Explanation of Radiation Damage - C&EN Global Enterprise (ACS

Nov 5, 2010 - A research group under K. P. DuBois and coworkers at the United States Air Force radiation laboratory at the University of Chicago, has ...
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RESEARCH

Desalting Sea W a t e r Compression distillation a n d electrical m e m b r a n e processes to be studied under Interior D e p a r t m e n t contracts »-T-«\\O MAJOR contracts for research in

•*· the d e v e l o p m e n t of practical proces­ s e s for conversion of salt water to pot­ a b l e water h a v e been signed b y the D e p a r t m e n t of Interior. Contracts are for $ 8 0 , 0 0 0 w i t h Badger M f g . and $8-8,000 w i t h Ionics. Both c o m p a n i e s a r e in C a m b r i d g e , Mass. In addition to t h e s e t w o contracts, three other explora­ t o r y contracts w e r e let earlier this year b y the d e p a r t m e n t and o n e contract is s t i l l pending. Badger contract is for distillation e q u i p m e n t radically different from that u s e d aboard ship and at a d v a n c e military bases. U n i t has no boiler tubes, ha.s high heat-exchange capacity and h e a t conservation. Unit is e x p e c t e d to operate at five times the heat capacity of existing e q u i p m e n t . It operates under v a c u u m w i t h l o w temperature differentials b e ­ t w e e n evaporation and condensation steps. H i g h heat-exchange rates are ex­ p e c t e d to l o w e r cost of desalting s e a water considerably—perhaps to about o n e fourth present costs. Present contract with Badger is for 1 8 months and, if successful, m a y be ex­ t e n d e d to i n c l u d e design, construction, a n d testing, probably at an oceanside installation w h e r e sea water is available f o r prolonged use. Several California municipalities are among those offering t o cooperate in the tests. Basic research on the compression distillation d e v e l o p m e n t has b e e n con­ d u c t e d b y Kenneth C. D . Hickman, former director of research for Distil­ lation Products, and Gray Dickason, president of Rochester Research Corp., Rochester, N.Y. Electrical M e m b r a n e P r o c e s s . C o n ­ tract w i t h Ionics is an o u t g r o w t h of an earlier contract in w h i c h the electrical m e m b r a n e process u n d e r w e n t rigid laboratory testing on brackish water. Proposal calls for a unit w h i c h has 10 times the capacity of previous appara­ tus t e s t e d for the D e p a r t m e n t of In­ terior. Operation i n the field will eliminate necessity for bringing large quantities of w e s t e r n brackish waters to the labo­ ratory for adequate durability tests. In addition t o saving carrying charges, ex­ posure to field conditions will b e ob­ tained. Field tests are to b e c o n d u c t e d in t w o parts, w i t h provisions for extending them to a third or fourth location. First test of n i n e months will b e c o n d u c t e d

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in central Arizona on saline water. N e e d there is for removal of salt from highly mineralized water used for i m gation which must b e b l e n d e d with pure water before u s e . S e c o n d test will be on a municipal water s u p p l y in t h e Great Plains, w h e r e drinking water has high mineral content. A site in South Dakota has b e e n tentatively selected. It is e x p e c t e d that not only will pota­ bility of this water b e improved, but a water softening effect will result. A third field test m a y b e m a d e on brackish municipal and irrigation waters in t h e lower Rio Grande area. O t h e r P r o p o s a l s . O n e of t h e ex­ ploratory contracts calls for a $ 2 6 , 0 0 0 grant to Nuclear D e v e l o p m e n t Associ­ ates, W h i t e Plains, Ν . Υ., for exploring the possibility of u s i n g critical tempera­ tures and pressures in sea water distil­ lation. Balzard v o n Platen, a S w e d i s h scientist w i t h m u c h experience with this method, has b e e n consulted on the proc­ ess, along with other scientists in Europe a n d North Africa, w h e r e exten­ sive demineralization work is b e i n g d o n e . T h e department feels that t h e proposal for using t h e extremely high pressures and temperatures holds great promise, possibly e x c e e d i n g compres­ sion distillation a n d electrical m e m ­ brane process, if problems of corrosion and scaling can b e overcome.

Polytechnic Institute of Brooklyn has received a $ 3 0 , 0 0 0 contract for explor­ ing ail reasonably promising processes with t h e i d e a that an entirely different type of m e m b r a n e demineralization might be d e v e l o p e d w h i c h w o u l d b e capable of separating different minerals on a s e l e c t i v e basis. T h e Ionics e q u i p ­ ment r e m o v e s all salts regardless of type. A 3 1 5 , 0 0 0 contract w i t h Bjorksten Research Laboratories is o n e of several under consideration for d e v e l o p m e n t of low-cost solar distillation apparatus. It is hoped that substantial reduction in the c o s t of a simple solar still m a y be achieved t h r o u g h u s e of plastic ma­ terials w h i c h Bjorksten d e v e l o p s . Further research i n c l u d e s expanded solar distillation studies, separation of salt f r o m w a t e r b y freezing, and con­ tinuation a n d expansion of work on separation b y osmosis a n d solvent ex­ traction. Work on t h e latter at the Uni­ versity of Florida a n d T e x a s A&M Research F o u n d a t i o n is s h o w i n g satis­ factory results, d e p a r t m e n t says. Re­ search c o m p l e t e d r e c e n t l y includes a study b y Battelle o n utilization of solar heat i n m u l t i p l e effect distillation ap­ paratus a n d a project carried out by Heinz E n g i n e e r i n g o n an improved technique for analyzing vapor compres­ sion c y c l e s . M o r e I d e a s N e e d e d . T h e depart­ ment points out that e v e n w i t h these developments and t h o s e u n d e r g o i n g exploration in the contracts just signed, there is still a n e e d for i d e a s w h i c h m a y bring cost of desalting w a t e r d o w n e v e n furtner.

Explanation of Radiation D a m a g e Air Force researchers use biochemistry to e x p l a i n physiological changes following e x p o s u r e to r a d i a t i o n A T L A N T I C C I T Y . - P h y s i o l o g i c a l dif­ ferences following exposure to radia­ tion can best b e understood, according to some scientists, b y application of t h e discipline of biochemistry. A research group under K. P. D u B o i s and c o ­ workers at the U n i t e d States Air Force radiation laboratory at t h e University of Chicago, h a s b e e n investigating changes of e n z y m e systems of radio­ sensitive tissues. T h e y told t h e annual m e e t i n g here of the Federation of American Societies for Experimental Biology that t h e y h a v e b e e n especially concerned w i t h alterations of e n z y m a t i c activity of the spleen and thymus fol­ lowing exposure to radiation. Cholinesterase Changes. One of the

CHEMICAL

early effects observed following expos­ ure to radiation is a n increase in m o ­ tility of the small intestine, as evi­ denced b y v o m i t i n g a n d diarrhea. These gastrointestinal disorders are similar t o those previously reported as indications of an alteration in t h e acetylcholine-cholinesterase e n z y m e sys­ tem. In 1 9 5 2 , J. H . Burns a n d c o ­ workers i n Britain reported there w a s a decrease in activity of this system i n the small intestine f o l l o w i n g radiation. J o h n D o u l l , also at C h i c a g o , n o w says that there is also an alteration of this system i n t h e s p l e e n a n d thymus fol­ lowing exposure to radiation. H o w e v e r , the activity in these tissues is increased within 1 2 hours after exposure, while

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Enzyme systems of radiosensitive tissues were discussed at American Societies for Experimental Biology by John Doull D. F. Petersen of the United States Air Force radiation lab at Others at the lab—Oda K. Cummings and E. M. Ukeki—also

Atlantic City meeting of (left), K, P. DuBois, and the University of Chicago. participated in the studies

activity in the small intestine is de­ creased. With sublethal doses the cholinesterase changes are reversible in all three tissues, returning to normal in about two weeks, according to Doull. High-Energy P h o s p h a t e . An in­ crease in activity of some of the alka­ line phosphatases is also noted b y the Chicago group. After exposure of rats to the sublethal dose of 400 roentgens of x-ray, increases in the adenosine triphosphatase and 5-nucleotidase ac­ tivities of spleen and thymus glands are observed. The increase in activity of these phosphatases is evident within 12 hours after irradiation and increases to over 200% of normal within 72 hours. Coincident with increase in phos­ phatase activity there is a decrease in adenosine triphosphate and total ade­ nosine nucleotides of the tissues, show­ ing that the rise in phosphatase activity causes a lowering of the tissue level of important phosphate esters. These ef­ fects are reversible after sublethal doses but are irreversible after lethal doses of x-ray. In 1949 Harvey Patt and associates at the Argonne Lab reported that cys­ teine administered before radiation exerted a protective action. Similar protective activity for β-mercaptoethylamine was reported by Bacq from Bel­ gium in 1953. These two compounds, which had been reported to have a protective ac­ tion, were tested for their effects on phosphatase activity of the spleen and thymus. They had previously reported that following radiation there was an increase in ability of these enzymes to hydrolyze biologically important phos­ phate esters. The phosphatase activity, which lowers the high energy phosphate in

the tissues, is reversibly increased fol­ lowing exposure to sublethal radiation dosages. Following lethal dosages, the phosphatase enzyme is irreversibly in­ creased. Both cysteine and β-mercaptoethylamine were found to b e capable of diminishing extent of increase only if the drugs are administered before the animal is exposed to radiation. The biological mechanism of this enzyme protection is now being studied by the Chicago group. This is one of the first chemical demonstrations of a protective action of cysteine and βmercaptoethylamine against radiation injury. Fronrisrs in Biochemistry. Present dentitions of the enzyme are outdated, Fritz Lipmann, cowinner of the 1953 Nobel Prize in Chemistry, told the Symposium on Frontiers in Biochemis­ try. In the light of current research, the concept of the enzyme as a bio­ logical catalyst is not adequately de­ scriptive. To illustrate, he discussed a theoretical protein synthesis and pointed out that utilization of phos­ phate bond energy is poorly expressed by calling action of the enzymes in­ volved hydrolytic. Conversion and transmission of energy, h e says, is an important frontier for biochemistry. Research on this problem will require combined services of physicists and physical chemists, as well as biochem­ ists, for it is becoming increasingly ap­ parent that t h e living system must be considered as a constant influx of energy. Hans Krebs, cowinner with Lip­ mann, discussed some recent applica­ tions of the Bohr-Heisenberg theories in quantum physics and their impor­ tance regarding limitations of biochemi­ cal research.

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