Counters general

Because of the focusing of the diffracted rays and the relatively large radius of the diffractometer circle, about 15 cm in commercial instruments, a diffractometer can resolve very closely spaced diffraction lines. Indicative of this is the fact that resolution of the Cu Kcl doublet can be obtained at 20 angles as low as about 40°. Such resolution can only be achieved with a correctly adjusted instrument, and it is necessary to so align the component parts that the following conditions are satisfied for all diffraction angles  

line source, specimen surface, and receiving-slit axis are all parallel, 

the specimen surface coincides with the diffractometer axis, and 

the line source and receiving slit both lie on the diffractometer circle. 

Without exception all electronic counters were developed by nuclear physicists for studies of radioactivity. They can detect not only x- and y-radiation, but also charged particles such as electrons and a-particles, and the design of the counter and associated circuits depends to some extent on what is to be detected. Here we are concerned only with counters for the detection of x-rays of the wavelengths commonly encountered in diffraction. 

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Counter, Scintillation—The combination of phosphor, photomultiplier tube, and associated circuits for counting light emissions produced in the phosphors by ionizing radiation. Scintillation counters generally are more sensitive than GM counters for gamma radiation. 

The activity concentration of radon and of the free and aerosol attached radon daughters i/ere measured simultaneously. During these measurements the aerosol particle concentration i/as registered by means of a condensation nuclei counter (General Electric). 

The major opportunity for our technology was to be in store-printed labels. The most expensive items in supermarkets are found in the meat and fish counters. Generally, meat is cut and packaged in the store, and a label must be printed then and there. The store-printed labels require a somewhat different code than the package-printed labels, as they reflect the price of the item. That, however, is not important here. 

The counter generally provides several counting decades whose output is available in BCD format. Normally, only the first (faster) decade, or decades directly associated with some types of preset control, are of the synchronous type. Frequently, ICs with two decades are used, but LSI circuits with four or six decades are already present in various instruments. 

While the Smoliichowski equation is necessary for a Markov process, in general it is not sufficient, but known counter-examples are always non-Gaiissian as well. 

All lation of Phenols. The approach used to synthesize commercially available alkylphenols is Friedel-Crafts alkylation. The specific procedure typically uses an alkene as the alkylating agent and an acid catalyst, generally a sulfonic acid. Alkene and catalyst interact to form a carbocation and counter ion (5) which interacts with phenol to form a 7T complex (6). This complex is held together by the overlap of the filled TT-orbital of the aromatic... 

Optical counters have been widely used to monitor cleanroom technology and particles in oil. Instmments manufactured by Royco Inc. (Menlo Park, California) are available for studying aerosols and particles in Hquids. The HIAC counter (HIAC Instmments, Monte Claire, California) is a widely used stream counter for particles in fluid. One of the more recently developed optical counters is available from Particle Sizing Systems (Santa Barbara, California). The configuration of one of the widely used counters, the Climet counter, is shown in Figure 16. A general review of photozone counters is available (3). 

The results of several studies were interpreted by the Poole-Erenkel mechanism of field-assisted release of electrons from traps in the bulk of the oxide. In other studies, the Schottky mechanism of electron flow controlled by a thermionic emission over a field-lowered barrier at the counter electrode oxide interface was used to explain the conduction process. Some results suggested a space charge-limited conduction mechanism operates. The general lack of agreement between the results of various studies has been summari2ed (57). 

General Safety Aspects. Whereas cyanides have become infamous as poisons in part because of the use in prison execution chambers, Na2i death camps, and in over-the-counter dmg tampering cases, there is worldwide safe production of nearly one million t annually. 

Product Recovery. Comparison of the electrochemical cell to a chemical reactor shows the electrochemical cell to have two general features that impact product recovery. CeU product is usuaUy Uquid, can be aqueous, and is likely to contain electrolyte. In addition, there is a second product from the counter electrode, even if this is only a gas. Electrolyte conservation and purity are usual requirements. Because product separation from the starting material may be difficult, use of reaction to completion is desirable ceUs would be mn batch or plug flow. The water balance over the whole flow sheet needs to be considered, especiaUy for divided ceUs where membranes transport a number of moles of water per Earaday. At the inception of a proposed electroorganic process, the product recovery and refining should be included in the evaluation to determine tme viabUity. Thus early ceU work needs to be carried out with the preferred electrolyte/solvent and conversion. The economic aspects of product recovery strategies have been discussed (89). Some process flow sheets are also available (61). 

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