Concentration factor /ratio

Stress-concentration factor Ratio of actual stress to calculated stress on an undistributed mechanical member. 

Both families of calixcrown compounds allowed selective removal of i37caesium from sodium containing solutions less than 100 mg of sodium is transported within 24 h for compound 7, whereas more than 95% of trace level caesium is concentrated in the stripping solution. Nitric acid transport, due to the basicity of both the organic diluent and the calixarene, could not be limited to less than 5% (0.05 mol L ) within 24 h, thus leading to concentration factors (ratio of initial waste concentration to final waste concentration) greater than 100 for a single step process. 

The amount of bleed-off required would depend on the nature of the make-up water and the type of conditioning chemicals used. The specialist tower manufacturer, conditioning chemical supplier or water-treatment consultant will advise the maximum concentration factor (the ratio of circulating water concentration to make-up water concentration) which can be allowed. The necessary bleed-off is then given by ... 

Concentration factor the ratio of concentration locally to that in the bulk solution. 

For both coordinated and congruent control, the pH depends upon the phosphate concentration and the sodium to phosphate ratio. Generally, however, phosphates are unsuitable for use at boiler pressures above 100 bar as their low solubility and high concentration factors developed lead to corrosive conditions. 

In Figure 1 dashed squares refer to water bodies, while solid squares refer to solid matter (also containing some water). Plutonium may appear in any of these squares. The ratio of the concentration of plutonium in two adjacent squares is usually referred to as the concentration factor (CF usually from the water to the solid substance), the transfer coefficient (TC usually between two biological species), or the sorption ratio (or between minerals and water). To avoid ambiguity, we shall use the expression distribution coefficient (abbreviated Kd) with unit dimension (Pu amount per kg product divided by Pu amount per kg source). For the transfer of plutonium from A to B, Pu(A) ->- Pu(B), we define... 

The critical parameters for separation by displacement are the displacer concentration, the loading factor (ratio of the sample size to the column saturation capacity) and the column efficiency. The choice of displacer is probably the most critical step. For correct development to occur the adsorption isotherm of the displacer must overlie those of the feed components. The concentration of the i PlAcer controls the separation time and... 

Parenteral products should be formulated to possess sufficient buffer capacity to maintain proper product pH. Factors that influence pH include product degradation, container and stopper effects, diffusion of gases through the closure, and the effect of gases in the product or in the headspace. However, the buffer capacity of a formulation must be readily overcome by the biological fluids thus, the concentration and ratios of buffer ingredients must be carefully selected. 

A method for estimating the TSCF for equation 14.24 is given in Table 14.10. The root concentration factor is also defined in Table 14.10 as the ratio of the contaminant in the roots to the concentration dissolved in the soil water (pg/kg root per pg/L). This is important in estimating the mass of contaminant sorbed to roots in phytoremediation systems. The values of TSCF and RCF for metals depend on the metals redox states and chemical speciation in soil and groundwater. 

Anodonta anatina 0.5-1.0 Bioconcentration factor (ratio PCP in mg/kg FW soft tissues PCP medium in mg/L) during 3-h exposure ranged between 81 and 162 and was independent of water temperature or PCP concentration 59... 

Combined results on ochre-precipitates and water from which they precipitate indicate strong enrichment regarding several relevant metals (Fig. 3). The concentration factor was estimated using the formulation by Munk et al. (2002), which calculates the ratio between the concentration of the elements in the solid and the concentration in the water. 

The concentration factor f> is defined as the ratio of the recycle biomass to effluent biomass concentrations ... 

This method assumes that the response factor is constant over a range of concentrations and it is often more acceptable to determine the response factor for a range of test concentrations. In this method, a calibration curve is produced by incorporating a fixed amount of the internal standard in samples that contain known amounts of the test compound. For each concentration the ratio of peak heights is determined and plotted against concentration (Procedure 3.2). For quantitation of a test sample, the same amount of the internal standard is introduced in its usual way and the ratio of peak heights for the standard and unknown is used to determine the concentration of the unknown from the calibration curve. 

Few reports are available on the potential effect of chemical concentration on the BAF in an aquatic organism (e.g., Mayer, 1976). Yet, a key assumption of EP theory is the independency of BAF relative to exposure concentration. To our knowledge, there is only one report (Huckins et al., 2004) in the peer-reviewed literature, where the effect of chemical exposure level on concentration factors (CFs) or BAFs has been tested in side-by-side BMO and passive sampler exposures. Huckins et al. (2004) defined CF as the ratio of the concentration in a sample matrix (whole body [soft tissues in the case of bivalves] or whole SPMDs) relative to the concentration in the ambient exposure medium at any moment in time, whereas the A sw and BAF (includes biomagnilication) represent the maximal CF. Similar to ATs s and BAFs, CFs are expected to be independent of exposure concentrations, when residue exchange follows first-order kinetics. 

The concentration factor of the brine, the ratio of the concentrate and feed concentrations, can also be calculated. It is given as ... 

For example, a plant operating at a recovery ratio of 90% will have a concentration factor of 10 (i.e., the components in the feed solution are concentrated 10 times). 

The assumption that the activity factor ratio is constant has been found to be valid over large solute concentration ranges for some solutes even at high total ionic strengths. For example, the distribution of radioactively labeled GaCb between diethyl ether and 6M HCl was found to be constant ( fc,Ga 18) at all Ga concentrations between 10 and 10M [1]. 

Solvent extraction can be automated in continuous-flow analysis. For both conventional AutoAnalyzer and flow-injection techniques, analytical methods have been devised incorporating a solvent extraction step. In these methods, a peristaltic pump dehvers the hquid streams, and these are mixed in a mixing coil, often filled with glass ballotini the phases are subsequently separated in a simple separator which allows the aqueous and organic phases to stratify. One or both of these phases can then be resampled into the analyser manifold for further reaction and/or measurement. The sample-to-extractant ratio can be varied within the limits normally applying to such operations, but the maximum concentration factor consistent with good operation is normally about 3 1. 

Layup Young s modulus (GPa) Measured stress concentration factor Predicted stress concentration factor Notched strength, [Pg.344]

A separate effect of concentration is the ratio between the metal ion and the complexant concentrations. This ratio determines, often more than the overall reactant concentrations, the reaction rate, since it controls the concentration of free metal ions in solution. It can also determine the reaction pathway. Further discussion of this factor will be left for the next example (CdSe), since it has been treated in more detail for that case. 

Consider the same unidirectional lamina with the stresses now applied perpendicular to the fiber axis as shown in Fig. 12. The local stress at the fiber matrix interface can be calculated and compared to the nominally applied stress on the whole lamina to give K, the stress concentration factor. The plot of the results of this analysis shows that the interfacial stresses at the point of maximum principal stress can range up to 2.6 times the applied stress depending on the moduli of the constituents and the volume fraction of the reinforcement. For a typical graphite-epoxy composite, with a modulus ratio of 70 and a volume fraction of 70 % the stress concentration factor at the interface is about 2.4. That is, the local stresses at the interface are a factor of 2.4 times greater than the applied stress. 

Fig. 12. A unidirectional lamina under transverse tension. The points of stress concentration are at the dots. The micromechanical analysis shows that the stress concentration factor increases with volume fraction of fiber and fiber to matrix modulus ratio. From Adams et al.70)...

Imposing a shear stress parallel to the fiber axis of a unidirectional composite creates an interfacial shear stress. Because of the disparity in material properties between fiber and matrix, a stress concentration factor can develop at the fiber-matrix interface. Linder longitudinal shear stress as shown by the diagram in Fig. 13, the stress concentration factor is interfacial. The analysis shows that the stress concentration factor can be increased with the constituent shear modulus ratio and volume fraction of fibers in the composite. Under shear loading conditions at the interface, the stress concentration factor can range up to 11. This is a value that is much greater than any of the other loadings have produced at the fiber-matrix interface. 

Another scheme proposed for collecting enough concentrate for animal studies is shown in Figure 1. In this scheme for concentrating 135 gal of water to a 5-gal methylene chloride concentrate, reverse osmosis is used to reduce the initial 2000-gal volume of water to 135 gal, and the CLLE is used to further concentrate the retentate to 5 gal for biological testing. The LLE portion of this scheme was simulated in a set of CLLE evaluation experiments. The concentration factor from 135 to 5 gal is 27 1, which was easily attainable with the CLLE units. The water-to-solvent ratio in the extractors was 10 1, and the additional volume reduction was achieved by solvent distillation in the distillation chambers of the CLLE units. 

Many lines of evidence indicate that the first committed step in de novo purine nucleotide biosynthesis, production of 5-phosphoribosylamine by glutamine PRPP amidotransfer-ase, is rate-limiting for the entire sequence. Consequently, regulation of this enzyme is probably the most important factor in control of purine synthesis de novo (fig. 23.24). The enzyme is inhibited by purine-5 -nucleotides, but the most inhibitory nucleotides vary with the source of the enzyme. Inhibition constants (A, ) are usually in the range 10-3-10-5 M. The maximum effect of this end-product inhibition is produced by certain combinations of nucleotides (e.g., AMP and GMP) in optimum concentrations and ratios, indicating two kinds of inhibitor binding sites. This is an example of a concerted feedback inhibition. 

Another curve in Figure 6.18 is for (l = B/F = 1.8. The required residence time can be reduced by concentrating the recycle stream 25 to 40% when R is between 0.2 and 1.0. When R < 1.2, the part of curve is noted as a dotted line because it may be difficult to reduce the recycle ratio below 0.2 when j8 = 0.8. For example, in order to maintain R = 0.1, The amount of 1.3F needs to be recycled and concentrated to 0.1F, which may be difficult depending on the cell concentration of the outlet. The higher the concentration factor in a filter unit is, the higher the danger of the filter failure can be expected. 

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