Indirect examination

Replication and shadowing techniques have been used directly in conjunction with other procedures (extraction replication [127]) or specially prepared samples (epitaxially grown crystals [128]), where specific topics are being addressed [129, 130]. Of particular note in this regard is the work of Wittmann and Lotz, who developed a decoration technique for the study of fold surface conformations in lamellar crystals [131]. 

1 To stain or to etch Staining techniques are derived from similar biological sample preparation procedures and involve two distinct steps. Generally, some suitable staining reagent is first allowed to diffuse into the 

It is clear from the preceding discussion that direct examination, staining and etching-replication techniques all have their strengths and weaknesses. They are therefore complementary approaches to the study of polymer microstructure and the choice of technique depends very much upon the precise problem being addressed [144]. 

Although several specific etchants have been devised [179-182], by far the most successful polymeric etching technique is permanganic etching [143, 183]. Initially reported in 1979, this approach to the study of polymer 

Although the preceding account has concentrated on particular aspects of microscopy, it is clear that, even in the more traditional areas that have been addressed here, microscopy of polymers is a topic that is both varied and rewarding. Limitations of space have inevitably prevented as full a discussion as would be ideal, but it is to be hoped that through reference to the cited works, both additional depth and breadth of information may be obtained. 

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There is little published information that directly examines ethnic differences in olanzapine pharmacokinetics or pharmacodynamics. Indirectly, examining stable... 

The effect of lithium on dopamine [DA] synthesis and transmission has been investigated extensively in preclinical studies by directly determining changes in DA or homovanillic acid and indirectly examining lithium-induced changes in DA-linked behaviors [Bunney and Garland 1984 Bunney and Garland-... 

It is sensitive to motions of most chemical events which in turn provides direct and indirect examination of motions within micro-time scale (milliseconds to nanoseconds, respectively). 

Dietary exposure to PFCs was also indirectly examined by Falandysz et al. [145]. PFSAs and PFCAs were analysed in blood samples collected from adults in Poland. A correlation was observed between PFSA and PFCA concentrations in blood and self-reported Baltic fish consumption. 

The A value, the free-energy difference between the two chair conformations with axial and equatorial alkyl groups, is widely used as a measure of steric size . For all alkyl groups there is less than 7% of the axial conformation present at ambient temperature and direct quantitative observation of the equilibrium is not possible. Historically, indirect examination of conformational equilibria in disubstituted cyclohexanes has been used to predict equilibria in monoalkyl compounds (assuming additivity of substituent effects), and reviews of early work in this field and of the pitfalls encountered have been given... 

However, contrary to the initial premise stated above, most polymeric samples, and particularly those of technological or commercial importance, do not naturally tend to occur in the form of a 50 nm-thick film. For bulk samples to be made amenable to examination by TEM they must therefore be subjected to some initial sample-preparation procedure. Indeed, the problems of sample geometry, beam sensitivity and intrinsically low contrast described above are such that they are often best overcome by the indirect examination of the sample. TEM techniques may therefore be divided into those in which the sample is examined directly and those in which a less direct approach is adopted,... 

External corrosion direct assessment (ECDA) is a structured process that consists of four key steps preassessment, indirect examination, direct examination, and post assessment (Fig. 12.16). ECDA is intended to assist pipeline operators in establishing the integrity of pipelines. The process uses aboveground cathodic protection (CP) survey methods, many of which have been used in the pipeline industry for decades. ECDA further defines the process, validation, and data integration for these survey methods [18]. The ECDA process incorporates standard techniques for compiling historical information, pipeline and soil surveys, external pipeline inspections, and data analyses. 

QSPR and QSAR are useful techniques for predicting properties that would be very dilficult to predict by any other method. This is a somewhat empirical or indirect calculation that ultimately limits the accuracy and amount of information which can be obtained. When other means of computational prediction are not available, these techniques are recommended for use. There are a variety of algorithms in use that are not equivalent. An examination of published results and tests of several techniques are recommended. 

Modern commercial lasers can produce intense beams of monochromatic, coherent radiation. The whole of the UV/visible/IR spectral range is accessible by suitable choice of laser. In mass spectrometry, this light can be used to cause ablation, direct ionization, and indirect ionization (MALDI). Ablation (often together with a secondary ionization mode) and MALDI are particularly important for examining complex, intractable solids and large polar biomolecules, respectively. 

Membrane Cliaraeterization MF membranes are rated bvtliix and pore size. Microfiltration membranes are imiqiielv testable bv direct examination, but since the number of pores that rnav be obsen ed directlv bv microscope is so small, microscopic pore size determination is rnainlv useful for membrane research and verification of other pore-size-determining methods. Furthermore, the most critical dimension rnav not be obseiA able from the surface. Few MF membranes have neat, cvlindrical pores. Indirect means of measurement are generallv superior. Accurate characterization of MF membranes is a continuing research topic for which interested parties should consult the current literature. 

An examination of the above standards as they apply to the gas turbine and its auxiliaries are further examined in this section. The ASME B 133.2 basic gas turbines and the API standard 616, gas turbines for the petroleum, chemical, and gas industry services are intended to cover the minimum specifications necessary to maintain a high degree of reliability in an open-cycle gas turbine for mechanical drive, generator drive, or hot-gas generation. The standard also covers the necessary auxiliary requirements directly or indirectly by referring to other listed standards. 

The effect of sulfur contamination on catalyst activity was examined in a special test run in the SASOL plant. Conversion in 6.3 and 23.8% of the total catalyst bed, taken as an indirect criterion of catalyst activity, is plotted vs. operating time in Figure 3. 

In molecular pharmacology research an indirect proof of a structural model is possible by functional examinations, e.g., by molecular biological experiments. Well-selected site directed mutagenesis and their functional characterization allows confirmation or rejection of a molecular protein model. The process is organized as an iterative procedure, where the biological answer of suggested mutations is used to refine the model. The iteration continues until the model... 

Largely for these reasons, radicals are most often characterized indirectly by examining the products of their reaction. Many of the methods used to study radical reactions have been applied to study initiation of polymerization. Some of these techniques are detailed in Section 3.5. 

Before beginning a size determination, it is customary to look at the material, preferably under a microscope. This examination reveals the approx size range and distribution of the particles, and especially the shapes of the particles and the degree of aggregation. If microscopic examination reveals that the ratios between max and min diameters of individual particles do not exceed 4, and indirect technique for particle size distribution based on sedimentation or elutria-tion may be used. Sedimentation techniques for particle size determination were first used by Hall (Ref 2) in 1904, He showed that the rate of fall of individual particles in a fluid was directly related to the particle size by the hydrodynamic... 

Beside their calculation of direct costs, Stoll et al. (2002a) also examined indirect costs in a German sample of HIV-infected patients after the introduction of HAART. To emphasize the implications of different approaches of indirect costs, the authors determined both costs based on the human capital approach and costs calculated on the friction cost approach. They concluded that indirect costs based on the friction approach per patient in 1997 (US 2,421) add up to only one-tenth of the amount derived from the human capital approach (US 24,639). 

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