Vacuum historical development

Much of the pioneering research on nitrosoalkane dimers is based on reactions involving the formation of free radicals. Most of the reactions are of little value from the preparative standpoint, either because a highly specialized apparatus (e.g., photolysis equipment, high-vacuum trains, even a Van de Graaff generator) is used or because complex mixtures of products are produced. However, this work is of such importance in the historical development of aliphatic nitroso chemistry that it merits a brief review here rather than relegation to Section 5. 

Automation in the pipetting and transferring of solutions has been suggested for many years (see, for instance, Rowe (Rl), 1916). No attempt will be made here to cover the historical developments in this field. Any automatic pipet must supply the positive or negative pressure (with respect to atmospheric pressure) needed to move a liquid from the reservoir into the pipet. This has variously been supplied by such means as hydrostatic pressure, external vacuum or pressure pumps, in... 

For reasons of economy and also for reasons that are historically developed, primary vacuum pumps with inter casings have prevailed in the industry up to now. Deformations of the impeller and inter casing rotationally symmetrical to the shaft centre are conceivable for the enlargement of the working openings. Conical and cylindrical hubs are already completed constructions (Figure 3.7). The possibilities of the medium conveyance discussed in the earlier details as well as the design of the pressure ports are also transferable to the employment of these control bodies. 

For evaporation under coarse vacuum a variety of evaporator types is available. They represent a historical development, and each type has its specific field of application. Some typical evaporator types are described here. 

The filter deck of a vacuum drum filter consists - as already described - of a number of independent filter cells which we may be regarded - in historical development terms - as separate suction filters. 

D.M. Mattox, The historical development of controlled ion-assisted and plasma-assisted PVD processes, in Proceedings of the 40th Annual Technical Conference, Society of Vacuum Coaters, 1997, p. 109. 

TABLE I. Historical Development of Semiclassical Theories for the Metal/Vacuum... 

Historically, EELS is one of the oldest spectroscopic techniques based ancillary to the transmission electron microscope. In the early 1940s the principle of atomic level excitation for light element detection capability was demonstrated by using EELS to measure C, N, and O. Unfortunately, at that time the instruments were limited by detection capabilities (film) and extremely poor vacuum levels, which caused severe contamination of the specimens. Twenty-five years later the experimental technique was revived with the advent of modern instrumentation. The basis for quantification and its development as an analytical tool followed in the mid 1970s. Recent reviews can be found in the works by Joy, Maher and Silcox " Colliex and the excellent books by Raether and Egerton. ... 

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