Oxygen microelectrode

Diffusive boundary iayer at the sediment-water interface measured with oxygen microelectrodes in Danish coastai sediments in a totai water depth of 15m. Source-. After Gundersen, J. K., and B. B. Jorgensen (1990). Nature 345, 604-607. 

Hybride micro-FIA systems produced in silicon technology using oxygen microelectrodes and microcavities have been developed for measuring phosphate concentrations [96]. Multiple analyte biosensor arrays can also be realized using thin film and silicon technology. The so-called containment technology has been applied to immobilize enzymes in three dimensional cavities formed in silicon wafers to get fully process compatible biosensor devices [97] (Fig. 5). 

Similar rate studies in waterlogged boreal bogs required modified techniques (Whalen and Reeburgh, 2000a). Oxygen microelectrode studies... 

Archer D., Emerson S., and Smith C. R. (1989b) Direct measurement of the diffusive sublayer at the deep sea floor using oxygen microelectrodes. Nature 340, 623-626. 

N.P. Revsbech (1989). An oxygen microelectrode with a guard cathode. Limnol. Oceanogr., 34,474-478. 

Fig. 51. Structure of an oxygen microelectrode. (Redrawn from Miyahara et al., 1983).

Revsbech, N.P., Madsen, B. and J0rgensen, B.B. (1986) Oxygen production and consumption in sediments determined at high spatial resolution by computer simulation of oxygen microelectrode data. Limnology and Oceanography, 31, 293-304. 

The basic construction principle underlying the function of an oxygen microelectrode is shown in Figure 3.20, after a publication by Revsbech... 

Fig. 3.22 Diffusive boundary layer at the sediment/bottom water transition measured with oxygen microelectrodes. Profiles are shown in both representations on the left. The two representations on the right show the respective spatial patterns. In the above right corner, the surface is shown, whereas the subsurface of the diffusive boundary layer is shown below (after Gundersen and Jorgensen 1990).

To illustrate the general trend of decreasing respiration processes from the continental margin to the deep-sea. Figure 6.20 shows the results of in situ oxygen microelectrode measurements for... 

FIGURE 6.19 Spatial distribution of oxygen within a soil aggregate measured by oxygen microelectrode. Center of the aggregate showing anaerobic conditions (Sexstone et ah, 1985). 

Oxygen microelectrodes, similar to those described by Revsbech (1989), have been used to determine the ROL and thickness of aerobic layers around the roots. Oxygen-depleted hydroponic soln-tions used in many ROL experiments are, however, a poor analog of wetland soil, because they do not mimic the high oxygen demand and low redox potentials found in wetland soil (DeLanne et al.,... 

Figure 17-3 Clark oxygen microelectrode used to measure dissolved O2 in marine sediment in Box 6-1. The tip of the cathode is plated with Au, which is less prone than Pt to fouling by adsorption of species from the test solution. [Adapted from N. P. Revsbech, Limnol. Oceanogr. 1989,34, 474.]...

Aquino-Parsons C, Luo C, Vikse CM, Olive PL (1999) Comparison between the comet assay and the oxygen microelectrode for measurement of tumor hypoxia. Radiother Oncol 51 179-185... 

Le QT, Kovacs MS, Dorie MJ, Koong A, Terris DJ, Pinto HA, Goffinet DR, Nowels K, Bloch D, Brown JM (2003) Comparison of the comet assay and the oxygen microelectrode for measuring tumor oxygenation in head-and-neck cancer patients. Int J Radiat Oncol Biol Phys 56 375-383... 

The apparatus used for these experiments, shown in Fig. 17.6, consists of a reaction vessel, means of measuring the NADH (absorption) and O2 (with an oxygen microelectrode) concentrations, and devices for a constant and oscillatory infiux of O2. 

To the scanning system of the scanning vibrating electrode (SVE), an oxygen microelectrode and a pH microelectrode were added. The three microelectrodes (DO, pH, and SVE) were positioned about 140 pm above the sample and 700 pm apart along a line parallel to the x scan axis. By this setup the concentration of oxygen, the pH, and the ionic current density can be measured almost simultaneously at the same spot. Since local anodic currents should lead to a... 

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