Scanning optics characteristics

Fischer U Ch 1985 Optical characteristics of 0.1 pm circular apertures in a metal film as light sources for scanning ultramicroscopy J. Vac. Sc/. Technol. B 3 386... 

PAL activity is assayed spectrophotometricaUy based on the methods of Koukol and Conn (1961) and Kataoka et al. (1983) by measurement of the rate of formation of t-cinnamic acid as the increase in absorbance at 268 nm. The reaction mixture consists of 2 ml of the enzyme preparation and 1ml of 25 pm l-phenylalanine. In the reference mixture, the L-phenylalanine solution is replaced by distilled water. The mixture is incubated at 37 °C for 3h with shaking. The reaction is stopped by the addition of 0.1 ml of 6 N HCl. After 5 ml of peroxide-free ethyl ether is added, the mixture is shaken again vigorously for extraction of the acidified fraction and then centrifuged at 3000 g for 5 min. The ether phase is obtained with a pipette, and the ether is evaporated to dryness under reduced pressure. The residue is dissolved in 4 ml of 0.05 N NaOH and the absorbance of the solution at 268 nm in a 1-cm quartz cell is measured. The enzyme activity is expressed as micromoles of t-cinnamic acid formed per g FW or per mg protein in fresh tissue/h. The reaction product is scanned with a spectrophotometer for comparison of its optical characteristics with those of authentic t-cinnamic acid. The absorption spectrum of the reaction product was identical with that of authentic f-cinnamic acid (Fig. 3). 

Table S36. Main characteristics of near-field scanning optical microscopy...

Physical testing appHcations and methods for fibrous materials are reviewed in the Hterature (101—103) and are generally appHcable to polyester fibers. Microscopic analyses by optical or scanning electron microscopy are useful for evaluating fiber parameters including size, shape, uniformity, and surface characteristics. Computerized image analysis is often used to quantify and evaluate these parameters for quaUty control. 

The bulk type response curve depends also on surface roughness [4.34]. Reference materials must, therefore, be carefully investigated by angle-scan before use. Angle-scan characteristics of the sample, i.e. the fluorescence intensity recorded at more than one glancing angle near (j>, should not deviate from those of the reference. The measurement must be performed under similar optical conditions. 

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