Multiple techniques

For several years, the French Atomic Energy Commission (CEA) has developed modelling tools for ultrasonic NDT configurations. Implemented within the CIVA software for multiple technique NDT data acquisition and processing [1,2], these models are not only devoted to laboratory uses but also dedicated to ultrasonic operators without special training in simulation techniques. This approach has led us to develop approximate models carrying out the compromise between as accurate as possible quantitative predictions and simplicity, speed and intensive use in an industrial context. 

The number of experimental factors which influence the results increases considerably when thermogravimetry is combined with other techniques such as DTA, gas chromatography46, mass spectrometry, X-ray etc. A systematic discussion of all these additional factors would lead too far, therefore only a representative example will be discussed here. One of the often-applied multiple techniques is the combination TG-DTA. Besides the actual thermal reactions of the sample, the important factors in DTA are the heat capacity and the thermal conductivity of the sample. Optimum heat transfer is required for such thermoanalytical measurements therefore the shape of the sample and its contact with the crucible is of special importance. 

One method of partitioning the system equations is to compute the maximal loops using powers of the adjacency matrix as discussed in Section II. Certain modifications to the methods of Section II are needed in order to reduce the computation time. The first modification is to obtain the product of the matrices using Boolean unions of rows instead of the multiplication technique previously demonstrated to obtain a power of an adjacency matrix. To show how the Boolean union of rows can replace the standard matrix multiplication, consider the definition of Boolean matrix multiplication, Eq. (2), which can be expanded to... 

Multiple techniques are also possible such as TG-DTA whereby the mass loss of a sample and the DTA curve may be obtained simultaneously. 

The currently accepted spectroscopic assignments were obtained by a combination of multiple techniques. Leyva et applied matrix absorption and emission spectroscopy along with flash photolysis techniques. Chapman and LeRoux obtained the matrix IR spectrum of cyclic ketenimine K and Hayes and Sheridan obtained the matrix IR and UV-Vis spectrum of triplet phenylnitrene and cyclic ketenimine K. Schuster and co-workers applied time resolved IR and UV-Vis spectroscopy and demonstrated the formation of cyclic ketenimine K in solution, the species that absorbs strongly at 340 nm. 

The sample is embedded in an uncured polymer resin, cured, then polished to the point of optical smoothness. Specular reflectance issues may complicate the images. The technique can be used for depth profiling and offers an alternative for samples that are difficult to microtome. The technique produces samples that can be imaged with multiple techniques. 

As analytical capabilities improve, multiple procedures are linked together in series to effect analyses. Procedures combined in this manner are called hyphenated techniques. Ferrer and Furlong [124] combined multiple techniques—accelerated solvent extraction (ASE) followed by online SPE coupled to ion trap HPLC/MS/MS—to determine benzalkonium chlorides in sediment samples. Online SPE, especially coupled to HPLC, is being used more routinely. This approach allowed online cleanup of the ASE extract prior to introduction to the analytical column. 

K. M. Morrissey, R.J. O Connor and H.D. Dust, Multiple-technique analytical characterization of a mixture containing chemical-weapons simulant... 

M.D. Brickhouse, W.R. Creasy, B.R. Williams, K.M. Morrissey, R.J. O Connor and H.D. Durst, Multiple-technique analytical characterization of a mixture containing chemical-weapons simulant from a munition, J. Chromatogr., A, 883, 185-198 (2000). 

Using a computer and matrix multiplication techniques the first and second peptide units can be rotated through all possible combinations of values of phi and psi. For each possible set of these dihedral angles, the distances between all pairs of nonbonded atoms can be compared using a set of minimum interatomic contact distances (Table 2.3) if the distance between any set of atoms is smaller than the minimum contact distance then that conformation is not allowed. This boils down to the fact that two atoms cannot be closer than the sum of the van der Waals radii of each atom or electron repulsion occurs. Therefore, by determining the values of phi and... 

Mason, J.S. Diversity for drug design A multiple-technique approach. In Exploiting Molecular Diversity, Proceedings of CHI Meeting, Coronado, CA, March 2-4 1998. 

The availability of an extensive data base and corresponding catalyst background may aid the microscopist in the decision making process. The limitation of specimen preparation and beam sensitivity must be recognized and considered in the evaluation process. Finally, use of a multiple technique approach should be implemented whenever possible to ensure that correct interpretation of the chemical and structural properties of the catalyst are made. 

Hemerythiin presents an excellent example of a protein where intermetallic effects are significant and well studied. Often elegant work using multiple techniques has revealed a great deal of information regarding the structure and function of the active site which contains two iron atoms. Various aspects of those studies have been reviewed by Klotz and co-workers47). 

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