Transition metal concentrations

Literature values of the active-site concentrations range from tenths or hundredths of a percent to tens of percents of the transition metal concentration [Lieberman and Barbe, 1988 Tait and Watkins, 1989]. Much of this is indicative of the range of activity of different initiators, especially when comparing older initiators to the recent high-mileage initiators. However, some of the variation is due to the problems inherent in measurement of [C ]. Literature values of kp and other rate constants also show a considerable range. 

Similar ponds of metalliferous sediment are observed close to other inactive sulfide stmctures throughout the TAG area (Rona et al., 1993). Metz et al. (1988) characterized the metalliferous sediment in a core raised from a sediment pond close to one such deposit, 2 km NNE of the active TAG mound. That core consisted of alternating dark red-brown layers of weathered sulfide debris and fighter calcareous ooze. Traces of pyrite, chalcopyrite, and sphalerite, together with elevated transition-metal concentrations were found in the dark red-brown layers. 

R p )o is the rate without added water R p and (R p )o are the reduced rates at unit monomer and transition metal concentrations. Taking into account the surface area of the catalyst it was estimated that one molecule of water blocks a site of 35A. ... 

EPDM elastomers Low transition metal concentration in the polymer, MJM = 2... 

Mw/M = 2, highly linear Copolymerization random distribution, LLDPE co-monomers propene, 1-butene, 1-octene Elastomers, Terpolymers of Ethene, Propene and Diene low transition metal concentration in the polymer, narrow molecular weight distribution Polymerization to ... 

Support Precursor Specific surface area OH groups concentration Transition metal concentration... 

The magnetic properties of U-T alloys were studied by Cornelison et al. (1980). It was shown that for U66T34, T = Fe, Co, Ni, a cluster-glass behaviour is found below = 100 K. The magnetic moment was assumed to develop only for relatively high transition-metal concentrations. 

So what can be learned from studies of phenol/ONOO reactions which can benefit the search for and detection of specific ONOO footprints in vivo By far the most abundant phenolic compound in cells and tissues is tyrosine, primarily as residues in proteins. Tyrosine residues are readily nitrated by ONOO without the need for transition metals. Transition metals such as Fe(III) or Cu(II) catalyze nitration, and the nitration yield increases linearly with metal concentration (Beckman eta/., 1992). However, significant increases in nitration yield occur only at transition metal concentrations that exceed those likely to ever be present in vivo. 

In the case of transition metal oxides, solubility considerations of Fe203 and Mn02 suggest that the total dissolved transition metal concentrations in these systems should be far too low, less than 10 mol kg" (17,18,19,20), to be measured by feasible analytical procedures. Buffers equilibrated with CuO had total dissolved copper concentrations of 1.25 X 10" mol kg" for 0.02 1 buffers and 1.47 X 10 mol kg for 0.305 1 buffers, as determined by atomic absorption spectrophotometry. This agrees well with values predicted from equilibrium considerations for CuO of 1.05 X 10" mol kg" and 1.65 X 10 mol kg, respectively. The calculated values included correction for activity coefficients and carbonate, chloro, and hydroxo complexes, and have been described in more detail elsewhere (8). 

It is conceiveable that colloidal mineral matter may have escaped the filter process. For certain of the transition metals concentration remained essentially constant as one might suspect if they are truly soluble organically bound species. Runs 217 and 220 enables one again to observe if processing severity influences metal content. For this coal and these conditions there surprisingly is essentially no change in metal content. 

Figure 4,29 Transition metal concentrations in MORE (from Langmuir et aL, 1977) normalized to chondritic values. The normalizing values are taken from Langmuir et ai. (1977) with the. . . exception of Fe, which was taken from Wood et al. (1979b) — Table 4.12.

Various alumlnoxane containing catalysts are used. Again, the Et(lnd)2ZrCl2/MAO system Is best. The transition metal concentration is In the region of 10 mol/1. 

Random comonomer distribution, LLDPE comonomers propene, higher a-olefins, cycloolefins (COC), dienes. Low transition metal concentration in the polymer, Mw/Mn = 2. 

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