Polychromator method

The colour reaction is transient but it can be fixed with special reagents and applied for detection and identification of individual amino acids, by making use of polychromic methods, especially after a chromatographic separation i ... 

The molecular structure of the anchored Cr(VI) has been a strong point of discussion in the literature, and several molecular structures (monochromate, dichromate, polychromates) have been proposed (see Scheme 3). The nature of the silica support, the chromium loading, and the activation method can all influence the chemical state of the supported chromium. 

Chromium zeolites are recognised to possess, at least at the laboratory scale, notable catalytic properties like in ethylene polymerization, oxidation of hydrocarbons, cracking of cumene, disproportionation of n-heptane, and thermolysis of H20 [ 1 ]. Several factors may have an effect on the catalytic activity of the chromium catalysts, such as the oxidation state, the structure (amorphous or crystalline, mono/di-chromate or polychromates, oxides, etc.) and the interaction of the chromium species with the support which depends essentially on the catalysts preparation method. They are ruled principally by several parameters such as the metal loading, the support characteristics, and the nature of the post-treatment (calcination, reduction, etc.). The nature of metal precursor is a parameter which can affect the predominance of chromium species in zeolite. In the case of solid-state exchange, the exchange process initially takes place at the solid- solid interface between the precursor salt and zeolite grains, and the success of the exchange depends on the type of interactions developed [2]. The aim of this work is to study the effect of the chromium precursor on the physicochemical properties of chromium loaded ZSM-5 catalysts and their catalytic performance in ethylene ammoxidation to acetonitrile. 

Gosser, D. C., Ohnersorgen, M.A., Simon, A.W., and Mayer, J. W. (1998). PIXE analysis of Salado polychrome ceramics of the American Southwest. Nuclear Instruments and Methods in Physics Research B 136-138 880-887. 

At a high enough temperature, any element can be characterised and quantified because it will begin to emit. Elemental analysis from atomic emission spectra is thus a versatile analytical method when high temperatures can be obtained by sparks, electrical arcs or inert-gas plasmas. The optical emission obtained from samples (solute plus matrix) is very complex. It contains spectral lines often accompanied by a continuum spectrum. Optical emission spectrophotometers contain three principal components the device responsible for bringing the sample to a sufficient temperature the optics including a mono- or polychromator that constitute the heart of these instruments and a microcomputer that controls the instrument. The most striking feature of these instruments is their optical bench, which differentiates them from flame emission spectrophotometers which are more limited in performance. Because of their price, these instruments constitute a major investment for any analytical laboratory. 

Here is an extremely sensitive method for measuring nitrite (NOj) down to 1 nM in natural waters. The water sample is treated with sulfanilamide and N-( 1 -naphthylethylenediamine) in acid solution to produce a colored product with a molar absorptivity of 4.5 X ItHM" 1 cm- 1 at 540 nm. The colored solution is pumped into a 4.5-meter-long, coiled Teflon tube whose fluorocarbon wall has a refractive index of 1.29. The aqueous solution inside the tube has a refractive index near 1.33. The colored solution is pumped through the coiled tube. An optical fiber delivers white light into one end of the tube, and an optical fiber at the other end leads to a polychromator and detector. 

A line-scan of the illumination laser light has been used to enhance the scan rate, at least compared to the point-by-point scan [18, 21-25]. It remains compatible with a spectral acquisition of high resolution, since total fluorescence from the linear region can be projected onto the slit of an imaging polychromator. A CCD camera at the exit port records the fluorescence intensity as a function of the spatial coordinate and the wavelength in the two-dimensional sensitive area of the camera. This method... 

A few reports have appeared on combining the streak camera temporal dispersion with polychromators and three dimensional optical multichannel detection. This approach yields three dimensional fluorescence data for each laser pulse. With the present technological limitations of three dimensional detectors and streak cameras, however, data of this type suffer from low wavelength resolution. As detector and streak camera technology improve, this technique may become the method of choice for time and wavelength resolved emission spectra. 

For classification in routine lymphocyte subset analysis, expert analysis is often fully adequate. For polychromic flow cytometry, particularly when both lineage and functional phenotypes are being evaluated, more sophisticated analysis may be required. Indeed, more sophisticated analysis can define subpopulations that cannot be discriminated by any combination of two-dimensional projections of multicolor data (Zamir et al., 2005). One of the first steps in enabling more sophisticated downstream analysis is ensuring acquisition of robust data. Some of the recently described analytical methods for high-dimensional flow cytometry data are listed in Table 4.2-1. 

Aleinikov et al. [99] proposed a method for determining sulphur, selenium and tellurium in various samples by first obtaining volatile fluorides and then analysing them by GC. The sample was fluorinated with xenon difluoride in a reactor under static conditions at 150°C. After the reaction the volatile products were blown into a poly-fluoroethylene chromatographic column filled with 20% of Kel-F on Polychrome-1 and analysed at — 78°C. 

Michalski, S. (2008). A physical model of the consolidation process, particularly of paintings. In The care of painted surfaces materials and methods for consolidation, and scientific methods to evaluate their effectiveness, third international congress on Color and Conservation, Materials and Methods of Restoration of Movable Polychrome, Milan, lO-II November 2006 Works Proceedings (pp. 21-41). II Prato. 

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