Characterization direct techniques

The results described above demonstrate the utility of this AW technique [135] for characterizing thin film microstructure. This technique uses the well-established nitrogen adsorption isotherm technique commonly used to evaluate porous bulk samples. By increasing the sensitivity to the amount of adsorbed Na, this AW technique allows thin films to be characterized directly. 

Genetic variability [57] Contribution of a genetic polymorphism to the overall metabolism and clearance Recombinants or characterized subcellular preparations the most direct techniques characterized cells for confirmation Gene variant screening rapid, but functional information may be lacking... 

All direct depth profiling techniques used to study the surface segregation from binary polymer mixtures have a depth resolution [29] p limited to some 5-40 nm HWHM (half width at half maximum of the related Gaussian function). They cannot observe the real composition profile < )(z) (for the sake of comparison mimicked by mean field prediction (dashed line) in Fig. 16a) but rather its convolution (solid line in Fig. 16a) with an instrumental resolution function characterized by p. The total surface excess z however provides a good parameter, independent of resolution, as it has been concluded based on experimental data obtained using different direct techniques [170]. 

Gel electrophoresis is a powerful and versatile method to resolve mixtures of different nucleic acid molecules and allows the fractionated molecules (i) to be viewed directly, (ii) to be recovered in pure form or (iii) to be characterized directly by hybridization. Hybridization of the probes to fractionated DNA ( Southern technique ) (Southern, 1975) or fractionated RNA ( Northern technique ) (Al-wine et al., 1979) can be achieved after the transfer of the resolved molecules to a membrane, but in some cases also directly in the gel using oligonucleotide probes ( unblot ) (Purrello and Balazs, 1983 Tsao et al., 1983). The steps in these protocols are summarized in Table 9.1. Simultaneous extraction of DNA and RNA (Section 3.4.3) (Chan et al., 1988) may be advantageous when the mass of tissue available is small. 

Particle size characterization techniques can be broadly classified as direct and indirect techniques. In the direct techniques, the characterization is performed directly on the actual particle, whereas in the indirect techniques, the characterization relies on relationships between physical properties and particle size or shape. 

The direct techniques of particle size characterization include sieving and various microscopic methods, each discussed briefly. Details can be... 

Finally, it is important to acquaint readers, particularly those more familiar with electrophoretic separations than materials characterization, with techniques that can be used to characterize different substrate materials and coatings. The direct analysis of the interior of capillaries is challenging so most of the methods discussed below are measured on a comparable flat surface. While it can be debated whether this approach is reasonable for traditional fused silica capillaries, the analogy between a flat surface of the material and the surface of the capillary in a microchip device is quite reasonable. The characterization methods that will be discussed here range from measurements of EOF to analysis of surface chemistry using X-ray spectroscopy techniques, with an emphasis on both how the measurement techniques are applied to materials used for electrophoresis and on how the results can be used to improve separation performance. 

In this section, we review three representative cases of flow-induced mesophases. PET serves as an example of a semi-rigid polymer with intrinsic rigid building blocks. The shear-induced smectic ordering in the flexible-chain polymer iPP provides a special case of induced rigidity, which is still far from fully understood. PDES has been chosen as an example of a stretch-induced condis crystal. Various experimental techniques have been employed to characterize flow-induced mesophases. While scattering methods probe the ordering, a direct technique to measure the molecular mobility is nuclear... 

Highlights Practically all uranium compounds that can be dissolved can be analyzed by the same techniques for the uranium content, isotopic composition, and impurities concentrations that are used to characterize UO2 or UFg. This includes metallic uranium and uranium alloys. An alternative approach is to oxidize the metal to form U3OS that may then be characterized directly as a solid by DC-Arc. 

If the primary aim is to characterize the nonlinear absorption, several direct techniques are more easily implemented or interpreted. Conceptually, the simplest technique is to measure the transmitted intensity as a fimction of the incident intensity on the sample. Separating the linear and nonlinear contributions depends upon the spatial and temporal characteristics of the laser, however, as well as the thickness L and reflectivity R of the sample surfaces. For example, if the laser provides a CW beam of uniform spatial intensity, normally incident on a sample, the transmission T may be expressed as a product T = TlTVi, of the linear transmission Tl = (1-R ) and a nonlinear factor = l/d + f)... 

KH(CF3C00)2) or KHCO3 are clearly characterized. Direct measurements of effective oscillator masses for proton modes are totally new information that could not be obtained with optical techniques. 

SHG is certainly one of the most direct techniques able to characterize NLO properties of second order materials. By using polarized radiation incident on a nonlinear material, being the direction 3 the optical axis of the nonlinear material with reference to Fig. 3.3, it can be shown that SH intensity for the two polarizations (S and P) is given by [23] ... 

Though TGA/DSC and DMA are extremely useful for polymer characterization, these techniques provide no (direct) structural information. As an alternative, structural information such as conformational changes of noncrystalline macromolecules may be determined by small-angle scattering (SAS) techniques. 

The monodisperse nanoparticles will be characterized directly in the microemulsion or after transferring them in another medium. First, the size of the nanoparticles will be determined as a function of various parameters. Their composition will be analyzed by X-ray photoelectron spectroscopy (XPS) or energy dispersive X-ray analysis (EDX). The specific surface area is determined by the BET technique. The direct solvation is analyzed by multinuclear magnetic resonance spectroscopy. 

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