9 research outputs found
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Status of /sup 241/Am recovery and purification at Los Alamos Scientific Laboratory
Americium recovery was initiated at Los Alamos Scientific Laboratory (LASL) in the late 1940's. The early procedures separated gram quantities of americium from large amounts of impurities including plutonium and the rare earths. Ion exchange procedures were developed for further purification. Until recently, no routine processing of americium has been done at LASL for several years. The increasing demand for americium in oil-well logging instruments and other uses led LASL to develop and install a process to recover larger quantities of americium. The LASL process was developed around the chemistry of americium that had been elucidated both at LASL and at other facilities. Presently, the americium feed is obtained as a by-product from a plutonium purification process at the new plutonium facility at LASL. This feed filtrate from a peroxide precipitation process is precipitated as a slurry of hydroxides, filtered, dissolved in nitric acid, and passed through an anion exchange column to remove any residual plutonium. The americium, contained in the effluent, is precipitated as the oxalate and calcined to the oxide. Americium is also available in other highly salted acidic process streams. These should lend themselves to solvent extraction. Developmental work has been promising, and a dibutyl butyl phosphate-kerosene extraction process is being brought on-line
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Solvent extraction of thorium from nitrate solutions by dibutyl butylphosphonate in Isopar H
Solvent extraction of thorium by 30 vol % dibutyl butylphosphonate-70 vol % Isopar H from salted and nonsalted nitric acid solutions was studied. Thorium distribution coefficients D/sub Th/'s were obtained for nitric acid solutions of approx. 0.3 to approx. 12 N and for solutions of 1 and 2 M NH/sub 4/NO/sub 3/ over the HNO/sub 3/ concentration range of approx. 0.5 to approx. 9 N. The nitric acid solution D/sub Th/'s varied from approx. 4.3 at the lowest acidity, increased to a maximum of approx. 40 at approx. 3-4 N H/sup +/, and then gradually decreased to approx. 18 at approx. 11.5 N H/sup +/. The solutions containing 1 and 2 M NH/sub 4/NO/sub 3/ gave definite salting-out effects with D/sub Th/'s of 79 to 90, respectively, at the lowest acidities; these values then decreased with acidity increases to those of the nonsalted acid solutions at approx. 5 N HNO/sub 3/ and paralleled the acid solution values up to approx. 12 N
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Development of particles coated with pyrolytic carbon. IX. Studies of commercial experimental coated particles
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DEVELOPMENT OF A BATCH PROCESS FOR THE PRODUCTION OF A ZrO-UO SOLID SOLUTION
A batch process on the 2 kg scale was developed for the production of ZrO/sub 2/--UO/sub 2/ solid solution in the weight proportion of about 4 to 1. The product is tetragonal ZrO/sub 2/-- UO/sub 2/ solution, with no UO/sub 2/ lines showing on the x-ray powder diffraction patterns. The solid solution is prepared from a precipitate of Zr(OH)/sub 4/-- (NH/sub 4/)/sub 2/U /sub 2O/sub 7/ which is filtered, dried, milled, screened to minus 325 mesh, and heated at 9OO deg C in H/sub 2/ for 4 hours. The success of the preparation depends strongly on the conditions of the precipitation, with precipitation from dilute salt solution being necessary to avoid undissolved UO/sub 2/ in the final product. (auth
Structural modulation of the biological activity of gold nanoparticles functionalized with a carbonic anhydrase inhibitor
Gold nanoparticles (AuNPs) have gained attention for their potential and application in different fields, e.g. nanomedicine. This study explores the surface functionalization of AuNP with inhibitors of carbonic anhydrases (CAs, EC 4.2.1.1). Some CA transmembrane isoforms have been recognized as therapeutic targets for the treatment of hypoxic tumors. Embedding a CA inhibitory function onto a nanosized unit has been proved to enable selective targeting of transmembrane isoforms. We report the preparation in aqueous media, the characterization and CA inhibition tests of AuNPs coated with a sulfonamide (SA) derivative, already known for its inhibitory activity toward CAs. The physico-chemical characterization of SA-coated AuNPs was performed with a combination of scattering and spectroscopic techniques. We detect a threshold effect of the SA concentration on the final hydrodynamic and core sizes of the capped nanoparticles and on their stability over aggregation. These modified nanoparticles were assayed for inhibition of some CA transmembrane isoforms (CA IX and XII) as well as of two cytosolic isoforms (CA I and II), and show interesting inhibitory efficiency in the submicromolar range and some selectivity for transmembrane isoforms