ABSTRACT
Aqueous biphasic systems (ABS) are comprised of both a polymer-rich phase (e.g., polyethylene glycol, PEG) and a salt-rich phase [e.g., (NH4)2SO4] such that both phases are 80% water on a molar basis. ABS have demonstrated applications as environmentally-friendly methods to separate relatively hydrophobic anionic species, such as pertechnetate and mercury halide anionic complexes, from high ionic strength solutions although partitioning of hydrated metal ions, such as Fe3+ and actinides, to the PEG-rich phase is negligible without the addition of a metal ion complexant to the system. Four naphthol- or resorcinol-based dyes; 1-(2-pyridylazo)-2-naphthol (PAN), 1-(thiazolylazo)-2-naphthol (TAN), 4-(2-pyridylazo)-resorcinol (PAR) and 4-(2-thiazolylazo)-resorcinol (TAR), each incorporating a naphthol or resorcinol with an ortho azo functional group, have been studied as metal ion extractants in ABS as a function of pH. In the PEG-2000/ (NH4)2SO4 ABS, the distribution ratios of Fe3+, Co2+ and Ni2- were enhanced by several orders of magnitude at high pH in contrast to the behavior of Cs+, Cd2+ and Eu3+ whose partitioning behavior was largely unaffected by the presence of these extractants at any pH. The three extracted metal ions, Fe3+, Co2+ and Ni2+, could be stripped by contact with a fresh salt phase at low pH.
Subject(s)
Azo Compounds/chemistry , Coloring Agents/chemistry , Metals/chemistry , Naphthols/chemistry , Resorcinols/chemistry , Hydrogen-Ion Concentration , Water/chemistryABSTRACT
We report a simple technique for patterning channelized optical waveguides on standard electronic printed circuit card material. The technique exploits the abundance of transparent, radiant-curing polymer adhesives in the fiber optics and the dental industries. The process is compatible with standard printed circuit card fabrication processes; hence its applicability to optical interconnection scenarios. We report typical guide losses in the 0.4-0.6-dB/cm range. Measurements were made using an automated noninvasive, nondestructive technique, also briefly described here. Simple structures, such as splitters, bus lines, and 90 degrees bends were fabricated and are described. Optical coupling to the waveguides from packaged devices is also discussed.
ABSTRACT
The response of an RCA-4522 photomultiplier tube (35ET bialkali photocathode, 14 dynode stages) in the saturation region has been studied as a function of ambient background light intensity, photocathode illumination area, magnetic field orientation, and ambient temperature. These studies were made using various high-speed pulsed light sources. It is found that the phototube's response does vary with some of these parameters (in particular, photocathode temperature effects). However, its response is reproducible and highly successful operation in this region is possible through a series of calibrations.
