Fractions associated

As with acid-base equilibria, fractions can be defined, e.g. the firaction, a , of the total M 

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Mariotti, A., Mariotti, F., Champigny, M.L., Amarger, N. and Moyse, A. 1982 Nitrogen isotope fractionation associated with nitrate reductase activity and uptake of NO3by pearl millet. Plant Physiology 69 880-884. 

Figure 11.1. A flow-model scheme for treating the protein routing question. Labels refer to flow rates of carbon. The total carbon flux, into and out of the body, is 1, divided into F (for protein) and 1 - F for the remainder. The significant relevant internal fluxes are between the amino acid pool (coupled to the body protein pool), and the energy metabolism pool . The extent to which protein routing is observable in the body protein composition depends on the value ofX (See Fig. 11.2). Numbers in refer to suggested isotopic fractionations associated with a metabolic path, which are consistent with the data of the Ambrose and Norr (1993) and Tieszen and Fagre (1993) data set (see Section 4.1).

DeNiro, M. J. and Epstein, S. (1977) Mechanism of carbon isotope fractionation associated with lipid synthesis. Science 197, 261 263. 

I imagine that respiration adds total dissolved carbon at an isotope ratio of delcorg, specified by subroutine SPECS. I further assume that dissolution adds total carbon at an isotope ratio delcarb, also specified in subroutine SPECS. The precipitation of calcium carbonate removes total carbon at an isotope ratio equal to the isotope ratio of the pore water. There is no fractionation associated with either dissolution or precipitation in this system. Because the isotopic value associated with precipitation is different from that associated with dissolution, I have to test the sign of diss before adding the dissolution term to the equation for the rate of change of the isotope ratio in subroutine EQUATIONS. This test is made in the IF statements in this subroutine. 

Collect the eluate in fractions of about 4 ml and combine the fractions corresponding to each peak. For each combined fraction carry out the determination of nitrogen as per BP (1993). Not more than 10% of the total nitrogen is present in the combined fraction associated with non-retained proteins. 

Isotope fractionation between the vapor phase and the dissolved aqueous phase has been studied only for toluene and trichloroethylene (carbon only [545, 690]). Fractionation associated with adsorption has been quantified only for toluene in regard to sample extraction using a poly(dimethylsilo-xane)-coated solid-phase microextraction fiber [373] and qualified for benzene, toluene, and ethylbenzene based on high-pressure liquid chromatography analyses of isotopically labeled and unlabeled compounds (carbon and hydrogen [692]). Isotope fractionation associated with the reductive dechlorination of chlorinated ethylenes by zero-valent iron and zinc has been... 

Figure 16. Schematic illustration of envelopes of gas species i, in this case Mg, surrounding a volatilizing molten chondrule in space. The size of the gas envelope is a function of ambient background pressure P by virtue of the effect that pressure has on the gas molecule diffusivity D,. The diffusion coefficient can be calculated from the kinetic theory of gases, as shown. The level of isotopic fractionation associated with volatilization of the molten chondrule depends upon the balance between the evaporative flux J vap and the condensation flux Tom When the fluxes are equal (i.e., when = 0), there is no mass-dependent isotope fractionation associated with volatilization. This will be the case when the local partial pressure P, approaches the saturation partial pressure P,...

Reported 5 Cl work related to inorganic environmental problems is more limited. A method for the analysis of chlorates and perchlorates has been developed and used to demonstrate fractionation associated with the microbial degradation of perchlorate with a fractionation factor of 0.985 (Ader et al. 2001 Coleman et al. 2003). Additionally, b Cl has been used to constrain the origin of a Cl-rich plume (Loomis et al. 1998). 

Because this reaction must involve two steps, diffusion of selenate into the interlayer spaces of the green rust followed by electron transfer from Fe(ll) green rust, Johnson and Bullen (2003) interpreted this result using a two-step model similar to that discussed above. The diffusion step presumably has very little isotopic fractionation associated with it. Step 2 might be expected to involve a kinetic isotope effect similar to that observed in the HCl reduction experiments. As is discussed above, if the diffusion step is partially rate-limiting, the isotopic fractionation for the overall process should be less than the kinetic isotope effect occurring at the reduction step. This appears to be the case, as the ese(vi)-se(iv) value of 7.4%o is somewhat smaller than that observed for reduction by strong HCl (12%o). 

Vance, J.E., 1990, Phospholipid synthesis in a membrane fraction associated with mitochondria. J. Biol. Chem. 265 7248-7256. 

So far, only kinetic isotope effects have been considered, but isotopic fractionations associated with equilibrium exchange reactions have been demonstrated for the common inorganic nitrogen compounds (Letolle 1980). Of special importance in this respect is the ammonia volatilization reaction ... 

Characteristics often ascribed to MVT deposits include temperatures generally <200°C and deposition from externally derived fluids, possibly basinal brines. Sulfur isotope valnes from MVT deposits suggest two major sulfide reservoirs, one between -5 and +15%c and one greater than +20%c (Seal 2006). Both sulfide reservoirs can be related, however, to a common sea water sulfate source that has undergone different sulfur fractionation processes. Reduction of sulfate occurs either bacterially or by abiotic thermochemical reduction. High 5 S-values should reflect minimal fractionations associated with thermochemical reduction of sea water sulfate (Jones et al. 1996). 

However, the high affinity is necessary for guanylate cyclase to bind dilute concentrations of nitric oxide. In any equilibrium, the fraction associated as a complex becomes smaller as the concentrations of reactants decrease. 

For the treatment of a mixture of para-H2 and ortho-H2, we next compute reven> the fraction of H2 pairs associated with even (, and r0dd> the fraction associated with odd f, and rno, the fraction without exchange symmetry (para-H2-ortho-H2 pairs). Particle conservation requires... 

Table 1 Excess Risk Fractions Associated with Sleep Hr by Covariates...

If the reaction were followed by monitoring the decrease in pH with time, then, since the [OH ]actual will be altering with time, so will the fraction of Tl+ associated with the ion pair. If the reaction is studied at constant pH, using a pH-stat, then the fraction associated remains constant throughout reaction, thereby simplifying the kinetic analysis. 

In normolipidemic subjects, apoE is found not only in HDLc-like particles but also in two other fractions associated with triglyceride-rich lipoproteins. These are VLDL, and a lipoprotein class intermediate in size between VLDL and LDL (G3). The latter may be the normal counterpart of the (3-VLDL which accumulates in Type III hyperlipoproteinemia and in cholesterol-fed animals. 

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