Double crucible technique

Double-cell system, in soil and ground water treatment, 25 835 Double crucible technique, 11 135-136 Double-deck kiln, 15 530 Double-drum dryers, 9 134 Double-drum separator, 15 446 Double-effect distillation, 10 153 Double end point titration method,... 

The preparation of the metal was first reported by von Grosse (80) who obtained it by bombarding protactinium pentoxide with 35 keV electrons in a high vacuum and by decomposing the pentachloride on a hot wire. No properties were reported for these products and more recently the pure metal has been obtained by reduction of protactinium tetrafluoride with lithium (73) or barium (65,125) vapor at 1300°-1400°C using the double crucible technique and on a larger scale by reduction with barium (106) or 10% magnesium in zinc alloy (107). 

H. Tokiwa, Y. Mimura, T. Nakai and 0. Shinbori, Fabrication of long single-mode and multi-mode fluoride glass fibers by the double crucible technique. Electronics Letters, 21 [24], 1130-1131 (1985). 

Early attempts at making low-loss fiber were based on multicomponent compositions. Research was done on such novel processes as the double-crucible technique. The best loss result obtained with such attempts was in hundreds of dB/km. Some of these techniques, although not useful for long-distance fiber applications, have been shown to be useful for specialty appUcations such as amphfier fibers that are doped with rare earth elements. 

After calibration, the measurement technique of specific heat of sample fluids composed of a double experiment performing two nearly identical runs-one with the two cells without sample and the other with the sample in one of the cells. In this way, any differences between the two crucibles are eliminated from the final signal to be used in equation (1). The uncertainty of the heat capacity determinations is found to be better than 1.5% at a 95% confidence level. It is noted that according to the ISO definition, a coverage factor k=2 is used and in order to obtain the accuracy value it must be divided by 2 (Sampaio Nieto de Castro, 1998). We have checked the accuracy of the measurements by measuring the heat capacity of certified reference material sapphire (NIST SRM-707), between room temperature and 430 K, and found deviations of less than 1.5 % with an average absolute deviation (AAD) of 0.68%. 

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