Solution rate tests

Edwards e/a/. carried out controlled potential, slow strain-rate tests on Zimaloy (a cobalt-chromium-molybdenum implant alloy) in Ringer s solution at 37°C and showed that hydrogen absorption may degrade the mechanical properties of the alloy. Potentials were controlled so that the tensile sample was either cathodic or anodic with respect to the metal s free corrosion potential. Hydrogen was generated on the sample surface when the specimen was cathodic, and dissolution of the sample was encouraged when the sample was anodic. The results of these controlled potential tests showed no susceptibility of this alloy to SCC at anodic potentials. 

Fig. 8.15 Effects of potential upon the stress-corrosion cracking of various steels in CO3-HCO3 solution in slow strain rate tests (after Parkins et al )...

For this study, mass transfer and surface diffusions coefficients were estimated for each species from single solute batch reactor data by utilizing the multicomponent rate equations for each solute. A numerical procedure was employed to solve the single solute rate equations, and this was coupled with a parameter estimation procedure to estimate the mass transfer and surface diffusion coefficients (20). The program uses the principal axis method of Brent (21) for finding the minimum of a function, and searches for parameter values of mass transfer and surface diffusion coefficients that will minimize the sum of the square of the difference between experimental and computed values of adsorption rates. The mass transfer and surface coefficients estimated for each solute are shown in Table 2. These estimated coefficients were tested with other single solute rate experiments with different initial concentrations and different amounts of adsorbent and were found to predict... 

In Vivo Test of the Infusion Device. Before the infusion device was used to deliver micro-volume of a heparin solution, the amount of the anticoagulant required to delay the normal clotting time from 1.02 min to > 15 min was determined. An intraperitoneal silicone catheter was inserted by way of a trocar needle into an anesthetized Wistar rat, and the external catheter end was connected to the flow rate testing assembly. With a glass hollow fibre flow moderator having a flow rate of 50 plitre/hr at 48 kPa driving pressure, it was found to require about 25 IU/kg/hr to obtain a Lee-White... 

The cold solution is poured immediately into a previously assembled apparatus, consisting of a 5-1. three-necked flask, immersed in a 20-in. tub of ice-salt mixture (Note 6), and provided with a stirrer, dropping funnel, and thermometer for reading low temperatures. The solution is neutralized by the addition of 600-700 cc. of concentrated ammonium hydroxide (sp. gr. 0.90) at such a rate that the temperature never exceeds —5° (Note 7) the tip of the dropping funnel should be placed directly over the vortex created by the stirrer. After 500 cc. of ammonium hydroxide has been added, the solution is tested with Congo red paper at intervals corresponding to the addition of 50 cc. of ammonium hydroxide three to four hours is required for the neutralization. An additional 100 cc. of ammonium hydroxide is then added. 

In the CSIRO survey of Papua-New Guinea plants, a somewhat more elaborate testing method [19] was adopted finely ground plant material was extracted with ammoniacal chloroform, then the filtered extract was shaken with sufficient dilute acid to neutralise the ammonia and to extract any alkaloid present. The clarified acid solution was tested with Mayer s reagent, and the result rated as - or + to ++++ as in the case of Webb s surveys. The necessary equipment was designed to fit into a portable kit that could be taken into the field. The same procedure was used in some later screens of mainland Australian plants by the CSIRO [20] and in the surveys of orchidaceous plants [24, 25] also in the Tasmanian survey, with some modifications to make it more convenient under field conditions [22]. 

Fig. 7.78 Stress corrosion potential ranges of pipeline steel in hydroxide, carbonate-bicarbonate, and nitrate solutions in slow strain-rate test. Strain rate 2.5 x 10 6 s 1. Arrows indicate open circuit corrosion potentials for each environment. Redrawn from Ref 68...

Discussion The rate at which most reactions take place is approximately doubled for an increase in temperature of ten degrees. In the experiment described below determinations at two temperatures are made of the time required to reduce a solution of potassium permanganate by means of iron and sulphuric acid. Potassium permanganate has a purple color and is converted by reduction into a colorless compound. All the conditions except the temperature are kept constant by using equal volumes of the same solution in test tubes of the same size the iron is used in the form of nails so that the surface of the metal in each case is the same. 

Fig. I Rate of inactivation of compounds (9) and (15), assessed by bioassay against UV4. Compounds were incubated at 10 //M (compound 15) and 60 nM (compound 9) at 37°C in medium (p), medium + 10% fetal calf serum (a), or medium + 10% FCS + lethally-irradiated UV4 feeder cells (. Stock solutions in 0.01 M HCl (15) or acetone (9) were held at 0 C and similarly assayed at intervals Percentage bioactivity remaining was calculated as IC,. (stock solution/lC.. test solution).

One important parameter in the rate at which remediation of the undesirable contaminants occurs is the surface area of the Fe particles. Ponder and Coworkers (50) have specifically addressed this question by using Fe ) particles, 10 to 30 nm in diameter, in the presence of a support material such as polymeric resin, silica gel, or sand. The use of a support prevents agglomeration of the iron and therefore presents a higher specific surface area of iron to the aqueous stream. These supported iron particles, referred to as Ferragel, were tested for their ability to separate and immobilize Cr(VI) and Pb(II) ions from aqueous solutions. Rates of remediation of Cr(VI) and... 

A polymer solution was tested in a cone-and-plate viscometer (cone angle 0.1 rad and cone radius 25 mm) at various rotational speeds. Use the following torque - speed data to infer shear stress-shear rate behaviour and suggest an appropriate fluid model to describe the fluid behaviour. 

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