High-resolution step-scan

With the advent of MDCT, axial step-and-shoot scanning has remained in use for only few clinical ap-phcations, such as head scanning, high-resolution lung scanning, perfusion CT and interventional applications. A detailed theoretical description to predict the performance of MDCT in step-and-shoot mode has been given (Hsieh 2001). 

A typical DNA array fabrication and application process involves three major steps. First, nucleic acids (the capture sequences or probes) are immobilized at discrete positions on surface activated substrates. Secondly, the resulting array is hybridized with a complex mixture of fluorescently labelled nucleic acids (the target), and thirdly subsequent to hybridization, the fluorescent markers are detected using a high-resolution scanning laser that quantifies the interaction. This chapter focuses on the first of these processes and provides the reader with an overview of substrates, surface activation methods and dehvery systems available for nucleic acid immobilization. 

In parallel to these lifetime changes, complexation induces tremendous modifications of the emission spectra, that have been examined for lanthanides in dedicated papers (for example, Hnatejko et al., 2000) or reviewed (Biinzli and Choppin, 1989). Briefly, for Eu(III), taken as a typical example of R(III) ions, the emission arises from the 5Do -> 7Fj transitions, from which the 5Do -> 7F2 (around 616 nm) exhibits hypersensitivity. Therefore, the wealth of information experimentally obtained is highly dependent on the scanning step used and a high resolution is needed to make the best of an emission spectrum (Biinzli and Choppin, 1989). However, even in the case of a low resolution, the changes are spectacular, as illustrated in fig. 7. 

Fig. 10. STM images of 1,3,5,7-cyclooctatetrene on Si( 100) taken at a saturation coverage. (a) Molecules aligned themselves in rows on the two terraces that are separated by a single-height step, (b) Magnified view showing the adsorption pattern, (c) High-resolution scan indicating the presence of a minority species, labelled D . Reprinted from [56] with permission from the American Chemical Society.

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