IRESEARCH
end, tlicy also get a corresponding cyclic series up to a chain length of five. After that the two ends are too far apart to cyelize. Ρ Separating Them. They isolate these pohiners by passing them tlirougii a chromatographic column of diethylaminoethyl cellulose o r similar alkylarriino-substituted celluloses. So far, tlvey have isolated and character· ized tlie 2, 3 , 4, and 5-membered poly mers, both linear and cyclic. They have e-luted! higher members of the series from the cellulose columns but ' have mot yet investigated them. • Making; Mixed Polynucleotides» They tiave also adapted these methods to make di- and trinucleotides having different purine and pyridine bases o n the ribose structure. The secret is t o block t h e phosphate group on the nucleoside containing one base and the hyclroxyl group on the component con taining; the other base. Then react* hydrolyzc, and you have a mixed dinueleotide. With these methods, Khorana says you can build u p in a stepwise and specific fashion higher polynucleo tides. And all these synthetic com pounds contain the typical naturallyoccurring C;{—G.-; internucleotide bonds. • Enzyme Degradation. When you know the exact composition of the polynucleotide, Khorana says, you can determine the mode of action of various enzymes such as nucleases and phos phodiesterases. Once you know that, you then can lise the enzymes with known modes of action on nucleic acids of unknown structures in much the same way that protein chemists have used proteolytic enzymes t o find the sequence of amino acids proteins. Khor ana points out. Khorana and his coworkers have already started this enzyme work us ing t h e well-characterized individual polynucleotides they have made b y the O C C activation technique. They have found, for example, that a snake venom diesterase degrades nucleotide polymers from the end having a free 3'-hydroxyl group and releases nucleoside-o* phosphates successively. Tfciey also have found an enzyme which degrades from the other end— the end having a free o'-hydroxyl and releases nudeoside-3' phosphates. T h e enzyme: a spleen diesterase. Thus, by identifying the nucleoside phos phates, chemists can determine nucleo side sequence in a particular polynu cleotide.
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Toward Lower Pressure Drop Theoretical study of two-fluid system offers hope of reducing pumping costs on long distance pipelines XXJECTXXG water înio oil pipelines may lead to substantial savings in pumping costs, according to the results of a theoretical study in fluid dynamics at Research Council of Alberta, Edmonton, Alberta, Canada. A film of water next to the wail of a pipe can reduce pressure drop per foot as much a s one five hundredths, t h e study predicts. No one has been able to come even close to this potential achievement ( a factor of one twelfth is the best yet reported). But better control o f the location of the interface between water and oil and more complete wetting of the pipe wall by the water p h a s e may be major factors in approaching it, says G. W. Hodgson, head of petroleum research at the Council. Research in his group reveals that using the less viscous water in the area of maximum factional losses—at the pipe wall—should have the same effect as pumping the oil through a pipe moving in the same direction as the oil. Hence, energy loss at the walls should be greatly reduced; less driving force would b e needed to push the oil along at a given
flow rate, Hodgson nninAs o u t Hodgson, along with T. W. p . Russell (now with Union Carbide in Nffontreal) and M. E. Charles, analyzed "~the case of two immiscible fluids flowing concentrically in a circular pipe.** First they had to make several assumptions to handle the mathematics. For example, both fluids have the same density; viscosity of one is mucia greater than that of the other. Also, o i l in the pipe flows at the same volume rate with or without the water. Flow i s laminar, and the fluids are incompressible and Newtonian; the interface is sfcaarp with no mixing of phases. Although reduction in pressure drop should occur under these conditions, no one- has observed them, Hodgson points out. Nonetheless, he feels that th*e biggest problem is the physical one o f getting the two flows concentric. • Big Potential. Admittedly, this work is still theoretical, Hodgson says. But should it lead to a way to get lower pumping costs for heavy crude oils such as are in Alberta's tar sands. It could mean a lot to Canada's econ-
RESEARCH omy. These t a r sand oils are very viscous—up around 100,000 ceotipoise —and present a formidable transportation challenge* since tliey a r e several hundred miles from t h e nearest refineries < near Edmonton ) a n d some 200Û miles from Montreal a n d the big consuming area of eastern C!anada.
In fact» the pipitt£ problem is similar to that of t h e hopeful oil-from-shale industry in Colorado, which gets an oil with high pour point and viscosity from retorting. And, since1 the study is still general (twotoiniseible fluids), it may find application for other pumping problems.
Digitals Scale N e w Heights ADL's computer applications ore geared for CPI# typify today's applications research trend JLEAIMNC;
computer
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search teams a r e zeroing in on t h e chemical process industries with a flock of new uses for digitals. Take Arthur D. Little for o n e example. Here, researchers work at digital applications that range from predicting properties of yet-to-be-made high polymers and combustion rates of rocket fuels, to shedding light on liquid heliums behavior near absolute zero. These applications
