Glass water-logged

FIGURE 4.18 Radius of spreading vs. time for the spreading of water droplets on glass surface (log-log plot), diameter of the orifice 0.5 mnr. A / = 0.005 mllmin, experiment 1 / = 0.01 mllmin, experiment 2 4 I = 0.02 mllmin, experiment 3 solid line drawn according to Equation 4.105. 

Avdeef, A., Comer, J. E. A., Thomson, S. J. pH-metric log P. 3. Glass eledrode calibration in methanol-water, applied to pK determination of water-insoluble substances. Anal. Chem. 1993, 65, 42-49. 

Parameters ve, a , x and dispersion values, decay kinetics of trapped electrons in water-alkaline (6M NaOH) glass... 

In this connection there arises a natural question, whether there exists a similar correlation for the parameters ve, ae, and a characterizing the rate of tunneling reactions. The question is answered by Fig. 23(a) and (b) presenting the data of Table 2. As can be seen from the figures, for the reactions of etr in water-alkaline glasses the dependences between log i e, a,., and a in a number of the reactions studied have the form of a field of points, i.e. the compensation effect is missing. This fact, in particular, allows one to conclude that the differences observed in the values of the parameters ve, ae, and a for various reactions reflect the real situation rather than that they are the consequence of systematic errors in measurements or data treatments. 

A systematic study of the effect of temperature on the kinetics of et[. decay in reactions with CrO - and NO, in water-alkaline glasses (10M NaOH) in the time interval 10 6 to 10 3s and over a broad range of temperatures (80-202 K) was carried out in refs. 89 and 90. At low enough temperatures the etr decay curves obtained at different temperatures and presented in the coordinates n(t)/n(t0), log t/ta were shown to coincide. On reaching a certain critical temperature (T 150-170 K), however, the reaction rate increases. 

The thermodynamic stability constant of silver sulfadiazine in water has been measured by Boelema et al. (20). They made use of a microcomputer-controlled titrator and measured simultaneously the pH value with a Radiometer G2040C glass electrode and the silver ion concentration with an Orion research 941600 ion-selective silver sulfide electrode. The measured stability constant and standard deviation were logK=3.62i 0.05 n = 9, temperature 25°C, ionic strength 0.1 (sodium nitrate). The calculated conditional stability constant log K at pH 7.4 was 3.57. 

The chemical speciation of copper in river water and model solutions was investigated by a titration technique in which cupric ion activities were measured at constant pH as the total copper concentration ([Cujoj]) was varied by incremental additions of CUSO4. pCu(-log cupric ion activity) was measured with a cupric ion-selective electrode (Orion 94-29) and pH with a glass electrode (Beckman 39301) both coupled to a single junction Ag/AgCl reference electrode (Orion 90-01) in a temperature controlled (25 + 0.5°C) water bath. Total copper concentrations in the titrated solutions were determined directly by atomic absorption spectrophotometry (Perkin Elmer 603) using a graphite furnace (Perkin Elmer 2200). Measurement of total copper concentrations is necessary because of adsorptive loss of copper from solution onto container and/or electrode surfaces. 

The PTMO-containing materials display a glass transition dispersion that is broader and higher than that of the pure PTMO component. The Tg of pure PTMO of reasonable molecular weight is about -75 °C (45). Figures 9a and 9b show the dynamic mechanical behavior (log storage modulus [E ] and tan 8) of a series of PTMO-containing materials as a function of TEOS content. These materials were made with a functionalized PTMO(2000) and various TEOS contents, with the acid and water contents held constant. 

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