Minimum possible concentration

On a volume basis, the most expensive component of flat wall paints is the TiO. Therefore, significant efforts are appHed to reach a standard hiding with the minimum possible level of Ti02. The efficiency of hiding by decreases as the concentration is iacreased above about 10 vol % it... 

The basic guidelines for preventing cracking would seem to be to operate at minimum stress levels, at as low an HjS concentration as possible and to make sure that welding procedures are adequately specified and followed. Furthermore, extensive periods of operation at temperatures that might cause sigma phase formation should be avoided. 

It is assumed that most of the monomer has undergone solution polymerization in a batch reactor resulting in a high solids content and a relatively low monomer concentration, herein designated Mq. At this point a certain amount of initiator is to be added to bring the initiator concentration to Iq. It is desired to reduce the monomer concentration Mq to a final concentration Mf (around 0.5 vol%) in the minimum possible time by proper choice of a temperature policy. 

The objective of the optimization is to find the optimum temperature policy to reduce the monomer concentration from Mg to the final desired concentration Mf in the minimum possible time. This problem can be mathematically formulated as ... 

A series of simulations were performed to study the effect of variables such as initiator concentration, initiator half-life and activation energy on the optimum temperature and optimum time. It was assumed that initially the polymerization mixture contained S volume percent monomer, the rest of the mixture being solvent and polymer formed earlier. It was required to reduce the monomer concentration from S volume percent to 0.S volume percent in the minimum possible time. The kinetic and tbeimodyamnic parameters used are similar to those of free radical polymerization of MMA. The parameter values are given in Appendix B. 

Minimum Possible Concentrations Obviously, the absolute minimum possible concentration of any chemical within any medium occurs when there is only one molecule of the subject chemical in the sample. Knowledge of this concentration will provide a recognizable lower limit to possible sensing. We can find that concentration [25, p. 11] as follows ... 

Therefore, on the basis of one molecule of the target compound present in a standard sample, a gram for soil, or a liter for water or air, we can calculate the minimum possible concentration for that compound in that size sample of soil water or air. Table 1.8 presents those results. This provides an objective lower bound for the LODs. 

TABLE 1.8 Minimum Possible Concentration, Represented by One Molecule of Explosive... 

The introduction of acid and removal of sugars are regulated to permit a minimum of dilute acid to flow over the chips in order to maintain as high a concentration as possible. Delay in removing the sugar after it is produced results in decomposition therefore continuous removal provides the minimum decomposition. 

These authors have also investigated the hydrolysis of acetyl and propionyl cyanides, the former reacting more rapidly than the latter. These two compounds undergo hydrolysis in neutral or alkaline conditions too rapidly to permit accurate measurements by the technique used (recording spectrophotometer). However, since the hydrolysis is inhibited by acids, rates were measured in perchloric acid concentrations of 1-2 M and above. The rate of hydrolysis passes through a minimum at — 8 M perchloric acid concentration. A possible mechanism to explain such inhibition (which is a rare phenomenon) is... 

Calculations which relate the concentration limits to losses by thermal radiation lead to the conclusion that, as the pressure is raised, the minimum possible propagation rate decreases proportionally to p-1/2. Unfortunately, we do not have the data necessary to compare this assertion with experiment. Reliable measurements of the flame velocity (especially for slow flames) at non-atmospheric pressures are rarely encountered. 

Because Mn2+ is a polyvalent cation, its concentration in the final solution feed to the cation columns should be kept below 0.05M to avoid excess competition for resin sites. For the overall process, it is better to use the longer oxidation times than to use higher Mn2+ concentration. Catalyzed oxidation should not be performed until the volume of solution is reduced to the minimum possible volume. 

Easy recognition of the two peaks over a wide range of relative concentrations is possible for Rs = l and this is essentially the practical minimum resolution desirable. It is usually stated that R = 1 corresponds to a peak purity of about 98% however, this is correct only for equal concentrations of the two solutes. As the ratio of relative concentrations of the two solutes deviates from 1, the recovery of the lower concentration solute at a given level of purity becomes poorer. 

Less than 10% of the polyamide produced is made in a flame retardant version. The best system is composed of a combination of red phosphorus and zinc borate (see table above). The only drawback of this system is its color which is restricted to brick red or black. If other colors are required, ammonium polyphosphate is used either in combination with organic flame retardants or with antimony trioxide. It is possible to manufacture a very wide range of colors in the halogen free system. Some systems make use of the addition of novolac or melamine resins. For intumescent applications, ammonium polyphosphate, in combination with other components, is the most frequently used additive. Figure 13.6 shows that fillers such as calcium carbonate and talc (at certain range of concentrations) improve the effectiveness of ammonium polyphosphate. This is both unusual and important. It is unusual because, in most polymers, the addition of fillers has an opposite influence on the efficiency of ammonium polyphosphate and it is important because ammonium polyphosphate must be used in large concentrations (minimum 20%, typical 30%) in order to perform as a flame retardant. 

Many liquid mixtures exhibit azeotropes at intermedrate concentrations such that the liquid and its equilibrium vapor have the same composition. No separation of (his concentration is possible by partial vaporization. A binary mixture may have a minimum bailing azeotrope, where the boiling temperature of the azeotrope is less than that of the pare components, or a maximum boiling azeotrope, where (he boiling temperature is higher (han that of the pare components. About 90% of die known azeotropes are of the minimum variety. 

The final goals of pesticide analyses are to obtain the cleanest possible samples, to determine the minimum possible concentration with the lowest limits of detection, and to avoid pesticide degradation during transfer to the laboratory. All this means that the accuracy and precision of a method for pesticide analysis will be directly dependent on the sample preparation procedure used. This operation is the most time-consuming and labor-intensive task in the analytical scheme. In response to the need for effective, robust, reliable sample preparation, a number of procedures have developed for fast, simple, and, if possible, solvent-free or solvent-minimized operation. Most such procedures, both conventional and new, are used for the analysis of pollutants in air, water, soils, sediments, and biota. ... 

The residue of pale yellow [Rh(NH3)6Cl]Cl2 is recrystallized from a minimum amount of boiling water. (Care must be taken to keep the solution as concentrated as possible to prevent aquation of the complex.) Yield, 1.4 g. (42%). Anal. Calcd. for [Rh(NH3)6Cl]Cl2 Cl (ionic), 24.0 Cl(total), 36.1. Found Cl (ionic), 24.5 Cl (total), 36.1. 

The gaseous phase consists of small-sized spherical bubbles with low volume concentration, so possible interaction between them can be neglected due to their compactness. Bubble radii can range from the minimum radius R of a germ to the maximum radius that can be attained by a bubble that was bom at the bottom of the liquid and has risen to the surface. 

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