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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Oxygen stoichiometry control of nanometric oxide compounds: The case of titanium ferrites

Three techniques have been coupled with an original device, based on H{sub 2}/H{sub 2}O equilibrium, controlling oxygen partial pressure: XRD, TGA and DC conductivity in order to characterize very reactive compounds such as nanometric powders. From XRD, both the structure and the oxygen stoichiometry (thanks to their lattice parameter) were investigated in situ. From TGA, it was the oxygen stoichiometry (thanks to mass gain or loss) which was determined. From DC conductivity, it was both the structure and the oxygen stoichiometry (thanks to the activation energy) which were obtained. The advantages were to determine very rapidly and with a small amount of powder the equilibrium conditions (T, pO{sub 2}) necessary to obtain the desired phase and stoichiometry. These methods have been evaluated for nanometric titanium ferrites. Two phenomena have been observed during the reducing process: the precipitation of a rhombohedral phase and a significant grain growth linked together. - Graphical abstract: XRD patterns of Fe{sub 3(1-{delta})}O{sub 4} nanometric powders obtained in situ during a reducing treatment. The stoichiometric compound was obtained by a thermal annealing at 460 deg. C under pO{sub 2}=3x10{sup -26} Pa ({Phi}{sub DRX}=100 nm). In inset, data of the experimental lattice parameter compared to the theoretical one. {alpha} represents the rhomboedrical phase which precipitates during this thermal treatment, then disappeared. Highlights: > The control of the deviation from oxygen stoichiometry is rarely consider in literature. > At the nanometric scale, it is necessary to develop synthesis routes under appropriate atmosphere. > These synthesis must be coupled with in situ characterization tools. > It opens the door to fast and precise studies concerning the evolution of nanometric materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Design and operational considerations of catalytic membrane reactors for ammonia synthesis

Production of ammonia using hydrogen derived from renewable electricity instead of hydrocarbon reforming would dramatically reduce the carbon footprint of this commodity chemical. Novel technologies such as catalytic membrane reactors may potentially be more compatible with distributed ammonia production than the conventional Haber-Bosch process. Here, a reactor model is developed based on integrating a standard industrial iron catalyst into a catalytic membrane reactor (CMR) equipped with an inorganic membrane that is selective to NH 3 over N 2 /H 2 . CMR performance is studied as functions of wide ranges of membrane properties and operating conditions. Conversion and ammonia recovery are dictated principally by the ammonia permeance, and the benefits by using membranes become significant above 100 GPU = 3.4 × 10 –8 mol m –2 s –1 Pa –1 . To be effective, the CMR requires a minimum selectivity for ammonia of 10 over both nitrogen and hydrogen, and purity scales with the effective selectivity. Increasing the pressure of operation significantly improves all metrics, and at P = 30 bar with a quality membrane ammonia is almost completely recovered, enabling direct recycle of un-reacted hydrogen and nitrogen without need for recompression. Temperature drives conversion and scales monotonically without thermodynamic limitations in a CMR. Alternatively, the temperature may be reduced as low as 300°C while achieving conversion levels surpassing equilibrium limits at T = 400°C in a conventional reactor.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Assessment of biotechnological strategies for the valorization of metal bearing wastes

Highlights: Black-Right-Pointing-Pointer We examine biological strategies to valorize different metal rich solid waste. Black-Right-Pointing-Pointer Bacteria play a key role in the mobilization of Zn and Y from fluorescent powders. Black-Right-Pointing-Pointer Ferrous iron is crucial for the bioleaching of Ni, V, Mo from spent catalysts. Black-Right-Pointing-Pointer No biological effect is observed for Ni, Zn, As, Cr mobilisation from sediments. - Abstract: The present work deals with the application of biotechnology for the mobilization of metals from different solid wastes: end of life industrial catalysts, heavy metal contaminated marine sediments and fluorescent powders coming from a cathode ray tube glass recycling process. Performed experiments were aimed at assessing the performance of acidophilic chemoautotrophic Fe/S-oxidizing bacteria for such different solid matrices, also focusing on the effect of solid concentration and of different substrata. The achieved results have evidenced that metal solubilization seems to be strongly influenced by the metal speciation and partitioning in the solid matrix. No biological effect was observed for Ni, Zn, As, Cr mobilization from marine sediments (34%, 44%, 15%, 10% yields, respectively) due to metal partitioning. On the other hand, for spent refinery catalysts (Ni, V, Mo extractions of 83%, 90% and 40%, respectively) and fluorescent powders (Zn and Y extraction of 55% and 70%, respectively), the improvement in metal extraction observed in the presence of a microbial activity confirms the key role of Fe/S oxidizing bacteria and ferrous iron. A negative effect of solid concentration was in general observed on bioleaching performances, due to the toxicity of dissolved metals and/or to the solid organic component.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2010

Reanalysis of the (J=5) state at 592 keV in {sup 180}Ta and its role in the {nu}-process nucleosynthesis of {sup 180}Ta in supernovae

We analyze the production and freeze-out of the isomer {sup 180}Ta{sup m} in the {nu}-process. We consider the influence of a possible low-lying intermediate (J=5) state at 592 keV using a transition width estimated from the measured half-life. This more realistic width is much smaller than the previous estimate. We find that the 592-keV state leads only to a small reduction of the residual isomer population ratio from the previous result; that is, considering this better estimate for the transition width, the isomer population ratio changes from R=0.39 to R=0.38, whereas previously it was estimated that this transition could reduce the ratio to R=0.18. This finding strengthens the evidence that {sup 138}La and {sup 180}Ta are coproduced by neutrino nucleosynthesis with an electron neutrino temperature of kT{approx_equal}4 MeV.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

The enhanced value of combining conventional and 'omics' analyses in early assessment of drug-induced hepatobiliary injury

The InnoMed PredTox consortium was formed to evaluate whether conventional preclinical safety assessment can be significantly enhanced by incorporation of molecular profiling ('omics') technologies. In short-term toxicological studies in rats, transcriptomics, proteomics and metabolomics data were collected and analyzed in relation to routine clinical chemistry and histopathology. Four of the sixteen hepato- and/or nephrotoxicants given to rats for 1, 3, or 14 days at two dose levels induced similar histopathological effects. These were characterized by bile duct necrosis and hyperplasia and/or increased bilirubin and cholestasis, in addition to hepatocyte necrosis and regeneration, hepatocyte hypertrophy, and hepatic inflammation. Combined analysis of liver transcriptomics data from these studies revealed common gene expression changes which allowed the development of a potential sequence of events on a mechanistic level in accordance with classical endpoint observations. This included genes implicated in early stress responses, regenerative processes, inflammation with inflammatory cell immigration, fibrotic processes, and cholestasis encompassing deregulation of certain membrane transporters. Furthermore, a preliminary classification analysis using transcriptomics data suggested that prediction of cholestasis may be possible based on gene expression changes seen at earlier time-points. Targeted bile acid analysis, based on LC-MS metabonomics data demonstrating increased levels of conjugated or unconjugated bile acids in response to individual compounds, did not provide earlier detection of toxicity as compared to conventional parameters, but may allow distinction of different types of hepatobiliary toxicity. Overall, liver transcriptomics data delivered mechanistic and molecular details in addition to the classical endpoint observations which were further enhanced by targeted bile acid analysis using LC/MS metabonomics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl{sub 2} or CaSO{sub 4}, which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl{sub 2} exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect on mechanical strength was also observed when CaSO{sub 4} was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Valorization of pellets from municipal WWTP sludge in lightweight clay ceramics

A direct result of the growing number of municipal wastewater-treatment plants (WWTPs) has been an increase in the generation of large amounts of sewage sludge that requires environmentally acceptable final destination. To decrease the volume of sludge, a common technique is drying the sludge at a low temperature in rotary kilns. The result of this process is a granulated material consisting of dehydrated sludge pellets. After this treatment, this pelletized material becomes easier to manipulate, but it also becomes a more toxic waste, containing dangerous substances, mostly of the lipid type. At its final stage, this material is usually incinerated, used as a comburent material, used as an agricultural fertilizer, or used in the cement industry. Each application has its own problems and requires remediation measures from the safety and environmental viewpoints. In this study, we looked beyond these possible applications and analyzed the transformation of sewage sludge through a ceramization process into a material similar to expanded clays; we subsequently explored its uses in the building industry or in the agriculture industry, among others. Both the properties of the product material and the production method were characterized, and an environmental analysis was conducted. The new, lightweight material had a microstructure with open porosity and low thermal conductivity. Environmental characterization such as the leaching test revealed that undetectable amounts of hazardous metals from the sludge were present in the leachate after the sludge went through a thermal treatment, despite their initial presence (with the exception of vanadium, which could pose some restrictions on some of the proposed uses for the final product). Toxicity tests also showed negative results. The study of gaseous emissions during production revealed emissions factors similar to those during the production of conventional clay ceramics, although with higher organic emissions. As for conventional clay ceramics, industrial production would require the implementation of some type of air-depuration system. The results showed that the ceramization of sludge pellets is a promising valorization technique worth considering from both the economic and technological perspectives.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Experimental Investigations on Pulsed Nd:YAG Laser Welding of C17300 Copper-Beryllium and 49Ni-Fe Soft Magnetic Alloys

Copper-beryllium and soft magnetic alloys must be joined in electrical and electro-mechanical applications. There is a high difference in melting temperatures of these alloys which cause to make the joining process very difficult. In addition, copper-beryllium alloys are of age hardenable alloys and precipitations can brittle the weld. 49Ni-Fe alloy is very hot crack sensitive. Moreover, these alloys have different heat transfer coefficients and reflection of laser beam in laser welding process. Therefore, the control of welding parameters on the formation of adequate weld puddle composition is very difficult. Laser welding is an advanced technique for joining of dissimilar materials since it can precisely control and adjust the welding parameters. In this study, a 100W Nd:YAG pulsed laser machine was used for joining 49Ni-Fe soft magnetic to C17300 copper-beryllium alloys. Welding of samples was carried out autogenously by changing the pulse duration, diameter of beam, welding speed, voltage and frequency. The spacing between samples was set to almost zero. The ample were butt welded. It was required to apply high voltage in this study due to high reflection coefficient of copper alloys. Metallography, SEM analysis, XRD and microhardness measurement was used for survey of results. The results show that the weld strength depends upon the chemical composition of the joints. To change the wells composition and heat input of the welds, it was attempted to deviate the laser focus away from the weld centerline. The best strength was achieved by deviation of the laser beam away about 0.1mm from the weld centerline. The result shows no intermetallic compounds if the laser beam is deviated away from the joint.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Scientific Solutions to Nuclear Waste Environmental Challenges

The Hidden Cost of Nuclear Weapons The Cold War arms race drove an intense plutonium production program in the U.S. This campaign produced approximately 100 tons of plutonium over 40 years. The epicenter of plutonium production in the United States was the Hanford site, a 586 square mile reservation owned by the Department of Energy and located on the Colombia River in Southeastern Washington. Plutonium synthesis relied on nuclear reactors to convert uranium to plutonium within the reactor fuel rods. After a sufficient amount of conversion occurred, the rods were removed from the reactor and allowed to cool. They were then dissolved in an acid bath and chemically processed to separate and purify plutonium from the rest of the constituents in the used reactor fuel. The acidic waste was then neutralized using sodium hydroxide and the resulting mixture of liquids and precipitates (small insoluble particles) was stored in huge underground waste tanks. The byproducts of the U.S. plutonium production campaign include over 53 million gallons of high-level radioactive waste stored in 177 large underground tanks at Hanford and another 34 million gallons stored at the Savannah River Site in South Carolina. This legacy nuclear waste represents one of the largest environmental clean-up challenges facing the world today. The nuclear waste in the Hanford tanks is a mixture of liquids and precipitates that have settled into sludge. Some of these tanks are now over 60 years old and a small number of them are leaking radioactive waste into the ground and contaminating the environment. The solution to this nuclear waste challenge is to convert the mixture of solids and liquids into a durable material that won't disperse into the environment and create hazards to the biosphere. What makes this difficult is the fact that the radioactive half-lives of some of the radionuclides in the waste are thousands to millions of years long. (The half-life of a radioactive substance is the amount of time it takes for one-half of the material to undergo radioactive decay.) In general, the ideal material would need to be durable for approximately 10 half-lives to allow the activity to decay to negligible levels. However, the potential health effects of each radionuclide vary depending on what type of radiation is emitted, the energy of that emission, and the susceptibility for the human body to accumulate and concentrate that particular element. Consequently, actual standards tend to be based on limiting the dose (energy deposited per unit mass) that is introduced into the environment. The Environmental Protection Agency (EPA) has the responsibility to establish standards for nuclear waste disposal to protect the health and safety of the public. For example, the Energy Policy Act of 1992 directed the EPA to establish radiation protection standards for the Yucca Mountain geologic repository for nuclear wastes. The standards for Yucca Mountain were promulgated in 2008, and limit the dose to 15 millirem per year for the first 10,000 years, and 100 milirem per year between 10,000 years and 1 million years (40 CFR Part 197; http://www.epa.gov/radiation/yucca/2008factsheet.html). So, the challenge is two-fold: (1) develop a material (a waste form) that is capable of immobilizing the waste over geologic time scales, and (2) develop a process to convert the radioactive sludge in the tanks into this durable waste form material. Glass: Hard, durable, inert, and with infinite chemical versatility Molten glass is a powerful solvent liquid, which can be designed to dissolve almost anything. When solidified, it can be one of the most chemically inert substances known to man. Nature's most famous analogue to glass is obsidian, a vitreous product of volcanic activity; formations over 17 million years old have been found. Archaeologists have found man-made glass specimens that are five thousand years old.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Study of carbon dioxide adsorption on a Cu-nitroprusside polymorph

A careful structural characterization was carried out to unequivocally determine the structure of the synthesized material. The TGA, DRIFTS and a Pawley fitting of the XRD powder profiles indicate that the hydrated and in situ dehydrated polymorph crystallizes in the orthorhombic space group Pnma. Meanwhile, the CO{sub 2} isosteric heat of adsorption appears to be independent of loading with an average value of 30 kJ/mol. This translates to a physisorption type interaction, where the adsorption energy corresponding to wall and lateral interactions are mutually compensated to produce, an apparently, homogeneous adsorption energy. The somewhat high adsorption energy is probably due to the confinement of the CO{sub 2} molecules in the nitroprusside pores. Statistical Physics and the Dubinin theory for pore volume filling allowed model the CO{sub 2} equilibrium adsorption process in Cu-nitroprusside. A DRIFTS test for the adsorbed CO{sub 2} displayed a peak at about 2338 cm{sup -1} that was assigned to a contribution due to physical adsorption of the molecule. Another peak found at 2362 cm{sup -1} evidenced that this molecule interacts with the Cu{sup 2+}, which appears to act as an electron accepting Lewis acid site. The aim of the present paper is to report a Pnma stable Cu-nitroprusside polymorph obtained by the precipitation method that can adsorb carbon dioxide. -- Graphical abstract: The adsorption space of a very well characterized Cu-nitroprusside polymorph, applying carbon dioxide as probe molecule, was studied. Display Omitted Highlights: {yields} Accurate information about the geometry of the adsorption space was provided. {yields} Truthful data about the interactions within the adsorption space was presented. {yields} The structure of the tested Cu-NP polymorph was established. {yields} Was evidenced adsorbed CO{sub 2} molecules in the form of weakly bonded adducts. {yields} Is proposed that adsorbed molecules could change the Cu-NP magnetic properties.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO{sub 2} pressure

Highlights: > Accelerated carbonation studied to improve environmental properties of steel slag. > Carbonation found to occur predominantly at surface of the steel slag grains. > Combined geochemical modelling and mineral analysis revealed controlling processes. > Enhanced V-leaching with di-Ca silicate (C2S) dissolution identified as major source. > Identified mineral transformations provide guidance for further quality improvement. - Abstract: Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO{sub 2} pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 {sup o}C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO{sub 2} and the resulting pH reduction occurred within 24 h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted. The pH of the K3 slag (originally pH {+-} 12.5) was reduced by about 1.5 units, while the K1 slag showed a smaller decrease in pH from about 11.7 to 11.1. However, the pH reduction after carbonation of the K3 slag was observed to lead to an increased V-leaching. Vanadium leaching from the K1 slag resulted in levels above the limit values of the Dutch Soil Quality Decree, for both the untreated and carbonated slag. V-leaching from the carbonated K3 slag remained below these limit values at the relatively high pH that remained after carbonation. The V-bearing di-Ca silicate (C2S) phase has been identified as the major source of the V-leaching. It is shown that the dissolution of this mineral is limited in fresh steel slag, but strongly enhanced by carbonation, which causes the observed enhanced release of V from the K3 slag. The obtained insights in the mineral transformation reactions and their effect on pH and V-leaching provide guidance for further improvement of an accelerated carbonation technology.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2010

USE OF CEMENTITIOUS MATERIALS FOR SRS REACTOR FACILITY IN-SITU DECOMMISSIONING - 11620

The United States Department of Energy (US DOE) concept for facility in-situ decommissioning (ISD) is to physically stabilize and isolate in tact, structurally sound facilities that are no longer needed for their original purpose of, i.e., producing (reactor facilities), processing (isotope separation facilities) or storing radioactive materials. The Savannah River Site 105-P and 105-R Reactor Facility ISD requires about 250,000 cubic yards of grout to fill the below grade structure. The fills are designed to prevent subsidence, reduce water infiltration, and isolate contaminated materials. This work is being performed as a Comprehensive Environmental Response, Compensations and Liability Act (CERCLA) action and is part of the overall soil and groundwater completion projects for P- and R-Areas. Cementitious materials were designed for the following applications: (1) Below grade massive voids/rooms: Portland cement-based structural flowable fills for - Bulk filling, Restricted placement and Underwater placement. (2) Special below grade applications for reduced load bearing capacity needs: Cellular portland cement lightweight fill (3) Reactor vessel fills that are compatible with reactive metal (aluminum metal) components in the reactor vessels: Calcium sulfoaluminate flowable fill, and Magnesium potassium phosphate flowable fill. (4) Caps to prevent water infiltration and intrusion into areas with the highest levels of radionuclides: Portland cement based shrinkage compensating concrete. A system engineering approach was used to identify functions and requirements of the fill and capping materials. Laboratory testing was performed to identify candidate formulations and develop final design mixes. Scale-up testing was performed to verify material production and placement as well as fresh and cured properties. The 105-P and 105-R ISD projects are currently in progress and are expected to be complete in 2012. The focus of this paper is to describe the (1) grout mixes for filling the reactor vessels, and (2) a specialty grout mix to fill a selected portion of the P-Reactor Disassembly Basin. Details of the grout mixes designed for ISD of he SRS Reactor Disassembly Basins and below grade portions of the 105-Buildings was described elsewhere. Material property test results, placement strategies, full-scale production and delivery systems will also be described.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2010

TRENDS IN {sup 44}Ti AND {sup 56}Ni FROM CORE-COLLAPSE SUPERNOVAE

We compare the yields of {sup 44}Ti and {sup 56}Ni produced from post-processing the thermodynamic trajectories from three different core-collapse models-a Cassiopeia A progenitor, a double shock hypernova progenitor, and a rotating two-dimensional explosion-with the yields from exponential and power-law trajectories. The peak temperatures and densities achieved in these core-collapse models span several of the distinct nucleosynthesis regions we identify, resulting in different trends in the {sup 44}Ti and {sup 56}Ni yields for different mass elements. The {sup 44}Ti and {sup 56}Ni mass fraction profiles from the exponential and power-law profiles generally explain the tendencies of the post-processed yields, depending on which regions are traversed by the model. We find that integrated yields of {sup 44}Ti and {sup 56}Ni from the exponential and power-law trajectories are generally within a factor two or less of the post-process yields. We also analyze the influence of specific nuclear reactions on the {sup 44}Ti and {sup 56}Ni abundance evolution. Reactions that affect all yields globally are the 3{alpha}, p(e{sup -}, {nu}{sub e})n and n(e{sup +},{nu}-bar{sub e})p. The rest of the reactions are ranked according to their degree of impact on the synthesis of {sup 44}Ti. The primary ones include {sup 44}Ti({alpha}, p){sup 47}V, {sup 40}Ca({alpha}, {gamma}){sup 44}Ti, {sup 45}V(p, {gamma}){sup 46}Cr, {sup 40}Ca({alpha}, p){sup 43}Sc, {sup 17}F({alpha}, p){sup 20}Ne, {sup 21}Na({alpha}, p){sup 24}Mg, {sup 41}Sc(p, {gamma}){sup 42}Ti, {sup 43}Sc(p, {gamma}){sup 44}Ti, {sup 44}Ti(p, {gamma}){sup 45}V, and {sup 57}Ni(p, {gamma}){sup 58}Cu, along with numerous weak reactions. Our analysis suggests that not all {sup 44}Ti need to be produced in an {alpha}-rich freeze-out in core-collapse events, and that reaction rate equilibria in combination with timescale effects for the expansion profile may account for the paucity of {sup 44}Ti observed in supernova remnants.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Positive effect of Sc and Zr on globular microstructure formation in AA7075 thixoforming feedstock

One of methods of obtaining a fine globular microstructure in a semi-solid range, necessary for thixoforming process, is modifiers additions. For this purpose 0.5 weight percent of modifying elements-scandium and zirconium-was added to 7075 alloy. The microstructure of such alloy consisted of homogeneously distributed globular grains of solid solution with the following chemical composition: Mg - 1.9%, Al - 91.6%, Cu - 1.0%, Zn - 5.5%(all in wt.%). Quantitative metallographic analysis showed that the average grain size was 23.5 {mu}m, much smaller than in the alloy without additions and 3.08% volume fraction of precipitates in the form of a layer between spherical {alpha}(Al) grains. X-ray phase analysis of the 7075 alloy with Sc and Zr additions confirmed the dominant presence of aluminum solid solution and the intermetallic hexagonal phase MgZn{sub 2}. Electron diffraction pattern confirmed location of {eta}MgZn{sub 2} phase at the grain boundaries. EDS chemical analysis of the {eta}MgZn{sub 2} phase showed following content of elements: Mg - 17.2%, Al - 20.4%, Cu - 27.8%, Zn - 34.6%. The larger amount of Cu and Al indicated non-stoichiometry of the {eta} phase, which can be presented with a formula [Mg(Zn,Al,Cu){sub 2}]. Additionally, inside the aluminum solution, small, square-shaped precipitations enriched with Sc and Zr were observed. Electron diffraction pattern allowed identification of the precipitates as cubic Al{sub 3}(Sc,Zr) phase. The average hardness of feedstock was 105 HV5. DSC analysis during heating of the alloy enabled the estimation of a solidus line, at temperature of 548 deg. C and a liquidus line at temperature: 656 deg. C. For cooling, the temperatures for solidus and liquidus were 545 deg. C and 636 deg. C respectively. Additionally, the relation of liquid phase as a function of temperature was determined. Measurements of rheological properties in the semi-solid range, using the Searl system indicated that an increase of a particle size leads to an observable decrease of viscosity during isothermal shearing.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash

Highlights: Black-Right-Pointing-Pointer Incinerator fly ash (IFA) is added to an alkali activated coal fly ash (CFA) matrix. Black-Right-Pointing-Pointer Means of stabilizing the incinerator ash for use in construction applications. Black-Right-Pointing-Pointer Concrete made from IFA, CFA and IFA-CFA mixes was chemically characterized. Black-Right-Pointing-Pointer Environmentally friendly solution to IFA disposal by reducing its toxicity levels. - Abstract: Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5.00 mg/L, respectively.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2010

Kick processes in the merger of two colliding black holes

We examine numerically the process of momentum extraction by gravitational waves in the merger of two colliding black holes, in the realm of Robinson-Trautman spacetimes. The initial data have already a common horizon so that the evolution covers the post-merger phase up to the final configuration of the remnant black hole. The analysis of the momentum flux carried out by gravitational waves indicates that two distinct regimes are present in the post-merger phase: (i) an initial accelerated regime, followed by (ii) a deceleration regime in which the deceleration increases rapidly towards a maximum and then decreases to zero, when the gravitational wave emission ceases. The analysis is based on the Bondi-Sachs conservation law for the total momentum of the system. We obtain the total kick velocity V{sub k} imparted on the merged black hole during the accelerated regime (i) and the total antikick velocity V{sub ak} during the decelerated regime (ii), by evaluating the impulse of the gravitational wave flux during both regimes. The distributions of both V{sub k} and V{sub ak} as a function of the symmetric mass ratio {eta} satisfy a simple {eta}-scaling law motivated by post-Newtonian analytical estimates. In the {eta}-scaling formula the Newtonian factor is dominant in the decelerated regime, that generates V{sub ak}, contrary to the behavior in the initial accelerated regime. For an initial infalling velocity v/c{approx_equal}0.462 of each individual black hole we obtain a maximum kick V{sub k{approx_equal}}6.4 km/s at {eta}{approx_equal}0.209, and a maximum antikick V{sub ak{approx_equal}}109 km/s at {eta}{approx_equal}0.205. The net antikick velocity (V{sub ak}-V{sub k}) also satisfies a similar {eta}-scaling law with a maximum approximately 102 km/s also at {eta}{approx_equal}0.205, qualitatively consistent with results from numerical relativity simulations, and post-Newtonian evaluations of binary black hole inspirals. For larger values of the initial data parameter v/c substantial larger values of the net antikick velocity are obtained. Based on the several velocity variables obtained, we discuss a possible definition of the center-of-mass motion of the merged system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

High rate mesophilic, thermophilic, and temperature phased anaerobic digestion of waste activated sludge: A pilot scale study

Highlights: Black-Right-Pointing-Pointer High temperatures were tested in single and two-stage anaerobic digestion of waste activated sludge. Black-Right-Pointing-Pointer The increased temperature demonstrated the possibility of improving typical yields of the conventional mesophilic process. Black-Right-Pointing-Pointer The temperature phased anaerobic digestion process (65 + 55 Degree-Sign C) showed the best performances with yields of 0.49 m{sup 3}/kgVS{sub fed}. Black-Right-Pointing-Pointer Ammonia and phosphate released from solids destruction determined the precipitation of struvite in the reactor. - Abstract: The paper reports the findings of a two-year pilot scale experimental trial for the mesophilic (35 Degree-Sign C), thermophilic (55 Degree-Sign C) and temperature phased (65 + 55 Degree-Sign C) anaerobic digestion of waste activated sludge. During the mesophilic and thermophilic runs, the reactor operated at an organic loading rate of 2.2 kgVS/m{sup 3}d and a hydraulic retention time of 20 days. In the temperature phased run, the first reactor operated at an organic loading rate of 15 kgVS/m{sup 3}d and a hydraulic retention time of 2 days while the second reactor operated at an organic loading rate of 2.2 kgVS/m{sup 3}d and a hydraulic retention time of 18 days (20 days for the whole temperature phased system). The performance of the reactor improved with increases in temperature. The COD removal increased from 35% in mesophilic conditions, to 45% in thermophilic conditions, and 55% in the two stage temperature phased system. As a consequence, the specific biogas production increased from 0.33 to 0.45 and to 0.49 m{sup 3}/kgVS{sub fed} at 35, 55, and 65 + 55 Degree-Sign C, respectively. The extreme thermophilic reactor working at 65 Degree-Sign C showed a high hydrolytic capability and a specific yield of 0.33 gCOD (soluble) per gVS{sub fed}. The effluent of the extreme thermophilic reactor showed an average concentration of soluble COD and volatile fatty acids of 20 and 9 g/l, respectively. Acetic and propionic acids were the main compounds found in the acids mixture. Because of the improved digestion efficiency, organic nitrogen and phosphorus were solubilised in the bulk. Their concentration, however, did not increase as expected because of the formation of salts of hydroxyapatite and struvite inside the reactor.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2026

Open quantum system approach to inclusive jet production in heavy-ion collisions

We derive a factorization formula for inclusive jet production in heavy-ion collisions using the tools of Effective Field Theory (EFT). We show how physics at widely separated scales in this process can be systematically separated by matching to EFTs at successively lower virtualities. Owing to a strong scale separation, we recover a vacuum-like DGLAP evolution above the jet scale, while the additional low-energy scales induced by the medium effectively probe the internal structure of the jet. As a result, the cross section can be written as a series with an increasing number of subjets characterized by perturbative matching coefficients each of which is convolved with a distinct function. These functions encode broadening, medium-induced radiations as well as quantum interference such as the Landau-Pomeranchuk-Migdal effect and color coherence dynamics to all orders in perturbation theory. As a first application of this EFT framework, we investigate the case of an unresolved jet and show how the cross section can be factorized and fully separate the jet dynamics from the universal physics of the medium. To compare to the existing literature, we explicitly compute the medium jet function at next-to-leading order in the coupling and leading order in medium opacity.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗