Beckman, firm

The discussion of Section 5-1 clearly illustrates that the most important response characteristic of an ISE is selectivity. Depending on the nature of the membrane material used to impart the desired selectivity, ISEs can be divided into three groups glass, liquid, or sohd electrodes. More than two dozen ISEs are commercially available and are widely used (although many more have been reported in the literature). Such electrodes are produced by firms such as Orion Research, Radiometer, Coming Glass, Beckman, Hitachi, or Sensorex. 

The surface trough was made of Lucite, 45 X 15 X 1.5 cm. and was divided into two compartments of equal size by a septum of Lucite, 1.5 cm. high. Cooling channels for temperature control were milled into the bottom of the trough. The monolayer was spread inside a paraffined mica frame which floated on the water and was firmly positioned by external mounts. The surface tension was measured with a double-hook torsion balance and a sand-blasted platinum Wilhemy plate. A Beckman model G pH meter with standard glass and KC1 electrodes was used to measure pH. 

In contrast is the hugely successful American firm of Beckman Instruments, which constructed and marketed pH meters from 1935 and the DU Spectrophotometer from 1941. Papers of a biographical nature based on interviews with Arnold Beckman have been published.104,105 The development of nuclear magnetic resonance spectrometers by the firm of Varian is considered in another paper, with emphasis on the introduction of the Varian A-60, the first commercial instrument intended for the broadly trained chemist as opposed to the custom-built tools for the research specialist.106... 

Ref 34 and pamphlets which can be obtained from the firm). An apparatus developed during WWII by the National Research Council of Canada under the name of Ottawa Chronograph was also used in US. Its description is given in Ref 30a, pp 28-34 In addn to Potter Co, the following US firms are engaged in manuf of counter chronographs a) Berkeley Division of Beckman Instruments, Inc, Richmond, Calif b) Hewlett-Packard Co, Palo Alto, Calif c) Computer Measurements Co, San Fernando, Calif d) The Detectron Corp, North Hollywood, Calif and e) Lavoie Laboratories, Inc, Motganville, NJ There are probably other firms, but we have no info on their products... 

Because of the high resistance of the glass membrane (10 to 100 MO), it is not practical to measure the emf directly. Instead, pH meters either use a direct-reading electronic voltmeter or electronically amplify the small current that flows through the cell and detect the voltage drop across a standard resistor potentiometrically. Both battery-operated and ac line-operated pH meters are available connnercially from such firms as Beckman Coulter, Thermo Orion, and Coming. Such pH meters are calibrated to read directly in pH units, have internal compensation for the temperature coefficient of emf, and have provision for scale adjustments. 

Laboratory oxygen analyzers are produced by several firms, e.g., Beckman [55] and Radiometer [56]. 

Centrifuge the harvested material to obtain a firm pellet of bacterial cells (Example 3,000 xg for lOmin at4°C in Beckman Coulter Allegra 25R centrifuge.). 

Beckman Bibliography of Infrared Applications, Several issues of a bibliography of infrared applications compiled by W. F. Ulrich of Beckman Instruments, Inc., Fullerton, California, are available from that firm. The practical aspects of infrared spectroscopy are emphasized and the service is by no means a complete abstract of the literature. 

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