Co-migration

Figure 5.13 Transient CO migration induced by intense pump pulse irradiation.

However, a loss in catalytic activity is generated during dry-wet cycles, corresponding to a decrease in Co2 site occupancy and in a relevant occupation in Ag2. In this position Ag+, half-way between Co2 and Co2a, hinders or interferes with Co migration to the Co2a active sites. 

We suggest that the absence of Ag+ in site Ag2 for Co4.6Ag0.2AF, (= Co4) which could hinder Co migration to the Co2a site and that of Ag°, together with the increased Co4 population lost from the Co2 site after a dry-wet SCR could be responsible for preserving SCR catalytic activity and selectivity for low Ag content bimetallic samples. 

The familiar standard de carbonyl at ion mechanism ( 3, 5) involving a concerted oxidative-addition of aldehyde, CO migration (with subsequent elimination), and reductive-elimination of product, would seem with metalloporphyrins to require coordination numbers higher than six, and in this case Ru(IV) intermediates. Although this is plausible, the data overall strongly suggest a radical mechanism and Ru(III) intermediates. 

One concern relating to SDS-PAGE-based purity analysis is that contaminants of the same molecular mass as the product will go undetected as they will co-migrate with it. Two-dimensional electrophoretic analysis would overcome this eventuality in most instances. 

One putative dechlorination product, 235-24-CB, co-migrates with an isomer, 245-25-CB, which was proposed for further dechlorination. 

The number of system eigen zones is the same as the number of constituents of the BGE. Especially in BGEs using multiple constituents, there is a risk of co-migration of a system zone and an analyte zone. There is a software available to calculate eigen zones. ... 

Most determinations may be performed using standard buffers without any changes. However, in some cases when analytes co-migrate, modification may be required. 

FIGURE 13 Analysis of (I) formic, (2) chloroacetic, (3) acrylic, (4) acetic, (5) methacrylic, (6) propionic acids, between I and 20pg/mL, with 30 mM PDC buffer at pH 5.4. The separation temperature is set at 35°C to lower the pH by 0.02 units, which is sufficient to allow separation of acrylic and acetic acids which otherwise will co-migrate. Octanoic acid (7) is used as internal standard. 

FIGURE 15 Analysis of several anions with 30 mM PDC buffer at pH 5.4. Addition of 3% a-CD improves the separation of nitrate and nitrite, which otherwise will co-migrate. 

Figures 3 and 4 indicate a significant variation in the Mn and Co migration barrier along the Oh Td Oh and Oh Oh paths as the oxidation state changes.

The low electroosmotic flow (EOF) of the PMMA chip material facilitated the rapid switching between analyses of explosive-related cations and anions using the same microchannel and run buffer (and without an EOF modifier) [29], This led to a rapid (<1 min) measurement of seven explosive-related cations and anions down to the low micromolar level. The presence of an 18-crown-6 ether modifier in the run buffer allowed separation of the peaks of the co-migrating ammonium and potassium ions. 

Fischer et al. (212) and Stone et al. (93) encountered a very similar CO migration when they attempted the synthesis of a -phenylmethylidyne... 

There are a number of limitations that reduce the efficiency of 2 DE. Co-migration of proteins to the same location on a 2DE gel can occur. 

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