Spot deposition

Most of the currently applied LC-MALDI interfaces use off-line spot deposition and a number of commercial instruments are available (Mukhopadhyay 2005). Compared to on-line techniques, this interface type is technically less demanding but only careful adjustment guarantees optimal performance. 

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Figure 3 TEM picture of a typical supported metal catalyst, silver nanoparticles (dark spots) deposited on a high surface area alumina support. (Reprinted from Ref 15. 1998, with permission from Elsevier)...

Figure 3.56. Platinum catalyst (dark spots) deposited on carbon nanohorn substrates in NEC s passive DMFC design (a), compared to Pt deposited on a conventional carbon substate (b). (From Y. Kubo (2004). Micro fuel cells for portable electronics. In Proc. 15 World Flydrogen Energy Conference, Yokohama. Used with permission.)...

Description Visual Spun Tube Spot Deposit AP, mm Hg/time, minutes... 

This compares well with an RSD of 50% in MALDI signal intensities reported for multiple peptide spots deposited from a single capillary using an optimized matrix seed layer technique. Further improvements in deposition volume uniformity were realized for an eight-channel chip containing a methacrylate monolith developed for reversed-phase chromatography in the second separation dimension, with negligible variations at flow rates down to 200 nL/min per channel. 

Table 1. Number of fecal pellets and urine spots deposited by 24...

Bard et al. are using SECM in G/C mode to screen the activity of binary and ternary metallic arrays for electro-reduction of oxygen (54, 1(X), 101). They used the TG/SC described in Section 12.4.3.1 to image the activity of both multi-metaUic and wired enzyme catalyst spots deposited on single glassy carbon substrates (Figures 12.23 and 12.24). Different from the previous approach, the spots do not need to be individually connected... 

One way of forcing the reaction toward high conversion is to combine the catalyst and membrane technologies. The reaction is carried out in a porous membrane tube covered with the catalyst material. The principal concept is shown in Figure 9.18. The reaction proceeds on metal spots deposited on the membrane material. Simultaneously, the smallest product molecules (in this case H2) diffuse out of the system through the membrane. In this way, the equilibrium limitation is removed, and the process proceeds almost as an irreversible reaction in the ideal case. The additional benefit is that the components of the product gas are directly separated, and the construction of a specific separation unit is avoided. For the reactor construction, see Figure 9.19. From the reaction engineering... 

Figure 12.8 (a) Sketch of the spot deposition process with a NADIS tip (b) force curve for a loaded cantilever probe with a 400 nm aperture at tip apex. The schematic labeling shows the probe-surface Interaction (a] approach, (b) jump to contact, (c] contact with the surface until a given applied force, (d) adhesion In the presence of a liquid meniscus, and (e) breaking of the liquid meniscus and pulling off of the tip. 

Figure 12.10 Arraying ultrasmall droplets on amine surface. AFM images of 5 X 5 arrays of nanodroplets deposited with hydrophobic tips. Scale bar 500 nm. [a] 250 nm spots obtained using a tip with an oblong aperture 70 nm X 120 nm [b] 70 nm spots deposited with a 35 nm aperture tip [see Fig. 12.7e] [c] Piot of the spot diameter as a function of aperture size. Errors bars in y correspond to statistics on 25 spots. Errors bars in x reflect the hole anisotropy. The solid line is a guide to the eyes. (Reprinted with permission from Ref. 43, copyright 2007, American Chemical Society.]...

FIGURE 15.8 SPR images of polypyrrole (a) and polypyrrole-oligonucleotide (b) spots deposited by the direct mode of SECM. (From Fortin, E. et al.. Electroanalysis, 17,495, 2005. With permission.)... 

See caption for Table 13.1 for explanation of efficiencies. Data acquired by ablating a portion of a 1-pL spot deposited on target. See text for further explanation of the method of data acquisition. For the chemical structures see the Appendix or Ref. 57. 

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