Optical monitoring

The radical cations of urazole-annelated azoalkanes 65 were generated by pulse radiolysis and the transients characterized spectrally and kinetically by time-resolved optical monitoring. The initial distonic 1,3 radical cations 66 were detected, and the methyl-substituted 66 further deprotonates to radical 67 (Scheme 1) <1997JA10673>. 

Try to imagine (e.g., from optically monitored stopped-flow experiments) what you can expect to get out of a rapid-freeze experiment, and preevaluate its biological relevance. 

Optical sensors (Figure 1) can be defined as devices for optical monitoring of physical parameters (pressure1, temperature2, etc.) or (bio)chemical properties of a medium by means of optical elements (planar optical waveguides or optical fibres). Chemical or biochemical fibre-optic sensors3 are small devices capable of continuously and reversibly recording the concentration of a (bio)chemical species constructed be means of optical fibres. 

Bello J.M., Stokes D.L., Vo-Dinh T., Titanium-dioxide based substrate for optical monitors in surface-enhanced Raman-scattering analysis, Anal. Chem. 1989 61 1779-1783. 

Xavier M.P., Vallejo B., Marazuela M.D., Moreno-Bondi M.C., Baldini F., Falai A., Fiber optic monitoring of carbamate pesticides using porous glass with covalently bound chlorophenol red, Biosens. Bioelectron., 2000 14 895-905. 

The flocculation and restabilization behaviour indicated by the filtrability results is well matched by other test methods, including simple settling tests and a newly-developed optical monitoring technique (13). All of these methods give essentially the same optimum polymer concentration. 

Optimax reintroduced with OPTICs monitor syndrome 1990 ... 

To achieve better control of the poling, we have developed an on-line electro-optic monitoring technique . The technique is based on the accumulated change of the electro-optic response when the domains grow through the crystal from the patterned side to the opposite side. A He-Ne beam polarized 45° to the z-axis is launched along the x-axis of the crystal (figure 9). When an electric field is applied, the output polarization state of... 

The use of ICG to measure hepatic blood flow and function by spectrophotmet-ric analysis of serial blood samples collected invasively was recognized more than 50 years ago [141], and the concept of non-invasive optical monitoring of physiologic function with ICG is not new [ 142 -146]. However, advances in optical technology and the availability of miniature lasers for biomedical applications have resulted in the development of faster, simpler, and reliable optical methods for monitoring physiologic functions in real-time. While most of these methods rely on the absorption properties of ICG for continuous hepatic func-... 

Experimental systems used in the chemical generation and in situ optical monitoring of nanosized metallic particulate films are illustrated in Fig. 90. A precursor gas (CO, for example) may be injected in the arrangement shown in the upper part of Fig. 90, while that shown in the lower part of Fig. 90 permits the... 

Controlled-current chronoabsorptometry involves the simultaneous optical monitoring of the product or other redox component in the electrode mechanism during a chronopotentiometry experiment [14]. Although this technique has been demonstrated with Sn02 optically transparent electrodes, it has generally received little use, since the resistance effects in thin-film electrodes can give unequal current densities across the electrode face. This results in distorted potential-time and absorbance-time responses. Consequently, the more prevalent spectro-electrochemical methods utilize potential rather than current as the excitation signal. 

Flewelling R. Noninvasive optical monitoring. The biomedical engineering handbook, CRC Press/IEEE Press, Boca Raton, EL, 1995, pp. 1346 1356. 

Betz WJ, Bewick GS (1993) Optical monitoring of transmitter release and synaptic vesicle recycling at the frog neuromuscular junction. J Physiol 460 287-309 Betz WJ, Mao F, Smith CB (1996) Imaging exocytosis and endocytosis. Curr Opin Neurobiol 6 365-71... 

Umbach JA, Grasso A, Zurcher SD et al (1998) Electrical and optical monitoring of a-latrotoxin action at Drosophila neuromuscular junctions. Neuroscience 87 913-24 Ushkaryov YA, Hata Y, Ichtchenko K et al (1994) Conserved domain structure of (i-neurexins. Unusual cleaved signal sequences in receptor-like neuronal cell-surface proteins. J Biol Chem 269 11987-92... 

Hadeishi T, Pollard M, McLaughlin R, et al. 1985. Development of an optical monitor for toxic organic compounds in air. Research Triangle Park, NC U.S. Environmental Protection Agency, ORD, Environmental Monitoring Systems Laboratory EPA/600/4-85-043. NTISPB85-225027... 

Figure 3.24 shows the examples of output data of an eddy current monitor, a friction monitor, an optical monitor, and a vibration monitor. In the eddy current monitor output, the first-layer clear point is shown in actual data and differential data. In the friction monitor output the, Cu clear point is also shown in actual data and differential data. In the optical monitor output, the residual oxide thickness output data using 100-nm waves and 60-nm waves are adopted. Shorter waves can give us the finer information of the film thickness. In the vibration monitor, the end point of STI is shown as an example. 

WTW and RTR control of thickness are improved by the use of end-point detection systems and advanced process control. End-point detection, whether mechanical or optical, monitor the state of the wafer surface (film thickness, reflectivity, etc.) or of the entire polishing system (friction, slurry by products, etc.) in an attempt to predict when the desired amount of material has been removed (i.e., the end of process). End-point detection is most successful in processes where a change in the films on the wafer surface leads to an abrupt change in the optical or mechanical properties of the wafer surface. For example, copper CMP end point is easy to detect by optical means due to the large difference in reflectivity of the copper film compared to the barrier films. In contrast, end-point detection for small amounts of ILD removal is difficult due to the lack of change in the wafer surface or the wafer-pad interface. 

Chou, S., S. Lin, and C. Huang (1997). Application of optical monitor to evaluate the coagulation of pulp wastewater. Water Science Technol., Proc. 7th Int. Workshop on Instrumentation, Control and Automation of Water and Wastewater Treatment and Transport Syst., July 6-9, Brighton, England, 37, 12, 111-119. Elsevier Science Ltd., Exeter, England. 

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