Mobile fraction

Volumetric concentration is the mobile fraction of a component s mass at the nodal block in question, divided by fluid volume there. The concentrations are given from the component masses (Mw, Mi, Mp, and Mm), adjusted for the immobile species, and the fluid volume V as,... 

The extraction by 1N NCI yields 5-10% of total heavy metal content. In case of Fe and Mn, these values are even higher. The maximum contents of mobile fractions of trace elements are monitored in the upper horizon. Thus, the role of evapotranspiration barrier in biogeochemical migration of elements in Dry Desert ecosystems pays a very important role in pollutants exposure. 

Fig. 3. Schematic diagram of the spot photobleaching method of FRAP. (A) Darkened circles represent fluorescently labeled molecules evenly distributed over a two-dimensional surface (assumed to be an infinite plane). (B) White and light gray circles represent the initial postbleach distribution of photobleached molecules within a 1-pm diameter spot. (C) Redistribution of photobleached and unbleached molecules as a consequence of random diffusion over time. (D) Curve representing the fluorescence intensity within the l-pm diameter spot monitored over time arrows a, b, and c indicate the time-points that correspond to their respective panels. The rate of recovery from point b to point c is used to determine the diffusion constant. The magnitude of the recovery is determined by comparing the fluorescence intensity at point c with the initial intensity at point a, and is used to determine the mobile fraction.

Within the subsurface zone, two hquid phase regions can be defined. One region, containing water near the solid surfaces, is considered the most important surface reaction zone. This near solid phase water, which is affected by the sohd phase properties, controls the diffusion of the mobile fraction of the solute adsorbed on the solid phase. The second region constimtes the free water zone, which governs liquid and chemical flow in the porous medium. 

Banfif.ld, J. F. Eggleton, R. A. 1989. Apatite replacement and rare earth mobilization, fractionation, and fixation during weathering. Clays and Clay Minerals, 37, 113-127. 

Prudencio, M. I., Braga, M. A. S. Gouveia, M. A. 1993. REE mobilization, fractionation and precipitation during weathering of basalts. Chemical Geology, 107, 251-254. 

A solution of 4o<-homo-5of-cholest-3-en-l-one (104 mg, 0.26 mmol) in hBuOH (30 mL) in a Pyrex tube was irradiated with a 450-W high-pressure Hg arc under N2 for 17 h. The solvent was removed under reduced pressure to give an oily product (109 mg) which was subjected to preparative layer chromatography (silica gel, hexane) to afford three fractions. The most mobile fraction, lx-vinyl-3,4-bisnor-5 x,l03c-cholestane, was obtained as an oil yield 24mg (23%). 

According to Box 18.5, Eq. 13, the breakthrough time depends on D,eff, that is, on the mobile fraction of the chemical. Here this fraction is given by fia = 0.05. The layer thickness is equal to the depth of the unsaturated zone, 5 = 4 m. 

Although the SEMS represents a marked advance in the state of the art for measurement of aerosol size distribution, an important gap remains in current measurement technology, namely, the ability to make rapid, high-resolution measurements of the accumulation-mode aerosols on-line. The limitation of the DMA or SEMS for measurement of particles larger than 0.2 xm in diameter is the multiple charging that allows particles of two or more different sizes to contribute a given mobility fraction. Regardless of... 

This difftisivity was applied to the mobile fraction of P that is capable of diffusing. In the PREDICT program, equation 57 is used for the first 2 s at peak RTA temperature over the entire P profile with good results (68), provided that the anneal temperature is below 1020 °C. 

Thus, the NMR spectra support the contention that the hairy layer of micelles is formed predominantly from the C-terminal peptide of a proportion (possibly as much as half) of the K-casein molecules. However, the mobile fraction will include contributions from any caseins that have dissociated from the micelles as a result of suspension in the 2H20 buffers and any mobile side chains inside the micelle, as well as the mobile external surface fraction. 

Fig. 9. Plots of mobile fraction(fM) of surface anchored PEO chains against the estimated mean separation D between PEO anchor points on the surface of the particles. The D values were calculated from the particle size and number, assuming that all PEO chains were located at the surface...

PU elastomers based on a polyester diol as the soft block and isocyanate groups coupled via a chain extender as the rigid block, have been investigated. The role of the chain extender is to induce some mobility and disorder within the hard microdomains. The elastomers are selectively deuterated in the rigid block. 2H NMR spectra show the coexistence of a solid and a mobile fraction [89]. The solid fraction shows no onset of fast molecular motions at all, while the mobile fraction increases with temperature. These results suggest that some of the hard microdomains (perhaps the most disordered ones) melt successively when temperature is raised. 

PolyPs, which can be detected by NMR spectroscopy are called NMR-visible , and represent a more mobile fraction of the total PolyP content. Lack of an NMR-visible PolyP signal does not indicate the absence of PolyPs in a sample. Accurate values of the chemical shifts of these signals depend on the pH and residual concentrations of divalent cations in the extract (Pilatus et al., 1989). 

The percent recovery, which is determined as (Y/X) X 100 = % recovery. It gives the mobile fraction of the probe. If the radius of the illuminated area is small compared with the diffusion area (cell, vesicle, etc.) and the molecules are free to diffuse, then the percent recovery must be 100%. On the other hand, if the fluorescence fails to recover to the same intensity observed before the bleaching pulse, then it indicates that a fraction of fluorophores exist, which are immobile on the time scale of the experiment Dj < 10 cm /s). 

All this evidence supports identification of the free water in SC with HOH HOH bonds, the 103 °C DTA peak, and Walkley s freezable water (Figure 18). These data also suggest correlation of the hygroscopic substance, the 114°C peak, and the more mobile of Hansen and Yellin s bound water fractions. Their less mobile fraction probably relates to the 135 °C peak and to protein-water bonding. Perhaps only one of Scheup-lein s hypothetical protein water bonds exists when SC is dehydrated during DTA. 

Four types of colloids were considered in the WIPP program intrinsic actinide colloids, mineral colloids, microbes, and humic acid colloids (US DOE, 1996). Intrinsic actinide colloids, consisting of polymerized hydrated actinide hydroxides, are not stable in the neutral to moderately basic pH conditions expected in the WIPP, and were assumed not to contribute to the total actinide concentrations in solution. Mineral colloids are destabilized and tend to flocculate in the high-ionic-strength WIPP brines (Kelly et al., 1999). In the performance assessment calculations for the WIPP, a highly conservative value of 2.6 X 10 mol actinide per liter, for each actinide, was assumed to be bound to mineral colloids and to contribute to the mobile fraction. Actinides sorbed onto microbes and humic acids were estimated to contribute significantly to the concentration of mobile actinides in WIPP brines as discussed above (Section 9.06.3.2.2). 

A further complication that can detract from the validity of quantitative XPS for the characterization of coke deposits Is the mobility of coke components. After Introduction into ultra-high vacuum this mobile fraction may migrate from the inside of catalyst powder grains to their boundary as analysed by XPS. For certain catalyst systems this phenomenon has been observed. It can be easily identified however since the signal intensity ratio for the coke versus support increases with time the catalyst spent in the spectrometer. For the catalysts in this study no change of the signal ratio with time in the measurement chamber was observed. 

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