Design apparatus

Use of stroboscopic techniques and carefully designed apparatus can make this sort of method very accurate. 

To confirm the pertinence of a particular dispersion equation, it is necessary to use extremely precise and accurate data. Such data can only be obtained from carefully designed apparatus that provides minimum extra-column dispersion. In addition, it is necessary to employ columns that have intrinsically large peak volumes so that any residual extra-column dispersion that will contribute to the overall variance is not significant. Such conditions were employed by Katz et al. (E. D. Katz, K. L. Ogan and R. P. W. Scott, J. Chromatogr., 270(1983)51) to determine a large quantity of column dispersion data that overall had an accuracy of better than 3%. The data they obtained are as follows and can be used confidently to evaluate other dispersion equations should they appear in the literature. 

When designing apparatus with several materials, consider all materials as an integrated entity. More highly resistant materials should be selected for the critical components and for cases in which relatively high fabrication costs are anticipated. Often, a compromise must be made between mechanically advantageous properties and corrosion resistance. 

An unusually extensive battery of experimental techniques was brought to bear on these comparisons of enantiomers with their racemic mixtures and of diastereomers with each other. A very sensitive Langmuir trough was constructed for the project, with temperature control from 15 to 40°C. In addition to the familiar force/area isotherms, which were used to compare all systems, measurements of surface potentials, surface shear viscosities, and dynamic suface tensions (for hysteresis only) were made on several systems with specially designed apparatus. Several microscopic techniques, epi-fluorescence optical microscopy, scanning tunneling microscopy, and electron microscopy, were applied to films of stearoylserine methyl ester, the most extensively investigated surfactant. 

A description of the decompn of AN into product gases examination of the reactions of AN with Amm bicarbonate, Amm bichromate and Amm acetate and a study of burning laws using a specially designed apparatus)... 

We shall first describe the details of a newly designed apparatus that is critical for the accurate determination of the friction coefficient of gels. As shortly stated in the previous section, there are some difficulties to be solved for an accurate determination of the friction coefficient of gels. In the following, we will describe such difficulties in detail and the way they are solved. 

An elaborately-designed apparatus for carrying out an adaptation of this preparation has been devised by Shaw and Reid.4... 

Recent work (l, 2, 3) by the junior author and his colleagues on thermally cycled gas compression by adsorption/desorption of N20 and other gases in zeolites created a need for a theory derived from first principles. Such a theory would be capable of accounting for the detailed physical behavior over a wide range of pressures, and thereby establish a reliable formalism to predict behavior and design apparatus. More important, however, is the need for a unifying theory to support and accelerate further work on all aspects of zeolite research and their applications. 

The hexafluoroantimonate is chosen for this type of reaction because CsSbF6 is sparingly soluble in AHF (1.8 mg/g of HF at —78QC) and can be filtered off at the reaction temperature in a specially designed apparatus (61). The tetrafluoroammonium salt isolated by evaporating the filtrate can then be further purified by recrystallization from HF or BrF5. 

An obvious disadvantage of the method is that the reaction of one mole of a substance requires n x 96,500 coulombs, where n is the number of electrons in the electrode reaction. As high currents can be employed when properly designed apparatus and well-chosen conditions are used, however, this is not a serious disadvantage. Furthermore, the electron is a very inexpensive reagent. 

A preliminary study has also been made of the further reactions of the S2 intermediate by flash photolysis with kinetic mass spectrometry. About 0.2 torr of COS (H S or CS2) admixed with co. 15 torr He, were flashed in a suitably designed apparatus and the resulting gas mixtures analyzed at a particular m/e value by a fast response mass spectrometer displaying the concentration vs. delay time curve on an oscilloscope. All polymeric states between S2 and Sg were detected with the possible exception of S7, but no species higher than Sg were present. Representative ion intensity vs. delay time plots for Sg, S4, Sg, Sg, and Sg are shown in Figure 4. The S3 and Sg species could have arisen from the disproportionation reaction of S4. It is seen that S2 decays fast with the simultaneous formation of the higher molecular weight polymers. The rate of formation and decay of Sg is the slowest and its spectrum persists for many tens of seconds. 

H. A. Stuart, Zeitschr.f, Physik 51, 490 (1928). t For further vapour pressure measurements made at various temperatures and pressures by means of specially designed apparatus, see O. Steiger, Dissertation (Eidgenossische Technische Hochschule, Zurich). 

The preparation in this ease is carried out in a specially designed apparatus, the reaction vessel being made of steel, and the sodium... 

Temperatures of around 1000 K are the upper limit for conventional flash photolysis experiments, higher temperatures require specially designed apparatus or shock tubes. There have been three shock tube studies of reaction (32). Glanzer et al. [62] determined k22 at 1350 K, between 1 and 25 atm, initiated by the rapid thermal decomposition of azomethane with the methyl radical concentrations being monitored by UV absorption. Direct measurements of the absorption coefficient at 1400 K were used to determine absolute methyl radical concentrations. Similar measurements were performed by Hwang et al. [63]... 

In industry it is frequently worth while to work out a procedure and design apparatus that may be used in the synthesis of only one member of a chemical family. In the laboratory a chemist is seldom interested in preparing the same compound over and over again, and hence he makes use of methods that are applicable to many or all members of a particular family. 

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