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Sample records for formation confers aluminum

  1. A Formate Dehydrogenase Confers Tolerance to Aluminum and Low pH1[OPEN

    PubMed Central

    Gong, Yu Long; Fan, Wei; Xu, Jia Meng; Liu, Yu; Cao, Meng Jie; Wang, Ming-Hu

    2016-01-01

    Formate dehydrogenase (FDH) is involved in various higher plant abiotic stress responses. Here, we investigated the role of rice bean (Vigna umbellata) VuFDH in Al and low pH (H+) tolerance. Screening of various potential substrates for the VuFDH protein demonstrated that it functions as a formate dehydrogenase. Quantitative reverse transcription-PCR and histochemical analysis showed that the expression of VuFDH is induced in rice bean root tips by Al or H+ stresses. Fluorescence microscopic observation of VuFDH-GFP in transgenic Arabidopsis plants indicated that VuFDH is localized in the mitochondria. Accumulation of formate is induced by Al and H+ stress in rice bean root tips, and exogenous application of formate increases internal formate content that results in the inhibition of root elongation and induction of VuFDH expression, suggesting that formate accumulation is involved in both H+- and Al-induced root growth inhibition. Over-expression of VuFDH in tobacco (Nicotiana tabacum) results in decreased sensitivity to Al and H+ stress due to less production of formate in the transgenic tobacco lines under Al and H+ stresses. Moreover, NtMATE and NtALS3 expression showed no changes versus wild type in these over-expression lines, suggesting that herein known Al-resistant mechanisms are not involved. Thus, the increased Al tolerance of VuFDH over-expression lines is likely attributable to their decreased Al-induced formate production. Taken together, our findings advance understanding of higher plant Al toxicity mechanisms, and suggest a possible new route toward the improvement of plant performance in acidic soils, where Al toxicity and H+ stress coexist. PMID:27021188

  2. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bott, June H.

    Transformation-induced plasticity (TRIP) steels containing higher amounts of aluminum than conventional steels are ideal for structural automotive parts due to their mechanical properties. However, the aluminum tends to react with any processing environment at high temperatures and therefore presents significant challenges during manufacturing. One such challenge occurs during secondary cooling, reheating, and hot-rolling and is caused by a reaction with nitrogen-rich atmospheres wherein subsurface aluminum nitride forms in addition to internal and external oxides. The nitrides are detrimental to mechanical properties and cause surface cracks. It is important to understand how these nitrides and oxides form and their consequences for the quality of steel products. This study looks at model iron-aluminum (up to 8 wt.% aluminum) alloys and uses confocal laser scanning microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectrometry, and transmission electron microscopy to study the effect of various conditions on the growth and development of these precipitates in a subsurface oxygen-depleted region. By using model alloys and controlling the experimental atmosphere, this study is able to understand some of the more fundamental materials science behind aluminum nitride formation in aluminum-rich iron alloys and the relationship between internal nitride and oxide precipitation and external oxide scale morphology and composition. The iron-aluminum alloys were heated in N2 atmospheres containing oxygen impurities. It was found that nitrides formed when bulk aluminum content was below 8 wt.% when oxygen was sufficiently depleted due to the internal oxidation. In the samples containing 1 wt.% aluminum, the depth of the internal oxide and nitride zones were in agreement with a diffusion-based model. Increasing aluminum content to 3 and 5 wt% had the effects of modifying the surface-oxide scale composition and increasing its continuity

  3. Reliable aluminum contact formation by electrostatic bonding

    NASA Astrophysics Data System (ADS)

    Kárpáti, T.; Pap, A. E.; Radnóczi, Gy; Beke, B.; Bársony, I.; Fürjes, P.

    2015-07-01

    The paper presents a detailed study of a reliable method developed for aluminum fusion wafer bonding assisted by the electrostatic force evolving during the anodic bonding process. The IC-compatible procedure described allows the parallel formation of electrical and mechanical contacts, facilitating a reliable packaging of electromechanical systems with backside electrical contacts. This fusion bonding method supports the fabrication of complex microelectromechanical systems (MEMS) and micro-opto-electromechanical systems (MOEMS) structures with enhanced temperature stability, which is crucial in mechanical sensor applications such as pressure or force sensors. Due to the applied electrical potential of  -1000 V the Al metal layers are compressed by electrostatic force, and at the bonding temperature of 450 °C intermetallic diffusion causes aluminum ions to migrate between metal layers.

  4. Combustion Characteristics of Hydrocarbon Droplets Induced by Photoignition of Aluminum Nanoparticles (Conference Paper with Briefing Charts)

    DTIC Science & Technology

    2017-04-23

    Hydrocarbon Droplets Induced by Photoignition of Aluminum Nanoparticles (Conference Paper with Briefing Charts) John Bennewitz, Alireza Badakhshan, and...droplets has been achieved through photoignition (PI) utilizing sub milligram of aluminum nanoparticles (Al NPs). For diesel fuel, a reliable ignition...Droplets Induced by Photoignition of Aluminum Nanoparticles Alireza Badakhshan1,*, John W. Bennewitz2, Douglas G. Talley3 1Engineering Research

  5. Nanostructure of aluminum oxide inclusion and formation of hydrogen bubbles in molten aluminum.

    PubMed

    Zeng, Jianmin; Li, Dezhi; Kang, Minglong; He, Huan; Hu, Zhiliu

    2013-10-01

    Hydrogen in molten aluminum is one of the major factors that lead to pore formation in the solidification process of aluminum castings. Previous research showed that aluminum oxide inclusion had a close correlation with the hydrogen content in molten aluminum. Though some researchers thought there must have been a relationship between surface morphology of the inclusion and hydrogen concentration in molten aluminum, very few documents have reported on the surface property of aluminum oxide inclusion. In the present work, AFM (Atomic Force Microscope) was first used to investigate surface morphology of aluminum oxide inclusion in molten aluminum. It was found that there were a large number of nanoscale micropores on the surface of aluminum oxide inclusion. The interior of the micropores was approximated as a tapered shape. These micropores were thought to be helpful to heterogeneous nucleation for hydrogen atoms aggregation because they provided necessary concentration fluctuation and energy undulation for the growth of hydrogen bubbles. Based on the nanostructure observed on the surface of aluminum oxide inclusion, a theoretical model was developed to describe the hydrogen pore formation in aluminum casting under the condition of heterogeneous nucleation.

  6. Coordination between Apoplastic and Symplastic Detoxification Confers Plant Aluminum Resistance1[C][W][OPEN

    PubMed Central

    Zhu, Xiao Fang; Lei, Gui Jie; Wang, Zhi Wei; Shi, Yuan Zhi; Braam, Janet; Li, Gui Xin; Zheng, Shao Jian

    2013-01-01

    Whether aluminum toxicity is an apoplastic or symplastic phenomenon is still a matter of debate. Here, we found that three auxin overproducing mutants, yucca, the recessive mutant superroot2, and superroot1 had increased aluminum sensitivity, while a transfer DNA insertion mutant, xyloglucan endotransglucosylase/hydrolases15 (xth15), showed enhanced aluminum resistance, accompanied by low endogenous indole-3-acetic acid levels, implying that auxin may be involved in plant responses to aluminum stress. We used yucca and xth15 mutants for further study. The two mutants accumulated similar total aluminum in roots and had significantly reduced cell wall aluminum and increased symplastic aluminum content relative to the wild-type ecotype Columbia, indicating that altered aluminum levels in the symplast or cell wall cannot fully explain the differential aluminum resistance of these two mutants. The expression of Al sensitive1 (ALS1), a gene that functions in aluminum redistribution between the cytoplasm and vacuole and contributes to symplastic aluminum detoxification, was less abundant in yucca and more abundant in xth15 than the wild type, consistent with possible ALS1 function conferring altered aluminum sensitivity in the two mutants. Consistent with the idea that xth15 can tolerate more symplastic aluminum because of possible ALS1 targeting to the vacuole, morin staining of yucca root tip sections showed more aluminum accumulation in the cytosol than in the wild type, and xth15 showed reduced morin staining of cytosolic aluminum, even though yucca and xth15 had similar overall symplastic aluminum content. Exogenous application of an active auxin analog, naphthylacetic acid, to the wild type mimicked the aluminum sensitivity and distribution phenotypes of yucca, verifying that auxin may regulate aluminum distribution in cells. Together, these data demonstrate that auxin negatively regulates aluminum tolerance through altering ALS1 expression and aluminum distribution

  7. X-ray photoelectron spectroscopy study of catalyzed aluminum carbide formation at aluminum-carbon interfaces

    NASA Technical Reports Server (NTRS)

    Rabenberg, L.; Maruyama, Benji

    1990-01-01

    Aluminum carbide may form at aluminum-graphite interfaces during the high-temperature processing of graphite fiber-reinforced aluminum metal matrix composites. The chemical interactions leading to the formation of the aluminum carbide in the solid state involve the breaking of the carbon-carbon bonds within the graphite, the transport of the carbon atoms across the interface, and the reaction with the aluminum to form Al4C3. The aluminum carbide formation process has been followed using X-ray photoelectron spectroscopy of model, thin-film, reaction couples. The overall reaction is shown to be catalyzed by the presence of water vapor. Water at the interface increases reaction kinetics by apparently weakening the bonds between the surface carbon atoms and their substrate. This result is in general agreement with what is known to occur during the oxidation of graphite in air.

  8. Formation and properties of stabilized aluminum nanoparticles.

    PubMed

    Meziani, Mohammed J; Bunker, Christopher E; Lu, Fushen; Li, Heting; Wang, Wei; Guliants, Elena A; Quinn, Robert A; Sun, Ya-Ping

    2009-03-01

    The wet-chemical synthesis of aluminum nanoparticles was investigated systematically by using dimethylethylamine alane and 1-methylpyrrolidine alane as precursors and molecules with one or a pair of carboxylic acid groups as surface passivation agents. Dimethylethylamine alane was more reactive, capable of yielding well-defined and dispersed aluminum nanoparticles. 1-Methylpyrrolidine alane was less reactive and more complex in the catalytic decomposition reaction, for which various experimental parameters and conditions were used and evaluated. The results suggested that the passivation agent played dual roles of trapping aluminum particles to keep them nanoscale during the alane decomposition and protecting the aluminum nanoparticles postproduction from surface oxidation and that an appropriate balance between the rate of alane decomposition (depending more sensitively on the reaction temperature) and the timing in the introduction of the passivation agent into the reaction mixture was critical to the desired product mixes and/or morphologies. Some fundamental and technical issues on the alane decomposition and the protection of the resulting aluminum nanoparticles are discussed.

  9. Chromosome-anchored QTL conferring aluminum tolerance in hexaploid oat

    USDA-ARS?s Scientific Manuscript database

    Abstract Aluminum (Al) toxicity is a major constraint on crop production in acid soils around the world. Hexaploid oat (Avena sativa L.) possesses signi'cant Al tolerance making it a good candidate for production in these environments. Genetic improvement for Al tolerance in oat has traditionally be...

  10. Self-assembly formation of lipid bilayer coatings on bare aluminum oxide: overcoming the force of interfacial water.

    PubMed

    Jackman, Joshua A; Tabaei, Seyed R; Zhao, Zhilei; Yorulmaz, Saziye; Cho, Nam-Joon

    2015-01-14

    Widely used in catalysis and biosensing applications, aluminum oxide has become popular for surface functionalization with biological macromolecules, including lipid bilayer coatings. However, it is difficult to form supported lipid bilayers on aluminum oxide, and current methods require covalent surface modification, which masks the interfacial properties of aluminum oxide, and/or complex fabrication techniques with specific conditions. Herein, we addressed this issue by identifying simple and robust strategies to form fluidic lipid bilayers on aluminum oxide. The fabrication of a single lipid bilayer coating was achieved by two methods, vesicle fusion under acidic conditions and solvent-assisted lipid bilayer (SALB) formation under near-physiological pH conditions. Importantly, quartz crystal microbalance with dissipation (QCM-D) monitoring measurements determined that the hydration layer of a supported lipid bilayer on aluminum oxide is appreciably thicker than that of a bilayer on silicon oxide. Fluorescence recovery after photobleaching (FRAP) analysis indicated that the diffusion coefficient of lateral lipid mobility was up to 3-fold greater on silicon oxide than on aluminum oxide. In spite of this hydrodynamic coupling, the diffusion coefficient on aluminum oxide, but not silicon oxide, was sensitive to the ionic strength condition. Extended-DLVO model calculations estimated the thermodynamics of lipid-substrate interactions on aluminum oxide and silicon oxide, and predict that the range of the repulsive hydration force is greater on aluminum oxide, which in turn leads to an increased equilibrium separation distance. Hence, while a strong hydration force likely contributes to the difficulty of bilayer fabrication on aluminum oxide, it also confers advantages by stabilizing lipid bilayers with thicker hydration layers due to confined interfacial water. Such knowledge provides the basis for improved surface functionalization strategies on aluminum oxide

  11. Interlocked by nanoscale sculpturing: pure aluminum copper contacts (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Gerngross-Baytekin, Melike; Gerngross, Mark Daniel; Carstensen, Jürgen; Adelung, Rainer

    2017-06-01

    Connecting metals reliable with different corrosion potential is a well-known challenge. An extreme example are copper aluminum contacts. Galvanic corrosion occurs if the two different metals are in contact with each other and an electrolyte, the aluminum becomes susceptible to corrosion under current flow. Usually, antioxidant pastes containing metals are employed but create difficulties e.g. for fatigue resistant power electronic connections. The recently described process of nanoscale sculpturing [1] offers an alternative. Usually, if the surface of metals like aluminium are prepared they are just arbitrary cuts through the bulk. There is no optimization of the surface grain structure towards stability at all. Neither the crystalline facets in the grains are in their most stable orientation nor is the protective oxide shell the most stable one. The nanoscale sculpturing approach is carving out the most stable grains and planes by chemical or electrochemical treatment. The decisive trick is that the chemistry is targeting towards the instable oxide and not the metal. Aluminium sample surfaces including alloys like AA575 exhibit afterwards single crystalline surface facets covered with nanoscale stable oxide films. Galvanically deposited copper forms extremely reliable interlocked connections on top, even allowing for soldering on top of their surface.

  12. Nanoscale pore formation dynamics during aluminum anodization.

    PubMed

    Thamida, Sunil Kumar; Chang, Hsueh-Chia

    2002-03-01

    A theoretical analysis of nanoscale pore formation during anodization reveals its fundamental instability mechanism to be a field focusing phenomenon when perturbations on the minima of the two oxide interfaces are in phase. Lateral leakage of the layer potential at high wave number introduces a layer tension effect that balances the previous destabilizing effect to produce a long-wave instability and a selected pore separation that scales linearly with respect to voltage. At pH higher than 1.77, pores do not form due to a very thick barrier layer. A weakly nonlinear theory based on long-wave expansion of double free surface problem yields two coupled interface evolution equations that can be reduced to one without altering the dispersion relationship by assuming an equal and in-phase amplitude for the two interfaces. This interface evolution equation faithfully reproduces the initial pore ordering and their dynamics. A hodograph transformation technique is then used to determine the interior dimension of the well-developed pores in two dimensions. The ratio of pore diameter to pore separation is found to be a factor independent of voltage but varies with the pH of the electrolyte. Both the predicted pH range where pores are formed and the predicted pore dimensions are favorably compared to experimental data. (c) 2002 American Institute of Physics.

  13. Formation of nanoscale pores arrays during anodization of aluminum.

    SciTech Connect

    Singh, G. K.; Golovin, A. A.; Aranson, I. S.; Vinokur, V.; Materials Science Division; Northwestern Univ.

    2005-01-01

    A theory of the spontaneous formation of spatially regular hexagonal arrays of nanopores in aluminum oxide film growing during aluminum anodization is presented. Linear stability analysis shows that, in certain ranges of the applied voltage and electrolyte pH, the oxide film is unstable with respect to perturbations with a well-defined wavelength. The instability is caused by a positive feedback between the oxidation-dissolution rates and variations of electric field caused by perturbations of the metal-oxide and oxide-electrolyte interfaces. The competition between this instability and the stabilizing effects of the Laplace pressure and elastic stress provides the wavelength selection mechanism. The hexagonal ordering of pores results from the resonant quadratic nonlinear interaction of unstable modes.

  14. Modeling of microporosity formation in A356 aluminum alloy casting

    NASA Astrophysics Data System (ADS)

    Zhu, J. D.; Cockcroft, S. L.; Maijer, D. M.

    2006-03-01

    A numerical model for predicting microporosity formation in aluminum castings has been developed, which describes the redistribution of hydrogen between solid and liquid phases, the transport of hydrogen in liquid by diffusion, and Darcy flow in the mushy zone. For simulating the nucleation of hydrogen pores, the initial pore radius is assumed to be a function of the secondary dendrite arm spacing, whereas pore growth is based on the assumption that hydrogen activity within the pore and the liquid are in equilibrium. One of the key features of the model is that it uses a two-stage approach for porosity prediction. In the first stage, the volume fraction of porosity is calculated based on the reduced pressure, whereas, in the second stage, at fractions solid greater than the liquid encapsulation point, the fraction porosity is calculated based on the volume of liquid trapped within the continuous solid network, which is estimated using a correlation based on the Niyama parameter. The porosity model is used in conjunction with a thermal model solved using the commercial finite-element package ABAQUS. The parameters influencing the formation of microporosity are discussed including a means to describe the supersaturation of hydrogen necessary for pore nucleation. The model has been applied to examine the evolution of porosity in a series of experimental samples cast using unmodified A356 in which the initial hydrogen content was varied from 0.048 to 0.137 (cc/100 g). A comparison between the model predictions and the experimental measurements indicates good agreement in terms of the variation in porosity with distance from the chill and the variation resulting from initial hydrogen content.

  15. Bifilm Defect Formation in Hydraulic Jump of Liquid Aluminum

    NASA Astrophysics Data System (ADS)

    Hsu, Fu-Yuan

    2016-06-01

    In aluminum gravity casting, as liquid aluminum fell through a vertical sprue and impacted on the horizontal flat surface, a phenomenon known as hydraulic jump ( i.e., flow transition from super-critical to sub-critical flows) was observed. As the jump was transformed, a reverse eddy motion on the surface of the jump was created. This motion entrained aluminum oxide film from the surface into aluminum melt. This folded film (so-called "bifilm" defect) was engulfed by the melt and caused its quality to deteriorate. To understand this phenomenon, aluminum casting experiments and computational modeling were conducted. In the casting experiment, a radius ( R j) to the point where the circular hydraulic jump occurred was measured. This is the circular region of `irregular surface feature', a rough oxidized surface texture near the center area of the castings. To quantify contents of the bifilm defects in the outer region of the jump, the samples in this region were sectioned and re-melted for doing re-melted reduced pressure test (re-melt RPT). An "area-normalized" bifilm index map was plotted to analyze bifilms' population in the samples. The flow transition in the hydraulic jump of liquid aluminum depended on three pressure heads: inertial, gravitational, and surface-tension pressures. A new theoretical equation containing surface tension for describing the flow transition of liquid metal was proposed.

  16. Polyphenol-Aluminum Complex Formation: Implications for Aluminum Tolerance in Plants.

    PubMed

    Zhang, Liangliang; Liu, Ruiqiang; Gung, Benjamin W; Tindall, Steven; Gonzalez, Javier M; Halvorson, Jonathan J; Hagerman, Ann E

    2016-04-20

    Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al(3+) and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and 6. We used spectrophotometric titration and chemometric modeling to determine stability constants and stoichiometries for the aluminum-phenol (AlL) complexes. The structures and spectral features of aluminum-methyl gallate complexes were evaluated with quantum chemical calculations. The high molecular weight polyphenols formed Al3L2 complexes with conditional stability constants (β) ∼ 1 × 10(23) at pH 6 and AlL complexes with β ∼ 1 × 10(5) at pH 4. Methyl gallate formed AlL complexes with β = 1 × 10(6) at pH 6 but did not complex aluminum at pH 4. At intermediate metal-to-polyphenol ratios, high molecular weight polyphenols formed insoluble Al complexes but methyl gallate complexes were soluble. The high molecular weight polyphenols have high affinities and solubility features that are favorable for a role in aluminum detoxification in the environment.

  17. Polyphenol-aluminum complex formation: Implications for aluminum tolerance in plants

    USDA-ARS?s Scientific Manuscript database

    Natural polyphenols may play an important role in aluminum detoxification in some plants. We examined the interaction between Al3+ and the purified high molecular weight polyphenols pentagalloyl glucose (940 Da) and oenothein B (1568 Da), and the related compound methyl gallate (184 Da) at pH 4 and ...

  18. Aluminum-activated citrate and malate transporters from the MATE and ALMT families function independently to confer Arabidopsis aluminum tolerance

    USDA-ARS?s Scientific Manuscript database

    Aluminum (Al) activated root malate and citrate exudation plays an important role in Al tolerance in many plant species. Here, we report on the identification and characterization of AtMATE, a homolog of the recently discovered sorghum and barley Al tolerance genes, here shown to encode an Al-activ...

  19. Aluminum-activated citrate and malate transporters from the MATE and ALMT families function independently to confer Arabidopsis aluminum tolerance

    USDA-ARS?s Scientific Manuscript database

    Aluminum (Al) activated root malate and citrate exudation play an important role in Al tolerance in many plant species. AtALMT1, an Al-activated malate transporter, is a major contributor to Arabidopsis Al tolerance. Here, we demonstrate that a second, unrelated gene, AtMATE, encodes an Arabidopsi...

  20. The effect of surface modification on initial ice formation on aluminum surfaces

    NASA Astrophysics Data System (ADS)

    Rahimi, M.; Afshari, A.; Fojan, P.; Gurevich, L.

    2015-11-01

    One of the most promising energy saving methods in cold climate areas is heat recovery in ventilation system by using air-to-air heat exchangers. However, due to a higher humidity in the exhaust air, there is a risk of ice formation on the heat exchanger fins at subzero temperatures. Since the main material of heat exchanger fins is aluminum, this paper focuses on the effect of aluminum wettability on the initial stages of ice formation. The ice growth was studied on bare as well as hydrophilically and hydrophobically modified surfaces of aluminum (8011A) sheets, commonly used in heat exchangers, at different psychrometric parameters. The obtained results show that the surface modification of aluminum plays a crucial role in the ice formation. We demonstrated that flat hydrophobic surfaces exhibit slower ice growth and denser ice layers, hence making this type of treatment preferable for aluminum heat exchangers. Furthermore we provide an explanation for a commonly observed phenomenon that bare aluminum surfaces are characterized by a faster ice growth and less dense ice layer as compared to both hydrophilically and hydrophobically modified surfaces.

  1. Evidence of involvement of aluminum in causation of defective formation of eggshells and of impaired breeding in wild passerine birds

    SciTech Connect

    Nyholm, N.E.I.

    1981-12-01

    Aluminum was found in the bone marrow tissue of humeri of wild pied flycatchers (Ficedula hypoleuca), specifically in birds with impaired breeding. Production of only small cluthes, defective eggshell formation, and intrauterine bleeding were characteristic impairments shown by the aluminum-contaminated birds. These impairments agree with the symptoms of aluminum intoxication of mammals (including man) reported in the literature. A possible route of transport of aluminum to the birds is presented, in which acid precipitation is the proximate link.

  2. An initial study of void formation during solidification of aluminum in normal and reduced-gravity

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Foerster, George; Gotti, Daniel J.; Neumann, Eric S.; Johnston, J. C.; De Witt, Kenneth J.

    1992-01-01

    Void formation due to volumetric shrinkage during aluminum solidification was observed in real time using a radiographic viewing system in normal and reduced gravity. An end chill directional solidification furnace with water quench was developed to solidify aluminum samples during the approximately 16 seconds of reduced gravity (+/- 0.02g) achieved by flying an aircraft through a parabolic trajectory. Void formation was recorded for two cases: first a nonwetting system; and second, a wetting system where wetting occurs between the aluminum and crucible lid. The void formation in the nonwetting case is similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case in reduced gravity, surface tension causes two voids to form in the top corners of the crucible, but in normal gravity only one large voids forms across the top.

  3. An initial study of void formation during solidification of aluminum in normal and reduced-gravity

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Foerster, George; Gotti, Daniel J.; Neumann, Eric S.; Johnston, J. C.; De Witt, Kenneth J.

    1992-01-01

    Void formation due to volumetric shrinkage during aluminum solidification was observed in real time using a radiographic viewing system in normal and reduced gravity. An end chill directional solidification furnace with water quench was developed to solidify aluminum samples during the approximately 16 seconds of reduced gravity (+/- 0.02g) achieved by flying an aircraft through a parabolic trajectory. Void formation was recorded for two cases: first a nonwetting system; and second, a wetting system where wetting occurs between the aluminum and crucible lid. The void formation in the nonwetting case is similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case in reduced gravity, surface tension causes two voids to form in the top corners of the crucible, but in normal gravity only one large voids forms across the top.

  4. On the Formation of Lightweight Nanocrystalline Aluminum Alloys by Electrodeposition

    NASA Astrophysics Data System (ADS)

    Hilty, Robert D.; Masur, Lawrence J.

    2017-08-01

    New nanocrystalline aluminum alloys have been fabricated by electrodeposition. These are thermodynamically stable alloys of Al-Mn and Al-Zr with grain sizes <100 nm. Al-Mn and Al-Zr alloys are characterized here showing high strength (up to 1350 MPa) and hardness (up to 450 HVN) while maintaining the specific gravity of Al. Smooth and dense deposits plated from ionic liquids, such as EMIM:Cl (1-Ethyl-3-methylimidazolium chloride), can develop to thicknesses of 1 mm or more.

  5. Tissue and cellular basis for impaired bone formation in aluminum-related osteomalacia in the pig.

    PubMed Central

    Sedman, A B; Alfrey, A C; Miller, N L; Goodman, W G

    1987-01-01

    Bone formation is impaired in aluminum-associated bone disease. Reductions in the number of osteoblasts or in the function of individual osteoblasts could account for this finding. Thus, quantitative bone histology and measurements of bone formation were done at three skeletal sites in piglets given aluminum (Al) parenterally, 1.5 mg/kg per d, for 8 wk (Al, n = 4) and in control animals (C, n = 4). Bone Al was 241 +/- 40 mg/kg per dry weight in Al and 1.6 +/- 0.9 in C, P less than 0.001. All Al-treated animals developed osteomalacia with increases in osteoid seam width, osteoid volume, and mineralization lag time at each skeletal site, P less than 0.05 vs. C for all values. Mineralized bone formation at the tissue level was lower in Al than in C, P less than 0.05 for each skeletal site, due to reductions in active bone forming surface. Bone formation at the cellular level was similar in each group, however, and total osteoid production by osteoblasts did not differ in C and Al. Aluminum impairs the formation of mineralized bone in vivo by decreasing the number of active osteoblasts, and this change can be distinguished from the effect of aluminum to inhibit, either directly or indirectly, the calcification of osteoid. PMID:3793934

  6. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates.

    PubMed

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-12-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film РАА/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.The study showed that the structure of the Al films is defined by the deposition rate of aluminum and the thickness of the film. We saw that under anodization in 0.3 M aqueous oxalic acid solution at a voltage of 40 V, the PAA film with a disordered array of pores was formed on aluminum films 200-600 nm thick, which were deposited on glass substrates with an ultra-thin adhesive Nb layer. The research revealed the formation of two differently sized types of pores. The first type of pores is formed on the grain boundaries of aluminum film, and the pores are directed perpendicularly to the surface of aluminum. The second type of pores is formed directly on the grains of aluminum. They are directed perpendicularly to the grain plains. There is a clear tendency to self-ordering in this type of pores.

  7. The entropy and Gibbs free energy of formation of the aluminum ion

    USGS Publications Warehouse

    Hemingway, B.S.; Robie, R.A.

    1977-01-01

    A reevaluation of the entropy and Gibbs free energy of formation of Al3+(aq) yields -308 ?? 15 J/K??mol and 489.4 ?? 1.4kj/mol for S0298 and ??G0f{hook},298 respectively. The standard electrode potential for aluminum is 1.691 ?? 0.005 volts. ?? 1977.

  8. A gene in the multidrug and toxic compound extrusion (MATE) family confers aluminum tolerance in sorghum.

    PubMed

    Magalhaes, Jurandir V; Liu, Jiping; Guimarães, Claudia T; Lana, Ubiraci G P; Alves, Vera M C; Wang, Yi-Hong; Schaffert, Robert E; Hoekenga, Owen A; Piñeros, Miguel A; Shaff, Jon E; Klein, Patricia E; Carneiro, Newton P; Coelho, Cintia M; Trick, Harold N; Kochian, Leon V

    2007-09-01

    Crop yields are significantly reduced by aluminum toxicity on highly acidic soils, which comprise up to 50% of the world's arable land. Candidate aluminum tolerance proteins include organic acid efflux transporters, with the organic acids forming non-toxic complexes with rhizosphere aluminum. In this study, we used positional cloning to identify the gene encoding a member of the multidrug and toxic compound extrusion (MATE) family, an aluminum-activated citrate transporter, as responsible for the major sorghum (Sorghum bicolor) aluminum tolerance locus, Alt(SB). Polymorphisms in regulatory regions of Alt(SB) are likely to contribute to large allelic effects, acting to increase Alt(SB) expression in the root apex of tolerant genotypes. Furthermore, aluminum-inducible Alt(SB) expression is associated with induction of aluminum tolerance via enhanced root citrate exudation. These findings will allow us to identify superior Alt(SB) haplotypes that can be incorporated via molecular breeding and biotechnology into acid soil breeding programs, thus helping to increase crop yields in developing countries where acidic soils predominate.

  9. High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

    PubMed Central

    Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.

    2013-01-01

    Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573

  10. Formation and decomposition of AlH3 in the aluminum-hydrogen system

    NASA Astrophysics Data System (ADS)

    Saitoh, H.; Machida, A.; Katayama, Y.; Aoki, K.

    2008-10-01

    The pressure-temperature diagram of hydrogen-aluminum system was determined for a pressure range of 0-10GPa and a temperature range of 27-800°C by in situ x-ray diffraction measurements. Pristine aluminum was hydrogenated to trihydride at 8.9GPa and 600°C. The cyclic formation and decomposition of the hydride resulted in lowering of the hydrogenation conditions down to 4.9GPa and 330°C. Transparent single crystals were recovered at ambient conditions.

  11. Cold gas dynamic spraying of aluminum: The role of substrate characteristics in deposit formation

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Shipway, P. H.; McCartney, D. G.

    2005-03-01

    Aluminum powder of 99.7 wt.% purity and in the nominal particle size range of -75+15 µm has been sprayed onto a range of substrates by cold gas dynamic spraying (cold spraying) with helium, at room temperature, as the accelerating gas. The substrates examined include metals with a range of hardness, polymers, and ceramics. The substrate surfaces had low roughness (R a < 0.1 µm) before deposition of aluminum in an attempt to separate effects of mechanical bonding from other forms of bonding, such as chemical or metallurgical bonding. The cross-sectional area of a single track of aluminum sprayed onto the substrate was taken as a measure of the ease of initiation of deposition, assuming that once a coating had begun to deposit onto a substrate, its growth would occur at a constant rate regardless of substrate type. It has been shown that initiation of deposition depends critically upon substrate type. For metals where initiation was not easy, small aluminum particles were deposited preferentially to large ones (due to their higher impact velocities); these may have acted as an interlayer to promote further building of the coating. A number of phenomena have been observed following spraying onto various substrates, such as substrate melting, substrate and particle deformation, and evidence for the formation of a metal-jet (akin to that seen in explosive welding). Such phenomena have been related to the processes occurring during impact of the particles on the substrate. Generally, initiation of aluminum deposition was poor for nonmetallic materials (where no metallic bonding between the particle and substrate was possible) and for very soft metals (in the case of tin, melting of the substrate was observed). Metallic substrates harder than the aluminum particles generally promoted deposition, although deposition onto aluminum alloy was difficult due to the presence of a tenacious oxide layer. Initiation was seen to be rapid on hard metallic substrates, even when

  12. The influence of mechanochemical activation on coke formation on aluminum oxide

    SciTech Connect

    Chesnokov, V.V.; Molchanov, V.V.; Paukshtis, E.A.

    1995-09-01

    Processes occurring during mechanochemical activation (MA) of {gamma}-Al{sub 2}O{sub 3} are studied by physicochemical methods. As a result of MA, the surface concentration of coordinatively unsaturated aluminum ions falls. The concentration of strong Lewis acid sites decreases by two orders of magnitude, and that of weak Lewis centers falls several times, whereas the bulk concentration of octahedrally and tetrahedrally coordinated aluminum ions remains unchanged. MA of {gamma}-Al{sub 2}O{sub 3} is shown to suppress coke formation. The reason behind this effect is the decrease in the concentration of acceptor sites involved in the active sites responsible for coke formation at the surface of alumina. The strongest acceptor sites vanish at the initial stages of MA. The contribution of these centers in the coke formation on alumina is insignificant, whereas the weaker acceptor sites that are more resistant to MA make an essential contribution.

  13. Induction of de novo bone formation in the beagle. A novel effect of aluminum.

    PubMed Central

    Quarles, L D; Gitelman, H J; Drezner, M K

    1988-01-01

    To define the primary effects of aluminum on bone in the mammalian species, we examined the dose/time-dependent actions of aluminum in normal beagles. Administration of low dose aluminum (0.75 mg/kg) significantly elevated the serum aluminum (151.7 +/- 19.9 micrograms/liter) compared with that in controls (4.2 +/- 1.35 micrograms/liter) but did not alter the calcium, creatinine, or parathyroid hormone. After 8 wk of therapy, bone biopsies displayed reduced bone resorption (2.6 +/- 0.63 vs. 4.5 +/- 0.39%) and osteoblast covered bone surfaces (2.02 +/- 0.51 vs. 7.64 +/- 1.86%), which was indicative of low turnover. In contrast, prolonged treatment resulted in increased bone volume and trabecular number (38.9 +/- 1.35 vs. 25.2 +/- 2.56% and 3.56 +/- 0.23 vs. 2.88 +/- 0.11/mm) which was consistent with uncoupled bone formation. Administration of higher doses of aluminum (1.20 mg/kg) increased the serum aluminum further (1242.3 +/- 259.8 micrograms/liter) but did not affect calcium, creatinine, or parathyroid hormone. However, after 8 wk of treatment, bone biopsies displayed changes similar to those after long-term, low-dose therapy. In this regard, an increased trabecular number (3.41 +/- 0.18/mm) and bone volume (36.5 +/- 2.38%) again provided evidence of uncoupled bone formation. In contrast, in this instance poorly mineralized woven bone contributed to the enhanced bone volume. High-dose treatment for 16 wk further enhanced bone volume (50.4 +/- 4.61%) and trabecular number (3.90 +/- 0.5/mm). These observations illustrate that aluminum may stimulate uncoupled bone formation and induce a positive bone balance. This enhancement of bone histogenesis contrasts with the effects of pharmacologic agents that alter the function of existing bone remodeling units. Images PMID:3350964

  14. Investigation on Formation Mechanism of Irregular Shape Porosity in Hypoeutectic Aluminum Alloy by X-Ray Real Time Observation

    NASA Astrophysics Data System (ADS)

    Liao, Hengcheng; Zhao, Lei; Wu, Yuna; Fan, Ran; Wang, Qigui; Pan, Ye

    2012-08-01

    The formation mechanism of irregular shape porosity in hypoeutectic aluminum silicon alloy (A356) was investigated by X-ray real time observation on porosity evolution during solidification and re-melting. Porosity in the hypoeutectic aluminum A356 alloy with high hydrogen content (>0.3 mL/100 g Al) first forms in the liquid as small spherical gas bubbles, then expands along with the pressure drop in the mushy zone due to shrinkage and lack of feeding, and finally deforms into irregular morphology by the impingement of aluminum dendrite network. Degassing is a key to eliminate porosity in aluminum alloy castings.

  15. The texture and formation of shear bands in a hot rolled 7050 aluminum alloy

    SciTech Connect

    Chang, S.C.; Jiang, Q.D.; Hu, J.R.; Chen, F.R.

    1998-08-04

    The mechanical properties of the high-strength 7XXX series aluminum alloys can be improved through microstructural modifications in addition to alloy compositional changes. Among microstructural features, the effect of texture on mechanical properties was least well understood. By plastic deformation of a metal specimen, the crystalline lattice rotates toward one or more stable (preferred) orientations, thus establishing a deformation texture. Since the rolling process tends to increase the tendency of a sharp texture and the localization of plastic deformation, it is interesting to study in detail the influence of texture on the deformation behavior of a rolled metal. The studies in the past investigated mainly the influences of microstructural features on the material properties under tensile stress. Since compression is more closely related to most metal working processes, the objective of this study is to investigate the formation of shear band in compression and the effect on texture on the shear band formation of a 7050-T7451 aluminum alloy.

  16. Dealloying of Platinum-Aluminum Thin Films: Dynamics of Pattern Formation

    NASA Astrophysics Data System (ADS)

    Galinski, Henning; Ryll, Thomas; Schlagenhauf, Lukas; Rechberger, Felix; Ying, Sun; Gauckler, Ludwig J.; Mornaghini, Flavio C. F.; Ries, Yasmina; Spolenak, Ralph; Döbeli, Max

    2011-11-01

    The application of focused ion beam (FIB) nanotomography and Rutherford backscattering spectroscopy (RBS) to dealloyed platinum-aluminum thin films allows for an in-depth analysis of the dominating physical mechanisms of nanoporosity formation during the dealloying process. The porosity formation due to the dissolution of the less noble aluminum in the alloy is treated as result of a reaction-diffusion system. The RBS and FIB analysis yields that the porosity evolution has to be regarded as superposition of two independent processes, a linearly propagating diffusion front with a uniform speed and a slower dissolution process in regions which have already been passed by the diffusion front. The experimentally observed front evolution is captured by the Fisher-Kolmogorov-Petrovskii-Piskounov (FKPP). The slower dissolution is represented by a zero-order rate law which causes a gradual porosity in the thin film.

  17. Suppression of phospholipase D,gammas confers increased aluminum resistance in Arabidopsis thaliana

    USDA-ARS?s Scientific Manuscript database

    Aluminum (Al) toxicity is the major stress in acidic soil that comprises about 50% of the world’s arable land. The complex molecular mechanisms of Al toxicity have yet to be fully determined. As a barrier to Al entrance and attack, plant cell membranes play essential roles in Al toxicity, as lipid c...

  18. The formation mechanism of aluminum oxide tunnel barriers.

    SciTech Connect

    Cerezo, A.; Petford-Long, A. K.; Larson, D. J.; Pinitsoontorn, S.; Singleton, E. W.; Materials Science Division; Univ. Oxford; Seagate Tech.

    2006-01-01

    The functional properties of magnetic tunnel junctions are critically dependant on the nanoscale morphology of the insulating barrier (usually only a few atomic layers thick) that separates the two ferromagnetic layers. Three-dimensional atom probe analysis has been used to study the chemistry of a magnetic tunnel junction structure comprising an aluminium oxide barrier formed by in situ oxidation, both in the under-oxidized and fully oxidized states and before and after annealing. Low oxidation times result in discrete oxide islands. Further oxidation leads to a more continuous, but still non-stoichiometric, barrier with evidence that oxidation proceeds along the top of grain boundaries in the underlying CoFe layer. Post-deposition annealing leads to an increase in the barrier area, but only in the case of the fully oxidized and annealed structure is a continuous planar layer formed, which is close to the stoichiometric Al:O ratio of 2:3. These results are surprising, in that the planar layers are usually considered unstable with respect to breaking up into separate islands. Analysis of the various driving forces suggests that the formation of a continuous layer requires a combination of factors, including the strain energy resulting from the expansion of the oxide during internal oxidation on annealing.

  19. Modeling of microporosity formation during solidification of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Wang, T.; An, D.; Zhang, Q.; Dai, T.; Zhu, M.

    2015-06-01

    A two-dimensional (2D) multi-phase cellular automaton (MCA) model is adopted to simulate the dendrite and microporosity formation during solidification of aluminium alloys. The model involves three phases of liquid, gas, and solid. The effect of liquid-solid phase transformation on the nucleation and growth of porosity, the redistribution and diffusion of solute and hydrogen, and the effects of surface tension and environmental pressure are taken into account. The growth of both dendrite and porosity is simulated using a CA approach. The diffusion of solute and hydrogen is calculated using the finite difference (FD) method. The simulations can reveal the interactive and competitive growth of dendrites and micropores, and the microsegregationof solute and hydrogen. The porosity nuclei with large size are able to grow preferentially, while the growth of the small porosity nuclei is inhibited. Gas pores grow spherically when it is enveloped by liquid. After touching with dendrites, the shapes of pores become irregular. An increased initial hydrogen concentration reduces the incubation time of porosity nucleation, but increases the final percentage of porosity and the average porosity size at the eutectic temperature. With cooling rate decreasing, the competitive growth between gas pores becomes more evident, leading to non-uniform porosity sizes, and more irregular morphology of the porosities with larger size. The simulation results are compared reasonably well with the experimental data reported in literature.

  20. Removal of Vanadium from Molten Aluminum-Part I. Analysis of VB2 Formation

    NASA Astrophysics Data System (ADS)

    Khaliq, Abdul; Rhamdhani, Muhammad Akbar; Brooks, Geoffrey A.; Grandfield, John F.

    2014-04-01

    Aluminum has been used as an alternative to copper for electrical conductor applications. However, the presence of certain impurities in aluminum, such as V, Ti, Zr, Cr, and Fe, has detrimental effect on its electrical conductivity. These impurities can be removed by the addition of an Al-B master alloy containing AlB2 or AlB12 phase, known as boron treatment. The detailed mechanism of borides formation, however, is not well understood. In the current study, a systematic investigation of vanadium diborides (VB2) formation in the Al-V-B alloys was carried out. The study comprised thermodynamic assessment and experimental investigation on the Al-V-B system under typical industrial processing conditions. It was predicted from thermodynamic analysis that VB2 are stable borides of V and do not dissolve readily in the temperatures ranging from 948 K to 1173 K (675 °C to 900 °C). The experimental investigation showed that the mechanism of VB2 formation and V removal in an Al-V-B system is complex as it involves a number of steps such as chemical reaction, mass transfers in bulk liquid and inside the VB2 ring, and diffusions of B and V through the VB2 layer. Comparative analysis of thermodynamic and experimental results showed that the aluminum alloys were far from equilibrium and that the overall process was limited by the kinetics of B diffusion through the VB2 ring.

  1. Formation of Deposits on the Cathode Surface of Aluminum Electrolysis Cells

    NASA Astrophysics Data System (ADS)

    Allard, François; Soucy, Gervais; Rivoaland, Loig

    2014-12-01

    The efficiency of electrolysis cells for aluminum production is reduced when deposits are formed on the cathode block surface. Overfeeding of alumina or excessive heat loss in industrial cells leads to the formation of highly resistive deposits. In this study, the chemical composition of sludge, ledge toe, and thin deposits was investigated at the bottom of both industrial and experimental electrolysis cells. The formation of deposits in laboratory experiments was demonstrated in acidic, neutral, and basic electrolytic bath. A gradient of chiolite (Na5Al3F14) and α-Al2O3 was observed in the deposits. The bath at the bottom of the experimental electrolysis cell had a higher cryolite ratio implying a higher liquidus temperature. The sludge formed at the bottom of the cell can lift the aluminum metal resulting in an important reduction of the contact surface between the aluminum and the cathode block. Moreover, the deposits disturb the current path and generate horizontal current components in the metal which enhance the motion and lower the current efficiency. A thin film of bath supersaturated in alumina was observed under the metal. This work provides clarification on the formation mechanisms of the various deposits responsible for the deterioration of the cathode surface.

  2. Formation and evolution of tweed structures on high-purity aluminum polycrystalline foils under cyclic tension

    SciTech Connect

    Kuznetsov, P. V.; Vlasov, I. V.; Sklyarova, E. A.; Smekalina, T. V.

    2015-10-27

    Peculiarities of formation and evolution of tweed structures on the surface of high-purity aluminum polycrystalline foils under cyclic tension were studied using an atom force microscope and a white light interferometer. Tweed structures of micron and submicron sizes were found on the foils at different number of cycles. In the range of 42,000 < N < 95,000 cycles destruction of tweed patterns is observed, which leads to their disappearance from the surface of the foils. Formation of tweed structures of various scales is discussed in terms of the Grinfeld instability.

  3. Formation and emission of brominated dioxins and furans during secondary aluminum smelting processes.

    PubMed

    Wang, Mei; Liu, Guorui; Jiang, Xiaoxu; Li, Sumei; Liu, Wenbin; Zheng, Minghui

    2016-03-01

    Secondary aluminum smelting (SAl) processes have previously been found to be important sources of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs). It is crucial that the key factors that influence the formation and emission of PBDD/Fs are identified to allow techniques for decreasing PBDD/F emissions during SAl processes to be developed. In this study, stack gas samples were collected from four typical secondary aluminum smelters that used different raw materials, and the samples were analyzed to allow differences between PBDD/F emissions from different SAl plants to be assessed. The composition of the raw materials was found to be one of the key factors influencing the amounts of PBDD/Fs emitted. The PBDD/F emission factors (per tonne of aluminum produced) for the plants using 100% (Plant1), 80% (Plant2), and 50% (Plant3) dirty aluminum scrap in the raw material feed were 180, 86, and 14 μg t(-1), respectively. The amounts of PBDD/Fs emitted at different stages of the smelting process (feeding-fusion, refining, and casting) were compared, and the feeding-fusion stage was found to be the main stage in which PBDD/Fs were formed and emitted. Effective aluminum scrap pretreatments could significantly decrease PBDD/F emissions. Much higher polybrominated dibenzofuran concentrations than polybrominated dibenzo-p-dioxin concentrations were found throughout the SAl process. The more-brominated congeners (including octabromodibenzo-p-dioxin, octabromodibenzofuran, heptabromodibenzo-p-dioxins, and heptabromodibenzofurans) were the dominant contributors to the total PBDD/F concentrations. The results could help in the development of techniques and strategies for controlling PBDD/F emissions during metallurgical processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Dross formation mechanism and development of wear resistant scraper in aluminum-silicon-zinc coating bath

    NASA Astrophysics Data System (ADS)

    Varadarajan, Ashok

    Steel sheet manufacturers across the globe, face a huge loss of production due to the molten metal corrosion of the pot hardware in continuous galvanizing lines. The development of steel sheet with corrosion resistant for more than 30 years using a high aluminum content zinc coating has made an impact in the construction industry. High aluminum content bath (55 wt%) causes severe corrosion of the pot hardware and causes huge repair and replacement cost with frequent stoppages. One of the main reasons for stoppages is the severe dross formation over the submerged hardware (sink roll), which results in poor coating layer over the steel sheet. Complete understanding of the mechanism of the dross formation over the submerged hardware has not yet been completely achieved. In order to establish the dross formation mechanism, an array of tests was performed. Initial inhibition of Al attack by the silicon rich layer and further formation of Fe2Al 5 layer hindering the diffusion of the Al into the substrate were observed. Also, the effect of the hydrodynamic motion of the bathe in the dross formation mechanism was established. A series of tests for efficient removal of the dross formed over the sink roll using high hardness, corrosion resistant materials were conducted at 600°C. After these tests, an efficient scraping process with a potential for energy and cost savings was developed with a better scraper material, resulting in a reduction of 75% in line stoppages.

  5. Physical Simulation Method for the Investigation of Weld Seam Formation During the Extrusion of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Nguyen, Duc-Thien; Zhou, Jie

    2016-12-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of great importance to understand the formation of weld seams inside the welding chamber during extrusion, as affected by extrusion process variables and die design. Previously developed physical simulation methods could not fully reproduce the thermomechanical conditions inside the welding chamber of porthole die. In this research, a novel physical simulation method for the investigation of weld seam formation during extrusion was developed. With a tailor-designed tooling set mounted on a universal testing machine, the effects of temperature, speed, and strain on the weld seam quality of the 6063 alloy were investigated. The strains inside the welding chamber were found to be of paramount importance for the bonding of metal streams, accompanied by microstructural changes, i.e., recovery or recrystallization, depending on the local deformation condition. The method was shown to be able to provide guidelines for the design of porthole dies and choice of extrusion process variables, thereby reducing the scrap rate of aluminum extrusion operation.

  6. Physical Simulation Method for the Investigation of Weld Seam Formation During the Extrusion of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Nguyen, Duc-Thien; Zhou, Jie

    2017-04-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of great importance to understand the formation of weld seams inside the welding chamber during extrusion, as affected by extrusion process variables and die design. Previously developed physical simulation methods could not fully reproduce the thermomechanical conditions inside the welding chamber of porthole die. In this research, a novel physical simulation method for the investigation of weld seam formation during extrusion was developed. With a tailor-designed tooling set mounted on a universal testing machine, the effects of temperature, speed, and strain on the weld seam quality of the 6063 alloy were investigated. The strains inside the welding chamber were found to be of paramount importance for the bonding of metal streams, accompanied by microstructural changes, i.e., recovery or recrystallization, depending on the local deformation condition. The method was shown to be able to provide guidelines for the design of porthole dies and choice of extrusion process variables, thereby reducing the scrap rate of aluminum extrusion operation.

  7. Laser beam welding of aluminum die casting with reduced pore formation

    SciTech Connect

    Rehbein, D.H.; Decker, I.; Wohlfahrt, H.

    1994-12-31

    Laser beam welding is already well treated within the laboratory, but there is still a minor industrial application because of the lack of reliability of the process due to violent fluctuations of the plasma formation above and melt flow turbulence around the welding key-hole. An even greater challenge is the welding of die cast aluminum since the high hydrogen content dissolved within the material during the casting process is responsible for a strong pore formation of the weld and a rather unsteady welding process. During the last 10 years, intensive research work has been executed by the research institute of the authors in order to increase the weldability of die-case aluminum by optimization of the casting process. The casting process has been optimized in such a way that as few gases as possible can penetrate into the castings. The porosity of the welds has been reduced to a level comparable to that of high-quality joints of wrought material. The weld quality achieved by electron beam welding is excellent. The range of possible welding speeds and the necessary laser power depending on the wall thickness and the chosen optical arrangement are quantified. Die casting of aluminum is a manufacturing operation of high productivity. However, it s not suited for production of hollow structures. A combination with a highly productive welding technique such as laser beam welding is now available, and one may expect it to be of reasonable economic benefit in the future.

  8. In vivo stimulation of bone formation by aluminum and oxygen plasma surface-modified magnesium implants.

    PubMed

    Wong, Hoi Man; Zhao, Ying; Tam, Vivian; Wu, Shuilin; Chu, Paul K; Zheng, Yufeng; To, Michael Kai Tsun; Leung, Frankie K L; Luk, Keith D K; Cheung, Kenneth M C; Yeung, Kelvin W K

    2013-12-01

    A newly developed magnesium implant is used to stimulate bone formation in vivo. The magnesium implant after undergoing dual aluminum and oxygen plasma implantation is able to suppress rapid corrosion, leaching of magnesium ions, as well as hydrogen gas release from the biodegradable alloy in simulated body fluid (SBF). No released aluminum is detected from the SBF extract and enhanced corrosion resistance properties are confirmed by electrochemical tests. In vitro studies reveal enhanced growth of GFP mouse osteoblasts on the aluminum oxide coated sample, but not on the untreated sample. In addition to that a small amount (50 ppm) of magnesium ions can enhance osteogenic differentiation as reported previously, our present data show a low concentration of hydrogen can give rise to the same effect. To compare the bone volume change between the plasma-treated magnesium implant and untreated control, micro-computed tomography is performed and the plasma-treated implant is found to induce significant new bone formation adjacent to the implant from day 1 until the end of the animal study. On the contrary, bone loss is observed during the first week post-operation from the untreated magnesium sample. Owing to the protection offered by the Al2O3 layer, the plasma-treated implant degrades more slowly and the small amount of released magnesium ions stimulate new bone formation locally as revealed by histological analyses. Scanning electron microscopy discloses that the Al2O3 layer at the bone-implant interface is still present two months after implantation. In addition, no inflammation or tissue necrosis is observed from both treated and untreated implants. These promising results suggest that the plasma-treated magnesium implant can stimulate bone formation in vivo in a minimal invasive way and without causing post-operative complications.

  9. Overexpression of Citrus junos mitochondrial citrate synthase gene in Nicotiana benthamiana confers aluminum tolerance.

    PubMed

    Deng, Wei; Luo, Keming; Li, Zhengguo; Yang, Yingwu; Hu, Nan; Wu, Yu

    2009-07-01

    Aluminum (Al) toxicity is one of the major factors that limit plant growth in acid soils. Al-induced release of organic acids into rhizosphere from the root apex has been identified as a major Al-tolerance mechanism in many plant species. In this study, Al tolerance of Yuzu (Citrus Junos Sieb. ex Tanaka) was tested on the basis of root elongation and the results demonstrated that Yuzu was Al tolerant compared with other plant species. Exposure to Al triggered the exudation of citrate from the Yuzu root. Thus, the mechanism of Al tolerance in Yuzu involved an Al-inducible increase in citrate release. Aluminum also elicited an increase of citrate content and increased the expression level of mitochondrial citrate synthase (CjCS) gene and enzyme activity in Yuzu. The CjCS gene was cloned from Yuzu and overexpressed in Nicotiana benthamiana using Agrobacterium tumefaciens-mediated methods. Increased expression level of the CjCS gene and enhanced enzyme activity were observed in transgenic plants compared with the wild-type plants. Root growth experiments showed that transgenic plants have enhanced levels of Al tolerance. The transgenic Nicotiana plants showed increased levels of citrate in roots compared to wild-type plants. The exudation of citrate from roots of the transgenic plants significantly increased when exposed to Al. The results with transgenic plants suggest that overexpression of mitochondrial CS can be a useful tool to achieve Al tolerance.

  10. Zinc-nanosystem-structure formation using anodic-oxidized aluminum membranes

    NASA Astrophysics Data System (ADS)

    Kornyushchenko, A. S.; Perekrestov, V. I.; Natalich, V. V.; Zagaiko, I. V.

    2017-02-01

    We propose a new method for the formation of zinc nanosystems by condensation of a weakly supersaturated Zn vapor in pores of the anodic-oxidized aluminum membrane (AOA)-silicon substrate system. For this purpose, a weak Zn vapor flow is created by magnetron sputtering of Zn target in a high-purity inert gas atmosphere and maintaining a temperature of the porous AOA membrane outer surface higher than that of the substrate. This drives a directional Zn vapor flow inward membrane parallel to the pore generatrix and favors effective penetration of Zn vapor into the membrane.

  11. Formation of calcium in the products of iron oxide-aluminum thermite combustion in air

    NASA Astrophysics Data System (ADS)

    Gromov, A. A.; Gromov, A. M.; Popenko, E. M.; Sergienko, A. V.; Sabinskaya, O. G.; Raab, B.; Teipel, U.

    2016-10-01

    The composition of condensed products resulting from the combustion of thermite mixtures (Al + Fe2O3) in air is studied by precise methods. It is shown that during combustion, calcium is formed and stabilized in amounts of maximal 0.55 wt %, while is missing from reactants of 99.7 wt % purity. To explain this, it is hypothesized that a low-energy nuclear reaction takes place alongside the reactions of aluminum oxidation and nitridation, resulting in the formation of calcium (Kervran-Bolotov reaction).

  12. Aluminum-Mediated Formation of Cyclic Carbonates: Benchmarking Catalytic Performance Metrics.

    PubMed

    Rintjema, Jeroen; Kleij, Arjan W

    2017-03-22

    We report a comparative study on the activity of a series of fifteen binary catalysts derived from various reported aluminum-based complexes. A benchmarking of their initial rates in the coupling of various terminal and internal epoxides in the presence of three different nucleophilic additives was carried out, providing for the first time a useful comparison of activity metrics in the area of cyclic organic carbonate formation. These investigations provide a useful framework for how to realistically valorize relative reactivities and which features are important when considering the ideal operational window of each binary catalyst system. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Structure formation and properties of a copper-aluminum joint produced by ultrasound-assisted explosive welding

    NASA Astrophysics Data System (ADS)

    Kuz'min, E. V.; Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.

    2017-08-01

    The effect of ultrasound-assisted explosive welding on the structure formation and the properties of copper-aluminum joints is studied. Ultrasound-assisted explosive welding improves the quality of formed copper-aluminum joints, i.e., enhances their strength and significantly reduces the amount of fused metal over the entire weldability range. It is shown that ultrasound-assisted explosive welding can noticeably extend the weldability range of the copper-aluminum pair to obtain equal-in-strength joints with minimum structural heterogeneity in the wide welding range.

  14. Short-term aluminum administration in the rat. Effects on bone formation and relationship to renal osteomalacia.

    PubMed Central

    Goodman, W G; Gilligan, J; Horst, R

    1984-01-01

    Aluminum may be pathogenic in the osteomalacia observed in some patients receiving hemodialysis. To study the early effects of Al on bone growth, bone formation, mineralization, and resorption were measured during short-term Al exposure in the tibial cortex of pair-fed control (C, n = 10), aluminum-treated (AL, n = 9), subtotally nephrectomized control (NX-C, n = 7), and subtotally nephrectomized aluminum-treated (NX-AL, n = 8) rats using double tetracycline labeling of bone. Animals received 2 mg/d of elemental Al intraperitoneally for 5 d/wk over 4 wk. Total bone and matrix (osteoid) formation, periosteal bone and matrix formation, and periosteal bone and matrix apposition fell by 20% in AL from C, P less than 0.05 for all values, and by 40% in NX-AL from NX-C, P less than 0.01 for all values. Moreover, each measurement was significantly less in NX-AL than in AL, P less than 0.05 for all values. Osteoid width did not increase following aluminum administration in either AL or NX-AL. Resorption surface increased from control values in both AL and NX-AL; also, resorptive activity at the endosteum was greater in NX-AL than in NX-C, P less than 0.05. Thus, aluminum impairs new bone and matrix formation but does not cause classic osteomalacia in the cortical bone of rats whether renal function is normal or reduced. These findings may represent either a different response to aluminum administration in cortical bone as contrasted to trabecular bone or an early phase in the development of osteomalacia. Aluminum may increase bone resorption and contribute to osteopenia in clinical states associated with aluminum accumulation in bone. PMID:6690476

  15. A Computer Conference Format for Teaching Medical Ethics.

    ERIC Educational Resources Information Center

    Barclay, Mel L.; Elkins, Thomas E.

    1991-01-01

    The University of Michigan uses computer teleconferencing to extend classroom interaction beyond classroom hours and space. Using this computer conference to present, explore, and discuss medical ethics issues makes students active, thoughtful participants and makes discussion easier. Current case materials are presented before classroom…

  16. A Computer Conference Format for Teaching Medical Ethics.

    ERIC Educational Resources Information Center

    Barclay, Mel L.; Elkins, Thomas E.

    1991-01-01

    The University of Michigan uses computer teleconferencing to extend classroom interaction beyond classroom hours and space. Using this computer conference to present, explore, and discuss medical ethics issues makes students active, thoughtful participants and makes discussion easier. Current case materials are presented before classroom…

  17. Mechanism of Ultrafine Grain Formation During Intense Plastic Straining in an Aluminum Alloy at Intermediate Temperatures

    SciTech Connect

    Kaibyshev, R.; Sitdikov, O.; Mazurina, I,; Lesuer, D. R.

    2000-09-21

    The mechanism of grain formation during equal channel angular extrusion (ECAE) in a 2219 Al alloy has been studied at intermediate and high temperatures. It was shown that continuous dynamic recrystallization (CDRX) occurred during intense plastic straining and resulted in the formation of submicrometer grains at temperatures ranging from 250 C to 300 C. Higher temperatures (< 300 C) hindered CDRX. This is caused by the fact that nucleation controls CDRX in the aluminum alloy. Dislocation rearrangements result in the formation of low angle boundary networks at moderate strain. The density of lattice dislocations determines the rate of subgrain formation. In addition, at lower temperatures a low energy dislocation structure (LEDS) forms concurrently with the subgrain structure and stabilizes it. The stability of the subgrain structure is very important for the resulting conversion of low angle boundaries into high angle ones with strain by extensive accumulation of mobile lattice dislocations. Increasing temperature in the range of intermediate temperatures suppresses LEDS formation and decreases the lattice dislocation density. This reduces the rate of the subgrain formation process and CDRX. As a result, at T = 400 C no recrystallized grains were found. At T = 475 C, the new grains form due to geometric dynamic recrystallization (GRX).

  18. Suppression of Phospholipase Dγs Confers Increased Aluminum Resistance in Arabidopsis thaliana

    PubMed Central

    Zhao, Jian; Wang, Cunxi; Bedair, Mohamed; Welti, Ruth; W. Sumner, Lloyd; Baxter, Ivan; Wang, Xuemin

    2011-01-01

    Aluminum (Al) toxicity is the major stress in acidic soil that comprises about 50% of the world's arable land. The complex molecular mechanisms of Al toxicity have yet to be fully determined. As a barrier to Al entrance, plant cell membranes play essential roles in plant interaction with Al, and lipid composition and membrane integrity change significantly under Al stress. Here, we show that phospholipase Dγs (PLDγs) are induced by Al stress and contribute to Al-induced membrane lipid alterations. RNAi suppression of PLDγ resulted in a decrease in both PLDγ1 and PLDγ2 expression and an increase in Al resistance. Genetic disruption of PLDγ1 also led to an increased tolerance to Al while knockout of PLDγ2 did not. Both RNAi-suppressed and pldγ1-1 mutants displayed better root growth than wild-type under Al stress conditions, and PLDγ1-deficient plants had less accumulation of callose, less oxidative damage, and less lipid peroxidation compared to wild-type plants. Most phospholipids and glycolipids were altered in response to Al treatment of wild-type plants, whereas fewer changes in lipids occurred in response to Al stress in PLDγ mutant lines. Our results suggest that PLDγs play a role in membrane lipid modulation under Al stress and that high activities of PLDγs negatively modulate plant tolerance to Al. PMID:22163277

  19. Formation of hexagonal AlN nanotowers and layered nanorods by direct nitridation of aluminum

    NASA Astrophysics Data System (ADS)

    Zhang, P. G.; Wang, K. Y.; Liang, Jiandong; Guo, S. M.

    2011-02-01

    Hexagonal AlN nanotowers and layered nanorods with a diameter of hundreds of nanometers and a length of several microns have been successfully synthesized by direct nitridation of aluminum and rice bran mixture compacts in a tube furnace up to 1250 °C under a flow of nitrogen without the addition of extra catalyst. The structure of the nano-AlN products was characterized by XRD and SEM. XRD pattern indicates that the conversion of Al into AlN is complete. The formation of the nanostructures is primarily due to the existence of rich trace elements in the rice bran. The importance of these trace elements and the formation of AlN nanotowers/nanorods have been discussed with the VLS/VS growth mechanisms. The unique morphology of the as-synthesized nanotowers could be useful for investigating fundamental physical phenomena and for fabricating nanodevices.

  20. Experimental study of void formation during aluminum solidification in reduced gravity. Ph.D. Thesis - Toledo Univ.

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis Paul, III

    1993-01-01

    Void formation due to volumetric shrinkage and liquid/vapor reorientation during aluminum solidification was observed in real time by using a radiographic viewing system in normal and reduced gravity. An end-chill directional solidification furnace with water quench was designed and constructed to solidify aluminum samples during the approximately 16 sec of reduced gravity (+/-0.02g) achieved by flying an aircraft through a parabolic trajectory. In the first series of tests the aluminum was contained in a vacuum sealed, pyrolytic boron nitride crucible. An ullage space was present during each test. Void formation was recorded for two cases: a nonwetting system, and a wetting system where wetting occurred between the aluminum and the crucible lid. The void formation in the nonwetting case was similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible. In the wetting case during reduced gravity surface tension caused two voids to form in the top corners of the crucible, but during normal gravity only one large void formed across the top. In the second series of tests the aluminum was contained in a pyrolytic boron nitride crucible that was placed in a stainless steel container and sealed in an environment of argon plus 4 percent hydrogen. An ullage space was present during each test. Void formation was recorded for two cases: a nonwetting system, and a wetting system where wetting occurred between the aluminum and one side wall and the lid. The void for nation in the nonwetting case was similar in normal and reduced gravity, with a single vapor cavity forming at the top of the crucible, although the meniscus became more convex in reduced gravity. In the wetting case the aluminum did not climb up the corners in 1g, and one large symmetric void resulted at the top when the aluminum had solidified. In the wetting case during reduced gravity the molten aluminum was drawn up the wetted wall and partially across the lid by a

  1. Factors Affecting the Nucleation Kinetics of Microporosity Formation in Aluminum Alloy A356

    NASA Astrophysics Data System (ADS)

    Yao, Lu; Cockcroft, Steve; Reilly, Carl; Zhu, Jindong

    2012-03-01

    Metal cleanliness is one of the most critical parameters affecting microporosity formation in aluminum alloy castings. It is generally acknowledged that oxide inclusions in the melt promote microporosity formation by facilitating pore nucleation. In this study, microporosity formation under different casting conditions, which aimed to manipulate the tendency to form and entrain oxide films in small directionally cast A356 samples was investigated. Castings were prepared with and without the aid of argon gas shielding and with a varying pour surface area. Two alloy variants of A356 were tested in which the main difference was Sr content. Porous disc filtration analysis was used to assess the melt cleanliness and identify the inclusions in the castings. The porosity volume fraction and size distribution were measured using X-ray micro-tomography analysis. The measurements show a clear increment in the volume fraction, number density, and pore size in a manner consistent with an increasing tendency to form and entrain oxide films during casting. By fitting the experimental results with a comprehensive pore formation model, an estimate of the pore nucleation population has been made. The model predicts that increasing the tendency to form oxide films increases both the number of nucleation sites and reduces the supersaturation necessary for pore nucleation in A356 castings. Based on the model predictions, Sr modification impacts both the nucleation kinetics and the pore growth kinetics via grain structure.

  2. Short-term aluminum administration in the rat: reductions in bone formation without osteomalacia

    SciTech Connect

    Goodman, W.G.

    1984-05-01

    Aluminum may be a pathogenic factor in dialysis-associated osteomalacia. To study the early effects of Al on bone, cortical bone growth was measured in pair-fed rats given Al and control rats over two consecutive intervals of 28 (period I) and 16 (period II) days, respectively, using tetracycline labeling of bone. Al (2 mg elemental Al per rat) was administered intraperitoneally for 5 days each week, except for the first week of study, when an incremental dose of Al was given. Control rats received saline vehicle only. For the entire 44-day study, bone and matrix formation were reduced from control values in rats given Al. Although bone and matrix formation remained at control levels during period I in rats given Al, both measurements decreased from control values during period II. During Al exposure, bone and matrix apposition at the periosteum were reduced from control levels in period II, but not in period I. Neither osteoid width nor mineralization front width increased from control values in rats given Al. These findings indicate that Al reduces bone and matrix formation early in the course of Al exposure and prior to the development of histologic osteomalacia. Rather than acting as an inhibitor of mineralization, the early effect of Al on bone is the suppression of matrix synthesis. Our results suggest that the state of low bone formation seen in dialysis-associated osteomalacia may be the consequence of a direct toxic effect of Al on the cellular activity of osteoblasts. 29 references, 3 tables.

  3. The role of stress in self-ordered porous anodic oxide formation and corrosion of aluminum

    NASA Astrophysics Data System (ADS)

    Capraz, Omer Ozgur

    The phenomenon of plastic flow induced by electrochemical reactions near room temperature is significant in porous anodic oxide (PAO) films, charging of lithium batteries and stress-corrosion cracking (SCC). As this phenomenon is poorly understood, fundamental insight into flow from our work may provide useful information for these problems. In-situ monitoring of the stress state allows direct correlation between stress and the current or potential, thus providing fundamental insight into technologically important deformation and failure mechanisms induced by electrochemical reactions. A phase-shifting curvature interferometry was designed to investigate the stress generation mechanisms on different systems. Resolution of our curvature interferometry was found to be ten times more powerful than that obtained by state-of-art multiple deflectometry technique and the curvature interferometry helps to resolve the conflicting reports in the literature. During this work, formation of surface patterns during both aqueous corrosion of aluminum and formation of PAO films were investigated. Interestingly, for both cases, stress induced plastic flow controls the formation of surface patterns. Pore formation mechanisms during anodizing of the porous aluminum oxide films was investigated . PAO films are formed by the electrochemical oxidation of metals such as aluminum and titanium in a solution where oxide is moderately soluble. They have been used extensively to design numerous devices for optical, catalytic, and biological and energy related applications, due to their vertically aligned-geometry, high-specific surface area and tunable geometry by adjusting process variables. These structures have developed empirically, in the absence of understanding the process mechanism. Previous experimental studies of anodizing-induced stress have extensively focused on the measurement of average stress, however the measurement of stress evolution during anodizing does not provide

  4. In-situ TEM phase formation in cold rolled aluminum-nickel multilayers

    SciTech Connect

    Sieber, H.; Perepezko, J.H.

    1998-12-31

    Multilayer samples of Nickel and Aluminum with an overall composition of Al-20Ni were prepared by cold rolling of elemental foils. The sample microstructures and phases were characterized by XRD, SEM and TEM/SAED, and the reactive phase formation was then examined by DSC measurements. XRD, SEM and TEM measurements show that the rolling procedure results in a decrease of the Al and Ni layer thicknesses (down to 100 nm in average) and a decrease of the grain size (down to less than 50 nm). No phase formation is observed during the cold rolling procedure. In isochronal DSC scans of the Al-Ni multilayers, the formation of the Al{sub 3}Ni phase was found to be a two step reaction process due to 2-dimensional nucleation and lateral growth and a 3-dimensional phase thickening. While XRD measurements showed Al{sub 3}Ni as the only phase that forms, more detailed TEM investigations of the samples after DSC treatment also showed a small amount of an amorphous Al-Ni phase, formed by a thermally activated solid state amorphization reaction (SSAR). In-situ TEM heating of the amorphous areas under the electron beam in the microscope yielded the crystallization of the amorphous phase to a B2 structure and a growth of the B2 grains up to 100 nm in size.

  5. Structure formation during processing short carbon fiber- reinforced aluminum alloy matrix composites

    NASA Astrophysics Data System (ADS)

    Ciby, S.; Pai, B. C.; Satyanarayana, K. G.; Vaidyan, V. K.; Rohatgi, P. K.

    1993-06-01

    Nickel- and copper-coated, as well as uncoated, short carbon fibers were dispersed in melts of aluminum or aluminum alloys by stirring followed by solidification of composite melts. Microstructural examina-tion of cast composites indicated extensive damage to the surface of the carbon fibers when uncoated carbon fibers were introduced into the melt under the conditions of the present investigation. When nickel- or copper-coated carbon fibers were used to make composites under similar conditions, the fibers generally did not exhibit observable amounts of fiber surface degradation at the interface, except for small islands of an Al4C3 phase. When nickel-coated carbon fibers were used to make composites, the coating reacted with the melt, and NiAl3 intermetallic phase particles were observed in the matrix away from the fibers, indicating a preference for nucleation of NiAl3 away from the fiber surfaces. Under a transmission electron microscope (TEM), the NiAl3 phase was not observed on the surface of carbon fi-bers, except in some regions where the NiAl3 phase engulfed the carbon fibers during growth. When cop-per-coated carbon fibers were used to make composites, the coating reacted with the melt, and particles of CuAl2 intermetallic compound were generally dispersed in the matrix away from the fibers, except for a few locations where the CuAl2 phase was found at the interface under TEM observation. These micro-structures are discussed in terms of nucleation of primary α aluminum and NiAl3 or CuAl2 phases and the interaction between short carbon fibers and these phases during growth while the composite was so-lidifying. Additionally, the role of the reaction between nickel or copper coatings and the melt on struc-ture formation is discussed; some of the differences between the nickel and copper coatings are attributed to the fact that nickel dissolves with an exothermic reaction. The differences between solidification of short fiber composites and particle or fiber

  6. Modeling of porosity formation and feeding flow during casting of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Lin, Zhiping

    Porosity is one of the most important defects in metal casting. To quantitatively predict the porosity formation during casting two numerical models are developed for steel and aluminum alloys respectively. For steel, a multi-phase model is developed that predicts melt pressure, feeding flow, porosity (both microscopic and macroscopic), and riser pipe formation during casting. The phases included in the model are solid, liquid, porosity, and air. An energy equation is solved to determine solid fraction. A multi-phase momentum equation, which is valid everywhere in the solution domain, is derived. A pressure equation is then derived from this momentum equation and a mixture continuity equation developed that accounts for all phases. The partial pressure of a gas species dissolved in the melt is determined using the species concentration, which is found by solving a species conservation equation that accounts for convection. Porosity forms once the gas pressure exceeds the sum of the melt pressure and the capillary pressure. The amount of porosity that forms is determined from the mixture continuity equation. The riser pipe is determined from an air continuity equation. A pore size model, which considers the effects of the solidifying steel microstructure on pore size, is incorporated into the multi-phase model. The multi-phase model is applied to one-dimensional, two-dimensional, and three-dimensional simulations. The results clearly illustrate the basic physical phenomena involved and predict microporosity and macroporosity distributions, as well as a riser pipe. For aluminum alloys a gas microsegregation model is developed to quantitatively predict porosity, coupled with the calculations of the pressure field, feeding flow, and distribution of dissolved gas species throughout the casting. The effects of dendritic and eutectic microstructure on the pore shape and size are considered in a pore size model. The model is applied to one-dimensional simulations of A319

  7. Formation of nanocrystalline h-AlN during mechanochemical decomposition of melamine in the presence of metallic aluminum

    SciTech Connect

    Rounaghi, S.A.; Kiani Rashid, A.R.; Eshghi, H.; Vahdati Khaki, J.

    2012-06-15

    Decomposition of melamine was studied by solid state reaction of melamine and aluminum powders during high energy ball-milling. The milling procedure performed for both pure melamine and melamine/Al mixed powders as the starting materials for various times up to 48 h under ambient atmosphere. The products were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results revealed that Al causes melamine deammoniation at the first stages of milling and further milling process leads to the s-triazine ring degradation while nano-crystallite hexagonal aluminum nitride (h-AlN) was the main solid product. Comparison to milling process, the possibility of the reaction of melamine with Al was also investigated by thermal treatment method using differential scanning calorimeter (DSC) and thermo gravimetric analyzer (TGA). Melamine decomposition occurred by thermal treatment in the range of 270-370 Degree-Sign C, but no reaction between melamine and aluminum was observed. - Graphical Abstract: Mechanochemical reaction of melamine with Al resulted in the formation of nanocrystalline AlN after 7 h milling time Highlights: Black-Right-Pointing-Pointer High energy ball milling of melamine and aluminum results decomposition of melamine with elimination of ammonia. Black-Right-Pointing-Pointer Nano-crystalline AlN was synthesized by the mechanochemical route. Black-Right-Pointing-Pointer Milling process has no conspicuous effect on pure melamine degradation. Black-Right-Pointing-Pointer No reaction takes place by heating melamine and aluminum powder mixture in argon.

  8. Structure and kinetics of formation of interphase layers of synthetic fatty acid aluminum soap at the water/oil interface

    SciTech Connect

    Chalykh, A.E.; Matveev, V.V.; Mityuk, D.Y.; Shal't, S.Y.; Tarasevich, B.N.

    1986-02-01

    The authors investigate the kinetics of formation of interphase layers (IL) at the interface between the phases: a 0.15% solution of aluminum soap of synthetic fatty acids (SFA) (fraction C/sub 17/-C/sub 21/) in n-decane/distilled water. The structure and the morphological properties of IL were investigated by transmission electron spectroscopy. The electron micrographs of the interphase layer of the soap at different stages of its formation show that the formation of a new phase starts with the appearance of small dispersed particles with spherical and fibrillar shapes. The results obtained supplement the authors' concepts about the mechanism of spontaneous microemulsification.

  9. Prediction of Hot Tear Formation in Vertical DC Casting of Aluminum Billets Using a Granular Approach

    NASA Astrophysics Data System (ADS)

    Sistaninia, M.; Drezet, J.-M.; Phillion, A. B.; Rappaz, M.

    2013-09-01

    A coupled hydromechanical granular model aimed at predicting hot tear formation and stress-strain behavior in metallic alloys during solidification is applied to the semicontinuous direct chill casting of aluminum alloy round billets. This granular model consists of four separate three-dimensional (3D) modules: (I) a solidification module that is used for generating the solid-liquid geometry at a given solid fraction, (II) a fluid flow module that is used to calculate the solidification shrinkage and deformation-induced pressure drop within the intergranular liquid, (III) a semisolid deformation module that is based on a combined finite element/discrete element method and simulates the rheological behavior of the granular structure, and (IV) a failure module that simulates crack initiation and propagation. To investigate hot tearing, the granular model has been applied to a representative volume within the direct chill cast billet that is located at the bottom of the liquid sump, and it reveals that semisolid deformations imposed on the mushy zone open the liquid channels due to localization of the deformation at grains boundaries. At a low casting speed, only individual pores are able to form in the widest channels because liquid feeding remains efficient. However, as the casting speed increases, the flow of liquid required to compensate for solidification shrinkage also increases and as a result the pores propagate and coalesce to form a centerline crack.

  10. Polyene Formation Catalyzed by Phosphotungstic Acid and Aluminum Chloride in Thin Films of Poly(Vinyl Alcohol)

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.; Sushko, N. I.; Maly, A. B.

    2016-01-01

    Formation of linear polyenes -(CH=CH) n - during thermal dehydration of thin layers (9-20 μm) of poly(vinyl alcohol) containing phosphotungstic-acid and aluminum-chloride catalysts was investigated. It was found that the concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid increased smoothly with increasing annealing time although the kinetics of the dehydration were independent of the film thickness. The polyene ( n ≥ 8) formation rate in films containing aluminum chloride dropped quickly with decreasing film thickness and increasing annealing time. As a result, long-chain polyenes practically did not form regardless of the annealing time for a film thickness of 11 μm.

  11. A model for the formation of fatigue striations and its relationship with small fatigue crack growth in an aluminum alloy

    SciTech Connect

    Shyam, Amit; Lara-Curzio, Edgar

    2010-01-01

    The fatigue crack growth process involves damage accumulation and crack extension. The two sub-processes that lead to fatigue crack extension were quantified separately in a recent model for small fatigue crack growth applicable to engineering alloys. Here, we report the results of an experimental investigation to assess the assumptions of that model. The fatigue striation formation in an aluminum alloy is modeled and it is verified that the number of cycles required for striation formation is related to the cyclic crack tip opening displacement and that the striation spacing is related to the monotonic crack tip displacement. It is demonstrated that extensive cyclic crack tip plasticity in the aluminum alloy causes a reduction in the magnitude of the slope of the fatigue crack propagation curves. The implications of these results on the fatigue crack propagation lifetime calculations are identified.

  12. Structure and function of ferricyanide in the formation of chromate conversion coatings on aluminum aircraft alloy

    SciTech Connect

    Xia, L.; McCreery, R.L.

    1999-10-01

    Raman and infrared spectroscopy were used to determine the structure of Fe(CN){sup {minus}3}{sub 6} and its reaction products in chromate conversion coatings (CCCs) on AA 2024-T3 aluminum aircraft alloy. In addition, Raman spectroscopy was used to monitor CCC growth rates and their dependence on coating bath composition. The IR and Raman spectra of the air-dried CCC corresponded to those of Berlin green, a Fe{sup +3}-CN-FE{sup +3} polymer, and Fe(CN){sub 6}{sup {minus}3} physisorbed on Cr(OH){sub 3}. No other cyano-containing products were observed. When Fe(CN){sub 6}{sup {minus}3} was excluded from the coating bath, CCC formation rate greatly decreased. In addition, it was observed that Fe(CN){sub 6}{sup {minus}3} could rapidly oxidize AA 2024-T3, and Fe(CN){sub 6}{sup {minus}4} rapidly reduced Cr(VI) in bath conditions. These results indicate a redox mediation action for Fe(CN){sub 6}{sup {minus}3/{minus}4}, which greatly increases the reduction of Cr(VI) to Cr(III) by the alloy. This process is normally quite slow, and redox mediation by Fe(CN){sub 6}{sup {minus}3} is critical to CCC formation. IrCl{sub 6}{sup {minus}3}/{sup {minus}2} could substitute for Fe(CN){sub 6}{sup {minus}3/{minus}4} to produce a chromate film with properties very similar to a conventional CCC. The results establish redox mediation as the mechanism of acceleration of CCC formation, but provide no evidence for any additional role of Fe(CN){sub 6}{sup {minus}3/{minus}4} to produce a chromate film with properties very similar to a conventional CCC. The results establish redox mediation as the mechanism of acceleration of CCC formation, but provide no evidence for any additional role of Fe(CN){sub 6}{sup {minus}3/{minus}4} in corrosion protection.

  13. Experimental study of aluminum-oxalate complexing at 80 °C: Implications for the formation of secondary porosity within sedimentary reservoirs

    NASA Astrophysics Data System (ADS)

    Fein, Jeremy B.

    1991-10-01

    An experimental study of aluminum-oxalate complexing at 80 °C indicates that the presence of oxalate in sedimentary basin fluids may play an important role in creating secondary porosity in reservoir rocks. The solubility of gibbsite was measured as a function of oxalate concentration. Geologically realistic oxalate concentrations were used in order to simulate the aluminum mobilities that occur in reservoir fluids. Although the stoichiometry of the important aluminum-oxalate species cannot be determined from these data, the results are used to quantify the minimum extent of aluminum-oxalate complexing that occurs in solution. Assuming that Al(Ox)33- is the only important aluminum-oxalate complex, the data limit the log of the dissociation constant of Al(Ox)33- to be ≤-16.5. Thermodynamic modeling of aluminum systems with fluids that contain NaCl, acetate, and oxalate illustrates that aluminum-oxalate complexing is much more important than aluminum-acetate complexing, even at relatively low oxalate concentrations and at very high acetate concentrations. In addition, these calculations show that aluminum-oxalate complexing can greatly increase aluminum mobility in formation waters and, therefore, may increase aluminosilicate mineral dissolution within sedimentary basin fluid-rock systems.

  14. Oxalate exudation into the root-tip water free space confers protection from aluminum toxicity and allows aluminum accumulation in the symplast in buckwheat (Fagopyrum esculentum).

    PubMed

    Klug, Benjamin; Horst, Walter J

    2010-07-01

    A better understanding of aluminum (Al) uptake and transport is expected to contribute to unravel the apparent contradiction between Al exclusion and Al accumulation in buckwheat. *We studied the effect of Al supply on the root-tip Al and oxalate concentrations of the apoplastic water free space fluid (WFSF) and the symplast as affected by temperature, oxalate supply and the anion-channel blocker phenylglyoxal (PG). *Aluminum supply rapidly activated the release of oxalate to the WFSF to establish a 1 : 1 Al to oxalate ratio. In the symplast, the Al concentration was 100 times higher than in the external solution, and the Al to oxalate ratio was 1 : 2. Loading and unloading of Al, but not of oxalate, into and from the symplast were reduced at low temperature and are thus under metabolic control. Application of PG reduced the constitutive and the Al-enhanced WFSF oxalate concentrations and enhanced Al-induced root-growth inhibition. Unlike a 1 : 3 Al to oxalate ratio, a 1 : 1 ratio ameliorated only partly Al-induced root-growth inhibition without affecting root-tip Al contents or WFSF Al concentrations. *We present a hypothesis with an Al oxalate (Ox)(+) plasma-membrane transporter in the root cortex and a xylem-loading Al citrate (Cit)(n-) transporter in the xylem parenchyma cells as key elements of Al accumulation in buckwheat.

  15. Factors Leading to the Formation of a Resistive Thin Film at the Bottom of Aluminum Electrolysis Cells

    NASA Astrophysics Data System (ADS)

    Coulombe, Marc-André; Soucy, Gervais; Rivoaland, Loig; Davies, Lynne

    2016-04-01

    Studies on sludge formation in aluminum electrolysis cells are rare and typically do not distinguish the deposits at the center of the cell from those composing the ledge toe because low voltage lost is expected at the center of the cell. However, high amount of sludge in the center leads to the formation of a thin film in an intermediate zone between the ledge toe and this center thick sludge accumulation. Looking at sludge deposits through composition mapping and microstructure analysis coming from four aluminum cells of two different aluminum reduction technologies, major factors leading to a thin resistive film were identified. This includes the formation of a suspension on the top of the thick deposit at the center of the cell, its displacement through magnetohydrodynamic induced movement by the metal pad, and the growth and thickening of a carbide sublayer making the thin film even more resistive. Correlation between thickening of the thin film and cathode voltage drop increase was observed. The postmortem analysis performed on six laboratory experiments was found useful to support different observations made on the industrial cells at lower cost.

  16. Rule of formation of aluminum electroplating layer on Q235 steel.

    PubMed

    Ding, Zhimin; Feng, Qiuyuan; Shen, Changbin; Gao, Hong

    2011-06-01

    Aluminum electroplating layer on Q235 steel in AlCl3-NaCl-KCl molten salt was obtained, and the rule of its nucleation and growth were investigated. The results showed that aluminum electroplating layer formed through nucleating and growing of aluminum particles, and thickened by delaminating growth pattern. At low current density, the morphology of aluminum particles took on flake-like, while at high current density they changed to spherical. The thickness of plating layer increases with increasing current density and electroplating time. The relationship between the plating thickness (δ) and electroplating time (t) or current density (i) can be expressed as δ = 0.28f(137), and δ = 1.1i(1-39).

  17. The Influence of Pyrolythic Reactions on the Aluminum Dross Formation during the Twin Chamber Remelting Process

    NASA Astrophysics Data System (ADS)

    Jaroni, B.; Flerus, B.; Friedrich, B.; Rombach, G.

    After a coated aluminum product has reached the end of life cycle it needs to be recycled in an economical way. State of the art is the thermal removal of the organic fractions by pyrolysis. In modern multi chamber furnaces this step is realized in a separate pre-heating and melting compartment of the furnace. The incidence of aluminum losses can be traced back to the contained organic components, which lead to an aluminum burn off and thus increase dross production. The influence of typical scrap package structures on the de-coating step and the impact of released organic components on the dross quantity are investigated in this work. Lab-scale experiments have shown that the average residence time is too short to complete the pyrolysis. It has to be considered that the pyrolysis continuous while the scrap bale is submerged in the aluminum melt.

  18. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    SciTech Connect

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; Gill, Walt; Donaldson, A. Burl

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics of their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.

  19. Effect of oxide layer formation on deformation of aluminum alloys under fire conditions

    DOE PAGES

    Yilmaz, Nadir; Vigil, Francisco M.; Tolendino, Greg; ...

    2015-05-14

    The purpose of this study is to investigate the structural behavior of aluminum alloys used in the aerospace industry when exposed to conditions similar to those of an accident scenario, such as a fuel fire. This study focuses on the role that the aluminum oxide layer plays in the deformation and the strength of the alloy above melting temperature. To replicate some of the thermal and atmospheric conditions that the alloys might experience in an accident scenario, aluminum rod specimens were subjected to temperatures near to or above their melting temperature in air, nitrogen, and vacuum environments. The characteristics ofmore » their deformation, such as geometry and rate of deformation, were observed. Tests were conducted by suspending aluminum rods vertically from an enclosure. This type of experiment was performed in two different environments: air and nitrogen. The change in environments allowed the effects of the oxide layer on the material strength to be analyzed by inhibiting the growth of the oxide layer. Observations were reported from imaging taken during the experiment showing creep behavior of aluminum alloys at elevated temperatures and time to failure. In addition, an example of tensile load–displacement data obtained in air and vacuum was reported to understand the effect of oxide layer on aluminum deformation and strength.« less

  20. Formation of titanium aluminum nitride layers on AISI D2 steel by nitro-titanizing treatment

    NASA Astrophysics Data System (ADS)

    Cegil, Ozkan; Sen, Saduman

    2012-09-01

    In this study, titanium aluminum nitride coating was realized on AISI D2 steels by nitro-titanizing treatment. Steel samples were nitrided at 575 °C for 8 h in the first step of the coating process, and then titanized by thermo-reactive diffusion method in the powder mixture consisting of ferro-titanium, aluminum, ammonium chloride and alumina at 1000 °C for 2 h. The effects of the aluminum content to the coating bath were investigated. The thickness of the titanium aluminum nitride layer formed on the steel samples ranged from 6.30±0.5 to 7.89±0.34μm, depending on the aluminum content. The average micro-hardness value of the layer was 1468 ± 96 HV0.005 and 2630± 83 HV0.005. The phases formed on the coating layers are TiN, AlTi3N and Ti3Al2N2 which are characterized by XRD. EDS analysis results showed that coating layer includes titanium, aluminum and nitrogen.

  1. Formation and Entrapment of Tris(8-hydroxyquinoline)aluminum from 8-Hydroxyquinoline in Anodic Porous Alumina

    PubMed Central

    Yamaguchi, Shohei; Matsui, Kazunori

    2016-01-01

    The formation and entrapment of tris(8-hydroxyquinoline)aluminum (Alq3) molecules on the surface of anodic porous alumina (APA) immersed in an ethanol solution of 8-hydroxyquinoline (HQ) were investigated by absorption, fluorescence, and Raman spectroscopies. The effects of the selected APA preparation conditions (galvanostatic or potentiostatic anodization method, anodizing current and voltage values, one- or two-step anodizing process, and sulfuric acid electrolyte concentration) on the adsorption and desorption of Alq3 species were examined. Among the listed parameters, sulfuric acid concentration was the most important factor in determining the Alq3 adsorption characteristics. The Alq3 content measured after desorption under galvanostatic conditions was 2.5 times larger than that obtained under potentiostatic ones, regardless of the adsorbed quantities. The obtained results suggest the existence of at least two types of adsorption sites on the APA surface characterized by different magnitudes of the Alq3 bonding strength. The related fluorescence spectra contained two peaks at wavelengths of 480 and 505 nm, which could be attributed to isolated Alq3 species inside nanovoids and aggregated Alq3 clusters in the pores of APA, respectively. The former species were attached to the adsorption sites with higher binding energies, whereas the latter ones were bound to the APA surface more weakly. Similar results were obtained for the Alq3 species formed from the HQ solution, which quantitatively exceeded the number of the Alq3 species adsorbed from the Alq3 solution. Alq3 molecules were formed in the HQ solution during the reaction of HQ molecules with the Al3+ ions in the oxide dissolution zone near the oxide/electrolyte interface through the cracks and the Al3+ ions adsorbed on surface of pore and cracks. In addition, it was suggested that HQ molecules could penetrate the nanovoids more easily than Alq3 species because of their smaller sizes, which resulted in higher

  2. Formation and Entrapment of Tris(8-hydroxyquinoline)aluminum from 8-Hydroxyquinoline in Anodic Porous Alumina.

    PubMed

    Yamaguchi, Shohei; Matsui, Kazunori

    2016-08-24

    The formation and entrapment of tris(8-hydroxyquinoline)aluminum (Alq₃) molecules on the surface of anodic porous alumina (APA) immersed in an ethanol solution of 8-hydroxyquinoline (HQ) were investigated by absorption, fluorescence, and Raman spectroscopies. The effects of the selected APA preparation conditions (galvanostatic or potentiostatic anodization method, anodizing current and voltage values, one- or two-step anodizing process, and sulfuric acid electrolyte concentration) on the adsorption and desorption of Alq₃ species were examined. Among the listed parameters, sulfuric acid concentration was the most important factor in determining the Alq₃ adsorption characteristics. The Alq₃ content measured after desorption under galvanostatic conditions was 2.5 times larger than that obtained under potentiostatic ones, regardless of the adsorbed quantities. The obtained results suggest the existence of at least two types of adsorption sites on the APA surface characterized by different magnitudes of the Alq₃ bonding strength. The related fluorescence spectra contained two peaks at wavelengths of 480 and 505 nm, which could be attributed to isolated Alq₃ species inside nanovoids and aggregated Alq₃ clusters in the pores of APA, respectively. The former species were attached to the adsorption sites with higher binding energies, whereas the latter ones were bound to the APA surface more weakly. Similar results were obtained for the Alq₃ species formed from the HQ solution, which quantitatively exceeded the number of the Alq₃ species adsorbed from the Alq₃ solution. Alq₃ molecules were formed in the HQ solution during the reaction of HQ molecules with the Al(3+) ions in the oxide dissolution zone near the oxide/electrolyte interface through the cracks and the Al(3+) ions adsorbed on surface of pore and cracks. In addition, it was suggested that HQ molecules could penetrate the nanovoids more easily than Alq₃ species because of their smaller

  3. Cage Structure Formation of Singly Doped Aluminum Cluster Cations Al n TM + ( TM = Ti, V, Cr)

    NASA Astrophysics Data System (ADS)

    Lang, Sandra M.; Claes, Pieterjan; Neukermans, Sven; Janssens, Ewald

    2011-09-01

    Structural information on free transition metal doped aluminum clusters, Al n TM + ( TM = Ti, V, Cr), was obtained by studying their ability for argon physisorption. Systematic size ( n = 5 - 35) and temperature ( T = 145 - 300 K) dependent investigations reveal that bare Al n + clusters are inert toward argon, while Al n TM + clusters attach one argon atom up to a critical cluster size. This size is interpreted as the geometrical transition from surface-located dopant atoms to endohedrally doped aluminum clusters with the transition metal atom residing in an aluminum cage. The critical size, n crit , is found to be surprisingly large, namely n crit = 16 and n crit = 19 - 21 for TM = V, Cr, and TM = Ti, respectively. Experimental cluster-argon bond dissociation energies have been derived as function of cluster size from equilibrium mass spectra and are in the 0.1-0.3 eV range.

  4. On the formation of aliphatic polycarbonates from epoxides with chromium(III) and aluminum(III) metal-salen complexes.

    PubMed

    Luinstra, Gerrit A; Haas, Gerhard R; Molnar, Ferenc; Bernhart, Volker; Eberhardt, Robert; Rieger, Bernhard

    2005-10-21

    A DFT-based description is given of the CO2/epoxide copolymerization with a catalyst system consisting of metal (chromium, iron, titanium, aluminum)-salen complexes (salen = N,N'-bis(3,5-di-tert-butylsalicyliden-1,6-diaminophenyl) in combination with either chloride, acetate, or dimethylamino pyridine (DMAP) as external nucleophile. Calculations indicate that initiation proceeds through nucleophilic attack at a metal-coordinated epoxide, and the most likely propagation reaction is a bimolecular process in which a metal-bound nucleophile attacks a metal-bound epoxide. Carbon dioxide insertion occurs at a single metal center and is most likely the rate-determining step at low pressure. The prevalent chain terminating/degradation-the so-called backbiting, a reaction leading to formation of cyclic carbonate from the polymer chain-would involve attack of a carbonate nucleophile rather than an alkoxide at the last unit of the growing chain. The backbiting of a free carbonato chain end is particularly efficient. Anion dissociation from six-coordinate aluminum is appreciably easier than from chromium-salen complexes, indicating the reason why in the former case cyclic carbonate is the sole product. Experimental data were gathered for a series of chromium-, aluminum-, iron-, and zinc-salen complexes, which were used in combination with external nucleophiles like DMAP and mainly (tetraalkyl ammonium) chloride/acetate. Aluminum complexes transform PO (propylene oxide) and CO2 to give exclusively propylene carbonate. This is explained by rapid carbonate anion dissociation from a six-coordinate complex and cyclic formation. CO2 insertion or nucleophilic attack of an external nucleophile at a coordinated epoxide (at higher CO2 pressure) are the rate-determining steps. Catalysis with [Cr(salen)(acetate/chloride)] complexes leads to the formation of both cyclic carbonate and polypropylene carbonate with various quantities of ether linkages. The dependence of the activity and

  5. The utility of the matrix format for surgical morbidity and mortality conference.

    PubMed

    Bhalla, Varun K; Boone, Luke; Lewis, Frank; Gucwa, Angela L; Kruse, E James

    2015-05-01

    With the limitations posed by increasing work hour restrictions, surgical residency programs are focusing more on maximizing the educational benefit of their conferences. The Morbidity and Mortality (M&M) conference serves as a forum to discuss adverse events and patient care improvement using evidence-based medicine. The matrix format (MF) is an enhancement to the traditional format (TF), focusing on the case selection process and a postconference newsletter reiterating the relevant literature review and discussion points. Our institution adopted the MF to evaluate both its short- and long-term educational values. Surveys were distributed to residents and faculty within the Department of General Surgery to assess their interest and satisfaction, perception of educational value, and efficiency with the MF compared with the TF. Responses were obtained from 22/22 (100%) residents for the TF and 11/23 (48%) for the MF. Faculty responses were 19/19 (100%) and 9/16 (56%), respectively. Reasons for an overall decreased response with the MF were not investigated further, as participation was strictly voluntary. Our results confirmed an overall approval of the MF by both residents and faculty. Faculty reported an improved efficiency of the conference (P < 0.039), encompassing improved content and presentation quality. Residents reported an improved overall interest and satisfaction with the MF (P < 0.001) as well as an improvement in the educational value (P < 0.007). Residents spent less time preparing presentations and reported learning greater educational benefit to the conference when preparing their own presentations (P < 0.001). In conclusion, the MF resulted in a greater overall satisfaction for residents and attending surgeons with an increased investment by the audience and overall improvement in perceived educational benefit.

  6. Effect of nonsolvent on the formation of polymer nanomaterials in the nanopores of anodic aluminum oxide templates.

    PubMed

    Lee, Chih-Wei; Wei, Tzu-Hui; Chang, Chun-Wei; Chen, Jiun-Tai

    2012-08-28

    We study the effect of nonsolvent on the formation of polymer nanomaterials in the nanopores of porous templates. Water (nonsolvent) is added into a poly (methyl methacrylate) (PMMA) solution in dimethylformamide (DMF) confined in the nanopores of an anodic aluminum oxide (AAO) template. Water forms a wetting layer on the pore wall and causes the PMMA solution to be isolated in the center of the nanopore, resulting in the formation of PMMA nanospheres or nanorods after the solvent is evaporated. The formation of the polymer nanomaterials induced by nonsolvent is found to be driven by the Rayleigh-instability-type transformation. Without adding the nonsolvent, PMMA chains precipitate on the walls of the nanopores after the solvent is evaporated, and PMMA nanotubes are obtained.

  7. One-Component Aluminum(heteroscorpionate) Catalysts for the Formation of Cyclic Carbonates from Epoxides and Carbon Dioxide.

    PubMed

    Martínez, Javier; Castro-Osma, José A; Alonso-Moreno, Carlos; Rodríguez-Diéguez, Antonio; North, Michael; Otero, Antonio; Lara-Sánchez, Agustín

    2017-03-22

    New neutral and zwitterionic chiral NNO-donor scorpionate ligands 1 and 2 were designed to obtain new mononuclear and dinuclear NNO-heteroscorpionate aluminum complexes. Reaction of 1 with [AlR3 ] (R=Me, Et) in a 1:1 or 1:2 molar ratio afforded the neutral mononuclear alkyl complexes [AlR2 (κ(2) -bpzappe)] {R=Me (3), Et (4); bpzappeH=2,2-bis(3,5-dimethylpyrazol-1-yl)-1-[4-(dimethylamino)phenyl]-1-phenylethanol} and bimetallic complexes [{AlR2 (κ(2) -bpzappe)}(μ-O){AlR3 }] [R=Me (5), Et (6)]. By reaction of complexes 3-6 with PhCH2 Br, mononuclear and dinuclear cationic aluminum complexes [AlR2 (κ(2) -bbpzappe)]Br {R=Me (7), Et (8); bbpzappeH=N-benzyl-4-[2,2-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1-hydroxy-1-phenylethyl]-N,N-dimethylbenzenaminium bromide} and [{AlR2 (κ(2) -bbpzappe)}(μ-O){AlR3 }]Br [R=Me (9), Et (10)] were synthesized. Both neutral aluminum complexes in the presence of Bu4 NBr and cationic aluminum complexes were investigated as catalysts for cyclic carbonate formation from epoxides and carbon dioxide. Amongst them, complex 10 was found to be an efficient one-component catalyst for the synthesis of cyclic carbonates from both monosubstituted and internal epoxides and was shown to have broad substrate scope.

  8. Influence of Aluminum on the Formation Behavior of Zn-Al-Fe Intermetallic Particles in a Zinc Bath

    NASA Astrophysics Data System (ADS)

    Park, Joo Hyun; Park, Geun-Ho; Paik, Doo-Jin; Huh, Yoon; Hong, Moon-Hi

    2012-01-01

    The shape, size, and composition of dross particles as a function of aluminum content at a fixed temperature were investigated for aluminum added to the premelted Zn-Fe melt simulating the hot-dip galvanizing bath by a sampling methodology. In the early stage, less than 30 minutes after Al addition, local supersaturation and depletion of the aluminum concentration occurred simultaneously in the bath, resulting in the nucleation and growth of both Fe2Al5Zn x and FeZn13. However, the aluminum was homogenized continuously as the reaction proceeded, and fine and stable FeZn10Al x formed after 30 minutes. An Al-depleted zone (ADZ) mechanism was newly proposed for the "η→η+ζ→δ" phase transformations. The ζ phase bottom dross partly survived for a relatively long period, i.e., 2 hours in this work, whereas the η phase disappeared after 30 minutes. In the early stage of dross formation, both Al-free large particles as well as high-Al tiny particles were formed. The dross particle size decreased slightly with increased reaction time before reaching a plateau. The opposite tendency was observed when the Al content was 0.130 mass pct; with a relatively high Al content, the nucleation of tiny η phase dross was significantly enhanced because of the high degree of supersaturation. This unstable η phase dissolved continuously and underwent simple transformation to the stable δ phase. The relationship between nucleation potential and supersaturation ratio of species is discussed based on the thermodynamics of classical nucleation theory.

  9. Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.

    PubMed

    Wang, Wendong; Song, Shan; Zhang, Xiaoni; Mitchell Spear, J; Wang, Xiaochang; Wang, Wen; Ding, Zhenzhen; Qiao, Zixia

    2014-07-01

    Observations of aluminum containing sediments/scales formed within the distribution pipes have been reported for several decades. In this study, the effect of Ni(2+) on the formation and transformation processes of aluminum hydroxide sediment in a simulated drinking water distribution system were investigated using X-ray diffraction spectrum (XRD), Fourier transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and thermodynamic calculation methods. It was determined that the existence of Ni(2+) had notable effects on the formation of bayerite. In the system without Ni(2+) addition, there was no X-ray diffraction signal observed after 400 d of aging. The presence of Ni(2+), however, even when present in small amounts (Ni/Al=1:100) the formation of bayerite would occur in as little as 3d at pH 8.5. As the molar ratio of Ni/Al increase from 1:100 to 1:10, the amount of bayerite formed on the pipeline increased further; meanwhile, the specific area of the pipe scale decreased from 160 to 122 m(2)g(-1). In the system with Ni/Al molar ratio at 1:3, the diffraction spectrum strength of bayerite became weaker, and disappeared when Ni/Al molar ratios increased above 1:1. At these highs Ni/Al molar ratios, Ni5Al4O11⋅18H2O was determined to be the major component of the pipe scale. Further study indicated that the presence of Ni(2+) promoted the formation of bayerite and Ni5Al4O11⋅18H2O under basic conditions. At lower pH (6.5) however, the existence of Ni(2+) had little effect on the formation of bayerite and Ni5Al4O11⋅18H2O, rather the adsorption of amorphous Al(OH)3 for Ni(2+) promoted the formation of crystal Ni(OH)2.

  10. Influence of the surface pre-treatment of aluminum on the processes of formation of cerium oxides protective films

    NASA Astrophysics Data System (ADS)

    Andreeva, R.; Stoyanova, E.; Tsanev, A.; Stoychev, D.

    2016-03-01

    It is known that there is special interest in the contemporary investigations on conversion treatment of aluminum aimed at promoting its corrosion stability, which is focused on electrolytes on the basis of salts of metals belonging to the group of rare-earth elements. Their application is especially attractive, as it enables a successful substitution of the presently applied highly efficient, but at the same time toxic Cr6+-containing electrolytes. The present paper presents a study on the influence of the preliminary alkaline activation and acidic de-oxidation of the aluminum surface on the processes of immersion formation of protective cerium oxides films on Al 1050. The results obtained show that their deposition from simple electrolytes (containing only salts of Ce3+ ions) on the Al surface, treated only in alkaline solution, occurs at a higher rate, which leads to preparing thicker oxide films having a better protective ability. In the cases when the formation of oxide films is realized in a complex electrolyte (containing salts of Ce3+ and Cu2+ ions), better results are obtained with respect to the morphology and protective action of cerium oxides film on samples that have been consecutively activated in alkaline solution and deoxidized in acidic solution. Electrochemical investigations were carried out in a model corrosion medium (0.1 M NaCl); it was shown that the cerium protective films, deposited by immersion, have a cathodic character with regard to the aluminum support and inhibit the occurrence of the depolarizing corrosion process -- the reaction of oxygen reduction.

  11. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates

    NASA Astrophysics Data System (ADS)

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-04-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film PAA/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.

  12. A simple model for predicting aluminum bound phosphorus formation and internal loading reduction in lakes after aluminum addition to lake sediment.

    PubMed

    Huser, Brian J; Pilgrim, Keith M

    2014-04-15

    The conversion of mobile phosphorus (P) to aluminum bound P (Al-P) after addition of Al to over 300 sub-samples from 35 sediment cores collected from 20 lakes in the upper Midwest, United States was investigated in this study. Consistent relationships between mobile P reduction and Al-P formation were detected across a broad range of mobile sediment P contents (0.04-2.8 g P m(-2) cm(-1) or 0.083-2.8 mg P g(-1)DW) and lake types. The conversion of mobile P to Al-P was dependent on the initial mobile sediment P content and the amount of Al added to the sediment. An empirical model was then developed to predict the formation of Al-P based on the amount of Al added relative to the initial mass of mobile P in the sediment. The results were compared to sediment collected from an Al treated lake and good agreement was found between the model and in-situ changes to sediment P fractions caused by Al treatment. The model developed in this study, unlike previous models with extreme, singular endpoints, allows for a continuum of estimates for mobile P conversion to Al-P, along with efficiency of P binding by Al, as Al dose varies. Model results can be used in conjunction with mobile sediment P based predictions for internal P loading to calculate an Al dose required to meet internal phosphorus loading goals for lake management and restoration without the need for expensive, time consuming Al additions to sediment.

  13. Microlasers based on high-Q rare-earth-doped aluminum oxide resonators on silicon (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Bradley, Jonathan D. B.; Su, Zhan; Frankis, Henry C.; Magden, Emir Salih; Li, Nanxi; Byrd, Matthew; Purnawirman, Purnawirman; Shah Hosseini, Ehsan; Adam, Thomas N.; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R.

    2017-02-01

    One of the key challenges in the field of silicon photonics remains the development of compact integrated light sources. In one approach, rare-earth-doped glass microtoroid and microdisk lasers have been integrated on silicon and exhibit ultra-low thresholds. However, such resonator structures are isolated on the chip surface and require an external fiber to couple light to and from the cavity. Here, we review our recent work on monolithically integrated rare-earth-doped aluminum oxide microcavity lasers on silicon. The microlasers are enabled by a novel high-Q cavity design, which includes a co-integrated silicon nitride bus waveguide and a silicon dioxide trench filled with rare-earth-doped aluminum oxide. In passive (undoped) microresonators we measure internal quality factors as high as 3.8 × 105 at 0.98 µm and 5.7 × 105 at 1.5 µm. In ytterbium, erbium, and thulium-doped microcavities with diameters ranging from 80 to 200 µm we show lasing at 1.0, 1.5 and 1.9 µm, respectively. We observe sub-milliwatt lasing thresholds, approximately 10 times lower than previously demonstrated in monolithic rare-earth-doped lasers on silicon. The entire fabrication process, which includes post-processing deposition of the gain medium, is silicon-compatible and allows for integration with other silicon-based photonic devices. Applications of such rare earth microlasers in communications and sensing and recent design enhancements will be discussed.

  14. Formation of linear polyenes in poly(vinyl alcohol) films catalyzed by phosphotungstic acid, aluminum chloride, and hydrochloric acid

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.; Sushko, N. I.; Malyi, A. B.

    2016-07-01

    Formation of linear polyenes-(CH=CH)n-via acid-catalyzed thermal dehydration of polyvinyl alcohol in 9- to 40-µm-thick films of this polymer containing hydrochloric acid, aluminum chloride, and phosphotungstic acid as dehydration catalysts was studied by electronic absorption spectroscopy. The concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid is found to monotonically increase with the duration of thermal treatment of films, although the kinetics of this process is independent of film thickness. In films containing hydrochloric acid and aluminum chloride, the formation rate of polyenes with n ≥ 8 rapidly drops as film thickness decreases and the annealing time increases. As a result, at a film thickness of less than 10-12 µm, long-chain polyenes are not formed at all in these films no matter how long thermal duration is. The reason for this behavior is that hydrochloric acid catalyzing polymer dehydration in these films evaporates from the films during thermal treatment, the evaporation rate inversely depending on film thickness.

  15. Effect of Thermal Cycle on the Formation of Intermetallic Compounds in Laser Welding of Aluminum-Steel Overlap Joints

    NASA Astrophysics Data System (ADS)

    Fan, J.; Thomy, C.; Vollertsen, F.

    The intermetallic compound (IMC) (or intermetallic phase layer) has a significant influence on the mechanical properties ofjoints between dissimilar metals obtained by thermal processes such as laser welding. Its formation is basically affected by thermal cycles in the joining or contact zone, where the IMC is formed. Within this study, the influence of the thermal cycle on the formation of the IMC during laser welding of an aluminum-steel (Al99.5-DC01) overlap joint was investigated. The temperature was measured directly by a thermocouple, and the weld seam was analyzed by scanning electron microscope (SEM). The influence of peak temperature, cooling time and the integral of the thermal cycle on the thickness of the IMC was identified and discussed. It was identified that cooling time has the biggest influence on the thickness of the IMC.

  16. Copper stabilization via spinel formation during the sintering of simulated copper-laden sludge with aluminum-rich ceramic precursors.

    PubMed

    Tang, Yuanyuan; Chui, Stephen Sin-Yin; Shih, Kaimin; Zhang, Lingru

    2011-04-15

    The feasibility of incorporating copper-laden sludge into low-cost ceramic products, such as construction ceramics, was investigated by sintering simulated copper-laden sludge with four aluminum-rich ceramic precursors. The results indicated that all of these precursors (γ-Al(2)O(3), corundum, kaolinite, mullite) could crystallochemically stabilize the hazardous copper in the more durable copper aluminate spinel (CuAl(2)O(4)) structure. To simulate the process of copper transformation into a spinel structure, CuO was mixed with the four aluminum-rich precursors, and fired at 650-1150 °C for 3 h. The products were examined using powder X-ray diffraction (XRD) and scanning electron microscopic techniques. The efficiency of copper transformation among crystalline phases was quantitatively determined through Rietveld refinement analysis of the XRD data. The sintering experiment revealed that the optimal sintering temperature for CuAl(2)O(4) formation was around 1000 °C and that the efficiency of copper incorporation into the crystalline CuAl(2)O(4) structure after 3 h of sintering ranged from 40 to 95%, depending on the type of aluminum precursor used. Prolonged leaching tests were carried out by using acetic acid with an initial pH value of 2.9 to leach CuO and CuAl(2)O(4) samples for 22 d. The sample leachability analysis revealed that the CuAl(2)O(4) spinel structure was more superior to stabilize copper, and suggested a promising and reliable technique for incorporating copper-laden sludge or its incineration ash into usable ceramic products. Such results also demonstrated the potential of a waste-to-resource strategy by using waste materials as part of the raw materials with the attainable temperature range used in the production of ceramics.

  17. On the role of magnesium and silicon in the formation of alumina from aluminum alloys by means of DIMOX processing

    SciTech Connect

    Yang, L.; Zhu, D.; Xu, C.; Zhang, J.; Zhang, J.

    1996-08-01

    This article deals with the reaction mechanisms of the DIMOX (Directed Melt Oxided) processing of aluminum alloys. An orthogonalized experimental procedure was introduced to stipulate the effects of the reaction temperature, reaction time, and additional metallic elements, magnesium and silicon, on the oxidation process of aluminum alloys. Emphasis is placed on the distribution of magnesium and silicon in the products so that the behaviors of these two crucial elements for the formation of alumina from directed oxidation of aluminum alloys could be revealed. Alterative methods, including optical and scanning electron microscopy (SEM), electron probing, and wave spectrum analysis were applied to specify the microstructure characters of the products and locate the position of both magnesium and silicon in the reaction products. Judged by the weight gain after reaction, the results indicated that the temperature is the most influential factor in controlling the oxidation kinetics. Both magnesium and silicon are rather concentrated in specific regions than homogeneously distributed in the whole products. The contents of magnesium and silicon in the surface region are not as high as expected, and most of the magnesium being concentrated in the region directly neighboring the bulky metals and most of the Si in the residual bulky metals, although the contents of these two elements in the surface region are a little higher than the regions next to the surface. These characteristics, combined with other investigations, suggest that the decisive role of the slight amount of magnesium and silicon in the nucleation and growth of Al{sub 2}O{sub 3} could be explained by the proposed circulated reaction.

  18. On the role of magnesium and silicon in the formation of alumina from aluminum alloys by means of DIMOX processing

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Zhu, Degui; Xu, Changqing; Zhang, Jun; Zhang, Jian

    1996-08-01

    This article deals with the reaction mechanisms of the DIMOX (Directed Melt Oxided) processing of aluminum alloys. An orthogonalized experimental procedure was introduced to stipulate the effects of the reaction temperature, reaction time, and additional metallic elements, magnesium and silicon, on the oxidation process of aluminum alloys. Emphasis is placed on the distribution of magnesium and silicon in the products so that the behaviors of these two crucial elements for the formation of alumina from directed oxidation of aluminum alloys could be revealed. Alterative methods, including optical and scanning electron microscopy (SEM), electron probing, and wave spectrum analysis were applied to specify the microstructure characters of the products and locate the position of both magnesium and silicon in the reaction products. Judged by the weight gain after reaction, the results indicated that the temperature is the most influential factor in controlling the oxidation kinetics. Silicon is more effective than magnesium in accelerating the process, although magnesium is indispensable for the process to take place. While judged by the morphology of the reaction products, an excessive amount of silicon is harmful to the DIMOX process in that the final products consist of a large amount of porosity. Both magnesium and silicon are rather concentrated in specific regions than homogeneously distributed in the whole products. The contents of magnesium and silicon in the surface region are not as high as expected, with most of the magnesium being concentrated in the region directly neighboring the bulky metals and most of the Si in the residual bulky metals, although the contents of these two elements in the surface region are a little higher than the regions next to the surface. These characteristics, combined with other investigations, suggest that the decisive role of the slight amount of magnesium and silicon in the nucleation and growth of Al2O3 could be explained by

  19. Effect of aluminum on the formation of silver metal quantum dots in sol-gel derived alumino-silicate glass film.

    PubMed

    Kim, Bok Hyeon; Son, Dong Hoon; Ju, Seongmin; Jeong, Chaehwan; Boo, Seongjae; Kim, Cheol Jin; Hanl, Won-Taek

    2006-11-01

    The effect of aluminum incorporation on silver metal quantum dots formation in the alumino-silicate glass film processed by sol-gel process was investigated. The sol-gel derived glass was coated onto the silica glass plate by spin coating with the mixture solution of tetraethyl orthosilicate (TEOS), C2H5OH, H2O, AgNO3, Al(NO3)3. 39H2O, and HNO3 with the molar ratios of Ag/Si = 0.12 and Al/Si varying from 0 to 0.12. The formation of the silver metal quantum dots was confirmed by the measurements of the UV/VIS optical spectra, the X-ray diffraction patterns, and the transmission electron microscope images. While the radius of silver metal quantum dots increased with the increase of aluminum concentration, the concentration of the silver metal quantum dots decreased. The formation of the silver metal quantum dots was found strongly suppressed by incorporation of aluminum ions in the glass. The change in the glass structure due to the aluminum incorporation was investigated by the analysis of the Raman spectra. The silver ions in the glass contributed to form stable (Al:Ag)O4 tetrahedra by pairing with aluminum ions and thus clustering of silver metal quantum dots was hindered.

  20. Prevention of PCDD/F formation and minimization of their emission at the stack of a secondary aluminum casting plant.

    PubMed

    Pitea, Demetrio; Bortolami, Michele; Collina, Elena; Cortili, Gabriele; Franzoni, Francesco; Lasagni, Marina; Piccinelli, Elsa

    2008-10-01

    Results of an extensive 5 year study on a full-scale plant with the specific aim to investigate polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzo furan (PCDF) formation and release in a secondary aluminum casting plant are reported. PCDD and PCDF concentrations were evaluated for all the gaseous and solid streams (no liquid stream was present) as well as for the flue gas upstream and downstream of every single unit of the flue gas cleaning system. The study highlights PCDD and PCDF formation particularly in the narrow 320-360 degrees C range. To prevent formation reactions and/or minimize PCDD and PCDF concentration at the stack, effects of the fabric filter substitution, a quenching chamber and a postcombustor installation together with working conditions are investigated. The flue gas cleaning system results in PCDD and PCDF emission at stack of 0.1-0.2 ng I-TEQ/N m3 and in a mass flow of 250-550 nmol/h. The total PCDD and PCDF release into the environment is 0.06 g I-TEQ/yr and the corresponding emission factor, 0.35 microg I-TEQ/ton. It is shown that the global effects of the technological innovation on the reaction mechanisms are the prevention of PCDD/F formation by de novo synthesis and the minimization of their emission.

  1. The formation and evolution of the core-corona structure in the electrical explosion of aluminum wire in vacuum: experimental and numerical investigations

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Shi, Zongqian; Shi, Yuanjie

    2017-08-01

    Experimental and numerical investigations on the formation and evolution of the core-corona structure in the electrical explosion of aluminum wire in vacuum are presented. In the experiments of aluminum wire explosion, shadowgraphy, interferometry and schlieren optical diagnostics are constructed with a laser probe to study the morphological evolution and distribution of the core and corona. A set of computational models with cold start conditions, consisting of a thermodynamic calculation and magnetohydrodynamic model combined with a semi-empirical equation of state and transport coefficients, are established to reproduce the behavior of the electrical explosion of aluminum wire. The radial profiles of the density, temperature, current density and magnetic field, addressing the physical scenario of the formation and evolution of the core-corona structure are analyzed. The numerical results are also compared with relevant experimental data.

  2. Experimental study to validate a model of hillock{close_quote}s formation in aluminum thin films

    SciTech Connect

    Genin, F.Y.; Siekhaus, W.J.

    1996-04-01

    The growth of holes and hillocks in thin films has been reported extensively and for a multitude of film{endash}substrate systems. A recently developed model [F. Y. G{acute e}nin, J. Appl. Phys. {bold 77}, 5130 (1995)] which analyzes the formation of a ridge at a traveling grain boundary due to stress and capillarity driving forces provides a quantitative description of the growth of the hillocks. In order to test the model, the surface morphology of aluminum thin films deposited on oxidized silicon substrates and annealed at 450{degree}C in argon is investigated; the profiles of thermal hillocks are measured by atomic force microscopy. The comparison shows excellent agreement between modeled and experimental profiles. {copyright}{ital 1996 American Institute of Physics.}

  3. The formation of iron aluminides on aluminum surface by using a Q-switched Nd:YAG laser

    SciTech Connect

    Bidin, Noriah; Al-Wafi, Yusef A.

    2014-03-05

    The formation and growth of Fe based aluminum diffusion layers at the Fe-Al interface have been investigated to improve the surface hardness. The diffusion of Fe into Al has been accomplished by focusing a Q-switched Nd:YAG laser on the modified surface. The variety of the layer depth is achieved based on the type of heating and quenching media. Microstructural characterization and mechanical properties of the modified surface were carried out via gas discharge spectrometer GDS, X-Ray diffraction (XRD), Scanning electron microscope (SEM), and Vickers Hardness tester. The results indicate that hardness at the interface of Fe-Al layer is increased. The optimum hardness achieved as 93 HV at corresponding critical energy density of 438 Jcm{sup −2}.

  4. Characterization of monolayer formation on aluminum-doped zinc oxide thin films.

    PubMed

    Rhodes, Crissy L; Lappi, Simon; Fischer, Daniel; Sambasivan, Sharadha; Genzer, Jan; Franzen, Stefan

    2008-01-15

    The optical and electronic properties of aluminum-doped zinc oxide (AZO) thin films on a glass substrate are investigated experimentally and theoretically. Optical studies with coupling in the Kretschmann configuration reveal an angle-dependent plasma frequency in the mid-IR for p-polarized radiation, suggestive of the detection of a Drude plasma frequency. These studies are complemented by oxygen depletion density functional theory studies for the calculation of the charge carrier concentration and plasma frequency for bulk AZO. In addition, we report on the optical and physical properties of thin film adlayers of n-hexadecanethiol (HDT) and n-octadecanethiol (ODT) self-assembled monolayers (SAMs) on AZO surfaces using reflectance FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Our characterization of the SAM deposition onto the AZO thin film reveals a range of possible applications for this conducting metal oxide.

  5. Characterization of Monolayer Formation on Aluminum-Doped Zinc Oxide Thin Films

    SciTech Connect

    Rhodes,C.; Lappi, S.; Fischer, D.; Sambasivan, S.; Genzer, J.; Franzen, S.

    2008-01-01

    The optical and electronic properties of aluminum-doped zinc oxide (AZO) thin films on a glass substrate are investigated experimentally and theoretically. Optical studies with coupling in the Kretschmann configuration reveal an angle-dependent plasma frequency in the mid-IR for p-polarized radiation, suggestive of the detection of a Drude plasma frequency. These studies are complemented by oxygen depletion density functional theory studies for the calculation of the charge carrier concentration and plasma frequency for bulk AZO. In addition, we report on the optical and physical properties of thin film adlayers of n-hexadecanethiol (HDT) and n-octadecanethiol (ODT) self-assembled monolayers (SAMs) on AZO surfaces using reflectance FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Our characterization of the SAM deposition onto the AZO thin film reveals a range of possible applications for this conducting metal oxide.

  6. Formation of particulate Fe-Al films by selective oxidation of aluminum

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seung Chan

    2013-09-01

    Fe-5wt%Al films were RF-sputtered and annealed in an atmosphere of hydrogen and water vapor mixture at 1173 K for up to 200 min in order to selectively oxidize aluminum. As the annealing time increased, the morphology of the films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. Thermodynamics simulation was performed to determine the ideal conditions for this process. Temperatures exceeding 1073 K are necessary to prevent iron from oxidation confirmed by both the depth profile in XPS and magnetic moment increment in VSM. Annealing the films in an atmosphere with a very low dew point of 77 K did not make the films become particulate. New findings are expected to be applied to the thin film inductors for GHz application as well as to manufacturing process of nanoparticles.

  7. Formation of layered Fe(II)-Al(III)-hydroxides during reaction of Fe(II) with aluminum oxide.

    PubMed

    Elzinga, Evert J

    2012-05-01

    The reactivity of aqueous Fe(II) with aluminum oxide in anoxic solutions was investigated with batch kinetic experiments combined with Fe K edge X-ray absorption spectroscopy measurements to characterize Fe(II) sorption products. Formation of Fe(II)-Al(III)-layered double hydroxides with an octahedral sheet structure similar to nikischerite (NaFe(II)(6) Al(3)(SO(4))(2)(OH)(18) (H(2)O)(12)) was observed within a few hours during sorption at pH 7.5 and aqueous Fe(II) concentrations of 1-3 mM. These Fe(II) phases are composed of brucite-like Fe(II)(OH)(2) sheets with partial substitution of Al(III) for Fe(II), charge balanced by anions coordinated along the basal planes. Their fast rate of formation suggests that these previously unrecognized Fe(II) phases, which are structurally and compositionally similar to green rust, may be an important sink of Fe(II) in suboxic and anoxic geochemical environments, and impact the fate of structurally compatible trace metals, such as Co(II), Ni(II), and Zn(II), as well as redox-reactive species including Cr(VI) and U(VI). Further studies are required to assess the thermodynamics, formation kinetics, and stability of these Fe(II) minerals under field conditions.

  8. Australian Family Research Conference Proceedings (Canberra, Australia, November 23-25, 1983). Volume I: Family Formation, Structure, Values.

    ERIC Educational Resources Information Center

    Institute of Family Studies, Melbourne (Australia).

    First in a series of seven volumes containing the proceedings of the 1983 Australian Family Research Conference, this publication deals with the formation, structure, and values of family life in Australia. Papers and authors included are: "Priorities in Family Research and Family Law" (Gareth Evans), "The Baby Boom Generation as…

  9. Australian Family Research Conference Proceedings (Canberra, Australia, November 23-25, 1983). Volume I: Family Formation, Structure, Values.

    ERIC Educational Resources Information Center

    Institute of Family Studies, Melbourne (Australia).

    First in a series of seven volumes containing the proceedings of the 1983 Australian Family Research Conference, this publication deals with the formation, structure, and values of family life in Australia. Papers and authors included are: "Priorities in Family Research and Family Law" (Gareth Evans), "The Baby Boom Generation as…

  10. Role of low-energy ion irradiation in the formation of an aluminum germanate layer on a germanium substrate by radical-enhanced atomic layer deposition

    SciTech Connect

    Fukuda, Yukio Yamada, Daichi; Yokohira, Tomoya; Yanachi, Kosei; Yamamoto, Chiaya; Yoo, Byeonghak; Sato, Tetsuya; Yamanaka, Junji; Takamatsu, Toshiyuki; Okamoto, Hiroshi

    2016-03-15

    Radical-enhanced atomic layer deposition uses oxygen radicals generated by a remote microwave-induced plasma as an oxidant to change the surface reactions of the alternately supplied trimethylaluminum precursor and oxygen radicals on a Ge substrate, which leads to the spontaneous formation of an aluminum germanate layer. In this paper, the effects that low-energy ions, supplied from a remote microwave plasma to the substrate along with the oxygen radicals, have on the surface reactions were studied. From a comparative study of aluminum oxide deposition under controlled ion flux irradiation on the deposition surface, it was found that the ions enhance the formation of the aluminum germanate layer. The plasma potential measured at the substrate position by the Langmuir probe method was 5.4 V. Assuming that the kinetic energy of ions arriving at the substrate surface is comparable to that gained by this plasma potential, such ions have sufficient energy to induce exchange reactions of surface-adsorbed Al atoms with the underlying Ge atoms without causing significant damage to the substrate. This ion-induced exchange reaction between Al and Ge atoms is inferred to be the background kinetics of the aluminum germanate formation by radical-enhanced atomic layer deposition.

  11. Effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging

    NASA Astrophysics Data System (ADS)

    Gu, Wei; Li, Jing-yuan; Wang, Yi-de

    2015-07-01

    The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation (GND) density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 µm × 80 µm separate into fine equiaxed grains of 20 µm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83 × 1013 to 4.40 × 1011 m-2 in grains with <111> fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone (PFZ) are facilitated due to the eroding activity of the Graff etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference.

  12. Up-Regulation of a Magnesium Transporter Gene OsMGT1 Is Required for Conferring Aluminum Tolerance in Rice1[W][OA

    PubMed Central

    Chen, Zhi Chang; Yamaji, Naoki; Motoyama, Ritsuko; Nagamura, Yoshiaki; Ma, Jian Feng

    2012-01-01

    Magnesium (Mg)-mediated alleviation of aluminum (Al) toxicity has been observed in a number of plant species, but the mechanisms underlying the alleviation are still poorly understood. When a putative rice (Oryza sativa) Mg transporter gene, Oryza sativa MAGNESIUM TRANSPORTER1 (OsMGT1), was knocked out, the tolerance to Al, but not to cadmium and lanthanum, was decreased. However, this inhibition could be rescued by addition of 10 μm Mg, but not by the same concentration of barium or strontium. OsMGT1 was expressed in both the roots and shoots in the absence of Al, but the expression only in the roots was rapidly up-regulated by Al. Furthermore, the expression did not respond to low pH and other metals including cadmium and lanthanum, and was regulated by an Al-responsive transcription factor, AL RESISTANCE TRANSCRIPTION FACTOR1. An investigation of subcellular localization showed that OsMGT1 was localized to the plasma membrane. A short-term (30 min) uptake experiment with stable isotope 25Mg showed that knockout of OsMGT1 resulted in decreased Mg uptake, but that the uptake in the wild type was enhanced by Al. Mg concentration in the cell sap of the root tips was also increased in the wild-type rice, but not in the knockout lines in the presence of Al. A microarray analysis showed that transcripts of genes related to stress were more up- and down-regulated in the knockout lines. Taken together, our results indicate that OsMGT1 is a transporter for Mg uptake in the roots and that up-regulation of this gene is required for conferring Al tolerance in rice by increasing Mg concentration in the cell. PMID:22732245

  13. Nanogoethite formation from oxidation of Fe(II) sorbed on aluminum oxide: implications for contaminant reduction.

    PubMed

    Larese-Casanova, Philip; Cwiertny, David M; Scherer, Michelle M

    2010-05-15

    Ferrous iron [Fe(II)] bound to mineral surfaces has been shown to reduce several important groundwater contaminants, but little is known of the nature of the newly formed, insoluble ferric iron [Fe(III)] and whether it influences the heterogeneous contaminant reduction process. To explore how the formation and evolution of the Fe oxidation products influences contaminant reduction, we measured the kinetics of nitrobenzene reduction by Fe(II) sorbed on alpha-Al(2)O(3) while simultaneously characterizing the Fe oxidation product with Mossbauer spectroscopy and electron microscopy. After a brief period of slow kinetics, the onset of nitrobenzene reduction coincided with a change in particle suspension color from white to yellow-ocher due to formation of nanogoethite rods (alpha-FeOOH) from oxidation of sorbed Fe(II). Formation of nanogoethite on the alpha-Al(2)O(3) particles appears to promote the rapid reduction of nitrobenzene. Our results show that nanogoethite crystals can form rapidly by heterogeneous Fe(II) oxidation, and formation of goethite can profoundly influence contaminant reduction rates by Fe(II).

  14. Calcium-aluminum-rich inclusions recycled during formation of porphyritic chondrules from CH carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Krot, Alexander N.; Nagashima, Kazuhide; van Kooten, Elishevah M. M.; Bizzarro, Martin

    2017-03-01

    We report on the mineralogy, petrography, and O-isotope compositions of ∼60 Ca, Al-rich inclusions (CAIs) incompletely melted during formation of porphyritic chondrules from the CH metal-rich carbonaceous chondrites and Isheyevo (CH/CB). These include (i) relict polymineralic CAIs in porphyritic chondrules, (ii) CAIs surrounded by chondrule-like igneous rims, (iii) igneous pyroxene-rich and Type C-like CAIs, and (iv) plagioclase-rich chondrules with clusters of relict spinel grains. 26Al-26Mg systematics were measured in 10 relict CAIs and 11 CAI-bearing plagioclase-rich chondrules. Based on the mineralogy, the CH CAIs incompletely melted during chondrule formation can be divided into grossite-rich (n = 13), hibonite-rich (n = 11), spinel ± melilite-rich (n = 33; these include plagioclase-rich chondrules with clusters of relict spinel grains) types. Mineralogical observations indicate that these CAIs were mixed with different proportions of ferromagnesian silicates and experienced incomplete melting and gas-melt interaction during chondrule formation. These processes resulted in partial or complete destruction of the CAI Wark-Lovering rims, replacement of melilite by Na-bearing plagioclase, and dissolution and overgrowth of nearly end-member spinel by chromium- and iron-bearing spinel. Only two relict CAIs and two CAI-bearing chondrules show resolvable excess of radiogenic 26Mg; the inferred initial 26Al/27Al ratios are (1.7 ± 1.3) × 10-6, (3.7 ± 3.1) × 10-7, (1.9 ± 0.9) × 10-6 and (4.9 ± 2.6) × 10-6. There is a large range of Δ17O among the CH CAIs incompletely melted during chondrule formation, from ∼-37‰ to ∼-5‰; the unmelted minerals in individual CAIs, however, are isotopically uniform and systematically 16O-enriched relative to the host chondrules and chondrule-like igneous rims, which have Δ17O ranging from ∼-7‰ to ∼+4‰. Most of the CH CAIs incompletely melted during chondrule formation are mineralogically and isotopically

  15. Molecular Hydrogen Bubbles Formation on Thin Vacuum Deposited Aluminum Layers After Proton Irradiation

    NASA Astrophysics Data System (ADS)

    Sznajder, Maciej; Geppert, Ulrich

    2014-06-01

    Metals are the most common materials used in space technology. Metal structures, while used in space, are subjected to the full spectrum of the electromagnetic radiation together with particle irradiation. Hence, they undergo degradation. Future space missions are planned to proceed in the interplanetary space, where the protons of the solar wind play a very destructive role on metallic surfaces. Unfortunately, their real degradation behavior is to a great extent unknown.Our aim is to predict materials' behavior in such a destructive environment. Therefore both, theoretical and experimental studies are performed at the German Aerospace Center (DLR) in Bremen, Germany.Here, we report the theoretical results of those studies. We examine the process of H2-bubble formation on metallic surfaces. H2-bubbles are metal caps filled with Hydrogen molecular gas resulting from recombination processes of the metal free electrons and the solar protons. A thermodynamic model of the bubble growth is presented. Our model predicts e.g. the velocity of that growth and the reflectivity of foils populated by bubbles.Formation of bubbles irreversibly changes the surface quality of irradiated metals. Thin metallic films are especially sensitive for such degradation processes. They are used e.g. in the solar sail propulsion technology. The efficiency of that technology depends on the thermoptical properties of the sail materials. Therefore, bubble formation processes have to be taken into account for the planning of long-term solar sail missions.

  16. Using an ACTIVE teaching format versus a standard lecture format for increasing resident interaction and knowledge achievement during noon conference: a prospective, controlled study

    PubMed Central

    2014-01-01

    Background The traditional lecture is used by many residency programs to fulfill the mandate for regular didactic sessions, despite limited evidence to demonstrate its effectiveness. Active teaching strategies have shown promise in improving medical knowledge but have been challenging to implement within the constraints of residency training. We developed and evaluated an innovative structured format for interactive teaching within the residency noon conference. Methods We developed an ACTIVE teaching format structured around the following steps: assemble (A) into groups, convey (C) learning objectives, teach (T) background information, inquire (I) through cases and questions, verify (V) understanding, and explain (E) answer choices and educate on the learning points. We conducted a prospective, controlled study of the ACTIVE teaching format versus the standard lecture format, comparing resident satisfaction, immediate knowledge achievement and long-term knowledge retention. We qualitatively assessed participating faculty members’ perspectives on the faculty development efforts and the feasibility of teaching using the ACTIVE format. Results Sixty-nine internal medicine residents participated in the study. Overall, there was an improvement in perceived engagement using the ACTIVE teaching format (4.78 vs. 3.80, P < 0.01), with no increase in stress or decrement in break time. There was an improvement in initial knowledge achievement with the ACTIVE teaching format (overall absolute score increase of 11%, P = 0.04) and a trend toward improvement in long-term knowledge retention. Faculty members felt adequately prepared to use the ACTIVE teaching format, and enjoyed teaching with the ACTIVE teaching format more than the standard lecture. Conclusions A structured ACTIVE teaching format improved resident engagement and initial knowledge, and required minimal resources. The ACTIVE teaching format offers an exciting alternative to the standard lecture for

  17. Using an ACTIVE teaching format versus a standard lecture format for increasing resident interaction and knowledge achievement during noon conference: a prospective, controlled study.

    PubMed

    Sawatsky, Adam P; Berlacher, Kathryn; Granieri, Rosanne

    2014-07-01

    The traditional lecture is used by many residency programs to fulfill the mandate for regular didactic sessions, despite limited evidence to demonstrate its effectiveness. Active teaching strategies have shown promise in improving medical knowledge but have been challenging to implement within the constraints of residency training. We developed and evaluated an innovative structured format for interactive teaching within the residency noon conference. We developed an ACTIVE teaching format structured around the following steps: assemble (A) into groups, convey (C) learning objectives, teach (T) background information, inquire (I) through cases and questions, verify (V) understanding, and explain (E) answer choices and educate on the learning points. We conducted a prospective, controlled study of the ACTIVE teaching format versus the standard lecture format, comparing resident satisfaction, immediate knowledge achievement and long-term knowledge retention. We qualitatively assessed participating faculty members' perspectives on the faculty development efforts and the feasibility of teaching using the ACTIVE format. Sixty-nine internal medicine residents participated in the study. Overall, there was an improvement in perceived engagement using the ACTIVE teaching format (4.78 vs. 3.80, P < 0.01), with no increase in stress or decrement in break time. There was an improvement in initial knowledge achievement with the ACTIVE teaching format (overall absolute score increase of 11%, P = 0.04) and a trend toward improvement in long-term knowledge retention. Faculty members felt adequately prepared to use the ACTIVE teaching format, and enjoyed teaching with the ACTIVE teaching format more than the standard lecture. A structured ACTIVE teaching format improved resident engagement and initial knowledge, and required minimal resources. The ACTIVE teaching format offers an exciting alternative to the standard lecture for resident noon conference and is easy to implement.

  18. Fundamental study of the austenite formation and decomposition in low-silicon, aluminum added TRIP steels

    NASA Astrophysics Data System (ADS)

    Garcia-Gonzalez, Jose Enrique

    2005-11-01

    TRIP (Transformation Induced Plasticity) steels are under development for automotive applications that require high strength and excellent formability. Conventional TRIP steels consist of a multiphase microstructure comprised of a ferrite matrix with a dispersion of bainite and metastable retained austenite. The high ductility exhibited by these steels results from the transformation of the metastable retained austenite to martensite during straining. In conventional TRIP steel processing, the multiphase microstructure is obtained by controlled cooling from the alpha + gamma region to an isothermal holding temperature. During this holding, bainite forms and carbon is rejected out into the austenite, which lowers the Ms temperature and stabilizes the austenite to room temperature. In this research project, a fundamental study of a low-Si, Mo-Nb added cold rolled TRIP steel with and without Al additions was conducted. In this study, the recrystallization of cold-rolled ferrite, the formation of austenite during intercritical annealing and the characteristics of the decomposition of the intercritically annealed austenite by controlled cooling rates were systematically assessed. Of special interest were: (i) the effect of the initial hot band microstructure, (ii) the formation of epitaxial ferrite during cooling from the intercritical annealing temperature to the isothermal holding temperature, (iii) the influence of the intercritically annealed austenite on the formation of bainite during the isothermal holding temperature, and (iv) the influence of the processing variables on the type, amount, composition and stability of the retained austenite. During this research study, techniques such as OM, SEM, EBSD, TEM, XRD and Magnetometry were used to fully characterize the microstructures. Furthermore, a Gleeble 3500 unit at US Steel Laboratories was used for dilatometry studies and to simulate different CGL processing routes, from which specimens were obtained to evaluate

  19. A thermodynamic prediction for microporosity formation in aluminum-rich Al-Cu alloys

    NASA Technical Reports Server (NTRS)

    Poirier, D. R.; Yeum, K.; Maples, A. L.

    1987-01-01

    A computer model is used to predict the formation and degree of microporosity in a directionally solidified Al-4.5 wt pct Cu alloy, considering the interplay between solidification shrinkage and gas porosity. Macrosegregation theory is used to determine the local pressure within the interdendritic liquid. Results show interdendritic porosity for initial hydrogen contents in the 0.03-1 ppm range, and none below contents of 0.03. An increase in either the thermal gradient or the solidification rate is show to decrease the amount of interdendritic porosity.

  20. Interface Formation During Fusion™ Casting of AA3003/AA4045 Aluminum Alloy Ingots

    NASA Astrophysics Data System (ADS)

    Di Ciano, Massimo; Caron, E. J. F. R.; Weckman, D. C.; Wells, M. A.

    2015-12-01

    Fusion™ casting is a unique Direct Chill continuous casting process whereby two different alloys can be cast simultaneously, producing a laminated ingot for rolling into clad sheet metal such as AA3003/AA4045 brazing sheet. Better understanding of the wetting and interface formation process during Fusion™ casting is required to further improve process yields and also explore use of other alloy systems for new applications. In this research, AA3003-core/AA4045-clad ingots were cast using a well-instrumented lab-scale Fusion™ casting system. As-cast Fusion™ interfaces were examined metallurgically and by mechanical testing. Computational fluid dynamic analyses of the FusionTM casts were also performed. It was shown that the liquid AA4045-clad alloy was able to successfully wet and create an oxide-free, metallurgical, and mechanically sound interface with the lightly oxidized AA3003-core shell material. Based on the results of this study, it is proposed that the bond formation process at the alloys interface during casting is a result of discrete penetration of AA4045 liquid at defects in the preexisting AA3003 oxide, dissolution of underlying AA3003 by liquid AA4045, and subsequent bridging between penetration sites. Spot exudation on the AA3003 chill cast surface due to remelting and inverse segregation may also improve the wetting and bonding process.

  1. Ultrafast electronic and vibrational dynamics in brominated aluminum corroles: Energy relaxation and triplet formation

    PubMed Central

    Stensitzki, T.; Yang, Y.; Berg, A.; Mahammed, A.; Gross, Z.; Heyne, K.

    2016-01-01

    We combined femtosecond (fs) VIS pump–IR probe spectroscopy with fs VIS pump–supercontinuum probe spectroscopy to characterize the photoreaction of the hexacoordinated Al(tpfc-Br8)(py)2 in a comprehensive way. Upon fs excitation at ∼400 nm in the Soret band, the excitation energy relaxes with a time constant of (250 ± 80) fs to the S2 and S1 electronic excited states. This is evident from the rise time of the stimulated emission signal in the visible spectral range. On the same time scale, narrowing of broad infrared signals in the C=C stretching region around 1500 cm−1 is observed. Energy redistribution processes are visible in the vibrational and electronic dynamics with time constants between ∼2 ps and ∼20 ps. Triplet formation is detected with a time constant of (95 ± 3) ps. This is tracked by the complete loss of stimulated emission. Electronic transition of the emerging triplet absorption band overlaps considerably with the singlet excited state absorption. In contrast, two well separated vibrational marker bands for triplet formation were identified at 1477 cm−1 and at 1508 cm−1. These marker bands allow a precise identification of triplet dynamics in corrole systems. PMID:27226980

  2. Planetary systems: Formation, evolution, and detection; Proceedings of the First International Conference, Pasadena, California, Dec. 8-10, 1992

    NASA Technical Reports Server (NTRS)

    Burke, Bernard F. (Editor); Rahe, Jurgen H. (Editor); Roettger, Elizabeth E. (Editor)

    1994-01-01

    The papers in these proceedings relate to our present understanding about planetary system formation, the various methods and imaging techniques that may be used in searching for planets (or protoplanets) that are outside of the solar system (extrasolar planets), and the stars that seem most likely to have planetary systems, using recent observations. It was noted at the conference that, at this time, the only confirmed example of a planetary system is the one that surrounds our sun.

  3. Planetary systems: Formation, evolution, and detection; Proceedings of the First International Conference, Pasadena, California, Dec. 8-10, 1992

    NASA Technical Reports Server (NTRS)

    Burke, Bernard F. (Editor); Rahe, Jurgen H. (Editor); Roettger, Elizabeth E. (Editor)

    1994-01-01

    The papers in these proceedings relate to our present understanding about planetary system formation, the various methods and imaging techniques that may be used in searching for planets (or protoplanets) that are outside of the solar system (extrasolar planets), and the stars that seem most likely to have planetary systems, using recent observations. It was noted at the conference that, at this time, the only confirmed example of a planetary system is the one that surrounds our sun.

  4. Silicon nitride-aluminum oxide solid solution (SiAION) formation and densification by pressure sintering

    NASA Technical Reports Server (NTRS)

    Yeh, H. C.; Sanders, W. A.; Fiyalko, J. L.

    1975-01-01

    Stirred-ball-mill-blended Si3N4 and Al2O3 powders were pressure sintered in order to investigate the mechanism of solid solution formation and densification in the Si3N4-Al2O3 system. Powder blends with Si3N4:Al2O3 mole ratios of 4:1, 3:2, and 2:3 were pressure sintered at 27.6-MN/sq m pressure at temperatures to 17000 C (3090 F). The compaction behavior of the powder blends during pressure sintering was determined by observing the density of the powder compact as a function of temperature and time starting from room temperature. This information, combined with the results of X-ray diffraction and metallographic analyses regarding solutioning and phase transformation phenomena in the Si3N4-Al2O3 system, was used to describe the densification behavior.

  5. Catalysts on the basis of activated aluminum alloys: III. Formation of oxide alumina catalysts

    SciTech Connect

    Yakerson, V.I.; Dykh, Zh.L.; Subbotin, A.N.

    1995-11-01

    The formation of the bulk and surface of a new generation of oxide alumina catalysts is studied by XRD, thermal analysis, adsorption, and IR spectroscopy. The oxide alumina catalysts exhibit a developed surface area (up to 320 m{sup 2}/g) and diverse porous structures. Three types of non-associated OH groups, characterized by the different number of adjacent Al atoms, as well as OH groups with a strong hydrogen bond are found at the surface. Lewis, but not Br6ensted, acidic properties (revealed by pyridine adsorption) are inherent to the catalyst surface. The number of Lewis acid sites increases from 1.0 to 2.2 {mu}mol/m{sup 2} with an increasing concentration of activating agents from 2 to 20 wt %.

  6. Spontaneous formation of complex structures made from elastic membranes in an aluminum-hydroxide-carbonate system

    NASA Astrophysics Data System (ADS)

    Kiehl, Micah; Kaminker, Vitaliy; Pantaleone, James; Nowak, Piotr; Dyonizy, Agnieszka; Maselko, Jerzy

    2015-06-01

    A popular playground for studying chemo-hydrodynamic patterns and instabilities is chemical gardens, also known as silicate gardens. In these systems, complex structures spontaneously form, driven by buoyant forces and either osmotic or mechanical pumps. Here, we report on systems that differ somewhat from classical chemical gardens in that the membranes are much more deformable and soluble. These properties lead to structures that self-construct and evolve in new ways. For example, they exhibit the formation of chemical balloons, a new growth mechanism for tubes, and also the homologous shrinking of these tubes. The stretching mechanism for the membranes is probably different than for other systems by involving membrane "self-healing." Other unusual properties are osmosis that sometimes occurs out of the structure and also small plumes that flow away from the structure, sometimes upwards, and sometimes downwards. Mathematical models are given that explain some of the observed phenomena.

  7. Microstructure investigations of streak formation in 6063 aluminum extrusions by optical metallographic techniques.

    PubMed

    Vander Voort, George; Suárez-Peña, Beatriz; Asensio-Lozano, Juan

    2013-04-01

    The present study investigates the effect of the solidification strategy for AA 6063 alloy on the surface appearance of anodized extrusions. The microstructure of the samples was analyzed using both light optical microscopy and scanning electron microscopy. Results show that if heavy segregation occurs from rapid solidification, coarse Mg2Si particles form, thus reducing the potential for precipitation strengthening by the finer β-Mg2Si developed in the solid state. Differentially-strained regions formed during hot extrusion induce differences in particle size for magnesium silicide (Mg2Si) precipitates. Anodizing generates surface roughness due to Mg2Si particle dissolution and AlFeSi decohesion, which is related to both particle size and deformation. During anodizing, an oxide layer forms on the surface of the extruded products, which can lead to streak formation, usually a subject of rejection due to unacceptable heterogeneous reflectivity.

  8. Keto-Mycolic Acid-Dependent Pellicle Formation Confers Tolerance to Drug-Sensitive Mycobacterium tuberculosis

    PubMed Central

    Sambandan, Dhinakaran; Dao, Dee N.; Weinrick, Brian C.; Vilchèze, Catherine; Gurcha, Sudagar S.; Ojha, Anil; Kremer, Laurent; Besra, Gurdyal S.; Hatfull, Graham F.; Jacobs, William R.

    2013-01-01

    ABSTRACT The chronic nature of tuberculosis (TB), its requirement of long duration of treatment, its ability to evade immune intervention, and its propensity to relapse after drug treatment is discontinued are reminiscent of other chronic, biofilm-associated bacterial diseases. Historically, Mycobacterium tuberculosis was grown as a pellicle, a biofilm-like structure, at the liquid-air interface in a variety of synthetic media. Notably, the most widely administered human vaccine, BCG, is grown as a pellicle for vaccine production. However, the molecular requirements for this growth remain ill defined. Here, we demonstrate that keto-mycolic acids (keto-MA) are essential for pellicle growth, and mutants lacking in or depleted of this MA species are unable to form a pellicle. We investigated the role of the pellicle biofilm in the reduction of antibiotic sensitivity known as drug tolerance using the pellicle-defective ΔmmaA4 mutant strain. We discovered that the ΔmmaA4 mutant, which is both pellicle defective and highly sensitive to rifampicin (RIF) under planktonic growth, when incorporated within the wild-type pellicle biofilm, was protected from the bactericidal activity of RIF. The observation that growth within the M. tuberculosis pellicle biofilm can confer drug tolerance to a drug-hypersensitive strain suggests that identifying molecular requirements for pellicle growth could lead to development of novel interventions against mycobacterial infections. Our findings also suggest that a class of drugs that can disrupt M. tuberculosis biofilm formation, when used in conjunction with conventional antibiotics, has the potential to overcome drug tolerance. PMID:23653446

  9. Characterizing Pyroxene Reaction Space in Calcium-Aluminum Rich Inclusions: Oxidation During CAI Rim Formation

    NASA Astrophysics Data System (ADS)

    Dyl, K. A.; Young, E. D.

    2009-12-01

    We define the reaction space that controls changes in pyroxene composition in CAIs and Wark-Lovering (WL) rims in an oxidizing solar nebula. Ti-rich pyroxenes in CAIs record a sub-solar oxygen fugacity (Ti3+/Ti4+~1.5). WL rim pyroxenes in the CAI Leoville 144A have a distinctly lower oxidation state.This difference supports WL rim condensation in an environment of increasing O2(g) and Mg(g) (Simon et al. 2005). We used the following phase components to identify four linearly independent reactions (Thompson 1982): diopside, CaTs (Al2Mg-1Si-1), T3 (Ti3+AlMg-1Si-1), T4 (Ti4+Al2Mg-1Si-2), En (MgCa-1), perovskite, O(g), Mg(g), SiO(g), and Ca(g). Compositional variation in this system is dominated by two reactions. The first is oxidation of Ti3+ via reaction with O and Mg in the gas phase: 1.5 O(g) + Mg(g) → ¼ Di + [Ti4+Mg3/4Ti3+-1Ca-1/4Si-1/2] (1). Pyroxene is produced and En is introduced. The second reaction (2) is perovskite formation. It is observed in the WL rim of Leoville 144A, and experiments confirm that an elevated Ti component converts pyroxene to perovskite(Gupta et al. 1973). MgCa-1 is the third linearly independent reaction (3). They combine to give: ½ Di + x Ca(g)→ x Mg(g)+ Pv + [Mg1/2-xSiTi4+-1Ca-1/2+x](2,3). Unlike (1), pyroxene is consumed in this reaction. The parameter x defines the extent of Mg-Ca exchange. When x > 0.5, WL rim formation occurs in an environment where Mg is volatile and Ca condenses. The reaction space defined by reactions (1) and (2,3) describes the transition from CAI interior to WL rims. WL rim pyroxene Ti contents, [CaTs], and Ca < 1 pfu are all explained in this space. The fourth linearly independent reaction is SiO(g):1/8 Di + ¼ Mg(g)→ ¾ SiO(g) + [Mg3/8Ca1/8Ti4+Ti3+-1Si-1/2](4). Silica reduction forms Ti4+, releasing SiO(g). (4) does not describe the oxidation of Ti3+ in WL rim pyroxene, but (1) - (4) results in En formation directly from the gas phase. This may explain WL rim analyses that have Si contents in excess

  10. The formation and structure of the oxide and hydroxide chemisorbed phases at the aluminum surface, and relevance to hydrogen embrittlement

    NASA Astrophysics Data System (ADS)

    Francis, Michael; Kelly, Robert; Neurock, Matthew

    2010-03-01

    Aluminum alloys used in aerospace structures are susceptible to environmentally assisted cracking (EAC) induced by hydrogen embrittlement (HE) (Gangloff and Ives 1990). Crack growth experiments have demonstrated a linear relation between the relative humidity of the environment and crack growth rates, indicating the importance of water (Speidel and Hyatt 1972). While the presence of water has been demonstrated to be necessary for EAC of aluminum, crack growth rates have been linked to the diffusivity of hydrogen in aluminum (Gangloff 2003) and hydrogen densities at the crack tip as high as Al2H have been observed (Young and Scully 1998). While the mechanism by which hydrogen embrittles aluminum is yet not well understood, without the entry of hydrogen into the aluminum matrix, embrittlement would not occur. While at the crack tip high hydrogen concentrations exist, the solubility of hydrogen in aluminum is normal near 1 ppm (Wolverton 2004). In this work combined first principles and kinetic Monte Carlo methods will be used to examine the oxide and hydroxide structure resulting from exposure of aluminum to H2O or O2 and relevance to hydrogen entry as well as EAC is discussed.

  11. Effect of Fe- and Si-Enriched Secondary Precipitates and Surface Roughness on Pore Formation on Aluminum Plate Surfaces During Anodizing

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanzhi; Wang, Shizhi; Yang, Qingda; Zhou, Feng

    2014-09-01

    Two twin roll casts (TRCs) and one hot rolled (HR) AA 1235 aluminum alloy plates with different microstructures are prepared. The plates were electrolyzed in a 1.2 wt% HCl solution with a voltage of 21 V and a current of 1.9 mA. The shape, size, and number of pores formed on the surfaces of these plates were analyzed and correlated with the microstructures of the plates. It is found that pores are easier to form on the alloy plates containing subgrains with a lower dislocation density inside the subgrains, rather than along the grain boundaries. Furthermore, Fe- and Si-enriched particles in the AA1235 aluminum alloys lead to the formation of pores on the surface during electrolyzing; the average precipitate sizes of 4, 3.5, and 2 μm in Alloy 1#, Alloy 2# and Alloy 3# result in the average pore sizes of 3.78, 2.76, and 1.9 μm on the surfaces of the three alloys, respectively; The G.P zone in the alloy also facilitates the surface pore formation. High-surface roughness enhances the possibility of entrapping more lubricants into the plate surface, which eventually blocks the formation of the pores on the surface of the aluminum plates in the following electrolyzing process.

  12. Aluminum colloid formation and its effect on co-precipitation of zinc during acid rock drainage remediation with clinoptilolite in a slurry bubble column

    NASA Astrophysics Data System (ADS)

    Xu, W.; Li, L. Y.; Grace, J. R.

    2012-04-01

    Zinc and other metal ions were adsorbed in a laboratory slurry bubble column (SBC) by natural clinoptilolite sorbent particles. During the remediation process, significant white precipitates were sometimes observed. Both zinc and aluminum were detected in the colloidal mixtures. It is shown that Al leached from clinoptilolite during the agitation, contributing to the precipitate. As a result of the Al leaching and increase of pH during the remediation process, the formation of an Al colloid and zinc adsorption onto it could significantly improve ARD remediation, given the high adsorption capacity of the colloid. Sorption of cations increased with increasing colloid formation. Various conditions were tested to investigate their impact on (a) dealumination of clinoptilolite; (b) Al hydrolysis/colloid formation; and (c) adsorption onto the colloidal mixture. The test results indicate that dealumination contributes to the excess aluminum in the aqueous phase and to precipitates. The excess dealumination varies with pH and agitation time. Al hydrolysis occurs with increasing pH due to the neutralization effect of clinoptilolite. A significant proportion of zinc adsorbed onto the collectible aluminum precipitates.

  13. Dynamics of plasma expansion and shockwave formation in femtosecond laser-ablated aluminum plumes in argon gas at atmospheric pressures

    SciTech Connect

    Miloshevsky, Alexander; Harilal, Sivanandan S.; Miloshevsky, Gennady Hassanein, Ahmed

    2014-04-15

    Plasma expansion with shockwave formation during laser ablation of materials in a background gasses is a complex process. The spatial and temporal evolution of pressure, temperature, density, and velocity fields is needed for its complete understanding. We have studied the expansion of femtosecond (fs) laser-ablated aluminum (Al) plumes in Argon (Ar) gas at 0.5 and 1 atmosphere (atm). The expansion of the plume is investigated experimentally using shadowgraphy and fast-gated imaging. The computational fluid dynamics (CFD) modeling is also carried out. The position of the shock front measured by shadowgraphy and fast-gated imaging is then compared to that obtained from the CFD modeling. The results from the three methods are found to be in good agreement, especially during the initial stage of plasma expansion. The computed time- and space-resolved fields of gas-dynamic parameters have provided valuable insights into the dynamics of plasma expansion and shockwave formation in fs-pulse ablated Al plumes in Ar gas at 0.5 and 1 atm. These results are compared to our previous data on nanosecond (ns) laser ablation of Al [S. S. Harilal et al., Phys. Plasmas 19, 083504 (2012)]. It is observed that both fs and ns plumes acquire a nearly spherical shape at the end of expansion in Ar gas at 1 atm. However, due to significantly lower pulse energy of the fs laser (5 mJ) compared to pulse energy of the ns laser (100 mJ) used in our studies, the values of pressure, temperature, mass density, and velocity are found to be smaller in the fs laser plume, and their time evolution occurs much faster on the same time scale. The oscillatory shock waves clearly visible in the ns plume are not observed in the internal region of the fs plume. These experimental and computational results provide a quantitative understanding of plasma expansion and shockwave formation in fs-pulse and ns-pulse laser ablated Al plumes in an ambient gas at atmospheric pressures.

  14. Allotropic control: How certain fluorinated carbonate electrolytes protect aluminum current collectors by promoting the formation of insoluble coordination polymers

    DOE PAGES

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Abraham, Daniel P.

    2016-07-28

    Here, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, lightweight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X = TFSI), and lithium bis(fluorosulfonyl)imide (X = FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V versus Li/Li+. For LiBF4 and LiPF6, themore » release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V versus Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.« less

  15. Allotropic control: How certain fluorinated carbonate electrolytes protect aluminum current collectors by promoting the formation of insoluble coordination polymers

    SciTech Connect

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Abraham, Daniel P.

    2016-07-28

    Here, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, lightweight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X = TFSI), and lithium bis(fluorosulfonyl)imide (X = FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V versus Li/Li+. For LiBF4 and LiPF6, the release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V versus Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.

  16. Allotropic control: How certain fluorinated carbonate electrolytes protect aluminum current collectors by promoting the formation of insoluble coordination polymers

    SciTech Connect

    Shkrob, Ilya A.; Pupek, Krzysztof Z.; Abraham, Daniel P.

    2016-07-28

    Here, there is a strong incentive for increasing the operation voltage of Li-ion cells above 4.5 V in order to increase the density of stored energy. Aluminum is an inexpensive, lightweight metal that is commonly used as a positive electrode current collector in these cells. Imide LiX salts, such as lithium bis(trifluoromethylsulfonyl)imide (X = TFSI), and lithium bis(fluorosulfonyl)imide (X = FSI), are chemically stable on the energized lithiated transition metal oxide electrodes, but their presence in the electrolyte causes rapid anodic dissolution and pitting of Al current collectors at potentials exceeding 4.0 V versus Li/Li+. For LiBF4 and LiPF6, the release of HF near the energized surfaces passivates the exposed Al metal, inhibiting this pitting corrosion, but it also causes the gradual degradation of the cathode active material, negating this important advantage. Here we report that in certain electrolytes containing fluorinated carbonate solvents and LiX salts, the threshold voltage for safe operation of Al current collectors can be increased to 5.5 V versus Li/Li+. Interestingly, the most efficient solvent also facilitates the formation of an insoluble gel when AlX3 is introduced into this solvent. We suggest that this solvent promotes the aggregation of coordination polymers of AlX3 at the exposed Al surface that isolate this surface from the electrolyte, thereby preventing further Al dissolution and corrosion. Other examples of Al collector protection may also involve this mechanism. Our study suggests that such “allotropic control” could be a way of widening the operation window of Li-ion cells without electrode deterioration, Al current collector corrosion, and electrolyte breakdown.

  17. Effects of filling material and laser power on the formation of intermetallic compounds during laser-assisted friction stir butt welding of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Fei, Xinjiang; Jin, Xiangzhong; Peng, Nanxiang; Ye, Ying; Wu, Sigen; Dai, Houfu

    2016-11-01

    In this paper, two kinds of materials, Ni and Zn, are selected as filling material during laser-assisted friction stir butt welding of Q235 steel and 6061-T6 aluminum alloy, and their influences on the formation of intermetallic compounds on the steel/aluminum interface of the joints were first studied. SEM was used to analyze the profile of the intermetallic compound layer and the fractography of tensile fracture surfaces. In addition, EDS was applied to investigate the types of the intermetallic compounds. The results indicate that a thin iron-abundant intermetallic compound layer forms and ductile fracture mode occurs when Ni is added, but a thick aluminum-abundant intermetallic compound layer generates and brittle fracture mode occurs when Zn is added. So the tensile strength of the welds with Ni as filling material is greater than that with Zn as filling material. Besides, the effect of laser power on the formation of intermetallic compound layer when Ni is added was investigated. The preheated temperature field produced by laser beam in the cross section of workpiece was calculated, and the tensile strength of the joints at different laser powers was tested. Results show that only when suitable laser power is adopted, can suitable preheating temperature of the steel reach, then can thin intermetallic compound layer form and high tensile strength of the joints reach. Either excessive or insufficient laser power will reduce the tensile strength of the joints.

  18. The Formation, Development and Contribution of the New Ideals in Education Conferences, 1914-1937

    ERIC Educational Resources Information Center

    Howlett, John

    2017-01-01

    This paper seeks to explore the development, impact and contribution made by the New Ideals in Education conferences, which were held between 1914 and 1937. In particular, it will examine how the group emerged from the English Montessori Society and forged an identity of its own based on the thoughts and ideas of its two major protagonists: Edmond…

  19. a Study of the Nature of the Schottky Barrier during Ultralow Coverage Stages of GALLIUM-ARSENIDE(110)/ALUMINUM and GALLIUM-ARSENIDE(110)/INDIUM Interface Formation.

    NASA Astrophysics Data System (ADS)

    Daniels, Robert Richard

    We present a study of the GaAs(110)/Al and GaAs(110)/In interface formation from submonolayer to bulk metallic coverages using synchrotron radiation photoemission spectroscopy. The experiments monitored changes in the surface and bulk core level binding energies and valence electronic state densities resulting from the deposition of aluminum or indium. These spectroscopic changes indicate the occurrence of specific chemical processes during the formation of the interface. This represents the first study of ultralow metal coverages (< 1/20 monolayer) on a semiconductor using this approach. Our results emphasize the critical importance of characterizing this regime in order to understand the metal-semiconductor interface. Extreme differences in the electronic properties are observed between these two interfaces and can be understood in terms of the different chemical processes. In particular, our results indicate the predominance of the aluminum or indium adatom-adatom bonding (cluster formation) over the metal-semiconductor bonding at the interface; we demonstrate that this is the key factor in determining such properties as the Schottky barrier height and coverage stabilization of the barrier. The relevance of current models of metal -semiconductor interfaces to GaAs(110)/Al and GaAs(110)/In is discussed in terms of metallic cluster formation. In particular, the influence of semiconductor surface defect states and metal induced gap states is examined.

  20. Aluminum potentiates glutamate-induced calcium accumulation and iron-induced oxygen free radical formation in primary neuronal cultures.

    PubMed

    Mundy, W R; Freudenrich, T M; Kodavanti, P R

    1997-01-01

    Aluminum is a neurotoxic metal that may be involved in the progression of neurodegenerative diseases, including Alzheimer disease and amyotrophic lateral sclerosis (ALS). Although the mechanism of action is not known, aluminum has been shown to alter Ca2+ flux and homeostasis, and facilitate peroxidation of membrane lipids. Since abnormal increases of intracellular Ca2+ and oxygen free radicals have both been implicated in pathways leading to neurodegeneration, we examined the effect of aluminum on these parameters in vitro using primary cultures of cerebellar granule cells. Exposure to glutamate (1-300 microM) caused a concentration-dependent uptake of 45Ca in granule cells to a maximum of 280% of basal. Pretreatment with AlCl3 (1-1000 microM) had no effect on 45Ca accumulation, but increased the uptake induced by glutamate. Similarly, AlCl3 had no effect on intracellular free Ca2+ levels measured using fluorescent probe fura-2, but potentiated the increase induced by glutamate. The production of reactive oxygen species (ROS) was examined using the fluorescent probe dichlorofluorescin. By itself, AlCl3 had little effect on ROS production. However, AlCl3 pretreatment potentiated the ROS production induced by 50 microM Fe2+. These results suggest that aluminum may facilitate increases in intracellular Ca2+ and ROS, and potentially contribute to neurotoxicity induced by other neurotoxicants.

  1. Influence of Gas Composition and Exposure Cycle on the Formation of Surface and Subsurface Oxides in Iron-Aluminum-Based Alloys at High Temperatures

    NASA Astrophysics Data System (ADS)

    Bott, June H.; Yin, Hogbin; Sridhar, Seetharaman; Auinger, Michael

    2016-08-01

    The slab reheating process of binary iron-aluminum alloys and an industrial TRIP steel grade has been investigated in both dry and wet atmospheres. The presence of water vapor has a significant effect on the overall scale growth and internal corrosion depth. Heating rate greatly influences the porosity of the surface oxide layer with the surface getting more porous at faster heating rates. Nitride formation could be suppressed in the presence of water vapor, leading to a reduction of internal corrosion depth and a better formability of the final material. Experimental results were compared to thermodynamic predictions and critically discussed.

  2. Aluminum Hydroxide

    MedlinePlus

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  3. Conference Resolution

    NASA Astrophysics Data System (ADS)

    2009-04-01

    Since the first IUPAP International Conference on Women in Physics (Paris, March 2002) and the Second Conference (Rio de Janeiro, May 2005), progress has continued in most countries and world regions to attract girls to physics and advance women into leadership roles, and many working groups have formed. The Third Conference (Seoul, October 2008), with 283 attendees from 57 countries, was dedicated to celebrating the physics achievements of women throughout the world, networking toward new international collaborations, building each participant's capacity for career success, and aiding the formation of active regional working groups to advance women in physics. Despite the progress, women remain a small minority of the physics community in most countries.

  4. Chemical interactions in the aluminum-carbon and aluminum-silicon carbide systems

    NASA Technical Reports Server (NTRS)

    Maruyama, Benji; Ohuchi, Fumio S.; Rabenberg, L.

    1990-01-01

    XPS was used to investigate the influence of O2 and H2O on the formation of aluminum carbide at Al-C and Al-SiC interfaces. It was determined that dosing the interfaces with H2O catalyzed the formation of aluminum carbide in both systems. This result is consistent with the oxidation model of carbide formation (developed to understand the kinetics of aluminum carbide formation at graphite-aluminum interfaces). These results imply that the formation of aluminum carbide in graphite- and SiC-reinforced metal-matrix composites, which severely degrades the composite mechanical properties by degrading the fiber and interface strength is catalyzed.

  5. Study on the Formation and Characterization of the Intermetallics in Friction Stir Welding of Aluminum Alloy to Coated Steel Sheet Lap Joint

    NASA Astrophysics Data System (ADS)

    Das, H.; Ghosh, R. N.; Pal, T. K.

    2014-10-01

    Multimaterial fabrication such as joining of steel and aluminum is currently prominent in a variety of industries. Friction stir welding is a novel solid-state welding process that causes good joint strength between steel and aluminum. However, the phenomenon contributing significant strength at the interface is not yet clear. In the present study, the interface of the friction stir lap-welded aluminum and coated steel sheet having joint strength maximum (71.4 pct of steel base metal) and minimum, respectively, under two parameter combinations, i.e., 1000 rpm 50 mm min-1 and 500 rpm 100 mm min-1, was exclusively characterized by X-ray diffraction, transmission electron microscopy (TEM), concentration profile, and elemental mapping by electron-probe microanalysis. A TEM-assisted EDS study identifies the morphologies of large size Al13Fe4 and small size Fe3Al-type intermetallic compounds at the interface. The diffusion-induced intermetallic growth (thickness) measured from a backscattered image and concentration profile agreed well with the numerically calculated one. The growth of these two phases at 1000 rpm 50 mm min-1 is attributed to the slower cooling rate (~3.5 K/s) with higher diffusion time (44 seconds) along the interface in comparison to the same for 500 rpm 100 mm min-1 with faster cooling rate (~10 K/s) and less diffusion time (13.6 seconds). The formation of thermodynamically stable and hard intermetallic phase Al13Fe4 at 1000 rpm and travel speed 50 mm min-1 in amounts higher than 500 rpm and a travel speed of 100 mm min-1 results in better joint strength, i.e., 71.4 pct, of the steel base metal.

  6. The detection of tightly closed flaws by nondestructive testing (NDT) methods. [fatigue crack formation in aluminum alloy test specimens

    NASA Technical Reports Server (NTRS)

    Rummel, W. D.; Rathke, R. A.; Todd, P. H., Jr.; Mullen, S. J.

    1975-01-01

    Liquid penetrant, ultrasonic, eddy current and X-radiographic techniques were optimized and applied to the evaluation of 2219-T87 aluminum alloy test specimens in integrally stiffened panel, and weld panel configurations. Fatigue cracks in integrally stiffened panels, lack-of-fusion in weld panels, and fatigue cracks in weld panels were the flaw types used for evaluation. A 2319 aluminum alloy weld filler rod was used for all welding to produce the test specimens. Forty seven integrally stiffened panels containing a total of 146 fatigue cracks, ninety three lack-of-penetration (LOP) specimens containing a total of 239 LOP flaws, and one-hundred seventeen welded specimens containing a total of 293 fatigue cracks were evaluated. Nondestructive test detection reliability enhancement was evaluated during separate inspection sequences in the specimens in the 'as-machined or as-welded', post etched and post proof loaded conditions. Results of the nondestructive test evaluations were compared to the actual flaw size obtained by measurement of the fracture specimens after completing all inspection sequences. Inspection data were then analyzed to provide a statistical basis for determining the flaw detection reliability.

  7. Formation of the structure of thin-sheet rolled product from a high-strength sparingly alloyed aluminum alloy ``nikalin''

    NASA Astrophysics Data System (ADS)

    Shurkin, P. K.; Belov, N. A.; Akopyan, T. K.; Alabin, A. N.; Aleshchenko, A. S.; Avxentieva, N. N.

    2017-09-01

    The regime of thermomechanical treatment of flat ingots of a high-strength sparingly alloyed alloy based on the Al-Zn-Mg-Ni-Fe system upon the production of thin-sheet rolled products with a reduction of more than 97% has been substantiated. Using experimental and calculated methods, the structure and phase composition of the experimental alloy in the as cast and deformed state and after heat treatment including quenching with subsequent aging have been studied. It has been found that the structure of the wrought semi-finished products after aging according to T and T1 regimes consists of the precipitation-hardened aluminum matrix and uniformly distributed isolated particles of Al9FeNi with a size of 1-2 μm, which provides a combination of high strength and satisfactory plasticity at the level of standard high-strength aluminum alloys of the Al-Zn-Mg-Cu system. The fractographic analysis confirmed that the tested samples underwent a ductile fracture.

  8. Richtmyer-Meshkov jet formation from rear target ripples in plastic and plastic/aluminum laser targets

    NASA Astrophysics Data System (ADS)

    Aglitskiy, Y.; Velikovich, A. L.; Karasik, M.; Serlin, V.; Weaver, J. L.; Schmitt, A. J.; Obenschain, S. P.

    2015-11-01

    We report experimental observations of jets produced from the rear surface of laser targets after a passage of the laser-driven shock wave. As in our previous work, Aglitskiy et al., Phys. Plasmas (2012), the jets are produced via the shaped-charge mechanism, a manifestation of a Richtmyer-Meshkov instability for a particular case of the Atwood number A =-1. The experiments done on the KrF Nike laser facility with laser wavelength 248 nm, a 4 ns pulse, and low-energy drive regime that used only 1 to 3 overlapping Nike beams and generated ablative pressure below 1 Mbar. Our 50 um thick planar targets were rippled on the rear side with wavelength 45 μm and peak-to-valley amplitude 15 μm. The targets were made either of solid plastic or of aluminum with a 10 μm thick plastic ablator attached to avoid the radiation preheat. The jets were extremely well collimated, which made possible our side-on observations with monochromatic x-ray imaging. We saw a regular set of jets, clearly separated along the 500 μm line of sight. Aluminum jets were found to be slightly better collimated than plastic jets. A quasi-spherical late-time expansion of Al jets starting from the tips has not been previously seen in experiments or simulations. Work supported by the US DOE/NNSA.

  9. MicroRNA filters Hox temporal transcription noise to confer boundary formation in the spinal cord

    NASA Astrophysics Data System (ADS)

    Li, Chung-Jung; Hong, Tian; Tung, Ying-Tsen; Yen, Ya-Ping; Hsu, Ho-Chiang; Lu, Ya-Lin; Chang, Mien; Nie, Qing; Chen, Jun-An

    2017-03-01

    The initial rostrocaudal patterning of the neural tube leads to differential expression of Hox genes that contribute to the specification of motor neuron (MN) subtype identity. Although several 3' Hox mRNAs are expressed in progenitors in a noisy manner, these Hox proteins are not expressed in the progenitors and only become detectable in postmitotic MNs. MicroRNA biogenesis impairment leads to precocious expression and propagates the noise of Hoxa5 at the protein level, resulting in an imprecise Hoxa5-Hoxc8 boundary. Here we uncover, using in silico simulation, two feed-forward Hox-miRNA loops accounting for the precocious and noisy Hoxa5 expression, as well as an ill-defined boundary phenotype in Dicer mutants. Finally, we identify mir-27 as a major regulator coordinating the temporal delay and spatial boundary of Hox protein expression. Our results provide a novel trans Hox-miRNA circuit filtering transcription noise and controlling the timing of protein expression to confer robust individual MN identity.

  10. Rigorous simulation of OCT image formation using Maxwell's equations in three dimensions (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Munro, Peter R. T.; Curatolo, Andrea; Sampson, David D.

    2016-03-01

    Existing models of image formation in optical coherence tomography are based upon the extended Huygens-Fresnel formalism. These models all, to varying degrees, rely on scatterer ensemble averages, rather than deterministic scattering distributions. Whilst the former is sometimes preferable, there are a growing number of applications where the ability to predict image formation based upon deterministic refractive index distributions is of great interest, including, for example, image formation in turbid tissue. A rigorous model based upon three-dimensional solutions of Maxwell's equations offers a number of tantalising opportunities. For example, shedding light on features near or below the resolution of an OCT system and on the impact of phenomena usually described as diffraction, interference and scattering, but which more generally result from light scattering satisfying Maxwell's equations. A rigorous model allows inverse scattering methods to be developed not requiring the first-order Born approximation. Finally, a rigorous model can provide gold standard verification of myriad quantitative techniques currently being developed throughout the field. We have developed the first such model of image formation based upon three-dimensional solutions of Maxwell's equations, which has vastly different properties to models based on two-dimensional solutions. Although we present simulated B-scans, this model is equally applicable to C-scans. This has been made possible by advances in computational techniques and in computational resources routinely available. We will present the main features of our model, comparisons of measured and simulated image formation for phantoms and discuss the future of rigorous modelling in optical coherence tomography research and application.

  11. Teacher Perceptions about Observation Conferences: What Do Teachers Think about Their Formative Supervision in One US School District?

    ERIC Educational Resources Information Center

    Range, Bret G.; Young, Suzie; Hvidston, David

    2013-01-01

    This study measured teachers' perceptions about the important elements of the pre- and post-observation conferences within one school district in a US state. Overall, respondents valued the post-observation conference more than the pre-observation conference and identified trusting relationships, constructive feedback, reflection and areas of…

  12. Teacher Perceptions about Observation Conferences: What Do Teachers Think about Their Formative Supervision in One US School District?

    ERIC Educational Resources Information Center

    Range, Bret G.; Young, Suzie; Hvidston, David

    2013-01-01

    This study measured teachers' perceptions about the important elements of the pre- and post-observation conferences within one school district in a US state. Overall, respondents valued the post-observation conference more than the pre-observation conference and identified trusting relationships, constructive feedback, reflection and areas of…

  13. Modeling and interpreting speckle pattern formation in swept-source optical coherence tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Demidov, Valentin; Vitkin, I. Alex; Doronin, Alexander; Meglinski, Igor

    2017-03-01

    We report on the development of a unified Monte-Carlo based computational model for exploring speckle pattern formation in swept-source optical coherence tomography (OCT). OCT is a well-established optical imaging modality capable of acquiring cross-sectional images of turbid media, including biological tissues, utilizing back scattered low coherence light. The obtained OCT images include characteristic features known as speckles. Currently, there is a growing interest to the OCT speckle patterns due to their potential application for quantitative analysis of medium's optical properties. Here we consider the mechanisms of OCT speckle patterns formation for swept-source OCT approaches and introduce further developments of a Monte-Carlo based model for simulation of OCT signals and images. The model takes into account polarization and coherent properties of light, mutual interference of back-scattering waves, and their interference with the reference waves. We present a corresponding detailed description of the algorithm for modeling these light-medium interactions. The developed model is employed for generation of swept-source OCT images, analysis of OCT speckle formation and interpretation of the experimental results. The obtained simulation results are compared with selected analytical solutions and experimental studies utilizing various sizes / concentrations of scattering microspheres.

  14. Flocculation kinetics mechanism and floc formation prepared by poly aluminum chloride coupled with polyacrylamide for ship ballast water.

    PubMed

    Zhou, Zhimin; Liu, Sha; Jia, Linan

    2016-01-01

    The performance of flocculants prepared by poly aluminum chloride (PAC) and polyacrylamide (PAM) on treating ballast water collected at the Dalian new port area, the evaluation depending on the values of reaction parameters, and kinetics mechanism of flocculation were investigated in this study. Accordingly, the flocculants of 0.1 g·L(-1), prepared by mixing PAC of 10% with PAM of 2.0‰, enabled the removal rate of zooplankton and phytoplankton to reach 91% in ballast water at 20 °C. Based on flocculation kinetics mechanism analysis, the efficient vortex size during stirring should be larger than the floc particles, and gradient of fluctuating velocity provide the impetus for turbulence flocculation. The results of this study could be relevant to understanding particle-floc interactions during developmental flocculation, and during application of ballast water treatment.

  15. Isoniazid-resistance conferring mutations in Mycobacterium tuberculosis KatG: catalase, peroxidase, and INH-NADH adduct formation activities.

    PubMed

    Cade, Christine E; Dlouhy, Adrienne C; Medzihradszky, Katalin F; Salas-Castillo, Saida Patricia; Ghiladi, Reza A

    2010-03-01

    Mycobacterium tuberculosis catalase-peroxidase (KatG) is a bifunctional hemoprotein that has been shown to activate isoniazid (INH), a pro-drug that is integral to frontline antituberculosis treatments. The activated species, presumed to be an isonicotinoyl radical, couples to NAD(+)/NADH forming an isoniazid-NADH adduct that ultimately confers anti-tubercular activity. To better understand the mechanisms of isoniazid activation as well as the origins of KatG-derived INH-resistance, we have compared the catalytic properties (including the ability to form the INH-NADH adduct) of the wild-type enzyme to 23 KatG mutants which have been associated with isoniazid resistance in clinical M. tuberculosis isolates. Neither catalase nor peroxidase activities, the two inherent enzymatic functions of KatG, were found to correlate with isoniazid resistance. Furthermore, catalase function was lost in mutants which lacked the Met-Tyr-Trp crosslink, the biogenic cofactor in KatG which has been previously shown to be integral to this activity. The presence or absence of the crosslink itself, however, was also found to not correlate with INH resistance. The KatG resistance-conferring mutants were then assayed for their ability to generate the INH-NADH adduct in the presence of peroxide (t-BuOOH and H(2)O(2)), superoxide, and no exogenous oxidant (air-only background control). The results demonstrate that residue location plays a critical role in determining INH-resistance mechanisms associated with INH activation; however, different mutations at the same location can produce vastly different reactivities that are oxidant-specific. Furthermore, the data can be interpreted to suggest the presence of a second mechanism of INH-resistance that is not correlated with the formation of the INH-NADH adduct.

  16. Isoniazid-resistance conferring mutations in Mycobacterium tuberculosis KatG: Catalase, peroxidase, and INH-NADH adduct formation activities

    PubMed Central

    Cade, Christine E; Dlouhy, Adrienne C; Medzihradszky, Katalin F; Salas-Castillo, Saida Patricia; Ghiladi, Reza A

    2010-01-01

    Mycobacterium tuberculosis catalase-peroxidase (KatG) is a bifunctional hemoprotein that has been shown to activate isoniazid (INH), a pro-drug that is integral to frontline antituberculosis treatments. The activated species, presumed to be an isonicotinoyl radical, couples to NAD+/NADH forming an isoniazid-NADH adduct that ultimately confers anti-tubercular activity. To better understand the mechanisms of isoniazid activation as well as the origins of KatG-derived INH-resistance, we have compared the catalytic properties (including the ability to form the INH-NADH adduct) of the wild-type enzyme to 23 KatG mutants which have been associated with isoniazid resistance in clinical M. tuberculosis isolates. Neither catalase nor peroxidase activities, the two inherent enzymatic functions of KatG, were found to correlate with isoniazid resistance. Furthermore, catalase function was lost in mutants which lacked the Met-Tyr-Trp crosslink, the biogenic cofactor in KatG which has been previously shown to be integral to this activity. The presence or absence of the crosslink itself, however, was also found to not correlate with INH resistance. The KatG resistance-conferring mutants were then assayed for their ability to generate the INH-NADH adduct in the presence of peroxide (t-BuOOH and H2O2), superoxide, and no exogenous oxidant (air-only background control). The results demonstrate that residue location plays a critical role in determining INH-resistance mechanisms associated with INH activation; however, different mutations at the same location can produce vastly different reactivities that are oxidant-specific. Furthermore, the data can be interpreted to suggest the presence of a second mechanism of INH-resistance that is not correlated with the formation of the INH-NADH adduct. PMID:20054829

  17. Analysis of Small Critical Regions of Swi1 Conferring Prion Formation, Maintenance, and Transmission.

    PubMed

    Valtierra, Stephanie; Du, Zhiqiang; Li, Liming

    2017-10-15

    Saccharomyces cerevisiae contains several prion elements, which are epigenetically transmitted as self-perpetuating protein conformations. One such prion is [SWI(+) ], whose protein determinant is Swi1, a subunit of the SWI/SNF chromatin-remodeling complex. We previously reported that [SWI(+) ] formation results in a partial loss-of-function phenotype of poor growth in nonglucose medium and abolishment of multicellular features. We also showed that the first 38 amino acids of Swi1 propagated [SWI(+)]. We show here that a region as small as the first 32 amino acids of Swi1 (Swi11-32) can decorate [SWI(+)] aggregation and stably maintain and transmit [SWI(+)] independently of full-length Swi1. Regions smaller than Swi11-32 are either incapable of aggregation or unstably propagate [SWI(+)]. When fused to Sup35MC, the [PSI(+) ] determinant lacking its PrD, Swi11-31 and Swi11-32 can act as transferable prion domains (PrDs). The resulting fusions give rise to a novel chimeric prion, [SPS(+)], exhibiting [PSI(+)]-like nonsense suppression. Thus, an NH2-terminal region of ∼30 amino acids of Swi1 contains all the necessary information for in vivo prion formation, maintenance, and transmission. This PrD is unique in size and composition: glutamine free, asparagine rich, and the smallest defined to date. Our findings broaden our understanding of what features allow a protein region to serve as a PrD. Copyright © 2017 American Society for Microbiology.

  18. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J.

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  19. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J; Wegrzyn, James E

    2012-09-18

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, and by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  20. ZnO/organic interfaces: formation of hybrid excitations and relation to charge separation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Blumstengel, Sylke; Eyer, Moritz; Hecht, Stefan; Kobin, Björn; Koch, Norbert

    2016-09-01

    ZnO is attracting significant interest as a candidate for hybrid photovoltaic and light-emitting devices. We studied electronic coupling at interfaces of ZnO with conjugated organic molecules like ladder-type oligo(phenylenes) (LOP) and NTCDA whose fundamental optical excitations are resonant to the ZnO band gap as well as with polymers employing a combination of time-resolved techniques as well as in situ differential reflectance and photoemission spectroscopy. Our studies provide evidence for the formation of hybrid charge transfer excitations (HCTE) across (Zn,Mg)O/organic interfaces. We show that by interfacial design the properties of these HCTE can be tuned and by that the charge separation process. The impact of the HCTE on photovoltaic parameters like the open circuit voltage and short circuit current is exemplarily demonstrated in (Zn,Mg)O/P3HT diodes. Furthermore, we show that by proper alignment of the frontier molecular orbitals with the semiconductor valence and conduction band edges, exciton dissociation at the interface can be switched off while exciton transfer efficiencies of up to 80 % are maintained. Thus, efficient conversion of ZnO excitons into highly emissive excitons of the organic (LOP) layer is achieved which is essential for the realization of hybrid light-emitting diodes.

  1. Correlating shaped charge performance with processing conditions and microstructure of an aluminum alloy 1100 liner enabled by a new method to arrest nascent jet formation

    NASA Astrophysics Data System (ADS)

    Scheid, James Eric

    Aluminum-lined shaped charges are used in special applications where jet and / or slug residue in the target is undesired. The three different microstructures of the aluminum liners studied herein resulted from three different manufacturing interpretations of the same design. One interpretation was completely machining the liners from best available annealed round stock. The second was to cold-forge the liners from annealed round-stock in an open-die forge to near-final dimensions, and then machine the liners to the final dimensions. The third variant in this study was to use the above forged liner, but with annealing after the machining. These three manufacturing choices resulted in significant variations in shaped charge performance. The goal of this research was to clarify the relationships between the liner metal microstructure and properties, and the corresponding shaped charge dynamic flow behavior. What began as an investigation into user-reported performance problems associated inherently with liner manufacturing processes and resultant microstructure, resolved into new understandings of the relationships between aluminum liner microstructure and shaped charge collapse kinetics. This understanding was achieved through an extensive literature review and the comprehensive characterization of the material properties of three variants of an 1100 aluminum shaped charge liner with a focus on collapse and nascent jet formation. The machined liner had a microstructure with large millimeter-sized grains and fine particles aligned in bands parallel to the charge axis. The forged liner microstructure consisted of very small one micrometer-sized (1 mum) subgrains and fine particles aligned largely in bands elongated parallel to the liner contour. The annealed liner was characterized by ten micrometer (10 mum) sized equiaxed grains with residual fine particles in the forged alignment. This characterization was enabled by the development, execution and validation of a

  2. Formulation and method for preparing gels comprising hydrous aluminum oxide

    DOEpatents

    Collins, Jack L.

    2014-06-17

    Formulations useful for preparing hydrous aluminum oxide gels contain a metal salt including aluminum, an organic base, and a complexing agent. Methods for preparing gels containing hydrous aluminum oxide include heating a formulation to a temperature sufficient to induce gel formation, where the formulation contains a metal salt including aluminum, an organic base, and a complexing agent.

  3. Overexpression of alternative oxidase gene confers aluminum tolerance by altering the respiratory capacity and the response to oxidative stress in tobacco cells.

    PubMed

    Panda, Sanjib Kumar; Sahoo, Lingaraj; Katsuhara, Maki; Matsumoto, Hideaki

    2013-06-01

    Aluminum (Al) stress represses mitochondrial respiration and produces reactive oxygen species (ROS) in plants. Mitochondrial alternative oxidase (AOX) uncouples respiration from mitochondrial ATP production and may improve plant performance under Al stress by preventing excess accumulation of ROS. We tested respiratory changes and ROS production in isolated mitochondria and whole cell of tobacco (SL, ALT 301) under Al stress. Higher capacities of AOX pathways relative to cytochrome pathways were observed in both isolated mitochondria and whole cells of ALT301 under Al stress. AOX1 when studied showed higher AOX1 expression in ALT 301 than SL cells under stress. In order to study the function of tobacco AOX gene under Al stress, we produced transformed tobacco cell lines by introducing NtAOX1 expressed under the control of the cauliflower mosaic virus (CaMV) 35 S promoter in sensitive (SL) Nicotiana tabacum L. cell lines. The enhancement of endogenous AOX1 expression and AOX protein with or without Al stress was in the order of transformed tobacco cell lines > ALT301 > wild type (SL). A decreased respiratory inhibition and reduced ROS production with a better growth capability were the significant features that characterized AOX1 transformed cell lines under Al stress. These results demonstrated that AOX plays a critical role in Al stress tolerance with an enhanced respiratory capacity, reducing mitochondrial oxidative stress burden and improving the growth capability in tobacco cells.

  4. A force sensor using nanowire arrays to understand biofilm formation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sahoo, Prasana K.; Cavalli, Alessandro; Pelegati, Vitor B.; Murillo, Duber M.; Souza, Alessandra A.; Cesar, Carlos L.; Bakkers, Erik P. A. M.; Cotta, Monica A.

    2016-03-01

    Understanding the cellular signaling and function at the nano-bio interface can pave the way towards developing next-generation smart diagnostic tools. From this perspective, limited reports detail so far the cellular and subcellular forces exerted by bacterial cells during the interaction with abiotic materials. Nanowire arrays with high aspect ratio have been used to detect such small forces. In this regard, live force measurements were performed ex-vivo during the interaction of Xylella fastidiosa bacterial cells with InP nanowire arrays. The influence of nanowire array topography and surface chemistry on the response and motion of bacterial cells was studied in detail. The nanowire arrays were also functionalized with different cell adhesive promoters, such as amines and XadA1, an afimbrial protein of X.fastidiosa. By employing the well-defined InP nanowire arrays platform, and single cell confocal imaging system, we were able to trace the bacterial growth pattern, and show that their initial attachment locations are strongly influenced by the surface chemistry and nanoscale surface topography. In addition, we measure the cellular forces down to few nanonewton range using these nanowire arrays. In case of nanowire functionalized with XadA1, the force exerted by vertically and horizontally attached single bacteria on the nanowire is in average 14% and 26% higher than for the pristine array, respectively. These results provide an excellent basis for live-cell force measurements as well as unravel the range of forces involved during the early stages of bacterial adhesion and biofilm formation.

  5. Determination of boron at sub-ppm levels in uranium oxide and aluminum by hyphenated system of complex formation reaction and high-performance liquid chromatography (HPLC).

    PubMed

    Rao, Radhika M; Aggarwal, Suresh K

    2008-04-15

    Boron, at sub-ppm levels, in U3O8 powder and aluminum metal, was determined using complex formation and dynamically modified reversed-phase high-performance liquid chromatography (RP-HPLC). Curcumin was used for complexing boron extracted with 2-ethyl-1,3-hexane diol (EHD). Separation of complex from excess reagent and thereafter its determination using the online diode array detector (DAD) was carried out by HPLC. Calibration curve was found to be linear for boron amounts in the sample ranging from 0.02 microg to 0.5 microg. Precision of about 10% was achieved for B determination in samples containing less than 1 ppmw of boron. The values obtained by HPLC were in good agreement with the data available from other analytical techniques. The precision in the data obtained by HPLC was much better compared to that reported by other techniques. The present hyphenated methodology of HPLC and complex formation reaction is interesting because of cost performance, simplicity, versatility and availability when compared to other spectroscopic techniques like ICP-MS and ICP-AES.

  6. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  7. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  8. Reactively Deposited Aluminum Oxide and Fluoropolymer Filled Aluminum Oxide Protective Coatings for Polymers

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.; Hunt, Jason

    1995-01-01

    Reactive ion beam sputter deposition of aluminum simultaneous with low energy arrival of oxygen ions at the deposition surface enables the formation of highly transparent aluminum oxide films. Thick (12 200 A), adherent, low stress, reactively deposited aluminum oxide films were found to provide some abrasion resistance to polycarbonate substrates. The reactively deposited aluminum oxide films are also slightly more hydrophobic and more transmitting in the UV than aluminum oxide deposited from an aluminum oxide target. Simultaneous reactive sputter deposition of aluminum along with polytetrafluoroethylene (PTFE Teflon) produces fluoropolymer-filled aluminum oxide films which are lower in stress, about the same in transmittance, but more wetting than reactively deposited aluminum oxide films. Deposition properties, processes and potential applications for these coatings will be discussed.

  9. In situ pH measurement during the formation of conversion coatings on an aluminum alloy (AA2024).

    PubMed

    Li, Liangliang; Desouza, Annika Laura; Swain, Greg M

    2013-08-07

    The measurement of interfacial pH change is important for understanding the formation mechanism of conversion coatings that are used to protect metals from corrosion. In this work, we used a tungsten microelectrode to measure the interfacial pH change near the surface of an aluminium alloy (AA2024) during the formation of two conversion coatings: (i) a trivalent chromium pretreatment (TCP) and (ii) a Ti-based, non-chromium-containing coating. The tungsten microelectrode exhibited an open circuit potential (OCP) that changed linearly as a function of the solution pH with a slope of -64 mV per pH. The microelectrode was positioned near the AA2024-T3 surface and its potential was measured as a function of time along with the OCP of the alloy sample during formation of the two coatings. The microelectrode exhibited a negative shift in potential immediately upon initiation of the coating formation, consistent with a significant increase in the interfacial pH of 2-6 units depending on the coating system. The pH increase is attributed to proton-consuming cathodic reactions that occur on the alloy surface once the passivating oxide layer is dissolved: hydrogen evolution and oxygen reduction. The increased pH causes the hydrolysis of the soluble fluorometalate precursor species in the baths, which precipitate forming a hydrated metal oxide coating (e.g., ZrO2·nH2O).

  10. An S-adenosyl Methionine Synthetase (SAMS) Gene from Andropogon virginicus L. Confers Aluminum Stress Tolerance and Facilitates Epigenetic Gene Regulation in Arabidopsis thaliana

    PubMed Central

    Ezaki, Bunichi; Higashi, Aiko; Nanba, Norie; Nishiuchi, Takumi

    2016-01-01

    Candidate clones which conferred Al tolerance to yeast transformants (TFs) were obtained from a cDNA library derived from a highly Al-tolerant poaceae, Andropogon virginicus L. One such clone, AL3A-4, encoded an S-adenosyl methionine synthetase (SAMS) gene. A full-length cDNA was obtained by 5′-RACE, designated AvSAMS1, and introduced into Arabidopsis thaliana to investigate its biological functions under Al stress. Two TF plant lines both showed higher tolerance than the Col-0 ecotype (non-TF) not only for Al stress, but also for Cu, Pb, Zn and diamide stresses, suggesting the AvSAMS1 was a multiple tolerance gene. More than 40 of A. thaliana Al response-genes (Al induced genes and Al repressed genes) were selected from microarray results and then used for investigations of DNA or histone methylation status under Al stress in Col-0 and the AvSAMS1 TF line. The results indicated that Al stress caused alterations of methylation status in both DNA and histone H3 (H3K4me3 and H3K9me3) and that these alterations were different between the AvSAMS1 TF and Col-0, suggesting the differences were AvSAMS1-gene dependent. These results suggested the existence of AvSAMS1-related epigenetic gene-regulation under Al stress. PMID:27877178

  11. Silico-ferrite of Calcium and Aluminum (SFCA) Iron Ore Sinter Bonding Phases: New Insights into Their Formation During Heating and Cooling

    NASA Astrophysics Data System (ADS)

    Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Kimpton, Justin A.

    2012-12-01

    The formation of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter phases during heating and cooling of synthetic iron ore sinter mixtures in the range 298 K to 1623 K (25 °C to 1350 °C) and at oxygen partial pressure of 5 × 10-3 atm has been characterized using in situ synchrotron X-ray diffraction. SFCA and SFCA-I are the key bonding phases in iron ore sinter, and an improved understanding of their formation mechanisms may lead to improved efficiency of industrial sintering processes. During heating, SFCA-I formation at 1327 K to 1392 K (1054 °C to 1119 °C) (depending on composition) was associated with the reaction of Fe2O3, 2CaO·Fe2O3, and SiO2. SFCA formation (1380 K to 1437 K [1107 °C to 1164 °C]) was associated with the reaction of CaO·Fe2O3, SiO2, and a phase with average composition 49.60, 9.09, 0.14, 7.93, and 32.15 wt pct Fe, Ca, Si, Al, and O, respectively. Increasing Al2O3 concentration in the starting sinter mixture increased the temperature range over which SFCA-I was stable before the formation of SFCA, and it stabilized SFCA to a higher temperature before it melted to form a Fe3O4 + melt phase assemblage (1486 K to 1581 K [1213 °C to 1308 °C]). During cooling, the first phase to crystallize from the melt (1452 K to 1561 K [1179 °C to 1288 °C]) was an Fe-rich phase, similar in composition to SFCA-I, and it had an average composition 58.88, 6.89, 0.82, 3.00, and 31.68 wt pct Fe, Ca, Si, Al, and O, respectively. At lower temperatures (1418 K to 1543 K [1145 °C to 1270 °C]), this phase reacted with melt to form SFCA. Increasing Al2O3 increased the temperature at which crystallization of the Fe-rich phase occurred, increased the temperature at which crystallization of SFCA occurred, and suppressed the formation of Fe2O3 (1358 K to 1418 K [1085 °C to 1145 °C]) to lower temperatures.

  12. First principles pseudopotential calculations on aluminum and aluminum alloys

    SciTech Connect

    Davenport, J.W.; Chetty, N.; Marr, R.B.; Narasimhan, S.; Pasciak, J.E.; Peierls, R.F.; Weinert, M.

    1993-12-31

    Recent advances in computational techniques have led to the possibility of performing first principles calculations of the energetics of alloy formation on systems involving several hundred atoms. This includes impurity concentrations in the 1% range as well as realistic models of disordered materials (including liquids), vacancies, and grain boundaries. The new techniques involve the use of soft, fully nonlocal pseudopotentials, iterative diagonalization, and parallel computing algorithms. This approach has been pioneered by Car and Parrinello. Here the authors give a review of recent results using parallel and serial algorithms on metallic systems including liquid aluminum and liquid sodium, and also new results on vacancies in aluminum and on aluminum-magnesium alloys.

  13. Starting mechanisms and dynamics of bubble formation induced by a Ho:Yttrium aluminum garnet laser in water

    NASA Astrophysics Data System (ADS)

    Frenz, Martin; Könz, Flurin; Pratisto, Hans; Weber, Heinz P.; Silenok, Alexander S.; Konov, Vitaly I.

    1998-12-01

    The starting mechanisms and dynamics of laser-induced bubble formation at a submerged fiber tip in distilled water were experimentally investigated using pressure measurements and fast flash videography. A fiber guided Ho:YAG laser operating in the free running (τ=200 μs) and Q-switched (τ=45 ns) mode at a wavelength of λ=2.12 μm was used as a light source. It is shown that the beam profile at the distal fiber tip (multimode fiber d=300 μm) exhibits hot spots that result in an inhomogeneous temperature distribution in the heated water volume. Depending on the laser irradiance, three different bubble formation processes are distinguished: bubble formation by heating, by rarefraction (cavitation), and by a combination of these two processes. For laser irradiances of less than 0.5 MW/ cm2 bubble formation takes place at temperatures near the critical point of water (T=280 °C). A rapid decrease in the threshold temperature for bubble formation was found for laser irradiances between 0.5 and 1 MW/cm 2. At laser irradiances higher than 3 MW/cm2, microbubbles with radii of up to 20 μm were formed at the front of the laser pulse even though the average water temperature was far below 100 °C. The water temperature distribution during the laser pulse was determined by numerical simulation. Simultaneous pressure measurements revealed that each subablative laser spike induces a bipolar pressure transient. The onset of the bubble expansion was found to be correlated with a characteristic pressure increase that can be used for on-line monitoring of the ablation process. The distortion of the temporal profile of the pressure wave is shown to be an effect of diffraction. The reduction of pressure by the negative part of the bipolar pressure transients leads to a lowering of the evaporation pressure and therefore to the initiation of bubbles by cavitation. With increasing irradiance this mechanism becomes more efficient.

  14. The Changing Academic Profession in Asia: The Formation, Work, Academic Productivity, and Internationalization of the Academy. Report of the International Conference on the Changing Academic Profession Project, 2014. RIHE International Seminar Reports. No. 22

    ERIC Educational Resources Information Center

    Research Institute for Higher Education, Hiroshima University, 2015

    2015-01-01

    The International Conference on the Changing Academic Profession Project convened in Hiroshima City, Japan, January 24-25, 2014. It was jointly hosted by the Research Institutes of Higher Education at Hiroshima and Kurashiki Sakuyo Universities. The theme of the conference was "The Changing Academic Profession in Asia: The Formation, Work,…

  15. Microstructures and formation history of melilite-rich calcium-aluminum-rich inclusions from the ALHA77307 CO3.0 chondrite

    NASA Astrophysics Data System (ADS)

    Han, Jangmi; Brearley, Adrian J.

    2017-03-01

    We have studied four melilite-rich calcium-aluminum-rich inclusions (CAIs) from the Allan Hills A77307 CO3.0 chondrite using transmission electron microscopy with the focused ion beam sample preparation technique. This type of CAI represents one of the dominant types of refractory inclusions in CO3 chondrites. Individual melilite-rich CAIs 04-07 record complex formational histories involving high-temperature gas-solid condensation that occurred under both equilibrium and disequilibrium conditions. CAI 04 contains two texturally- and compositionally-distinct occurrences of perovskite: fine-grained perovskite within a melilite-rich core and aggregates of perovskite grains that surround the core. The perovskite in the core was probably involved in a disequilibrium reaction with early equilibrium condensates (e.g., melilite and spinel) and a nebular gas to form Al-Ti-rich diopside, followed by a later condensation of the perovskite aggregates under equilibrium conditions. CAI 05 has a compact melilite-rich core surrounded by a porous mantle, and likely formed by at least two different condensation events under equilibrium and disequilibrium conditions. In CAI 06, complex intergrowth layers of spinel and diopside surrounding a melilite-rich core indicate disequilibrium reaction of spinel and melilite with a nebular gas to form Al-Ti-rich diopside following core formation by equilibrium condensation. CAI 07 is dominated by melilite with a narrow compositional range and equilibrated textures, suggesting its formation by equilibrium condensation over a limited temperature range. Collectively, we infer that the melilite-rich inclusions formed by a generalized sequence of high-temperature gas-solid condensation that involved: (1) formation of CAI cores by aggregation of primary equilibrium condensates (i.e., perovskite, spinel, and melilite), (2) back-reactions of the primary core minerals with a nebular gas under disequilibrium conditions, forming diopside that evolves in

  16. Formation of ordered films of axially bridged aluminum phthalocyanine [(tBu){sub 4}PcAl]{sub 2}O via magnetic field-induced reaction

    SciTech Connect

    Basova, Tamara Berezin, Aleksei; Nadolinny, Vladimir; Peisert, Heiko; Chassé, Thomas; Banimuslem, Hikmat; Hassan, Aseel

    2013-11-28

    The μ-(oxo)bis[tetra-tert-butylphthalocyaninato] aluminum(III) [(tBu){sub 4}PcAl]{sub 2}O films with the crystallites oriented preferably in one direction were obtained via chemical transformation of tetra-tert-butylsubstituted chloroaluminum(III) phthalocyanine (tBu){sub 4}PcAlCl film upon its annealing in magnetic field. A comparative analysis of the influence of post-deposition annealing process without and under applied magnetic field of 1 T, on the orientation and morphology of (tBu){sub 4}PcAlCl and [(tBu){sub 4}PcAl]{sub 2}O films, has been carried out by the methods of UV-vis, Infrared and Raman spectroscopies, XRD as well as atomic force microscopy. The formation of [(tBu){sub 4}PcAl]{sub 2}O films with elongated crystallites having preferential orientation was observed upon heating of the films in magnetic field while annealing without magnetic field under the same conditions does not demonstrate any effect on the structure and morphology of these films. The reasons of the sensitivity of this reaction to the presence of such magnetic field is discussed and studied by electronic paramagnetic resonance spectroscopy.

  17. A Thermodynamic Study of Metastable Al-Fe Phase Formation in Direct Chill (DC)-Cast Aluminum Alloy Ingots

    NASA Astrophysics Data System (ADS)

    Aliravci, Celil A.; Gruzleski, John E.; Pekgüleryüz, Mihriban Ö.

    In direct-chill (DC)-cast lxxx-and 5xxx-series Al sheet-ingots, the presence of mainly Fe and some Si, and cooling rates increasing from formation of metastable intermetallic Al6Fe and AlmFe compounds in addition to the stable Al3Fe, and hence the fir-tree defect. Since the Al-Fe and Al-Fe-Si phase diagrams are not useful in predicting the metastable phase formation, a binary phase diagram study was conducted to calculate the Al-Al6Fe and Al-AlmFe metastable phase equilibria using a thermodynamic software and an Al-alloy database. The Al-Al3Fe phase diagram was calculated using the existing Gibbs energy data which gives the eutectic point at 1.85wt% Fe and the eutectic temperature as 654°C. The missing Gibbs energy data for the metastable phases were estimated using substitutional and graphical methods and the phase diagrams were calculated. In the Al-Al6Fe phase diagram, the eutectic temperature is depressed from 654°C (equilibrium) to 648°C and the eutectic point is shifted from 1.85wt% Fe to 3.4wt% Fe. In the Al-AlmFe phase

  18. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  19. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  20. A CRITICAL EXAMINATION OF THE X-WIND MODEL FOR CHONDRULE AND CALCIUM-RICH, ALUMINUM-RICH INCLUSION FORMATION AND RADIONUCLIDE PRODUCTION

    SciTech Connect

    Desch, S. J.; Morris, M. A.; Connolly, H. C.; Boss, Alan P.

    2010-12-10

    Meteoritic data, especially regarding chondrules and calcium-rich, aluminum-rich inclusions (CAIs), and isotopic evidence for short-lived radionuclides (SLRs) in the solar nebula, potentially can constrain how planetary systems form. Interpretation of these data demands an astrophysical model, and the 'X-wind' model of Shu et al. and collaborators has been advanced to explain the origin of chondrules, CAIs, and SLRs. It posits that chondrules and CAIs were thermally processed <0.1 AU from the protostar, then flung by a magnetocentrifugal outflow to the 2-3 AU region to be incorporated into chondrites. Here we critically examine key assumptions and predictions of the X-wind model. We find a number of internal inconsistencies: theory and observation show no solid material exists at 0.1 AU; particles at 0.1 AU cannot escape being accreted into the star; particles at 0.1 AU will collide at speeds high enough to destroy them; thermal sputtering will prevent growth of particles; and launching of particles in magnetocentrifugal outflows is not modeled, and may not be possible. We also identify a number of incorrect predictions of the X-wind model: the oxygen fugacity where CAIs form is orders of magnitude too oxidizing, chondrule cooling rates are orders of magnitude lower than those experienced by barred olivine chondrules, chondrule-matrix complementarity is not predicted, and the SLRs are not produced in their observed proportions. We conclude that the X-wind model is not relevant to chondrule and CAI formation and SLR production. We discuss more plausible models for chondrule and CAI formation and SLR production.

  1. Protective coating for copper in aluminum heat exchangers

    NASA Technical Reports Server (NTRS)

    Avazian, R.

    1978-01-01

    Application of ultrathin layer of molybdenum disulfied coating to copper tubing permits utilization of tubing in cast-aluminum heat exchangers. Coating prevents formation of copper/aluminum eutectic, but does not impede heat transfer.

  2. Formation Mechanism of SiO2-Type Inclusions in Si-Mn-Killed Steel Wires Containing Limited Aluminum Content

    NASA Astrophysics Data System (ADS)

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin

    2015-10-01

    The origin, formation mechanism, and evolution of SiO2-type inclusions in Si-Mn-killed steel wires were studied by pilot trials with systematical samplings at the refining ladle, casting tundish, as-cast bloom, reheated bloom, and hot-rolled rods. It was found that the inclusions in tundish were well controlled in the low melting point region. By contrast, MnO-SiO2-Al2O3 inclusions in the as-cast bloom were with compositions located in the primary region of SiO2, and most CaO-SiO2-Al2O3-MnO inclusions lied in primary phase region of anorthite. Therefore, precipitation of SiO2 particles in MnO-SiO2-Al2O3 inclusions can be easier than in CaO-SiO2-Al2O3-MnO inclusions to form dual-phase inclusions in the as-cast bloom. Thermodynamic calculation by the software FactSage 6.4 (CRCT-ThermFact Inc., Montréal, Canada) showed that mass transfer between liquid steel and inclusions resulted in the rise of SiO2 content in inclusions from tundish to as-cast bloom and accelerated the precipitation of pure SiO2 phase in the formed MnO-SiO2-Al2O3 inclusions. As a result, the inclusions characterized by dual-phase structure of pure SiO2 in MnO-SiO2-Al2O3 matrix were observed in both as-cast and reheated blooms. Moreover, the ratio of such dual-phase SiO2-type inclusions witnessed an obvious increase from 0 to 25.4 pct before and after casting, whereas it changed little during the reheating and rolling. Therefore, it can be reasonably concluded that they were mainly formed during casting. Comparing the evolution of the inclusions composition and morphology in as-cast bloom and rolled products, a formation mechanism of the SiO2-type inclusions in wire rods was proposed, which included (1) precipitation of SiO2 in the formed MnO-SiO2-Al2O3 inclusion during casting and (2) solid-phase separation of the undeformed SiO2 precipitation from its softer MnO-SiO2-Al2O3 matrix during multipass rolling.

  3. Aluminum phosphide

    Integrated Risk Information System (IRIS)

    Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  4. Magnetic field threshold for thermal plasma formation from an aluminum surface pulsed to multi-megagauss magnetic field

    NASA Astrophysics Data System (ADS)

    Awe, Thomas

    2010-11-01

    The first measurement of the thermal ionization threshold of a thick-metal surface by pulsed multi-megagauss magnetic field is reported. Whether plasma should form from intensely ohmically heated thick metal has been of interest since at least 1959, when Fowler et al. first reported producing fields above 10 MG. Plasma formation from thick metal is uncertain, even for megagauss field, because fresh, cold, high conductivity metal persists within, reducing the electric field, current density, and ohmic heating at the surface. The phase-state of thick metal subjected to ultra-high field has been examined by pulsing Al rods of initial diameter 0.50-2.00 mm to 1.0 MA peak current in 100 ns. Experiments accessed the surface-heating regime, where the magnetic penetration depth is less than the conductor radius, and current flows in a skin layer. Shot hardware with novel electrical contacts mitigated or eliminated the non-thermal precursor plasma produced by electric-field-driven electron avalanche and arcing electrical contacts in earlier experiments. Rod surfaces were examined with time-resolved imaging, visible and EUV radiometry and spectroscopy, and laser shadowgraphy. For magnetic field rise rates from 30-80 MG/μs, thermal plasma forms from 6061-alloy Al when the surface field reaches the threshold level of 2.2 MG, in qualitative agreement with simulation results by Garanin et al. [J. Appl. Mech. Tech. Phys. 46, 153 (2005)] which suggest that a thick Cu surface will ionize when the imposed magnetic field reaches 1.5-3 MG. Measurements of the time-evolution of the surface temperature, Al expansion rate, and ionization state, as functions of applied field, significantly constrain the choice of models used in rad-MHD simulations.

  5. Theoretical study of the formation mechanism of laser-induced aluminum plasmas using Nd:YAG fundamental, second or third harmonics

    NASA Astrophysics Data System (ADS)

    Morel, Vincent; Bultel, Arnaud

    2014-04-01

    The Collisional-Radiative model CoRaM-Al is implemented in a 0D numerical code in the purpose of describing the formation of the plasma resulting from the interaction between a 4 ns Nd:YAG laser pulse and an aluminum sample in vacuum. The influence of the first three harmonics at 355 nm, 532 nm and 1064 nm is studied. In each case, the fluence value is set equal to the threshold above which a phase explosion takes place. The sample surface temperature is therefore limited to the critical temperature (6700 K). The solid → gas transition is classically treated by using the Hertz-Knudsen law. The species considered in CoRaM-Al are Al, Al+, Al2 +, Al3 + and free electrons. They are in thermochemical non-equilibrium at different temperatures. Each state behaves freely owing to electron impact induced excitation and ionization, elastic collisions, Multiphoton Ionization (MPI), Inverse Bremsstrahlung (IB), thermal Bremsstrahlung, and spontaneous emission. The results show that MPI and IB play a complementary role in the heating process of electrons. In the ultraviolet and visible cases, the increase in electron temperature is mainly due to multiphoton ionization before the maximum irradiance. The electron temperature does not exceed 9000 K. The heavy particle temperature mainly results from the surface temperature. Conversely, in the infrared case, electron temperature strongly increases after the maximum irradiance owing to inverse Bremsstrahlung. Electrons then give a part of their energy for the benefit of heavy particles, which leads to the increase in their temperature. The electron number density reaches its maximum during the laser pulse with a value of the order of 1025 m- 3 and the electron temperature exceeds 13,000 K. A maximum of the ionization degree close to 0.2 is thus obtained at 1064 nm.

  6. Expanding the Availability of Lightweight Aluminum Alloy Armor Plate Procured From Detailed Military Specifications

    DTIC Science & Technology

    2012-07-01

    elements was eventually designated 17S ( 2017 ) and is the progenitor of the 2 series of aluminum alloys . Alcoa obtained the rights to produce...Expanding the Availability of Lightweight Aluminum Alloy Armor Plate Procured From Detailed Military Specifications by Kevin Doherty...International Conference on Aluminum Alloys (ICAA13), pp. 541–546, Pittsburgh, PA, 3–7 June 2012. Approved for public

  7. Interaction of aluminum projectiles with quartz sand in impact experiments: Formation of khatyrkite (CuAl2) and reduction of SiO2 to Si

    NASA Astrophysics Data System (ADS)

    Hamann, Christopher; Stöffler, Dieter; Reimold, Wolf Uwe

    2016-11-01

    We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9 and 6.5 km/s and ∼41 and 48 GPa, respectively. Shocked particles (;impact melt particles;) coated with thin crusts of molten projectile material were recovered from the floors of the ca. 33-cm-diameter craters and the respective ejecta blankets. Through petrographic and chemical (optical microscopy, FE-EMPA, SEM-EDX, and XRF) analysis we show that these particles have a layered structure manifested in distinct layers of decreasing shock metamorphism. These can be characterized by the following physical and chemical reactions and alteration products: (i) complete melting and subsequent recrystallization of the projectile, forming a distinct crystallization texture in the fused metal crust; (ii) projectile-target mixing, involving a redox reaction between Cu-bearing Al alloy und SiO2, leading to formation of khatyrkite (CuAl2), Al2O3 melt, euhedral silicon crystals, and spherical droplets of silicon; (iii) melting of quartz to lechatelierite and formation of planar deformation features in relic quartz grains; and (iv) shock lithification of quartz grains with fracturing of grains, grain-boundary melting, planar deformation features, and complete loss of porosity. To our knowledge, this is the first report of khatyrkite formed experimentally in hypervelocity impact experiments. These results have implications for the understanding of a similar redox reaction between Al-Cu metal and siliceous impact melt recently postulated for the Khatyrka CV3 carbonaceous chondrite. Moreover, these results bear on the processes that lead to layers of regolith on the surfaces of planetary bodies without atmospheres, such as asteroids in the main belt (e.g., 4 Vesta), and on the Moon. Specifically, impacts of mm

  8. Electron Diffraction Evidence for the Ordering of Excess Nickel Atoms by Relation to Stoichiometry in Nickel-Rich Beta'-Nial Formation of a Nickel-Aluminum (Ni2al) Superlattices

    NASA Technical Reports Server (NTRS)

    Reynaud, F.

    1988-01-01

    In electron diffraction patterns of nickel-rich beta-NiAl alloys, many anomalies are observed. One of these is the appearance of diffuse intensity maxima between the reflexions of the B2 structure. This is explained by the short-range ordering of the excess nickel atoms on the simple cubic sublattice occupied only by aluminum atoms in the stoichiometric, perfectly ordered NiAl alloy. After annealing Ni 37.5 atomic percent Al and Ni 37.75 atomic percent Al for 1 week at 300 and 400 C, the diffuse intensity maxima transformed into sharp superstructure reflexions. These reflexions are explained by the formation of the four possible variants of an ordered hexagonal superstructure corresponding to the Ni2Al composition. This structure is closely related to the Ni2Al3 structure (same space group) formed by the ordering of vacancies on the nickel sublattice in aluminum-rich beta-NiAl alloys.

  9. Crust Formation in Aluminum Cells

    NASA Astrophysics Data System (ADS)

    Oedegard, R.; Roenning, S.; Rolseth, S.; Thonstad, J.

    1985-11-01

    This paper examines the catalytic effects offlourides on the ϒ→α-Al2O3 phase transformation by heat treating commercial alumina samples with 2wt% additions of different flouride compounds. The various additives were ranked according to their effect on transformation temperature. Experiments were conducted to explain the high temperature coherence of crusts. The findings indicate that an alumina network is formed during ϒ→α phase transformation, which reinforces the crust on top of the cryolite bath.

  10. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  11. Specific features of aluminum nanoparticle water and wet air oxidation

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, Aleksandr S.; Glazkova, Elena A.; Svarovskaya, Natalia V.; Bakina, Olga V.; Kazantsev, Sergey O.; Lerner, Marat I.

    2015-10-01

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation.

  12. Specific features of aluminum nanoparticle water and wet air oxidation

    SciTech Connect

    Lozhkomoev, Aleksandr S. Glazkova, Elena A. Svarovskaya, Natalia V. Bakina, Olga V. Kazantsev, Sergey O. Lerner, Marat I.

    2015-10-27

    The oxidation processes of the electrically exploded aluminum nanopowders in water and in wet air are examined in the paper. The morphology of the intermediate reaction products of aluminum oxidation has been studied using the transmission electron microscopy. It was shown that the aluminum nanopowder water oxidation causes the formation of the hollow spheres with mesoporous boehmite nanosheets coating. The wedge-like bayerite particles are formed during aluminum nanopowder wet air oxidation.

  13. Design for aluminum recycling

    SciTech Connect

    Not Available

    1993-10-01

    This article describes the increasing use of aluminum in automobiles and the need to recycle to benefit further growth of aluminum applications by assuring an economical, high-quality source of metal. The article emphasizes that coordination of material specifications among designers can raise aluminum scrap value and facilitate recycling. Applications of aluminum in automobile construction are discussed.

  14. Cryomilled Aluminum Stabilized by Diamondoid Nanoparticles

    NASA Astrophysics Data System (ADS)

    Maung, Khinlay

    Nanocrystalline aluminum powder with an average grain size of 22nm was prepared via cryomilling. Hot Isostatic Pressing was used to consolidate the powder followed by hot extrusion to homogenize the consolidated material. The high homologous temperature processes tend to increase the average grain diameter beyond the nanoscle classification, which is less than 100 nm. Diamantane was added during cryomilling to enhance the thermal stability in nanocrystalline aluminum. The thermal stability test data show that aluminum reinforced with 1 wt% diamantane exhibit two to three fold better thermal stability than non-reinforced aluminum when annealed at 773K (0.84 Tm) for ten hours. A similar trend is shown for the samples consolidated at 693K. This finding is explained through Burke's model for grain growth in materials containing secondary particles to inhibit grain boundary motion. The mechanical properties of cryomilled aluminum stabilized by 0.5 wt% and 1 wt% diamantane particles are compared with cryomilled commercial purity (CP) aluminum with no diamantane after high strain rate deformation (trap extrusion). The grain size of cryomilled CP aluminum is 0.6 to 1.2 times larger than the samples containing diamantane. In contrast to Hall-petch predictions, cryomilled aluminum with diamantane has relatively lower flow stress while demonstrating a 2.7-3.7 time higher ductility compared to cryomilled CP aluminum. Possible reasons for this behavior are suggested in mechnical property section. A combination of higher temperature and pressure resulted in formation of Aluminum tris (Al(C9H6NO)3) precipitates from diamantane in the cryomilled aluminum matrix. The precipitates were formed during trap extrusion process but only seen in samples containing 1 wt% diamantane and HIP'ed at 521°C. Therefore, the HIP'ng temperature plays an important role in formation of these precipitates.

  15. Friction stir processing of an aluminum-magnesium alloy with pre-placing elemental titanium powder: In-situ formation of an Al{sub 3}Ti-reinforced nanocomposite and materials characterization

    SciTech Connect

    Khodabakhshi, F.; Simchi, A.; Kokabi, A.H.; Gerlich, A.P.

    2015-10-15

    A fine-grained Al–Mg/Al{sub 3}Ti nanocomposite was fabricated by friction stir processing (FSP) of an aluminum-magnesium (AA5052) alloy with pre-placed titanium powder in the stirred zone. Microstructural evolutions and formation of intermetallic phases were analyzed by optical and electron microscopic techniques across the thickness section of the processed sheets. The microstructure of the nanocomposite consisted of a fine-grained aluminum matrix (1.5 µm), un-reacted titanium particles (<40 µm) and reinforcement particles of Al{sub 3}Ti (<100 nm) and Mg{sub 2}Si (<100 nm). Detailed microstructural analysis indicated solid-state interfacial reactions between the aluminum matrix and micro-sized titanium particles to form Al{sub 3}Ti intermetallic phase. The hard inclusions were then fractured and re-distributed in the metal matrix by the severe thermo-mechanical conditions imposed by FSP. Evaluation of mechanical properties by hardness measurement and uniaxial tensile test determined significant enhancement in the mechanical strength (by 2.5 order of magnetite) with a high ductility (~22%). Based on a dislocation-based model analysis, it was suggested that the strength enhancement was governed by grain refinement and the presence of hard inclusions (4 vol%) in the metal matrix. Fractographic studies also showed a ductile-brittle fracture mode for the nanocomposite compared with fully ductile rupture of the annealed alloy as well as the FSPed specimen without pre-placing titanium particles. - Highlights: • FSP was employed to fabricate in situ nanocomposite. • The AA5052 Al alloy with pre-placed micro-sized Ti particles were utilized. • The structural analysis was revealed that the in situ formation of Al{sub 3}Ti nanophase. • The SZ grain structure was refined by PSN and ZHP mechanisms during DRX. • Hardness and tensile strength were improved up to ~2.5 times with a good ductility.

  16. Influence of Aluminum Coating and Diffusion Affecting Additives on Dissimilar Laser Joining of Steel and Aluminum

    NASA Astrophysics Data System (ADS)

    Bergmann, J. P.; Stambke, M.; Schmidt, S.

    Steel as well as aluminum play an essential role for multi-material construction in the field of lightweight design. However, the thermal metallurgical joining of these materials is difficult due to their different physical properties and the formation of intermetallic phases. This paper describes investigations on laser joining of aluminum plated steel with aluminum. Furthermore examinations with additives acting as diffusion barriers were carried out. The results indicate that the aluminum coating is advantageous for the joint. The growth of intermetallic phases can be reduced by application of carbon and tungsten to the steel sheet tip.

  17. Occupational exposure to aluminum and its biomonitoring in perspective.

    PubMed

    Riihimäki, Vesa; Aitio, Antero

    2012-11-01

    Exposure to aluminum at work is widespread, and people are exposed to several species of aluminum, which differ markedly as to the kinetics and toxicity. Especially welding of aluminum is widely applied and continuously expanding. Inhalation of fine particles of sparsely soluble aluminum results in the retention of deposited particles in the lungs. From the lungs, aluminum is released to the blood and distributed to bones and the brain, and excreted to urine. Soluble aluminum compounds are not accumulated in the lungs. Neurotoxicity is the critical effect of exposure to sparsely soluble aluminum compounds. Studies on workers exposed to aluminum welding fumes have revealed disturbances of cognitive processes, memory and concentration, and changes in mood and EEG. Early pulmonary effects have been observed among aluminum powder-production workers using high-resolution computed tomography. The primary objective of aluminum biomonitoring (BM) is to help prevent the formation of aluminum burden in the lungs and thereby to prevent harmful accumulation of aluminum in target organs. BM of aluminum can be effectively used for this purpose in the production/use of aluminum powders, aluminum welding, as well as plasma cutting, grinding, polishing and thermal spraying of aluminum. BM of aluminum may also be similarly useful in the smelting of aluminum and probably in the production of corundum. BM can help identify exposed individuals and roughly quantitate transient exposure but cannot predict health effects in the production/use of soluble aluminum salts. For urinary aluminum (U-Al) we propose an action limit of 3 µmol/L, corrected to a relative density of 1.021, in a sample collected preshift after two days without occupational exposure, and without use of aluminum-containing drugs. This value corresponds roughly to 2.3 µmol/g creatinine. Compliance with this limit is expected to protect the worker against the critical effect of aluminum in exposure to sparsely soluble

  18. Chemical synthesis of aluminum nanoparticles

    NASA Astrophysics Data System (ADS)

    Ghanta, Sekher Reddy; Muralidharan, Krishnamurthi

    2013-06-01

    An alternate synthetic route has been described for the production of aluminum nanoparticles (Al-NPs). These Al-NPs were obtained through a reduction of aluminum acetylacetonate [Al(acac)3] by lithium aluminum hydride (LiAlH4) in mestitylene at 165 °C. The side products were removed by repeated washing with dry, ice cold methanol and the reaction mixture was filtered to obtain gray-colored Al-NPs. The synthesized nanoparticles were characterized by Powder X-ray diffraction pattern and 27Al-MAS-NMR spectrum. The X-ray diffraction pattern confirmed the formation of face-centered cubic (fcc) form of aluminum. The size and morphology were investigated by scanning electron microscope and transmission electron microscope which showed particle of varying shapes with size ranging from 50 to 250 nm. The weight loss from the nanoparticles was studied by thermo gravimetric analysis which indicated that the nanoparticles were tightly bound with an unknown amorphous organic residue which cannot be removed by simple washing. The carbonaceous residue might be outcome of the decomposition of acac ligand which was responsible in stabilizing aluminum nanoparticles.

  19. Aluminum-based metal-air batteries

    DOEpatents

    Friesen, Cody A.; Martinez, Jose Antonio Bautista

    2016-01-12

    Provided in one embodiment is an electrochemical cell, comprising: (i) a plurality of electrodes, comprising a fuel electrode that comprises aluminum and an air electrode that absorbs gaseous oxygen, the electrodes being operable in a discharge mode wherein the aluminum is oxidized at the fuel electrode and oxygen is reduced at the air electrode, and (ii) an ionically conductive medium, comprising an organic solvent; wherein during non-use of the cell, the organic solvent promotes formation of a protective interface between the aluminum of the fuel electrode and the ionically conductive medium, and wherein at an onset of the discharge mode, at least some of the protective interface is removed from the aluminum to thereafter permit oxidation of the aluminum during the discharge mode.

  20. Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores

    USGS Publications Warehouse

    Meeker, G.P.

    1995-01-01

    Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author

  1. Beta4 integrin-dependent formation of polarized three-dimensionalarchitecture confers resistance to apoptosis in normal and malignantmammary epithelium

    SciTech Connect

    Weaver, Valerie M.; Lelievre, Sophie; Lakins, Johnathon N.; Chrenek, Micah A.; Jones, Jonathan C.R.; Giancotti, Filippo; Werb, Zena; Bissell, Mina J.

    2002-08-27

    Tumor cells can evade chemotherapy by acquiring resistanceto apoptosis. We investigated the molecular mechanism whereby malignantand nonmalignant mammary epithelial cells become insensitive toapoptosis. We show that regardless of growth status formation ofpolarized, three-dimensional structures driven by basement membraneconfers protection to apoptosis in both nonmalignant and malignantmammary epithelial cells. By contrast, irrespective of their malignantstatus, nonpolarized structures are sensitive to induction of apoptosis.Resistance to apoptosis requires ligation of beta4 integrins, whichregulates tissue polarity, hemidesmosome formation and NFkB activation.Expression of beta4 integrin that lacks the hemidesmosome targetingdomain interferes with tissue polarity and NFkB activation and permitsapoptosis. These results indicate that integrin-induced polarity maydrive tumor cell resistance to apoptosis-inducing agents via effects onNFkB.

  2. The Cleaning of Aluminum Frame Assembly Units

    SciTech Connect

    Shen, T H

    2001-05-16

    The Brulin immersion and the precision cleaning experiments have shown that neither the Brulin solution nor the precision cleaning in AstroPak causes the smut formation on aluminum surfaces. The acid-bath cleaning in GTC is the primary source of the smut formation. The current GTC acid formulation etches the aluminum matrix quite aggressively, but does not appear to appreciably attack the Si particles. Therefore, this acid-bath cleaning will leave the cast-aluminum part surfaces with many protruded Si particles, which could potentially cause smut problems in the cleaning process down-stream. To ensure the removal of all loose Si particles from the cast-aluminum parts, it is necessary to physically hand-wipe and vigorously wash the acid-bath cleaned surfaces. Furthermore, the casting porosity in alloy A356 could be another source in causing high swipe readings in the FAU parts.

  3. Aluminum, copper, iron and zinc differentially alter amyloid-Aβ(1-42) aggregation and toxicity.

    PubMed

    Bolognin, Silvia; Messori, Luigi; Drago, Denise; Gabbiani, Chiara; Cendron, Laura; Zatta, Paolo

    2011-06-01

    Amyloid-β(1-42) (Aβ) is believed to play a crucial role in the ethiopathogenesis of Alzheimer's Disease (AD). In particular, its interactions with biologically relevant metal ions may lead to the formation of highly neurotoxic complexes. Here we describe the species that are formed upon reacting Aβ with several biometals, namely copper, zinc, iron, and with non-physiological aluminum to assess whether different metal ions are able to differently drive Aβ aggregation. The nature of the resulting Aβ-metal complexes and of the respective aggregates was ascertained through a number of biophysical techniques, including electrospray ionization mass spectrometry, dynamic light scattering, fluorescence, transmission electron microscopy and by the use of conformation-sensitive antibodies (OC, αAPF). Metal binding to Aβ is shown to confer highly different chemical properties to the resulting complexes; accordingly, their overall aggregation behaviour was deeply modified. Both aluminum(III) and iron(III) ions were found to induce peculiar aggregation properties, ultimately leading to the formation of annular protofibrils and of fibrillar oligomers. Notably, only Aβ-aluminum was characterized by the presence of a relevant percentage of aggregates with a mean radius slightly smaller than 30 nm. In contrast, both zinc(II) and copper(II) ions completely prevented the formation of soluble fibrillary aggregates. The biological effects of the various Aβ-metal complexes were studied in neuroblastoma cell cultures: Aβ-aluminum turned out to be the only species capable of triggering amyloid precursor and tau181 protein overproduction. Our results point out that Al can effectively interact with Aβ, forming "structured" aggregates with peculiar biophysical properties which are associated with a high neurotoxicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Effects of Ca(OH)2 assisted aluminum sulfate coagulation on the removal of humic acid and the formation potentials of tri-halomethanes and haloacetic acids in chlorination.

    PubMed

    Duan, Jinming; Cao, Xiaoting; Chen, Cheng; Shi, Dongrui; Li, Genmao; Mulcahy, Dennis

    2012-01-01

    The effects of addition of calcium hydroxide on aluminum sulphate (or alum) coagulation for removal of natural organic matter (NOM) and its subsequent effect on the formation potentials of two major types of regulated disinfection byproducts (DBPs), haloacetic acids (HAAs) and trihalomethanes (THMs), have been examined. The results revealed several noteworthy phenomena. At the optimal coagulation pH (i.e. 6), the coagulation behavior of NOM water solutions versus alum dose, showed large variation and a consequent great change in the formation potentials of the DBPs at certain coagulant doses. However, with addition of a relatively small amount of Ca(OH)2, although the zeta potential of coagulated flocs remained almost the same, NOM removal became more consistent with alum dose. Importantly, also the detrimental effect of charge reversal on NOM removal at the low coagulant dose disappeared. This resulted in a steady decrease in the formation potentials of DBPs as a function of the coagulant dose. Moreover, the addition of Ca(OH)2 broadened the pH range of alum coagulation and promoted further reduction of the formation potentials of the DBPs. The enhancement effects of Ca(OH)2 assisted alum coagulation are especially pronounced at pH 7 and 8. Finally, synchronous fluorescence spectra showed that the reduction in DBPs formation potential by Ca(OH)2-assisted alum coagulation was connected to an enhanced removal of small hydrophobic and hydrophilic HA molecules. Ca(OH)2-assistance of alum coagulation appeared to increase substantially the removal of the hydrophilic HA fraction responsible for HAAs formation, prompting further reduction of HAA formation potentials.

  5. Conference Planning.

    ERIC Educational Resources Information Center

    Burke, W. Warner, Ed.; Beckhard, Richard, Ed.

    This book, written to instruct in the use of a conference as a medium of social intercourse, is divided into four sections. Section I, which contains five articles, deals with factors to be considered in planning a conference. Specific techniques one can employ to improve a conference and several different techniques for evaluating the…

  6. Corrosion of aluminum and aluminum alloys

    SciTech Connect

    Davis, J.R.

    1999-01-01

    This new handbook presents comprehensive coverage of the corrosion behavior of aluminum and aluminum alloys, with emphasis on practical information about how to select and process these materials in order to prevent corrosion attack. Described are the characteristics of these materials and the influences of composition, mechanical working, heat treatment, joining methods, microstructure, and environmental variables on their corrosion.

  7. Aluminum extraction from aluminum industrial wastes

    NASA Astrophysics Data System (ADS)

    Amer, A. M.

    2010-05-01

    Aluminum dross tailings, an industrial waste from the Egyptian Aluminum Company (Egyptalum), was used to produce two types of alums: aluminum sulfate alum (Al2(SO4)3·12H2O) and ammonium aluminum alum {(NH4)2SO4AL2 (SO4)3·24H2O}. This was carried out in two processes. The first involves leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of aluminum sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purified aluminum dross tailings thus produced. This was carried out in an autoclave. The effects of temperature, time of reaction, and acid concentration on pressure leaching and extraction processes were studied in order to specify the optimum conditions to be applied in the bench scale production as well as the kinetics of leaching process.

  8. ALUMINUM-CONTAINING POLYMERS

    DTIC Science & Technology

    ALUMINUM COMPOUNDS, *ORGANOMETALLIC COMPOUNDS, *POLYMERIZATION, *POLYMERS, ACRYLIC RESINS, ALKYL RADICALS, CARBOXYLIC ACIDS, COPOLYMERIZATION, LIGHT TRANSMISSION, STABILITY, STYRENES, TRANSPARENT PANELS.

  9. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  10. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  11. Al-Cd Alloy Formation by Aluminum Underpotential Deposition from AlCl3+NaCl Melts on Cadmium Substrate

    NASA Astrophysics Data System (ADS)

    Jovićević, Niko; Cvetković, Vesna S.; Kamberović, Željko J.; Jovićević, Jovan N.

    2013-02-01

    Aluminum was incorporated into a polycrystalline cadmium electrode surface by underpotential deposition from equimolar AlCl3+ NaCl melt at 473 K, 523 K, and 573 K (200 °C, 250 °C, and 300 °C). The process was studied by linear sweep voltammetry and potentiostatic deposition/galvanostatic striping. The deposits were characterized X-ray diffraction (XRD), Auger electron spectroscopy (AES), and electron probe microanalyzer (EPMA). The electrochemical measurements showed evidence of Cd-Al alloys being formed but they could not be identified. The growth kinetics of the Cd-Al layers of various proportion and depths that depended on temperature and deposition time were described.

  12. Issues for conversion coating of aluminum alloys with hydrotalcite

    SciTech Connect

    Drewien, C.A.; Buchheit, R.G.

    1993-12-01

    Hydrotalcite coatings on aluminum alloys are being developed for corrosion protection of aluminum in aggressive saline environments. Coating bath composition, surface pretreatment, and alloying elements in aluminum all influence the performance of these coatings during salt spray testing. The coating bath, comprised of lithium carbonate, requires aging by dissolution of aluminum into the bath in order to grow corrosion resistant coatings. Coatings formed in non- aged baths do not perform well in salt spray testing. The alloying elements in aluminum alloys, especially copper, influence the coating growth and formation leading to thin coatings. The effect of the alloy elements is to limit the supply of aluminum to the coating/electrolyte interface and hinder growth of hydrotalcite upon aluminum alloys.

  13. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-01-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  14. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet

    NASA Astrophysics Data System (ADS)

    Tadgell, Colin A.; Wells, Mary A.; Corbin, Stephen F.; Colley, Leo; Cheadle, Brian; Winkler, Sooky

    2017-03-01

    The influence of an anodic oxide surface film on the nickel-aluminum reaction at the surface of aluminum brazing sheet has been investigated. Samples were anodized in a barrier-type solution and subsequently sputtered with nickel. Differential scanning calorimetry (DSC) and metallography were used as the main investigative techniques. The thickness of the anodic film was found to control the reaction between the aluminum substrate and nickel coating. Solid-state formation of nickel-aluminum intermetallic phases occurred readily when a relatively thin oxide film (13 to 25 nm) was present, whereas intermetallic formation was suppressed in the presence of thicker oxides ( 60 nm). At an intermediate oxide film thickness of 35 nm, the Al3Ni phase formed shortly after the initiation of melting in the aluminum substrate. Analysis of DSC traces showed that formation of nickel-aluminum intermetallic phases changed the melting characteristics of the aluminum substrate, and that the extent of this change can be used as an indirect measure of the amount of nickel incorporated into the intermetallic phases.

  15. Aluminum reference electrode

    DOEpatents

    Sadoway, D.R.

    1988-08-16

    A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

  16. Aluminum reference electrode

    DOEpatents

    Sadoway, Donald R.

    1988-01-01

    A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

  17. Formation of biphenyl and dibenzofuran phytoalexins in the transition zones of fire blight-infected stems of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference'.

    PubMed

    Chizzali, Cornelia; Khalil, Mohammed N A; Beuerle, Till; Schuehly, Wolfgang; Richter, Klaus; Flachowsky, Henryk; Peil, Andreas; Hanke, Magda-Viola; Liu, Benye; Beerhues, Ludger

    2012-05-01

    In the rosaceous subtribe Pyrinae (formerly subfamily Maloideae), pathogen attack leads to formation of biphenyls and dibenzofurans. Accumulation of these phytoalexins was studied in greenhouse-grown grafted shoots of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference' after inoculation with the fire blight bacterium, Erwinia amylovora. No phytoalexins were found in leaves. However, both classes of defence compounds were detected in the transition zone of stems. The flanking stem segments above and below this zone, which were necrotic and healthy, respectively, were devoid of detectable phytoalexins. The transition zone of apple stems contained the biphenyls 3-hydroxy-5-methoxyaucuparin, aucuparin, noraucuparin and 2'-hydroxyaucuparin and the dibenzofurans eriobofuran and noreriobofuran. In pear, aucuparin, 2'-hydroxyaucuparin, noreriobofuran and in addition 3,4,5-trimethoxybiphenyl were detected. The total phytoalexin content in the transition zone of pear was 25 times lower than that in apple. Leaves and stems of mock-inoculated apple and pear shoots lacked phytoalexins. A number of biphenyls and dibenzofurans were tested for their in vitro antibacterial activity against some Erwinia amylovora strains. The most efficient compound was 3,5-dihydroxybiphenyl (MIC=115 μg/ml), the immediate product of biphenyl synthase which initiates phytoalexin biosynthesis.

  18. Superior Root Hair Formation Confers Root Efficiency in Some, But Not All, Rice Genotypes upon P Deficiency

    PubMed Central

    Nestler, Josefine; Wissuwa, Matthias

    2016-01-01

    Root hairs are a low-cost way to extend root surface area (RSA), water and nutrient acquisition. This study investigated to what extend variation exists for root hair formation in rice in dependence of genotype, phosphorus (P) supply, growth medium, and root type. In general, genotypic variation was found for three root hair properties: root hair length, density, and longevity. In low P nutrient solution more than twofold genotypic difference was detected for root hair length while only onefold variation was found in low P soil. These differences were mostly due to the ability of some genotypes to increase root hair length in response to P deficiency. In addition, we were able to show that a higher proportion of root hairs remain viable even in mature, field-grown plants under low P conditions. All investigated root hair parameters exhibited high correlations across root types which were always higher in the low P conditions compared to the high P controls. Therefore we hypothesize that a low P response leads to a systemic signal in the entire root system. The genotype DJ123 consistently had the longest root hairs under low P conditions and we estimated that, across the field-grown root system, root hairs increased the total RSA by 31% in this genotype. This would explain why DJ123 is considered to be very root efficient in P uptake and suggests that DJ123 should be utilized as a donor in breeding for enhanced P uptake. Surprisingly, another root and P efficient genotype seemed not to rely on root hair growth upon P deficiency and therefore must contain different methods of low P adaptation. Genotypic ranking of root hair properties did change substantially with growth condition highlighting the need to phenotype plants in soil-based conditions or at least to validate results obtained in solution-based growth conditions. PMID:28066487

  19. The Effect of Thermomechanical Processing on Mechanical Properties of a Cast 6061 Aluminum Metal Matrix Composite

    DTIC Science & Technology

    1993-12-01

    Conference Proceedings, 1990 19. Lewandowski, J. J. et al., "Effects of Casting Conditions and Deformation Processing on A356 Aluminum and A356 -20 Vol...CAST 6061 ALUMINUM METAL MATRIX COMPOSITE by Werner Fletcher Hoyt December 1993 Thesis Advisor: Terry R. McNelley Approved for public release...Security Classification) THE EFFECT OF THERMOMECHANICAL PROCESSING ON MECHANICAL PROPERTIES OF A CAST 6061 ALUMINUM METAL MATRIX COMPOSITE 12. PERSONAL

  20. Conference Connections: Rewiring the Circuit

    ERIC Educational Resources Information Center

    Siemens, George; Tittenberger, Peter; Anderson, Terry

    2008-01-01

    Increased openness, two-way dialogue, and blurred distinctions between experts and amateurs have combined with numerous technology tools for dialogue, personal expression, networking, and community formation to "remake" conferences, influencing not only how attendees participate in but also how organizers host conferences today. (Contains 31…

  1. Conference Connections: Rewiring the Circuit

    ERIC Educational Resources Information Center

    Siemens, George; Tittenberger, Peter; Anderson, Terry

    2008-01-01

    Increased openness, two-way dialogue, and blurred distinctions between experts and amateurs have combined with numerous technology tools for dialogue, personal expression, networking, and community formation to "remake" conferences, influencing not only how attendees participate in but also how organizers host conferences today. (Contains 31…

  2. Fabrication of aluminum based nanomaterials

    NASA Astrophysics Data System (ADS)

    Poirier, Dominique

    2009-11-01

    Structural applications in transportation necessitate materials with high specific strength and stiffness. With its low density, aluminum (Al) is an interesting candidate, but further strengthening would be beneficial. In this work, the benefits and limitations of nanoreinforcements for aluminum strengthening has been assessed through the addition of carbon nanotube (CNTs) and nanometric alumina (n-Al2O3) to an aluminum matrix by powder metallurgy. It has been found that mechanical milling can homogeneously disperse n-Al2O3 in aluminum. Furthermore, mechanical milling offers the advantages of strengthening the aluminum powder through grain refinement, cold working, solid solution and precipitation. However, CNTs are damaged by mechanical milling, and their homogeneous dispersion cannot be achieved with a chemical dispersant. Nanocomposite consolidation has presented several challenges as hot pressing resulted in a lack of bonding, grain growth and the formation of Al4C3 from damaged CNTs. Cold spraying of Al2O3/Al has resulted in a porous coating with decreased hardness. The microhardness and compression properties of an Al2O 3/Al nanocomposite produced by mechanical milling followed by hot pressing were measured. Comparison with modeled values and literature results indicates that higher experimental yield strength obtained with the addition of n-Al 2O3 versus micron size Al2O3 is due to in-situ matrix strengthening. Modeling shows that CNTs offer high potential gains in stiffness due to their high aspect ratio and their high Young modulus. On the other hand, as yield gains associated with the addition of nanoreinforcement are mainly due to matrix strengthening, discontinuous nanocomposites do not benefit from the CNT's exceptional strength. In this case, n-Al 2O3 would be selected over CNTs as it is cheaper and more easily dispersed.

  3. The pro-oxidant activity of aluminum.

    PubMed

    Exley, Christopher

    2004-02-01

    Aluminum, a non-redox-active metal is, nevertheless, a pro-oxidant both in in vitro preparations and in vivo. It facilitates both superoxide- and iron-driven biological oxidation by mechanisms that remain to be resolved. More than 10 years ago Fridovich and colleagues suggested that the facilitation of superoxide-driven biological oxidation by aluminum was due to an interaction between the metal and the superoxide radical anion (Free Radic. Biol. Med. 13: 79-81; 1992). This thesis has been examined herein and it is concluded that much, if not all, of the pro-oxidant activity of aluminum might be explained by the formation of an aluminum superoxide semireduced radical ion.

  4. Cluster model of aluminum dense vapor plasma

    NASA Astrophysics Data System (ADS)

    Khomkin, A. L.; Shumikhin, A. S.

    2009-08-01

    The chemical model of aluminum vapor plasma, that take into account the formation of neutral and charged clusters, is suggested. Caloric and thermal equations of state and composition of plasma were received using the available information about properties of metal clusters. It is shown, that aluminum vapors are clusterized with decrease of temperature and with increase of density. Pressure dependence on internal energy is calculated and comparison with experimental data is made. The important role of aluminum clusters, especially in an initial phase of the metals vapor heating, is demonstrated. It is shown, that the region of plasma clusterization in gaseous phase agree with known literature data for binodal of vapor-liquid transition from gaseous region. Suggested cluster model may be used to forecast the location of metal vapors binodal. The conductivity of aluminum vapor plasma was calculated. The satisfactory agreement with available experimental data is received.

  5. Analysis of hydrolysis process of γ-methacryloxypropyltrimethoxysilane and its influence on the formation of silane coatings on 6063 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Pantoja, M.; Díaz-Benito, B.; Velasco, F.; Abenojar, J.; del Real, J. C.

    2009-04-01

    In this paper the hydrolysis process of γ-methacryloxypropyltrimethoxysilane (MPS) at 1% in an aqueous solution by means of Fourier transform infrared (FTIR) spectroscopy was studied. The aim of this work is to determine the hydrolysis time for which a greater number of Si-OH groups has been obtained. Different hydrolysis times at pH 4 were studied to establish the most optimal application conditions for bonding to the substrate. It was possible to observe how the bands corresponding to the Si-O-C groups present in the pure silane spectrum continued to appear after short periods of hydrolysis. However these bands practically disappeared upon increasing of this hydrolysis time, with other new ones appearing corresponding to the Si-OH vibration. The silanization of 6063 aluminum alloy samples was also carried out. Analysis of the silane layers by means of FTIR indicated that the immersion time may be important according to the hydrolysis conditions, and it also allowed optimizing the drying time.

  6. Aluminum: Recycling of Aluminum Dross/Saltcake

    SciTech Connect

    Blazek, S.

    1999-01-29

    As this NICE3 publication details, the objective of this project is to commercialize the process technology to eliminate all landfill waste associated with black dross and saltcake generated from aluminum recycling in the United States.

  7. The viability of aluminum Zintl anion moieties within magnesium-aluminum clusters

    SciTech Connect

    Wang, Haopeng; Jae Ko, Yeon; Zhang, Xinxing; Gantefoer, Gerd; Bowen, Kit H. E-mail: akandalam@wcupa.edu; Schnoeckel, Hansgeorg; Eichhorn, Bryan W.; Jena, Puru; Kiran, Boggavarapu E-mail: akandalam@wcupa.edu; Kandalam, Anil K. E-mail: akandalam@wcupa.edu

    2014-03-28

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have investigated the extent to which the aluminum moieties within selected magnesium-aluminum clusters are Zintl anions. Magnesium-aluminum cluster anions were generated in a pulsed arc discharge source. After mass selection, photoelectron spectra of Mg{sub m}Al{sub n}{sup −} (m, n = 1,6; 2,5; 2,12; and 3,11) were measured by a magnetic bottle, electron energy analyzer. Calculations on these four stoichiometries provided geometric structures and full charge analyses for the cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra). Calculations revealed that, unlike the cases of recently reported sodium-aluminum clusters, the formation of aluminum Zintl anion moieties within magnesium-aluminum clusters was limited in most cases by weak charge transfer between the magnesium atoms and their aluminum cluster moieties. Only in cases of high magnesium content, e.g., in Mg{sub 3}Al{sub 11} and Mg{sub 2}Al{sub 12}{sup −}, did the aluminum moieties exhibit Zintl anion-like characteristics.

  8. International Conference on Human Relations.

    DTIC Science & Technology

    2007-11-02

    Festinger , Sherif, Ex, Rohrer, Pinto, Singh, and Mailhiot. One outcome of the Conference was the formation of a working committee to establish an International Documentation and Information Center for the field of Human Relations.

  9. Making Conferences Human Places of Learning

    ERIC Educational Resources Information Center

    Kenny, Michael

    2014-01-01

    Open Space Technology is a cumbersome name for a participative conference model that enables dynamic inclusive engagement and challenges traditional, highly structured hierarchical conference formats. Based on self-organising systems, (Wenger, 1998) Open Space Technology conferences have an open process, start with no agenda and empower the most…

  10. A Model for Replication: Conference for Parents.

    ERIC Educational Resources Information Center

    Meriweather, Suzanne; Karnes, Frances A.

    1988-01-01

    The experience of the University of Southern Mississippi in sponsoring "The Parenting the Gifted Children Conference" is described. Discussed are needs assessment, conference format, selection of speakers, budget, public relations, conference evaluation, and physical facilities. Included are a sample evaluation form, a conference…

  11. Aspects of aluminum toxicity

    SciTech Connect

    Hewitt, C.D.; Savory, J.; Wills, M.R. )

    1990-06-01

    Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

  12. The formation of tungsten doped Al2O3/ZnO coatings on aluminum by plasma electrolytic oxidation and their application in photocatalysis

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Vasilić, Rastko; Radić, Nenad; Tadić, Nenad; Stefanov, Plamen; Grbić, Boško

    2016-07-01

    Tungsten doped Al2O3/ZnO coatings are formed by plasma electrolytic oxidation of aluminum substrate in supporting electrolyte (0.1 M boric acid + 0.05 M borax + 2 g/L ZnO) with addition of different concentrations of Na2WO4·2H2O. The morphology, crystal structure, chemical composition, and light absorption characteristics of formed surface coatings are investigated. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that formed surface coatings consist of alpha and gamma phase of Al2O3, ZnO, metallic tungsten and WO3. Obtained results showed that incorporated tungsten does not have any influence on the absorption spectra of Al2O3/ZnO coatings, which showed invariable band edge at about 385 nm. The photocatalytic activity of undoped and tungsten doped Al2O3/ZnO coatings is estimated by the photodegradation of methyl orange. The photocatalytic activity of tungsten doped Al2O3/ZnO coatings is higher thanof undoped Al2O3/ZnO coatings; the best photocatalytic activity is ascribed to coatings formed in supporting electrolyte with addition of 0.3 g/L Na2WO4·2H2O. Tungsten in Al2O3/ZnO coatings acts as a charge trap, thus reducing the recombination rate of photogenerated electron-hole pairs. The results of PL measurements are in agreement with photocatalytic activity. Declining PL intensity corresponds to increasing photocatalytic activity of the coatings, indicating slower recombination of electron-hole pairs.

  13. Spot welding of steel and aluminum using insert sheet

    SciTech Connect

    Oikawa, H.; Saito, T.; Yoshimura, T.

    1994-12-31

    Automobile industries have been increasingly interested in the use of aluminum and thus joining of steel and aluminum becomes of importance. The joining of the two types of metal raises a problem of brittle welds caused by the formation of intermetallic compounds. The authors solved the problem by using an insert sheet. This paper deals with the resistance spot welding of steel and aluminum sheets using insert sheets. The insert sheet used in the present development was a steel/aluminum clad sheet of the 0.8 mm thickness with 50% steel and 50% aluminum. The clad sheet was produced by warm rolling of steel and aluminum with a direct resistance heating process. Steel to be warm rolled was of EDDQ of the 0.4 mm thickness and aluminum was of JIS A1050 of 0.6 mm thickness. The mechanical properties of the insert clad sheets were in between those of the steel sheets and the aluminum sheets, while the clad sheets showed much better formability than the aluminum sheets. Resistance spot welding was conducted for 0.8 mm thick EDDQ steel sheets and 1.0 mm thick aluminum alloy (AL-5.5%Mg) sheets under the welding force of 1.96 kN, welding current ranging between 4.2 and 20.1 kA, and welding time from 0.5 to 10 cycles. The steel was spot welded to the steel side of the insert sheet while the aluminum was welded to the aluminum side. What the authors investigated were the applicable welding current range, nugget diameter, tensile shear strength, U-tension strength, and macro- and microstructures. In conclusion, steel sheets can be spot welded to aluminum sheets without difficulty by using clad sheets as insert materials while the strength level of the dissimilar metal spot welds is close to that of aluminum joints.

  14. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  15. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  16. Aluminum Cartridge Case Concept

    DTIC Science & Technology

    2005-05-01

    carried by the soldier, a lightweight alternative to the brass cartridge case is an aluminum cartridge case. This comprehensive detailed report describes...AD AD-E403 044 Technical Report ARAEW-TR-05003 ALUMINUM CARTRIDGE CASE CONCEPT Brian Tasson ATK Ordnance and Ground Systems LLC 4700 Nathan Lane...TITLE AND SUBTITLE 5a. CONTRACT NUMBER DAAE30-03-C-1 128 ALUMINUM CARTRIDGE CASE CONCEPT 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHORS 5d

  17. Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

    Treesearch

    K. Heckman; A.S. Grandy; X. Gao; M. Keiluweit; K. Wickings; K. Carpenter; J. Chorover; C. Rasmussen

    2013-01-01

    Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering...

  18. Deposition behavior of residual aluminum in drinking water distribution system: Effect of aluminum speciation.

    PubMed

    Zhang, Yue; Shi, Baoyou; Zhao, Yuanyuan; Yan, Mingquan; Lytle, Darren A; Wang, Dongsheng

    2016-04-01

    Finished drinking water usually contains some residual aluminum. The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps. A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride (PACl). In this work, the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test, batch reactor test and quartz crystal microbalance with dissipation monitoring. The deposition amount of non-polymeric aluminum species was the least, and its deposition layer was soft and hydrated, which indicated the possible formation of amorphous Al(OH)3. Al13 had the highest deposition tendency, and the deposition layer was rigid and much less hydrated, which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al13 could be the main deposition mechanism. While for Al30, its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al13. However, the total deposited mass of Al30 was much higher than that of Al13, which was attributed to the deposition of particulate aluminum matters with much higher hydration state. Compared with stationary condition, stirring could significantly enhance the deposition process, while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.

  19. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F.

    2002-11-05

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  20. Combined surface modification of commercial aluminum

    NASA Astrophysics Data System (ADS)

    Ivanov, Yu; Lopatin, I.; Akhmadeev, Yu; Petrikova, E.; Teresov, A.; Shugurov, V.; Tolkachev, O.; Koval, N.

    2017-01-01

    The paper analyzes research data on the structure and properties of surface layers of commercially pure A7-grade aluminum subjected to treatment that combines deposition of a thin metal film, intense pulsed electron beam irradiation, and nitriding in low-pressure arc plasma. The analysis shows that the combined method of surface modification provides the formation of a multilayer structure with submicro- and nano-sized phases in the material through a depth of up to 40 μm, allowing a manifold increase in its surface microhardness and wear resistance (up to 4 and 9 times, respectively) compared to the material core. The main factors responsible for the high surface strength are the saturation of the aluminum lattice with nitrogen atoms and the formation of nano-sized particles of aluminum nitride and iron aluminides.

  1. Closing the Loop: An interactive action-research conference format for delivering updated medical information while eliciting Latina patient/family experiences and psychosocial needs post-genetic cancer risk assessment

    PubMed Central

    MacDonald, Deborah J.; Deri, Julia; Ricker, Charité; Perez, Martin A.; Ogaz, Raquel; Feldman, Nancy; Viveros, Lori A.; Paz, Benjamin; Weitzel, Jeffrey N.; Blazer, Kathleen R.

    2013-01-01

    Objective A patient/family-centered conference was conducted at an underserved community hospital to address Latinas’ post-genetic cancer risk assessment (GCRA) medical information and psychosocial support needs, and determine the utility of the action research format. Methods Latinas seen for GCRA were recruited to a half-day conference conducted in Spanish. Content was partly determined from follow-up survey feedback. Written surveys, interactive discussions, and Audience Response System (ARS) queries facilitated the participant-healthcare professional action research process. Analyses included descriptive statistics and thematic analysis. Results The 71 attendees (41 patients and 27 relatives/friends) were primarily non-U.S. born Spanish-speaking females, mean age 43 years. Among patients, 73% had a breast cancer history; 85% had BRCA testing (49% BRCA+). Nearly all (96%) attendees completed the conference surveys and ARS queries; ≥48% participated in interactive discussions. Most (95%) agreed that the format met their personal interests and expectations and provided useful information and resources. Gaps/challenges identified in the GCRA process included pre-consult anxiety, uncertainty about reason for referral and expected outcomes, and psychosocial needs post-GCRA, such as absorbing and disseminating risk information to relatives and concurrently coping with a recent cancer diagnosis. Conclusions The combined action research and educational conference format was innovative and effective for responding to continued patient information needs and addressing an important data gap about support needs of Latina patients and family members following genetic cancer risk assessment. Findings informed GCRA process improvements and provide a basis for theory-driven cancer control research. PMID:22678665

  2. High energy density aluminum battery

    DOEpatents

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  3. 3D finite element prediction of chip flow, burr formation, and cutting forces in micro end-milling of aluminum 6061-T6

    NASA Astrophysics Data System (ADS)

    Davoudinejad, A.; Parenti, P.; Annoni, M.

    2017-06-01

    Predictive models for machining operations have been significantly improved through numerous methods in recent decades. This study proposed a 3D finite element modeling (3D FEM) approach for the micro end-milling of Al6061-T6. Finite element (FE) simulations were performed under different cutting conditions to obtain realistic numerical predictions of chip flow, burr formation, and cutting forces. FE modeling displayed notable advantages, such as capability to easily handle any type of tool geometry and any side effect on chip formation, including thermal aspect and material property changes. The proposed 3D FE model considers the effects of mill helix angle and cutting edge radius on the chip. The prediction capability of the FE model was validated by comparing numerical model and experimental test results. Burr dimension trends were correlated with force profile shapes. However, the FE predictions overestimated the real force magnitude. This overestimation indicates that the model requires further development.

  4. Microbial corrosion of aluminum alloy.

    PubMed

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors.

  5. Is the Aluminum Hypothesis Dead?

    PubMed Central

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  6. Is the Aluminum Hypothesis dead?

    PubMed

    Lidsky, Theodore I

    2014-05-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust.

  7. Aluminum: Reducing chloride emissions from aluminum production

    SciTech Connect

    Simon, P.

    1999-09-29

    Reynolds Metals Company (RMC), with assistance from a NICE{sup 3} grant, is developing for commercialization a closed-loop control process that greatly reduces chlorine emissions and increases plant efficiency while maintaining metal quality. The process still utilizes chlorine to remove impurities during aluminum processing, but is more effective than current methods. With the new technology chlorine in the stack is monitored and input chlorine is adjusted continuously. This optimization of chlorine use results in substantially less waste because less chlorine has to be bought or produced by aluminum manufacturers. This innovation is a significant improvement over conventional aluminum treatments, in which chlorine is injected in a more costly and wasteful manner. By the year 2010, the new technology has the potential to reduce the energy it takes to create chlorine by 8.4 billion Btu per year and to cut greenhouse gas emissions by 1,377 tons per year.

  8. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  9. Aluminum space frame technology

    SciTech Connect

    Birch, S.

    1994-01-01

    This article examines the increased application of aluminum to the construction of automobile frames. The topics of the article include a joint venture between Audi and Alcoa, forms in which aluminum is used, new alloys and construction methods, meeting rigidity and safety levels, manufacturing techniques, the use of extrusions, die casting, joining techniques, and pollution control during manufacturing.

  10. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are…

  11. Aluminum structural applications

    SciTech Connect

    Lucas, G.

    1996-05-01

    Extensive research by aluminum producers and automakers in the 1980s resulted in the development of technologies that enable building of aluminum cars that meet and exceed all the expectations of today`s drivers and passengers, yet weigh several hundred pounds less than their steel counterparts. The Acura NSX sports car, the Audi A8, and the Jaguar XJ220 have all been introduced. Ford has built 40 aluminum-intensive automobiles based on the Taurus/Sable for test purposes, and General Motors recently announced an aluminum-structured electric vehicle. The design flexibility that aluminum allows is shown by these examples. Each uses a somewhat different technology that is particularly suited to the vehicle and its market.

  12. The Aluminum Smelting Process

    PubMed Central

    2014-01-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  13. Regeneration of Aluminum Hydride studied with Raman Microscopy.

    NASA Astrophysics Data System (ADS)

    Lacina, David; Graetz, Jason; Reilly, J. J.

    2009-03-01

    We are interested in developing new methods to form aluminum hydride directly from aluminum powder and hydrogen. Due to the low free energy of formation, aluminum and hydrogen require extremely high pressures to react and form the hydride. It is possible to form alane directly at low pressure when it is catalyzed with a small amount of titanium (2 mol %) and stabilized as an adduct. We have studied the formation of amine-alanes by direct hydrogenation of aluminum and have attempted to understand the mechanisms behind these reversible reactions and the role of the catalyst. We will present the results from our recent survey of possible reactions between aluminum, hydrogen and various amines. We will also present the results of a Raman spectroscopy study of the alane polymorphs at ambient and high pressure and alane amines.

  14. Managing aluminum phosphide poisonings.

    PubMed

    Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

    2011-07-01

    Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO(4), coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management.

  15. Managing aluminum phosphide poisonings

    PubMed Central

    Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

    2011-01-01

    Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO4, coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management. PMID:21887030

  16. Paint-Bonding Improvement for 2219 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Daech, Alfred F.; Cibula, Audrey Y.

    1987-01-01

    Bonding of adhesives and primers to 2219 aluminum alloy improved by delaying rinse step in surface-treatment process. Delaying rinse allows formation of rougher surface for stronger bonding and greater oxide buildup.

  17. Biomedical Conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

    As a result of Biomedical Conferences, Vivo Metric Systems Co. has produced cardiac electrodes based on NASA technology. Frequently in science, one highly specialized discipline is unaware of relevant advances made in other areas. In an attempt to familiarize researchers in a variety of disciplines with medical problems and needs, NASA has sponsored conferences that bring together university scientists, practicing physicians and manufacturers of medical instruments.

  18. Interdisciplinary Quality Improvement Conference: Using a Revised Morbidity and Mortality Format to Focus on Systems-Based Patient Safety Issues in a VA Hospital: Design and Outcomes.

    PubMed

    Gerstein, Wendy H; Ledford, Judith; Cooper, Jacqueline; Lloyd, Melissa G; Moore, Timothy; Harji, Farzana; Twitty, Vivian; Brooks, Annette; Oliver, Rosalinda C; Goff, James M

    2016-01-01

    The Veterans Healthcare Administration (VA) has embraced patient safety and quality improvement in the quest to improve care for veterans. The New Mexico VA Health Care System introduced a new morbidity and mortality conference, called the Interdisciplinary Quality Improvement Conference (IQIC), using patient case presentations to focus on underlying systems in the clinical care environment. The revised conference design also effectively teaches the 6 Accreditation Council for Graduate Medical Education (ACGME) core requirements for resident education. A formal process was established for case selection, presentation, systems issue identification, tracking, and follow-up. The IQIC has enabled the identification of more than 20 system issues at the study institution. Outcome data show lasting improvement in system issues that were addressed by this mechanism. The VA IQIC is an effective method to both identify and correct systems issues that affect patient care and is an effective method for teaching residents the 6 ACGME requirements for residency education. © The Author(s) 2014.

  19. Clinical biochemistry of aluminum

    SciTech Connect

    King, S.W.; Savory, J.; Wills, M.R.

    1981-05-01

    Aluminum toxicity has been implicated in the pathogenesis of a number of clinical disorders in patients with chronic renal failure on long-term intermittent hemodialysis treatment. The predominant disorders have been those involving either bone (osteomalacic dialysis osteodystrophy) or brain (dialysis encephalopathy). In nonuremic patients, an increased brain aluminum concentration has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer's disease and was associated with experimental neurofibrillary degeneration in animals. The brain aluminum concentrations of patients dying with the syndrome of dialysis encephalopathy (dialysis dementia) are significantly higher than in dialyzed patients without the syndrome and in nondialyzed patients. Two potential sources for the increased tissue content of aluminum in patients on hemodialysis have been proposed: (1) intestinal absorption from aluminum containing phosphate-binding gels, and (2) transfer across the dialysis membrane from aluminum in the water used to prepare the dialysate. These findings, coupled with our everyday exposure to the ubiquitous occurrence of aluminum in nature, have created concerns over the potential toxicity of this metal.

  20. Purifying Aluminum by Vacuum Distillation

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1985-01-01

    Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

  1. Purifying Aluminum by Vacuum Distillation

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1985-01-01

    Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

  2. Cast Aluminum Bonding Study

    DTIC Science & Technology

    1988-05-01

    fabricated using P?-’r;est11 bur)ld II19 te(hnll I Oly with 6 cIsL nqs. The cast a lumi num alloy used was A357 . The sur- face preparation was phosphoric acid...from a cast aluminum alloy designated A357 . The bonding surfaces of the adherends were prepared using PAA. One primer and two adhesives considered...System, Cast Aluminum Lap Shear 18 11 Bond Area of 350°F Adhesive System, Cast Aluminum Lap Shear 19 vi LIST OF TABLES TABLE PAGE 1 A357 Chemical

  3. Aluminum Nitride Crystal Growth

    DTIC Science & Technology

    1979-12-01

    UOSR-TR- 80 - 04 2 4EL4- G LEYEL ALUMINUM NITRIDE CRYSTAL GROWTH G.A. Slack FINAL REPORT Contract F49620-78-C-0021 DTIC Period Covered ELECTE I...Laboratory personnel worked on the problem of Aluminum Nitride Heat Sink Crystal Growth for the U.S. Air Force Office of Scientific Research under Contract...Number F44620-76-C-0039. From November 1, 1977 to the present we have worked on Aluminum Nitride and Boron Phosphide Crystal Growth under Contract NUmber

  4. Walnut Hulls Clean Aluminum

    NASA Technical Reports Server (NTRS)

    Colberg, W. R.; Gordon, G. H.; Jackson, C. H.

    1984-01-01

    Hulls inflict minimal substrate damage. Walnut hulls found to be best abrasive for cleaning aluminum surfaces prior to painting. Samples blasted with walnut hulls showed no compressive stress of surface.

  5. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  6. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  7. A Study on Formation and Thermal Stability of Nano-sized Oxide Clusters in Mechanically Alloyed Nickel Aluminum for High Temperature Applications

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Deog

    the thermal stability during an extensive matrix of long-term thermal annealing. In particular, the size, number density and composition of nano-clusters were assessed. While improvements in strength were obtained in the advanced NiAl ODS alloys, and the higher strength persisted through thermal annealing for 100 hrs at 1723K, characterization revealed the presence of Al in the oxide precipitate phases. The Al incorporation is believed detrimental to the formation of a high density of thermally stable Y-Ti-O nanoscale precipitates.

  8. CORROSION PROTECTION OF ALUMINUM

    DOEpatents

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  9. Corrosion Protection of Aluminum

    DOEpatents

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  10. Aluminum powder applications

    SciTech Connect

    Gurganus, T.B.

    1995-08-01

    Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the key to some of the most exciting new developments in the aluminum future.

  11. Graphene tunnel junctions with aluminum oxide barrier

    NASA Astrophysics Data System (ADS)

    Feng, Ying; Trainer, Daniel J.; Chen, Ke

    2016-10-01

    We report a development of graphene tunnel junctions made by chemical vapor deposition grown graphene and sputtered aluminum insulating by an in-situ grown aluminum oxide. The thin oxide layer formed in between the metal layer and the two-dimensional material is a crucial part of a tunnel junction. We characterized surface morphology of oxide layers and studied tunneling spectra of lead and silver tunnel junctions to estimate the quality of the aluminum oxide. The Brinkman-Rowell-Dynes model was applied to fit the conductance-voltage plots to calculate the thickness of oxide layers. Junctions with graphene both on bottom and on top were fabricated and their tunneling properties were characterized after exposure to air for weeks to test time stability. Furthermore, the resistances of graphene tunnel junctions with aluminum oxide formed naturally and in an oxygen atmosphere were studied. Our results demonstrate that in-situ aluminum oxide is an effective barrier for graphene tunnel junctions. The methods of barrier formation enable the realization of more tunnel devices and circuits based on graphene.

  12. Conference reports

    NASA Astrophysics Data System (ADS)

    Dongpei, Chen; Yulong, Ma

    1994-12-01

    The Ultrasonic Electronics Branch Society of the China Acoustics Society, and the Electronics Countermeasure Branch Society of the China Electronics Society held and All-China Applications Conference of Ultrasonic Electronics Devices in Electronic Countermeasures, Radar and Military Communication Technology. A total of 66 papers was received by the conference with contents relating to surface acoustic wave devices, high-frequency acoustic wave devices, acousto-optical devices, applications of devices in radar, applications of devices in electronic countermeasures, and applications of devices in military communication systems.

  13. Formation of multinary intermetallics from reduction of perovskites by aluminum flux: M(3)Au(6+)(x)()Al(26)Ti (M = Ca, Sr, Yb), a stuffed variant of the BaHg(11) type.

    PubMed

    Latturner, Susan E; Kanatzidis, Mercouri G

    2004-01-12

    New intermetallic phases were synthesized by reacting oxidic perovskites and gold metal in aluminum flux. The combination of MTiO(3) (M = Ca, Sr, Ba) and Au metal in excess molten aluminum produces quaternary compounds M(3)Au(6+)(x)()Al(26)Ti with a stuffed BaHg(11) structure type. An analogue with M = Yb was also synthesized; it shows mixed valent behavior.

  14. Interfacial characterization in carbon nanotube reinforced aluminum matrix composites

    SciTech Connect

    Housaer, F.; Beclin, F.; Touzin, M.; Tingaud, D.; Legris, A.; Addad, A.

    2015-12-15

    In this work, the effects of the sintering parameters, such as temperature and the techniques used (HP and SPS), on CNT/Al composite interfaces are studied. The major role of the native aluminum oxide (Al{sub 2}O{sub 3}) layer covering the aluminum grains is highlighted. It is shown that, for a sintering temperature below 620 °C, the amorphous Al{sub 2}O{sub 3} layer prevents the reaction between aluminum and carbon. For greater sintering temperatures, the breaking of the oxide layer due to its crystallization leads to the formation of aluminum carbide (Al{sub 4}C{sub 3}) by reaction between aluminum and the CNT. The Al{sub 4}C{sub 3} crystals grow perpendicularly to the matrix grain boundaries by thermally activated diffusion of the carbon atoms coming from the CNT. It is also demonstrated that, by limiting the sintering time, which is the case in SPS, it is possible to limit the growth of the Al{sub 4}C{sub 3} crystals and thus to preserve the CNT. - Highlights: • The high reactivity between CNT and Al matrix, resulting Al{sub 4}C{sub 3} formation during the sintering process is highlighted. • We demonstrate, thanks to in-situ TEM observations, that Al{sub 4}C{sub 3} crystals grow into aluminum grains by carbon diffusion. • The native aluminum oxide around the aluminum particles prevents the diffusion of carbon into the aluminum grains. • We show that the protective layer can be broken because of its crystallization, leading to the formation of Al{sub 4}C{sub 3}. • SPS, by limiting the sintering duration, is an interesting way for preparing CNT/Al composites without carbide formation.

  15. Effect of aluminum thickness on solar cell performance

    NASA Astrophysics Data System (ADS)

    Amick, James A.; Bottari, Frank J.; Hanoka, Jack I.

    1994-06-01

    For crystalline silicon solar cells having an alloyed aluminum back contact, open-circuit voltage increases with aluminum thickness. The increase is ascribed to the formation of a p(+)/p 'high-low' junction by liquid-phase epitaxy, resulting in increased efficiency for the cell. With thick aluminum layers, the characteristics of the p(+) regrown region are in reasonable agreement with predictions based on the Al-Si phase diagram. With thin aluminum layers the junction is nonideal, and the improvement in V(sub oc) is much smaller. Pile-up of metallic impurities at the aluminum/p(+) interface is attributed to rejection of these impurities during the silicon regrowth process.

  16. Conference Summary

    ERIC Educational Resources Information Center

    Doherty, Cait

    2009-01-01

    This article summarizes an original conference, organised by the Child Care Research Forum (http://www.qub.ac.uk/sites/ccrf/), which brought together experts from all over Northern Ireland to showcase some of the wealth of research with children and young people that is going on in the country today. Developed around the six high-level outcomes of…

  17. The conference

    Treesearch

    Gordon M. Heisler; Lee P. Herrington

    1977-01-01

    This is a report on the Conference on Metropolitan Physical Environment, held in August 1975 at Syracuse, N.Y., where some 160 scientists and planners met to discuss the use of vegetation, space, and structures to improve the amenities for people who live in metropolitan areas.

  18. Conference Space

    ERIC Educational Resources Information Center

    Tillett, Wade

    2016-01-01

    The following is an exploration of the spatial configurations (and their implications) within a typical panel session at an academic conference. The presenter initially takes up different roles and hyperbolically describes some possible messages that the spatial arrangement sends. Eventually, the presenter engages the audience members in atypical…

  19. Conference Space

    ERIC Educational Resources Information Center

    Tillett, Wade

    2016-01-01

    The following is an exploration of the spatial configurations (and their implications) within a typical panel session at an academic conference. The presenter initially takes up different roles and hyperbolically describes some possible messages that the spatial arrangement sends. Eventually, the presenter engages the audience members in atypical…

  20. Proceedings of the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference (ADC/FCT 2003). Supplement 1

    NASA Technical Reports Server (NTRS)

    Murakawa, M. (Editor); Miyoshi, K. (Editor); Koga, Y. (Editor); Schaefer, L. (Editor); Tzeng, Y. (Editor)

    2003-01-01

    This document contains 2 reports which were presented at the Seventh Applied Diamond Conference/Third Frontier Carbon Technology Joint Conference. The topics discuss the formation of C-N nanofibers as well as the characterization of diamond thin films.

  1. Chemical Reduction Synthesis of Iron Aluminum Powders

    NASA Astrophysics Data System (ADS)

    Zurita-Méndez, N. N.; la Torre, G. Carbajal-De; Ballesteros-Almanza, L.; Villagómez-Galindo, M.; Sánchez-Castillo, A.; Espinosa-Medina, M. A.

    In this study, a chemical reduction synthesis method of iron aluminum (FeAl) nano-dimensional intermetallic powders is described. The process has two stages: a salt reduction and solvent evaporation by a heat treatment at 1100°C. The precursors of the synthesis are ferric chloride, aluminum foil chips, a mix of Toluene/THF in a 75/25 volume relationship, and concentrated hydrochloric acid as initiator of the reaction. The reaction time was 20 days, the product obtained was dried at 60 °C for 2 h and calcined at 400, 800, and 1100 °C for 4 h each. To characterize and confirm the obtained synthesis products, X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques were used. The results of morphology and chemical characterization of nano-dimensional powders obtained showed a formation of agglomerated particles of a size range of approximately 150 nm to 1.0 μm. Composition of powders was identified as corundum (Al2O3), iron aluminide (FeAl3), and iron-aluminum oxides (Fe0. 53Al0. 47)2O3 phases. The oxide phases formation were associated with the reaction of atmospheric concentration-free oxygen during synthesis and sintering steps, reducing the concentration of the iron aluminum phase.

  2. Aluminum, parathyroid hormone, and osteomalacia

    SciTech Connect

    Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.

    1983-01-01

    Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.

  3. Insertion of benzonitrile into Al-N and ga-N bonds: formation of fused carbatriaza-gallanes/alanes and their subsequent synthesis from amidines and trimethyl-gallium/aluminum.

    PubMed

    Maheswari, K; Rao, A Ramakrishna; Reddy, N Dastagiri

    2015-02-16

    Insertion of aromatic nitriles into Al-N and Ga-N bonds are reported. Sterically less hindered aluminum amide [PhNHAlMe2]2 (1) undergoes C≡N insertion with benzonitrile to give an isomeric mixture of tetracyclic triazaalanes {[PhNC(Ph)N]3[PhNC(Ph)NH]Al[AlMe][AlMe2]2} (2 and 3). A similar reaction with analogous gallium amide affords a tetracyclic triazagallane {[PhNC(Ph)N]3[PhNC(Ph)NH]Ga[GaMe][GaMe2]2} (6) along with a novel bowl shaped carbon containing Ga-N cluster {[PhNC(Ph)N][PhN][GaMe]2}3 (5). On the other hand, when sterically bulky gallium amide (Dipp on N, Dipp = 2,6-diisopropylphenyl) is employed, a tetrameric gallium amidinate {[(Dipp)NC(Ph)N]GaMe}4 (8) is obtained. Tetracyclic triazagallazane 6 is also synthesized from the condensation reaction of N-phenylbenzamidine with GaMe3·OEt2. Unlike AlMe3, this reaction produces only one isomer. In case of amidines with bulkier substituents on N such as Dipp, formation of a bicyclic triazagallane {[(Dipp)NC(Ph)NH]2[(Dipp)NC(Ph)N][GaMe]2} (14) is also observed along with tetrameric gallium amidinate 8, whereas N-tert-butylbenzamidine affords exclusively a tetrameric gallium amidinate {[(tert-Bu)NC(Ph)N]GaMe}4 (15) similar to its Al analogue. However, treating N-(Dipp)acetamidine with GaMe3·OEt2 gives only a bicyclic triazagallane {[(Dipp)NC(Me)NH]2[(Dipp)NC(Me)N][GaMe]2} (16). An intermediate [(tert-Bu)N(H) C(Ph)NGaMe2]2 (17), which is involved in the formation of tetrameric gallium amidinate 15, is also characterized. A comparison of the structural parameters of Ga-N-C and Al-N-C frameworks synthesized in this study is reported.

  4. Fatal aluminum phosphide poisoning.

    PubMed

    Anger, F; Paysant, F; Brousse, F; Le Normand, I; Develay, P; Gaillard, Y; Baert, A; Le Gueut, M A; Pepin, G; Anger, J P

    2000-03-01

    A 39-year-old man committed suicide by ingestion of aluminum phosphide, a potent mole pesticide, which was available at the victim's workplace. The judicial authority ordered an autopsy, which ruled out any other cause of death. The victim was discovered 10 days after the ingestion of the pesticide. When aluminum phosphide comes into contact with humidity, it releases large quantities of hydrogen phosphine (PH3), a very toxic gas. Macroscopic examination during the autopsy revealed a very important asphyxia syndrome with major visceral congestion. Blood, urine, liver, kidney, adrenal, and heart samples were analyzed. Phosphine gas was absent in the blood and urine but present in the brain (94 mL/g), the liver (24 mL/g), and the kidneys (41 mL/g). High levels of phosphorus were found in the blood (76.3 mg/L) and liver (8.22 mg/g). Aluminum concentrations were very high in the blood (1.54 mg/L), brain (36 microg/g), and liver (75 microg/g) compared to the usual published values. Microscopic examination revealed congestion of all the organs studied and obvious asphyxia lesions in the pulmonary parenchyma. All these results confirmed a diagnosis of poisoning by aluminum phosphide. This report points out that this type of poisoning is rare and that hydrogen phosphine is very toxic. The phosphorus and aluminum concentrations observed and their distribution in the different viscera are discussed in relation to data in the literature.

  5. First Stars III Conference Summary

    NASA Astrophysics Data System (ADS)

    O'Shea, B. W.; McKee, C. F.; Heger, A.; Abel, T.

    2008-03-01

    The understanding of the formation, life, and death of Population III stars, as well as the impact that these objects had on later generations of structure formation, is one of the foremost issues in modern cosmological research and has been an active area of research during the past several years. We summarize the results presented at "First Stars III," a conference sponsored by Los Alamos National Laboratory, the Kavli Institute for Particle Astrophysics and Cosmology, and the Joint Institute for Nuclear Astrophysics. This conference, the third in a series, took place in July 2007 at the La Fonda Hotel in Santa Fe, New Mexico, U.S.A.

  6. Antibody immobilization on a nanoporous aluminum surface for immunosensor development

    NASA Astrophysics Data System (ADS)

    Chai, Changhoon; Lee, Jooyoung; Park, Jiyong; Takhistov, Paul

    2012-12-01

    A method of antibody (Ab) immobilization on a nanoporous aluminum surface for an electrochemical immunosensor is presented. To achieve good attachment and stability of Ab on an aluminum surface, aluminum was silanized with 3-aminopropyltryethoxysilane (APTES), and then covalently cross-linked to self-assembled layers (SALs) of APTES. Both the APTES concentration and the silanization time affected the formation of APTES-SALs as Ab immobilization. The formation of APTES-SALs was confirmed using the water contact angle on the APTES-SALs surface. The reactivity of APTES-SALs with Ab was investigated by measuring the fluorescence intensity of fluorescein isothiocyanate-labeled Ab-immobilized on the aluminum surface. Silanization of aluminum in 2% APTES for 4 h resulted in higher water contact angles and greater amounts of immobilized Ab than other APTES concentrations or silanization times. More Ab was immobilized on the nanoporous surface than on a planar aluminum surface. Electrochemical immunosensors developed on the nanoporous aluminum via the Ab immobilization method established in this study responded functionally to the antigen concentration in the diagnostic solution.

  7. New Process for Grain Refinement of Aluminum. Final Report

    SciTech Connect

    Dr. Joseph A. Megy

    2000-09-22

    A new method of grain refining aluminum involving in-situ formation of boride nuclei in molten aluminum just prior to casting has been developed in the subject DOE program over the last thirty months by a team consisting of JDC, Inc., Alcoa Technical Center, GRAS, Inc., Touchstone Labs, and GKS Engineering Services. The Manufacturing process to make boron trichloride for grain refining is much simpler than preparing conventional grain refiners, with attendant environmental, capital, and energy savings. The manufacture of boride grain refining nuclei using the fy-Gem process avoids clusters, salt and oxide inclusions that cause quality problems in aluminum today.

  8. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, Peter (Inventor); Lederich, Richard J. (Inventor); O'Neal, James E. (Inventor)

    1989-01-01

    Three aluminum-lithium alloys are provided for high performance aircraft structures and engines. All three alloys contain 3 wt % copper, 2 wt % lithium, 1 wt % magnesium, and 0.2 wt % zirconium. Alloy 1 has no further alloying elements. Alloy 2 has the addition of 1 wt % iron and 1 wt % nickel. Alloy 3 has the addition of 1.6 wt % chromium to the shared alloy composition of the three alloys. The balance of the three alloys, except for incidentql impurities, is aluminum. These alloys have low densities and improved strengths at temperatures up to 260.degree. C. for long periods of time.

  9. PROCESS FOR REMOVING ALUMINUM COATINGS

    DOEpatents

    Flox, J.

    1959-07-01

    A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

  10. Aluminum Alloy 7068 Mechanical Characterization

    DTIC Science & Technology

    2009-08-01

    strength of 99 ksi (2). The commonly specified material properties for extruded 7068 aluminum are shown in table 1, along with 7050 and 7075 aluminum ...alloys for comparison (3). Table 1. Mechanical property comparison of high-strength aluminum alloys. Property Alloy 7068 7075 7050 Elastic... Aluminum Alloy 7068 Mechanical Characterization by Michael Minnicino, David Gray, and Paul Moy ARL-TR-4913 August 2009

  11. Low-pressure Structural Modification of Aluminum Hydride

    DTIC Science & Technology

    2011-02-01

    pressure release. 15. SUBJECT TERMS High - pressure , Diamond anvil cell, aluminum hydride 16. SECURITY CLASSIFICATION OF...loaded into the diamond anvil cell using a specialized high - pressure gas loading system (18). The in-situ pressure within the diamond anvil cell was...Visible Absorption Study of AlH3. Journal of Physics: Conference Series 2010, 215, 012047. 18. Jayaraman, A. Diamond Anvil Cell and High -

  12. Process for anodizing aluminum foil

    SciTech Connect

    Ball, J.A.; Scott, J.W.

    1984-11-06

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80/sup 0/ C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V.

  13. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  14. Aluminum adjuvants elicit fibrin-dependent extracellular traps in vivo

    PubMed Central

    Munks, Michael W.; McKee, Amy S.; MacLeod, Megan K.; Powell, Roger L.; Degen, Jay L.; Reisdorph, Nichole A.; Kappler, John W.

    2010-01-01

    It has been recognized for nearly 80 years that insoluble aluminum salts are good immunologic adjuvants and that they form long-lived nodules in vivo. Nodule formation has long been presumed to be central for adjuvant activity by providing an antigen depot, but the composition and function of these nodules is poorly understood. We show here that aluminum salt nodules formed within hours of injection and contained the clotting protein fibrinogen. Fibrinogen was critical for nodule formation and required processing to insoluble fibrin by thrombin. DNase treatment partially disrupted the nodules, and the nodules contained histone H3 and citrullinated H3, features consistent with extracellular traps. Although neutrophils were not essential for nodule formation, CD11b+ cells were implicated. Vaccination of fibrinogen-deficient mice resulted in normal CD4 T-cell and antibody responses and enhanced CD8 T-cell responses, indicating that nodules are not required for aluminum's adjuvant effect. Moreover, the ability of aluminum salts to retain antigen in the body, the well-known depot effect, was unaffected by the absence of nodules. We conclude that aluminum adjuvants form fibrin-dependent nodules in vivo, that these nodules have properties of extracellular traps, and the nodules are not required for aluminum salts to act as adjuvants. PMID:20876456

  15. Conference as Journey: Honouring Our Pedagogical Roots

    ERIC Educational Resources Information Center

    Asfeldt, Morten; Beames, Simon

    2012-01-01

    Most educators have spent many days and thousands of dollars attending academic conferences around the world, only to find themselves sitting in ballrooms, listening to speakers and watching PowerPoint presentations. In most cases, this conference format represents a profound pedagogical contradiction for outdoor and experiential educators. This…

  16. ALUMINUM AND CHROMIUM LEACHING WORKSHOP WHITEPAPER

    SciTech Connect

    McCabe, D; Jeff Pike, J; Bill Wilmarth, B

    2007-04-25

    A workshop was held on January 23-24, 2007 to discuss the status of processes to leach constituents from High Level Waste (HLW) sludges at the Hanford and Savannah River Sites. The objective of the workshop was to examine the needs and requirements for the HLW flowsheet for each site, discuss the status of knowledge of the leaching processes, communicate the research plans, and identify opportunities for synergy to address knowledge gaps. The purpose of leaching of non-radioactive constituents from the sludge waste is to reduce the burden of material that must be vitrified in the HLW melter systems, resulting in reduced HLW glass waste volume, reduced disposal costs, shorter process schedules, and higher facility throughput rates. The leaching process is estimated to reduce the operating life cycle of SRS by seven years and decrease the number of HLW canisters to be disposed in the Repository by 1000 [Gillam et al., 2006]. Comparably at Hanford, the aluminum and chromium leaching processes are estimated to reduce the operating life cycle of the Waste Treatment Plant by 20 years and decrease the number of canisters to the Repository by 15,000-30,000 [Gilbert, 2007]. These leaching processes will save the Department of Energy (DOE) billions of dollars in clean up and disposal costs. The primary constituents targeted for removal by leaching are aluminum and chromium. It is desirable to have some aluminum in glass to improve its durability; however, too much aluminum can increase the sludge viscosity, glass viscosity, and reduce overall process throughput. Chromium leaching is necessary to prevent formation of crystalline compounds in the glass, but is only needed at Hanford because of differences in the sludge waste chemistry at the two sites. Improving glass formulations to increase tolerance of aluminum and chromium is another approach to decrease HLW glass volume. It is likely that an optimum condition can be found by both performing leaching and improving

  17. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  18. Mechanisms of aluminum tolerance

    USDA-ARS?s Scientific Manuscript database

    Aluminum (Al) toxicity limits agricultural productivity over much of the world’s arable land by inhibiting root growth and development. Affected plants have difficulty in acquiring adequate water and nutrition from their soil environments and thus have stunted shoot development and diminished yield....

  19. Maize aluminum tolerance

    USDA-ARS?s Scientific Manuscript database

    Maize is one of the most economically important food crops grown on acid soils, where aluminum (Al) toxicity greatly limits crop yields. Considerable variation for Al tolerance exists in maize, and this variation has been exploited for many years by plant breeders to enhance maize Al tolerance. Curr...

  20. Markets for recovered aluminum

    SciTech Connect

    Not Available

    1993-04-01

    The study describes the operation of the markets for scrap aluminum as an example of how recycling markets are structured, what factors influence the supply of and demand for materials, what projections can be made about recycling markets, and how government policies to increase recycling may affect these markets.

  1. Building an aluminum car

    SciTech Connect

    Ashley, S.

    1994-05-01

    This article examines the increasing use of aluminum in automobiles to decrease weight and consequently increase fuel economy. The topics of the article include federal fuel economy goals, the development of optimum body structure and manufacturing techniques, comparison with steel, cost of materials, weight reduction and recycling of materials.

  2. Fluxless aluminum brazing

    DOEpatents

    Werner, W.J.

    1974-01-01

    This invention relates to a fluxless brazing alloy for use in forming brazed composites made from members of aluminum and its alloys. The brazing alloy consists of 35-55% Al, 10--20% Si, 25-60% Ge; 65-88% Al, 2-20% Si, 2--18% In; 65--80% Al, 15-- 25% Si, 5- 15% Y. (0fficial Gazette)

  3. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  4. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  5. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  6. REMOVAL OF ALUMINUM COATINGS

    DOEpatents

    Peterson, J.H.

    1959-08-25

    A process is presented for dissolving aluminum jackets from uranium fuel elements without attack of the uranium in a boiling nitric acid-mercuric nitrate solution containing up to 50% by weight of nitrtc acid and mercuric nitrate in a concentration of between 0.05 and 1% by weight.

  7. Bonding aluminum beam leads

    NASA Technical Reports Server (NTRS)

    Burkett, F. S.

    1978-01-01

    Report makes it relatively easy for hybrid-circuit manufacturers to convert integrated circuit chips with aluminum bead leads. Report covers: techniques for handling tiny chips; proper geometries for ultrasonic bonding tips; best combinations of pressure, pulse time, and ultrasonic energy for bonding; and best thickness for metal films to which beam leads are bonded.

  8. Next conference

    NASA Astrophysics Data System (ADS)

    Hexemer, Alexander; Toney, Michael F.

    2010-11-01

    After the successful conference on Synchrotron Radiation in Polymer Science (SRPS) in Rolduc Abbey (the Netherlands), we are now looking forward to the next meeting in this topical series started in 1995 by H G Zachmann, one of the pioneers of the use of synchrotron radiation techniques in polymer science. Earlier meetings were held in Hamburg (1995), Sheffield (2002), Kyoto (2006), and Rolduc (2009). In September of 2012 the Synchrotron Radiation and Polymer Science V conferences will be organized in a joint effort by the SLAC National Accelerator Laboratory and Lawrence Berkeley National Laboratory. Stanford Linear Accelerator Laboratory Stanford Linear Accelerator Laboratory Advanced Light Source at LBL Advanced Light Source at LBL The conference will be organised in the heart of beautiful San Francisco. The program will consist of invited and contributed lectures divided in sessions on the use of synchrotron SAXS/WAXD, imaging and tomography, soft x-rays, x-ray spectroscopy, GISAXS and reflectivity, micro-beams and hyphenated techniques in polymer science. Poster contributions are more than welcome and will be highlighted during the poster sessions. Visits to both SLAC as well as LBL will be organised. San Francisco can easily be reached. It is served by two major international airports San Francisco International Airport and Oakland International Airport. Both are being served by most major airlines with easy connections to Europe and Asia as well as national destinations. Both also boast excellent connections to San Francisco city centre. We are looking forward to seeing you in the vibrant city by the Bay in September 2012. Golden gate bridge Alexander Hexemer Lawrence Berkeley National Laboratory, Advanced Light Source, Berkeley, CA 94720, USA Michael F Toney Stanford Synchrotron Radiation Lightsource, Menlo Pk, CA 94025, USA E-mail: ahexemer@lbl.gov, mftoney@slac.stanford.edu

  9. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  10. Rapid manufacturing of aluminum components.

    PubMed

    Sercombe, T B; Schaffer, G B

    2003-08-29

    A manufacturing technique for the production of aluminum components is described. A resin-bonded part is formed by a rapid prototyping technique and then debound and infiltrated by a second aluminum alloy under a nitrogen atmosphere. During thermal processing, the aluminum reacts with the nitrogen and is partially transformed into a rigid aluminum nitride skeleton, which provides the structural rigidity during infiltration. The simplicity and rapidity of this process in comparison to conventional production routes, combined with the ability to fabricate complicated parts of almost any geometry and with high dimensional precision, provide an additional means to manufacture aluminum components.

  11. Conferences revisited

    NASA Astrophysics Data System (ADS)

    Radcliffe, Jonathan

    2008-08-01

    Way back in the mid-1990s, as a young PhD student, I wrote a Lateral Thoughts article about my first experience of an academic conference (Physics World 1994 October p80). It was a peach of a trip - most of the lab decamped to Grenoble for a week of great weather, beautiful scenery and, of course, the physics. A whole new community was there for me to see in action, and the internationality of it all helped us to forget about England's non-appearance in the 1994 World Cup finals.

  12. Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications

    NASA Astrophysics Data System (ADS)

    Hainey, Mel F.; Redwing, Joan M.

    2016-12-01

    Metal-mediated vapor-liquid-solid (VLS) growth is a promising approach for the fabrication of silicon nanowires, although residual metal incorporation into the nanowires during growth can adversely impact electronic properties particularly when metals such as gold and copper are utilized. Aluminum, which acts as a shallow acceptor in silicon, is therefore of significant interest for the growth of p-type silicon nanowires but has presented challenges due to its propensity for oxidation. This paper summarizes the key aspects of aluminum-catalyzed nanowire growth along with wire properties and device results. In the first section, aluminum-catalyzed nanowire growth is discussed with a specific emphasis on methods to mitigate aluminum oxide formation. Next, the influence of growth parameters such as growth temperature, precursor partial pressure, and hydrogen partial pressure on nanowire morphology is discussed, followed by a brief review of the growth of templated and patterned arrays of nanowires. Aluminum incorporation into the nanowires is then discussed in detail, including measurements of the aluminum concentration within wires using atom probe tomography and assessment of electrical properties by four point resistance measurements. Finally, the use of aluminum-catalyzed VLS growth for device fabrication is reviewed including results on single-wire radial p-n junction solar cells and planar solar cells fabricated with nanowire/nanopyramid texturing.

  13. Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications

    SciTech Connect

    Hainey, Mel F.; Redwing, Joan M.

    2016-12-15

    Metal-mediated vapor-liquid-solid (VLS) growth is a promising approach for the fabrication of silicon nanowires, although residual metal incorporation into the nanowires during growth can adversely impact electronic properties particularly when metals such as gold and copper are utilized. Aluminum, which acts as a shallow acceptor in silicon, is therefore of significant interest for the growth of p-type silicon nanowires but has presented challenges due to its propensity for oxidation. This paper summarizes the key aspects of aluminum-catalyzed nanowire growth along with wire properties and device results. In the first section, aluminum-catalyzed nanowire growth is discussed with a specific emphasis on methods to mitigate aluminum oxide formation. Next, the influence of growth parameters such as growth temperature, precursor partial pressure, and hydrogen partial pressure on nanowire morphology is discussed, followed by a brief review of the growth of templated and patterned arrays of nanowires. Aluminum incorporation into the nanowires is then discussed in detail, including measurements of the aluminum concentration within wires using atom probe tomography and assessment of electrical properties by four point resistance measurements. Finally, the use of aluminum-catalyzed VLS growth for device fabrication is reviewed including results on single-wire radial p-n junction solar cells and planar solar cells fabricated with nanowire/nanopyramid texturing.

  14. Behavior of aluminum in aluminum welders and manufacturers of aluminum sulfate--impact on biological monitoring.

    PubMed

    Riihimäki, Vesa; Valkonen, Sinikka; Engström, Bernt; Tossavainen, Antti; Mutanen, Pertti; Aitio, Antero

    2008-12-01

    The suitability of determining aluminum in serum or urine as a form of biological monitoring was critically assessed. Airborne and internal aluminum exposure was assessed for 12 aluminum welders in a shipyard and 5 manufacturers of aluminum sulfate. Particles were characterized with X-ray diffraction and scanning electron microscopy. Aluminum in air and biological samples was analyzed using electrothermal atomic absorption spectrometry. Basic toxicokinetic features were inferred from the data. The mean 8-hour time-weighted average concentration of aluminum was 1.1 (range 0.008-6.1) mg/m(3) for the shipyard and 0.13 (range 0.02-0.5) mg/m(3) for the aluminum sulfate plant. Welding fume contained aluminum oxide particles <0.1 microm in diameter and their agglomerates, whereas bauxite and aluminum sulfate particles ranged from 1 to 10 microm in diameter. The shipyard welders' mean postshift serum and urinary concentrations of aluminum (S-Al and U-Al, respectively) were 0.22 and 3.4 micromol/l, respectively, and the aluminum sulfate workers' corresponding values were 0.13 and 0.58 micromol/l. Between two shifts, the welders' S-Al concentration decreased by about 50% (P<0.01), but their U-Al concentration did not change (P=0.64). No corresponding temporal changes occurred among the aluminum sulfate workers. After aluminum welding at the shipyard had ceased, the median S-Al concentration decreased by about 50% (P=0.007) within a year, but there was no change (P=0.75) in the corresponding U-Al concentration. About 1% of aluminum in welding fume appears to be rapidly absorbed from the lungs, whereas an undetermined fraction is retained and forms a lung burden. A higher fractional absorption of aluminum seems possible for aluminum sulfate workers without evidence of a lung burden. After rapid absorption, aluminum is slowly mobilized from the lung burden and dominates the S-Al and U-Al concentrations of aluminum welders. For kinetic reasons, S-Al or U-Al concentrations cannot

  15. Aluminum electroplating on steel from a fused bromide electrolyte

    SciTech Connect

    Prabhat K. Tripathy; Laura A. Wurth; Eric J. Dufek; Toni Y. Gutknecht; Natalie J. Gese; Paula Hahn; Steven M. Frank; Guy L. Frederickson; J. Stephen Herring

    2014-08-01

    A quaternary bromide bath (LiBr–KBr–CsBr–AlBr3) was used to electro-coat aluminum on steel substrates. The electrolytewas prepared by the addition of AlBr3 into the eutectic LiBr–KBr–CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80 wt.% AlBr3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosionresistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminumcoating on both ferrous and non-ferrous metals, including complex surfaces/geometries.

  16. Nanoparticles of wurtzite aluminum nitride from the nut shells

    NASA Astrophysics Data System (ADS)

    Qadri, S. B.; Gorzkowski, E. P.; Rath, B. B.; Feng, C. R.; Amarasinghe, R.

    2016-11-01

    Nanoparticles of aluminum nitride were produced from a thermal treatment of a mixture of aluminum oxide (Al2O3) and shells of almond, cashew, coconuts, pistachio, and walnuts in a nitrogen atmosphere at temperatures in excess of 1450 °C. By selecting the appropriate ratios of each nut powder to Al2O3, it is shown that stoichiometric aluminum nitride can be produced by carbo-thermal reduction in nitrogen atmosphere. Using x-ray diffraction analysis, Raman scattering and Fourier Transform Infrared spectroscopy, it is demonstrated that aluminum nitride consists of pure wurtzite phase. Transmission electron microscopy showed the formation of nanoparticles and in some cases nanotubes of AlN.

  17. Aluminum toxicity and albumin.

    PubMed

    Kelly, A T; Short, B L; Rains, T C; May, J C; Progar, J J

    1989-01-01

    During a study of priming solutions for extracorporeal membrane oxygenation (ECMO) in the intensive care nursery, it was discovered that those solutions using certain brands of 25% albumin contained aluminum levels within the toxic range. When the brand was changed to a brand known to have a lower aluminum (Al) content, a marked drop in priming solution Al levels was measured. The heat exchanger was examined as a possible source of soluble Al. No evidence of elevated Al levels was found in fluids perfusing this heat exchanger when compared with a stainless steel heat exchanger. The Al content of various blood products was evaluated along with various brands of 5% albumin and 25% albumin.

  18. Degradation Mechanisms in Aluminum Matrix Composites: Alumina/Aluminum and Boron/Aluminum. Ph.D. Thesis - North Carolina State Univ. at Raleigh

    NASA Technical Reports Server (NTRS)

    Olsen, G. C.

    1981-01-01

    The effects of fabrication and long term thermal exposure (up to 10,000 hours at 590 K) on two types of aluminum matrix composites were examined. An alumina/aluminum composite, was made of continuous alpha Al2O3 fibers in a matrix of commercially pure aluminum alloyed with 2.8% lithium. The mechanical properties of the material, the effect of isothermal exposure, cyclic thermal exposure, and fatigue are presented. Two degradation mechanisms are identified. One was caused by formation of a nonstoichiometric alumina during fabrication, the other by a loss of lithium to a surface reaction during long term thermal exposure. The other composite, boron/aluminum, made of boron fibers in an aluminum matrix, was investigated using five different aluminum alloys for the matrices. The mechanical properties of each material and the effect of isothermal and cyclic thermal exposure are presented. The effects of each alloy constituent on the degradation mechanisms are discussed. The effects of several reactions between alloy constituents and boron fibers on the composite properties are discussed.

  19. Aluminum Alloy 7050 Extrusions.

    DTIC Science & Technology

    1977-03-01

    Artificial Aging Conditions 250 A-l Fatigue Crack Growth Data for C5A Extruded Panel, 7050-T7351X, L-T Orientation, R=0.1 254 A-2 Fatigue...cooldd aluminum and steel bottom blocks (Figure 2) were fabricated for use with this tooling. Metal was melted in a 10,000-lb capacity open- hearth ...time factor, effects of heating through this temperature range to the maximum artificial agirg temperature are additive. The solution of the

  20. Proposed Facility Quality Study Format. Proceedings of Statewide Higher Education Conference - Academic Planning, Facilities, Finance, Institutional Studies (Pigeon Lake Field Station, Drummond, Wisc., June 3-6, 1968).

    ERIC Educational Resources Information Center

    Riley, Robin O.

    A format considering factors to be studied in a proposed obsolescence formula. Items listed under the physical characteristics category are intended to be subjected to a technical evaluation under which the condition and adequacy of the building and building system may be subsequently measured as a yardstick of the building's present and future…

  1. Silicon diffusion in aluminum for rear passivated solar cells

    SciTech Connect

    Urrejola, Elias; Peter, Kristian; Plagwitz, Heiko; Schubert, Gunnar

    2011-04-11

    We show that the lateral spread of silicon in a screen-printed aluminum layer increases by (1.50{+-}0.06) {mu}m/ deg. C, when increasing the peak firing temperature within an industrially applicable range. In this way, the maximum spread limit of diffused silicon in aluminum is predictable and does not depend on the contact area size but on the firing temperature. Therefore, the geometry of the rear side pattern can influence not only series resistance losses within the solar cell but the process of contact formation itself. In addition, too fast cooling lead to Kirkendall void formations instead of an eutectic layer.

  2. Effects of various additives on sintering of aluminum nitride

    NASA Technical Reports Server (NTRS)

    Komeya, K.; Inoue, H.; Tsuge, A.

    1982-01-01

    Effects of thirty additives on sintering A/N were investigated. The addition of alkali earth oxides and rare earth oxides gave fully densified aluminum nitride. This is due to the formation of nitrogen-containing aluminate liquid in the system aluminum nitride-alkali earth oxides or rare earth oxides. Microstructural studies of the sintered specimens with the above two types of additives suggested that the densification was due to the liquid phase sintering. Additions of silicon compounds resulted in poor densification by the formation of highly refractory compounds such as A/N polytypes.

  3. Effect of uniform magnetic and electric fields on microstructure and substructure characteristics of combustion products of aluminum nanopowder in air

    NASA Astrophysics Data System (ADS)

    Il'in, A. P.; Mostovshchikov, A. V.; Pak, A. Ya.

    2016-12-01

    We have analyzed the effect of constant electric and magnetic fields on the micro- and substructure characteristics of the combustion products of aluminum nanopowder in air. It has been found that the combustion of aluminum nanopowder in a magnetic field leads to the formation of single crystals of the hexagonal habitus, while the combustion in an electric field results in the formation of faceted crystallites with layered morphology. The fields noticeably affect the crystal lattice parameters of aluminum oxide and nitride (reduce the coherent scattering regions in aluminum nitride and increase such regions in aluminum γ-oxide). At the same time, the displacement of atoms relative to the equilibrium position becomes noticeably smaller for all crystal phases under the action of the fields (except for aluminum nitride in a magnetic field). These results have been explained by the orienting and stabilizing actions of the fields on the combustion products of aluminum nanopowder in air.

  4. Avoidance of aluminum by rainbow trout

    SciTech Connect

    Exley, C.

    2000-04-01

    Aluminum is the principal toxicant in fish in acid waters. The ability to avoid Al, particularly at low concentrations, would confer a considerable ecological advantage, but previous research into avoidance of Al has produced mixed results. The author used a cylindrical perspex tank, 150 cm in length, to study avoidance of Al by rainbow trout fry. The fish avoided Al, and their response was dependent on pH. Avoidance that was demonstrated at pHs of 5.00, 5.50, 5.50, and 5.75 was abolished at a pH of 6.00. Fry avoided very low Al concentrations being sensitive to [Al] > 1.00 {micro}mol L{sup {minus}1} at a pH of 5.00. This unequivocal demonstration of avoidance by rainbow trout fry of Al may have important implications for the ecology of indigenous fish populations in surface waters impacted by acidic deposition.

  5. Vacancy Mechanism of the Photolysis of Aluminum Hydride

    NASA Astrophysics Data System (ADS)

    Goryaev, M. A.

    2000-01-01

    Within the framework of the thermodynamic model of formation of intrinsic defects in a lattice during the decay of photoexcitations in a solid, the formation of hydrogen vacancies in aluminum hydride is analyzed. The evolution of a system with excess vacancy concentration leads to the formation of micropores under the crystal surface. The results of calculations agree well with the experimental data on photochemically induced absorption obtained in electron-microscopic studies of AlH3 decomposition.

  6. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  7. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  8. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  9. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  10. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum. It...

  11. Aluminum Carbothermic Technology

    SciTech Connect

    Bruno, Marshall J.

    2005-03-31

    This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major

  12. Extracting aluminum from dross tailings

    NASA Astrophysics Data System (ADS)

    Amer, A. M.

    2002-11-01

    Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.

  13. Filamentation and spatiotemporal distribution of extracellular polymeric substances: role on X.fastidiosa single cell adhesion and biofilm formation (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Janissen, Richard; Murillo, Duber M.; Niza, Barbara; Sahoo, Prasana K.; Monteiro, Moniellen P.; César, Carlos L.; Carvalho, Hernandes F.; de Souza, Alessandra A.; Cotta, Monica A.

    2016-04-01

    Biofilms can be defined as a community of microorganisms attached to a surface, living embedded in a self- produced matrix of hydrated extracellular polymeric substances (EPS) which comprises most of the biofilm mass. We have recently used an extensive pool of microscopy techniques (confocal fluorescence, electron and scanning probe microscopies) at the micro and nanoscales in order to create a detailed temporal observation of Xylella fastidiosa biofilm formation, using both wild type strain and Green Fluorescent Protein (GFP)-modified cells of this citrus phytopathogen. We have identified three different EPS compositions, as well as their spatial and temporal distribution from single cell to mature biofilm formation stages. In the initial adhesion stage, soluble-EPS (S-EPS) accumulates at cell polar regions and forms a surface layer which facilitates irreversible cell attachment and cell cluster formation. These small clusters are subsequently connected by filamentous cells; further S-EPS surface coverage facilitates cell attachment and form filaments, leading to a floating framework of mature biofilms. The important role of EPS in X.fastidiosa biology was further investigated by imunolabelling experiments to detect the distribution of XadA1 adhesin, which is expressed in early stages of biofilm formation and released in outer membrane vesicles. This protein is located mainly in S-EPS covered areas, as well as on the filaments, indicating a molecular pathway to the enhanced cell attachment previously observed. These results suggest that S-EPS may thus represent an important target for disease control, slow plant colonization by the bacteria, keeping the plant more productive in the field.

  14. FE-simulation of laser assisted joining of aluminum-steel

    NASA Astrophysics Data System (ADS)

    Liedl, Gerhard; Pospichal, Robert

    2012-01-01

    Laser assisted joining of aluminum and steel causes the formation of intermetallic compounds. Especially compounds with high aluminum content should be avoided due to their high brittleness. Excellent experimental results where joining and cooling temperatures have been optimised are presented. A FE software package has been used to simulate temperature development during laser assisted joining of dissimilar materials.

  15. Brazing process provides high-strength bond between aluminum and stainless steel

    NASA Technical Reports Server (NTRS)

    Huschke, E. G., Jr.; Nord, D. B.

    1966-01-01

    Brazing process uses vapor-deposited titanium and an aluminum-zirconium-silicon alloy to prevent formation of brittle intermetallic compounds in stainless steel and aluminum bonding. Joints formed by this process maintain their high strength, corrosion resistance, and hermetic sealing properties.

  16. Carbon Nanotube Aluminum Matrix Composites

    DTIC Science & Technology

    2010-08-01

    replacement of air space with the polymer matrix. A similar affinity is not known to exist between CNTs and aluminum , where the wetting angle between...Carbon Nanotube Aluminum Matrix Composites by Brent J. Carey, Jerome T. Tzeng, and Shashi Karna ARL-TR-5252 August 2010...Nanotube Aluminum Matrix Composites Brent J. Carey, Jerome T. Tzeng, and Shashi Karna Weapons and Materials Research Directorate, ARL

  17. Exposure assessment of aluminum arc welding radiation.

    PubMed

    Peng, Chiung-yu; Lan, Cheng-hang; Juang, Yow-jer; Tsao, Ta-ho; Dai, Yu-tung; Liu, Hung-hsin; Chen, Chiou-jong

    2007-10-01

    The purpose of this study is to evaluate the non-ionizing radiation (NIR) exposure, especially optical radiation levels, and potential health hazard from aluminum arc welding processes based on the American Conference of Governmental Industrial Hygienists (ACGIH) method. The irradiance from the optical radiation emissions can be calculated with various biological effective parameters [i.e., S(lambda), B(lambda), R(lambda)] for NIR hazard assessments. The aluminum arc welding processing scatters bright light with NIR emission including ultraviolet radiation (UVR), visible, and infrared spectra. The UVR effective irradiance (Eeff) has a mean value of 1,100 microW cm at 100 cm distance from the arc spot. The maximum allowance time (tmax) is 2.79 s according to the ACGIH guideline. Blue-light hazard effective irradiance (EBlue) has a mean value of 1840 microW cm (300-700 nm) at 100 cm with a tmax of 5.45 s exposure allowance. Retinal thermal hazard effective calculation shows mean values of 320 mW cm(-2) sr(-1) and 25.4 mW (cm-2) (380-875 nm) for LRetina (spectral radiance) and ERetina (spectral irradiance), respectively. From this study, the NIR measurement from welding optical radiation emissions has been established to evaluate separate types of hazards to the eye and skin simultaneously. The NIR exposure assessment can be applied to other optical emissions from industrial sources. The data from welding assessment strongly suggest employees involved in aluminum welding processing must be fitted with appropriate personal protection devices such as masks and gloves to prevent serious injuries of the skin and eyes upon intense optical exposure.

  18. Effects of organic solutes on chemical reactions of aluminum

    USGS Publications Warehouse

    Lind, Carol J.; Hem, John David

    1975-01-01

    Concentrations of organic matter in the general range of 1-10 milligrams per litre organic carbon are common in natural water, and many naturally occurrin7 organic compounds form aluminum complexes. The aluminum concentrations in near-neutral pH solutions may be 10-100 times higher than the values predicted from solubility data if formation of such organic complexes is ignored. The processes of polymerization of aluminum hydroxide and precipitation of gibbsite are inhibited by the presence of the organic flavone compound quercetin in concentrations as low as 10 x -5.3 mole per litre. Quercetin forms a complex, with a probable molar ratio of 1:2 aluminum to quercetin, that has a formation constant (f12) of about 10 12. A complex with a higher aluminum-quercetin ratio also was observed, but this material tends to evolve into a compound of low solubility that removes aluminum from solution. In the presence of both dissolved aluminum and aqueous silica, low concentrations of quercetin improved the yield of crystallized kaolinite and halloysite. Small amounts of well-shaped kaolinite and halloysite crystals were identified by electron microscopy in solutions with pH's in the range 6.5-8.5 after 155 days aging in one experimer t and 481 days aging in a repeated experiment. The bulk of the precipitated material was amorphous to X-rays, and crystalline material was too small a proportion of the total to give identifiable X-ray diffraction peaks. The precipitates had aluminum-silicon ratios near 1, and their solubility corresponded to that found by Hem, Roberson, Lind, and Polzer (1973) for similar aluminosilicate precipitated in the absence of organic solutes. The improved yield of crystalline material obtained in the presence of quercetin probably is the result of the influence of the organic compound on the aluminum hydroxide polymerization process. Natural water containing color imparted by organic material tends to be higher in aluminum than would be predicted by p

  19. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  20. Mineral of the month: aluminum

    USGS Publications Warehouse

    Plunkert, Patricia A.

    2005-01-01

    Aluminum is the second most abundant metallic element in Earth’s crust after silicon. Even so, it is a comparatively new industrial metal that has been produced in commercial quantities for little more than 100 years. Aluminum is lightweight, ductile, malleable and corrosion resistant, and is a good conductor of heat and electricity. Weighing about one-third as much as steel or copper per unit of volume, aluminum is used more than any other metal except iron. Aluminum can be fabricated into desired forms and shapes by every major metalworking technique to add to its versatility.

  1. Plant adaptation to acid soils: the molecular basis for crop aluminum resistance

    USDA-ARS?s Scientific Manuscript database

    Aluminum (Al) toxicity on acid soils is a significant limitation to crop production worldwide, as approximately 50% of the world’s potentially arable soils are acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring resistance to ...

  2. Unified model of plasma formation, bubble generation and shock wave emission in water for fs to ns laser pulses (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Liang, Xiao-Xuan; Freidank, Sebastian; Linz, Norbert; Paltauf, Günther; Zhang, Zhenxi; Vogel, Alfred

    2017-03-01

    We developed modeling tools for optical breakdown events in water that span various phases reaching from breakdown initiation via solvated electron generation, through laser induced-plasma formation and temperature evolution in the focal spot to the later phases of cavitation bubble dynamics and shock wave emission and applied them to a large parameter space of pulse durations, wavelengths, and pulse energies. The rate equation model considers the interplay of linear absorption, photoionization, avalanche ionization and recombination, traces thermalization and temperature evolution during the laser pulse, and portrays the role of thermal ionization that becomes relevant for T > 3000 K. Modeling of free-electron generation includes recent insights on breakdown initiation in water via multiphoton excitation of valence band electrons into a solvated state at Eini = 6.6 eV followed by up-conversion into the conduction band level that is located at 9.5 eV. The ability of tracing the temperature evolution enabled us to link the model of laser-induced plasma formation with a hydrodynamic model of plasma-induced pressure evolution and phase transitions that, in turn, traces bubble generation and dynamics as well as shock wave emission. This way, the amount of nonlinear energy deposition in transparent dielectrics and the resulting material modifications can be assessed as a function of incident laser energy. The unified model of plasma formation and bubble dynamics yields an excellent agreement with experimental results over the entire range of investigated pulse durations (femtosecond to nanosecond), wavelengths (UV to IR) and pulse energies.

  3. Conference Summary

    NASA Astrophysics Data System (ADS)

    Sanders, David B.

    2014-07-01

    This conference on ``Multi-wavelength AGN Surveys and Studies'' has provided a detailed look at the explosive growth over the past decade, of available astronomical data from a growing list of large scale sky surveys, from radio-to-gamma rays. We are entering an era were multi-epoch (months to weeks) surveys of the entire sky, and near-instantaneous follow-up observations of variable sources, are elevating time-domain astronomy to where it is becoming a major contributor to our understanding of Active Galactic Nuclei (AGN). While we can marvel at the range of extragalactic phenomena dispayed by sources discovered in the original ``Markarian Survey'' - the first large-scale objective prism survey of the Northern Sky carried out at the Byurakan Astronomical Observtory almost a half-century ago - it is clear from the talks and posters presented at this meeting that the data to be be obtained over the next decade will be needed if we are to finally understand which phase of galaxy evolution each Markarian Galaxy represents.

  4. Production of aluminum metal by electrolysis of aluminum sulfide

    DOEpatents

    Minh, Nguyen Q.; Loutfy, Raouf O.; Yao, Neng-Ping

    1984-01-01

    Production of metallic aluminum by the electrolysis of Al.sub.2 S.sub.3 at 700.degree.-800.degree. C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

  5. Production of aluminum metal by electrolysis of aluminum sulfide

    DOEpatents

    Minh, N.Q.; Loutfy, R.O.; Yao, N.P.

    1982-04-01

    Metallic aluminum may be produced by the electrolysis of Al/sub 2/S/sub 3/ at 700 to 800/sup 0/C in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

  6. Production of aluminum metal by electrolysis of aluminum sulfide

    SciTech Connect

    Minh, N.Q.; Loutfy, R.O.; Yao, N.P.

    1984-08-07

    A method is disclosed for production of metallic aluminum by the electrolysis of A1/sub 2/S/sub 3/ at 700/sup 0/-800/sup 0/ C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

  7. Effect of grain orientation on aluminum relocation at incipient melt conditions

    DOE PAGES

    Yilmaz, Nadir; Vigil, Francisco M.; Vigil, Miquela S.; ...

    2015-09-01

    Aluminum is commonly used for structural applications in the aerospace industry because of its high strength in relation to its weight. It is necessary to understand the mechanical response of aluminum structures at elevated temperatures such as those experienced in a fire. Additionally, aluminum alloys exhibit many complicated behaviors that require further research and understanding, such as aluminum combustion, oxide skin formation and creep behavior. This paper discusses the effect of grain orientation on aluminum deformation subjected to heating at incipient melt conditions. Experiments were conducted by applying a vertical compressive force to aluminum alloy 7075 block test specimens. Furthermore,more » compression testing was done on test specimens with the applied load on the long transverse and short transverse orientations. Our results showed that the grain orientation significantly influences aluminum’s strength and mode of failure.« less

  8. Effect of grain orientation on aluminum relocation at incipient melt conditions

    SciTech Connect

    Yilmaz, Nadir; Vigil, Francisco M.; Vigil, Miquela S.; Branam, Robert; Tolendino, Greg; Gill, Walt; Burl Donaldson, A.

    2015-09-01

    Aluminum is commonly used for structural applications in the aerospace industry because of its high strength in relation to its weight. It is necessary to understand the mechanical response of aluminum structures at elevated temperatures such as those experienced in a fire. Additionally, aluminum alloys exhibit many complicated behaviors that require further research and understanding, such as aluminum combustion, oxide skin formation and creep behavior. This paper discusses the effect of grain orientation on aluminum deformation subjected to heating at incipient melt conditions. Experiments were conducted by applying a vertical compressive force to aluminum alloy 7075 block test specimens. Furthermore, compression testing was done on test specimens with the applied load on the long transverse and short transverse orientations. Our results showed that the grain orientation significantly influences aluminum’s strength and mode of failure.

  9. Photoemission study of tris(8-hydroxyquinoline) aluminum/aluminum oxide/tris(8-hydroxyquinoline) aluminum interface

    SciTech Connect

    Ding Huanjun; Zorba, Serkan; Gao Yongli; Ma Liping; Yang Yang

    2006-12-01

    The evolution of the interface electronic structure of a sandwich structure involving aluminum oxide and tris(8-hydroxyquinoline) aluminum (Alq), i.e. (Alq/AlO{sub x}/Alq), has been investigated with photoemission spectroscopy. Strong chemical reactions have been observed due to aluminum deposition onto the Alq substrate. The subsequent oxygen exposure releases some of the Alq molecules from the interaction with aluminum. Finally, the deposition of the top Alq layer leads to an asymmetry in the electronic energy level alignment with respect to the AlO{sub x} interlayer.

  10. Critical properties of aluminum.

    PubMed

    Bhatt, Divesh; Jasper, Ahren W; Schultz, Nathan E; Siepmann, J Ilja; Truhlar, Donald G

    2006-04-05

    Gibbs ensemble Monte Carlo calculations are performed using a validated embedded-atom potential to obtain the vapor-liquid coexistence curve for elemental aluminum in good agreement with available experimental data up to the boiling point. These calculations are then extended to make a reliable prediction of the critical temperature, pressure, and density of Al, which have previously been known only with very large uncertainties. This demonstrates the ability of modern simulations to predict fundamental physical properties that are extremely difficult to measure directly.

  11. Characterization of ultradispersed aluminum

    SciTech Connect

    Simpson, R.L.; Maienschein, J.L.; Swansiger, R.W.; Garcia, F.; Darling, D.H.

    1994-12-08

    Samples of ultradispersed Al were received, which were produced by electrically exploding Al wires in argon. These samples comprised very small particles that were not significantly oxidized and that were stable in air. Particle morphology were studied with SE, micropycnometry, and gas adsorption surface area. Composition were determined using various techniques, as were thermal stability and reaction exotherms. The inexplicable reports of an Al-Ar compound and of an exothermic reaction were not confirmed. The material is a stable, nonoxidized, small-particle, highly reactive form of aluminum that is of interest in energetic materials formulations.

  12. Aluminum nitride grating couplers.

    PubMed

    Ghosh, Siddhartha; Doerr, Christopher R; Piazza, Gianluca

    2012-06-10

    Grating couplers in sputtered aluminum nitride, a piezoelectric material with low loss in the C band, are demonstrated. Gratings and a waveguide micromachined on a silicon wafer with 600 nm minimum feature size were defined in a single lithography step without partial etching. Silicon dioxide (SiO(2)) was used for cladding layers. Peak coupling efficiency of -6.6 dB and a 1 dB bandwidth of 60 nm have been measured. This demonstration of wire waveguides and wideband grating couplers in a material that also has piezoelectric and elasto-optic properties will enable new functions for integrated photonics and optomechanics.

  13. Aluminum Citrate Prevents Renal Injury from Calcium Oxalate Crystal Deposition

    PubMed Central

    Besenhofer, Lauren M.; Cain, Marie C.; Dunning, Cody

    2012-01-01

    Calcium oxalate monohydrate crystals are responsible for the kidney injury associated with exposure to ethylene glycol or severe hyperoxaluria. Current treatment strategies target the formation of calcium oxalate but not its interaction with kidney tissue. Because aluminum citrate blocks calcium oxalate binding and toxicity in human kidney cells, it may provide a different therapeutic approach to calcium oxalate-induced injury. Here, we tested the effects of aluminum citrate and sodium citrate in a Wistar rat model of acute high-dose ethylene glycol exposure. Aluminum citrate, but not sodium citrate, attenuated increases in urea nitrogen, creatinine, and the ratio of kidney to body weight in ethylene glycol–treated rats. Compared with ethylene glycol alone, the addition of aluminum citrate significantly increased the urinary excretion of both crystalline calcium and crystalline oxalate and decreased the deposition of crystals in renal tissue. In vitro, aluminum citrate interacted directly with oxalate crystals to inhibit their uptake by proximal tubule cells. These results suggest that treating with aluminum citrate attenuates renal injury in rats with severe ethylene glycol toxicity, apparently by inhibiting calcium oxalate’s interaction with, and retention by, the kidney epithelium. PMID:23138489

  14. Bronchopulmonary Cellular Response to Aluminum and Zirconium Salts

    PubMed Central

    Stankus, Richard P.; Schuyler, Mark R.; D'Amato, Robert A.; Salvaggio, John E.

    1978-01-01

    The bronchopulmonary cellular immunological response to repeated intratracheal inoculation of aluminum chlorhydrate, sodium zirconium lactate, and zirconium aluminum glycine was examined in rabbits. Results of a dose-response experiment using 0.1, 1.0, and 10.0-mg intratracheal inoculations of each metallic salt demonstrated significant bronchopulmonary histopathology in the 10.0-mg dose-response groups only. Acute lesions were histologically characterized by an inflammatory response centered around respiratory bronchioles. Although epithelioid cell formation was evident in 10.0 mg of aluminum salt (aluminum chlorhydrate and zirconium aluminum glycine) -injected animals, no well-defined granulomas characterized by an orderly arrangement of epithelioid cells, lymphocytes, and giant cells were evident in any of the experimental groups employed. All three metallic salts induced “activated” bronchopulmonary macrophages as determined by an in vitro phagocytic assay. This activation was likely nonimmunological since no measurable differences were observed in metallic salt-induced delayed skin reactivity or migration inhibition factor production between inoculated and uninoculated rabbits. The above observations suggest that aluminum and zirconium salts administered in comparatively high dosage via the respiratory tract route can induce respiratory bronchiolitis and activation of alveolar macrophages in the absence of demonstrable delayed hypersensitivity. Images PMID:352963

  15. Environmental dust effects on aluminum surfaces in humid air ambient.

    PubMed

    Yilbas, Bekir Sami; Hassan, Ghassan; Ali, Haider; Al-Aqeeli, Nasser

    2017-04-05

    Environmental dusts settle on surfaces and influence the performance of concentrated solar energy harvesting devices, such as aluminum troughs. The characteristics of environmental dust and the effects of mud formed from the dust particles as a result of water condensing in humid air conditions on an aluminum wafer surface are examined. The dissolution of alkaline and alkaline earth compounds in water condensate form a chemically active mud liquid with pH 8.2. Due to gravity, the mud liquid settles at the interface of the mud and the aluminum surface while forming locally scattered patches of liquid films. Once the mud liquid dries, adhesion work to remove the dry mud increases significantly. The mud liquid gives rise to the formation of pinholes and local pit sites on the aluminum surface. Morphological changes due to pit sites and residues of the dry mud on the aluminum surface lower the surface reflection after the removal of the dry mud from the surface. The characteristics of the aluminum surface can address the dust/mud-related limitations of reflective surfaces and may have implications for the reductions in the efficiencies of solar concentrated power systems.

  16. Environmental dust effects on aluminum surfaces in humid air ambient

    PubMed Central

    Yilbas, Bekir Sami; Hassan, Ghassan; Ali, Haider; Al-Aqeeli, Nasser

    2017-01-01

    Environmental dusts settle on surfaces and influence the performance of concentrated solar energy harvesting devices, such as aluminum troughs. The characteristics of environmental dust and the effects of mud formed from the dust particles as a result of water condensing in humid air conditions on an aluminum wafer surface are examined. The dissolution of alkaline and alkaline earth compounds in water condensate form a chemically active mud liquid with pH 8.2. Due to gravity, the mud liquid settles at the interface of the mud and the aluminum surface while forming locally scattered patches of liquid films. Once the mud liquid dries, adhesion work to remove the dry mud increases significantly. The mud liquid gives rise to the formation of pinholes and local pit sites on the aluminum surface. Morphological changes due to pit sites and residues of the dry mud on the aluminum surface lower the surface reflection after the removal of the dry mud from the surface. The characteristics of the aluminum surface can address the dust/mud-related limitations of reflective surfaces and may have implications for the reductions in the efficiencies of solar concentrated power systems. PMID:28378798

  17. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  18. Intelligent control of vacuum aluminum brazing

    SciTech Connect

    Zhong, G.; Pai, D.M.; Badgley, S.

    1995-06-01

    Vacuum brazing is a versatile modern day metal joining method. It usually includes vacuum producing, heating and residual gas analyzing systems. When used to join aluminum parts, the quality of the brazed joint is highly dependent on the residual gases in the vacuum, especially the residual oxygen and water vapor in the vacuum chamber which affect the formation of oxides. These vacuum environment brazing contaminants are reduced during the out-gassing processes of degassing and desorption during heating under vacuum. Exceeding the boundary limits of these contaminants causes unacceptable flow of braze filler in the joints during the brazing process. Identification of the quality control boundary for vacuum brazing of aluminum alloy makes computer control of vacuum brazing quality for aluminum alloys possible. The present study utilizes a residual gas analyzer (RGA) to monitor the partial pressures of residual gases during brazing. These data are transported to computer through the RS-232 interface port on the RGA, and used in real time to monitor the brazing quality by an algorithm based on the quality control boundary. If the quality is bad, the computer will send a ``hold`` signal to the heating system via another Rs-232 port until the environment is reestablished within the acceptable boundary.

  19. Sonolytic desorption of mercury from aluminum oxide.

    PubMed

    He, Ziqi; Traina, Samuel J; Bigham, Jerry M; Weavers, Linda K

    2005-02-15

    As discrete particles and/or as coatings on other mineral surfaces in natural systems, aluminum (hydr)oxides are efficient sinks for Hg(II). Ultrasound at 20 kHz was applied to enhance the desorption of Hg(II) from aluminum oxide particles (5.0 micromol of Hg g(-1)). Results showed that at short times ultrasound enhanced Hg(II) release at pH 4.0 compared to both that from hydrodynamic mixing and that expected on the basis of the Hg(II) sorption isotherm. The higher the input power of sonication, the higher the desorption of Hg(II). However, with longer times, much less desorption occurred by ultrasound than by hydrodynamic mixing, with mass balance measurements demonstrating that the desorbed Hg(II) was resorbed back to the particles. The particles were characterized to explore the mechanism for resorption of Hg(II) by prolonged sonication. No surface area change was observed even though ultrasound dramatically reduced the particle size and changed the surface morphology. Although a decrease in the point of zero charge (PZC) due to sonication was observed, it was excluded as the primary mechanism for Hg(II) resorption. Hg(II) occlusion by aluminum hydroxide precipitation was supported by X-ray photoelectron spectroscopy results and the formation of solutions supersaturated with AI. Experiments on presonicated particles verified the occlusion theory by ruling out the effects of the surface area and PZC.

  20. Conference Scene

    PubMed Central

    Leeder, J Steven; Lantos, John; Spielberg, Stephen P

    2015-01-01

    A major challenge for clinicians, pharmaceutical companies and regulatory agencies is to better understand the relative contributions of ontogeny and genetic variation to observed variability in drug disposition and response across the pediatric age spectrum from preterm and term newborns, to infants, children and adolescents. Extrapolation of adult experience with pharmacogenomics and personalized medicine to pediatric patients of different ages and developmental stages, is fraught with many challenges. Compared with adults, pediatric pharmacogenetics and pharmacogenomics involves an added measure of complexity as variability owing to developmental processes, or ontogeny, is superimposed upon genetic variation. Furthermore, some pediatric diseases have no adult correlate or are more prevalent in children compared with adults, and several adverse drug reactions are unique to children, or occur at a higher frequency in children. The primary objective of this conference was to initiate an ongoing series of annual meetings on ‘Pediatric Pharmacogenomics and Personalized Medicine’ organized by the Center for Personalized Medicine and Therapeutic Innovation and Division of Clinical Pharmacology and Medical Therapeutics at Children’s Mercy Hospitals and Clinics in Kansas City, MO, USA. The primary goals of the inaugural meeting were: to bring together clinicians, basic and translational scientists and allied healthcare practitioners, and engage in a multi- and cross-disciplinary dialog aimed at implementing personalized medicine in pediatric settings; to provide a forum for the presentation and the dissemination of research related to the application of pharmacogenomic strategies to investigations of variability of drug disposition and response in children; to explore the ethical, legal and societal implications of pharmacogenomics and personalized medicine that are unique to children; and finally, to create networking opportunities for stimulating discussion

  1. Aluminum Nanoholes for Optical Biosensing.

    PubMed

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor; Herranz, Sonia; Urraca, Javier; Moreno-Bondi, María Cruz; Avella-Oliver, Miquel; Maquieira, Ángel; Puchades, Rosa

    2015-07-09

    Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation--which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports--the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs.

  2. Aluminum Nanoholes for Optical Biosensing

    PubMed Central

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor; Herranz, Sonia; Urraca, Javier; Moreno-Bondi, María Cruz; Avella-Oliver, Miquel; Maquieira, Ángel; Puchades, Rosa

    2015-01-01

    Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation—which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports—the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs. PMID:26184330

  3. Aluminum-Lead Composite Materials

    NASA Astrophysics Data System (ADS)

    Kovtunov, A. I.; Khokhlov, Yu. Yu.; Myamin, S. V.

    2017-05-01

    A process of fabrication of aluminum-lead sliding bearings is suggested on the basis of impregnation of foam aluminum with lead or lead-base alloys. The results of tests of physical, mechanical and operating properties of the composite materials are presented.

  4. The Benefits of Aluminum Windows.

    ERIC Educational Resources Information Center

    Goyal, R. C.

    2002-01-01

    Discusses benefits of aluminum windows for college construction and renovation projects, including that aluminum is the most successfully recycled material, that it meets architectural glass deflection standards, that it has positive thermal energy performance, and that it is a preferred exterior surface. (EV)

  5. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  6. Measuring Hydrogen Properties in Aluminum

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.

    1982-01-01

    System in use at Langley Research Center measures concentration and diffusion coefficient of hydrogen in pure aluminum. Principal components are high-temperature ultra-high-vacuum furnace and quadrupole mass spectrometer. Quantities of hydrogen and other gases that evolve from heated metal are measured in real time and correlated with data on aluminum porosity.

  7. The Benefits of Aluminum Windows.

    ERIC Educational Resources Information Center

    Goyal, R. C.

    2002-01-01

    Discusses benefits of aluminum windows for college construction and renovation projects, including that aluminum is the most successfully recycled material, that it meets architectural glass deflection standards, that it has positive thermal energy performance, and that it is a preferred exterior surface. (EV)

  8. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  9. Primary Aluminum Plants Worldwide - 1998

    USGS Publications Warehouse

    1999-01-01

    The 1990 U.S. Bureau of Mines publication, Primary Aluminum Plants Worldwide, has been updated and is now available. The 1998 USGS edition of Primary Aluminum Plants Worldwide is published in two parts. Part I—Detail contains information on individual primary smelter capacity, location, ownership, sources of energy, and other miscellaneous information. Part II—Summary summarizes the capacity data by country

  10. Aluminum alloys for aerostructures

    SciTech Connect

    Staley, J.T.; Liu, J.; Hunt, W.H. Jr.

    1997-10-01

    Demands on the airframe industry have shifted over the years, but they have always moved in the direction of lower weight, higher damage tolerance, and longer-term durability. Up to the 1960s, the greatest need was for high strength to reduce weight. In the 1970s, higher fracture toughness and corrosion resistance were sought for enhanced damage tolerance and durability. In the early 1980s, the requirement for reduced weight was renewed, but by the late 1980s and early 1990s, durability became a concern again. Today`s focus is on materials that can help achieve low-cost manufacturing without sacrificing performance; future needs are likely to include both affordability and higher performance. This article describes the development of high-strength aluminum alloy materials that have satisfied past and current requirements, and identifies possible aluminum-intensive approaches that combine alternate design concepts and emerging materials technologies for low-cost, low-weight, damage-tolerant, and durable airframe structures of the future.

  11. Hot Extrusion of Aluminum Chips

    NASA Astrophysics Data System (ADS)

    Tekkaya, A. Erman; Güley, Volkan; Haase, Matthias; Jäger, Andreas

    The process of hot extrusion is a promising approach for the direct recycling of aluminum machining chips to aluminum profiles. The presented technology is capable of saving energy, as remelting of aluminum chips can be avoided. Depending on the deformation route and process parameters, the chip-based aluminum extradates showed mechanical properties comparable or superior to cast aluminum billets extruded under the same conditions. Using different metal flow schemes utilizing different extrusion dies the mechanical properties of the profiles extruded from chips can be improved. The energy absorption capacity of the profiles the rectangular hollow profiles extruded from chips and as-cast billets were analyzed using the drop hammer test set-up. The formability of the profiles extruded from chips and as-cast material were compared using tube bending tests in a three-roller-bending machine.

  12. Wettability of Aluminum on Alumina

    NASA Astrophysics Data System (ADS)

    Bao, Sarina; Tang, Kai; Kvithyld, Anne; Tangstad, Merete; Engh, Thorvald Abel

    2011-12-01

    The wettability of molten aluminum on solid alumina substrate has been investigated by the sessile drop technique in a 10-8 bar vacuum or under argon atmosphere in the temperature range from 1273 K to 1673 K (1000 °C to 1400 °C). It is shown that the reduction of oxide skin on molten aluminum is slow under normal pressures even with ultralow oxygen potential, but it is enhanced in high vacuum. To describe the wetting behavior of the Al-Al2O3 system at lower temperatures, a semiempirical calculation was employed. The calculated contact angle at 973 K (700 °C) is approximately 97 deg, which indicates that aluminum does not wet alumina at aluminum casting temperatures. Thus, a priming height is required for aluminum to infiltrate a filter. Wetting in the Al-Al2O3 system increases with temperature.

  13. Spectrofluorimetric determination of trace aluminum in diluted hemodialysis solutions

    NASA Astrophysics Data System (ADS)

    Gündüz, S. Beniz; Küçükkolbaşý, Semahat; Atakol, Orhan; Kýlýç, Esma

    2005-03-01

    In this study, a spectrofluorimetric method has been developed for the determination of aluminum based on the formation of an aluminum complex with N, N'-disalicylidene-1,3-diamino-2-hydroxypropane (DSAHP). The most suitable pH, solvent medium, complex formation time, Schiff base concentration and temperature were determined. The excitation and emission wavelengths were 270 and 437 nm, respectively, in which the DSAHP-Al complex gave the maximum flurescence intensity at pH 3.0 and 6.0 in 50% dioxan-50% water medium. Under these conditions, calibration curves were obtained in three different linear limits, and was found that aluminum could be detected within the concentration limit of 0-10.0 μM and the lowest detection limit being 0.27 ng ml -1. The stochiometry of the DSAHP-Al complex was also determined spectrofluorimetrically under optimal conditions and the molar ratio of DSAHP-Al was calculated as 2:1. Using the developed method, aluminum was detected in hemodialysis solutions, and the results obtained were similar and comparable with those obtained using the method described in the British Pharmacopoeia within 95% confidence limits. This method can be used successfully for the routine determination of aluminum because it is quick, requires less amount of reactives, is sensitive, reliable and reproducible.

  14. Nanosized aluminum nitride hollow spheres formed through a self-templating solid-gas interface reaction

    SciTech Connect

    Zheng Jie Song Xubo; Zhang Yaohua; Li Yan; Li Xingguo; Pu Yikang

    2007-01-15

    Nanosized aluminum nitride hollow spheres were synthesized by simply heating aluminum nanoparticles in ammonia at 1000 deg. C. The as-synthesized sphere shells are polycrystalline with cavity diameters ranging from 15 to 100 nm and shell thickness from 5 to 15 nm. The formation mechanism can be explained by the nanoscale Kirkendall effect, which results from the difference in diffusion rates between aluminum and nitrogen. The Al nanoparticles served as both reactant and templates for the hollow sphere formation. The effects of precursor particle size and temperature were also investigated in terms of product morphology. Room temperature cathode luminescence spectrum of the nanosized hollow spheres showed a broad emission band centered at 415 nm, which is originated from oxygen related luminescence centers. The hollow structure survived a 4-h heat treatment at 1200 deg. C, exhibiting excellent thermal stability. - Graphical abstract: Nanosized aluminum nitride hollow spheres were synthesized by nitridation of aluminum nanoparticles at 1000 deg. C using ammonia.

  15. Unusual dicationic trimetallic aluminum chelates

    NASA Astrophysics Data System (ADS)

    Liu, S.; Munoz-Hernandez, M.-A.; Wei, P.; Atwood, D. A.

    2000-09-01

    The bimetallic compounds, L(AlMeCl) 2 with L=Salpen(tBu) ( N, N'-1,3-propylenenebis(3,5-di- tert-butylsalicylideneimine), Salben(tBu) ( N, N'-1,4-butylenebis(3,5-di- tert-butylsalicylideneimine)) and Salhen(tBu) ( N, N'-1,6 hexylenebis(3,5-di- tert-butylsalicylideneimine)) form the unusual trimetallic dicationic complexes, {[Salpen( tBu) ∗] 2(AlCl) 3]} 2+[GaCl 4] -[GaMe 2Cl 2] - ( 1), {[Salben( tBu) ∗] 2(AlCl) 3]} 2+[GaCl 4] -[GaMe 2Cl 2] - ( 2) and {[Salhen( tBu) ∗] 2(AlCl) 3]} 2+[GaCl 4] -[GaMe 2Cl 2] - ( 3) when combined with GaCl 3 in toluene. In their formation, the ligands of the compounds undergo a unique dealkylation reaction to lose one tBu group from each ligand (marked with an asterisk). These compounds are a new and unique class of aluminum cations. The compounds were characterized by Mp, analyses, IR, 1H NMR, and in the case of 1 and 2, by single-crystal X-ray diffractometry.

  16. Review paper: Role of aluminum in glass-ionomer dental cements and its biological effects.

    PubMed

    Nicholson, John W; Czarnecka, Beata

    2009-11-01

    The role of aluminum in glass-ionomers and resin-modified glass-ionomers for dentistry is reviewed. Aluminum is included in the glass component of these materials in the form of Al(2)O(3) to confer basicity on the glass and enable the glass to take part in the acid-base setting reactions. Results of studies of these reactions by FTIR and magic-angle spinning (MAS)-NMR spectroscopy are reported and the role of aluminum is discussed in detail. Aluminum has been shown to be present in the glasses in predominantly 4-coordination, as well as 5- and 6-coordination, and during setting a proportion of this is converted to 6-coordinate species within the matrix of the cement. Despite this, mature cements may contain detectable amounts of both 4- and 5-coordinate aluminum. Aluminum has been found to be leached from glass-ionomer cements, with greater amounts being released under acidic conditions. It may be associated with fluoride, with which it is known to complex strongly. Aluminum that enters the body via the gastro-intestinal tract is mainly excreted, and only about 1% ingested aluminum crosses the gut wall. Calculation shows that, if a glass-ionomer filling dissolved completely over 5 years, it would add only an extra 0.5% of the recommended maximum intake of aluminum to an adult patient. This leads to the conclusion that the release of aluminum from either type of glass-ionomer cement in the mouth poses a negligible health hazard.

  17. Fifth international fungus spore conference

    SciTech Connect

    Timberlake, W.E.

    1993-04-01

    This folio contains the proceedings of the Fifth International Fungal Spore Conference held August 17-21, 1991 at the Unicoi State Park at Helen, Georgia. The volume contains abstracts of each oral presentation as well as a collection of abstracts describing the poster sessions. Presentations were organized around the themes (1) Induction of Sporulation, (2) Nuclear Division, (3) Spore Formation, (4) Spore Release and Dispersal, and (4) Spore Germination.

  18. Use of Aluminum in Air-Brazing Aluminum Oxide

    SciTech Connect

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2004-06-01

    A commercial aluminum foil was used to braze alumina plates in air. Although the outer surface of the aluminum oxidizes in air, the majority of the aluminum underneath remains unoxidized during brazing, allowing the ceramic pieces to be joined together with adequate strength. In fact, the joint exhibits a modest increase in bend strength when exposed to air at 850ºC for a prolonged period of time. Joint strength testing and subsequent examination of the fracture surfaces of the joints indicate that the joints are inherently ductile, even after long-term, high-temperature air exposure.

  19. SIAM conference on applications of dynamical systems

    SciTech Connect

    Not Available

    1992-01-01

    A conference (Oct.15--19, 1992, Snowbird, Utah; sponsored by SIAM (Society for Industrial and Applied Mathematics) Activity Group on Dynamical Systems) was held that highlighted recent developments in applied dynamical systems. The main lectures and minisymposia covered theory about chaotic motion, applications in high energy physics and heart fibrillations, turbulent motion, Henon map and attractor, integrable problems in classical physics, pattern formation in chemical reactions, etc. The conference fostered an exchange between mathematicians working on theoretical issues of modern dynamical systems and applied scientists. This two-part document contains abstracts, conference program, and an author index.

  20. Aluminum anode for aluminum-air battery - Part I: Influence of aluminum purity

    NASA Astrophysics Data System (ADS)

    Cho, Young-Joo; Park, In-Jun; Lee, Hyeok-Jae; Kim, Jung-Gu

    2015-03-01

    2N5 commercial grade aluminum (99.5% purity) leads to the lower aluminum-air battery performances than 4N high pure grade aluminum (99.99% purity) due to impurities itself and formed impurity complex layer which contained Fe, Si, Cu and others. The impurity complex layer of 2N5 grade Al declines the battery voltage on standby status. It also depletes discharge current and battery efficiency at 1.0 V which is general operating voltage of aluminum-air battery. However, the impurity complex layer of 2N5 grade Al is dissolved with decreasing discharge voltage to 0.8 V. This phenomenon leads to improvement of discharge current density and battery efficiency by reducing self-corrosion reaction. This study demonstrates the possibility of use of 2N5 grade Al which is cheaper than 4N grade Al as the anode for aluminum-air battery.

  1. Dry machinability of aluminum alloys.

    SciTech Connect

    Shareef, I.; Natarajan, M.; Ajayi, O. O.; Energy Technology; Department of IMET

    2005-01-01

    Adverse effects of the use of cutting fluids and environmental concerns with regard to cutting fluid disposability is compelling industry to adopt Dry or near Dry Machining, with the aim of eliminating or significantly reducing the use of metal working fluids. Pending EPA regulations on metal cutting, dry machining is becoming a hot topic of research and investigation both in industry and federal research labs. Although the need for dry machining may be apparent, most of the manufacturers still consider dry machining to be impractical and even if possible, very expensive. This perception is mainly due to lack of appropriate cutting tools that can withstand intense heat and Built-up-Edge (BUE) formation during dry machining. The challenge of heat dissipation without coolant requires a completely different approach to tooling. Special tooling utilizing high-performance multi-layer, multi-component, heat resisting, low friction coatings could be a plausible answer to the challenge of dry machining. In pursuit of this goal Argonne National Labs has introduced Nano-crystalline near frictionless carbon (NFC) diamond like coatings (DLC), while industrial efforts have led to the introduction of composite coatings such as titanium aluminum nitride (TiAlN), tungsten carbide/carbon (WC/C) and others. Although, these coatings are considered to be very promising, they have not been tested either from tribological or from dry machining applications point of view. As such a research program in partnership with federal labs and industrial sponsors has started with the goal of exploring the feasibility of dry machining using the newly developed coatings such as Near Frictionless Carbon Coatings (NFC), Titanium Aluminum Nitride (TiAlN), and multi-layer multicomponent nano coatings such as TiAlCrYN and TiAlN/YN. Although various coatings are under investigation as part of the overall dry machinability program, this extended abstract deals with a systematic investigation of dry

  2. Aluminum plasmonic photocatalysis

    PubMed Central

    Hao, Qi; Wang, Chenxi; Huang, Hao; Li, Wan; Du, Deyang; Han, Di; Qiu, Teng; Chu, Paul K.

    2015-01-01

    The effectiveness of photocatalytic processes is dictated largely by plasmonic materials with the capability to enhance light absorption as well as the energy conversion efficiency. Herein, we demonstrate how to improve the plasmonic photocatalytic properties of TiO2/Al nano-void arrays by overlapping the localized surface plasmon resonance (LSPR) modes with the TiO2 band gap. The plasmonic TiO2/Al arrays exhibit superior photocatalytic activity boasting an enhancement of 7.2 folds. The underlying mechanisms concerning the radiative energy transfer and interface energy transfer processes are discussed. Both processes occur at the TiO2/Al interface and their contributions to photocatalysis are evaluated. The results are important to the optimization of aluminum plasmonic materials in photocatalytic applications. PMID:26497411

  3. Aluminum cluster reactions

    SciTech Connect

    Leuchtner, R.E.; Harms, A.C.; Castleman, A.W. Jr. )

    1991-01-15

    Aluminum clusters, both anion and cation, are produced using laser vaporization and reacted under thermal conditions with oxygen in a flow tube reactor. An etching reaction is observed and bimolecular rate constants are reported for Al{sup +}{sub {ital n}}, {ital n}=1--33, and Al{sup {minus}}{sub {ital n}}, {ital n}=5--37. For certain clusters, namely Al{sup +}{sub 7}, Al{sup {minus}}{sub 13}, and Al{sup {minus}}{sub 23}, no apparent reactivity is observed (they are found to be produced from larger species). Interestingly, these correspond to predicted jellium shell closings with 20, 40, and 70 electrons, respectively. Besides these exceptions, and a small odd/even alternation in reaction rates, the overall reactivity is relatively insensitive to cluster size, and is found to range between about 1 {times} 10{sup {minus}12} and 5 {times} 10{sup {minus}12} cm{sup 3}/s.

  4. Aluminum: Industry of the future

    SciTech Connect

    1998-11-01

    For over a century, the US aluminum industry has led the global market with advances in technology, product development, and marketing. Industry leaders recognize both the opportunities and challenges they face as they head into the 21st century, and that cooperative R and D is key to their success. In a unique partnership, aluminum industry leaders have teamed with the US Department of Energy`s Office of Industrial Technologies (OIT) to focus on innovative technologies that will help to strengthen the competitive position of the US aluminum industry and, at the same time, further important national goals. This industry-led partnership, the Aluminum Industry of the Future, promotes technologies that optimize the use of energy and materials in operations and reduce wastes and energy-related emissions. Led by The Aluminum Association, industry leaders began by developing a unified vision of future market, business, energy, and environmental goals. Their vision document, Partnerships for the Future, articulates a compelling vision for the next 20 years: to maintain and grow the aluminum industry through the manufacture and sale of competitively priced, socially desirable, and ecologically sustainable products. Continued global leadership in materials markets will require the combined resources of industry, universities, and government laboratories. By developing a unified vision, the aluminum industry has provided a framework for the next step in the Industries of the Future process, the development of a technology roadmap designed to facilitate cooperative R and D.

  5. Multidisciplinary OBGYN morbidity and mortality conference.

    PubMed

    Jackson, Jessica R; De Cesare, Julie Z

    2015-07-01

    Obstetrics and gynecology (OB-GYN) morbidity and mortality conferences allow for review of cases with poor or avoidable outcomes. Little data exist on standardized formats for presentation and evaluation. We designed a multidisciplinary morbidity and mortality conference. We formally evaluated resident performance using the milestones format, and evaluated resident understanding of case concepts with a pre- and post-conference survey. Our monthly conference was redesigned to incorporate the entire, residency program, OBGYN department members, nurses, midlevel providers, risk management, quality nurse director, and any additional staff who were involved in the case. Residents functioned as reviewers and presenters, and were then evaluated with a standard milestones-based evaluation by faculty members. Residents were also evaluated with a 10-point Likert scale for understanding of key case concepts, pre- and post-conference. Using a standardized format for presentation and evaluation improved resident presentation skills and ability to organize a vast amount of information from a chart into a valuable learning experience. Over a 6-month period, six cases were presented, and six actions were initiated for quality improvement. Resident understanding of concepts statistically improved after conference. M&M plays a crucial role not only in patient care, but also in resident education.

  6. Spray Rolling Aluminum Strip

    SciTech Connect

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  7. Aluminum toxicity. Hematological effects.

    PubMed

    Mahieu, S; del Carmen Contini, M; Gonzalez, M; Millen, N; Elias, M M

    2000-01-05

    Sequential effects of intoxication with aluminum hydroxide (Al) (80 mg/Kg body weight, i.p., three times a week), were studied on rats from weaning and up to 28 weeks. The study was carried out on hematological and iron metabolism-related parameters on peripheral blood, at the end of the 1st, 2nd, 3rd, 4th, 5th and 6th months of exposure. As it was described that hematotoxic effects of Al are mainly seen together with high levels of uremia, renal function was measured at the same periods. The animals treated developed a microcytosis and was accompanied by a decrease in mean corpuscular hemoglobin (MCH). Significantly lower red blood cell counts (RBC million/microl) were found in rats treated during the 1st month. These values matched those obtained for control rats during the 2nd month. From the 3rd month onwards, a significant increase was observed as compared to control groups, and the following values were obtained by the 6th month: (T) 10.0 +/- 0.3 versus (C) 8.7 +/- 0.2 (million/microl). Both MCH and mean corpuscular volume (MCV) were found to be significantly lower in groups treated from the 2nd month. At the end of the 6th month the following values were found: MCH (T) 13.3 +/- 0.1 versus (C) 16.9 +/- 0.3 (pg); MCV (T) 42.1 +/- 0.7 versus (C) 51.8 +/- 0.9 (fl). Al was found responsible for lower serum iron concentration levels and in the percentage of transferrin saturation. Thus, although microcytic anemia constitutes an evidence of chronic aluminum exposure, prolonged exposure could lead to a recovery of hematocrit and hemoglobin concentration values with an increase in red cell number. Nevertheless, both microcytosis and the decrease of MCH would persist. These modifications took place without changes being observed in the renal function during the observation period.

  8. Simulating weld-fusion boundary microstructures in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kostrivas, Anastasios D.; Lippold, John C.

    2004-02-01

    A fundamental study of weld-fusion boundary microstructure evolution in aluminum alloys was conducted in an effort to understand equiaxed grain zone formation and fusion boundary nucleation and growth phenomena. In addition to commercial aluminum alloys, experimental Mg-bearing alloys with Zr and Sc additions were studied along with the widely used Cu- and Licontaining alloy 2195-T8. This article describes work conducted to clarify the interrelation among composition, base metal substrate, and temperature as they relate to nucleation and growth phenomena at the fusion boundary.

  9. Cast joining between SiC and aluminum

    SciTech Connect

    Sato, Kenji; Kagawa, Yutaka

    1989-10-01

    A simple cast joining process between reaction-bonded SiC and aluminum has been investigated. Processing variables to obtain strong bonding strength were examined. Metallurgical observation showed that an SiC particle/Al-Si alloy composite layer was formed between RB-SiC and solidified aluminum, and Al4C3 was formed between the SiC particle, in the composite layer, and the Al-Si alloy matrix. Formation of Al4C3 and the composite layer was controlled by casting temperature and time, respectively. The bonding strength increased with decreasing of an unjoined area which formed at the joined surface.

  10. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  11. Non-Chromate Aluminum Pretreatments, Phase 2

    DTIC Science & Technology

    2004-09-01

    September 2004 78 ALUMINUM AL2024-T3 ALUMINUM AL7075 -T6 PNL ID 4 Control 5...ALUMINUM - AL2024-T3 192 ALUMINUM - AL7075 -T6 112 Table 5.13: AMCOM – NAVAIR PANEL TEST MATRIX OCTOBER 2003 NCAP Phase II Interim Report

  12. [Microbiological corrosion of aluminum alloys].

    PubMed

    Smirnov, V F; Belov, D V; Sokolova, T N; Kuzina, O V; Kartashov, V R

    2008-01-01

    Biological corrosion of ADO quality aluminum and aluminum-based construction materials (alloys V65, D16, and D16T) was studied. Thirteen microscopic fungus species and six bacterial species proved to be able to attack aluminum and its alloys. It was found that biocorrosion of metals by microscopic fungi and bacteria was mediated by certain exometabolites. Experiments on biocorrosion of the materials by the microscopic fungus Alternaria alternata, the most active biodegrader, demonstrated that the micromycete attack started with the appearance of exudate with pH 8-9 on end faces of the samples.

  13. 75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... Employment and Training Administration Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood... Aluminum Fabricated Products, LLC, Kaiser Aluminum-Greenwood Forge Division, including on- site leased... are engaged in the production of aluminum alloy forgings. Information shows that on July 28, 2010...

  14. Conference Abstracts: AEDS '82.

    ERIC Educational Resources Information Center

    Journal of Computers in Mathematics and Science Teaching, 1982

    1982-01-01

    Abstracts from nine selected papers presented at the 1982 Association for Educational Data Systems (AEDS) conference are provided. Copies of conference proceedings may be obtained for fifteen dollars from the Association. (MP)

  15. Fundamental studies on electrochemical production of dendrite-free aluminum and titanium-aluminum alloys

    NASA Astrophysics Data System (ADS)

    Pradhan, Debabrata

    A novel dendrite-free electrorefining of aluminum scrap was investigated by using AlCl3-1-Ethyl-3-methyl-imidazolium chloride (EMIC) ionic liquid electrolyte. Electrodeposition of aluminum were conducted on copper/aluminum cathodes at voltage of 1.5 V, temperatures (50-110°C), stirring rate (0-120 rpm), molar ratio (MR) of AlCl3:EMIC (1.25-2.0) and electrode surface modification (modified/unmodified). The study was focused to investigate the effect of process variables on deposit morphology, cathode current density and their role in production of dendrite-free aluminum. The deposits were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Modified electrodes and stirring rate (60 rpm) eliminate dendritic deposition by reducing cathode overpotential below critical overpotential (etacrt≈ -0.54 V) for dendrite formation. Pure aluminum (>99%) was deposited with current efficiency of 84-99%. Chronoamperometry study was conducted using AlCl3-EMIC and AlCl3-1-Butyl-3-methyl-imidazolium chloride (BMIC) (MR = 1.65:1) at 90°C to understand the mechanism of aluminum electrodeposition and find out diffusion parameter of electroactive species Al2C 7-. It was concluded that electrodeposition of aluminum is a diffusion controlled instantaneous nucleation process and diffusion coefficient of Al2C7- was found to be 5.2-6.9 x 10-11 m2/s and 2.2 x 10-11 m2/s for AlCl3-EMIC and AlCl3-BMIC, respectively. A novel production route of Ti-Al alloys was investigated using AlCl 3-BMIC-TiCl4 (MR = 2:1:0.019) and AlCl3-BMIC (MR = 2:1) electrolytes at constant voltages of 1.5-3.0 V and temperatures (70-125°C). Ti sheet was used as anode and cathode. Characterization of electrodeposited Ti-Al alloys was carried out using SEM, EDS, XRD and inductively coupled plasma-optical emission spectrometer (ICP-OES). Effect of voltage and temperature on cathode current density, current efficiency, composition and morphology of Ti

  16. Aluminum nanoparticles burning - still a puzzle?

    NASA Astrophysics Data System (ADS)

    Gromov, A. A.; Popenko, E. M.

    2009-09-01

    The experimental data on the aluminum nanopowders (nAl) combustion in oxidizing media (air, propellants AP/HTPB/Al/HMX, and energetic compositions) assuming the phenomenon of nitrides formation with the high yield is generalized. In the present work, the nAl produced by electrical explosion of wires was studied. The temperature, burning rate, and radiation were measured at combustion and the actual burning process was recorded by a videocamera. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and chemical analysis were performed on the both initial powders and final condensed products. It was experimentally proved that the combustion process of aluminum nanoparticles was two staged independently of burning conditions in nitrogen-containing media. The formation of nitrides in presence of molecular nitrogen is the determining stage in the particles combustion. A qualitative discussion is given on the kinetic limitation for AlN (AlON) oxidation due to rapid condensation and encapsulation of solid AlN (AlON).

  17. Fracture mechanisms of a 2124 aluminum

    NASA Astrophysics Data System (ADS)

    Kim, Young-Hwan; Lee, Sunghak; Kim, Nack J.

    1992-09-01

    This study was aimed at investigating the effects of microstructure on the fracture behavior of a 2124 aluminum composite reinforced with SiC whiskers. Particular emphasis was placed on the role of matrix intermetallic particles, inhomogeneous distribution of whiskers, and whisker breakage in the fracture process. Various tests were conducted on the composite to identify the micromechanical processes that were involved in microvoid or microcrack formation. Detailed microstructural analyses showed that the aluminum matrix contained a significant amount of coarse manganese-containing particles of various sizes which could have been formed during composite processing. In situ scanning electron microscope (SEM) fracture study of the crack initiation and propagation processes clearly showed that these coarse particles fractured prior to matrix/whisker decohesion or whisker breakage, suggesting that the manganese-containing par- ticles significantly accelerated crack initiation in the 2124 Al-SiCw composite. For a better ma- trix alloy for use in the composite, it is suggested that microalloying elements must be monitored to prevent the formation of the coarse intermetallic particles.

  18. Parent Conferences. Beginnings Workshop.

    ERIC Educational Resources Information Center

    Duffy, Roslyn; And Others

    1997-01-01

    Presents six workshop sessions on parent conferences: (1) "Parents' Perspectives on Conferencing" (R. Duffy); (2) "Three Way Conferences" (G. Zeller); (3) "Conferencing with Parents of Infants" (K. Albrecht); (4) "Conferencing with Parents of School-Agers" (L. G. Miller); (5) "Cross Cultural Conferences" (J. Gonzalez-Mena); and (6) "Working with…

  19. EDITORIAL: Conference program

    NASA Astrophysics Data System (ADS)

    2006-04-01

    Some of the papers and talks given at the conference have not been published in this volume of Journal of Physics: Conference Series. The attached PDF file lists the full conference program and indicates (with an asterisk) those papers or talks which are not present in this volume.

  20. The General Conference Mennonites.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    General Conference Mennonites and Old Order Amish are compared and contrasted in the areas of physical appearance, religious beliefs, formal education, methods of farming, and home settings. General Conference Mennonites and Amish differ in physical appearance and especially in dress. The General Conference Mennonite men and women dress the same…

  1. Youth Conference Handbook.

    ERIC Educational Resources Information Center

    Brown, Brenda H.

    This handbook is designed to provide practical aid to those who have charge of the planning and organization of a youth conference, Defined as a conference to provide practical information as well as information about possible responsibilities, risks, and consequences of actions, related to the chosen conference topic. Suggestions are given for…

  2. Carbide coated fibers in graphite-aluminum composites

    NASA Technical Reports Server (NTRS)

    Imprescia, R. J.; Levinson, L. S.; Reiswig, R. D.; Wallace, T. C.; Williams, J. M.

    1975-01-01

    The study of protective-coupling layers of refractory metal carbides on the graphite fibers prior to their incorporation into composites is presented. Such layers should be directly wettable by liquid aluminum and should act as diffusion barriers to prevent the formation of aluminum carbide. Chemical vapor deposition was used to uniformly deposit thin, smooth, continuous coats of ZrC on the carbon fibers of tows derived from both rayon and polyacrylonitrile. A wet chemical coating of the fibers, followed by high-temperature treatment, was used, and showed promise as an alternative coating method. Experiments were performed to demonstrate the ability of aluminum alloys to wet carbide surfaces. Titanium carbide, zirconium carbide and carbide-coated graphite surfaces were successfully wetted. Results indicate that initial attempts to wet surfaces of ZrC-coated carbon fibers appear successful.

  3. Local vaccine site reactions and contact allergy to aluminum.

    PubMed

    Beveridge, Mara G; Polcari, Ingrid C; Burns, Jennifer L; Adler, Amos; Hendrickson, Barbara; Stein, Sarah L

    2012-01-01

    Childhood vaccines are a routine part of pediatric care in the United States; clinicians must be able to recognize and interpret associated localized adverse reactions. Redness and induration at the site of injection are commonly reported and are considered to be the result of local inflammation or hematoma formation, although other atypical reactions can occur. We report the case of a 6-month-old infant who developed subcutaneous nodules at the sites of his 4- and 6-month Pentacel (DTaP/Hib/IPV, diphtheria, tetanus, acellular pertussis, Haemophilus b conjugate, and inactivated poliovirus vaccine) and 6-month Prevnar (heptavalent pneumococcal vaccine) injections. Infectious disease and immunodeficiency examinations were unremarkable. Aluminum contact allergy was considered, and contact allergy testing confirmed sensitivity to aluminum. Although rare, aluminum contact allergy after routine immunization can occur and should be considered in the differential diagnosis of persistent subcutaneous nodules after vaccination. © 2011 Wiley Periodicals, Inc.

  4. A Case of Recurrent Renal Aluminum Hydroxide Stone

    PubMed Central

    Cakıroglu, Basri; Dogan, Akif Nuri; Tas, Tuncay; Gozukucuk, Ramazan; Uyanik, Bekir Sami

    2014-01-01

    Renal stone disease is characterized by the differences depending on the age, gender, and the geographic location of the patients. Seventy-five percent of the renal stone components is the calcium (Ca). The most common type of the stones is the Ca oxalate stones, while Ca phosphate, uric acid, struvite, and sistine stones are more rarely reported. Other than these types, triamterene, adenosine, silica, indinavir, and ephedrine stones are also reported in the literature as case reports. However, to the best of our knowledge, aluminum hydroxide stones was not reported reported before. Herein we will report a 38-years-old woman with the history of recurrent renal colic disease whose renal stone was determined as aluminum hydroxide stone in type. Aluminum mineral may be considered in the formation of kidney stones as it is widely used in the field of healthcare and cosmetics. PMID:25013740

  5. Structure and properties of porous ceramics obtained from aluminum hydroxide

    NASA Astrophysics Data System (ADS)

    Levkov, R.; Kulkov, S.

    2016-08-01

    In this paper the study of porous ceramics obtained from aluminum hydroxide with gibbsite modification is presented. The dependence of porosity and mechanical characteristics of the material sintered at different temperatures was studied. It was shown that compressive strength of alumina ceramics increases by 40 times with decreasing the pore volume from 65 to 15%. It was shown that aluminum hydroxide may be used for pore formation and pore volume in the sintered ceramics can be controlled by varying the aluminum hydroxide concentration and sintering temperature. Based on these results one can conclude that the obtained structure is very close to inorganic bone matrix and can be used as promising material for bone implants production.

  6. Electrolyte treatment for aluminum reduction

    DOEpatents

    Brown, Craig W.; Brooks, Richard J.; Frizzle, Patrick B.; Juric, Drago D.

    2002-01-01

    A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF.sub.3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

  7. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  8. Chrome - Free Aluminum Coating System

    NASA Technical Reports Server (NTRS)

    Bailey, John H.; Gugel, Jeffrey D.

    2010-01-01

    This slide presentation concerns the program to qualify a chrome free coating for aluminum. The program was required due to findings by OSHA and EPA, that hexavalent chromium, used to mitigate corrosion in aerospace aluminum alloys, poses hazards for personnel. This qualification consisted of over 4,000 tests. The tests revealed that a move away from Cr+6, required a system rather than individual components and that the maximum corrosion protection required pretreatment, primer and topcoat.

  9. Ballistic Evaluation of 7085 Aluminum

    DTIC Science & Technology

    2012-03-01

    tempers of aluminum alloy (AA) 7085 produced by Alcoa . The tempers included a high-strength variant, 7085-T7E01, for utilization as an appliqué against... Alcoa ) for providing the aluminum plates for testing and Donald Little (U.S. Army Research Laboratory, Armor Mechanisms Branch), Phil Davis...investigated for armor utilization by Alcoa . Two tempers were developed, a high-strength variant, 7085-T7E01, for utilization as an appliqué against

  10. Ballistic Evaluation of 6055 Aluminum

    DTIC Science & Technology

    2015-09-01

    alloy (AA) 6055-T651 produced by Alcoa as part of a Defense Acquisition Challenge Program. Ballistic evaluation was performed using armor-piercing...compared to other ballistic-grade aluminum alloys , namely AA6061 and AA7039. The results of these experiments were used to derive the acceptance tables...as those of M2 Bradley Infantry Fighting Vehicles. Also in 2012, the Aluminum Association assigned a new 6XXX-series alloy designation to Alcoa for

  11. Ballistic Evaluation of 2060 Aluminum

    DTIC Science & Technology

    2016-05-24

    aluminum alloy (AA) 2060-T8 produced by Alcoa as part of a Defense Acquisition Challenge Program. Ballistic evaluation was performed using armor-piercing...included in the updated military specification MIL-DTL-32341A (MR). 15. SUBJECT TERMS aluminum, armor, V50, 2060, 6055, Defense Acquisition Challenge ...BLANK. Approved for public release; distribution is unlimited. 1 1. Introduction In 2012 a Defense Acquisition Challenge (DAC) program proposal

  12. Abnormal behavior of silica doped with small amounts of aluminum

    PubMed Central

    Liu, Jinling; Wang, Yiguang; An, Linan

    2016-01-01

    Silica is the most abundant mineral in the crust of the Earth. It has been demonstrated that the aluminum concentration in silica plays a key role in determining many properties of silica-based components. Although the alumina-silica system has been intensely studied, the effect of very small amounts of aluminum on the structure and properties of silica remains unclear. We report results of first principles calculations showing that small amounts of aluminum could be metastable when located in the center of Si-O rings without breaking the silica network. In contrast, higher aluminum contents will result in the destruction of the Si-O bonds, leading to the formation of triclusters and a 4-, 5-, and 6-fold Al-O coordination, as observed in previous studies. Based on the silica structure obtained through geometric optimization, the properties of silica doped with small amounts of aluminum were calculated. The results can account for many ‘abnormal’ phenomena experimentally observed. The results benefit most areas such as geosciences, microelectronics, glass industry, and ceramic materials. PMID:27752133

  13. Abnormal behavior of silica doped with small amounts of aluminum

    NASA Astrophysics Data System (ADS)

    Liu, Jinling; Wang, Yiguang; An, Linan

    2016-10-01

    Silica is the most abundant mineral in the crust of the Earth. It has been demonstrated that the aluminum concentration in silica plays a key role in determining many properties of silica-based components. Although the alumina-silica system has been intensely studied, the effect of very small amounts of aluminum on the structure and properties of silica remains unclear. We report results of first principles calculations showing that small amounts of aluminum could be metastable when located in the center of Si-O rings without breaking the silica network. In contrast, higher aluminum contents will result in the destruction of the Si-O bonds, leading to the formation of triclusters and a 4-, 5-, and 6-fold Al-O coordination, as observed in previous studies. Based on the silica structure obtained through geometric optimization, the properties of silica doped with small amounts of aluminum were calculated. The results can account for many ‘abnormal’ phenomena experimentally observed. The results benefit most areas such as geosciences, microelectronics, glass industry, and ceramic materials.

  14. A Virtual Aluminum Reduction Cell

    NASA Astrophysics Data System (ADS)

    Zhang, Hongliang; Zhou, Chenn Q.; Wu, Bing; Li, Jie

    2013-11-01

    The most important component in the aluminum industry is the aluminum reduction cell; it has received considerable interests and resources to conduct research to improve its productivity and energy efficiency. The current study focused on the integration of numerical simulation data and virtual reality technology to create a scientifically and practically realistic virtual aluminum reduction cell by presenting complex cell structures and physical-chemical phenomena. The multiphysical field simulation models were first built and solved in ANSYS software (ANSYS Inc., Canonsburg, PA, USA). Then, the methodology of combining the simulation results with virtual reality was introduced, and a virtual aluminum reduction cell was created. The demonstration showed that a computer-based world could be created in which people who are not analysis experts can see the detailed cell structure in a context that they can understand easily. With the application of the virtual aluminum reduction cell, even people who are familiar with aluminum reduction cell operations can gain insights that make it possible to understand the root causes of observed problems and plan design changes in much less time.

  15. Neurobehavioral performance in aluminum welders.

    PubMed

    Bast-Pettersen, R; Skaug, V; Ellingsen, D; Thomassen, Y

    2000-02-01

    Twenty aluminum welders (mean age 33 years; range 21-52), who had been exposed to aluminum for an average of 8.1 years (range 2-21), were tested for tremor and reaction time and screened for neuropsychiatric symptoms in a cross-sectional study. The welders' median urinary aluminum concentration was 1.5 micromol/L (range 0. 7-4.8). Aluminum in air, measured inside the respiratory protection, was 0.9 mg/m(3) (range 0.6-3.8). The welders were compared with twenty construction workers matched for age. Welders reported more symptoms than referents did (median 2 vs. 1; P=0.047). Although the welders as a group performed better than the referents on a tremor test, years of exposure, but not age, was predictive of poorer performance. The welders' reaction times were rapid by clinical standards (mean simple reaction time (SRT): 221 milliseconds; mean continuous performance test (CPT): 364 milliseconds). Although, as a group, they performed better than the referents, there was a statistically significant relation between longer reaction times and aluminum in air (air-Al). The relations between hand steadiness and years exposed, and between reaction time and air-Al, could indicate slight effects from exposure to aluminum. The possibility of selection of workers with high manual skills into welding work and a possible job-related training effect, might partly serve to explain the good performance among the welders. Copyright 2000 Wiley-Liss, Inc.

  16. Optomechanics of Single Aluminum Nanodisks.

    PubMed

    Su, Man-Nung; Dongare, Pratiksha D; Chakraborty, Debadi; Zhang, Yue; Yi, Chongyue; Wen, Fangfang; Chang, Wei-Shun; Nordlander, Peter; Sader, John E; Halas, Naomi J; Link, Stephan

    2017-04-12

    Aluminum nanostructures support tunable surface plasmon resonances and have become an alternative to gold nanoparticles. Whereas gold is the most-studied plasmonic material, aluminum has the advantage of high earth abundance and hence low cost. In addition to understanding the size and shape tunability of the plasmon resonance, the fundamental relaxation processes in aluminum nanostructures after photoexcitation must be understood to take full advantage of applications such as photocatalysis and photodetection. In this work, we investigate the relaxation following ultrafast pulsed excitation and the launching of acoustic vibrations in individual aluminum nanodisks, using single-particle transient extinction spectroscopy. We find that the transient extinction signal can be assigned to a thermal relaxation of the photoexcited electrons and phonons. The ultrafast heating-induced launching of in-plane acoustic vibrations reveals moderate binding to the glass substrate and is affected by the native aluminum oxide layer. Finally, we compare the behavior of aluminum nanodisks to that of similarly prepared and sized gold nanodisks.

  17. Conference report: formulating better medicines for children: 4th European Paediatric Formulation Initiative conference.

    PubMed

    Walsh, Jennifer; Mills, Simon

    2013-01-01

    The fourth annual European Paediatric Formulation Initiative (EuPFI) conference on Formulating Better Medicines for Children was held on 19-20 September 2012 at the Institute of Molecular Genetics Congress Centre, Prague, Czech Republic. The 2-day conference concentrated on the latest advances, challenges and opportunities for developing medicinal products and administration devices for pediatric use, both from European and US perspectives. It was aimed specifically at providing exposure to emerging practical applications, and for illustrating remedies utilized by pediatric drug-development teams to overcome hurdles faced in developing medicines for pediatric patients. The conference format included plenary talks, focus sessions on each of the EuPFI work streams (extemporaneous preparations, excipients, pediatric administration devices, taste masking and taste assessment, age-appropriate formulations), case studies, soapbox sessions and a parallel poster display. This conference report summarizes the keynote lectures and also gives a flavor of other presentations and posters from the conference.

  18. Hydrogen partitioning in pure cast aluminum as determined by dynamic evolution rate measurements

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Peterson, D. T.; Schmidt, F. A.

    1981-01-01

    Hydrogen in pure aluminum can be found in two different states. One is related to a presence in gas-filled pores, while the other state involves the formation of a solid solution between hydrogen and aluminum. The considered investigation is concerned with the distribution of the hydrogen between various states. A dynamic technique is employed to measure the evolution of hydrogen from commercially available samples of polycrystalline pure aluminum under ultrahigh vacuum conditions. The obtained data are compared with the results of a statistical analysis concerning the porosity in the cast aluminum. It was found that more than 99 pct of the hydrogen in the aluminum is located in large pores. Less than 1 pct of the hydrogen is partitioned between the solid solution and the small pores.

  19. Synthesis and properties of aluminum-based composite materials for high operating temperatures

    NASA Astrophysics Data System (ADS)

    Vorozhtsov, Sergey; Khrustalyov, Anton; Kulkov, Sergey

    2016-11-01

    Aluminum-based composite materials reinforced with ceramic particles are of great practical interest due to their potentially high physical and mechanical properties. In this work, Al-Al4C3 composites are obtained by a hot-pressing method. Introduction of nanodiamonds into aluminum nanopowder in the amount 10 wt % leads to the formation of 15 wt % of aluminum carbide during hot pressing. It is found that composite materials with the diamond content of 10 wt % in the initial powder mixture have the microhardness 150 HV whilst the similarly hot-pressed aluminum powder without reinforcing particles shows a hardness of 75 HV. The mechanical properties of an Al-Al4C3 composite material at elevated test temperatures exceed those of commercial casting aluminum alloys.

  20. Hydrogen partitioning in pure cast aluminum as determined by dynamic evolution rate measurements

    NASA Technical Reports Server (NTRS)

    Outlaw, R. A.; Peterson, D. T.; Schmidt, F. A.

    1981-01-01

    Hydrogen in pure aluminum can be found in two different states. One is related to a presence in gas-filled pores, while the other state involves the formation of a solid solution between hydrogen and aluminum. The considered investigation is concerned with the distribution of the hydrogen between various states. A dynamic technique is employed to measure the evolution of hydrogen from commercially available samples of polycrystalline pure aluminum under ultrahigh vacuum conditions. The obtained data are compared with the results of a statistical analysis concerning the porosity in the cast aluminum. It was found that more than 99 pct of the hydrogen in the aluminum is located in large pores. Less than 1 pct of the hydrogen is partitioned between the solid solution and the small pores.

  1. Nanopore gradients on porous aluminum oxide generated by nonuniform anodization of aluminum.

    PubMed

    Kant, Krishna; Low, Suet P; Marshal, Asif; Shapter, Joseph G; Losic, Dusan

    2010-12-01

    A method for surface engineering of structural gradients with nanopore topography using the self-ordering process based on electrochemical anodization of aluminum is described. A distinct anodization condition with an asymmetrically distributed electric field at the electrolyte/aluminum interface is created by nonparallel arrangement between electrodes (tilted by 45°) in an electrochemical cell. The anodic aluminum oxide (AAO) porous surfaces with ordered nanopore structures with gradual and continuous change of pore diameters from 80 to 300 nm across an area of 0.5-1 cm were fabricated by this anodization using two common electrolytes, oxalic acid (0.3 M) and phosphoric acid (0.3 M). The formation of pore gradients of AAO is explained by asymmetric and gradual distribution of the current density and temperature variation generated on the surface of Al during the anodization process. Optical and wetting gradients of prepared pore structures were confirmed by reflective interferometric spectroscopy and contact angle measurements showing the ability of this method to generate porous surfaces with multifunctional gradients (structural, optical, wetting). The study of influence of pore structures on cell growth using the culture of neuroblastoma cells reveals biological relevance of nanopore gradients and the potential to be applied as the platform for spatially controllable cell growth and cell differentiation.

  2. Commonwealth Aluminum: Manufacturer Conducts Plant-Wide Energy Assessments at Two Aluminum Sheet Production Operations;

    SciTech Connect

    Not Available

    2006-04-01

    DOE Industrial Technologies Program case study describes the savings possible if Commonwealth Aluminum (now Aleris Rolled Products) makes improvements noted in energy assessments at two aluminum mills.

  3. Commonwealth Aluminum: Manufacturer Conducts Plant-Wide Energy Assessments at Two Aluminum Sheet Production Operations

    SciTech Connect

    2006-04-01

    DOE Industrial Technologies Program case study describes the savings possible if Commonwealth Aluminum (now Aleris Rolled Products) makes improvements noted in energy assessments at two aluminum mills.

  4. Synthesis of aluminum hydrazides by hydroalumination of 2,3-diazabutadienes--formation of an Al4(N2)3 cage compound and an Al3(N2)3 macrocyclic ligand.

    PubMed

    Uhl, W; Molter, J; Neumüller, B

    2001-04-01

    Treatment of 1,1,4,4-tetramethyl-2,3-diazabutadiene with the alane adduct [AlH3(NMe2Et)] yielded the hydrazine derivative (AlH2)2-(AlH)2(N2iPr2)3 (1) by the hydroalumination of both C N double bonds. Compound 1 has a complicated cage structure formed by three hydrazido groups and four aluminium atoms. As a particularly interesting structural motif it contains a N-N group side-on-coordinated to one aluminium atom through its lone pairs of electrons. Sublimation of 1 gave a heterocubane-type compound (HAlNiPr)4 (2) by the complete cleavage of all N-N bonds, one face of which is bridged by weakly coordinated diisopropyldiazene with a N-N double bond. Repeated sublimation gave the pure, unsupported heterocubane molecule 3. Heating of the rough product of the reaction of alane and diazabutadiene to 90 degrees C in a closed vessel yielded another product Al(AlH2)3(N2iPr2)3 (4), which contains a cyclic chelating ligand formed by three hydrazido groups and three aluminium atoms. This heterocycle coordinates a fourth aluminum atom in the molecular center by close contacts to all six nitrogen atoms. A strongly flattened, distorted octahedral coordination sphere results for the inner metal atom.

  5. Views from the 1995 ECC conference

    SciTech Connect

    Lowry, J.C.; Haegelin, J.K.; Underwood, J.K.

    1995-12-01

    The Engineering and Construction Contracting Division (ECC) of the AIChE held its 27th Annual Conference in Scottsdale, Arizona, Sept. 7--8, 1995. Each year the conference is attended by management representatives from manufacturers, producers, engineering and construction contractors, consultants and major equipment suppliers. The 1995 conference theme was, Applying Advanced Methodology to Improve Project Execution. What were the issues and recommendations resulting from the conference? Here are the composite results from the annual workshops, as well as some perspectives from three selected participants. The paper discusses modularization in the process industry, innovative construction practices, creation and use of 3-D models for the plant`s life cycle, alliances and pay-for-performance contracting, and new workshop formats, and ends with general views from selected participants.

  6. Reduction of Oxidative Melt Loss of Aluminum and Its Alloys

    SciTech Connect

    Dr. Subodh K. Das; Shridas Ningileri

    2006-03-17

    This project led to an improved understanding of the mechanisms of dross formation. The microstructural evolution in industrial dross samples was determined. Results suggested that dross that forms in layers with structure and composition determined by the local magnesium concentration alone. This finding is supported by fundamental studies of molten metal surfaces. X-ray photoelectron spectroscopy data revealed that only magnesium segregates to the molten aluminum alloy surface and reacts to form a growing oxide layer. X-ray diffraction techniques that were using to investigate an oxidizing molten aluminum alloy surface confirmed for the first time that magnesium oxide is the initial crystalline phase that forms during metal oxidation. The analytical techniques developed in this project are now available to investigate other molten metal surfaces. Based on the improved understanding of dross initiation, formation and growth, technology was developed to minimize melt loss. The concept is based on covering the molten metal surface with a reusable physical barrier. Tests in a laboratory-scale reverberatory furnace confirmed the results of bench-scale tests. The main highlights of the work done include: A clear understanding of the kinetics of dross formation and the effect of different alloying elements on dross formation was obtained. It was determined that the dross evolves in similar ways regardless of the aluminum alloy being melted and the results showed that amorphous aluminum nitride forms first, followed by amorphous magnesium oxide and crystalline magnesium oxide in all alloys that contain magnesium. Evaluation of the molten aluminum alloy surface during melting and holding indicated that magnesium oxide is the first crystalline phase to form during oxidation of a clean aluminum alloy surface. Based on dross evaluation and melt tests it became clear that the major contributing factor to aluminum alloy dross was in the alloys with Mg content. Mg was

  7. Low-aluminum content iron-aluminum alloys

    SciTech Connect

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.

    1995-06-01

    The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10 and iron = 83.71. The ignots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot-worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

  8. Terbium photoluminescence in yttrium aluminum garnet xerogels

    SciTech Connect

    Maliarevich, G. K.; Gaponenko, N. V. Mudryi, A. V.; Drozdov, Yu. N.; Stepikhova, M. V.; Stepanova, E. A.

    2009-02-15

    Based on a colloidal solution containing terbium, yttrium, and aluminum metal ions, a powder was synthesized and films of terbium-doped yttrium aluminum garnet Tb{sub 0.15}Y{sub 2.85}Al{sub 5}O{sub 12} were grown on single-crystal silicon and porous anodic alumina. Annealing of the sample in a temperature range from 200-1100 deg. C results in an increase in the photoluminescence intensity in the wavelength range from 480-640 nm, which is caused by Tb{sup 3+} ion intra-atomic transitions {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub j} (j = 3, 4, 5, 6). Annealing at 900 deg. C and higher temperatures gives rise to low-intensity photoluminescence bands in the region of 667 and 681 nm, which correspond to transitions {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub 0}, {sup 5}D{sub 4}{sup {yields}}{sup 7}F{sub 1}, and room-temperature Stark term splitting, which suggests the existence of a crystalline environment of Tb{sup 3+} ions. The FWHM of spectral lines in the region of 543 nm decreases from {approx}10 to {approx}(2-3) nm as the xerogel annealing temperature is increased from 700 to 900 deg. C and higher. Three bands with maxima at 280, 330, and 376 nm, which correspond to Tb{sup 3+} ion transitions {sup 7}F{sub 6}{sup {yields}}{sup 5}I{sub 8}, {sup 5}L{sub 6}, {sup 5}G{sub 6}, {sup 5}D{sub 3}, are observed in the photoluminescence excitation spectra of the studied structures for the emission wavelength at 543 nm. X-ray diffraction detected the formation of a crystalline phase for a terbium-doped yttrium aluminum garnet powder after annealing at 1100 deg. C.

  9. Aluminum-dependent regulation of intracellular silicon in the aquatic invertebrate Lymnaea stagnalis

    PubMed Central

    Desouky, Mahmoud; Jugdaohsingh, Ravin; McCrohan, Catherine R.; White, Keith N.; Powell, Jonathan J.

    2002-01-01

    Silicon is essential for some plants, diatoms, and sponges but, in higher animals, its endogenous regulation has not been demonstrated. Silicate ions may be natural ligands for aluminum and here we show that, in the freshwater snail (Lymnaea stagnalis), intracellular silicon seems specifically up-regulated in response to sublethal aluminum exposure. X-ray microanalysis showed that exposure of snails to low levels of aluminum led to its accumulation in lysosomal granules, accompanied by marked up-regulation of silicon. Increased lysosomal levels of silicon were a specific response to aluminum because cadmium and zinc had no such effect. Furthermore, intra-lysosomal sulfur from metallothionein and other sulfur-containing ligands was increased after exposure to cadmium and zinc but not aluminum. To ensure that these findings indicated a specific in vivo response, and not ex vivo formation of hydroxy-aluminosilicates (HAS) from added aluminum (555 μg/liter) and water-borne silicon (43 μg/liter), two further studies were undertaken. In a ligand competition assay the lability of aluminum (527 μg/liter) was completely unaffected by the presence of silicon (46 μg/liter), suggesting the absence of HAS. In addition, exogenous silicon (6.5 mg/liter), added to the water column to promote formation of HAS, caused a decrease in lysosomal aluminum accumulation, showing that uptake of HAS would not explain the loading of aluminum into lysosomal granules. These findings, and arguments on the stability, lability, and kinetics of aluminum–silicate interactions, suggest that a silicon-specific mechanism exists for the in vivo detoxification of aluminum, which provides regulatory evidence of silicon in a multicellular organism. PMID:11891333

  10. Shuttle Redesigned Solid Rocket Motor aluminum oxide investigations

    NASA Astrophysics Data System (ADS)

    Blomshield, Fred S.; Kraeutle, Karl J.; Stalnaker, Richard A.

    1994-10-01

    During the launch of STS-54, a 15 psi pressure blip was observed in the ballistic pressure trace of one of the two Space Shuttle Redesigned Solid Rocket Motors (RSRM). One possible scenario for the observed pressure increase deals with aluminum oxide slag formation in the RSRM. The purpose of this investigation was to examine changes which may have occurred in the aluminum oxide formation in shuttle solid propellant due to changes in the ammonium perchlorate. Aluminum oxide formation from three propellants, all having the same formulation, but containing ammonium perchlorate from different manufacturers, will be compared. Three methods have been used to look for possible differences among the propellants. The first method was to examine window bomb movies of the propellants burning at 100, 300 and 600 psia. The motor operating pressure during the pressure blip was around 600 psia. The second method used small samples of propellant which were fired in a combustion bomb which quenched the burning aluminum particles soon after they left the propellant surface. The bomb was fired in both argon and Nitrogen atmospheres at various pressures. Products from this device were examined by optical microscopy. The third method used larger propellant samples fired into a particle collection device which allowed the aluminum to react and combust more completely. This device was pressurized with Nitrogen to motor operating pressures. The collected products were subdivided into size fractions by screening and sedimentation and analyzed optically with an optical microscope. the results from all three methods indicate very small changes in the size distribution of combustion products.

  11. Association mapping provides insights into the origin and the fine structure of the sorghum aluminum tolerance locus, AltSB

    USDA-ARS?s Scientific Manuscript database

    Root damage caused by aluminum (Al) toxicity is a major cause of grain yield reduction on acid soils, which are prevalent in tropical and subtropical regions of the world where food security is most tenuous. In sorghum, Al tolerance is conferred by SbMATE, an Al-activated root citrate efflux transpo...

  12. Weld Repair of Thin Aluminum Sheet

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Mitchell, M. J.

    1986-01-01

    Weld repairing of thin aluminum sheets now possible, using niobium shield and copper heat sinks. Refractory niobium shield protects aluminum adjacent to hole, while copper heat sinks help conduct heat away from repair site. Technique limits tungsten/inert-gas (TIG) welding bombardment zone to melt area, leaving surrounding areas around weld unaffected. Used successfully to repair aluminum cold plates on Space Shuttle, Commercial applications, especially in sealing fractures, dents, and holes in thin aluminum face sheets or clad brazing sheet in cold plates, heat exchangers, coolers, and Solar panels. While particularly suited to thin aluminum sheet, this process also used in thicker aluminum material to prevent surface damage near weld area.

  13. Aluminum Metal Matrix Composites

    SciTech Connect

    Hunt, Warren; Herling, Darrell R.

    2004-02-01

    Metal matrix composites comprise a relatively wide range of materials defined by the metal matrix, reinforcement type, and reinforcement geometry. In the area of the matrix, most metallic systems have been explored for use in metal matrix composites, including Al, Be, Mg, Ti, Fe, Ni, Co, and Ag. By far, the largest usage is in aluminum matrix composites. From a reinforcement perspective, the materials used are typically ceramics since they provide a very desirable combination of stiffness, strength, and relatively low density. Candidate reinforcement materials include SiC, Al2O3, B4C, TiC, TiB2, graphite, and a number of other ceramics. In addition, there has been work on metallic materials as reinforcements, notably W and steel fibers. The morphology of the reinforcement material is another variable of importance in metal matrix composites. The three major classes of reinforcement morphology are continuous fiber, chopped fiber or whisker, and particulate. Typically, the selection of the reinforcement morphology is determined by the desired property/cost combination. Generally, continuous fiber reinforced MMCs provide the highest properties in the direction of the fiber orientation but are the most expensive. Chopped fiber and whisker reinforced materials can produce significant property improvements in the plane or direction of their orientation, at somewhat lower cost. Particulates provide a comparatively more moderate but isotropic increase in properties and are typically available at the lowest cost. By adding to the three variables of metallic matrix, reinforcement material, and reinforcement morphology the further options of reinforcement volume fraction, orientation, and matrix alloy composition and heat treatment, it is apparent that there is a very wide range of available material combinations and resultant properties. This paper will focus on how MMCs have been applied in specific application areas.

  14. A Person-Centered Intervention in an International Peace Conference.

    ERIC Educational Resources Information Center

    Hughes, Marvalene Styles

    1988-01-01

    Notes that social scientists are exploring macro applications of human behavior theory to peace interventions. Provides an overview of an international intervention conducted by Carl R. Rogers and his colleagues. Describes the format of the Central American Challenge, an international conference conducted in Rust, Austria; conference participants;…

  15. Bridging Cultures with a Parent-Teacher Conference.

    ERIC Educational Resources Information Center

    Quiroz, Blanca; Greenfield, Patricia M.; Altchech, Marie

    1999-01-01

    Recent Latino immigrants may not realize that their children will be asked to relinquish collectivist values in pursuit of educational achievement. Finding child-led parent-teacher conferences incompatible with Latino values, a teacher training with the "Bridging Cultures Project" developed a less-threatening group-conference format. (10…

  16. Guide for Planning a High School Environmental Action Conference.

    ERIC Educational Resources Information Center

    Wanless, Angie, Comp.; And Others

    The purpose of this manual is to provide guidelines and suggestions for people organizing an environmental action conference for high school students. The format and planning suggestions are based on the methods used for a conference organized by the Wisconsin Center for Environmental Education in 1991. The bulk of the manual provides structure…

  17. A Person-Centered Intervention in an International Peace Conference.

    ERIC Educational Resources Information Center

    Hughes, Marvalene Styles

    1988-01-01

    Notes that social scientists are exploring macro applications of human behavior theory to peace interventions. Provides an overview of an international intervention conducted by Carl R. Rogers and his colleagues. Describes the format of the Central American Challenge, an international conference conducted in Rust, Austria; conference participants;…

  18. Writing Conferences and Some Applications for the EFL Classroom.

    ERIC Educational Resources Information Center

    Renner, Christopher

    1990-01-01

    A teacher of English as a Foreign Language (EFL) to adults in a non-English-speaking country describes use of classroom writing conferences to improve student language use and introduce writing into the communicative syllabus. The approach is based on a conference format and focuses on self-directed inquiry. Students are provided with monolingual…

  19. Bridging Cultures with a Parent-Teacher Conference.

    ERIC Educational Resources Information Center

    Quiroz, Blanca; Greenfield, Patricia M.; Altchech, Marie

    1999-01-01

    Recent Latino immigrants may not realize that their children will be asked to relinquish collectivist values in pursuit of educational achievement. Finding child-led parent-teacher conferences incompatible with Latino values, a teacher training with the "Bridging Cultures Project" developed a less-threatening group-conference format. (10…

  20. Training in Mental Health: Evaluation of the Telephone Conference Network.

    ERIC Educational Resources Information Center

    Connell, C.; Smyer, M. A.

    The Telephone Conference Network, sponsored by The Pennsylvania State University's Coordinating Council for Health Care, is designed as a cost-effective format for providing inservice training in geriatric mental health for individuals who serve the elderly. Institutions which subscribe to the Telephone Conference Network are equipped with a…

  1. Aluminum enhances inflammation and decreases mucosal healing in experimental colitis in mice

    PubMed Central

    Pineton de Chambrun, G; Body-Malapel, M; Frey-Wagner, I; Djouina, M; Deknuydt, F; Atrott, K; Esquerre, N; Altare, F; Neut, C; Arrieta, M C; Kanneganti, T-D; Rogler, G; Colombel, J-F; Cortot, A; Desreumaux, P; Vignal, C

    2014-01-01

    The increasing incidence of inflammatory bowel diseases (IBDs) in developing countries has highlighted the critical role of environmental pollutants as causative factors in their pathophysiology. Despite its ubiquity and immune toxicity, the impact of aluminum in the gut is not known. This study aimed to evaluate the effects of environmentally relevant intoxication with aluminum in murine models of colitis and to explore the underlying mechanisms. Oral administration of aluminum worsened intestinal inflammation in mice with 2,4,6-trinitrobenzene sulfonic acid- and dextran sodium sulfate-induced colitis and chronic colitis in interleukin 10-negative (IL10−/−) mice. Aluminum increased the intensity and duration of macroscopic and histologic inflammation, colonic myeloperoxidase activity, inflammatory cytokines expression, and decreased the epithelial cell renewal compared with control animals. Under basal conditions, aluminum impaired intestinal barrier function. In vitro, aluminum induced granuloma formation and synergized with lipopolysaccharide to stimulate inflammatory cytokines expression by epithelial cells. Deleterious effects of aluminum on intestinal inflammation and mucosal repair strongly suggest that aluminum might be an environmental IBD risk factor. PMID:24129165

  2. Scaleable Clean Aluminum Melting Systems

    SciTech Connect

    Han, Q.; Das, S.K.

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  3. Aluminum industry applications for OTEC

    SciTech Connect

    Jones, M.S.; Leshaw, D.; Sathyanarayana, K.; Sprouse, A.M.; Thiagarajan, V.

    1980-12-01

    The objective of the program is to study the integration issues which must be resolved to realize the market potential of ocean thermal energy conversion (OTEC) power for the aluminum industry. The study established, as a baseline, an OTEC plant with an electrical output of 100 MWe which would power an aluminum reduction plant. The reduction plant would have a nominal annual output of about 60,000 metric tons of aluminum metal. Three modes of operation were studied, viz: 1. A reduction plant on shore and a floating OTEC power plant moored offshore supplying energy by cable. 2. A reduction plant on shore and a floating OTEC power plant at sea supplying energy by means of an ''energy bridge.'' 3. A floating reduction plant on the same platform as the OTEC power plant. For the floating OTEC/aluminum plantship, three reduction processes were examined. 1. The conventional Hall process with prebaked anodes. 2. The drained cathode Hall cell process. 3. The aluminum chloride reduction process.

  4. Thermophysical Properties of Liquid Aluminum

    NASA Astrophysics Data System (ADS)

    Leitner, Matthias; Leitner, Thomas; Schmon, Alexander; Aziz, Kirmanj; Pottlacher, Gernot

    2017-06-01

    Ohmic pulse-heating with sub-microsecond time resolution is used to obtain thermophysical properties for aluminum in the liquid phase. Measurement of current through the sample, voltage drop across the sample, surface radiation, and volume expansion allow the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of the sample at melting and in the liquid phase. Thermal conductivity and thermal diffusivity as a function of temperature are estimated from resistivity data using the Wiedemann-Franz law. Data for liquid aluminum obtained by pulse-heating are quite rare because of the low melting temperature of aluminum with 933.47 K (660.32 °C), as the fast operating pyrometers used for the pulse-heating technique with rise times of about 100 ns generally might not be able to resolve the melting plateau of aluminum because they are not sensitive enough for such low temperature ranges. To overcome this obstacle, we constructed a new, fast pyrometer sensitive in this temperature region. Electromagnetic levitation, as the second experimental approach used, delivers data for surface tension (this quantity is not available by means of the pulse-heating technique) and for density of aluminum as a function of temperature. Data obtained will be extensively compared to existing literature data.

  5. 47 CFR 1.248 - Prehearing conferences; hearing conferences.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Prehearing conferences; hearing conferences. 1... Hearing Proceedings Prehearing Procedures § 1.248 Prehearing conferences; hearing conferences. (a) The... to appear at a specified time and place for a conference prior to a hearing, or to submit...

  6. Role of Exogenous Melatonin on Cell Proliferation and Oxidant/Antioxidant System in Aluminum-Induced Renal Toxicity.

    PubMed

    Karabulut-Bulan, Omur; Bayrak, Bertan Boran; Arda-Pirincci, Pelin; Sarikaya-Unal, Guner; Us, Huseyin; Yanardag, Refiye

    2015-11-01

    Aluminum has toxic potential on humans and animals when it accumulates in various tissues. It was shown in a number of studies that aluminum causes oxidative stress by free radical formation and lipid peroxidation in tissues and thus may cause damage in target organs. Although there are numerous studies investigating aluminum toxicity, biochemical mechanisms of the damage caused by aluminum have yet to be explained. Melatonin produced by pineal gland was shown to be an effective antioxidant. Since kidneys are target organs for aluminum accumulation and toxicity, we have studied the role of melatonin against aluminum-induced renal toxicity in rats. Wistar albino rats were divided into five groups. Group I served as control, and received only physiological saline; group II served as positive control for melatonin, and received ethanol and physiological saline; group III received melatonin (10 mg/kg); group IV received aluminum sulfate (5 mg/kg) and group V received aluminum sulfate and melatonin (in the same dose), injected three times a week for 1 month. Administration of aluminum caused degenerative changes in renal tissues, such as increase in metallothionein immunoreactivity and decrease in cell proliferation. Moreover, uric acid and lipid peroxidation levels and xanthine oxidase activity increased, while glutathione, catalase, superoxide dismutase, paraoxonase 1, glucose-6-phosphate dehydrogenase, and sodium potassium ATPase activities decreased. Administration of melatonin mostly prevented these symptoms. Results showed that melatonin is a potential beneficial agent for reducing damage in aluminum-induced renal toxicity.

  7. Spray Forming Aluminum - Final Report (Phase II)

    SciTech Connect

    D. D. Leon

    1999-07-08

    The U.S. Department of Energy - Office of Industrial Technology (DOE) has an objective to increase energy efficient and enhance competitiveness of American metals industries. To support this objective, ALCOA Inc. entered into a cooperative program to develop spray forming technology for aluminum. This Phase II of the DOE Spray Forming Program would translate bench scale spray forming technology into a cost effective world class process for commercialization. Developments under DOE Cooperative Agreement No. DE-FC07-94ID13238 occurred during two time periods due to budgetary constraints; April 1994 through September 1996 and October 1997 and December 1998. During these periods, ALCOA Inc developed a linear spray forming nozzle and specific support processes capable of scale-up for commercial production of aluminum sheet alloy products. Emphasis was given to alloys 3003 and 6111, both being commercially significant alloys used in the automotive industry. The report reviews research performed in the following areas: Nozzel Development, Fabrication, Deposition, Metal Characterization, Computer Simulation and Economics. With the formation of a Holding Company, all intellectual property developed in Phases I and II of the Project have been documented under separate cover for licensing to domestic producers.

  8. Regeneration of Aluminum Hydride Using Trimethylamine

    SciTech Connect

    D Lacina; J Reilly; Y Celebi; J Wegrzyn; J Johnson; J Graetz

    2011-12-31

    Aluminum hydride is an attractive reducing agent and energy storage compound possessing a low decomposition temperature and a high gravimetric and volumetric hydrogen density. However, it is thermodynamically unstable at room temperature and requires extremely high pressures to form the hydride from aluminum and hydrogen gas. Here, we describe an alternate method of synthesizing AlH{sub 3} using Ti-catalyzed Al powder, H{sub 2}, and trimethylamine (TMA) to form an alane adduct. The formation of trimethylamine alane occurs at modest hydrogen pressures ({approx}100 bar), forming the 2:1 bis complex (2 trimethylamine/AlH{sub 3}). Along with the hydrogenation product, mono (1:1) and bis (2:1) standards of TMA-AlH{sub 3} were prepared and characterized using X-ray diffraction and Raman spectroscopy. X-ray absorption spectroscopy of the reaction products showed that the Ti catalyst remains with the unreacted Al powder after hydrogenation and is not present in the alane adduct. We also demonstrate that TMA can be transaminated with triethylamine to form triethylamine alane, which can easily be separated to recover AlH{sub 3}.

  9. Determination of stress responses induced by aluminum in maize (Zea mays).

    PubMed

    Vardar, Filiz; Ismailoğlu, Işil; Inan, Deniz; Unal, Meral

    2011-06-01

    To assess the alternative responses to aluminum toxicity, maize (Zea mays L. cv Karadeniz yıldızı) roots were exposed to different concentrations of AlCl3 (150, 300 and 450 μM). Aluminum reduced the root elongation by 39.6% in 150 μM, 44.1% in 300 μM, 50.1% in 450 μM AlCl3 after 96 h period. To correlate the root elongation with the alternative stress responses including aluminum accumulation, lipid peroxidation, mitotic abnormalities, reduction of starch content, intracellular Ca2+ accumulation, callose formation, lignin deposition and peroxidase activity, cytochemical and biochemical tests were performed. The results indicated that aluminum accumulation and lipid peroxidation were observed more densely on the root cap and the outer cortex cells. In addition to morphological deformations, cytochemical analysis displayed cellular deformations. Furthermore, mitotic abnormalities were observed such as c-mitosis, micronuclei, bi- and trinucleated cells in aluminum treated root tips. Aluminum treatment induced starch reduction, callose formation, lignin accumulation and intracellular Ca2+ increase. Moreover, the peroxidase activity increased significantly by 3, 4.4 and 7.7 times higher than in that of control after 96 h, respectively. In conclusion, aluminum is significantly stressful in maize culminating in morphological and cellular alterations.

  10. Aluminum speciation in crustal fluids revisited

    NASA Astrophysics Data System (ADS)

    Tagirov, Boris; Schott, Jacques

    2001-11-01

    Aluminum speciation in crustal fluids is assessed by means of standard thermodynamic properties at 25°C, 1 bar, and revised Helgeson-Kirkham-Flowers (HKF) (Tanger J. C. IV and Helgeson H. C., "Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Revised equations of state for the standard partial molal properties of ions and electrolytes," Am. J. Sci. 288, 19-98, 1988) equations of state parameters for aqueous species in the system Al-O-H-Na-Si-Cl-F-SO 4 derived from recent experimental data with the help of isocoulombic reactions and correlations among parameters in the HKF model. In acidic to neutral hydrothermal solutions and for fluorine concentrations in excess of 1 ppm, the fluoride complexes AlF n3-n dominate Al speciation at temperature (T) < 100°C, whereas the hydroxide fluoride species Al(OH) 2F (aq)0 and AlOHF 20(aq) are dominant up to ˜400°C. In high-temperature (T > 300°C) hydrothermal and metamorphic fluids, aluminum mobility is considerably enhanced by formation of NaAl(OH) 3F (aq)0 and NaAl(OH) 2F 20(aq) ion paired mixed species. NaAl(OH) 2F 20(aq) controls Al transport in granite-derived fluids and during greisenization. At alkaline pH, Al(OH) 4-, Al(OH) 3H 3SiO 4-, and the NaAl(OH) 40(aq) ion-pair are the dominant Al species. Thermodynamic calculations show that as a result of strong interactions of Al(aq) with NaOH, NaF, HF, and SiO 2(aq) present in crustal fluids, the concentrations of aluminum in equilibrium with Al-bearing minerals can be several orders of magnitude higher than those calculated assuming that only Al hydroxyde complexes are formed. Interactions with these components are likely to be responsible for aluminum mobility during hydrothermal and metamorphic reactions.

  11. Explosion bonding: aluminum-magnesium alloys bonded to austenitic stainless steel

    SciTech Connect

    Patterson, R.A.

    1982-01-01

    The explosion bonding of 5000 series aluminum alloys to 300 series stainless steel alloys is summarized. The process technique involves a parallel gap arrangement with copper or aluminum bonding aids. Successful bonds have been achieved using either a single shot process for joining the trilayer clad or a sequential shot technique for each metal component. Bond success is monitored through a combined metallographic and tensile strength evaluation. Tensile properties are shown to be strongly dependent upon process parameters and the amount of intermetallic formation at the aluminum bond interface. Empirical data has been compared with experimental and destructive test results to determine the optimum procedures.

  12. GE STEM Teacher's Conference

    NASA Image and Video Library

    2017-07-13

    Teachers participate in the Rocketry Engineering Design Challenge during the 2017 GE Foundation High School STEM Integration Conference at the Center for Space Education at NASA's Kennedy Space Center. High school teachers from across the country took part in the week-long conference, which is designed to explore effective ways for teachers, schools and districts from across the country to integrate STEM throughout the curriculum. The conference is a partnership between GE Foundation and the National Science Teachers Association.

  13. Proceedings of the 21st annual offshore technology conference. Volume 1

    SciTech Connect

    Not Available

    1989-01-01

    This book contains the proceedings of a conference on offshore technology. Topics covered include: underwater wet welding of higher strength offshore steels; the proposed extended-reach drilling project; North Sea experience with aluminum drillpipe; and load transfer mechanism to offshore jackets during pile driving.

  14. Rechargeable Aluminum-Ion Batteries

    SciTech Connect

    Paranthaman, Mariappan Parans; Liu, Hansan; Sun, Xiao-Guang; Dai, Sheng; Brown, Gilbert M

    2015-01-01

    This chapter reports on the development of rechargeable aluminum-ion batteries. A possible concept of rechargeable aluminum/aluminum-ion battery based on low-cost, earth-abundant Al anode, ionic liquid EMImCl:AlCl3 (1-ethyl-3-methyl imidazolium chloroaluminate) electrolytes and MnO2 cathode has been proposed. Al anode has been reported to show good reversibility in acid melts. However, due to the problems in demonstrating the reversibility in cathodes, alternate battery cathodes and battery concepts have also been presented. New ionic liquid electrolytes for reversible Al dissolution and deposition are needed in the future for replacing corrosive EMImCl:AlCl3 electrolytes.

  15. PREPARATION OF DIBASIC ALUMINUM NITRATE

    DOEpatents

    Gresky, A.T.; Nurmi, E.O.; Foster, D.L.; Wischow, R.P.; Savolainen, J.E.

    1960-04-01

    A method is given for the preparation and recovery of basic aluminum nltrates having an OH: Al ratio of at least two, comprising two steps. First, metallic aluminum is dissolved in aqueous Al(NO/sub 3/)/sub 3/, in the presence of a small quantity of elemental or ionic mercury, to increase its Al: NO/sub 3/ ratio into the range 1 to 1.2. The resulting aqueous solution is then added to an excess of a special organic solvent, typically a mixture of five parts methanol and six parts diethyl ether, whereupon the basic aluminum nitrate, e.g. Al/sub 6/(OH)/sub 13/-(NO/sub 3/)/sub 5/, recoverably precipitates.

  16. Recycling of aluminum salt cake

    SciTech Connect

    Jody, B.J.; Daniels, E.J.; Bonsignore, P.V.; Karvelas, D.E.

    1991-12-01

    The secondary aluminum industry generates more than 110 {times} 10{sup 3} tons of salt-cake waste every year. This waste stream contains about 3--5% aluminum, 15--30% aluminum oxide, 30--40% sodium chloride, and 20--30% potassium chloride. As much as 50% of the content of this waste is combined salt (sodium and potassium chlorides). Salt-cake waste is currently disposed of in conventional landfills. In addition, over 50 {times} 10{sup 3} tons of black dross that is not economical to reprocess a rotary furnace for aluminum recovery ends up in landfills. The composition of the dross is similar to that of salt cake, except that it contains higher concentrations of aluminum (up to 20%) and correspondingly lower amounts of salts. Because of the high solubility of the salts in water, these residues, when put in landfills, represent a potential source of pollution to surface-water and groundwater supplies. The increasing number of environmental regulations on the generation and disposal of industrial wastes are likely to restrict the disposal of these salt-containing wastes in conventional landfills. Processes exist that employ the dissolution and recovery of the salts from the waste stream. These wet-processing methods are economical only when the aluminum concentration in that waste exceeds about 10%. Argonne National Laboratory (ANL) conducted a study in which existing technologies were reviewed and new concepts that are potentially more cost-effective than existing processes were developed and evaluated. These include freeze crystallization, solvent/antisolvent extraction, common-ion effect, high-pressure/high-temperature process, and capillary-effect systems. This paper presents some of the technical and economic results of the aforementioned ANL study.

  17. Reclaiming the morbidity and mortality conference: between Codman and Kundera.

    PubMed

    Prasad, Vinay

    2010-12-01

    In recent years, a number of commentators have voiced unease about the direction and format of the Morbidity and Mortality (M&M) conference. Drawing on historical, literary and philosophical perspectives, and detailing the recent shift towards incorporating systems-based approaches to healthcare safety into the M&M, this article explores the nature and purpose of the M&M conference. It is argued that improving future health outcomes is insufficient as the goal of the conference. Instead, transcending hubris should be an endorsed objective. This paper aims to provide a definition and philosophical framework for the M&M conference.

  18. Dissolution and Separation of Aluminum and Aluminosilicates

    DOE PAGES

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; ...

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

  19. Inert Reassessment Document for Aluminum Isopropoxide

    EPA Pesticide Factsheets

    Aluminum isopropylate is used to make aluminum soaps, paints, waterproofingfinishes for textiles, and other chemicals. It is used as a dehydrating agent, a viscosity adjustor forvarnishes, an intermediate for pharmaceuticals, and as an antitranspirant.

  20. Dissolution and Separation of Aluminum and Aluminosilicates

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  1. The effects of fumed silica and barite on the aluminum resistance of alumina castables

    NASA Astrophysics Data System (ADS)

    Afshar, Saied; Gaubert, Christophe; Allaire, Claude

    2003-11-01

    A study of the effects of microsilica and barium sulfate as additives in high-tabular alumina castables on cold and hot modulus of rupture, porosity, thermal shock, and corrosion resistance to aluminum attack is reported in this article. This investigation underlined the importance of the quality of fumed silica on the physical and mechanical properties of refractory castables, and also confirmed the importance of celsian formation during firing in the protection of refractory against aluminum attack.

  2. The effect of zinc on the aluminum anode of the aluminum-air battery

    NASA Astrophysics Data System (ADS)

    Tang, Yougen; Lu, Lingbin; Roesky, Herbert W.; Wang, Laiwen; Huang, Baiyun

    Aluminum is an ideal material for batteries, due to its excellent electrochemical performance. Herein, the effect of zinc on the aluminum anode of the aluminum-air battery, as an additive for aluminum alloy and electrolytes, has been studied. The results show that zinc can decrease the anodic polarization, restrain the hydrogen evolution and increase the anodic utilization rate.

  3. Advances in aluminum casting technology

    SciTech Connect

    Tiryakioglu, M.; Campbell, J.

    1998-01-01

    This symposium focuses on the improvements of aluminum casting quality and reliability through a better understanding of processes and process variables, and explores the latest innovations in casting-process design that allow increasing use of the castings to replace complex assemblies and heavy steel and cast-iron components in aerospace and automotive applications. Presented are 35 papers by international experts in the various aspects of the subject. The contents include: Semisolid casting; Computer-aided designing of molds and castings; Casting-process modeling; Aluminum-matrix composite castings; HIPing of castings; Progress in the US car project; Die casting and die design; and Solidification and properties.

  4. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C. Joseph; Dispennette, John M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

  5. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C.J.; Dispennette, J.M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

  6. 76 FR 64083 - Reliability Technical Conference; Notice of Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Reliability Technical Conference; Notice of Technical Conference Take notice that the Federal Energy Regulatory Commission will hold a Technical Conference on Tuesday, November...

  7. Mineral resource of the month: aluminum

    USGS Publications Warehouse

    Bray, E. Lee

    2012-01-01

    The article offers information on aluminum, a mineral resource which is described as the third-most abundant element in Earth's crust. According to the article, aluminum is the second-most used metal. Hans Christian Oersted, a Danish chemist, was the first to isolate aluminum in the laboratory. Aluminum is described as lightweight, corrosion-resistant and an excellent conductor of electricity and heat.

  8. RECOVERY OF ALUMINUM FROM FISSION PRODUCTS

    DOEpatents

    Blanco, R.E.; Higgins, I.R.

    1962-11-20

    A method is given for recovertng aluminum values from aqueous solutions containing said values together with fission products. A mixture of Fe/sub 2/O/ sub 3/ and MnO/sub 2/ is added to a solution containing aluminum and fission products. The resulting aluminum-containing supernatant is then separated from the fission product-bearing metal oxide precipitate and is contacted with a cation exchange resin. The aluminum sorbed on the resin is then eluted and recovered. (AEC)

  9. All-Aluminum Transverse Platelet Injector

    DTIC Science & Technology

    1978-01-25

    to the low density material. The 1xx$nafter described lightweight platelet injector includes an aluminum transverse platelet faceplate joined to an... aluminum body 15 with the electron beam 20 welds 21. This allows the fabrication of an all aluminum transverse platelet iinjector capable of replacing the...1 87 1-93 Serial No _ 872,?193 Filing 1)’ 25Jan 78( * Inventg/ Samuel E./Adair --: i - ------ NOC E . . . / All- Aluminum Transverse Platelet

  10. Blood aluminum levels as a function of aluminum intake from drinking water

    SciTech Connect

    Turnquest, E.M.; Hallenbeck, W.H. )

    1991-04-01

    Questions regarding the health effects of aluminum are still unanswered. The speciation, pharmacokinetics, and toxicity of aluminum are not well understood. Furthermore, no animal or human studies of aluminum absorption have been reported using drinking water as the source of aluminum. The following experiment attempted to reach a better understanding of the bioavailability of aluminum from drinking water. Its objective was to determine whether or not increased aluminum ingestion from drinking water would be reflected in increased serum and whole blood aluminum levels in the baboon experimental model.

  11. Hydrothermal Oxidation of Aluminum,

    DTIC Science & Technology

    surfaces were examined by X-ray diffraction, soft X-ray emission spectroscopy, and scanning electron microscopy (SEM). Crystalline product phases formed on...the surfaces over the p-t range were bayerite , boehmite, and corundum, each in a fairly well defined region. Along the 10,000 psi isobar bayerite ...SEM revealed the formation of dense mat surfaces, amorphous to X-rays, in early stages of treatment in the bayerite and boehmite reaction regions

  12. Diode laser welding of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-01

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  13. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-04

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  14. Quantitative in situ nanoindentation of aluminum films

    SciTech Connect

    Minor, Andrew M.; Stach, Eric A.; Morris Jr., J.W.

    2001-04-04

    We report the development of a method for quantitative, in situ nanoindentation in an electron microscope and its application to study the onset of deformation during the nanoindentation of aluminum films. The load-displacement curve developed during in situ nanoindentation shows the characteristic ''staircase'' instability at the onset of plastic deformation. The instability corresponds to the first appearance of dislocations in previously defect-free grains, and occurs at a force near that measured in conventional nanoindentation experiments on similarly oriented Al grains. Plastic deformation proceeds through the formation and propagation of prismatic loops punched into the material, and half-loops that emanate from the sample surface. This new experimental technique permits the direct observation of the microstructural mechanisms that operate at the onset of deformation.

  15. Alkaline oxide conversion coatings for aluminum alloys

    SciTech Connect

    Buchheit, R.G.

    1996-02-01

    Three related conversion coating methods are described that are based on film formation which occurs when aluminum alloys are exposed to alkaline Li salt solutions. Representative examples of the processing methods, resulting coating structure, composition and morphology are presented. The corrosion resistance of these coatings to aerated 0.5 M NaCl solution has been evaluated as a function of total processing time using electrochemical impedance spectroscopy (EIS). This evaluation shows that excellent corrosion resistance can be uniformly achieved using no more than 20 minutes of process time for 6061-T6. Using current methods a minimum of 80 minutes of process time is required to get marginally acceptable corrosion resistance for 2024-T3. Longer processing times are required to achieve uniformly good corrosion resistance.

  16. Taking the Conference to the Teachers: Workshops to Improve Language Teaching.

    ERIC Educational Resources Information Center

    Di Donato, Robert; Nollendorfs, Valters

    1983-01-01

    Through a network of extension workshops, foreign language conferences can be brought to many teachers not ordinarily attending them. Using existing formats, selected participants would attend conference workshops, then conduct similar workshops in their local areas. A funding mechanism could be established within the conference governing body.…

  17. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely...

  18. 21 CFR 73.2645 - Aluminum powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  19. 21 CFR 73.2645 - Aluminum powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  20. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  1. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely...

  2. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  3. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  4. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  5. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  6. 21 CFR 73.2645 - Aluminum powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  7. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  8. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  9. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely used as a source of niacin in...

  10. 75 FR 80527 - Aluminum Extrusions From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ... COMMISSION Aluminum Extrusions From China AGENCY: United States International Trade Commission. ACTION... retarded, by reason of subsidized and less-than-fair-value imports from China of aluminum extrusions... contained in Aluminum Extrusions From the People's Republic of China: Notice of Preliminary Determination of...

  11. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  12. 21 CFR 73.2645 - Aluminum powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  13. 21 CFR 73.2645 - Aluminum powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Aluminum powder. 73.2645 Section 73.2645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2645 Aluminum powder. (a) Identity and specifications. The color additive aluminum powder shall conform in identity and specifications to the requirements of...

  14. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance...

  15. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely...

  16. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance is generally recognized as safe when used in...

  17. [Cognitive disorders among welders exposed to aluminum].

    PubMed

    Giorgianni, C; Faranda, M; Brecciaroli, R; Beninato, G; Saffioti, G; Muraca, G; Congia, P; Catanoso, R; Agostani, G; Abbate, C

    2003-01-01

    In order to evaluate the relationship between exposure to aluminum and cognitive functions, a group of 50 aluminum welders underwent to the following neuropsychological tests: Wechsler Memory Scale, Color-Word Test and Raven Progressives Matrices test. The results of the tests showed a reduction of memory, of concentration and a slight reduction of attention. The authors conclude that aluminum exposure leads cognitive changes.

  18. Effective use of critique and dialogue at scholarly conferences.

    PubMed

    DeMarco, Rosanna F; Horowitz, June Andrews; McCurry, Mary K

    2005-01-01

    In this article, the authors offer a solution to a phenomenon identified as "silencing" among nurse colleagues during national, regional, and international scholarly conferences. Through an electronic anonymous survey, data were collected regarding perceptions of the structure and process at scholarly nursing conferences. The need for critique and dialogue while sharing research ideas or findings is identified as a means to encourage direct exchange at professional conferences. Based on an examination of the process of critique and dialogue, and theories that explain why honest and direct dialogue are sometimes subdued, the authors propose a model of constructive scholarly dialogue for conference participation. The goals of implementing this model are to make scholarly exchanges normative at nursing conferences, and to revise standard conference formats so that constructive critique and dialogue are encouraged actively. The likely outcomes include improved nursing science and professional development of nurses.

  19. Formation Mechanism of CaO-SiO2-Al2O3-(MgO) Inclusions in Si-Mn-Killed Steel with Limited Aluminum Content During the Low Basicity Slag Refining

    NASA Astrophysics Data System (ADS)

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin

    2016-02-01

    Pilot trails were carried out to study the formation mechanism of CaO-SiO2-Al2O3-(MgO) inclusions in tire cord steel. 48 samples were taken from 8 heats of liquid steel during secondary refining, which were subsequently examined by an automatic scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Characteristics of thousands of oxide inclusions at different refining stages were obtained, including their compositions, sizes, morphologies, etc. Based on the obtained information of inclusions, details during formation of CaO-SiO2-Al2O3-(MgO) inclusions were revealed and a new mechanism was proposed, including their origin, formation, and evolution during the refining process. It was found that CaO-SiO2-Al2O3-(MgO) inclusions were initially originated from the CaO-SiO2-MnO-(MgO) inclusions, which were formed during BOF tapping by the coalescence between MnO-SiO2 deoxidation products and the emulsified slag particles because of violent flow of steel. This can be well confirmed by the evaluation of the formation thermodynamics of CaO-SiO2-MnO-(MgO) inclusions, which was proved very difficult to be produced by intrinsic reactions inside liquid steel. Because of chemical reactions between CaO-SiO2-MnO-(MgO) inclusions and molten steel, they were mainly changed into CaO-SiO2-MnO-Al2O3-(MgO) and partially into CaO-SiO2-Al2O3-(MgO), which may be detrimental to the cold drawing ability of coils. Based on this finding, improvements were made in industrial production during BOF tapping and secondary refining. The results indicated that such (CaO-SiO2)-based inclusions existed in conventional process were effectively decreased after the improvements.

  20. Deposition of Amorphous Aluminum Alloys as a Replacement for Aluminum Cladding

    DTIC Science & Technology

    2009-02-05

    1 DEPOSITION OF AMORPHOUS ALUMINUM ALLOYS AS A REPLACEMENT FOR ALUMINUM CLADDING US Army Corrosion Summit February 3-5, 2009 Clearwater, FL Ben...REPORT TYPE 3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Depostion of Amorphous Aluminum Alloys as a Replacement for Aluminum ...Tantalum for gun barrel applications WC-Co-Cr for landing gear ID Co-Cr-Al-Y bond coat for thermal barrier system Pure aluminum for Cd replacement