Calcium ionic strength dependence

However, the dissociation constant Kq) does depend on pH, ionic strength, and the concentration of free Mg +, which need to be estimated independently. 5FBAPTA has been used extensively [308] in studies of cells [306,309,310], and the perfused beating heart, revealing calcium transients during the myocardial cycle (Fig. 11) [311-313]. Kirschenlohr et al. [313] reported that developed pressure in the perfused heart was reduced after addition of 5FBAPTA, but this could be reversed by including 50 pM ZnC in the perfusion medium. 

Dependence of the Negative Logarithms of the Dissociation Constants of Calcium Polyphosphates on the Anion Chain Lengths and the Ionic Strengths of the Solutions... 

Traditionally, recommendations for maximum calcium hardness have suggested levels of 800 ppm Ca hardness as CaCC>3. This is an oversimplification and depends greatly on a number of factors (see Critical Factors for Scale Deposition and Cycles of Concentration, Sections 10.8.11 and 10.8.12). In practice, many cooling systems with high-ionic-strength makeup water supplies can tolerate 1200 to 1400 ppm Ca hardness as CaCC>3 with a suitable and comprehensive treatment program. 

The results of these studies confirm the suggestions made earlier that the nature of the calcium phosphate phase which forms in the precipitation process is dependent not only upon the supersaturation, ionic strength, and pH, but also upon the rate at which reactions proceed. 

Carbonate alkalinity is not a directly analyzable quantity, but it can be derived from the titration alkalinity (A ) by a relationship which is temperature and pressure dependent. pH is also variable with pressure and temperature. In addition, pH can be defined several ways depending on which buffer system is used, whether liquid junction potentials are considered, and what definition of ionic strength is used. The values of the apparent dissociation constants and calcium carbonate solubility constants are dependent on exactly what definition of seawater pH is used and what standardization technique is used (15, 16, 17). 

Figure 10 compares the CO2 and H dependence of dissolution rate observed by Berner and Morse ( 3) far from equilibrium in pseudo-sea water (a CaClz - NaCl solution of the ionic strength and total calcium content of sea water) with the PCO2 aH" dependence given by equation 1. We have found that the rate of dissolution far from equilibrium becomes independent of PCO2 be-... 

To establish a good in vitro/in vivo correlation, the composition and ionic strength of the receptor solution must be adjusted. For fentanyl, the best correlation was obtained with a receptor solution comprised of a 10-fold dilution of modified Dulbecco phosphate-buffered saline (without calcium or magnesium) at pH 7.4. The currents tested in vitro ranged from 0 to 400 pA and were applied to a silver anode and a silver chloride cathode using a constant current power supply. The in vitro data presented in Fig. 5 clearly demonstrate the expected linear dependence of fentanyl delivery on current and the excellent correlation to the in vivo data. 

The electrochemical cell is completed by the external reference electrode, an Ag/AgCl or calomel electrode, which is in contact with the specimen by a liquid/liquid junction or salt bridge of KCl or sodium formate. The potential difference across the cell is logarithmically related to the activity of free calcium ions in the sample by Nernsfs equation. By convention, free calcium is converted from activity to concentration with its activity coefficient, which is itself dependent on ionic strength. 

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