Centrifugation analytical models

Conditioning of the manganese oxide suspension with each cation was conducted in a thermostatted cell (25° 0.05°C.) described previously (13). Analyses of residual lithium, potassium, sodium, calcium, and barium were obtained by standard flame photometry techniques on a Beckman DU-2 spectrophotometer with flame attachment. Analyses of copper, nickel, and cobalt were conducted on a Sargent Model XR recording polarograph. Samples for analysis were removed upon equilibration of the system, the solid centrifuged off and analytical concentrations determined from calibration curves. In contrast to Morgan and Stumm (10) who report fairly rapid equilibration, final attainment of equilibrium at constant pH, for example, upon addition of metal ions was often very slow, in some cases of the order of several hours. 

The value of model potentials is not the availability of analytic formulas for vibrational overlap integrals rather, it is the ability to pull together fragmentary information of diverse types into a coherent picture in order to test the observable consequences (location and strength of other perturbations) of alternative assignment schemes (Section 5.1.5). RKR and numerical integration comprise the most convenient way to obtain vi vj) factors and other quantities derivable from V(R) [e.g., centrifugal distortion constants (Albritton, et al, 1973)]. 

Density gradient ultra-centrifugation can be used to determine the buoyant density of DNA and quadruplexes. Sedimentation experiments can also be used to measure sedimentation coefficients and molecular weights. Bead modeling on atomic-level model structures can be used to calculate theoretical hydrodynamic properties of DNA the structures. The calculated hydrodynamic properties (translational diffusion, sedimentation coefficients (S) and correlation times) in conjunction with the program HYDROPRO has been used to help differentiate between known or inferred structural conformations measured by analytical ultra-centrifugation. 

Plasma was separated by centrifugation and the concentrations of total (deuterated and protonated) /3-carotene and total retinol in all plasma specimens (after saponification) were measured by high-performance liquid chromatography (HPLC) the fractional standard deviation (FSD) of the analytical method was <0.04. Ratios of /3-carotene-dg//3-carotene in all plasma specimens were determined by HPLC the FSD of this analytical method was 0.0325. Ratios of retinol-dVretinol in all plasma specimens were determined by gas chromatography mass spectrometry the FSD of this method was 0.045. Details of these laboratory analytical procedures are previously described (Handelman etal., 1993 Dueker etaL, 1993,1994). The physiologic compartmental model of the dynamics of /3-carotene metabolism based on these data is also previously described (Novotny et al.,... 

Nature of the Suppression Effect of Caraway Seed. Since analytical data demonstrated that the addition of caraway seeds depleted volatile sulfur compounds in sauerkraut, this effect was studied using aqueous extracts of caraway seeds and authentic volatile sulfur compounds in model systems. Cell-free crude caraway seed extracts were prepared by blending the unheated spice seeds with chilled (ice water) potassium phosphate solutions (50 mM, pH 7) containing 0.1 M potassium chloride (1 5, w/w) in a cold room (4°C). Homogenates were then clarified by filtration and centrifugation as described by Chin (21). Data in Figure 7 shows that unheated and heat-treated crude caraway seed extracts (1 mL in a 3 mL buffered solution, pH 8) removed methanethiol (10 pg) from the headsapce in closed serum-type vials (120 mL) at 37 which indicated that both heat-stable and heat-labile entities in caraway seed were involved in the depletion of methanethiol. 

Evaluation of Long Term Stability of Model Emulsions by Multisample Analytical Centrifugation... 

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