Addition duration

Generators radioisotope -Stable current -Require additional duration missions,... 

Although the positive effects of ERT have been well established, it has been shown that the cell proliferative actions of estrogen can increase the incidence of breast cancer in some patients. In addition, duration of exposure to physiological levels of unopposed estrogens is an established risk factor for breast, uterine, and ovarian cancer. In an effort to attain pharmaceutical agents that oppose the carcinogenic... 

Tab. 9 Water addition duration effect on epichlorohydrin HKR yield.

Solution B addition temperature—solution B addition duration... 

Corrective maintenance maintenance action following a failure of the component. The corrective action is assumed to be the replacement of the component. Due to the fact that this event is unscheduled, this action brings an additional duration of 10 h, with respect to the replacement after a control, leading to a total duration of 30 h. In particular, the additional time may be caused by the supplementary time needed for performing the procedure of replacement after failure or to the time elapsed between the occurrence of the failure and the start of the replacement actions. 

As the gelation pH of silica has a drastic effect on the size of the elementary particles of silica (1) its influence has been evaluated for different addition durations. In the case of the semi-continuous process the gelation pH is easily modified by changing the ratio of the reactant fluxes. For the batch process the order of reactant introduction in the reactor must be changed to have an acid pH (silicate poured in acid) or a base pH (acid poured in silicate). As complex modifications can arise in the reaction mechanisms when the order of reactant addition is changed (18) this latter case has not been studied in this work. 

Table 4 is devoted to xerogel characteristics. The semi-continuous mixing of silica reactants favors the formation of large pores for addition durations below 600 s. Beyond this value the effects are weak. Materials prepared at pH value 5.5 have smaller pore volume and surface than those prepared at pH values 9.5. For the two pH values the mean pore radii are nearly similar. 

The characteristics of silica-alumina xerogels evaluated from nitrogen adsorption-desorption isotherms (B.E.T. - surface area B.J.H. calculations for pore r us and volume evaluations) are presented in table 5. The effects evidenced in this table are almost similar to those detected by thermoporometry opening of the texture for simultaneous introduction of silica reactants. This effect exists for addition durations no longer than 600 s. 

Ui Solution C addition temperature (/. Solution B addition temperature t/., Siirrinfi duration of the reaciional medfilfti before the addition of solution B I/j Solution B addition duration L/j Ratio NaOH/C t/. Ratio B/C L/, Soda nature... 

No. e p Sol. C addition T Sol. B addition T Initial stirring duration (min) Sol. B addition duration (min) Ratio NaOH/C Ratio B/C Soda nauirc Re.sponse yield (%)... 

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