the vessels. 

The separation and collection of the violet zone (Rj 0.98) of fraction 1 led to the isolation of m- and p-camphorene (compound 4 and compound 5) and cembrane A as well. Thongh m- and p-camphorene are taxonomic marker substances of the species B. serrata, it is pointless to use them in TLC, because the corresponding violet spot on the chromatogram of B. carterii stands for verticilla-4(20),7,l 1-triene, the taxonomic marker substance of B. carterii and cembrene A, too. These violet snbstances shonld be reserved for GC investigations. 

N. Conformational Analysis of Molecules in Solution (CAMSEQ). A problem of long standing in chemistry has been to estimate the relationship between the conformation of a molecule in the crystal, as measured by X-ray methods, with that in solution where barriers to rotation are greatly reduced. A sophisticated program set for Conformational Analysis of Molecules in Solution by Empirical and Quantum-mechanical methods (CAMSEQ) has been developed for this purpose by Hopfinger and co-workers [l2] at Case Western Reserve University. 

However, the possible general toxicity is only observed in the pregnant population and is therefore subject to the same reservations as mentioned above for the generation studies. Such studies cannot stand alone for an assessment of the repeated dose toxicity potential of a substance and thus cannot serve as the sole basis for the assessment of the repeated dose toxicity. 

Samples of 50 pi plasma, standard or control plasma, 20 pi internal standard and 10 pi dithiothreitol solution are thoroughly mixed (vortex) in 1-ml Eppendorf tubes. The tubes are left to stand at room temperature for 15 min. Samples are then depro-teinised by the addition of 500 pi deproteinising acetonitrile solution, with thorough vortex mixing followed by centrifugation at 14,000 rpm (11,000 x g) for 5 min (4°C). Tandem mass spectrometry analysis is performed on 200 pi of the supernatant reserved in appropriate vials. If the analysis is not performed immediately, samples can be stored at -20°C until analysis. 

When 4g of potassium hydrogen fluoride are dissolved in the clear brown liquid (reserved as directed) and the mixture is allowed to stand in ice overnight, crystals of red-brown potassium hexafluoromanganate (III) can be isolated from the solution by the method just outlined for the tetravalent complex fluoride. 

Tradition reserves the use of the name acid for substances that transfer protons measurably to water. Thus the carboxylic acids stand out from alkynes, halides, alcohols, and simple aldehydes and ketones in giving water solutions that are acidic to indicator papers or pH meters as the result of proton transfers from the carboxyl groups ... 

The cold reaction mixture is poured slowly with stirring into a 3-1. beaker containing 150 ml. of concentrated hydrochloric acid, 300 ml. of saturated aqueous sodium chloride, and 150 g. of ice. A white precipitate starts to separate (Note 8). An additional 150 ml. of saturated aqueous sodium chloride is added to the beaker and, after a minute, an upper layer begins to appear. The contents are transferred to a 2-1. separatory funnel and allowed to stand for 15 to 30 minutes while an upper brown layer separates. The upper layer is reserved while the lower layer is extracted with several portions of benzene totalling 900 ml. The upper layer and the benzene extracts are combined and washed seven times with 1-1. portions of water containing 10 ml. of concentrated hydrochloric acid. The benzene layer is then washed successively with 100-ml. portions of aqueous 2% sodium bicarbonate until the washings are basic. It is dried over 100 g. of anhydrous sodium sulfate, treated with 1 g. of charcoal, and filtered. The filtrate is concentrated at reduced pressure to give 59-62 g. (60-63%) of crude 3,5-dinitrobenzaldehyde, as a... 

Despite the need for cleaning new cooling systems, it is unfortunately common practice to ignore this step and move on to some form of passivation (prefilming). At its simplest, the method most usually undertaken is to merely increase the scale/corrosion inhibitor product reserve by a factor of 2 to 3x, for a period of up to a week, at low load and low cycles of concentration. This is seldom satisfactory as a stand-alone step, although it is normally a beneficial follow-up step in the cooling system passivation process. 

Except for a few isolated cases, the letters v, w, x, y, and z are reserved to denote elements in X. The letters p, q, r, s, t, and u will mostly stand for elements of S. (Clearly, the letter p will also often be used to denote prime... 

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