Reduction monitored

Method Abs, chemical reduction, monitored by absorption spectroscopy CD, chemical reduction, monitored by CD spectroscopy CD/OTTLE, electrochemical reduction using an optically transparent thin layer (OTTLE) cell, monitored by CD spectroscopy CV, cyclic voltammetry EPR, chemical reduction, monitored by EPR. 

Figure 32 shows typical measurements of the kinetics of light induced (BChl)2 oxidation and dark (BChl)2 reduction monitored by EPR at 14 K [258]. Data is presented for the native RC (QA is ubiquinone-10, UQ10) and for the RC reconstructed with ubiquinone-7, UQ7. Practically no (BChl)2 oxidation was observed upon illumination of the RC from which UQ10 has been extracted and no UQ7 has been added. The rate constants for (BChl)2 and QA recombination for the native RC and RC reconstructed with UQ7 were practically the same 37.2 s 1 and 38.0 s 1, respectively. Thus, UQ10 extraction and its reconstruction with UQ7 can be carried out without any effect on the reactivity of RC. 

FIGURE 12 (A) Endotoxin and (B) DNA reduction monitored during purification steps for... 

The oxidation of the enamine on El in PDHc by nonlipoic acid acceptors has also been explored for many years. For example, ferricyanide reduction monitored by visible spectroscopy has become a standard test to assay El activity, notwithstanding the attendant problems, including the instability of the thiazolium ring to such conditions. 2,6-Dichlorophenolindophenol (DCPIP) has also been used as an alternative electron acceptor in mechanistic studies of PDHcs75. 

Fig. 5. Flash-induced absorbance change due to P700 photooxidation and dark reduction monitored at 703 nm in broken chloro-plasts in the presence of high concentrations of salt and sorbitol. The accompanying table shows effects of salts and sorbitol on the amplitude of P700 re-reduction by plastocyanin. See text for discussion. Figure source Haehnel, Prdpper and Krause (1980) Evidence forcompiexed piastocyanin as the immediate eiectmn donor of P-700. Biochim Biophys Acta 593 387, 389.

Warfarin—(major interaction), results in increased anticoagulant effects, increased risk of bleeding monitor coagulation parameters closely phenytoin—may require phenytoin dose reduction monitor phenytoin levels closely leucovorin increases the activity and toxicity of capecitabine... 

Part 6 External resources for risk reduction, monitoring systems... 

RSSIE in the above systems was investigated by TPR/TG (temperature-programmed reduction monitored by a thermobalance), XRD, TEM/EDAX, XPS and IR. However, in the case of CuO/H-ZSM-5, it turned out that employment of a reducing agent was not necessary for incorporation of Cu cations, since auto-reduction occurred. 

Madey and co-workers followed the reduction of titanium with XPS during the deposition of metal overlayers on TiOi [87]. This shows the reduction of surface TiOj molecules on adsorption of reactive metals. Film growth is readily monitored by the disappearance of the XPS signal from the underlying surface [88, 89]. This approach can be applied to polymer surfaces [90] and to determine the thickness of polymer layers on metals [91]. Because it is often used for chemical analysis, the method is sometimes referred to as electron spectroscopy for chemical analysis (ESCA). Since x-rays are very penetrating, a grazing incidence angle is often used to emphasize the contribution from the surface atoms. 

The concentration of chromic acid can be determined from its reduction by alcohols under conditions when the kinetics are pseudo-first-order in analyte. One approach is to monitor the absorbance of the solution at a wavelength of 355 nm. A standard solution of 5.1 X lO " M chromic acid yields absorbances of 0.855 and 0.709 at, 100 s and 300 s, respectively, after the reaction s initiation. When a sample with an unknown amount of chromic acid is analyzed under... 

The amount of a particular component in a sample can be monitored by examining the height of a spectral absorption peak The reduction of an aldehyde to an alcohol would show up as a decrease in line intensity for the carbonyl and an increase for the hydroxyl peaks in the spectrum. Changes in the relative importance of different relaxation modes in a polymer can also be followed by the corresponding changes in a mechanical spectrum. 

Reduction of the aromatic nuclei contained in catalytic C-9 resins has also been accomplished in the molten state (66). Continuous downward concurrent feeding of molten resin (120°C softening point) and hydrogen to a fixed bed of an alumina supported platinum—mthenium (1.75% Pt—0.25% Ru) catalyst has been shown to reduce approximately 100% of the aromatic nuclei present in the resin. The temperature and pressure required for this process are 295—300°C and 9.8 MPa (lOO kg/cni2), respectively. The extent of hydrogenation was monitored by the percent reduction in the uv absorbance at 274.5 nm. 

The reduction of molybdate salts in acidic solutions leads to the formation of the molybdenum blues (9). Reductants include dithionite, staimous ion, hydrazine, and ascorbate. The molybdenum blues are mixed-valence compounds where the blue color presumably arises from the intervalence Mo(V) — Mo(VI) electronic transition. These can be viewed as intermediate members of the class of mixed oxy hydroxides the end members of which are Mo(VI)02 and Mo(V)0(OH)2 [27845-91-6]. MoO and Mo(VI) solutions have been used as effective detectors of reductants because formation of the blue color can be monitored spectrophotometrically. The nonprotonic oxides of average oxidation state between V and VI are the molybdenum bronzes, known for their metallic luster and used in the formulation of bronze paints (see Paint). 

Air Pollution. Particulates and sulfur dioxide emissions from commercial oil shale operations would require proper control technology. Compliance monitoring carried out at the Unocal Parachute Creek Project for respirable particulates, oxides of nitrogen, and sulfur dioxide from 1986 to 1990 indicate a +99% reduction in sulfur emissions at the retort and shale oil upgrading faciUties. No violations for unauthorized air emissions were issued by the U.S. Environmental Protection Agency during this time (62). 

The reaction in equation 55 occurs when there is insufficient hydrogen peroxide reductant in the absorber solution. Monitoring of the hydrogen peroxide concentration is important because is unstable in strong alkaline solutions, decomposing to water and oxygen. A small excess of sodium hydroxide is... 

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