Photoelectric index

Methods are described for determining the extent to which original natural color is preserved in processing and subsequent storage of foods. Color differences may be evaluated indirectly in terms of some physical characteristic of the sample or extracted fraction thereof that is largely responsible for the color characteristics. For evaluation more directly in terms of what the observer actually sees, color differences are measured by reflectance spectrophotometry and photoelectric colorimetry and expressed as differences in psychophysical indexes such as luminous reflectance and chromaticity. The reflectance spectro-photometric method provides time-constant records in research investigation on foods, while photoelectric colorimeters and reflectometers may prove useful in industrial color applications. Psychophysical notation may be converted by standard methods to the colorimetrically more descriptive terms of Munsell hue, value, and chroma. Here color charts are useful for a direct evaluation of results. 

Photoelectric-Colorimetric Method. Although the recording spectrophotometer is, for food work at least, a research tool, another instrument, the Hunter multipurpose reflectometer (4), is available and may prove to be applicable to industrial quality control. (The newer Hunter color and color difference meter which eliminates considerable calculation will probably be even more directly applicable. Another make of reflection meter has recently been made available commercially that uses filters similar to those developed by Hunter and can be used to obtain a similar type of data.) This instrument is not a spectrophotometer, for it does not primarily measure the variation of any property of samples with respect to wave length, but certain colorimetric indexes are calculated from separate readings with amber, blue, and green filters, designated A, B, and G, respectively. The most useful indexes in food color work obtainable with this type of instrument have been G, which gives a... 

Measurement yields both the differences between the outer potentials and the work functions (real potentials). If two phases oc an / with a common species (index i) come into contact, at equilibrium /, (< ) = (/ ), that is at(a) - <, (/ ) = ZiFApty. These quantities are mostly measured using the vibrating condenser, thermoionic, calorimetric, and photoelectric methods. 

Coleman, W. F. "Photoelectric Effect," http //www.jce.divched.org/ JCEDLib/WebWare/collection/open/JCEWWOR006/index.html, (Accessed May 22, 2006). 

The sedimentation equilibrium experiment requires much smaller volumes of solution, about 0.15 ml. With six-hole rotors and multichannel centerpieces (41) it is potentially possible to do fifteen experiments at the same time. For situations where the photoelectric scanner can be used one might (depending on the extinct coefficients) be able to go to much lower concentrations. Dust is no problem since the centrifugal field causes it to go to the cell bottom. For conventional sedimentation equilibrium experiments, the analysis of mixed associations under nonideal conditions may be virtually impossible. Also, sedimentation equilibrium experiments take time, although methods are available to reduce this somewhat (42, 43). For certain situations the combination of optical systems available to the ultracentrifuge may allow for the most precise analysis of a mixed association. The Archibald experiment may suffer some loss in precision since one must extrapolate the data to the cell extremes (rm and r6) to obtain MW(M, which must then be extrapolated to zero time. Nevertheless, all three methods indicate that it is quite possible to study mixed associations. We have indicated some approaches that could be used to overcome problems of nonideality, unequal refractive index increments, and unequal partial specific volumes. 

The location of the beam, rather than its intensity, is determined by the angular deflection of the beam caused by the refractive index difference between the contents of the two cells. As the beam changes its position of focus on the photoelectric cell, the output changes and the resulting difference signal is electronically modified to provide a signal proportional to the concentration of solute in the sample cell. 

Two separate (and not necessarily related) readouts of the test are (a) flame spread along the surface of the specimen as a distance traveled by the boundary of a zone of flame over time and (b) smoke developed as a change in optical density (as a progress curve of light absorption percent) between the light source and the photoelectric cell mounted in the vent pipe. These data are used to calculate the respective FSI and SDI as described in the ASTM test procedure. The indexes are calculated as relative values to those of select grade oak (FSI arbitrarily set as 100) and inorganic reinforced cement board (FSI set as 0) surfaces under the specified conditions. 

For characterization of smoke formation, light absorbance measured by the photoelectric cell is plotted against time. The area under the curve for the specimen is divided by that for the red oak and then multiplied by 100 to obtain a numerical index for the performance of the material in comparison to that of the red oak, regarded arbitrarily as 100 (while the asbestos-cement board represents the zero point of this scale). 

Thallium is also used in low-temperature thermometers, photoelectric cells, dye pigments, and to produce various types of resistant cements. Because of the element s high refractive index it is utilized in the manufacturing of optical lenses and imitation jewelry. Thallium is included as a component of corrosion-resistant alloys, organic reaction catalysts, and fireworks. The incorporation of thallium halides into organic alkylhalides produces formation of new complexes that act as phosphors. This is the basis for using thallium in scintillation counters [Nal(Tl)]. 

Fluorinated poly(methacrylates) or poly(acrylates), rich in trifluoromethyl groups, exhibit superior performance of chemical inertness, excellent weatherability, low refractive index, lower dielectric constant, and special surface properties [14,61]. Poly(2,2,2-trifluoroethyl methacrylate), poly(MATRIF), is an important class of such materials. It has been extensively used in high performance coatings [17], photoelectric communications, and microelectronics [62]. Poly(MATRIF) is easily produced by free radical polymerization using bulk, solution, and emulsion polymerization methods [63]. Structural characterization of NMR of poly(MATRIF) prepared by radical and anionic polymerization has been studied. Syndiotactic structure was obtained by radical initiator in contrast to an isotactic structure achieved by anionic polymerization [64]. 

Optical and electrical properties of plasma deposited films, sometimes unique indeed, as well as the easy of their deposition, at low temperature and low cost, on inexpensive substrates of almost any size and shape, render these materials very attractive for optoelectronic applications. The possibility to tailor optical parameters, such as refractive index and extinction coefficient, and what is particularly important - the ability to adjust parameters of the electronic structure, such as transport p, optical gap, density of localized states, etc., recommend these plasma films as active photoelectric elements, e.g. for solar cells and water splitting cells. 

Photoelectric cross-section index in b/e (bams per electron) ... 

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