Gradient flow

Gravity settling Elevation gradient Flow pattern Nu. Wcn... 

Figure 12.10 Microcolumn SEC-LC analysis of an acrylonitrile-butadiene-styrene (ABS) teipolymer sample (a) SEC ti ace (b) EC ti ace. SEC conditions fused-silica column (30 cm X 250 mm i.d.) packed with PL-GEL (50 A pore size, 5 mm particle diameter) eluent, THE at a flow rate of 2.0 mL/min injection size, 200 nL UV detection at 254 nm x represents the polymer additive fraction (6 p-L) tr ansferred to EC system. EC conditions NovaPak CIS Column (15 cm X 4.6 mm i.d.) eluent, acetonitrile-water (60 40) to (95 5) in 15 min gradient flow rate of 1.5 mL/min detection at 214 nm. Peaks identification is follows 1, styrene-acrylonitrile 2, styrene 3, benzylbutyl phthalate 4, nonylphenol isomers 5, Vanox 2246 6, Topanol 7, unknown 8, Tinuvin 328 9, Irganox 1076 10, unknown. Reprinted with permission from Ref. (14).

Temperature-entropy diagram, water and steam 814 Temperature gradient, flow over plane surface 688... 

Saurina, J., Hemandez-Cassou, S., Tauler, R., Izquierdo-Ridorsa, A., Spectrophotometric determination of pKa values based on a pH gradient flow-injection system. Anal. Chim. Acta... 

For the required limited dispersion in the above pH and pCa determinations, the analytical read-out had to be made within a residence time of only 5 s however, in the gradient flow injection titration illustrated in Fig. 5.16 and 5.17, and explained on pp. 331-332, the residence time increased from about 0.2 to 6 min (Fig. 5.17) or more. 

FIGURE 14.3 Fast analysis of control drugs and metabolites using a 15 cm x 300 fim inner diameter capillary column packed with 3 /tin C18 particles (Micro-Tech Scientific MC-15-C18SS-320-EU) operated at 10 /tL/min gradient flow rate. UV at 278 nm. (Source Drug Enforcement Administration, Southwest Laboratory, Vista, California and S. DiPari.)... 

Pressure filters, 76 658-659 horizontal belt, 77 379 thickening, 77 382-388 Pressure gauge, 20 645 Pressure gradients, flow caused by, 9 110 Pressure infiltration, of metal-matrix composites, 76 167-169 Pressure injection, moldings, 10 11 Pressure-jump method, 73 427-428... 

Mobile Phase A Mobile Phase B Gradient Flow Rate... 

In Chapter 5, we have studied Morse theory on a symplectic manifold X given by an action of a compact torus T. As noted there, when X is a Kahler manifold, the gradient flow is given by the associated holomorphic action of the complexification T of T. Hence, the stable and the unstable manifolds can be expressed purely in terms of the group action. 

Demare, S., Slater, B., Lacombe, G., Breuzin, D. and Dini, C. (2007) Accurate automated log P-o/w measurement by gradient-flow liquid-liquid partition chromatography Part 1. Neutral compounds./ouma of Chromatography A, 1175, 16-23. 

The important conclusion illustrated by Figures 2.5 and 2.6 is that, although the fluids on either side of a membrane may be at different pressures and concentrations, within a perfect solution-diffusion membrane, there is no pressure gradient—only a concentration gradient. Flow through this type of membrane is expressed by Fick s law, Equation (2.13). 

Figure 63 Schematic of a nanoscale capillary ESI interface. This specialized LC/MS interface, operating at flow rates from 20-500 nL/min and using 50 to 100 pm ID columns, typically provides low femtomole sensitivity. Fully automated sample handling and prearation procedures (i.e., desalting and preconcentration) combined with specialized devices for high separation and variable nL gradient flow rates provide unique capabilities for high-throughput analysis of proteins. (Courtesy of New Objective, Inc., Woburn, Ma., USA.)...

Packing Mobile phase Gradient Flow rate ... 

Fig. 11.10 Piezometric levels (in masl) of the Albian aquifer. Recharge seems to occur in the peripheries, giving rise to down-gradient flow toward Paris in the confined Albian aquifer. This hydrological hypothesis has been tested by 14C dating (Fig. 11.11). (Following Evin and Vuillaume, 1970.)...

Fig. 11.13 Water-level contours of the Watrak Shedi subbasin, western India (April 1978). A gradient of 0.5-0.6m/km is deduced. Down-gradient flow in this 500 km2 basin was hypothesized. (From Borole et al., 1979.)...

Fig. 11.26 4He concentrations relative to 14C ages of waters in the Bunter sandstone wells. 14C ages were calculated from the data of Bath et al. (1979), applying 70 pmc as an initial 14C concentration. The positive correlation validates the relative dating by the two independent methods. Waters of groups A, B, and C have been recharged at different times and do not represent continuous down-gradient flow (see text). 

Andrews et al. (1984) calculated flow velocities of 0.7-4 m/year for the confined Bunter sandstone groundwater system in eastern England. Hence, along the 20-km down-gradient flow in the study area the water should attain a hydraulic age of up to 80,000 years, whereas the corresponding helium age is 300,000 years. 

FIGURE 17-2. Gradient chromatography. Mobile phase H2O to MeOH gradient. Flow rate 2 mL/min. Detector UV at 254 nm, 0.1 AUFS. Sample Blank. Recorder 0.2 in./min. Column Bondapak Cig/Porasil B, 2 mm ID x 60 cm. (Note Actual separation will depend upon the quality of the mobile phase and column packing.)... 

Ronen, D. et al., Characterization of suspended particles collected in groundwater under natural gradient flow conditions, Water Resour. Res., 28, 1279, 1992. 

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