Lockheed Martin Energy Systems Research Articles

Gelcasting of non-oxide ceramic powders with reactive surfaces: M.S.Morrow et al. (Lockheed Martin Energy Systems, USA.)

Gelcasting of non-oxide ceramic powders with reactive surfaces: M.S.Morrow et al. (Lockheed Martin Energy Systems, USA.)

URANIUM EXTRACTION SELECTIVITIES OF DIBUTYL CARBITOL AND TRIBUTYL PHOSPHATE IN THE SYSTEM UO2(NO3)2-HNO3H2O-Al(NO3)3-SOLVENT*

ABSTRACT Historically, both the BUTEX (dibutyl carbitol-based) and PUREX (tributyl phosphate-based) processes have been used for uranium recovery and purification. Currently, BUTEX- and PUREX-type extraction processes are being used in series for recovery of isotopically enriched uranium at the Oak Ridge Y-12 Plant. The use of two solvents is predicated on the differing selectivities of each with regard to the contaminant elements present in the uranium source stream. As part of efforts to streamline plant operations in response to decreasing throughput requirements, the Y-12 Development Division is evaluating options for converting the existing two-solvent operation to a single-solvent process. At the request of the Y-12 Development Division, the Robotics and Process Division at the Oak Ridge National Laboratory has undertaken evaluation of solvents for use in a single-solvent recovery process. Initial efforts have been directed toward development of a single-solvent, dibutyl carbitol-or tributyl phosphate-based process that produces a product with purity equal to or exceeding what is currently obtained in the two-cycle, two-solvent operation. The test effort has involved both laboratory equilibrium determinations and engineering-scale process demonstrations in multistage flowsheets using centrifugal solvent extraction contactors. Excellent uranium recovery results have been obtained from both dibutyl carbitol- and tributyl phosphate-based solvent extraction flowsheets. Contaminant rejection performance by the two solvents is similar for many of the elements considered. Extraction of some contaminant elements by tributyl phosphate is significant enough to conclude that the solvent is not as selective for uranium as is dibutyl carbitol. This determination does not necessarily eliminate tributyl phosphate from consideration for use in a single-solvent process but does indicate a need for effective scrubbing of contaminants from uranium-loaded tributyl phosphate, possibly by partial reflux of the purified, aqueous uranyl nitrate product solution. *Research sponsored by the Oak Ridge Y-12 Development Division for the U.S. Department of Energy under Contract No. DE-AC05-96OR22464 with Lockheed Martin Energy Systems. ** Managed by Lockheed Martin Energy Research Corp. for the U.S. Department of Energy.

5666821 Method for producting pellets for use in a cryoblasting process: Foster Christopher; Fisher Paul W Clinton, TN, United States assigned to Lockheed Martin Energy Systems Inc

Los marcadores de inflamación son reactantes de fase aguda que se elevan en procesos inflamatorios como la isquemia crítica del miembro inferior (ICMI). La proteína C reactiva de alta sensibilidad (PCR-hs) ha sido el más utilizado para predecir eventos cardiovasculares en pacientes con ateroesclerosis. El objetivo de este estudio es conocer el valor pronóstico de la PCR-hs preoperatoria en pacientes con ICMI tratados mediante revascularización.Estudio prospectivo de 100 pacientes con ICMI, incluidos de forma consecutiva y tratados mediante revascularización. En todos se realizó PCR-hs previa al procedimiento. La evaluación durante el año siguiente incluyó: mortalidad, eventos cardiovasculares (coronarios, neurológicos y en miembros inferiores) y restenosis arterial ecográfica.Se intervinieron 100 pacientes, 67 varones y 33 mujeres, con mediana de 76 años (rango intercuartílico [RIC] 65–83). Las categorías Rutherford eran: 4 (n = 29), 5 (n = 63) y 6 (n = 8). La mediana de la PCR-hs era 1,5 mg/dl (RIC 0,5–3). El índice tobillo-brazo preoperatorio era 0,3 (RIC 0,19–0,45). Las modalidades de tratamiento fueron: endovascular (n = 45), quirúrgico (n = 43) e híbrido (n = 12). No hubo mortalidad perioperatoria. El seguimiento fue de 11,7 meses (RIC 9,3–13,6). Fallecieron 20 pacientes y ocurrieron 90 eventos cardiovasculares en 70 pacientes. Se detectaron restenosis ecográfica > 70 % y/u obstrucción arterial en 39 pacientes. Había mayor probabilidad de mortalidad al año cuando la PCR-hs preoperatoria era > 3 mg/dl (p = 0,022; odds ratio [OR] = 6,15; intervalo de confianza [IC] 95 % 1,30–29,14).Valores elevados de PCR-hs (> 3 mg/dl) en el preoperatorio de pacientes con ICMI se relacionan con una mayor mortalidad al año.Acute-phase reactants are inflammatory markers that increase during inflammatory events such as critical limb ischaemia (CLI). High-sensitivity C-reactive protein (hsCRP) is the most useful marker to predict cardiovascular events in patients with atherosclerosis. We investigated whether baseline levels of hsCRP predict mid-term clinical outcome in patients with CLI.We prospectively studied 100 consecutive patients with CLI who were treated by revascularization. All the patients had hsCRP samples taken prior to the intervention. During the first year the following endpoints were evaluated: mortality, cardiovascular events (coronary, neurological and lower limb) and echographic restenosis.A total of 100 patients were intervened (67 males and 33 females). The median age was 76 years (interquartile range [IQR] 65-83). Rutherford categories were: 4 (n = 29), 5 (n = 63) and 6 (n = 8). The median preoperative hsCRP was 1.5 mg/dl (IQR 0.5–3). Baseline ankle-braquial index was 0.3 (IQR 0.19–0.45). Treatment modalities were: endovascular (n = 45), surgical (n = 43) and hybrid (n = 12). There was no perioperative mortality. Median follow-up was 11.7 months (IQR 9.3–13.6). During the first year, 20 patients died and there were 90 cardiovascular events in 70 patients. There were 39 patients with echographic restenosis > 70 % or obstruction. There was a higher probability of death when preoperative hsCRP was > 3 mg/dl (p = 0.022; odds ratio [OR] = 6.15; 95 % confidence interval [CI] 1.30–29.14).CLI patients with preoperative values of PCR-hs > 3 mg/dl are associated with death during the first year after treatment.

Medical Management of Occupational and Non-Occupational Conditions

Presenting Author: Daniel E. Conrad, MD; Corporate Medical Director; Lockheed-Martin Energy Systems, Inc.; Oak Ridge, TN

Economic Growth and Sustainability: A New Challenge

We have the greatest respect for the authors of the Science article (Arrow et al. 1995) and we agree with their arguments. However, we would like to offer some points of clarification and to broaden the base of the discussion. The Science article focused on the inverted U relationship between environmental quality and gross domestic product (GDP). But this empirical relationship adopts a trivial definition of environmental quality: emissions of specific pollutants, compared across vast differences in culture, resources, and scales. A subset of pollutants in a limited number of places cannot be accepted as surrogates for the complex interactions between economic growth and the environment on which that growth depends. Policy discussions and scientific debates often focus on a simplified concept of environmental interactions. Accepting these simple concepts places advocates of growth in a strong position to argue for continued development. At one extreme, the environment is reduced to extractable resources. The environmentalist argues that economic growth will exhaust extractable resources, such as, oil and iron ore. This argument faces a forceful counterargument: most extractable resources are substitutable. Substitutes may be other extractables, human capital, or human-made capital. Don't worry about running out of coal-there is fission, fusion, or biomass fuel crops. The point can be argued, of course, because substitutability varies widely across extractable resources and experience has shown that substitutes, such as nuclear power, may create as many problems as they solve. But if one accepts that the environmental problem can be reduced to extractable resources, the advocates of growth start the debate from a strong position. At another extreme, environmental issues are reduced to amenities-nice places to have a picnic. In this case, the environment has aesthetic value but no direct involvement in the economic process. You are unlikely to win the argument if you maintain that aesthetics are more important than jobs. If you want to preserve Spotted Owls simply because they are pretty, you are likely to be hit in the back of the head with an axe handle. In other cases, analysis focuses on direct physical and health effects of pollution. For example, the assessment of acid precipitation considered direct damage to buildings, agricultural crops, visibility, and trout populations. But eliminating direct impacts of pollutants will not prevent gradual, indirect effects such as climate change or loss of the ozone layer. Underlying all of these simplifications are basic ecosystem services: cleaning the water, purifying the air, decomposing wastes, maintaining CO2 balance, permitting recovery from natural disturbances, filtering ultraviolet radiation, and providing sources of new medicines. These ecosystem functions are not substitutable and not just amenities that can be traded for short-term economic gains. Discussions of economic growth often ASSUME stable, resilient ecosystems that will continue to provide these life-support services. But economic development will impose increasing stress on ecosystems, even if wealthy nations can be expected I Manuscript received 10 July 1995. 2 For reprints of this Forum, see footnote 1, p. 12. 3 The Oak Ridge National Laboratory is managed by Lockheed Martin Energy Systems, Inc., under subcontract number DE-AC05-840R21400 for the U.S. Department of Energy. Environmental Sciences Division Publication Number 4454.