Comprehensive three-dimensional analysis time

As previously mentioned, the analysis of microfluidic systems can be rather difficult for a variety of reasons. The direct implementation of the Navier-Stokes equations toward surface-directed microfluidic systems requires careful attention when considering the advection of the free surface and the associated curvature of this surface. Consequently, sophisticated computational fluid dynamics software packages are required for a comprehensive three-dimensional analysis of the fluid transport within surface-directed microfluidic devices. However, a time-consuming comprehensive analysis may be beyond the requirements of designing and manufacturing functional surface-directed microfluidic platforms. Consequently, empirical approximations and scaling arguments are commonly used in the characterization of microfluidic physics. 

A new generation of linear ion trap mass spectrometers has been developed and exhibits increased performance compared to traditional three-dimensional (3D) ion traps (Hopfgartner et al., 2003 Douglas et al., 2005). A further evolution of the triple-quadrupole family and ion trap class of instruments is the production of the hybrid triple-quadrupole/linear ion trap (QQQ/LIT) platform. Hybrid instruments of this nature allow for operation in space and not just in time when performing MS/MS analysis. This feature allows for increased performance compared to classical ion traps. A powerful combination possible on a hybrid LIT/QQQ instrument is the ability to use highly sensitive and selective precursor ion, constant neutral loss, and multi-MRM as a survey scan for dependent LIT MS/MS. Compared to a simple MS experiment, these comprehensive triple-quadrupole and LIT modes can be more complex to setup. 

Dinsmore and Weitz (2002) [60] examined a model system of polymethylmethacrylate particles dyed with rhodamine in a density- and refractive-index-matched solution of decalin and cyclohexylbromide. They used CLSM to follow the (very slow) aggregation in real time and determined the particle positions in full three-dimensional detail. From this they performed a comprehensive structural analysis of the gels, including measurement of coordination numbers and backbone fractal dimension of the structures, as well as the much more commonly measured mass fractal dimension. 

Three-dimensional electrodes were mentioned in Section 5.1.1.2. Table 5.4 indicates a potential advantage, namely a high space-time yield. Such electrodes differ from their two-dimensional counterparts in the distribution of potential and current density in the matrix of the electrodes. Rigorous analysis would require evaluation of three-dimensional potential distributions. Fortunately this is often unnecessary one-dimensional approximate models or simplified two-dimensional models are sufficient. A comprehensive treatment of three-dimensional electrodes is beyond the scope of the present text (the reader has already been referred to the review in Ref. 5, particularly for information on fluidized bed electrodes. Further information can be found in Refs. 42-44.) We will concentrate on two limiting types of operation of packed-bed electrodes to illustrate the current distributions encountered and their relationship to scale-up. 

Two-dimensional separations can be performed in different ways. In a comprehensive analysis, the eluate from the first column is transferred to the second column in such a way that three fractions from each first dimension peak is injected and separated by the second dimension column one by one. This requires that the time for the second separation is very fast and equal to or smaller than the first dimension fractionation time. A special interface, a modulator (M), containing a zone that can be cooled and heated, transfers the analytes from the first column to the second dimension. When a comprehensive analysis is performed, 2D data are obtained and are presented as 2D plots. Comprehensive analysis is performed when information about the total sample is desired. When one or a few analytes are to be determined in a complex sample, a simpler method called heart-cut can be used. In this method, only the fraction containing the analyte(s) is transferred to the second dimension for further separation. 

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