Sample records for aluminum hydrogen cluster

  1. Assembling of hydrogenated aluminum clusters

    Energy Technology Data Exchange (ETDEWEB)

    Duque, F.; Mananes, A. [Dept. de Fisica Moderna, Universidad de Cantabria, Santander (Spain); Molina, L.M.; Lopez, M.J.; Alonso, J.A. [Dept. de Fisica Teorica, Universidad de Valladolid (Spain)


    The electronic and atomic structure of Al{sub 13}H has been studied using Density Functional Theory. Al{sub 13}H has closed electronic shells. This makes the cluster very stable and suggests that it could be a candidate to form cluster assembled solids. The interaction between two Al{sub 13}H clusters was analyzed and we found that the two units preserve their identities in the dimer. A cubic-like solid phase assembled from Al{sub 13}H units was then modeled. In that solid the clusters retain much of their identity. Molecular dynamics runs show that the structure of the assembled solid is stable at least up to 150 K. A favorable relative orientation of the clusters with respect to their neighbors is critical for the stability of that solid. (orig.)

  2. Structure of Liquid Aluminum and Hydrogen Absorption

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; DAI Yongbing; WANG Jun; SHU Da; SUN Baode


    The hydrogen content in aluminum melts at different temperature was detected. The structure in aluminum melts was investigated by molecular dynamics simulation. The first peak position of pair correlation function, atomic coordination number and viscosity of aluminum melts were calculated and they changed abnormally in the same temperature range. The mechanism of hydrogen absorption has been discussed. From molecular dynamics calculations, the interdependence between melt structural properties and hydrogen absorption were obtained.

  3. Reaction of Aluminum with Water to Produce Hydrogen - 2010 Update

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thomas, George [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    A Study of Issues Related to the Use of Aluminum for On-Board Vehicular Hydrogen Storage The purpose of this White Paper is to describe and evaluate the potential of aluminum-water reactions for the production of hydrogen for on-board hydrogen-powered vehicle applications. Although the concept of reacting aluminum metal with water to produce hydrogen is not new, there have been a number of recent claims that such aluminum-water reactions might be employed to power fuel cell devices for portable applications such as emergency generators and laptop computers, and might even be considered for possible use as the hydrogen source for fuel cell-powered vehicles.

  4. Hydrogen storage in sodium aluminum hydride.

    Energy Technology Data Exchange (ETDEWEB)

    Ozolins, Vidvuds; Herberg, J.L. (Lawrence Livermore National Laboratories, Livermore, CA); McCarty, Kevin F.; Maxwell, Robert S. (Lawrence Livermore National Laboratories, Livermore, CA); Stumpf, Roland Rudolph; Majzoub, Eric H.


    Sodium aluminum hydride, NaAlH{sub 4}, has been studied for use as a hydrogen storage material. The effect of Ti, as a few mol. % dopant in the system to increase kinetics of hydrogen sorption, is studied with respect to changes in lattice structure of the crystal. No Ti substitution is found in the crystal lattice. Electronic structure calculations indicate that the NaAlH{sub 4} and Na{sub 3}AlH{sub 6} structures are complex-ionic hydrides with Na{sup +} cations and AlH{sub 4}{sup -} and AlH{sub 6}{sup 3-} anions, respectively. Compound formation studies indicate the primary Ti-compound formed when doping the material at 33 at. % is TiAl{sub 3} , and likely Ti-Al compounds at lower doping rates. A general study of sorption kinetics of NaAlH{sub 4}, when doped with a variety of Ti-halide compounds, indicates a uniform response with the kinetics similar for all dopants. NMR multiple quantum studies of solution-doped samples indicate solvent interaction with the doped alanate. Raman spectroscopy was used to study the lattice dynamics of NaAlH{sub 4}, and illustrated the molecular ionic nature of the lattice as a separation of vibrational modes between the AlH{sub 4}{sup -} anion-modes and lattice-modes. In-situ Raman measurements indicate a stable AlH{sub 4}{sup -} anion that is stable at the melting temperature of NaAlH{sub 4}, indicating that Ti-dopants must affect the Al-H bond strength.

  5. Synthesis and Hydrogen Desorption Properties of Aluminum Hydrides. (United States)

    Jeong, Wanseop; Lee, Sang-Hwa; Kim, Jaeyong


    Aluminum hydride (AlH3 or alane) is known to store maximum 10.1 wt.% of hydrogen at relatively low temperature (hydrogen desorption are still not clear. To understand the desorption properties of hydrogen in alane, thermodynamically stable α-AlH3 was synthesized by employing an ethereal reaction method. The dependence of pathways on phase formation and the properties of hydrogen evolution were investigated, and the results were compared with the ones for γ-AlH3. It was found that γ-AlH3 requires 10 degrees C higher than that of γ-AlH3 to form, and its decomposition rate demonstrated enhanced endothermic stabilities. For desorption, all hydrogen atoms of alane evolved under an isothermal condition at 138 degrees C in less than 1 hour, and the sample completely transformed to pure aluminum. Our results show that the total amount of desorbed hydrogen from α-AlH3 exceeded 9.05 wt.%, with a possibility of further increase. Easy synthesis, thermal stability, and a large amount of hydrogen desorption of alane fulfill the requirements for light-weight hydrogen storage materials once the pathway of hydrogen cycling is provided.

  6. Photoelectron spectroscopic study of carbon aluminum hydride cluster anions (United States)

    Zhang, Xinxing; Wang, Haopeng; Ganteför, Gerd; Eichhorn, Bryan W.; Kiran, Boggavarapu; Bowen, Kit H.


    Numerous previously unknown carbon aluminum hydride cluster anions were generated in the gas phase, identified by time-of-flight mass spectrometry and characterized by anion photoelectron spectroscopy, revealing their electronic structure. Density functional theory calculations on the CAl5-9H- and CAl5-7H2- found that several of them possess unusually high carbon atom coordination numbers. These cluster compositions have potential as the basis for new energetic materials.

  7. Classical and quantum physics of hydrogen clusters. (United States)

    Mezzacapo, Fabio; Boninsegni, Massimo


    We present results of a comprehensive theoretical investigation of the low temperature (T) properties of clusters of para-hydrogen (p-H(2)), both pristine as well as doped with isotopic impurities (i.e., ortho-deuterium, o-D(2)). We study clusters comprising up to N = 40 molecules, by means of quantum simulations based on the continuous-space Worm algorithm. Pristine p-H(2) clusters are liquid-like and superfluid in the [Formula: see text] limit. The superfluid signal is uniform throughout these clusters; it is underlain by long cycles of permutation of molecules. Clusters with more than 22 molecules display solid-like, essentially classical behavior at temperatures down to T∼1 K; some of them are seen to turn liquid-like at sufficiently low T (quantum melting).

  8. Rovibrational Spectroscopy of Aluminum Carbonyl Clusters in Helium Nanodroplets (United States)

    Liang, T.; Morrison, A. M.; Flynn, S. D.; Douberly, G. E.


    Helium nanodroplet isolation and a tunable quantum cascade laser are used to probe the fundamental CO stretch bands of Aluminum Carbonyl complexes, Al-(CO)N (n ≤ 5). The droplets are doped with single aluminum atoms via the resistive heating of an aluminum wetted tantalum wire. The downstream sequential pick-up of CO molecules leads to the rapid formation and cooling of Al-(CO)N clusters within the droplets. Near 1900 Cm-1, rotational fine structure is resolved in bands that are assigned to the CO stretch of a 2Π1/2 linear Al-CO species, and the asymmetric and symmetric CO stretch vibrations of a planar C2v Al-(CO)2 complex in a 2B1 electronic state. Bands corresponding to clusters with n ≥ 3 lack resolved rotational fine structure; nevertheless, the small frequency shifts from the n=2 bands indicate that these clusters consist of an Al-(CO)2 core with additional CO molecules attached via van-der-Waals interactions. A second n=2 band is observed near the CO stretch of Al-CO, indicating a local minimum on the n=2 potential consisting of an ``unreacted" Al-CO-(CO) cluster. The linewidth of this band is ˜0.5 cm-1, which is over 50 times broader than transitions within the Al-CO band. The additional broadening is consistent with a homogeneous mechanism corresponding to a rapid vibrational excitation induced reaction within the Al-CO-(CO) cluster to form the covalently bonded Al-(CO)2 complex. For the n=1,2 complexes, CCSD(T) calculations and Natural Bond Orbital (NBO) analyses are carried out to investigate the nature of the bonding in these complexes. The NBO calculations show that both π ``back" donation (from the occupied aluminum p-orbital into the π antibonding CO orbital) and σ donation (from CO into the empty aluminum p-orbitals) play a significant role in the bonding, analogous to transition metal carbonyl complexes. The large redshift of the CO stretch vibrations is consistent with this bonding analysis.

  9. Ground state structures and properties of small hydrogenated silicon clusters

    Indian Academy of Sciences (India)

    R Prasad


    We present results for ground state structures and properties of small hydrogenated silicon clusters using the Car–Parrinello molecular dynamics with simulated annealing. We discuss the nature of bonding of hydrogen in these clusters. We find that hydrogen can form a bridge like Si–H–Si bond connecting two silicon atoms. We find that in the case of a compact and closed silicon cluster hydrogen bonds to the silicon cluster from outside. To understand the structural evolutions and properties of silicon cluster due to hydrogenation, we have studied the cohesive energy and first excited electronic level gap of clusters as a function of hydrogenation. We find that first excited electronic level gap of Si and SiH fluctuates as function of size and this may provide a first principle basis for the short-range potential fluctuations in hydrogenated amorphous silicon. The stability of hydrogenated silicon clusters is also discussed.

  10. The electronic structure of free aluminum clusters: metallicity and plasmons. (United States)

    Andersson, Tomas; Zhang, Chaofan; Tchaplyguine, Maxim; Svensson, Svante; Mårtensson, Nils; Björneholm, Olle


    The electronic structure of free aluminum clusters with ∼3-4 nm radius has been investigated using synchrotron radiation-based photoelectron and Auger electron spectroscopy. A beam of free clusters has been produced using a gas-aggregation source. The 2p core level and the valence band have been probed. Photoelectron energy-loss features corresponding to both bulk and surface plasmon excitation following photoionization of the 2p level have been observed, and the excitation energies have been derived. In contrast to some expectations, the loss features have been detected at energies very close to those of the macroscopic solid. The results are discussed from the point of view of metallic properties in nanoparticles with a finite number of constituent atoms.

  11. The electronic structure of free aluminum clusters: Metallicity and plasmons (United States)

    Andersson, Tomas; Zhang, Chaofan; Tchaplyguine, Maxim; Svensson, Svante; Mârtensson, Nils; Björneholm, Olle


    The electronic structure of free aluminum clusters with ˜3-4 nm radius has been investigated using synchrotron radiation-based photoelectron and Auger electron spectroscopy. A beam of free clusters has been produced using a gas-aggregation source. The 2p core level and the valence band have been probed. Photoelectron energy-loss features corresponding to both bulk and surface plasmon excitation following photoionization of the 2p level have been observed, and the excitation energies have been derived. In contrast to some expectations, the loss features have been detected at energies very close to those of the macroscopic solid. The results are discussed from the point of view of metallic properties in nanoparticles with a finite number of constituent atoms.

  12. Oxidation dynamics of nanophase aluminum clusters : a molecular dynamics study.

    Energy Technology Data Exchange (ETDEWEB)

    Ogata, S.


    Oxidation of an aluminum nanocluster (252,158 atoms) of radius 100{angstrom} placed in gaseous oxygen (530,727 atoms) is investigated by performing molecular-dynamics simulations on parallel computers. The simulation takes into account the effect of charge transfer between Al and O based on the electronegativity equalization principles. We find that the oxidation starts at the surface of the cluster and the oxide layer grows to a thickness of {approximately}28{angstrom}. Evolutions of local temperature and densities of Al and O are investigated. The surface oxide melts because of the high temperature resulting from the release of energy associated with Al-O bondings. Amorphous surface-oxides are obtained by quenching the cluster. Vibrational density-of-states for the surface oxide is analyzed through comparisons with those for crystalline Al, Al nanocluster, and {alpha}-Al{sub 2}O{sub 3}.

  13. Condensation and Storage of Hydrogen Cluster Ions (United States)


    CA, October 1987. 30. Casero , R. and Soler, J. M., personal communication. 31. Echt, 0., Multiply Charged Clusters, The Physics and Chemistry of...Physics of a Single Electron or Ion in a Panning Trap," Rev. Mod. Phys., Vol. 58, No. 1, pp. 233-311, January 1986. 35. Mitchell, J., The Role of...Determination of Narrow Mul- tichannel Rcsonances: Application to Hydrogen Molecular Ion (H3)", J. Phys. Chem. 90(16), 3595-9 (1986). 15. Pan , Fu Shih

  14. Solid propellant exhausted aluminum oxide and hydrogen chloride - Environmental considerations (United States)

    Cofer, W. R., III; Winstead, E. L.; Purgold, G. C.; Edahl, R. A.


    Measurements of gaseous hydrogen chloride (HCl) and particulate aluminum oxide (Al2O3) were made during penetrations of five Space Shuttle exhaust clouds and one static ground test firing of a shuttle booster. Instrumented aircraft were used to penetrate exhaust clouds and to measure and/or collect samples of exhaust for subsequent analyses. The focus was on the primary solid rocket motor exhaust products, HCl and Al2O3, from the Space Shuttle's solid boosters. Time-dependent behavior of HCl was determined for the exhaust clouds. Composition, morphology, surface chemistry, and particle size distributions were determined for the exhausted Al2O3. Results determined for the exhaust cloud from the static test firing were complicated by having large amounts of entrained alkaline ground debris (soil) in the lofted cloud. The entrained debris may have contributed to neutralization of in-cloud HCl.

  15. Aluminum chloride for accelerating hydrogen generation from sodium borohydride (United States)

    Demirci, U. B.; Akdim, O.; Miele, P.

    The present research paper reports preliminary results about the utilization of anhydrous aluminum chloride (AlCl 3) for accelerating hydrogen generation through hydrolysis of aqueous solution of sodium borohydride (NaBH 4) at 80 °C. To the best of our knowledge, AlCl 3 has never been considered for that reaction although many transition metal salts had already been assessed. AlCl 3 reactivity was compared to those of AlCl 3·6H 2O, AlF 3, CoCl 2, RuCl 3 and NiCl 2. With AlCl 3 and a NaBH 4 solution having a gravimetric hydrogen storage capacity (GHSC) of 2.9 wt.%, almost 100% hydrogen was generated in few seconds, i.e., with a hydrogen generation rate (HGR) of 354 L min -1 g -1(Al). This HGR is one of the highest rates ever reported. Higher HGRs were obtained by mixing AlCl 3 with CoCl2, RuCl 3 or NiCl 2. For example, the system RuCl 3:AlCl 3 (50:50 mass proportion) showed a HGR > 1000 L min -1 g -1(Ru:Al). The hydrolysis by-products (once dried) were identified (by XRD, IR and elemental analysis) as being Al(OH) 3, NaCl and Na 2B(OH) 4Cl and it was observed that even in situ formed Al(OH) 3 has catalytic abilities with HGRs of 5 L min -1 g -1(Al). All of these preliminary results are discussed, which concludes that AlCl 3 has a potential as accelerator for single-use NaBH 4-based storage system.

  16. Coupling a PEM fuel cell and the hydrogen generation from aluminum waste cans

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Susana Silva; Albanil Sanchez, Loyda; Alvarez Gallegos, Alberto A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Mor. CP 62210 (Mexico); Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, 62580 Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad, UPCH, Tuxtla Gutierrez, Chiapas (Mexico)


    High purity hydrogen was generated from the chemical reaction of aluminum and sodium hydroxide. The aluminum used in this study was obtained from empty soft drink cans and treated with concentrated sulfuric acid to remove the paint and plastic film. One gram of aluminum was reacted with a solution of 2moldm{sup -3} of sodium hydroxide to produce hydrogen. The hydrogen produced from aluminum cans and oxygen obtained from a proton exchange membrane electrolyzer or air, was fed to a proton exchange membrane (PEM) fuel cell to produce electricity. Yields of 44 mmol of hydrogen contained in a volume of 1.760dm{sup 3} were produced from one gram of aluminum in a time period of 20 min. (author)

  17. Influence of Elemental Iron on Hydrogen Content in Superheated Aluminum-iron Melts

    Institute of Scientific and Technical Information of China (English)

    HU Li-na; BIAN Xiu-fang; ANANDA Mahto; DUAN You-feng


    The hydrogen content in liquid binary aluminum alloys with 1,3,5 and 8 wt% iron has been determined in the temperature range from 973K to 1103K.The hydrogen content in molten Al-Fe alloys increases remarkably when the temperature of the melt rises to about 1053K.This work indicates that the alloying element iron plays an important role in hydrogen content in superheated Al-Fe alloy melts below about 1053K.The results make it clear that the hydrogen content in the melt aluminum reduces with the increasing element levels.A conclusion is drawn that the degree of gassing in molten Al-Fe alloys is bound up with the properties of oxide film of aluminum alloy melts.The element iron has no effect on the compact structure of oxide film in aluminum melts.The effects of alloying element are theoretically analyzed in terms of Wagner interaction parameter.According to the values of the first order interaction parameter,it is concluded that the interaction between iron atom and aluminum is much stronger than that between hydrogen atom and aluminum,and the addition of the alloying element decreases the affinity of liquid aluminum for hydrogen.

  18. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy

    Directory of Open Access Journals (Sweden)

    Sun Qian


    Full Text Available Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.

  19. Hydrogen absorption in solid aluminum during high-temperature steam oxidation (United States)

    Andreev, L. A.; Gelman, B. G.; Zhukhovitskiy, A. A.


    Hydrogen is emitted by aluminum heated in a vacuum after high-temperature steam treatment. Wire samples are tested for this effect, showing dependence on surface area. Two different mechanisms of absorption are inferred, and reactions deduced.

  20. Qijiang Plans to Build 50 Billion Yuan Industrial Cluster for Transport-use Aluminum

    Institute of Scientific and Technical Information of China (English)


    The reporter learned from the China International Transport-use Aluminum Forum2015 that 5 years later Qijiang District is expected to develop transport-use aluminum industrial cluster with annual output of 50billion yuan.According to statistics,last year 1 in every 9automobile OEM manufacturers nationwide

  1. Nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tashlykova-Bushkevich, Iya I. [Belarusian State University of Informatics and Radioelectronics, Minsk (Belarus)


    The present work summarizes recent progress in the investigation of nanoscale microstructure effects on hydrogen behavior in rapidly solidified aluminum alloys foils produced at exceptionally high cooling rates. We focus here on the potential of modification of hydrogen desorption kinetics in respect to weak and strong trapping sites that could serve as hydrogen sinks in Al materials. It is shown that it is important to elucidate the surface microstructure of the Al alloy foils at the submicrometer scale because rapidly solidified microstructural features affect hydrogen trapping at nanostructured defects. We discuss the profound influence of solute atoms on hydrogen−lattice defect interactions in the alloys. with emphasis on role of vacancies in hydrogen evolution; both rapidly solidified pure Al and conventionally processed aluminum samples are considered.




    Fast ionic clusters Hn+ interact with matter in a specific way which is observed to deviate strongly from the interaction of atomic ions at the same velocity. We present some results obtained at Lyon about foil and gas interactions of hydrogen clusters (5 ≤ n ≤ 23) at projectile velocities close to the Bohr velocity, i.e. dynamics of the cluster fragmentation, charge state of atomic fragments and absolute dissociation cross sections in gas. We also discuss future experiments specially at high...

  3. Precipitation hardening and hydrogen embrittlement of aluminum alloy AA7020

    Indian Academy of Sciences (India)

    Santosh Kumar; T K G Namboodhiri


    AA7020 Al–Mg–Zn, a medium strength aluminium alloy, is used in welded structures in military and aerospace applications. As it may be subjected to extremes of environmental exposures, including high pressure liquid hydrogen, it could suffer hydrogen embrittlement. Hydrogen susceptibility of alloy AA7020 was evaluated by slow strain-rate tensile testing, and delayed failure testing of hydrogen-charged specimens of air-cooled, duplexaged, and water-quenched duplex agedmaterials. The resistance to hydrogen embrittlement of the alloy was found to be in the order of air-cooled duplex aged alloy > as-received (T6 condition) > water quenched duplex aged material.

  4. New nanomaterials for hydrogen storage. A new class of aluminum hydrides; Neue Nanomaterialien zur Wasserstoffspeicherung. Eine neue Klasse von Aluminiumhydriden

    Energy Technology Data Exchange (ETDEWEB)

    Cordes, Joern


    In this work, Aluminum was vaporized in a PACIS cluster source, while molecular Hydrogen was also provided, thus producing Aluminum hydride clusters. These clusters were mass selected and investigated via Photoelectron Spectroscopy with anions in order to determine their electronic structure. In a cooperation with Puru Jena et al. at the Virginia Commonwealth University, electronic and geometric structures of the clusters were also calculated using Density Functional Theory. A group of clusters, specifically Al{sub 4}H{sub 4}, Al{sub 4}H{sub 6} and a series of clusters Al{sub n}H{sub n+2} (5 {<=} n {<=} 8) showed large HOMO-LUMO-Gaps and relatively small adiabatic electron affinities, hinting towards an increased stability of these clusters. The resemblance of the structures of already known and stable Boranes (BnHm) led to investigations whether ''Wade's Rules'' could also be applied to the new Alanes Al{sub n}H{sub m}. Comparison of the experimentally found values for the HOMO-LUMO-Gap, Adiabatic electron Affinity and Vertical Detachment Energy with the calculated values led to geometric structures of the ground states that, in case of the clusters Al{sub n}H{sub n+2} (5 {<=} n {<=} 8) follow Wade's (n+1) rule: They adopt hollow, cage-like closo-structures with one terminal Hydrogen atom per Aluminum atom and two additional Hydrogen atoms on bridge-sites. The clusters Al{sub 4}H{sub 4} and Al{sub 4}H{sub 6} have tetrahedron-shaped structures. While Al{sub 4}H{sub 4} is a perfect tetrahedron, Al{sub 4}H{sub 6} adopts a slightly distorted tetrahedral geometry with D{sub 2d} symmetry and two Hydrogen atoms on bridge sites. Furthermore, Al{sub 4}H{sub 6} showed the biggest HOMO-LUMO-Gap of all investigated clusters with a value of 1.9 {+-} 0.1 eV. These findings seem to contradict Wade's (n+1) rule, but can be understood in terms of the Polyhedral Skeletal Electron Pair Theory (PSEPT). The molecular orbitals predicted by the PSEPT

  5. Hydrogen-bonded clusters of ferrocenecarboxylic acid on Au(111). (United States)

    Quardokus, Rebecca C; Wasio, Natalie A; Christie, John A; Henderson, Kenneth W; Forrest, Ryan P; Lent, Craig S; Corcelli, Steven A; Kandel, S Alex


    Self-assembled monolayers of ferrocenecarboxylic acid (FcCOOH) contain two fundamental units, both stabilized by intermolecular hydrogen bonding: dimers and cyclic five-membered catemers. At surface coverages below a full monolayer, however, there is a significantly more varied structure that includes double-row clusters containing two to twelve FcCOOH molecules. Statistical analysis shows a distribution of cluster sizes that is sharply peaked compared to a binomial distribution. This rules out simple nucleation-and-growth mechanisms of cluster formation, and strongly suggests that clusters are formed in solution and collapse into rows when deposited on the Au(111) surface.

  6. The formation and structure of the oxide and hydroxide chemisorbed phases at the aluminum surface, and relevance to hydrogen embrittlement (United States)

    Francis, Michael; Kelly, Robert; Neurock, Matthew


    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.

  7. Influence of hydrogen content on the behavior of grain refinement in hypereutectic aluminum-silicon alloy

    Institute of Scientific and Technical Information of China (English)

    Lina Hu; Xiufang Bian; Youfeng Duan


    Dissolved hydrogen is harmful to mechanical properties of refined hypereutectic aluminum-silicon alloys. In the present work, by using a stepped-form mold and the hydrogen-detecting instrument HYSCAN Ⅱ, the relationship between the initial hydrogen content in the melt and the refinement effect on the casting of hypereutectic aluminum-silicon alloy was investigated. The experimental results show that the cooling rate, the hydrogen content and the grain refinement effect are three interactive factors. When the hydrogen content is above 0.20 mL/100 g and the cooling rate is lower than that in 50 mm-thick step, hydrogen dissolved in the alloy melt influences the grain refinement effect. With increasing the cooling rate, the critical hydrogen content increases too. It is expected that much hydrogen in the melt make the net interfacial energy larger than or equal to zero, resulting in the shielding of the particles AlP during solidification and that the critical gas content is closely related to the critical radius of embryo bubbles.


    Energy Technology Data Exchange (ETDEWEB)

    Zidan, R; Christopher Fewox, C; Brenda Garcia-Diaz, B; Joshua Gray, J


    Hydrogen storage is one of the challenges to be overcome for implementing the ever sought hydrogen economy. Here we report a novel cycle to reversibly form high density hydrogen storage materials such as aluminium hydride. Aluminium hydride (AlH{sub 3}, alane) has a hydrogen storage capacity of 10.1 wt% H{sub 2}, 149 kg H{sub 2}/m{sup 3} volumetric density and can be discharged at low temperatures (< 100 C). However, alane has been precluded from use in hydrogen storage systems because of the lack of practical regeneration methods. The direct hydrogenation of aluminium to form AlH{sub 3} requires over 10{sup 5} bars of hydrogen pressure at room temperature and there are no cost effective synthetic means. Here we show an unprecedented reversible cycle to form alane electrochemically, using alkali metal alanates (e.g. NaAlH{sub 4}, LiAlH{sub 4}) in aprotic solvents. To complete the cycle, the starting alanates can be regenerated by direct hydrogenation of the dehydrided alane and the alkali hydride being the other compound formed in the electrochemical cell. The process of forming NaAlH{sub 4} from NaH and Al is well established in both solid state and solution reactions. The use of adducting Lewis bases is an essential part of this cycle, in the isolation of alane from the mixtures of the electrochemical cell. Alane is isolated as the triethylamine (TEA) adduct and converted to pure, unsolvated alane by heating under vacuum.

  9. Effects of Aluminum on Hydrogen Solubility and Diffusion in Deformed Fe-Mn Alloys

    Directory of Open Access Journals (Sweden)

    C. Hüter


    Full Text Available We discuss hydrogen diffusion and solubility in aluminum alloyed Fe-Mn alloys. The systems of interest are subjected to tetragonal and isotropic deformations. Based on ab initio modelling, we calculate solution energies and then employ Oriani’s theory which reflects the influence of Al alloying via trap site diffusion. This local equilibrium model is complemented by qualitative considerations of Einstein diffusion. Therefore, we apply the climbing image nudged elastic band method to compute the minimum energy paths and energy barriers for hydrogen diffusion. Both for diffusivity and solubility of hydrogen, we find that the influence of the substitutional Al atom has both local chemical and nonlocal volumetric contributions.

  10. Influence of element Cu on hydrogen content in superheated aluminum melt

    Institute of Scientific and Technical Information of China (English)


    The hydrogen content in molten Al-Cu alloy increases remarkably when the temperature of the melt rises to about 780  ℃. The effects of alloying element are theoretically analyzed in terms of Wagner interaction parameter. Furthermore, analyses indicate that the alloy element Cu plays an important role in the hydrogen content in superheated Al-Cu alloy melt below about 780  ℃. The conclusion is drawn that the degree of gassing in molten Al-Cu alloy is bound up with the properties of oxide film of Al alloy melts. The results make it clear that the hydrogen content in the molten aluminum reduces with increasing element Cu dissolved in aluminum melts at the same temperature.

  11. Interaction of hydrogen with palladium clusters deposited on graphene

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Julio A.; Granja, Alejandra; Cabria, Iván; López, María J. [Departamento de Física Teórica, Atómica y Optica, Universidad de Valladolid, 47011 Valladolid (Spain)


    Hydrogen adsorption on nanoporous carbon materials is a promising technology for hydrogen storage. However, pure carbon materials do not meet the technological requirements due to the week binding of hydrogen to the pore walls. Experimental work has shown that doping with Pd atoms and clusters enhances the storage capacity of porous carbons. Therefore, we have investigated the role played by the Pd dopant on the enhancement mechanisms. By performing density functional calculations, we have found that hydrogen adsorbs on Pd clusters deposited on graphene following two channels, molecular adsorption and dissociative chemisorption. However, desorption of Pd-H complexes competes with desorption of hydrogen, and consequently desorption of Pd-H complexes would spoil the beneficial effect of the dopant. As a way to overcome this difficulty, Pd atoms and clusters can be anchored to defects of the graphene layer, like graphene vacancies. The competition between molecular adsorption and dissociative chemisorption of H{sub 2} on Pd{sub 6} anchored on a graphene vacancy has been studied in detail.

  12. A Density Functional Study of Bare and Hydrogenated Platinum Clusters

    CERN Document Server

    Sebetci, A


    We perform density functional theory calculations using Gaussian atomic-orbital methods within the generalized gradient approximation for the exchange and correlation to study the interactions in the bare and hydrogenated platinum clusters. The minimum-energy structures, binding energies, relative stabilities, vibrational frequencies and the highest occupied and lowest unoccupied molecular-orbital gaps of Pt_nH_m (n=1-5, m=0-2) clusters are calculated and compared with previously studied pure platinum and hydrogenated platinum clusters. We investigate any magic behavior in hydrogenated platinum clusters and find that Pt_4H_2 is more stable than its neighboring sizes. Our results do not agree with a previous conclusion that 3D geometries of Pt tetramer and pentamer are unfavored. On the contrary, the lowest energy structure of Pt_4 is found to be a distorted tetrahedron and that of Pt_5 is found to be a bridge site capped tetrahedron which is a new global minimum for Pt_5 cluster. The successive addition of H ...

  13. Electrocoagulation of palm oil mill effluent as wastewater treatment and hydrogen production using electrode aluminum. (United States)

    Nasution, M Ansori; Yaakob, Z; Ali, Ehsan; Tasirin, S M; Abdullah, S R S


    Palm oil mill effluent (POME) is highly polluting wastewater generated from the palm oil milling process. Palm oil mill effluent was used as an electrolyte without any additive or pretreatment to perform electrocoagulation (EC) using electricity (direct current) ranging from 2 to 4 volts in the presence of aluminum electrodes with a reactor volume of 20 L. The production of hydrogen gas, removal of chemical oxygen demand (COD), and turbidity as a result of electrocoagulation of POME were determined. The results show that EC can reduce the COD and turbidity of POME by 57 and 62%, respectively, in addition to the 42% hydrogen production. Hydrogen production was also helpful to remove the lighter suspended solids toward the surface. The production of Al(OH)XHO at the aluminum electrode (anode) was responsible for the flocculation-coagulation process of suspended solids followed by sedimentation under gravity. The production of hydrogen gas from POME during EC was also compared with hydrogen gas production by electrolysis of tap water at pH 4 and tap water without pH adjustment under the same conditions. The main advantage of this study is to produce hydrogen gas while treating POME with EC to reduce COD and turbidity effectively.

  14. Modeling the Hydrogen Solubility in Liquid Aluminum Alloys (United States)

    Harvey, Jean-Philippe; Chartrand, Patrice


    The modeling of hydrogen solubility in multicomponent Al-(Li, Mg, Cu, and Si) liquid phase has been performed with a thermodynamic approach using the modified quasichemical model with the pair approximation (MQMPA). All hydrogen solubility data available in literature was assessed critically to obtain the binary parameters of the MQMPA model for the Al-H, Li-H, Mg-H, Cu-H, Zn-H, and Si-H melts. For the Li-H system, a new thermodynamic description of the stable solid lithium hydride was determined based on the c p found in literature. The thermodynamic model for the Al-Li system also was reassessed in this work to take into account the short-range ordering observed for this system. Built-in interpolation techniques allow the model to estimate the thermodynamic properties of the multicomponent liquid solution from the liquid model parameters of the lower order subsystems. A comparison of the calculated hydrogen solubility performed at various equilibrium conditions of temperature, pressure, and composition with the available experimental data found in the literature is presented in this work, as well as a comparison with some results from previous modeling.

  15. Aluminum Cluster-Based Materials for Propulsion and Other Applications (United States)


    covalent bonds, and have made headways towards synthesis of cluster nanoassemblies and their characterization. We demonstrated that the and selective catalysis. In collaboration with Castleman’s group, we investigated these potential building blocks of nanoassemblies and their

  16. Remarkable Hydrogen Storage on Beryllium Oxide Clusters: First Principles Calculations

    CERN Document Server

    Shinde, Ravindra


    Since the current transportation sector is the largest consumer of oil, and subsequently responsible for major air pollutants, it is inevitable to use alternative renewable sources of energies for vehicular applications. The hydrogen energy seems to be a promising candidate. To explore the possibility of achieving a solid-state high-capacity storage of hydrogen for onboard applications, we have performed first principles density functional theoretical calculations of hydrogen storage properties of beryllium oxide clusters (BeO)$_{n}$ (n=2 -- 8). We observed that polar BeO bond is responsible for H$_{2}$ adsorption. The problem of cohesion of beryllium atoms does not arise, as they are an integral part of BeO clusters. The (BeO)$_{n}$ (n=2 -- 8) adsorbs 8--12 H$_{2}$ molecules with an adsorption energy in the desirable range of reversible hydrogen storage. The gravimetric density of H$_{2}$ adsorbed on BeO clusters meets the ultimate 7.5 wt% limit, recommended for onboard practical applications. In conclusion,...

  17. Revealing the multi-bonding state between hydrogen and graphene-supported Ti clusters

    CERN Document Server

    Takahashi, Keisuke; Omori, Kengo; Mashoff, Torge; Convertino, Domenica; Miseikis, Vaidotas; Coletti, Camilla; Tozzini, Valentina; Heun, Stefan


    Hydrogen adsorption on graphene-supported metal clusters has brought much controversy due to the complex nature of the bonding between hydrogen and metal clusters. The bond types of hydrogen and graphene-supported Ti clusters are experimentally and theoretically investigated. Transmission electron microscopy shows that Ti clusters of nanometer-size are formed on graphene. Thermal desorption spectroscopy captures three hydrogen desorption peaks from hydrogenated graphene-supported Ti clusters. First principle calculations also found three types of interaction: Two types of bonds with different partial ionic character and physisorption. The physical origin for this rests on the charge state of the Ti clusters: when Ti clusters are neutral, H2 is dissociated, and H forms bonds with the Ti cluster. On the other hand, H2 is adsorbed in molecular form on positively charged Ti clusters, resulting in physisorption. Thus, this work clarifies the bonding mechanisms of hydrogen on graphene-supported Ti clusters.

  18. Orientationally ordered ridge structures of aluminum films on hydrogen terminated silicon

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Pantleon, Karen


    Films of aluminum deposited onto Si(100) substrates show a surface structure of parallel ridges. On films deposited on oxidized silicon substrates the direction of the ridges is arbitrary, but on films deposited on hydrogen-terminated Si(100) the ridges are oriented parallel to the < 110 > direct......Films of aluminum deposited onto Si(100) substrates show a surface structure of parallel ridges. On films deposited on oxidized silicon substrates the direction of the ridges is arbitrary, but on films deposited on hydrogen-terminated Si(100) the ridges are oriented parallel to the ... > directions on the silicon substrate. The ridge structure appears when the film thickness is above 500 nm, and increasing the film thickness makes the structure more distinct. Anodic oxidation enhances the structure even further. X-ray diffraction indicates that grains in the film have mostly (110) facets...

  19. Chemical Hydrogen Storage Using Polyhedral Borane Anions and Aluminum-Ammonia-Borane Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Hawthorne, M. Frederick; Jalisatgi, Satish S.; Safronov, Alexander V.; Lee, Han Beak; Wu, Jianguo


    Phase 1. Hydrolysis of borohydride compounds offer the potential for significant hydrogen storage capacity, but most work to date has focused on one particular anion, BH4-, which requires high pH for stability. Other borohydride compounds, in particular polyhedral borane anions offer comparable hydrogen storage capacity without requiring high pH media and their long term thermal and hydrolytic stability coupled with non-toxic nature make them a very attractive alternative to NaBH4. The University of Missouri project provided the overall program focal point for the investigation of catalytic hydrolysis of polyhedral borane anions for hydrogen release. Due to their inherent stability, a transition metal catalyst was necessary for the hydrolysis of polyhedral borane anions. Transition metal ions such as cobalt, nickel, palladium and rhodium were investigated for their catalytic activity in the hydrolysis of nido-KB11H14, closo-K2B10H10, and closo-K2B12H12. The rate of hydrolysis follows first-order kinetics with respect to the concentration of the polyhedral borane anion and surface area of the rhodium catalyst. The rate of hydrolysis depends upon a) choice of polyhedral borane anion, c) concentration of polyhedral borane anion, d) surface area of the rhodium catalyst and e) temperature of the reaction. In all cases the yield of hydrogen was 100% which corresponds to ~7 wt% of hydrogen (based on material wt%). Phase 2. The phase 2 of program at the University of Missouri was focused upon developing aluminum ammonia-boranes (Al-AB) as chemical hydrogen storage materials, specifically their synthesis and studies of their dehydrogenation. The ammonia borane molecule (AB) is a demonstrated source of chemically stored hydrogen (19.6 wt%) which meets DOE performance parameters except for its regeneration from spent AB and elemental hydrogen. The presence of an aluminum center bonded to multiple AB residues might combine the efficiency of AB dehydrogenation with an aluminum

  20. Model study in chemisorption: atomic hydrogen on beryllium clusters

    Energy Technology Data Exchange (ETDEWEB)

    Bauschlicher, C.W. Jr.


    The interaction between atomic hydrogen and the (0001) surface of Be metal has been studied by ab initio electronic structure theory. Self-consistent-field (SCF) calculations have been performed using minimum, optimized minimum, double zeta and mixed basis sets for clusters as large as 22 Be atoms. The binding energy and equilibrium geometry (the distance to the surface) were determined for 4 sites. Both spatially restricted (the wavefunction was constrained to transform as one of the irreducible representations of the molecular point group) and unrestricted SCF calculations were performed. Using only the optimized minimum basis set, clusters containing as many as 22 beryllium atoms have been investigated. From a variety of considerations, this cluster is seen to be nearly converged within the model used, providing the most reliable results for chemisorption. The site dependence of the frequency is shown to be a geometrical effect depending on the number and angle of the bonds. The diffusion of atomic hydrogen through a perfect beryllium crystal is predicted to be energetically unfavorable. The cohesive energy, the ionization energy and the singlet-triplet separation were computed for the clusters without hydrogen. These quantities can be seen as a measure of the total amount of edge effects. The chemisorptive properties are not related to the total amount of edge effects, but rather the edge effects felt by the adsorbate bonding berylliums. This lack of correlation with the total edge effects illustrates the local nature of the bonding, further strengthening the cluster model for chemisorption. A detailed discussion of the bonding and electronic structure is included. The remaining edge effects for the Be/sub 22/ cluster are discussed.

  1. Hydrogen-environment-assisted cracking of an aluminum-zinc-magnesium(copper) alloy (United States)

    Young, George Aloysius, Jr.

    There is strong evidence to indicate that hydrogen embrittlement plays a significant, if not controlling, role in the environmentally assisted cracking of 7XXX series aluminum alloys. In order to better understand hydrogen environment assisted cracking (HEAC), crack growth rate tests in the K-independent stage II crack growth regime were conducted on fracture mechanics specimens of an Al-6.09Zn-2.14Mg-2.19Cu alloy (AA 7050) and a low copper variant (Al-6.87Zn-2.65Mg-0.06Cu). Crack growth rate tests were performed in 90% relative humidity (RH) air between 25 and 90°C to assure hydrogen embrittlement control. The underaged, peak aged, and overaged tempers were investigated. Hydrogen uptake in humid air, hydrogen diffusion, and hydrogen trapping were investigated for each temper. Lastly, near crack tip hydrogen concentration depth profiles were analyzed via nuclear reaction analysis (NRA) and secondary ion mass spectroscopy (SIMS) using a liquid gallium, focused ion beam sputtering source (FIB/SIMS). The results of this study help explain and quantify empirically known trends concerning HEAC resistance and also establish new findings. In the copper bearing alloy, overaged tempers are more resistant but not immune to HEAC. Humid air is an aggressive environment for Al-Zn-Mg alloys because water vapor reacts with bare aluminum to produce high surface concentrations of hydrogen. This occurs in all tempers. Hydrogen diffuses from the near surface region to the high triaxial stress region ahead of the crack tip and collects at the high angle grain boundaries. The combination of tensile stress and high hydrogen concentration at the grain boundaries then causes intergranular fracture. Crack extension bares fresh metal and the process of hydrogen production, uptake, diffusion to the stressed grain boundary, and crack extension repeats. One reason increased degree of aging improves HEAC resistance in copper bearing 7XXX series alloys is that volume lattice and effective

  2. Thermal behavior of a 13-molecule hydrogen cluster under pressure. (United States)

    Santamaria, Rubén; Soullard, Jacques; Jellinek, Julius


    The thermal behavior of a 13-molecule hydrogen cluster is studied as a function of pressure and temperature using a combination of trajectory and density functional theory simulations. The analysis is performed in terms of characteristic descriptors such as caloric curve, root-mean-square bond length fluctuation, pair correlation function, velocity autocorrelation function, volume thermal expansion, and diffusion coefficients. The discussion addresses on the peculiarities of the transition from the ordered-to-disordered state as exhibited by the cluster under different pressures and temperatures.

  3. The Oxidation Products of Aluminum Hydride and Boron Aluminum Hydride Clusters (United States)


    diborane, hydrogen, and a white solid. Whatley et al.8 studied the products of diborane oxidation. Roth and co-workers9 found HOBO to be the main...product during the oxidation of diborane. Roth and Bauer10 proposed that the formation of HOBO severely inhibits the oxidation of boranes by breaking...Whatley and R. N . Pease, J. Am. Chem. Soc, 76, 1997 (1954). 9 W. Roth and W. H. Bauer, J. Phys. Chem, 60, 639 (1956). 10 W. Roth , and W. H. Bauer

  4. Low Temperature Curing of Hydrogen Silsesquioxane Surface Coatings for Corrosion Protection of Aluminum

    DEFF Research Database (Denmark)

    Lampert, Felix; Jensen, Annemette Hindhede; Møller, Per


    Hydrogen Silsesquioxane (HSQ) has shown to be a promising precursor for corrosion protective glass coatings for metallic substrates due to the excellent barrier properties of the films, especially in the application of protective coatings for aluminum in the automotive industry where high chemical...... stability in alkaline environments is required. The coatings have been successfully applied to stainless steel substrates. However the traditional thermal curing of HSQ involves heating to elevated temperatures, which are beyond those applicable for most industrial applications of aluminum. In this study...... low temperature processes are tested and evaluated as possible alternatives to the traditional high temperature cure. Thin HSQ films are deposited onsilicon wafers to model the degree of curing induced by the low temperature methods in comparison to thermal curing.Furthermore, the coatings are applied...

  5. Excited electronic state decomposition mechanisms of clusters of dimethylnitramine and aluminum

    Indian Academy of Sciences (India)

    Anupam Bera; Atanu Bhattacharya


    In this report, electronically non-adiabatic decomposition pathways of clusters of dimethylnitramine and aluminum (DMNA-Al and DMNA-Al2) are discussed in comparison to isolated dimethylnitramine (DMNA). Electronically excited state processes of DMNA-Al and DMNA-Al2 are explored using the complete active space self-consistent field (CASSCF) and the restricted active space self-consistent field (RASSCF) theories, respectively. Similar to the nitro-nitrite isomerization reaction pathway of DMNA, DMNA-Al clusters also exhibit isomerization pathway. However, it involves several other steps, such as, first Al-O bond dissociation, then N-N bond dissociation followed by isomerization and finally NO elimination. Furthermore, DMNA-Al clusters exhibit overall exothermic decomposition reaction pathway and isolated DMNA shows overall endothermic reaction channel.

  6. Path integral molecular dynamics simulation of solid para-hydrogen with an aluminum impurity (United States)

    Mirijanian, Dina T.; Alexander, Millard H.; Voth, Gregory A.


    The equilibrium properties of an aluminum impurity trapped in solid para-hydrogen have been studied. The results were compared to those of a previous study by Krumrine et al. [J. Chem. Phys. 113 (2000) 9079] with an atomic boron. In the presence of vacancy defect, when the orientation-dependent Al- pH 2 potential is used, the Al atom is displaced to a position half way between its original substituted site and the vacancy site. Thermodynamic results also indicate that the presence of a neighboring vacancy helps to stabilize the Al impurity to a far greater extent than in the case of the B impurity.

  7. Enhanced conductivity of aluminum doped ZnO films by hydrogen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Chang, H.P. [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Wang, F.H., E-mail: [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Wu, J.Y.; Kung, C.Y.; Liu, H.W. [Department of Electrical Engineering and Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)


    Aluminum doped zinc oxide (AZO) thin films prepared by radio-frequency (RF) magnetron sputtering at various RF power were treated by hydrogen plasma to enhance the characteristics for transparent electrode applications. The hydrogen plasma treatment was carried out at 300 {sup o}C in a plasma enhanced chemical vapor deposition system. X-ray diffraction analysis shows that all AZO films have a (002) preferred orientation and film crystallinity seems no significant change after plasma treatment. The plasma treatment not only significantly decreases film resistivity but enhances electrical stability as aging in air ambient. The improved electrical properties are due to desorption of weakly bonded oxygen species, formation of Zn-H type species and passivation of deep-level defects during plasma treatment.

  8. A halo model for cosmological neutral hydrogen : abundances and clustering

    CERN Document Server

    Padmanabhan, Hamsa; Amara, Adam


    We extend the results of previous analyses towards constraining the abundance and clustering of post-reionization ($z \\sim 0-5$) neutral hydrogen (HI) systems using a halo model framework. We work with a comprehensive HI dataset including the small-scale clustering, column density and mass function of HI galaxies at low redshifts, intensity mapping measurements at intermediate redshifts and the UV/optical observations of Damped Lyman Alpha (DLA) systems at higher redshifts. We use a Markov Chain Monte Carlo (MCMC) approach to constrain the parameters of the best-fitting models, both for the HI-halo mass relation and the HI radial density profile. We find that a radial exponential profile results in a good fit to the low-redshift HI observations, including the clustering and the column density distribution. The form of the profile is also found to match the high-redshift DLA observations, when used in combination with a three-parameter HI-halo mass relation and a redshift evolution in the HI concentration. The...

  9. Determination of iron and aluminum based on the catalytic effect on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate


    Cai, Longfei; Xu, Chunxiu


    A simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry is presented. This method is based on the catalytic effects of iron and aluminum on the reaction of xylene cyanol FF with hydrogen peroxide and potassium periodate. Both iron and aluminum did not show catalytic effects on the oxidation reaction of xylene cyanol FF in the presence of either hydrogen peroxide or potassium periodate. However, significant catalytic...

  10. Improved conductivity of aluminum-doped ZnO: The effect of hydrogen diffusion from a hydrogenated amorphous silicon capping layer

    NARCIS (Netherlands)

    Ponomarev, M. V.; Sharma, K.; Verheijen, M. A.; M. C. M. van de Sanden,; Creatore, M.


    Plasma-deposited aluminum-doped ZnO (ZnO:Al) demonstrated a resistivity gradient as function of the film thickness, extending up to about 600 nm. This gradient decreased sharply when the ZnO:Al was capped by a hydrogenated amorphous silicon layer (a-Si:H) and subsequently treated according to the so

  11. Peri-nuclear clustering of mitochondria is triggered during aluminum maltolate induced apoptosis. (United States)

    Dewitt, David A; Hurd, Jennifer A; Fox, Nena; Townsend, Brigitte E; Griffioen, Kathleen J S; Ghribi, Othman; Savory, John


    Synapse loss and neuronal death are key features of Alzheimer's disease pathology. Disrupted axonal transport of mitochondria is a potential mechanism that could contribute to both. As the major producer of ATP in the cell, transport of mitochondria to the synapse is required for synapse maintenance. However, mitochondria also play an important role in the regulation of apoptosis. Investigation of aluminum (Al) maltolate induced apoptosis in human NT2 cells led us to explore the relationship between apoptosis related changes and the disruption of mitochondrial transport. Similar to that observed with tau over expression, NT2 cells exhibit peri-nuclear clustering of mitochondria following treatment with Al maltolate. Neuritic processes largely lacked mitochondria, except in axonal swellings. Similar, but more rapid results were observed following staurosporine administration, indicating that the clustering effect was not specific to Al maltolate. Organelle clustering and transport disruption preceded apoptosis. Incubation with the caspase inhibitor zVAD-FMK effectively blocked apoptosis, however failed to prevent organelle clustering. Thus, transport disruption is associated with the initiation, but not necessarily the completion of apoptosis. These results, together with observed transport defects and apoptosis related changes in Alzheimer disease brain suggest that mitochondrial transport disruption may play a significant role in synapse loss and thus the pathogenesis or Alzheimer's disease.

  12. Pahs, Ionized Gas, and Molecular Hydrogen in Brightest Cluster Galaxies of Cool Core Clusters of Galaxies

    CERN Document Server

    Donahue, Megan; O'Connell, Robert W; Voit, G Mark; Hoffer, Aaron; McNamara, Brian R; Nulsen, Paul E J


    We present measurements of 5-25 {\\mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of 9 cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally-excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H2 rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as ...

  13. Asymmetric partitioning of metals among cluster anions and cations generated via laser ablation of mixed aluminum/Group 6 transition metal targets. (United States)

    Waller, Sarah E; Mann, Jennifer E; Jarrold, Caroline Chick


    While high-power laser ablation of metal alloys indiscriminately produces gas-phase atomic ions in proportion to the abundance of the various metals in the alloy, gas-phase ions produced by moderate-power laser ablation sources coupled with molecular beams are formed by more complicated mechanisms. A mass spectrometric study that directly compares the mass distributions of cluster anions and cations generated from laser ablation of pure aluminum, an aluminum/molybdenum mixed target, and an aluminum/tungsten mixed target is detailed. Mass spectra of anionic species generated from the mixed targets showed that both tungsten and molybdenum were in higher abundance in the negatively charged species than in the target material. Mass spectra of the cationic species showed primarily Al(+) and aluminum oxide and hydroxide cluster cations. No molybdenum- or tungsten-containing cluster cations were definitively assigned. The asymmetric distribution of aluminum and Group 6 transition metals in cation and anion cluster composition is attributed to the low ionization energy of atomic aluminum and aluminum suboxide clusters. In addition, the propensity of both molybdenum and tungsten to form metal oxide cluster anions under the same conditions that favor metallic aluminum cluster anions is attributed to differences in the optical properties of the surface oxide that is present in the metal powders used to prepare the ablation targets. Mechanisms of mixed metal oxide clusters are considered.

  14. Bubble growth from clustered hydrogen and helium atoms in tungsten under a fusion environment (United States)

    You, Yu-Wei; Kong, Xiang-Shan; Wu, Xuebang; Liu, C. S.; Chen, J. L.; Luo, G.-N.


    Bubbles seriously degrade the mechanical properties of tungsten and thus threaten the safety of nuclear fusion devices, however, the underlying atomic mechanism of bubble growth from clustered hydrogen and helium atoms is still mysterious. In this work, first-principles calculations are therefore carried out to assess the stability of tungsten atoms around both hydrogen and helium clusters. We find that the closest vacancy-formation energies of interstitial hydrogen and helium clusters are substantially decreased. The first-nearest and second-nearest vacancy-formation energies close to vacancy-hydrogen clusters decrease in a step-like way to  ˜0, while those close to vacancy-helium clusters are reduced almost linearly to  ˜-5.46 eV when atom number reaches 10. The vacancy-formation energies closest to helium clusters are more significantly reduced than those nearest to hydrogen clusters, whatever the clusters are embedded at interstitial sites or vacancies. The reduction of vacancy-formation energies results in instability and thus emission of tungsten atoms close to interstitial helium and vacancy-helium clusters, which illustrates the experimental results, that the tungsten atoms can be emitted from the vicinity of vacancy-helium clusters. In addition, the emission of unstable tungsten atoms close to hydrogen clusters may become possible once they are disturbed by the environment. The emission of tungsten atoms facilitates the growth and evolution of hydrogen and helium clusters and ultimately the bubble formation. The results also explain the bubble formation even if no displacement damage is produced in tungsten exposed to low-energy hydrogen and helium plasma.

  15. NMR properties of hydrogen-bonded glycine cluster in gas phase (United States)

    Carvalho, Jorge R.; da Silva, Arnaldo Machado; Ghosh, Angsula; Chaudhuri, Puspitapallab


    Density Functional Theory (DFT) calculations have been performed to study the effect of the hydrogen bond formation on the Nuclear Magnetic Resonance (NMR) parameters of hydrogen-bonded clusters of glycine molecules in gas-phase. DFT predicted isotropic chemical shifts of H, C, N and O of the isolated glycine with respect to standard reference materials are in reasonable agreement with available experimental data. The variations of isotropic and anisotropic chemical shifts for all atoms constituting these clusters containing up to four glycine molecules have been investigated systematically employing gradient corrected hybrid B3LYP functional with three different types of extended basis sets. The clusters are mainly stabilized by a network of strong hydrogen bonds among the carboxylic (COOH) groups of glycine monomers. The formation of hydrogen bond influences the molecular structure of the clusters significantly which, on the other hand, gets reflected in the variations of NMR properties. The carbon (C) atom of the sbnd COOH group, the bridging hydrogen (H) and the proton-donor oxygen (O) atom of the Osbnd H bond suffer downfield shift due to the formation of hydrogen bond. The hydrogen bond lengths and the structural complexity of the clusters are found to vary with the number of participating monomers. A direct correlation between the hydrogen bond length and isotropic chemical shift of the bridging hydrogen is observed in all cases. The individual variations of the principal axis elements in chemical shift tensor provide additional insight about the different nature of the monomers within the cluster.

  16. A Dark Hydrogen Cloud in the Virgo Cluster

    CERN Document Server

    Minchin, R; Disney, M; Boyce, P; García, D; Jordan, C; Kilborn, V; Lang, R; Roberts, S; Sabatini, S; Van Driel, W; Minchin, Robert; Davies, Jonathan; Disney, Michael; Boyce, Peter; Garcia, Diego; Jordan, Christine; Kilborn, Virginia; Lang, Robert; Roberts, Sarah; Sabatini, Sabina; Driel, Wim van


    VIRGOHI21 is an HI source detected in the Virgo Cluster survey of Davies et al. (2004) which has a neutral hydrogen mass of 10^8 M_solar and a velocity width of Delta V_20 = 220 km/s. From the Tully-Fisher relation, a galaxy with this velocity width would be expected to be 12th magnitude or brighter; however deep CCD imaging has failed to turn up a counterpart down to a surface-brightness level of 27.5 B mag/sq. arcsec. The HI observations show that it is extended over at least 16 kpc which, if the system is bound, gives it a minimum dynamical mass of ~10^11 M_solar and a mass to light ratio of M_dyn/L_B > 500 M_solar/L_solar. If it is tidal debris then the putative parents have vanished; the remaining viable explanation is that VIRGOHI21 is a dark halo that does not contain the expected bright galaxy. This object was found because of the low column density limit of our survey, a limit much lower than that achieved by all-sky surveys such as HIPASS. Further such sensitive surveys might turn up a significant n...

  17. Quantum simulations of the hydrogen molecule on ammonia clusters (United States)

    Mella, Massimo; Curotto, E.


    Mixed ammonia-hydrogen molecule clusters [H2-(NH3)n] have been studied with the aim of exploring the quantitative importance of the H2 quantum motion in defining their structure and energetics. Minimum energy structures have been obtained employing genetic algorithm-based optimization methods in conjunction with accurate pair potentials for NH3-NH3 and H2-NH3. These include both a full 5D potential and a spherically averaged reduced surface mimicking the presence of a para-H2. All the putative global minima for n ⩾ 7 are characterized by H2 being adsorbed onto a rhomboidal ammonia tetramer motif formed by two double donor and two double acceptor ammonia molecules. In a few cases, the choice of specific rhombus seems to be directed by the vicinity of an ammonia ad-molecule. Diffusion Monte Carlo simulations on a subset of the species obtained highlighted important quantum effects in defining the H2 surface distribution, often resulting in populating rhomboidal sites different from the global minimum one, and showing a compelling correlation between local geometrical features and the relative stability of surface H2. Clathrate-like species have also been studied and suggested to be metastable over a broad range of conditions if formed.

  18. Hydrogen spillover on DV (555-777) graphene – vanadium cluster system: First principles study

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, E. Mathan, E-mail:, E-mail:; Thapa, Ranjit, E-mail:, E-mail: [SRM Research Institute, SRM University, Kattankulathur, Tamil Nadu - 603203 (India); P, Sabarikirishwaran [Department of Physics and Nanotechnology, SRM University, Kattankulathur, Tamil Nadu - 603203 (India)


    Using dispersion corrected density functional theory (DFT+D), the interaction of Vanadium adatom and cluster with divacancy (555-777) defective graphene sheet has been studied elaborately. We explore the prospect of hydrogen storage on V{sub 4} cluster adsorbed divacancy graphene system. It has been observed that V{sub 4} cluster (acting as a catalyst) can dissociate the H{sub 2} molecule into H atoms with very low barrier energy. We introduce the spillover of the atomic hydrogen throughout the surface via external mediator gallane (GaH{sub 3}) to form a hydrogenated system.

  19. First principles investigations of small bimetallic PdGa clusters as catalysts for hydrogen dissociation (United States)

    Kaul, Indu; Ghosh, Prasenjit


    Using first principles density functional theory based calculations, we have studied hydrogen dissociation on sub nanometer bimetallic clusters formed from d-block (Pd) and p-block (Ga) elements in gas phase to explore the feasibility of using them as cheap catalysts for hydrogen dissociation. Our calculations show that the dimers, trimers and tetramers of these clusters are thermodynamically more stable than the pure ones for all Ga concentrations. For a given cluster size, we find that the clusters containing equal amount of Pd and Ga are the most stable ones. In contrast to bulk PdGa, the contribution of Pd-d states to the highest occupied molecular orbitals of the bimetallic clusters are either very small or absent. Study of adsorption of hydrogen molecule on these clusters show that hydrogen binds in an activated form only on the Pd rich clusters. From the calculations of hydrogen dissociation barriers on tetramers of pure Pd, 25% Ga (Pd3Ga) and 50% Ga (Pd2Ga2) we find that Pd3Ga is the most efficient catalyst for hydrogen dissociation with barriers even lower than that on the PdGa surfaces.

  20. Generation of Porous Alumina Layers in a Polydimethylsiloxane/Hydrogen Peroxide Medium on Aluminum Substrate in Corona Discharges

    Directory of Open Access Journals (Sweden)

    A. Groza


    Full Text Available The porous alumina (Al2O3 layer obtained at the interface between polydimethylsiloxane/hydrogen peroxide medium and aluminum substrate under charged and neutral species injection produced in negative corona discharges in air at atmospheric pressure is analyzed by different methods in this paper. The scanning electron microscopy investigations showed the uniform distribution of the pores formed in the alumina layer and their columnar structures. Both energy dispersive X-ray spectroscopy (EDS and X-ray photoelectron spectroscopy (XPS measurements indicate that during the anodization process of the aluminum in the polydimethylsiloxane/hydrogen peroxide medium in corona discharge the incorporation of silicon in the structure of the alumina layer is possible.

  1. Semiclassical Szego limit of resonance clusters for the hydrogen atom Stark Hamiltonian

    CERN Document Server

    Hislop, Peter D


    We study the weighted averages of resonance clusters for the hydrogen atom with a Stark electric field in the weak field limit. We prove a semiclassical Szego-type theorem for resonance clusters showing that the limiting distribution of the resonance shifts concentrates on the classical energy surface corresponding to a rescaled eigenvalue of the hydrogen atom Hamiltonian. This result extends Szego-type results on eigenvalue clusters to resonance clusters. There are two new features in this work: first, the study of resonance clusters requires the use of non self-adjoint operators, and second, the Stark perturbation is unbounded so control of the perturbation is achieved using localization properties of coherent states corresponding to hydrogen atom eigenvalues.

  2. Next Generation Energetic Materials: New Cluster Hydrides and Metastable Alloys of Aluminum in Very Low Oxidation States (United States)


    Zavalij, P; Bowen, K.; Schnöckel, H.; Eichhorn, B. Inorganic Chemistry , submitted Jan 2016. 2. “Growth of metalloid aluminum clusters on graphene...organometallic chemistry . ■ REFERENCES (1) (a) Holleman-Wiberg, Inorganic Chemistry ; Academic Press: San Diego, London, 2001. (b)Holleman-Wiberg, Lehrbuch... Chemistry , Johns Hopkins University, Baltimore, Maryland 21218, USA 2Institute of Inorganic Chemistry , Karlsruhe Institute of Technology, 76128 Karlsruhe

  3. Three-dimensional simulation on explosions of hydrogen atomic clusters irradiated by an intense femtosecond laser pulse

    Institute of Scientific and Technical Information of China (English)

    Xia Yong; Liu Jian-Sheng; Ni Guo-Quan; Xu Zhi-Zhan


    Using classic particle dynamics simulations, the interaction process between an intense femtosecond laser pulse and icosahedral hydrogen atomic clusters H13, H55 and H147 has been studied. It is revealed that with increasing number of atoms in the cluster, the kinetic energy of ions generated in the Coulomb explosion of the ionized hydrogen clusters increases. The expansion process of the clusters after laser irradiation has also been examined, showing that the expansion scale decreases with increasing cluster size.

  4. Hydrogen binding effect on charged P2 ( = 1-7) clusters

    Indian Academy of Sciences (India)

    Zhicong Fang; Xiangjun Kuang


    An all-electron (AE) calculation of the hydrogen binding effect on charged phosphorus clusters has been performed under the framework of density functional theory (DFT). Compared with the P$^{\\pm}_{2n}$ ( = 1-7) clusters, the HP$^{\\pm}_{2n}$ ( = 1-7), cluster has shorter average P-P bond length, larger binding energy and HOMOLUMO gap (HLG), higher chemical hardness and frequency of P-P mode. After binding with one hydrogen atom, the electronic structure is changed from open electronic shell to closed electronic shell. Geometrical stability, chemical stability and electronic stability are strengthened. These stability enhancements may be simply understood considering the electron pairing effect.

  5. Reduction of interface states by hydrogen treatment at the aluminum oxide/4H-SiC Si-face interface

    Directory of Open Access Journals (Sweden)

    Hironori Yoshioka


    Full Text Available Processes to form aluminum oxide as a gate insulator on the 4H-SiC Si-face are investigated to eliminate the interface state density (DIT and improve the mobility. Processes that do not involve the insertion or formation of SiO2 at the interface are preferential to eliminate traps that may be present in SiO2. Aluminum oxide was formed by atomic layer deposition with hydrogen plasma pretreatment followed by annealing in forming gas. Hydrogen treatment was effective to reduce DIT at the interface of aluminum oxide and SiC without a SiO2 interlayer. Optimization of the process conditions resulted in DIT for the metal oxide semiconductor (MOS capacitor of 1.7×1012 cm−2eV−1 at 0.2 eV, and the peak field-effect mobility of the MOS field-effect transistor (MOSFET was approximately 57 cm2V−1s−1.

  6. Production of hydrogen in the reaction between aluminum and water in the presence of NaOH and KOH

    Directory of Open Access Journals (Sweden)

    C. B. Porciúncula


    Full Text Available The objective of this work is to investigate the production of hydrogen as an energy source by means of the reaction of aluminum with water. This reaction only occurs in the presence of NaOH and KOH, which behave as catalysts. The main advantages of using aluminum for indirect energy storage are: recyclability, non-toxicity and easiness to shape. Alkali concentrations varying from 1 to 3 mol.L-1 were applied to different metallic samples, either foil (0.02 mm thick or plates (0.5 and 1 mm thick, and reaction temperatures between 295 and 345 K were tested. The results show that the reaction is strongly influenced by temperature, alkali concentration and metal shape. NaOH commonly promotes faster reactions and higher real yields than KOH.

  7. Continuous measurement of peak hydrogen fluoride exposures in aluminum smelter potrooms: instrument development and in-plant evaluation. (United States)

    Dando, Neal; Xu, Weizong; Peace, Jon Nathaniel


    The aluminum smelting process continuously evolves both sulfur dioxide (SO2) and hydrogen fluoride (HF) gases. The vast majority of these evolved gases are captured by local exhaust ventilation systems and transported to fume treatment centers. Any gas escaping the ventilation systems could create the potential for workplace exposures. Currently, there are no commercially available sensors that are capable of selectively measuring peak concentrations (< 10 sec) of HF in the presence of SO2. This measurement capability is critical for facilitating a better understanding of the etiology of respiratory health effects. This article presents the development and in-plant testing of a portable, tunable diode-based HF sensor that shows equivalent or improved performance relative to NIOSH Method 7902 and is capable of measuring short-term personal peak HF exposure potentials in operating aluminum smelters.

  8. Theoretical Studies on the Stabilities and Hydrogen Bond Actions of (H2O)n Clusters

    Institute of Scientific and Technical Information of China (English)

    MENG Xiang-Jun; WANG Ke-Cheng; WU Wen-Sheng; LI Bing-Huan; WANG De-Jin


    The stable configurations and hydrogen bond nature of (H2O)n clusters (n = 3~6) have been investigated by the B3LYP method at the 6-31++g** level. Upon calculation, four conclusions have been drawn: (1) In the (H2O)3~5 clusters, cyclic configurations were confirmed to be the most stable. But in the (H2O)3~4 ones, only cyclic configurations could be observed. From n= 5 ((H2O)5 clusters), three-dimensional configuration could be found; (2) In the (H2O)6 clusters, all configurations are inclined to be three-dimensional except the most stable configuration which is cyclic; (3) The stable order of (H2O)6 clusters indicates that it is the arrangement of hydrogen bond that plays a decisive role in the cluster stabilities, the zero-point energy is also important, and cluster stabilities are independent on the number of hydrogen bonds; (4) There exist strong cooperativity and superadditivity in the (H2O)n clusters.

  9. Self-organization of hydrogen gas bubbles rising above laser-etched metallic aluminum in a weakly basic aqueous solution. (United States)

    Barmina, E V; Kuzmin, P G; Shafeev, G A


    Self-organization of hydrogen bubbles is reported under etching of metallic Aluminum in a weakly basic solution. The ascending gas bubbles drift to the areas with higher density of bubbles. As a result, ascending bubbles form various stationary structures whose symmetry is determined by the symmetry of the etched area. Bubbles are aligned along the bisectors of the contour of the etched area. The special laser-assisted profiling of the etched area in shape of a vortex induces a torque in the fluid above the etched area. The process is interpreted on the basis of Bernoulli equation.

  10. [Ca(BH4)2] n clusters as hydrogen storage material: A DFT study (United States)

    Han, Cuiling; Dong, Yanyun; Wang, Bingqiang; Zhang, Caiyun


    Calcium borohydride is widely studied as a hydrogen storage material. However, investigations on calcium borohydride from a cluster perspective are seldom found. The geometric structures and binding energies of [Ca(BH4)2] n ( n = 1-4) clusters are determined using density function theory (DFT). For the most stable structures, vibration frequency, natural bond orbital (NBO) are calculated and discussed. The charge transfer from (BH4) to Ca was observed. Meanwhile, we also study the LUMO-HOMO gap ( E g) and the B-H bond dissociation energies (BDEs). [Ca(BH4)2]3 owns higher E g, revealing that trimer is more stable than the other forms. Structures don't change during optimization after hydrogen radical removal, showing that calcium borohydride could possibly be used as a reversible hydrogen storage material. [Ca(BH4)2]4 has the smallest dissociation energy suggesting it releases hydrogen more easily than others.

  11. Application of genetic algorithms to hydrogenated silicon clusters

    Indian Academy of Sciences (India)

    N Chakraborti; R Prasad


    We discuss the application of biologically inspired genetic algorithms to determine the ground state structures of a number of Si–H clusters. The total energy of a given configuration of a cluster has been obtained by using a non-orthogonal tight-binding model and the energy minimization has been carried out by using genetic algorithms and their recent variant differential evolution. Our results for ground state structures and cohesive energies for Si–H clusters are in good agreement with the earlier work conducted using the simulated annealing technique. We find that the results obtained by genetic algorithms turn out to be comparable and often better than the results obtained by the simulated annealing technique.

  12. Innovative regions and industrial clusters in hydrogen and fuel cell technology

    DEFF Research Database (Denmark)

    Madsen, Anne Nygaard; Andersen, Per Dannemand


    will analyse regions that are highly engaged in H2FC activity, based on three indicators: existing hydrogen infrastructure and production sites, general innovativeness and the presence of industrial clusters with relevance for H2FC. Our finding is that regions with high activity in H2FC development are also...... innovative regions in general. Moreover, the article highlights some industrial clusters that create favourable conditions for regions to take part in H2FC development. Existing hydrogen infrastructure, however, seems to play only a minor role in a region’s engagement. The article concludes that, while...

  13. Trapping of hydrogen atoms inside small beryllium clusters and their ions (United States)

    Naumkin, F. Y.; Wales, D. J.


    Structure, stability and electronic properties are evaluated computationally for small Ben (n = 5-9) cluster cages accommodating atomic H inside and forming core-shell species. These parameters are predicted to vary significantly upon insertion of H, for ionic derivatives, and with the system size. In particular, the energy barrier for H-atom exit from the cage changes significantly for ions compared to the neutral counterparts. The corresponding effects predicted for cage assemblies suggest the possibility of efficient charge-control of hydrogen release. This, together with a high capacity for storing hydrogen in extended such assemblies might indicate a possible way towards feasible hydrogen-storage solutions.

  14. Sulfur Dioxide Enhances Endogenous Hydrogen Sulfide Accumulation and Alleviates Oxidative Stress Induced by Aluminum Stress in Germinating Wheat Seeds

    Directory of Open Access Journals (Sweden)

    Dong-Bo Zhu


    Full Text Available Aluminum ions are especially toxic to plants in acidic soils. Here we present evidences that SO2 protects germinating wheat grains against aluminum stress. SO2 donor (NaHSO3/Na2SO3 pretreatment at 1.2 mM reduced the accumulation of superoxide anion, hydrogen peroxide, and malondialdehyde, enhanced the activities of guaiacol peroxidase, catalase, and ascorbate peroxidase, and decreased the activity of lipoxygenase in germinating wheat grains exposed to Al stress. We also observed higher accumulation of hydrogen sulfide (H2S in SO2-pretreated grain, suggesting the tight relation between sulfite and sulfide. Wheat grains geminated in water for 36 h were pretreated with or without 1 mM SO2 donor for 12 h prior to exposure to Al stress for 48 h and the ameliorating effects of SO2 on wheat radicles were studied. SO2 donor pretreatment reduced the content of reactive oxygen species, protected membrane integrity, and reduced Al accumulation in wheat radicles. Gene expression analysis showed that SO2 donor pretreatment decreased the expression of Al-responsive genes TaWali1, TaWali2, TaWali3, TaWali5, TaWali6, and TaALMT1 in radicles exposed to Al stress. These results suggested that SO2 could increase endogenous H2S accumulation and the antioxidant capability and decrease endogenous Al content in wheat grains to alleviate Al stress.

  15. Reaction dynamics and statistical theory for the growth of hydrogen bonding clusters

    Institute of Scientific and Technical Information of China (English)

    WANG; Haijun; BA; Xinwu(巴信武); ZHAO; Min(赵敏)


    The similarities between the formation of hydrogen bonds and polycondensation reactions are stated from the statistical viewpoint, and then taking the hydrogen bonding system of AaDd type as an example, the growing process of hydrogen bonding clusters is investigated in terms of the theory of reaction dynamics and statistical theory for polymeric reactions. The two methods lead to the same conclusions, stating that the statistical theory for polymerization is applicable to the hydrogen bonding systems. Based on this consideration, the explicit relationship between the conversions of proton-donors and proton-acceptors and the Gibbs free energy of the system under study is given. Furthermore, the sol-gel phase transition is predicted to take place in some hydrogen bonding systems, and the corresponding generalized scaling laws describing this kind of phase transition are obtained.

  16. A molecular superfluid: non-classical rotations in doped para-hydrogen clusters

    CERN Document Server

    Li, Hui; Roy, Pierre-Nicholas; McKellar, A R W; 10.1103/PhysRevLett.105.133401


    Clusters of para-hydrogen (pH2) have been predicted to exhibit superfluid behavior, but direct observation of this phenomenon has been elusive. Combining experiments and theoretical simulations, we have determined the size evolution of the superfluid response of pH2 clusters doped with carbon dioxide (CO2). Reduction of the effective inertia is observed when the dopant is surrounded by the pH2 solvent. This marks the onset of molecular superfluidity in pH2. The fractional occupation of solvation rings around CO2 correlates with enhanced superfluid response for certain cluster sizes.

  17. Nanostructuring of Aluminum Alloy Powders by Cryogenic Attrition with Hydrogen-Free Process Control Agent (United States)


    times for cleanliness . The tank was then refilled, allowing the temperature to stabilize at the operating temperature (–196 °C), after which the...Ortalan V, Li WF, Zhang Z, Vogt R, Browning ND, Lavernia EJ, Schoenung JM. HRTEM and EELS study of aluminum nitride in nanostructured Al 5083/B4C

  18. Influence of aluminum location on hydrogen sorption kinetics of magnesium-based materials (United States)

    Zhou, Shixue; Zhang, Tonghuan; Wang, Naifei; Li, Tao; Niu, Haili; Yu, Hao; Liu, Di


    Hydrogen storage materials from Mg-Al alloy and Mg+Al mixture were prepared by reactive milling under H2 atmosphere with carbonized anthracite as milling aid. The crystal structure of the materials and influence of Al location on hydrogen absorption/desorption kinetics were investigated. Results show that Mg partly got hydrided into β-MgH2 and γ-MgH2 during reactive milling. The average crystallite sizes of β-MgH2 in the as-milled Mg-Al alloy and Mg+Al mixture were calculated by Scherrer equation to be 10 nm and 17 nm, respectively. In the process of hydrogen desorption, the catalytic ability of Al in Mg crystal lattice was not as effective as that on particle surface. The apparent activation energies for hydrogen desorption of the two materials were estimated by Kissinger equation to be 112.2 kJ/mol and 63.7 kJ/mol, respectively. Mg17Al12 reacted with H2 to convert into MgH2 and elemental Al during static hydrogenation at 300°C. For the hydrogenated Mg+Al mixture, the obvious increase of crystallite size resulted in a low rate of hydrogen absorption and a high temperature for hydrogen desorption.

  19. Cluster-based composition rule for Laves phase-related BCC solid solution hydrogen storage alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Qing; CHEN Feng; WU Jiang; QIANG Jianbing; DONG Chuang; ZHANG Yao; XU Fen; SUN Lixian


    A new cluster line approach for the composition rule of Laves phase-related BCC solid solution hydrogen-storage alloys was presented. The cluster line in a ternary phase diagram refers to a straight composition line linking a specific binary cluster to the third element. In the Laves phase-related BCC solid solution alloy system such as Ti-Cr-V, Ti-Cr tends to form binary Cr2Ti Laves phase while Ti-V and Cr-V to form solid solutions. This Laves phase is characterized by a close-packing icosahedral cluster Cr7Ti6. A cluster line Cr7Ti6-V is then constructed in this system. Alloy rods with a diameter of 3 mm of compositions along this line were prepared by copper-mould suction method. The alloy structure is found to vary with the V contents. Furthermore, the P-C-T measurements indicate that the cluster-line (Cr7Ti6)1-xVx alloys have large hydrogen storage capacities.

  20. Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

    DEFF Research Database (Denmark)

    Madsen, Steen; Bozhevolnyi, Sergey I.; Birkelund, Karen;


    Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium ...

  1. Dynamics of two interacting hydrogen bubbles in liquid aluminum under the influence of a strong acoustic field (United States)

    Lebon, Gerard S. B.; Pericleous, Koulis; Tzanakis, Iakovos; Eskin, Dmitry G.


    Ultrasonic melt processing significantly improves the properties of metallic materials. However, this promising technology has not been successfully transferred to the industry because of difficulties in treating large volumes of melt. To circumvent these difficulties, a fundamental understanding of the efficiency of ultrasonic treatment of liquid metals is required. In this endeavor, the dynamics of two interacting hydrogen bubbles in liquid aluminum are studied to determine the effect of a strong acoustic field on their behavior. It is shown that coalescence readily occurs at low frequencies in the range of 16 to 20 kHz; forcing frequencies at these values are likely to promote degassing. Emitted acoustic pressures from relatively isolated bubbles that resonate with the driving frequency are in the megapascal range and these cavitation shock waves are presumed to promote grain refinement by disrupting the growth of the solidification front.

  2. Aluminum Cluster-Based Materials for Propulsion and Other Applications and Catalysis (United States)


    can break polar/covalent bonds, and have made headways towards synthesis of cluster nanoassemblies and their characterization. We demonstrated that... nanoassemblies and their growth mechanisms. The studies focused on photoelectron spectra of carbon-rich triniobium carbide clusters Nb3Cn- (n = 5-10

  3. Pressure-induced hydrogen-dominant metallic state in aluminum hydride. (United States)

    Goncharenko, Igor; Eremets, M I; Hanfland, M; Tse, J S; Amboage, M; Yao, Y; Trojan, I A


    Two structural transitions in covalent aluminum hydride AlH3 were characterized at high pressure. A metallic phase stable above 100 GPa is found to have a remarkably simple cubic structure with shortest first-neighbor H-H distances ever measured except in H2 molecule. Although the high-pressure phase is predicted to be superconductive, this was not observed experimentally down to 4 K over the pressure range 120-164 GPa. The results indicate that the superconducting behavior may be more complex than anticipated.

  4. Hydrogen-rich water alleviates aluminum-induced inhibition of root elongation in alfalfa via decreasing nitric oxide production. (United States)

    Chen, Meng; Cui, Weiti; Zhu, Kaikai; Xie, Yanjie; Zhang, Chunhua; Shen, Wenbiao


    One of the earliest and distinct symptoms of aluminum (Al) toxicity is the inhibition of root elongation. Although hydrogen gas (H2) is recently described as an important bio-regulator in plants, whether and how H2 regulates Al-induced inhibition of root elongation is largely unknown. To address these gaps, hydrogen-rich water (HRW) was used to investigate a physiological role of H2 and its possible molecular mechanism. Individual or simultaneous (in particular) exposure of alfalfa seedlings to Al, or a fresh but not old nitric oxide (NO)-releasing compound sodium nitroprusside (SNP), not only increased NO production, but also led to a significant inhibition of root elongation. Above responses were differentially alleviated by pretreatment with 50% saturation of HRW. The addition of HRW also alleviated the appearance of Al toxicity symptoms, including the improvement of seedling growth and less accumulation of Al. Subsequent results revealed that the removal of NO by the NO scavenger, similar to HRW, could decrease NO production and alleviate Al- or SNP-induced inhibition of root growth. Thus, we proposed that HRW alleviated Al-induced inhibition of alfalfa root elongation by decreasing NO production. Such findings may be applicable to enhance crop yield and improve stress tolerance.

  5. The Role of Molecule Clustering by Hydrogen Bond in Hydrous Ethanol on Laminar Burning Velocity

    Directory of Open Access Journals (Sweden)

    I Made Suarta


    Full Text Available The role of hydrogen bond molecule clustering in laminar burning velocities was observed. The water in hydrous ethanol can change the interaction between water-ethanol molecules. A certain amount of water can become oxygenated which increases the burning velocity. The hydrogen bond interaction pattern of ethanol and water molecules was modeled. Based on the molecular model, azeotropic behavior emerges from ethanol-water hydrogen bond, which is at a 95.1%v composition. The interaction with water molecule causes the ethanol molecule to be clustered with centered oxygenated compound. So, it supplies extra oxygen and provides intermolecular empty spaces that are easily infiltrated by the air. In the azeotropic composition, the molecular bond chain is the shortest, so hypothetically the burning velocity is anticipated to increase. The laminar burning velocity of ethanol fuel was tested in a cylindrical explosion bomb in lean, stoichiometric, and rich mixtures. The experimental result showed that the maximum burning velocity occurred at hydrous ethanol of 95.5%v composition. This discrepancy is the result of the addition of energy from 7.7% free ethanol molecules that are not clustered. At the rich mixture, the burning velocity of this composition is higher than that of anhydrous ethanol.

  6. CO2 Activation and Hydrogenation by PtHn (-) Cluster Anions. (United States)

    Zhang, Xinxing; Liu, Gaoxiang; Meiwes-Broer, Karl-Heinz; Ganteför, Gerd; Bowen, Kit


    Gas phase reactions between PtHn (-) cluster anions and CO2 were investigated by mass spectrometry, anion photoelectron spectroscopy, and computations. Two major products, PtCO2 H(-) and PtCO2 H3 (-) , were observed. The atomic connectivity in PtCO2 H(-) can be depicted as HPtCO2 (-) , where the platinum atom is bonded to a bent CO2 moiety on one side and a hydrogen atom on the other. The atomic connectivity of PtCO2 H3 (-) can be described as H2 Pt(HCO2 )(-) , where the platinum atom is bound to a formate moiety on one side and two hydrogen atoms on the other. Computational studies of the reaction pathway revealed that the hydrogenation of CO2 by PtH3 (-) is highly energetically favorable.

  7. Evolution in the structural and bonding properties of Aluminum-Lithium clusters

    CERN Document Server

    Chacko, S; Paranjape, V V


    We present a systematic study of the geometry, energetics, electronic structure and bonding in various Al-Li clusters viz. Al_nLi_n (n=1-11), Al_2^-, Al_2^{2-}, Al_2Li, Al_2Li^-, and Al_6Li_8 using Born-Oppenheimer molecular dynamics method within the framework of density functional theory. The growth patterns in these cluster are found to be divided in two broad categories: the first consisting of a quinted roof of Al_2Li_2 (n=2-4) and the second consisting of a pentagonal ring (n=7-9). A covalent bonding between Al-Li in Al_2Li_2 is seen, whereas, in larger clusters, it is ionic. A three dimensional growth of the Al cluster in Al_4^{2-}, Al_5Li_5, and Al_6Li_8 leads to a transition from localized to delocalized bonding. In clusters with more than six Al atoms, the eigenvalue spectrum is divided into two groups: a lower group of jellium-like states and a higher group of localized bonds arising out of p complex. Thus, a mixture of localized, delocalized, and ionic bonding is seen in these clusters. Finally, w...

  8. A density functional study on the adsorption of hydrogen molecule onto small copper clusters

    Indian Academy of Sciences (India)

    Xiang-Jun Kuang; Xin-Qiang Wang; Gao-Bin Liu


    An all-electron scalar relativistic calculation on the adsorption of hydrogen molecule onto small copper clusters has been performed by using density functional theory with the generalized gradient approximation (GGA) at PW91 level. Our results reveal that after adsorption of H2 molecule, the Cu-Cu interaction is strengthened and the H-H interaction is weakened, the reactivity enhancement of H2 molecule is obvious. The VIPs, HLGs and VEAs of CuH2 clusters show an obvious odd-even oscillation. It is suggested that the H2 molecule is more favourable to be adsorbed by the even-numbered small copper clusters. Meanwhile, the odd-even alteration of magnetic moments is also observed and may be served as the material with tunable code capacity of `0’ and `1' by adsorbing hydrogen molecule onto odd or even-numbered small copper clusters. Some discrepancies of dissociative adsorption between our work and previous works are found and may be understood in terms of the electron pairing effect and the scalar relativistic effect.

  9. The hydrogen storage properties of Na decorated small boron cluster B6Na8 (United States)

    Tang, Chunmei; Wang, Zhiguo; Zhang, Xue; Wen, Ninghua


    The binding energy of the Na atoms to the hollow sites of the B6 cage is larger than the experimental cohesive energy of bulk Na, so the clustering of Na atoms can be avoided. The polarization interaction dominates the adsorption of H2 by the B6Na8 cluster. The Na-coated B6Na8sbnd B8sbnd B6Na8 complex with the dispersive Na atoms and four H2 molecules adsorbed per Na can serve as better building blocks of polymers than the (B6Na8)2 dimer. These findings suggest a new route to design cluster-assembled hydrogen storage materials based on sp2-terminated boron chains.

  10. Construction and test of a high power injector of hydrogen cluster ions

    CERN Document Server

    Becker, E W; Hagena, O F; Henkes, P R W; Klingelhofer, R; Moser, H O; Obert, W; Poth, I


    A high power injector of hydrogen cluster ions, rated for 1 MV and 100 kW, is described. The injector is split in three separate tanks connected by a 1 MV transfer line. The cluster ion beam source and all its auxiliary equipment is placed at high voltage, insulated by SF/sub 6/ gas at pressure of 4 bar. The main components of the injector are: The cluster ion beam source with integrated helium cryopumps, the CERN type acceleration tube with 750 mm ID, the beam dump designed to handle the mass and energy flux under DC conditions, a 1 MV high voltage terminal for the auxiliary equipment supplied by its 40 kVA power supply with power, and the 1 MV 120 kW DC high voltage generator. This injector is installed in Karlsruhe. Performance tests were carried out successfully. It is intended to use this injector for refuelling experiments at the ASDEX Tokamak. (12 refs).

  11. Removal of hydrogen chloride from gaseous streams using magnesium-aluminum oxide. (United States)

    Kameda, Tomohito; Uchiyama, Naoya; Park, Kye-Sung; Grause, Guido; Yoshioka, Toshiaki


    Magnesium-aluminum oxide (Mg-Al oxide) obtained by thermal decomposition of Mg-Al layered double hydroxide (Mg-Al LDH) effectively removed HCl from gaseous streams. HCl removal was greater in the presence of added water vapor at all temperatures examined and increased with decreasing temperature in both the presence and absence of added water vapor. Wet and dry removal of gaseous HCl were attributed to the production of MgCl2 . 6H2O and MgCl2 . 4H2O, respectively. For the wet scrubbing process, the reconstruction reaction of Mg-Al LDH from Mg-Al oxide was the primary mechanism for increased HCl removal.

  12. Hydrogen Content and Porosity Behavior of Hypereutectic Aluminum-silicon Alloy with Phosphorus

    Institute of Scientific and Technical Information of China (English)

    HU Li-na; BIAN Xiu-fang; DUAN You-feng


    By making castings that pick up gas from moisture in red sand molds,the porosity generated at different cooling rates was discussed during solidification of hypereutectic Al-25%Si alloy without and with phosphorus additions. The effect of phosphorus addition on hydrogen content in the melt was also studied. It was observed that the phosphorus addition made hydrogen content in alloy melts present a "see-saw" tendency.In addition to primary silicon refinement,the phosphorus promoted gas porosity formed not only in slowly cooled sections, but also in rapidly cooled sections. There was a small difference in density of full dense sample between P-refined and unrefined castings, with a larger density associated with phosphorous addition. The change of the surface tension seemed more reasonable to explain the mechanism of porosity behavior.

  13. Innovative regions and industrial clusters in hydrogen and fuel cell technology

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Anne Nygaard; Andersen, Per Dannemand [Department of Management Engineering, Technical University of Denmark, Produktionstorvet, Building 426, DK-2800 Kgs. Lyngby (Denmark)


    Regional governments in Europe seem to be playing an increasing role in hydrogen and fuel cell (H2FC) development. A number of regions are supporting demonstration projects and building networks among regional stakeholders to strengthen their engagement in H2FC technology. In this article, we will analyse regions that are highly engaged in H2FC activity, based on three indicators: existing hydrogen infrastructure and production sites, general innovativeness and the presence of industrial clusters with relevance for H2FC. Our finding is that regions with high activity in H2FC development are also innovative regions in general. Moreover, the article highlights some industrial clusters that create favourable conditions for regions to take part in H2FC development. Existing hydrogen infrastructure, however, seems to play only a minor role in a region's engagement. The article concludes that, while further research is needed before qualified policy implications can be drawn, an overall well-functioning regional innovation system is important in the formative phase of an H2FC innovation system. (author)

  14. Advance of hydrogen production from aluminum water reaction%铝水反应制氢技术研发进展

    Institute of Scientific and Technical Information of China (English)

    刘光明; 解东来


    Aluminum is the most abundant metal element in earth crust with low price and density and wide source. The reaction of aluminum with water can generate hydrogen, thus to be an effective method of hydrogen storage. Its hydrogen storage factor is up to 11.1% which is higher than 9%, the value set by U.S. Department of Energy for hydrogen storage. Therefore, aluminum is a rather preferred hydrogen carrier, as well as an ideal hydrogen storage media for proton exchange membrane fuel cell. By-products of the reaction are environmental friendly and can be recycled. Hence it attracts many researchers' attention. The recent research and development progresses in hydrogen production from the reaction of aluminum with water were reviewed. The methods to enhance the reaction process were introduced. Some of the hydrogen generators and systems invented by researchers were presented.The directions for further development were discussed.%铝是地壳中含f最多的金属元素,来谏广泛,价格低廉,密度低.铝与水反应制氢,可作为一种氢气存储的有效手段.储氢值商达11.1%(质量分数),是一种非常良好的氢载体.也是为质子交换膜燃料电池供氢的理想储氢介质,反应氢产物环境友好,副产物可以回收利用.介绍了国内外有关铝水反应制氢技术在质子交换膜燃料电池中的应用进展,讨论了几种促进反应持续进行、缩短诱导时间的方法,比较了几种制氢反应器,总结了其未来的发展趋势.

  15. Electronic Origins of the Variable Efficiency of Room-Temperature Methane Activation by Homo- and Heteronuclear Cluster Oxide Cations [XYO2](+) (X, Y = Al, Si, Mg): Competition between Proton-Coupled Electron Transfer and Hydrogen-Atom Transfer. (United States)

    Li, Jilai; Zhou, Shaodong; Zhang, Jun; Schlangen, Maria; Weiske, Thomas; Usharani, Dandamudi; Shaik, Sason; Schwarz, Helmut


    The reactivity of the homo- and heteronuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) toward methane was studied using Fourier transform ion cyclotron resonance mass spectrometry, in conjunction with high-level quantum mechanical calculations. The most reactive cluster by both experiment and theory is [Al2O2](•+). In its favorable pathway, this cluster abstracts a hydrogen atom by means of proton-coupled electron transfer (PCET) instead of following the conventional hydrogen-atom transfer (HAT) route. This mechanistic choice originates in the strong Lewis acidity of the aluminum site of [Al2O2](•+), which cleaves the C-H bond heterolytically to form an Al-CH3 entity, while the proton is transferred to the bridging oxygen atom of the cluster ion. In addition, a comparison of the reactivity of heteronuclear and homonuclear oxide clusters [XYO2](+) (X, Y = Al, Si, Mg) reveals a striking doping effect by aluminum. Thus, the vacant s-p hybrid orbital on Al acts as an acceptor of the electron pair from methyl anion (CH3(-)) and is therefore eminently important for bringing about thermal methane activation by PCET. For the Al-doped cluster ions, the spin density at an oxygen atom, which is crucial for the HAT mechanism, acts here as a spectator during the course of the PCET mediated C-H bond cleavage. A diagnostic plot of the deformation energy vis-à-vis the barrier shows the different HAT/PCET reactivity map for the entire series. This is a strong connection to the recently discussed mechanism of oxidative coupling of methane on magnesium oxide surfaces proceeding through Grignard-type intermediates.

  16. Neutral hydrogen in galaxy clusters: impact of AGN feedback and implications for intensity mapping

    CERN Document Server

    Villaescusa-Navarro, Francisco; Borgani, Stefano; Viel, Matteo; Rasia, Elena; Murante, Giuseppe; Dolag, Klaus; Steinborn, Lisa K; Biffi, Veronica; Beck, Alexander M; Ragone-Figueroa, Cinthia


    By means of zoom-in hydrodynamic simulations we quantify the amount of neutral hydrogen (HI) hosted by groups and clusters of galaxies. Our simulations, which are based on an improved formulation of smoothed particle hydrodynamics (SPH), include radiative cooling, star formation, metal enrichment and supernova feedback, and can be split in two different groups, depending on whether feedback from active galactic nuclei (AGN) is turned on or off. Simulations are analyzed to account for HI self-shielding and the presence of molecular hydrogen. We find that the mass in neutral hydrogen of dark matter halos monotonically increases with the halo mass and can be well described by a power-law of the form $M_{\\rm HI}(M,z)\\propto M^{3/4}$. Our results point out that AGN feedback reduces both the total halo mass and its HI mass, although it is more efficient in removing HI. We conclude that AGN feedback reduces the neutral hydrogen mass of a given halo by $\\sim50\\%$, with a weak dependence on halo mass and redshift. The...

  17. Healing behavior of preexisting hydrogen micropores in aluminum alloys during plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Toda, H., E-mail: [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Minami, K. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Koyama, K.; Ichitani, K. [Furukawa-Sky Aluminum Corp., 1351, Uwanodai, Fukaya, Saitama 366-8511 (Japan); Kobayashi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Uesugi, K.; Suzuki, Y. [Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)


    Synchrotron X-ray microtomography was used to observe the shrinkage and annihilation behaviors of hydrogen micropores in three dimensions during hot and cold plastic deformation of an Al-Mg alloy. Whether complete healing of micropores is achieved after plastic deformation was examined by exposing the material to a high temperature after plastic deformation. Although micropores generally show a pattern of shrinking and closing, closer inspection of a single specimen revealed a variety of geometrically variable behaviors. It is noteworthy that some of the micropores are reinitiated in positions identical to those before their annihilation, even after an 8-22% macroscopic strain has been further applied after annihilation. We attribute local variations such as these to significant local strain variation, which we measured in a series of tomographic volumes by tracking the microstructural features.

  18. Electron-induced hydrogen loss in uracil in a water cluster environment

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, M.; Kohanoff, J. [Atomistic Simulation Centre, Queen' s University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Fabrikant, I. I., E-mail: [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA and Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)


    Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A{sup ′}-resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons.

  19. Computational investigation of hydrogen adsorption in silicon-lithium binary clusters

    Indian Academy of Sciences (India)

    Naresh K Jena; K Srinivasu; Swapan K Ghosh


    Theoretical studies on hydrogen adsorption properties of silicon-lithium binary clusters are carried out. We have considered three different clusters viz., Si5Li−5, Si5Li6 and Si5Li$^{+}_{7}$ and for each cluster, the geometries of different possible isomers are optimized. In all the minimum energy isomers of the three clusters considered, two of the lithium atoms are found to be situated in the axial positions and the remaining lithium atoms are in the equatorial position in the Si5 plane. The lithium atoms which are in Si5 plane are bonded to the Si-Si edge through a bridged bond instead of a corner in the Si5 ring. From the calculated atomic charges, it is found that there is a charge transfer from lithium to silicon leaving a partial positive charge on the Li atoms and the axial lithium atoms are more charged as compared to the remaining lithium atoms. In the case of Si5Li6 and Si5Li$^{+}_{7}$, the Li sites can trap a total of 14 and 17 H2 molecules, respectively, with each bridge bonded Li site adsorbing three H2 molecules and each axial Li adsorbing one H2 molecule which corresponds to a gravimetric density of 13.33 wt% and 15.25 wt%, respectively.

  20. Predominance of cluster I Clostridium in hydrogen fermentation of galactose seeded with various heat-treated anaerobic sludges. (United States)

    Park, Jeong-Hoon; Lee, Sang-Hoon; Yoon, Jeong-Jun; Kim, Sang-Hyoun; Park, Hee-Deung


    To identify the key bacterial populations in hydrogen fermentation of galactose, a fermentor seeded with a heat-treated sludge was operated. After 27h of fermentation, the proportion of butyric acid increased to 69.4wt.% and the gas production yield reached 1.0molH2/molgalactose. In the pyrosequencing of 16S rDNA, an increase of the proportion of the phylum Firmicutes from 4.2% to 92% (mostly cluster I Clostridium) was observed. To verify the predominance and the ubiquity of the cluster, five fermentors seeded with different heat-treated anaerobic sludges having different feedstock compositions and digestion temperatures were investigated using qPCR analyses. The abundance of the cluster increased >100-fold during the fermentation, regardless of the inocula. Moreover, the abundance was negatively correlated with the lag time of hydrogen production and positively correlated with the hydrogen production rate, demonstrating the relevance of the cluster to hydrogen production. Taken together, the results clearly revealed the importance of cluster I Clostridium in the hydrogen fermentation of galactose.

  1. Hydrogen bonded rings, chains and lassos: the case of t-butyl alcohol clusters (United States)

    Zimmermann, D.; Häber, Th.; Schaal, H.; Suhm, M. A.

    Infrared OH stretching spectra of hydrogen bonded 2-methyl-propan-2-ol (t-butyl alcohol) clusters are investigated by ragout-jet FTIR spectroscopy. A spectral difference technique is used to discriminate approximately between neighbouring cluster sizes. Dimers, trimers and cyclic tetramers can be detected along with larger clusters, which exhibit a surprisingly structured vibrational fingerprint. Comparison is made to the spectra of related alcohols and to energetic and harmonic vibrational predictions from electronic structure calculations. The experimentally observed 32% increase in OH stretching wavenumber shift from methanol dimer to t-butyl alcohol dimer is reproduced at the HF/3-21G level (+ 33%). It is also qualitatively correct at the MP2/6-31+ G* level (+ 15%), whereas it has the wrong sign at the B3LYP/6-31+ G* level (-5%) and is negligible at the HF/6-31+ G* level, disregarding anharmonic effects. The cyclic tetramer of t-butyl alcohol is found to be particularly stable due to a favourable up-down alternation of the bulky t-butyl groups. Beyond the t-butyl alcohol tetramer, lasso structures are found to be energetically competitive with simple ring structures. A many-body decomposition shows that this is due to a reduced cooperativity in the sterically hindered pentamer ring. The resulting thermodynamic and kinetic relevance of cyclic tetramers is discussed.

  2. Theoretical realization of cluster-assembled hydrogen storage materials based on terminated carbon atomic chains. (United States)

    Liu, Chun-Sheng; An, Hui; Guo, Ling-Ju; Zeng, Zhi; Ju, Xin


    The capacity of carbon atomic chains with different terminations for hydrogen storage is studied using first-principles density functional theory calculations. Unlike the physisorption of H(2) on the H-terminated chain, we show that two Li (Na) atoms each capping one end of the odd- or even-numbered carbon chain can hold ten H(2) molecules with optimal binding energies for room temperature storage. The hybridization of the Li 2p states with the H(2)σ orbitals contributes to the H(2) adsorption. However, the binding mechanism of the H(2) molecules on Na arises only from the polarization interaction between the charged Na atom and the H(2). Interestingly, additional H(2) molecules can be bound to the carbon atoms at the chain ends due to the charge transfer between Li 2s2p (Na 3s) and C 2p states. More importantly, dimerization of these isolated metal-capped chains does not affect the hydrogen binding energy significantly. In addition, a single chain can be stabilized effectively by the C(60) fullerenes termination. With a hydrogen uptake of ∼10 wt.% on Li-coated C(60)-C(n)-C(60) (n = 5, 8), the Li(12)C(60)-C(n)-Li(12)C(60) complex, keeping the number of adsorbed H(2) molecules per Li and stabilizing the dispersion of individual Li atoms, can serve as better building blocks of polymers than the (Li(12)C(60))(2) dimer. These findings suggest a new route to design cluster-assembled hydrogen storage materials based on terminated sp carbon chains.

  3. The Assessment of Hydrogen Energy Systems for Fuel Cell Vehicles Using Principal Componenet Analysis and Cluster Analysis

    DEFF Research Database (Denmark)

    Ren, Jingzheng; Tan, Shiyu; Dong, Lichun


    Hydrogen energy which has been recognized as an alternative instead of fossil fuel has been developed rapidly in fuel cell vehicles. Different hydrogen energy systems have different performances on environmental, economic, and energy aspects. A methodology for the quantitative evaluation and anal......Hydrogen energy which has been recognized as an alternative instead of fossil fuel has been developed rapidly in fuel cell vehicles. Different hydrogen energy systems have different performances on environmental, economic, and energy aspects. A methodology for the quantitative evaluation...... to verify the correctness and accuracy of the principal components (PCs) determined by PCA in this paper. A case including 11 different hydrogen energy systems for fuel cell vehicles has been studied in this paper, and the system using steam reforming of natural gas for hydrogen production, pipeline...... for transportation of hydrogen, hydrogen gas tank for the storage of hydrogen at refueling stations, and gaseous hydrogen as power energy for fuel cell vehicles has been recognized as the best scenario. Also, the clustering results calculated by CA are consistent with those determined by PCA, denoting...

  4. Acetylene hydrogenation on anatase TiO2(101) supported Pd4 cluster: oxygen deficiency effect. (United States)

    Yang, Jie; Cao, Li-Xin; Wang, Gui-Chang


    Acetylene hydrogenation on both the perfect and oxygen defective anatase TiO(2)(101) surfaces supported Pd(4) cluster has been studied using density functional theory calculations with a Hubbard U correction (DFT + U). The adsorbed Pd(4) cluster on the perfect surface prefers to form a tetrahedral structure, while it likely moves to the oxygen defective site to form a distorted tetrahedral structure by removing a bridging oxygen atom. For the defective surface, it exhibits a stronger ability to capture Pd(4) cluster as charge transfer is significantly performed due to the oxygen deficiency. Moreover, it is found that the oxygen defective surface shows higher activity for acetylene hydrogenation, and the possible reason may lie in the weaker adsorption strength between the Pd cluster and the adsorbed molecules on the defective surface as compared to the case on the perfect surface.

  5. Study on the Kinetics of Hydrogen Evolution in Aluminum Alloy Casting%铝合金铸造过程中析氢动力学研究

    Institute of Scientific and Technical Information of China (English)

    周迪生; 龙伟; 张恒华


    There always exists the phenomenon of hydrogen absorption in aluminum alloy melt. When melt temperature dropped, the solubility of hydrogen in melt decreased and the hydrogen precipitated from melt, which resulted in the blowhole and porosity in cast ingots or workpieces. Different mould preheating temperatures and decompression solidification were used in casting, the effect of mold preheating temperature on the diffusion rate and diffusion distance of hydrogen, the solidification pressure on the critical nucleation radius and growth of hydrogen bubble were analyzed. The results show that hydrogen diffusion and precipitation was inhibited at low mold preheating temperature, high solidification pressure produced large critical nucleation radius of hydrogen bubble and restrained the nucleation and growth of gas bubble. Hydrogen was dissolved in aluminum alloy melt and the comparability of the structure was improved in low mould preheating temperature and high solidification pressure.%铝及其合金在熔炼过程中,往往存在吸氢现象.当熔体温度下降时,氢在熔体中的溶解度下降,会从熔体中析出,导致铸锭或工件产生气孔、疏松等缺陷.采用不同模具预热温度浇注和减压凝固,分析了模具预热温度对熔体中氢扩散速度及扩散距离的影响,凝固压强对氢气泡临界形核半径和长大的影响.结果表明,低的模具预热温度抑制熔体中氢的扩散和析出;凝固压力大时氢气泡的临界形核半径较大,抑制气泡的形核和长大.所以低的模具预热温度和高的凝固压强可使氢固溶在铝合金中,从而提高其组织的致密性.

  6. A Warm Molecular Hydrogen Tail Due to Ram Pressure Stripping of a Cluster Galaxy

    CERN Document Server

    Sivanandam, Suresh; Rieke, George H


    We have discovered a remarkable warm (140 - 160 K) molecular hydrogen tail with a mass of approximately 2.5*10^7 M_sun extending 20 kpc from a cluster spiral galaxy, ESO 137-001, in Abell 3627. Some portion of this gas is lost permanently to the intracluster medium, as the tail extends beyond the tidal radius of the galaxy. We also detect a hot (580 - 680 K) component in the tail that is approximately 1% of the mass of the warm component. This discovery is direct evidence that the galaxy is currently undergoing ram-pressure stripping, as also indicated by its X-ray and H\\alpha tail found by other studies. We estimate the galaxy is losing its interstellar gas at a rate of at least ~ 1 - 2 M_sun yr^-1. If the galaxy persists to lose mass at this estimated rate, it will exhaust its gas reservoir in a single pass through the cluster core, which will take approximately 0.5 - 1 Gyr. The results produced from the modeling of the ram-pressure stripping timescale are consistent with our upper limit and suggest that th...

  7. Understanding the Vancouver hydrogen and fuel cells cluster : a case study of public laboratories and private research

    Energy Technology Data Exchange (ETDEWEB)

    Holbrook, A. [Simon Fraser Univ., Burnaby, BC (Canada). Centre for Policy Research on Science and Technology; Arthurs, D. [Hickling Arthurs Low Corp., Ottawa, ON (Canada); Cassidy, E. [National Research Council of Canada, Ottawa, ON (Canada)


    A technology cluster is a geographically proximate group of interconnected companies and associated institutions that compete but also cooperate. Studies have shown that firms who cluster achieve greater competitive advantages over those who do not. This paper discussed the development of a hydrogen and fuel cells cluster in the city of Vancouver. A structured approach was used to evaluate the cluster against indicators of current conditions in the city. The results of a survey conducted with industry representatives and business leaders suggested that the cluster will contain 2 major components: (1) a hydrogen-based industry; and (2) a fuel cell-based industry. Developments in both technologies were discussed in relation to stationary and mobile applications in the future. Markets for the new technologies were also outlined. The role of the National Research Council (NRC) in the cluster's evolution was discussed. Details of the cluster's business characteristics and plans for the future were also provided. 16 refs., 7 tabs., 7 figs.

  8. Hydrogen bonded networks in formamide [HCONH2] ( = 1 − 10) clusters: A computational exploration of preferred aggregation patterns

    Indian Academy of Sciences (India)

    A Subha Mahadevi; Y Indra Neela; G Narahari Sastry


    Application of quantum chemical calculations is vital in understanding hydrogen bonding observed in formamide clusters, a prototype model for motifs found in protein secondary structure. DFT calculations have been performed on four arrangements of formamide clusters [HCONH2], ( = 1 − 10) linear, circular, helical and stacked forms. These studies reveal the maximum cooperativity in the stacked arrangement followed by the circular, helical and linear arrangements and is based on interaction energy per monomer. In all these arrangements as we increase cluster size, an increasing trend in cooperativity of hydrogen bonding is observed. Atoms-in-molecule analysis establishes the nature of bonding between the formamide monomers on the basis of electron density values obtained at the bond critical point (BCP).

  9. 铝电解中二氧化锡基(氢气)气体阳极%SnO2-based gas (hydrogen) anodes for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)



    开发一种在低温电解质(850°C)铝电解中应用的新型二氧化锡基气体阳极以降低铝电解能耗和二氧化碳排放。在此种气体阳极中,氢气通入阳极后参与阳极反应,分别用石墨和铝作阴极和参比电极。采用循环伏安法研究此体系中铂和二氧化锡基电极上氧离子的电化学行为,并确定氧气的析出电势。然后,采用气体电极进行恒电流电解实验,相对于未通入气体和通入氩气,通入氢气后阳极出现明显的去极化现象(阳极电势约下降0.8 V)。实验结果表明,氢气已参与阳极三相界面(气体−电解质−电极)反应,为还原性气体阳极在铝电解上的应用提供了可行性。%A novel SnO2-based gas anode was developed for aluminum electrolysis in molten cryolite at 850 °C to reduce energy consumption and decrease CO2 emissions. Hydrogen was introduced into the anode, participating in the anode reaction. Carbon and aluminum were used as the cathode and reference electrodes, respectively. Cyclic voltammetry was applied in the cell to investigate the electrochemical behavior of oxygen ion on platinum and SnO2-based materials. The potential for oxygen evolution on these electrode materials was determined. Then, galvanostatic electrolysis was performed on the gas anode, showing a significant depolarization effect (a decrease of ~0.8 V of the anode potential) after the introduction of hydrogen, compared with no gas introduction or the introduction of argon. The results indicate the involvement of hydrogen in the anode reaction (three-phase-boundary reaction including gas, electrolyte and electrode) and give the possibility for the utilization of reducing gas anodes for aluminum electrolysis.

  10. Study of the interplay between N-graphene defects and small Pd clusters for enhanced hydrogen storage via a spill-over mechanism. (United States)

    Rangel, E; Sansores, E; Vallejo, E; Hernández-Hernández, A; López-Pérez, P A


    The hydrogen spill-over mechanism was studied by applying Density Functional Theory. We used small palladium clusters to act as the catalyst supported on the substrate (comprised of pyridinic and pyrrolic nitrogen doped graphene), in order to study hydrogen dissociation, migration and diffusion. Charge transfer and strong binding between the catalyst and the substrate lead to dissociated states of H2 and prevent clusters from detaching and coalescing. In dissociated cases of H2 on Pd clusters, energy barriers below 0.6 eV were found. Likewise, concerning hydrogen migration from the catalyst to the substrate, energy barrier values of 0.8 eV (pyridinic defect) and 0.5 eV (pyrrolic defect) were apparent in the case of the Pd4 cluster at full hydrogen saturation. This indicates that hydrogen dissociation and migration may occur spontaneously at room temperature. This result shows that the interaction between the defects and the small metal clusters may explain the role that defects play in hydrogen migration from the catalyst to the substrate. Subsequently, it was found that thermal desorption does not limit chemisorbed hydrogen diffusion on the substrate. This work may thus help to determine experimental strategies with the capacity to enhance hydrogen storage.

  11. Coupled cluster and density functional theory calculations of atomic hydrogen chemisorption on pyrene and coronene as model systems for graphene hydrogenation. (United States)

    Wang, Ying; Qian, Hu-Jun; Morokuma, Keiji; Irle, Stephan


    Ab initio coupled cluster and density functional theory studies of atomic hydrogen addition to the central region of pyrene and coronene as molecular models for graphene hydrogenation were performed. Fully relaxed potential energy curves (PECs) were computed at the spin-unrestricted B3LYP/cc-pVDZ level of theory for the atomic hydrogen attack of a center carbon atom (site A), the midpoint of a neighboring carbon bond (site B), and the center of a central hexagon (site C). Using the B3LYP/cc-pVDZ PEC geometries, we evaluated energies at the PBE density functional, as well as ab initio restricted open-shell ROMP2, ROCCSD, and ROCCSD(T) levels of theory, employing cc-pVDZ and cc-pVTZ basis sets, and performed a G2MS extrapolation to the ROCCSD(T)/cc-pVTZ level of theory. In agreement with earlier studies, we find that only site A attack leads to chemisorption. The G2MS entrance channel barrier heights, binding energies, and PEC profiles are found to agree well with a recent ab initio multireference wave function theory study (Bonfanti et al. J. Chem. Phys.2011, 135, 164701), indicating that single-reference open-shell methods including B3LYP are sufficient for the theoretical treatment of the interaction of graphene with a single hydrogen atom.

  12. Adsorption and chemical reaction of gaseous mixtures of hydrogen chloride and water on aluminum oxide and application to solid-propellant rocket exhaust clouds (United States)

    Cofer, W. R., III; Pellett, G. L.


    Hydrogen chloride (HCl) and aluminum oxide (Al2O3) are major exhaust products of solid rocket motors (SRM). Samples of calcination-produced alumina were exposed to continuously flowing mixtures of gaseous HCl/H2O in nitrogen. Transient sorption rates, as well as maximum sorptive capacities, were found to be largely controlled by specific surface area for samples of alpha, theta, and gamma alumina. Sorption rates for small samples were characterized linearly with an empirical relationship that accounted for specific area and logarithmic time. Chemisorption occurred on all aluminas studied and appeared to form from the sorption of about a 2/5 HCl-to-H2O mole ratio. The chemisorbed phase was predominantly water soluble, yielding chloride/aluminum III ion mole ratios of about 3.3/1 suggestive of dissolved surface chlorides and/or oxychlorides. Isopiestic experiments in hydrochloric acid indicated that dissolution of alumina led to an increase in water-vapor pressure. Dissolution in aqueous SRM acid aerosol droplets, therefore, might be expected to promote evaporation.

  13. The effect of zinc on the aluminum anode of the aluminum-air battery (United States)

    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.

  14. Mechanistic Insights on C-O and C-C Bond Activation and Hydrogen Insertion during Acetic Acid Hydrogenation Catalyzed by Ruthenium Clusters in Aqueous Medium

    Energy Technology Data Exchange (ETDEWEB)

    Shangguan, Junnan; Olarte, Mariefel V.; Chin, Ya-Huei [Cathy


    Catalytic pathways for acetic acid (CH3COOH) and hydrogen (H2) reactions on dispersed Ru clusters in the aqueous medium and the associated kinetic requirements for C-O and C-C bond cleavages and hydrogen insertion are established from rate and isotopic assessments. CH3COOH reacts with H2 in steps that either retain its carbon backbone and lead to ethanol, ethyl acetate, and ethane (47-95 %, 1-23 %, and 2-17 % carbon selectivities, respectively) or break its C-C bond and form methane (1-43 % carbon selectivities) at moderate temperatures (413-523 K) and H2 pressures (10-60 bar, 298 K). Initial CH3COOH activation is the kinetically relevant step, during which CH3C(O)-OH bond cleaves on a metal site pair at Ru cluster surfaces nearly saturated with adsorbed hydroxyl (OH*) and acetate (CH3COO*) intermediates, forming an adsorbed acetyl (CH3CO*) and hydroxyl (OH*) species. Acetic acid turnover rates increase proportionally with both H2 (10-60 bar) and CH3COOH concentrations at low CH3COOH concentrations (<0.83 M), but decrease from first to zero order as the CH3COOH concentration and the CH3COO* coverages increase and the vacant Ru sites concomitantly decrease. Beyond the initial CH3C(O)-OH bond activation, sequential H-insertions on the surface acetyl species (CH3CO*) lead to C2 products and their derivative (ethanol, ethane, and ethyl acetate) and the competitive C-C bond cleavage of CH3CO* causes the eventual methane formation. The instantaneous carbon selectivities towards C2 species (ethanol, ethane, and ethyl acetate) increase linearly with the concentration of proton-type Hδ+ (derived from carboxylic acid dissociation) and chemisorbed H*. The selectivities towards C2 products decrease with increasing temperature, because of higher observed barriers for C-C bond cleavage than H-insertion. This study offers an interpretation of mechanism and energetics and provides kinetic evidence of carboxylic acid assisted proton-type hydrogen (Hδ+) shuffling during H

  15. Fabrication of Pd Micro-Membrane Supported on Nano-Porous Anodized Aluminum Oxide for Hydrogen Separation. (United States)

    Kim, Taegyu


    In the present study, nano-porous anodized aluminum oxide (AAO) was used as a support of the Pd membrane. The AAO fabrication process consists of an electrochemical polishing, first/second anodizing, barrier layer dissolving and pores widening. The Pd membrane was deposited on the AAO support using an electroless plating with ethylenediaminetetraacetic acid (EDTA) as a plating agent. The AAO had the regular pore structure with the maximum pore diameter of ~100 nm so it had a large opening area but a small free standing area. The 2 µm-thick Pd layer was obtained by the electroless plating for 3 hours. The Pd layer thickness increased with increasing the plating time. However, the thickness was limited to ~5 µm in maximum. The H2 permeation flux was 0.454 mol/m2-s when the pressure difference of 66.36 kPa0.5 was applied at the Pd membrane under 400 °C.


    Institute of Scientific and Technical Information of China (English)

    Xiao-ping Yan; Bao-lin He; Jie Zhang; Han-fan Liu


    Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate. Compared to the enantiomeric excess (e.e.) value (71.4%)obtained without the presence of metal cations, obvious e.e. enhancement (up to 82.5%) was resulted from the addition of Zn2+ but with a certain decrease in activity. The reaction parameters in the presence of Zn2+ were also studied. It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.

  17. Hydrogen-bonded clusters of 1, 1'-ferrocenedicarboxylic acid on Au(111) are initially formed in solution. (United States)

    Quardokus, Rebecca C; Wasio, Natalie A; Brown, Ryan D; Christie, John A; Henderson, Kenneth W; Forrest, Ryan P; Lent, Craig S; Corcelli, Steven A; Kandel, S Alex


    Low-temperature scanning tunneling microscopy is used to observe self-assembled structures of ferrocenedicarboxylic acid (Fc(COOH)2) on the Au(111) surface. The surface is prepared by pulse-deposition of Fc(COOH)2 dissolved in methanol, and the solvent is evaporated before imaging. While the rows of hydrogen-bonded dimers that are common for carboxylic acid species are observed, the majority of adsorbed Fc(COOH)2 is instead found in six-molecule clusters with a well-defined and chiral geometry. The coverage and distribution of these clusters are consistent with a random sequential adsorption model, showing that solution-phase species are determinative of adsorbate distribution for this system under these reaction conditions.

  18. Nitriles as directionally tolerant hydrogen bond acceptors: IR-UV ion depletion spectroscopy of benzenepropanenitrile and its hydrate clusters (United States)

    Robertson, Patrick A.; Lobo, Isabella A.; Wilson, David J. D.; Robertson, Evan G.


    Benzenepropanenitrile (BPN) and its hydrate clusters are studied by R2PI and IR-UV ion-depletion spectroscopy in the CH/OH stretch regions, aided by theoretical calculations. A single water molecule binds to the terminal nitrile 'lone-pair' of the anti-BPN host, but there is also evidence for a side-type structure with OH donating to the nitrile π-electrons. In the gauche-BPN cluster, water is located at an intermediate angle that facilitates O⋯HC(ortho) interaction. A wide range of attachment angles is possible, as the intrinsic preference for linear hydrogen bonding is mediated by additional CH⋯O interactions that depend on molecular geometry near the nitrile group.

  19. A systematic investigation of cooperativity between two types of hydrogen bonding in the nonlinear clusters of an aromatic molecule: Pyrazole (United States)

    Amini, Saeed K.


    Crystalline pyrazole consists of nonlinear chains of an aromatic molecule. It includes two independent molecules which in turn causes two different types of hydrogen bonds (HBs). These two types of HBs with slight differences in their Nsbnd H⋯N geometries can be considered as interesting ones in the recent studies of cooperativity between different HBs. These HBs are investigated in several pyrazole clusters by electronic structure calculations. Parameters such as structure, binding energy, charge transfer, chemical shielding and electric field gradient (EFG) parameters calculated at the second order Moller-Plesset perturbation (MP2) and density functional (DF) levels of theory. Both the basis set superposition error (BSSE) and zero point vibrational energy (ZPVE) corrections on the cooperativity enhancement were considered. Changes of different properties of clusters against crystal size were investigated by proposed diagrams fitted to a logarithmic function which renders their extrema in the crystal limit. In each cluster, pyrazole molecules for which their parameters are more affected by cooperativity enhancement were explored employing these fitted diagrams. Most calculated energetic and spectroscopic parameters were in good linear correlations with both the structural parameters and charge transfer along HB (q). These correlations in the cases of nuclear magnetic resonance (NMR) and nuclear quadrupolar resonance (NQR) parameters, were explained in the terms of natural charges of bonding (σ(N1sbnd H1)) and antibonding (σ*(N1sbnd H1)) orbitals. Organizing calculated data for mental clusters with similar molecules and HB types produced better regression values in all linear correlations. According to the experimental CQ of N(2) in solid state and zero charge transfer in the gas phase, the value of charge transfer in the crystalline pyrazole and gas phase value of CQ of N(2) were assessed, respectively. Diagrams of the structural parameters against either

  20. Comparison of Hydrogen Elimination from Molecular Zinc and Magnesium Hydride Clusters

    NARCIS (Netherlands)

    Intemann, J.; Sirsch, Peter; Harder, Sjoerd


    In analogy to the previously reported tetranuclear magnesium hydride cluster with a bridged dianionic bis-beta-diketiminate ligand, a related zinc hydride cluster has been prepared. The crystal structures of these magnesium and zinc hydride complexes are similar: the metal atoms are situated at the

  1. Theoretical study of hydrogen adsorption on Ca-decorated C{sub 48}B{sub 12} clusters

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Pengtang; Chen, Hongshan, E-mail: [Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China)


    The hydrogen adsorption on Ca-decorated C{sub 48}B{sub 12} clusters is studied using density functional theory. The favorable binding site for Ca atom is the hexagonal C{sub 4}B{sub 2} rings. The strong interaction between Ca atoms and C{sub 48}B{sub 12} cluster hinders the aggregation of Ca atoms on the cluster surface. C{sub 48}B{sub 12} is an electron deficient system with a large electron affinity of 2.952 eV. The decorated Ca atoms transfer their electrons to the cluster easily. The net charges on the Ca atoms are in the range of 1.101 to 1.563 e. When H{sub 2} molecules approach the Ca atoms, they are moderately polarized and adsorbed around the Ca atoms in molecular form. The adsorption strength can reach up to 0.133 eV/H{sub 2}. Each Ca atom in the Ca-decorated C{sub 48}B{sub 12} complexes can adsorb three H{sub 2} molecules. The fully decorated C{sub 48}B{sub 12}Ca{sub 6} can hold up to 18 H{sub 2} molecules.

  2. An ALMT1 gene cluster controlling aluminium (aluminum) tolerance at the Alt4 locus of rye (Secale cereale L.) (United States)

    Aluminium toxicity is a major problem in agriculture worldwide. Among the cultivated triticeae, rye (Secale cereale L.) is one of the most Al-tolerant and represents an important potential source of Al-tolerance for improvement of wheat. The Alt4 Al-tolerance locus of rye contains a cluster of genes...

  3. Silver quantum cluster (ag9 )-grafted graphitic carbon nitride nanosheets for photocatalytic hydrogen generation and dye degradation. (United States)

    Sridharan, Kishore; Jang, Eunyong; Park, Jung Hyun; Kim, Jong-Ho; Lee, Jung-Ho; Park, Tae Joo


    We report the visible-light photocatalytic properties of a composite system consisting of silver quantum clusters [Ag9 (H2 MSA)7 ] (H2 MSA=mercaptosuccinic acid) embedded on graphitic carbon nitride nanosheets (AgQCs-GCN). The composites were prepared through a simple chemical route; their structural, chemical, morphological, and optical properties were characterized by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, transmission electron microscopy, UV/Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Embedment of [Ag9 (H2 MSA)7 ] on graphitic carbon nitride nanosheets (GCN) resulted in extended visible-light absorption through multiple single-electron transitions in Ag quantum clusters and an effective electronic structure for hydroxyl radical generation, which enabled increased activity in the photocatalytic degradation of methylene blue and methyl orange dye molecules compared with pristine GCN and silver nanoparticle-grafted GCN (AgNPs-GCN). Similarly, the amount of hydrogen generated by using AgQCs-GCN was 1.7 times higher than pristine GCN. However, the rate of hydrogen generated using AgQCs-GCN was slightly less than that of AgNPs-GCN because of surface hydroxyl radical formation. The plausible photocatalytic processes are discussed in detail.

  4. Aluminum-Scandium Alloys: Material Characterization, Friction Stir Welding, and Compatibility With Hydrogen Peroxide (MSFC Center Director's Discretionary Fund Final Report, Proj. No. 04-14) (United States)

    Lee, J. A.; Chen, P. S.


    This Technical Memorandum describes the development of several high-strength aluminum (Al) alloys that are compatible with hydrogen peroxide (H2O2) propellant for NASA Hypersonic-X (Hyper-X) vehicles fuel tanks and structures. The yield strengths for some of these Al-magnesium-based alloys are more than 3 times stronger than the conventional 5254-H112 Al alloy, while maintaining excellent H2O2 compatibility similar to class 1 5254 alloy. The alloy development strategy is to add scandium, zirconium, and other transitional metals with unique electrochemical properties, which will not act as catalysts, to decompose the highly concentrated 90 percent H2O2. Test coupons are machined from sheet metals for H2O2 long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloys using friction stir welding has also been explored. The new high-strength alloys could represent an enabling material technology for Hyper-X vehicles, where flight weight reduction is a critical requirement.

  5. Regenerable Subnanometer Pd Clusters on Zirconia for Highly Selective Hydrogenation of Biomass-Derived Succinic Acid in Water

    Directory of Open Access Journals (Sweden)

    Chi Zhang


    Full Text Available The size of metal particles is an important factor to determine the performance of the supported metal catalysts. In this work, we report subnanometer Pd clusters supported on zirconia by the microwave-assisted hydrothermal method. The presence of subnanometer Pd clusters on the zirconia surface was confirmed by two-dimensional Gaussian-function fits of the aberration-corrected high-angle annual dark-field images. These subnanometer Pd catalysts exhibit high catalytic performance for the hydrogenation of biomass-derived succinic acid to γ-butyrolactone in water and avoid the formation of overhydrogenated products, such as 1,4-butanediol and tetrahydrofuran. The catalyst with an ultra-low Pd loading of 0.2 wt. % demonstrated high selectivity (95% for γ-butyrolactone using water as a solvent at 473 K and 10 MPa. Moreover, it can be reused at least six times without the loss of catalytic activity, illustrating high performance of the small Pd clusters.

  6. Hydrogen

    Directory of Open Access Journals (Sweden)

    John O’M. Bockris


    Full Text Available The idea of a “Hydrogen Economy” is that carbon containing fuels should be replaced by hydrogen, thus eliminating air pollution and growth of CO2 in the atmosphere. However, storage of a gas, its transport and reconversion to electricity doubles the cost of H2 from the electrolyzer. Methanol made with CO2 from the atmosphere is a zero carbon fuel created from inexhaustible components from the atmosphere. Extensive work on the splitting of water by bacteria shows that if wastes are used as the origin of feed for certain bacteria, the cost for hydrogen becomes lower than any yet known. The first creation of hydrogen and electricity from light was carried out in 1976 by Ohashi et al. at Flinders University in Australia. Improvements in knowledge of the structure of the semiconductor-solution system used in a solar breakdown of water has led to the discovery of surface states which take part in giving rise to hydrogen (Khan. Photoelectrocatalysis made a ten times increase in the efficiency of the photo production of hydrogen from water. The use of two electrode cells; p and n semiconductors respectively, was first introduced by Uosaki in 1978. Most photoanodes decompose during the photoelectrolysis. To avoid this, it has been necessary to create a transparent shield between the semiconductor and its electronic properties and the solution. In this way, 8.5% at 25 °C and 9.5% at 50 °C has been reached in the photo dissociation of water (GaP and InAs by Kainthla and Barbara Zeleney in 1989. A large consortium has been funded by the US government at the California Institute of Technology under the direction of Nathan Lewis. The decomposition of water by light is the main aim of this group. Whether light will be the origin of the post fossil fuel supply of energy may be questionable, but the maximum program in this direction is likely to come from Cal. Tech.

  7. A DFT study of CO2 hydrogenation on faujasite supported Ir4 clusters: on the role of water for selectivity control



    Abstract Reaction mechanisms for the catalytic hydrogenation of CO2 by faujasite‐supported Ir4 clusters were studied by periodic DFT calculations. The reaction can proceed through two alternative paths. The thermodynamically favoured path results in the reduction of CO2 to CO, whereas the other, kinetically preferred channel involves CO2 hydrogenation to formic acid under water‐free conditions. Both paths are promoted by catalytic amounts of water confined inside the zeolite micropores with a...

  8. Benchmarking ab initio binding energies of hydrogen-bonded molecular clusters based on FTIR spectroscopy

    DEFF Research Database (Denmark)

    Bork, Nicolai Christian; Du, Lin; Reiman, Heidi;


    Models of formation and growth of atmospheric aerosols are highly dependent on accurate cluster binding energies. These are most often calculated by ab initio electronic structure methods but remain associated with significant uncertainties. We present a computational benchmarking study......) and compare this range to predictions from several widely used electronic structure methods, including five density functionals, Møller-Plesset perturbation theory, and five coupled cluster methods up to CCSDT quality, considering also the D3 dispersion correctional scheme. With some exceptions, we find...... that most electronic structure methods overestimate ΔG°295 K. The effects of vibrational anharmonicity is approximated using scaling factors, reducing ΔG°295 K by ca. 1.8 kJ mol(-1), whereby ΔG°295 K predictions well within the experimental range can be obtained....

  9. The Hydrogen-Burning Limit in the Globular Cluster NGC 6397 {GO part} (United States)

    King, Ivan


    We propose a major enhancement of an earlier study of the bottom of the main sequence of NGC 6397, the globular cluster with the smallest distance modulus. In earlier work the lowest part of the MS had been lost among the numerically dominant field stars; but accurate astrometry, over a baseline of a few years, now allows an excellent proper-motion separation of faint cluster stars from the field. The purified CMD follows the main sequence to its ``end" {i.e., the terminal plunge of the LF}. Just as the MS CMD gives a mass-radius relation, we show in a new way how this LF can give a mass-luminosity relation; both of these offer unique checks on theory. Our single WFPC2 field, however, had only a small number of stars in this range, too few to set firm restraints on the theories. We propose now to increase the number of such stars by a large factor by {1} getting 2nd-epoch images for three more fields in the cluster and {2}, in an accompanying AR proposal, remeasuring our previous images, and others that exist, to the deeper limit that we know can be attained. The number and the magnitudes of these faintest stars will greatly strengthen the constraints that we place on structure and atmosphere theories of lower-main-sequence stars. In each field we will also measure the anisotropy of internal stellar motions, which is predicted to be large in a collapsed-core cluster such as this one.

  10. The Hydrogen-Burning Limit in the Globular Cluster NGC 6397 {AR part} (United States)

    King, Ivan


    We propose a major enhancement of an earlier study of the bottom of the main sequence of NGC 6397, the globular cluster with the smallest distance modulus. In earlier work the lowest part of the MS had been lost among the numerically dominant field stars; but accurate astrometry, over a baseline of a few years, now allows an excellent proper-motion separation of faint cluster stars from the field. The purified CMD follows the main sequence to its ``end" {i.e., the terminal plunge of the LF}. Just as the MS CMD gives a mass-radius relation, we show in a new way how this LF can give a mass-luminosity relation; both of these offer unique checks on theory. Our single WFPC2 field, however, had only a small number of stars in this range, too few to set firm restraints on the theories. We propose now to increase the number of such stars by a large factor by {1} getting 2nd-epoch images for three more fields in the cluster and, {2} in an accompanying AR proposal, remeasuring our previous images, and others that exist, to the deeper limit that we know can be attained. The number and the magnitudes of these faintest stars will greatly strengthen the constraints that we place on structure and atmosphere theories of lower-main-sequence stars. In each field we will also measure the anisotropy of internal stellar motions, which is predicted to be large in a collapsed-core cluster such as this one. as this one.

  11. Path integral molecular dynamics simulation of quasi-free rotational motion of CO doped in a large para-hydrogen cluster (United States)

    Mizumoto, Yoshihiko; Ohtsuki, Yukiyoshi


    Path integral molecular dynamics simulation is used to study the rotational motion of a CO molecule doped in a large para-hydrogen (p-H2) cluster. The quasi-free rotational motion of CO in a p-H2 cluster with a reduced rotational constant is derived from the imaginary-time orientational correlation functions, and is in good agreement with recent experimental observations. We attribute the reduced rotational constant to the low-viscous fluid-like behavior of the host p-H2 cluster.

  12. Path-integral molecular dynamics simulations of hydrated hydrogen chloride cluster HCl(H{sub 2}O){sub 4} on a semiempirical potential energy surface

    Energy Technology Data Exchange (ETDEWEB)

    Takayanagi, Toshiyuki, E-mail: [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Takahashi, Kenta; Kakizaki, Akira [Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan); Shiga, Motoyuki [Center for Computational Science and E-systems, Japan Atomic Energy Agency, Higashi-Ueno 6-9-3, Taito-ku, Tokyo 110-0015 (Japan); Tachikawa, Masanori [Quantum Chemistry Division, International Graduate School of Arts and Sciences, Yokohama-City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027 (Japan)


    Path-integral molecular dynamics simulations for the HCl(H{sub 2}O){sub 4} cluster have been performed on the ground-state potential energy surface directly obtained on-the-fly from semiempirical PM3-MAIS molecular orbital calculations. It is found that the HCl(H{sub 2}O){sub 4} cluster has structural rearrangement above the temperature of 300 K showing a liquid-like behavior. Quantum mechanical fluctuation of hydrogen nuclei plays a significant role in structural arrangement processes in this cluster.

  13. Path-integral molecular dynamics simulations of hydrated hydrogen chloride cluster HCl(H 2O) 4 on a semiempirical potential energy surface (United States)

    Takayanagi, Toshiyuki; Takahashi, Kenta; Kakizaki, Akira; Shiga, Motoyuki; Tachikawa, Masanori


    Path-integral molecular dynamics simulations for the HCl(H 2O) 4 cluster have been performed on the ground-state potential energy surface directly obtained on-the-fly from semiempirical PM3-MAIS molecular orbital calculations. It is found that the HCl(H 2O) 4 cluster has structural rearrangement above the temperature of 300 K showing a liquid-like behavior. Quantum mechanical fluctuation of hydrogen nuclei plays a significant role in structural arrangement processes in this cluster.

  14. Hydrogenated uniform Pt clusters supported on porous CaMnO(3) as a bifunctional electrocatalyst for enhanced oxygen reduction and evolution. (United States)

    Han, Xiaopeng; Cheng, Fangyi; Zhang, Tianran; Yang, Jingang; Hu, Yuxiang; Chen, Jun


    Hydrogenated uniform Pt clusters supported on porous CaMnO3 nanocomposites are synthesized and investigated as a new electrocatalytic material for oxygen reduction and evolution reactions. Due to the synergistic effect of Pt and CaMnO3, the nanocomposites exhibit superior activity and durability to the benchmark Pt/C catalyst.

  15. Effect of hydrogen atoms on the structures of trinuclear metal carbonyl clusters: trinuclear manganese carbonyl hydrides. (United States)

    Liu, Xian-mei; Wang, Chao-yang; Li, Qian-shu; Xie, Yaoming; King, R Bruce; Schaefer, Henry F


    The structures of the trinuclear manganese carbonyl hydrides H(3)Mn(3)(CO)(n) (n = 12, 11, 10, 9) have been investigated by density functional theory (DFT). Optimization of H(3)Mn(3)(CO)(12) gives the experimentally known structure in which all carbonyl groups are terminal and each edge of a central Mn(3) equilateral triangle is bridged by a single hydrogen atom. This structure establishes the canonical distance 3.11 A for the Mn-Mn single bond satisfying the 18-electron rule. The central triangular (mu-H)(3)Mn(3) unit is retained in the lowest energy structure of H(3)Mn(3)(CO)(11), which may thus be derived from the H(3)Mn(3)(CO)(12) structure by removal of a carbonyl group with concurrent conversion of one of the remaining carbonyl groups into a semibridging carbonyl group to fill the resulting hole. The potential energy surface of H(3)Mn(3)(CO)(10) is relatively complicated with six singlet and five triplet structures. One of the lower energy H(3)Mn(3)(CO)(10) structures has one of the hydrogen atoms bridging the entire Mn(3) triangle and the other two hydrogen atoms bridging Mn-Mn edges. This H(3)Mn(3)(CO)(10) structure achieves the favored 18-electron configuration with a very short MnMn triple bond of 2.36 A. The other low energy H(3)Mn(3)(CO)(10) structure retains the (mu-H)(3)Mn(3) core of H(3)Mn(3)(CO)(12) but has a unique six-electron donor eta(2)-mu(3) carbonyl group bridging the entire Mn(3) triangle similar to the unique carbonyl group in the known compound Cp(3)Nb(3)(CO)(6)(eta(2)-mu(3)-CO). For H(3)Mn(3)(CO)(9) a structure with a central (mu(3)-H)(2)Mn(3) trigonal bipyramid lies >20 kcal/mol below any of the other structures. Triplet structures were found for the unsaturated H(3)Mn(3)(CO)(n) (n = 11, 10, 9) systems but at significantly higher energies than the lowest lying singlet structures.

  16. Electronic origin of the dependence of hydrogen bond strengths on nearest-neighbor and next-nearest-neighbor hydrogen bonds in polyhedral water clusters (H2O)n, n = 8, 20 and 24

    Energy Technology Data Exchange (ETDEWEB)

    Iwata, Suehiro; Akase, Dai; Aida, Misako; Xantheas, Sotiris S.


    The relative stability and the characteristics of the hydrogen bond networks in the cubic cages of (H2O)8, dodecahedral cages of (H2O)20,and tetrakaidodecahedral cages of (H2O)24 are studied. The charge-transfer and dispersion interaction terms of every pair of the hydrogen bonds are evaluated by using the perturbation theory based on the locally-projected molecular orbital (LPMO PT). Every water molecule and every hydrogen-bonded pair in polyhedral clusters are classified by the types of the adjacent molecules and hydrogen bonds. The relative binding energies among the polyhedral clusters are grouped by these classifications. The necessary condition for the stable conformers and the rules of the ordering of the relative stability among the isomers are derived from the analysis. The O–O distances and the pair-wise charge-transfer terms are dependent not only on the types of the hydrogen donor and acceptor waters but also on the types of the adjacent waters. This dependence is analyzed with Mulliken’s charge-transfer theory. The work is partially supported by the Grant-in-Aid for Science Research of JSPS (SI, DA, MA). SSX was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Battelle operates the Pacific Northwest National Laboratory for the US Department of Energy.

  17. Evidence for a cubic-to-icosahedral transition of quasi-free Pd-H-clusters controlled by the hydrogen content . On the phase transitions in Pd-H-clusters (United States)

    Pundt, A.; Dornheim, M.; Guerdane, M.; Teichler, H.; Ehrenberg, H.; Reetz, M. T.; Jisrawi, N. M.


    An in situ synchrotron radiation study of quasi-free five nanometer-sized palladium clusters during hydrogen absorption is combined with molecular dynamics simulations to investigate the structural development. In the diffraction patterns, strong intensity changes are found that provide evidence for a structural phase transformation that is significantly different from the α α' Pd H bulk phase transition. The structural transition is reversible and driven by the hydrogen concentration. The intensity changes are consistent with a cubic-to-icosahedral structural phase transition obtained in molecular dynamical simulations using embedded-atom-method potentials.

  18. Pd clusters supported on amorphous, low-porosity carbon spheres for hydrogen production from formic acid. (United States)

    Bulushev, Dmitri A; Bulusheva, Lyubov G; Beloshapkin, Sergey; O'Connor, Thomas; Okotrub, Alexander V; Ryan, Kevin M


    Amorphous, low-porosity carbon spheres on the order of a few micrometers in size were prepared by carbonization of squalane (C30H62) in supercritical CO2 at 823 K. The spheres were characterized and used as catalysts' supports for Pd. Near-edge X-ray absorption fine structure studies of the spheres revealed sp(2) and sp(3) hybridized carbon. To activate carbons for interaction with a metal precursor, often oxidative treatment of a support is needed. We showed that boiling of the obtained spheres in 28 wt % HNO3 did not affect the shape and bulk structure of the spheres, but led to creation of a considerable amount of surface oxygen-containing functional groups and increase of the content of sp(2) hybridized carbon on the surface. This carbon was seen by scanning transmission electron microscopy in the form of waving graphene flakes. The H/C atomic ratio in the spheres was relatively high (0.4) and did not change with the HNO3 treatment. Palladium was deposited by impregnation with Pd acetate followed by reduction in H2. This gave uniform Pd clusters with a size of 2-4 nm. The Pd supported on the original C spheres showed 2-3 times higher catalytic activity in vapor phase formic acid decomposition and higher selectivity for H2 formation (98-99%) than those for the catalyst based on the HNO3 treated spheres. Using of such low-porosity spheres as a catalyst support should prevent mass transfer limitations for fast catalytic reactions.

  19. Highly efficient visible-light-driven photocatalytic hydrogen production of CdS-cluster-decorated graphene nanosheets. (United States)

    Li, Qin; Guo, Beidou; Yu, Jiaguo; Ran, Jingrun; Zhang, Baohong; Yan, Huijuan; Gong, Jian Ru


    The production of clean and renewable hydrogen through water splitting using photocatalysts has received much attention due to the increasing global energy crises. In this study, a high efficiency of the photocatalytic H(2) production was achieved using graphene nanosheets decorated with CdS clusters as visible-light-driven photocatalysts. The materials were prepared by a solvothermal method in which graphene oxide (GO) served as the support and cadmium acetate (Cd(Ac)(2)) as the CdS precursor. These nanosized composites reach a high H(2)-production rate of 1.12 mmol h(-1) (about 4.87 times higher than that of pure CdS nanoparticles) at graphene content of 1.0 wt % and Pt 0.5 wt % under visible-light irradiation and an apparent quantum efficiency (QE) of 22.5% at wavelength of 420 nm. This high photocatalytic H(2)-production activity is attributed predominantly to the presence of graphene, which serves as an electron collector and transporter to efficiently lengthen the lifetime of the photogenerated charge carriers from CdS nanoparticles. This work highlights the potential application of graphene-based materials in the field of energy conversion.

  20. A DFT Study of CO2 Hydrogenation on Faujasite‐Supported Ir4 Clusters: on the Role of Water for Selectivity Control (United States)

    Smykowski, Daniel; Szczygieł, Jerzy; Hensen, Emiel J. M.


    Abstract Reaction mechanisms for the catalytic hydrogenation of CO2 by faujasite‐supported Ir4 clusters were studied by periodic DFT calculations. The reaction can proceed through two alternative paths. The thermodynamically favoured path results in the reduction of CO2 to CO, whereas the other, kinetically preferred channel involves CO2 hydrogenation to formic acid under water‐free conditions. Both paths are promoted by catalytic amounts of water confined inside the zeolite micropores with a stronger promotion effect for the reduction path. Co‐adsorbed water facilitates the cooperation between the zeolite Brønsted acid sites and Ir4 cluster by opening low‐energy reaction channels for CO2 conversion. PMID:27840663

  1. Selective Propene Epoxidation on Immobilized Au6-10 Clusters: The Effect of Hydrogen and Water on Activity and Selectivity

    DEFF Research Database (Denmark)

    Lee, Sungsik; Molina, Luis M.; López, María J.


    Epoxidation made easy: Subnanometer gold clusters immobilized on amorphous alumina result in a highly active and selective catalyst for propene epoxidation. The highest selectivity is found for gas mixtures involving oxygen and water, thus avoiding the use of hydrogen. Ab initio DFT calculations...... are used to identify key reaction intermediates and reaction pathways. The results confirm the high catalyst activity owing to the formation of propene oxide metallacycles. Al green, Au yellow, O red, and C gray....

  2. Proximity gettering of C3H5 carbon cluster ion-implanted silicon wafers for CMOS image sensors: Gettering effects of transition metal, oxygen, and hydrogen impurities (United States)

    Kurita, Kazunari; Kadono, Takeshi; Okuyama, Ryousuke; Hirose, Ryo; Onaka-Masada, Ayumi; Koga, Yoshihiro; Okuda, Hidehiko


    A new technique is described for manufacturing silicon wafers with the highest capability yet reported for gettering transition metallic, oxygen, and hydrogen impurities in CMOS image sensor fabrication. It is demonstrated that this technique can implant wafers simultaneously with carbon and hydrogen elements that form the projection range by using hydrocarbon compounds. Furthermore, these wafers can getter oxygen impurities out-diffused from the silicon substrate to the carbon cluster ion projection range during heat treatment. Therefore, they can reduce the formation of transition metals and oxygen-related defects in the device active regions and improve electrical performance characteristics, such as dark current and image lag characteristics. The new technique enables the formation of high-gettering-capability sinks for transition metals, oxygen, and hydrogen impurities under device active regions of CMOS image sensors. The wafers formed by this technique have the potential to significantly reduce dark current in advanced CMOS image sensors.

  3. Luminescent properties of aluminum hydride

    Energy Technology Data Exchange (ETDEWEB)

    Baraban, A.P.; Gabis, I.E.; Dmitriev, V.A. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Dobrotvorskii, M.A., E-mail: [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Kuznetsov, V.G. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation); Matveeva, O.P. [National Mineral Resources University, Saint Petersburg 199106 (Russian Federation); Titov, S.A. [Petersburg State University of Railway Transport, Saint-Petersburg 190031 (Russian Federation); Voyt, A.P.; Elets, D.I. [Saint-Petersburg State University, Department of Physics, Saint-Petersburg 198504 (Russian Federation)


    We studied cathodoluminescence and photoluminescence of α-AlH{sub 3}– a likely candidate for use as possible hydrogen carrier in hydrogen-fueled vehicles. Luminescence properties of original α-AlH{sub 3} and α-AlH{sub 3} irradiated with ultraviolet were compared. The latter procedure leads to activation of thermal decomposition of α-AlH{sub 3} and thus has a practical implementation. We showed that the original and UV-modified aluminum hydride contain luminescence centers ‐ structural defects of the same type, presumably hydrogen vacancies, characterized by a single set of characteristic bands of radiation. The observed luminescence is the result of radiative intracenter relaxation of the luminescence center (hydrogen vacancy) excited by electrons or photons, and its intensity is defined by the concentration of vacancies, and the area of their possible excitation. UV-activation of the dehydrogenation process of aluminum hydride leads to changes in the spatial distribution of the luminescence centers. For short times of exposure their concentration increases mainly in the surface regions of the crystals. At high exposures, this process extends to the bulk of the aluminum hydride and ends with a decrease in concentration of luminescence centers in the surface region. - Highlights: • Aluminum hydride contains hydrogen vacancies which serve as luminescence centers. • The luminescence is the result of radiative relaxation of excited centers. • Hydride UV-irradiation alters distribution and concentration of luminescence centers.

  4. Hydrogen activation, diffusion, and clustering on CeO{sub 2}(111): A DFT+U study

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Torre, Delia [Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Instituto de Estructura de la Materia, CSIC, C/ Serrano 121, E-28006 Madrid (Spain); Carrasco, Javier [CIC Energigune, Albert Einstein 48, 01510 Miñano, Álava (Spain); Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie 2, E-28049 Madrid (Spain); Ganduglia-Pirovano, M. Verónica [Instituto de Catálisis y Petroleoquímica, CSIC, C/ Marie Curie 2, E-28049 Madrid (Spain); Pérez, Rubén, E-mail: [Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid (Spain)


    We present a comprehensive density functional theory+U study of the mechanisms underlying the dissociation of molecular hydrogen, and diffusion and clustering of the resulting atomic species on the CeO{sub 2}(111) surface. Contrary to a widely held view based solely on a previous theoretical prediction, our results show conclusively that H{sub 2} dissociation is an activated process with a large energy barrier ∼1.0 eV that is not significantly affected by coverage or the presence of surface oxygen vacancies. The reaction proceeds through a local energy minimum – where the molecule is located close to one of the surface oxygen atoms and the H–H bond has been substantially weaken by the interaction with the substrate –, and a transition state where one H atom is attached to a surface O atom and the other H atom sits on-top of a Ce{sup 4+} ion. In addition, we have explored how several factors, including H coverage, the location of Ce{sup 3+} ions as well as the U value, may affect the chemisorption energy and the relative stability of isolated OH groups versus pair and trimer structures. The trimer stability at low H coverages and the larger upward relaxation of the surface O atoms within the OH groups are consistent with the assignment of the frequent experimental observation by non-contact atomic force and scanning tunneling microscopies of bright protrusions on three neighboring surface O atoms to a triple OH group. The diffusion path of isolated H atoms on the surface goes through the adsorption on-top of an oxygen in the third atomic layer with a large energy barrier of ∼1.8 eV. Overall, the large energy barriers for both, molecular dissociation and atomic diffusion, are consistent with the high activity and selectivity found recently in the partial hydrogenation of acetylene catalyzed by ceria at high H{sub 2}/C{sub 2}H{sub 2} ratios.

  5. WSRT Ultra-Deep Neutral Hydrogen Imaging of Galaxy Clusters at z=0.2, a Pilot Survey of Abell 963 and Abell 2192

    CERN Document Server

    Verheijen, Marc A W; Szomoru, A; Dwarakanath, K S; Poggianti, B M; Schiminovich, D


    A pilot study with the powerful new backend of the Westerbork Synthesis Radio Telescope (WSRT) of two galaxy clusters at z=0.2 has revealed neutral hydrogen emission from 42 galaxies. The WSRT probes a total combined volume of 3.4x10^4 Mpc^3 at resolutions of 54x86 kpc^2 and 19.7 km/s, surveying both clusters and the large scale structure in which they are embedded. In Abell 963, a dynamically relaxed, lensing Butcher-Oemler cluster with a high blue fraction, most of the gas-rich galaxies are located between 1 and 3 Mpc in projection, northeast from the cluster core. Their velocities are slightly redshifted with respect to the cluster, and this is likely a background group. None of the blue galaxies in the core of Abell 963 are detected in HI, although they have similar colors and luminosities as the HI detected galaxies in the cluster outskirts and field. Abell 2192 is less massive and more diffuse. Here, the gas-rich galaxies are more uniformly distributed. The detected HI masses range from 5x10^9 to 4x10^1...

  6. Tracking Rh Atoms in Zeolite HY: First Steps of Metal Cluster Formation and Influence of Metal Nuclearity on Catalysis of Ethylene Hydrogenation and Ethylene Dimerization

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Dong; Xu, Pinghong; Browning, Nigel D.; Gates, Bruce C.


    The initial steps of rhodium cluster formation from zeolite-supported mononuclear Rh(C2H4)2 complexes in H2 at 373 K and 1 bar were investigated by infrared and extended X-ray absorption fine structure spectroscopies and scanning transmission electron microscopy (STEM). The data show that ethylene ligands on the rhodium react with H2 to give supported rhodium hydrides and trigger the formation of rhodium clusters. STEM provided the first images of the smallest rhodium clusters (Rh2) and their further conversion into larger clusters. The samples were investigated in a plug-flow reactor as catalysts for the conversion of ethylene + H2 in a molar ratio of 4:1 at 1 bar and 298 K, with the results showing how the changes in catalyst structure affect the activity and selectivity; the rhodium clusters are more active for hydrogenation of ethylene than the single-site complexes, which are more selective for dimerization of ethylene to give butenes

  7. Hydride mobility in trinuclear sulfido clusters with the core [Rh3(μ-H)(μ3-S)2]: molecular models for hydrogen migration on metal sulfide hydrotreating catalysts. (United States)

    Jiménez, M Victoria; Lahoz, Fernando J; Lukešová, Lenka; Miranda, José R; Modrego, Francisco J; Nguyen, Duc H; Oro, Luis A; Pérez-Torrente, Jesús J


    The treatment of [{Rh(μ-SH){P(OPh)(3)}(2)}(2)] with [{M(μ-Cl)(diolef)}(2)] (diolef=diolefin) in the presence of NEt(3) affords the hydrido-sulfido clusters [Rh(3)(μ-H)(μ(3)-S)(2)(diolef){P(OPh)(3)}(4)] (diolef=1,5-cyclooctadiene (cod) for 1, 2,5-norbornadiene (nbd) for 2, and tetrafluorobenzo[5,6]bicyclo[2.2.2]octa-2,5,7-triene (tfb) for 3) and [Rh(2)Ir(μ-H)(μ(3)-S)(2)(cod){P(OPh)(3)}(4)] (4). Cluster 1 can be also obtained by treating [{Rh(μ-SH){P(OPh)(3)}(2)}(2)] with [{Rh(μ-OMe)(cod)}(2)], although the main product of the reaction with [{Ir(μ-OMe)(cod)}(2)] was [RhIr(2)(μ-H)(μ(3)-S)(2)(cod)(2){P(OPh)(3)}(2)] (5). The molecular structures of clusters 1 and 4 have been determined by X-ray diffraction methods. The deprotonation of a hydrosulfido ligand in [{Rh(μ-SH)(CO)(PPh(3))}(2)] by [M(acac)(diolef)] (acac=acetylacetonate) results in the formation of hydrido-sulfido clusters [Rh(3)(μ-H)(μ(3)-S)(2)(CO)(2) (diolef)(PPh(3))(2)] (diolef=cod for 6, nbd for 7) and [Rh(2)Ir(μ-H)(μ(3)-S)(2)(CO)(2)(cod)(PPh(3))(2)] (8). Clusters 1-3 and 5 exist in solution as two interconverting isomers with the bridging hydride ligand at different edges. Cluster 8 exists as three isomers that arise from the disposition of the PPh(3) ligands in the cluster (cis and trans) and the location of the hydride ligand. The dynamic behaviour of clusters with bulky triphenylphosphite ligands, which involves hydrogen migration from rhodium to sulfur with a switch from hydride to proton character, is significant to understand hydrogen diffusion on the surface of metal sulfide hydrotreating catalysts.

  8. Deletion of a gene cluster for [Ni-Fe] hydrogenase maturation in the anaerobic hyperthermophilic bacterium Caldicellulosiruptor bescii identifies its role in hydrogen metabolism. (United States)

    Cha, Minseok; Chung, Daehwan; Westpheling, Janet


    The anaerobic, hyperthermophlic, cellulolytic bacterium Caldicellulosiruptor bescii grows optimally at ∼80 °C and effectively degrades plant biomass without conventional pretreatment. It utilizes a variety of carbohydrate carbon sources, including both C5 and C6 sugars, released from plant biomass and produces lactate, acetate, CO2, and H2 as primary fermentation products. The C. bescii genome encodes two hydrogenases, a bifurcating [Fe-Fe] hydrogenase and a [Ni-Fe] hydrogenase. The [Ni-Fe] hydrogenase is the most widely distributed in nature and is predicted to catalyze hydrogen production and to pump protons across the cellular membrane creating proton motive force. Hydrogenases are the key enzymes in hydrogen metabolism and their crystal structure reveals complexity in the organization of their prosthetic groups suggesting extensive maturation of the primary protein. Here, we report the deletion of a cluster of genes, hypABFCDE, required for maturation of the [Ni-Fe] hydrogenase. These proteins are specific for the hydrogenases they modify and are required for hydrogenase activity. The deletion strain grew more slowly than the wild type or the parent strain and produced slightly less hydrogen overall, but more hydrogen per mole of cellobiose. Acetate yield per mole of cellobiose was increased ∼67 % and ethanol yield per mole of cellobiose was decreased ∼39 %. These data suggest that the primary role of the [Ni-Fe] hydrogenase is to generate a proton gradient in the membrane driving ATP synthesis and is not the primary enzyme for hydrogen catalysis. In its absence, ATP is generated from increased acetate production resulting in more hydrogen produced per mole of cellobiose.

  9. Hydrogen evolution reaction catalyst (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan


    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  10. Cluster-assisted generation of multi-charged ions in nanosecond laser ionization of pulsed hydrogen sulfide beam at 1064 and 532 nm

    Institute of Scientific and Technical Information of China (English)

    Niu Dong-Mei; Li Hai-Yang; Luo Xiao-Lin; Liang Feng; Cheng Shuang; Li An-Lin


    The multi-charged sulfur ions of Sq+ (q ≤ 6) have been generated when hydrogen sulfide cluster beams are irradiated by a nanosecond laser of 1064 and 532 nm with an intensity of 1010 ~ 1012W·cm-2. S6+ is the dominant multicharged species at 1064 nm, while S4+, S3+ and S2+ ions are the main multi-charged species at 532 nm. A three-step model (i.e., multiphoton ionization triggering, inverse bremsstrahlung heating, electron collision ionizing) is proposed to explain the generation of these multi-charged ions at the laser intensity stated above. The high ionization level of the clusters and the increasing charge state of the ion products with increasing laser wavelength are supposed mainly due to the rate-limiting step, i.e., electron heating by absorption energy from the laser field via inverse bremsstrahlung, which is proportional to λ2, λ being the laser wavelength.

  11. Neutral hydrogen gas, past and future star formation in galaxies in and around the `Sausage' merging galaxy cluster (United States)

    Stroe, Andra; Oosterloo, Tom; Röttgering, Huub J. A.; Sobral, David; van Weeren, Reinout; Dawson, William


    CIZA J2242.8+5301 (z = 0.188, nicknamed `Sausage') is an extremely massive (M200 ˜ 2.0 × 1015 M⊙), merging cluster with shock waves towards its outskirts, which was found to host numerous emission line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope H I observations of the `Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission line galaxies in the `Sausage' cluster have, on average, as much H I gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large H I reservoirs are expected to be consumed within ˜0.75-1.0 Gyr by the vigorous SF and active galactic nuclei activity and/or driven out by the outflows we observe. We find that the star formation rate (SFR) in a large fraction of H α emission line cluster galaxies correlates well with the radio broad-band emission, tracing supernova remnant emission. This suggests that the cluster galaxies, all located in post-shock regions, may have been undergoing sustained SFR for at least 100 Myr. This fully supports the interpretation proposed by Stroe et al. and Sobral et al. that gas-rich cluster galaxies have been triggered to form stars by the passage of the shock.

  12. Aluminum alloy (United States)

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


    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.

  13. Does the MgO(100)-support facilitate the reaction of nitrogen and hydrogen molecules catalyzed by Zr2Pd2 clusters? A computational study. (United States)

    Kuznetsov, Aleksey E; Musaev, Djamaladdin G


    Reactions of the "naked" and MgO(100) supported Zr(2)Pd(2) cluster with nitrogen and four hydrogen molecules were studied at the density functional level using the periodic slab approach (VASP). It was shown that adsorption of the Zr(2)Pd(2) cluster on the MgO(100) surface does not change its gas-phase geometry and electronic structure significantly. In spite of this the N(2) coordination to the MgO(100)-supported Zr(2)Pd(2) cluster, I/MgO, is found to be almost 30 kcal/mol less favorable than for the "naked" one. The addition of the first H(2) molecule to the resulting II/MgO, that is, II/MgO + H(2) --> IV/MgO reaction, proceeds with a relatively small, 9.0 kcal/mol, barrier and is exothermic by 8.3 kcal/mol. The same reaction for the "naked" Zr(2)Pd(2) cluster requires a slightly larger barrier (10.1 kcal/mol) and is highly exothermic (by 23.3 kcal/mol). The interaction of the H(2) molecule with the intermediate IV/MgO (i.e., the second H(2) molecule addition to II/MgO) requires larger energy barrier, 23.3 kcal/mol vs 8.8 kcal/mol for the "naked" cluster, and is exothermic by 20.5 kcal/mol (vs 18.2 kcal/mol reported for the "naked" Zr(2)Pd(2) cluster). The addition of the H(2) molecule to VI/MgO and VI (i.e., the third H(2) molecule addition to II/MgO and II, respectively) requires similar barriers, 12.0 versus 16.8 kcal/mol, respectively, but is highly exothermic for the supported cluster compared to the "naked" one, 13.6 versus 0.1 kcal/mol. The addition of the fourth H(2) molecule occurs with almost twice larger barrier for the "naked" cluster compared to the adsorbed species, 30.7 versus 15.9 kcal/mol. Furthermore, this reaction step is endothermic (by 11.4 kcal/mol) for the gas-phase cluster but exothermic by 7.8 kcal/mol for the adsorbed cluster. Dissociation of the formed hydrazine molecule from the on-surface complex X/MgO and the "naked" complex X requires 19.1 and 26.3 kcal/mol, respectively. Thus, the Zr(2)Pd(2) adsorption on the MgO(100) surface

  14. Neutral hydrogen gas, past and future star-formation in galaxies in and around the 'Sausage' merging galaxy cluster

    CERN Document Server

    Stroe, Andra; Rottgering, Huub J A; Sobral, David; van Weeren, Reinout; Dawson, William


    CIZA J2242.8+5301 ($z = 0.188$, nicknamed 'Sausage') is an extremely massive ($M_{200}\\sim 2.0 \\times 10^{15}M_\\odot$ ), merging cluster with shock waves towards its outskirts, which was found to host numerous emission-line galaxies. We performed extremely deep Westerbork Synthesis Radio Telescope HI observations of the 'Sausage' cluster to investigate the effect of the merger and the shocks on the gas reservoirs fuelling present and future star formation (SF) in cluster members. By using spectral stacking, we find that the emission-line galaxies in the 'Sausage' cluster have, on average, as much HI gas as field galaxies (when accounting for the fact cluster galaxies are more massive than the field galaxies), contrary to previous studies. Since the cluster galaxies are more massive than the field spirals, they may have been able to retain their gas during the cluster merger. The large HI reservoirs are expected to be consumed within $\\sim0.75-1.0$ Gyr by the vigorous SF and AGN activity and/or driven out by t...

  15. Rhodium based clusters for oxygen reduction and hydrogen oxidation in 0.5 M H2SO4, tolerant to methanol and carbon monoxide, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Jimenez-Sandoval, O.; Borja-Arco, E.; Altamirano-Gutierrez, A. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Queritaro (Mexico); Castellanos, R.H. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Queretaro, Queretaro (Mexico)


    Rhodium (Rh6(CO)16) and novel Rh-based clusters were prepared using thermolysis techniques under different conditions in N2 and H2 reaction media, as well as in n-nonane, o-xylene, 1,2-dichlorobenzene and dimethylsulfoxide. The clusters were used as novel electrocatalysts for oxygen reduction reaction (ORR) in the absence and presence of 1.0 and 2.0 M methanol solutions. The catalysts were also used for hydrogen oxidation reaction (HOR) with pure hydrogen (H2) and in the presence of carbon monoxide (CO). Rotating disk electrode measurements were used to analyze the materials. The study showed that the electrocatalyst support ratio plays a significant role in the electrochemical behaviour of the materials. Rh6(CO)16 and Rh2(1,2-DCB) presented the best electrocatalytic behaviour for ORR and HOR in the absence and presence of methanol and CO. The study demonstrated that the rhodium-based materials are capable of performing ORR and HOR while being tolerant of both methanol and CO. 3 refs., 3 figs.

  16. Aluminum-induced cell death of barley-root border cells is correlated with peroxidase- and oxalate oxidase-mediated hydrogen peroxide production. (United States)

    Tamás, L; Budíková, S; Huttová, J; Mistrík, I; Simonovicová, M; Siroká, B


    The function of root border cells (RBC) during aluminum (Al) stress and the involvement of oxalate oxidase, peroxidase and H(2)O(2) generation in Al toxicity were studied in barley roots. Our results suggest that RBC effectively protect the barley root tip from Al relative to the situation in roots cultivated in hydroponics where RBC are not sustained in the area surrounding the root tip. The removal of RBC from Al-treated roots increased root growth inhibition, Al and Evans blue uptake, inhibition of RBC production, the level of dead RBC, peroxidase and oxalate oxidase activity and the production of H(2)O(2). Our results suggest that even though RBC actively produce active oxygen species during Al stress, their role in the protection of root tips against Al toxicity is to chelate Al in their dead cell body.

  17. Cluster-cluster clustering (United States)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C. S.


    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales.

  18. Cluster-cluster clustering

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.


    The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references.

  19. 硫化氢缓解铝胁迫对水稻幼苗叶片抗氧化系统的调控%Alleviation of Exogenous Hydrogen Sulfide on Rice Seedlings to Aluminum Stress

    Institute of Scientific and Technical Information of China (English)

    孟丹; 安敏敏; 杨立明


    Hydrogen sulfide (H2S), an important signal molecular in plants, can alleviate the toxicity of metal stress to crops. In this study, the effects of H2 S donor NaHS alleviating AlCl3-induced stress were con-ducted in the leaves of rice seedlings. We examined the metabolic responses of rice seedlings to aluminum stress focusing on reactive oxygen species ( ROS) metabolism including superoxide dismutase and catalase ac-tivity. The observed enzyme activities were higher in aluminum-stressed seedlings than in control plants, NaHS decreased the activities of superoxide dismutase and catalase, and the contents of superoxide radical and hy-drogen peroxide. Taken together these results suggest that H2 S could regulate antioxidant system in rice seed-lings leading to the alleviation of iluminum stress.%硫化氢( H2 S)是植物体内重要的信号分子,可显著缓解重金属对水稻的毒害.以硫氢化钠(NaHS)作为硫化氢的供体,分别采用0.4 mmol/L NaHS,75μmol/L AlCl3,75μmol/L AlCl3+0.4 mmol/L NaHS处理水稻幼苗,测定H2 S对水稻幼苗内氧化还原系统的影响.结果表明,铝胁迫显著增加了水稻幼苗体内过氧化氢和超氧阴离子的含量,以及超氧化物歧化酶( SOD),过氧化氢酶( CAT)等活性氧清除酶系的活性,而施加H2 S供体NaHS显著降低了过氧化氢和超氧阴离子的含量,以及SOD和CAT的活性.

  20. Aluminum/air electrochemical cells


    Wang, Lei; 王雷


    Aluminum (Al) is a very promising energy carrier given its high capacity and energy density, low cost, earth abundance and environmental benignity. The Al/air battery as a kind of metal/air electrochemical cell attracts tremendous attention. Traditional Al/air batteries suffer from the self-corrosion and related safety problems. In this work, three new approaches were investigated to tackle these challenges and to develop high-performance Al/air cells: (1) incorporate an additional hydrogen/a...

  1. Assembly of organic moiety with metal-oxide cluster to generate a new three dimensional supramolecular/hydrogen bonded network based on isopolymolybdate

    Indian Academy of Sciences (India)



    A new octa-molybdate formulated as (C₂H₆N₄)₂ [β-Mo₈O₂₆].4H₂O (1) has been isolated by conventional solution method and structurally characterized by single-crystal X-ray diffraction method, IR spectroscopy, UV-Vis absorption, thermogravimetric analysis and cyclic voltammetry. Compound 1 crystallizes in the Triclinic system, space group P-1 with unit cell dimensions, a = 8.348 (2)Å, b = 10.154 (2)Å, c = 10.823 (3)Å, α = 68.35◦ (2), β = 71.59◦ (2), γ= 78.55◦ (2), V = 805.5 (3)ų, and Z = 2. The crystal structure of 1 is built up from octa-molybdate [β-Mo₈O₂₆]⁴⁻ clusters connected through hydrogen-bonding interactions into a three-dimensional supramolecular network.

  2. Control in the Rate-Determining Step Provides a Promising Strategy To Develop New Catalysts for CO2 Hydrogenation: A Local Pair Natural Orbital Coupled Cluster Theory Study. (United States)

    Mondal, Bhaskar; Neese, Frank; Ye, Shengfa


    The development of efficient catalysts with base metals for CO2 hydrogenation has always been a major thrust of interest. A series of experimental and theoretical work has revealed that the catalytic cycle typically involves two key steps, namely, base-promoted heterolytic H2 splitting and hydride transfer to CO2, either of which can be the rate-determining step (RDS) of the entire reaction. To explore the determining factor for the nature of RDS, we present herein a comparative mechanistic investigation on CO2 hydrogenation mediated by [M(H)(η(2)-H2)(PP3(Ph))](n+) (M = Fe(II), Ru(II), and Co(III); PP3(Ph) = tris(2-(diphenylphosphino)phenyl)phosphine) type complexes. In order to construct reliable free energy profiles, we used highly correlated wave function based ab initio methods of the coupled cluster type alongside the standard density functional theory. Our calculations demonstrate that the hydricity of the metal-hydride intermediate generated by H2 splitting dictates the nature of the RDS for the Fe(II) and Co(III) systems, while the RDS for the Ru(II) catalyst appears to be ambiguous. CO2 hydrogenation catalyzed by the Fe(II) complex that possesses moderate hydricity traverses an H2-splitting RDS, whereas the RDS for the high-hydricity Co(III) species is found to be the hydride transfer. Thus, our findings suggest that hydricity can be used as a practical guide in future catalyst design. Enhancing the electron-accepting ability of low-hydricity catalysts is likely to improve their catalytic performance, while increasing the electron-donating ability of high-hydricity complexes may speed up CO2 conversion. Moreover, we also established the active roles of base NEt3 in directing the heterolytic H2 splitting and assisting product release through the formation of an acid-base complex.

  3. Anticooperativity of FHF hydrogen bonds in clusters of the type F- × (HF)n, RF × (HF)n and XF × (HF)n, R = alkyl and X = H, Br, Cl, F (United States)

    Kucherov, S. Yu.; Bureiko, S. F.; Denisov, G. S.


    Properties of twenty five hydrogen-bonded complexes, namely, F- × (HF)n (n = 1-6), RF × (HF)n (R = t-Bu, i-Pr, Et, Me; n = 1-3), XF × (HF)n (X = H, Br, Cl; n = 1-2), and FF…HF with the hydrogen bond energy varying in a wide range have been calculated using ab initio methods at the MP2/6-31++G** level. For the first time, the energies, geometrical parameters and vibrational frequencies are obtained for the series of clusters, where the bonding character changes from covalent to van der Waals on the variation of proton-acceptor ability of the base, and the energies are in the range of 45-1 kcal/mol. The mutual influence of multiple hydrogen bonds of F…HF type in clusters, in which a fluorine anion or an atom participates in hydrogen bond formation as the acceptor, is systematically investigated. The relative changes in the values of the considered parameters on the sequential addition of an HF molecule (anticooperativity) were determined. It was shown that non-additivity of the interaction is most strongly pronounced in the energy and vibrational frequency values, geometrical parameters of hydrogen bonds are less sensitive to the mutual influence. The anticooperative effect is more pronounced on the hydrogen bridge length R(F...F) than on the geometry of proton donor r(HF). The hydrogen bond formation and the increase of the number n of ligands lead to successive lengthening of the r(XF) bond adjacent to the hydrogen bridge. The length of an XF bond changes stronger on formation of each hydrogen bond than the HF bond length.

  4. Effects of co-implanted oxygen or aluminum atoms on hydrogen migration and damage structure in multiple-beam irradiated Al sub 2 O sub 3

    CERN Document Server

    Katano, Y; Yamamoto, S; Nakazawa, T; Yamaki, D; Noda, K


    Depth profiles of implanted H atoms were measured for single crystalline Al sub 2 O sub 3 samples irradiated at 923 K with dual or triple beams of 0.25 MeV H-, 0.6 MeV He-, 2.4 MeV O-ions or 2.6 MeV Al-ions. The peaks occur at 1.55 and 1.45 mu m in the depth profiles measured for the H + Al dual beam irradiation and H + O dual beam case, respectively. The ratio of the peak areas is over 4, which is much larger than the implanted H atom ratio of 1.1, indicating that implanted Al atoms suppress the mobility of H atoms. However, the ratio becomes almost 1 between the triple beam samples with H + He + O-ions and with H + He + Al-ions at comparable doses. The fact demonstrates that implanted He atoms overwhelm the effects of the implanted self-cation/anion excess atoms on the migration behaviors of implanted hydrogen and radiation produced point defects, with the resulting sluggish cavity growth observed.

  5. Simulation of the time dependent infrared nu2 mode absorptions of (oH2)n:H2O clusters in O2 doped solid hydrogen at 4.2 K. (United States)

    Abouaf-Marguin, L; Vasserot, A-M; Pardanaud, C


    Using Fourier transform infrared spectroscopy, we have analyzed the time evolution of the nu(2) mode of (oH(2))(n):H(2)O clusters (n = 11 to 1) embedded in solid normal hydrogen at 4.2 K over a period of 150 h using paramagnetic O(2) to speed up the ortho to para nuclear spin conversion process. For concentrations H(2)O/O(2)/H(2) = 1/20/4000, at time t = 0 right after the solid is prepared, all the H(2)O molecules are preferentially clustered by large numbers of oH(2). With time the cluster distribution irreversibly shifts toward smaller cluster sizes and also generates freely rotating H(2)O (n = 0) which is solvated completely by pH(2) molecules. From a spectral decomposition of the nu(2) (oH(2))(n):H(2)O cluster spectra, a phenomenological simulation of the time behavior of the clusters has been developed. The time evolution is modeled using coupled rate equations in a step by step n to n-1 cluster cascade fashion and analyzed over nine successive time periods. It shows that rotating H(2)O grows only at the expense of cluster n = 1 and that the process dramatically slows down as the conversion of orthohydrogen proceeds. At the end of the conversion process, it was found that cluster n = 1 remained with a very slow decrease.

  6. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    Directory of Open Access Journals (Sweden)

    Jun-qin Wang


    Full Text Available The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that the product through this synthesis method is sodium aluminum hydride, and it has higher purity, perfect crystal character, better stability, and good hydrogen storage property. The reaction mechanism is also discussed in detail.

  7. Inhibition of aluminum corrosion using Opuntia extract

    Energy Technology Data Exchange (ETDEWEB)

    El-Etre, A.Y


    The inhibitive action of the mucilage extracted from the modified stems of prickly pears, toward acid corrosion of aluminum, is tested using weight loss, thermometry, hydrogen evolution and polarization techniques. It was found that the extract acts as a good corrosion inhibitor for aluminum corrosion in 2.0 M HCl solution. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. It was found that the adsorption of the extract on aluminum surface is a spontaneous process. The inhibition efficiency (IE) increases as the extract concentration is increased. The effect of temperature on the IE was studied. It was found that the presence of extract increases the activation energy of the corrosion reaction. Moreover, the thermodynamic parameters of the adsorption process were calculated. It was found also that the Opuntia extract provides a good protection to aluminum against pitting corrosion in chloride ion containing solutions.

  8. An early response regulatory cluster induced by low temperature and hydrogen peroxide in seedlings of chilling-tolerant japonica rice

    Directory of Open Access Journals (Sweden)

    Jia Yulin


    Full Text Available Abstract Background Plants respond to low temperature through an intricately coordinated transcriptional network. The CBF/DREB-regulated network of genes has been shown to play a prominent role in freeze-tolerance of Arabidopsis through the process of cold acclimation (CA. Recent evidence also showed that the CBF/DREB regulon is not unique to CA but evolutionarily conserved between chilling-insensitive (temperate and chilling-sensitive (warm-season plants. In this study, the wide contrast in chilling sensitivity between indica and japonica rice was used as model to identify other regulatory clusters by integrative analysis of promoter architecture (ab initio and gene expression profiles. Results Transcriptome analysis in chilling tolerant japonica rice identified a subset of 121 'early response' genes that were upregulated during the initial 24 hours at 10°C. Among this group were four transcription factors including ROS-bZIP1 and another larger sub-group with a common feature of having as1/ocs-like elements in their promoters. Cold-induction of ROS-bZIP1 preceded the induction of as1/ocs-like element-containing genes and they were also induced by exogenous H2O2 at ambient temperature. Coordinated expression patterns and similar promoter architectures among the 'early response' genes suggest that they belong to a potential regulon (ROS-bZIP – as1/ocs regulatory module that responds to elevated levels of ROS during chilling stress. Cultivar-specific expression signatures of the candidate genes indicate a positive correlation between the activity of the putative regulon and genotypic variation in chilling tolerance. Conclusion A hypothetical model of an ROS-mediated regulon (ROS-bZIP – as1/ocs triggered by chilling stress was assembled in rice. Based on the current results, it appears that this regulon is independent of ABA and CBF/DREB, and that its activation has an important contribution in configuring the rapid responses of rice seedlings

  9. Research on Sustainable Development of County Characteristic Industrial Clusters:Case of the Aluminum Processing Industrial Clusters in Gongyi%县域特色产业集群的可持续发展研究——以巩义市铝加工特色产业集群为例

    Institute of Scientific and Technical Information of China (English)



    特色产业集群的发展是区域经济发展的关键动力,其研究应立足于区域经济的实际。巩义市特色产业集群众多,尤其是铝加工产业集群特点鲜明,发展速度很快,但是在其发展过程中也存在着不少的问题。因此,以巩义铝加工特色产业集群为例,在调研其发展现状的基础上,采用SWOT分析法,对其内部的优势、劣势以及外部的机会和威胁进行了分析,在此基础上提出了其可持续发展的策略。%The development of characteristic industrial clusters is the key driving force of regional economic development.The research of characteristic industrial clusters should combine with the actual of regional economy.There are a lot of characteristic industrial clusters in Gongyi.The aluminum processing industrial clusters has distinctive characteristics.It develops rapidly,but there are also a lot of problems in the course of its development.In the case of the aluminum processing industrial clusters in Gongyi,this paper analyzes the strengths,weaknesses,opportunities and threats of industrial cluster by using SWOT method,brings forward some suggestions of sustainable development.

  10. Shijiazhuang will Build the World’s Biggest Replacingcopper-with-aluminum Cable Production Base

    Institute of Scientific and Technical Information of China (English)


    <正>Shijiazhuang City will build the world’s biggest replacing-copper-with-aluminum cable production base,the annual output value can reach 100 billion yuan,in the future it will develop replacing-copper-with-aluminum highend industry cluster.This piece of news was learned by the reporter at the Rare Earth highiron Aluminum Alloy[Nonferrous Business Opportunity:Aluminum alloy door]Cable Conductor New Technology Application Seminar held at the provincial capital.


    Directory of Open Access Journals (Sweden)



    Full Text Available In municipal solid waste, aluminum is the main nonferrous metal, approximately 80- 85% of the total nonferrous metals. The income per ton gained from aluminum recuperation is 20 times higher than from glass, steel boxes or paper recuperation. The object of this paper is the design of a 300 kN press for aluminum box bundling.

  12. Ab initio molecular-orbital study on successive hydrogen-elimination reactions with low activation energies in the a-Si:H formation process: Cluster-size dependence of activation energies (United States)

    Sato, Kota; Honna, Hiroshi; Iwabuchi, Susumu; Hirano, Tsuneo; Koinuma, Hideomi


    Successive hydrogen-elimination reactions with low activation energies during the formation of a-Si:H by silane plasma chemical-vapor deposition proposed by us were studied by using a larger cluster model on the basis of an ab initio molecular-orbital method. The activation energy of the first step, the reaction of a dangling-bond site with an adjacent tetrahedrally coordinated silicon, was found to be 18.2 kcal/mol (0.79 eV) by employing a larger cluster model. The total process was also shown to be thermodynamically more favorable by using larger cluster models. Thus, the successive process is considered to play an important role in a-Si:H formation processes.

  13. Purification technology of molten aluminum

    Institute of Scientific and Technical Information of China (English)

    孙宝德; 丁文江; 疏达; 周尧和


    Various purification methods were explored to eliminate the dissolved hydrogen and nonmetallic inclusions from molten aluminum alloys. A novel rotating impeller head with self-oscillation nozzles or an electromagnetic valve in the gas circuit was used to produce pulse gas currents for the rotary impeller degassing method. Water simulation results show that the size of gas bubbles can be decreased by 10%-20% as compared with the constant gas current mode. By coating ceramic filters or particles with active flux or enamels, composite filters were used to filter the scrap A356 alloy and pure aluminum. Experimental results demonstrate that better filtration efficiency and operation performance can be obtained. Based on numerical calculations, the separation efficiency of inclusions by high frequency magnetic field can be significantly improved by using a hollow cylinder-like separator or utilizing the effects of secondary flow of the melt in a square separator. A multi-stage and multi-media purification platform based on these methods was designed and applied in on-line processing of molten aluminum alloys. Mechanical properties of the processed scrap A356 alloy are greatly improved by the composite purification.

  14. Electronic Structure Investigations of Aluminum Clusters (United States)


    resolved work. The dye laser was calibratcd with optogalvanic spectra obtained from a Fe/Ne hollow cathodc lamp 3, Theoretical calculations Ah...OA?l{y) 1: 󈧏 - A·’A , 3.5l!O 3.1130 0.422 (Y) l;:lh-,jlA, 2.n5 0.367 ()) helium or argon gas (10 bar) provided by a 0.3 mOl orifkc- pulsed valve...resulting AI(2 rodicals nrc then probed through Inser- induced fluorescencc (L1f) using nn excimer -pumped dye laser (0. 15 em - I) with a w<lvcmeter used

  15. Dynamics and fragmentation of van der Waals and hydrogen bonded cluster cations: (NH3)n and (NH3BH3)n ionized at 10.51 eV (United States)

    Yuan, Bing; Shin, Joong-Won; Bernstein, Elliot R.


    description of the valence electron distribution for the various clusters and monomers. Comparison of the present results with those found for solid NH3BH3 suggests that NH3BH3 can be a good hydrogen storage material.

  16. Nanostructures from hydrogen implantation of metals.

    Energy Technology Data Exchange (ETDEWEB)

    McWatters, Bruce Ray (Sandia National Laboratories, Albuquerque, NM); Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.


    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  17. Aspects of aluminum toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Hewitt, C.D.; Savory, J.; Wills, M.R. (Univ. of Virginia Health Sciences Center, Charlottesville (USA))


    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.

  18. Aluminum powder metallurgy processing

    Energy Technology Data Exchange (ETDEWEB)

    Flumerfelt, J.F.


    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.

  19. The corrosion of aluminum in dilute solutions: laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Draley, J.E.; Arendt, J.W.; English, G.C.; Story, E.F.; Wainscott, M.M.; Berger, R.W.


    After it had been decided that aluminum was to be used as a corrosion-resistant material with good heat transfer properties, it was desired to determine the operating conditions to be used in the water-cooled Handford plant in order to avoid danger of corrosion penetration of thin aluminum parts. The studies here reported were undertaken with the object of determining these conditions by investigating the effects of all the known variables which might influence the corrosion behavior of aluminum in a water-coolded plant at HEW. The addition of hydrogen peroxide to the testing solutions was the only effort made to simulate special conditions at the plant.

  20. Initiating, growing and cracking of hydrogen blisters

    Institute of Scientific and Technical Information of China (English)

    REN Xuechong; SHAN Guangbin; CHU Wuyang; SU Yanjing; GAO Kewei; QIAO Lijie; JIANG Bo; CHEN Gang; CUI Yinhui


    The growing process of a hydrogen blister in a wheel steel was observed in situ with an optical microscope, and the fracture surfaces formed from broken blisters on a wheel steel and bulk metallic glass were investigated. The initiating, growing, cracking and breaking of hydrogen blisters are as follows. Supersaturated vacancies can increase greatly during charging and gather together into a vacancy cluster (small cavity). Hydrogen atoms become hydrogen molecules in the vacancy cluster and hydrogen molecules can stabilize the vacancy cluster. The small cavity becomes the nucleus of hydrogen blister. The blister will grow with entering of vacancies and hydrogen atoms. With increasing hydrogen pressure, plastic deformation occurs first, the hydrogen blister near the surface extrudes, and then cracks initiate along the wall of the blister with further increasing hydrogen pressure. A cracked blister can grow further through propagating of cracks until it breaks.

  1. Study of electrocatalytic properties of iridium carbonyl cluster and rhodium carbonyl cluster compounds for the oxygen reduction and hydrogen oxidation reactions in 0.5 MH{sub 2}SO{sub 4} in presence and absence of methanol and carbon monoxide, respectively

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Borja-Arco, E.; Castellanos, R.H. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Escobedo (Mexico); Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Querataro (Mexico)


    The suitability of carbonyl cluster compounds as a substitute to platinum (Pt) in fuel cell catalysts was investigated. Iridium (Ir{sub 4}(CO){sub 12} and rhodium (Rh{sub 6}(CO){sub 116}) cluster compounds were investigated as potential new electrocatalysts for oxygen reduction reaction (ORR) in the presence and absence of methanol at different concentrations, as well as for the hydrogen oxidation reaction (HOR) with pure hydrogen and a hydrogen/carbon monoxide mixture. The materials were studied using room temperature rotating disk electrode (RDE) measurements and cyclic and linear sweep voltammetry techniques (LSV). Tafel slope and exchange current density were calculated using the LSV polarization curves. Cyclic voltamperometry results suggested that the electrocatalysts were tolerant to methanol. However, electrochemical behaviour of the materials altered in the presence of CO, and peaks corresponding to CO oxidation were observed in both cases. The rhodium carbonyl showed a higher current density for the ORR than the iridium carbonyl. The current potential curves in the presence of methanol were similar to those obtained without methanol. Results confirmed the tolerance properties of the materials to perform the ORR. Decreased current density values were observed during HOR, and were attributed to changes in the hydrogen solubility and diffusion coefficient due to the presence of CO. The Tafel slopes indicated that the mechanics of the HOR were Heyrovsky-Volmer. Results showed that the materials are capable of performing both ORR and HOR in an acid medium. It was noted that the iridium carbonyl cluster followed a 4-electron transfer mechanism towards the formation of water. It was concluded that the compounds are suitable for use as both cathodes and anodes in proton exchange membrane fuel cells (PEMFCs) and as cathodes in direct methanol fuel cells (DMFCs). 3 refs., 2 tabs., 3 figs.

  2. A comparative study between all-electron scalar relativistic calculation and all-electron calculation on the adsorption of hydrogen molecule onto small gold clusters

    Indian Academy of Sciences (India)

    Xiang-Jun Kuang; Xin-Qiang Wang; Gao-Bin Liu


    A comparative study between all-electron relativistic (AER) calculation and all-electron (AE) calculation on the H2 molecule adsorption onto small gold clusters has been performed. Compared with the corresponding AuH2 cluster obtained by AE method, the AuH2 cluster obtained by AER method has much shorter Au-H bond-length, much longer H-H distance, larger binding energy and adsorption energy, higher vertical ionization potentials (VIP), greater charge transfer, higher vibrational frequency of Au-H mode and lower vibrational frequency of H-H mode. The delocalization of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) for AuH2 cluster obtained by AER method is obvious. All these characteristics suggest that the scalar relativistic effect might strengthen the Au-H bond and weaken the H-H bond. It is believed that the scalar relativistic effect is favourable to the H2 molecule adsorption onto small gold cluster and the reactivity enhancement of H2 molecule. It may be one of the reasons why the dissociative adsorptions take place in some AuH2 clusters. With increasing size of AuH2 clusters, the influence of scalar relativistic effect becomes more significant. Some further studies focused on the influence of scalar relativistic effect on the adsorption behaviour of other small molecules onto gold clusters are necessary in the future.

  3. Is the Aluminum Hypothesis Dead?


    Lidsky, Theodore I.


    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 w...

  4. High energy density aluminum battery

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  5. Is the Aluminum Hypothesis dead? (United States)

    Lidsky, Theodore I


    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.

  6. Synthesis of Aluminum-Aluminum Nitride Nanocomposites by a Gas-Liquid Reaction II. Microstructure and Mechanical Properties (United States)

    Borgonovo, Cecilia; Makhlouf, Makhlouf M.


    In situ fabrication of the reinforcing particles in the metal matrix is an answer to many of the challenges encountered in manufacturing aluminum matrix nanocomposites. In this method, the nanoparticles are formed directly within the melt by means of a chemical reaction between a specially designed aluminum alloy and a gas. In this publication, we describe a process for synthesizing aluminum-aluminum nitride nanocomposites by reacting a nitrogen-containing gas with a molten aluminum-lithium alloy. We quantify the effect of the process parameters on the average particle size and particle distribution, as well as on the tendency of the particles to cluster in the alloy matrix, is quantified. Also in this publication, we present the measured room temperature and elevated temperature tensile properties of the nanocomposite material as well as its measured room temperature impact toughness.

  7. Anodizing Aluminum with Frills. (United States)

    Doeltz, Anne E.; And Others


    "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…

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

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Joseph A. Megy


    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.

  9. The aluminum smelting process. (United States)

    Kvande, Halvor


    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.

  10. Liquid Hydrogen Absorber for MICE

    Energy Technology Data Exchange (ETDEWEB)

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing


    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  11. Clinical biochemistry of aluminum

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  12. Dimeric [Mo2 S12 ](2-) Cluster: A Molecular Analogue of MoS2 Edges for Superior Hydrogen-Evolution Electrocatalysis. (United States)

    Huang, Zhongjie; Luo, Wenjia; Ma, Lu; Yu, Mingzhe; Ren, Xiaodi; He, Mingfu; Polen, Shane; Click, Kevin; Garrett, Benjamin; Lu, Jun; Amine, Khalil; Hadad, Christopher; Chen, Weilin; Asthagiri, Aravind; Wu, Yiying


    Proton reduction is one of the most fundamental and important reactions in nature. MoS2 edges have been identified as the active sites for hydrogen evolution reaction (HER) electrocatalysis. Designing molecular mimics of MoS2 edge sites is an attractive strategy to understand the underlying catalytic mechanism of different edge sites and improve their activities. Herein we report a dimeric molecular analogue [Mo2 S12 ](2-) , as the smallest unit possessing both the terminal and bridging disulfide ligands. Our electrochemical tests show that [Mo2 S12 ](2-) is a superior heterogeneous HER catalyst under acidic conditions. Computations suggest that the bridging disulfide ligand of [Mo2 S12 ](2-) exhibits a hydrogen adsorption free energy near zero (-0.05 eV). This work helps shed light on the rational design of HER catalysts and biomimetics of hydrogen-evolving enzymes.

  13. Dimeric [Mo₂S₁₂]²⁻ Cluster: A Molecular Analogue of MoS₂ Edges for Superior Hydrogen-Evolution Electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhongjie; Luo, Wenjia; Ma, Lu; Yu, Mingzhe; Ren, Xiaodi; He, Mingfu; Polen, Shan; Click, Kevin; Garrett, Benjamin R.; Lu, Jun; Amine, Khalil


    Proton reduction is one of the most fundamental and important reactions in nature. MoS2 edges have been identified as the active sites for hydrogen evolution reaction (HER) electrocatalysis. Designing molecular mimics of MoS2 edge sites is an attractive strategy to understand the underlying catalytic mechanism of different edge sites and improve their activities. Herein we report a dimeric molecular analogue [Mo₂S₁₂]²⁻, as the smallest unit possessing both the terminal and bridging disulfide ligands. Our electrochemical tests show that [Mo₂S₁₂]²⁻ is a superior heterogeneous HER catalyst under acidic conditions. Computations suggest that the bridging disulfide ligand of [Mo₂S₁₂]²⁻ exhibits a hydrogen adsorption free energy near zero (-0.05eV). This work helps shed light on the rational design of HER catalysts and biomimetics of hydrogen-evolving enzymes.

  14. Advances in aluminum pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Sudour, Michel; Maintier, Philippe [PPG Industries France, 3 Z.A.E. Les Dix Muids, B.P. 89, F-59583 Marly (France); Simpson, Mark [PPG Industries Inc., 1200 Piedmont Troy, Michigan 48083 (United States); Quaglia, Paolo [PPG Industries Italia, Via Garavelli 21, I-15028 Quattordio (Italy)


    As automotive manufacturers continue to look for ways to reduce vehicle weight, aluminum is finding more utility as a body panel component. The substitution of cold-rolled steel and zinc-coated substrates with aluminum has led to new challenges in vehicle pretreatment. As a result, changes to traditional pretreatment chemistries and operating practices are necessary in order to produce an acceptable coating on aluminum body panels. These changes result in increased sludging and other undesirable characteristics. In addition to the chemistry changes, there are also process-related problems to consider. Many existing automotive pretreatment lines simply were not designed to handle aluminum and its increased demands on filtration and circulation equipment. To retrofit such a system is capital intensive and in addition to requiring a significant amount of downtime, may not be totally effective. Thus, the complexities of pre-treating aluminum body panels have actually had a negative effect on efforts to introduce more aluminum into new vehicle design programs. Recent research into ways of reducing the negative effects has led to a new understanding of the nature of zinc phosphate bath -aluminum interactions. Many of the issues associated with the pretreatment of aluminum have been identified and can be mitigated with only minor changes to the zinc phosphate bath chemistry. The use of low levels of soluble Fe ions, together with free fluoride, has been shown to dramatically improve the efficiency of a zinc phosphate system processing aluminum. Appearance of zinc phosphate coatings, coating weights and sludge are all benefited by this chemistry change. (authors)

  15. The mechanism of nucleation of hydrogen blister in metals

    Institute of Scientific and Technical Information of China (English)

    REN XueChong; ZHOU QingJun; CHU WuYang; LI JinXu; SU YanJing; QIAO LiJie


    The nucleating, growing and cracking of hydrogen blister have been investigated experimentally and theoretically. The results show that atomic hydrogen induces superabundant vacancies in metals. The superabundant vacancies and hydrogen aggregate into a hydrogen-vacancy cluster (microcavity). The hydrogen atoms in the microcavity become hydrogen molecules which can stabilize the cluster. And the hydrogen blister nucleates. With the entry of vacancies and hydrogen atoms, the blister nucleus grows and the pressure in the cavity increases. When the stress induced by hydrogen pressure on the blister is up to the cohesive strength, cracks will initiate from the wall of the blister.

  16. Probing the Intact Cluster Catalysis Concept by Tetrahedral Clusters With Framework Chirality

    Institute of Scientific and Technical Information of China (English)

    G. Süss-Fink; L. Vieille-Petit


    @@ 1Results and Discussion In order to bring evidence for or against the hypothesis of catalytic hydrogenation by intact trinuclear arene ruthenium clusters containing an oxo cap, the substrate being hydrogenated inside the hydrophobic pocket spanned by the three arene ligands ("supramolecular cluster catalysis")[1], we synthesized cationic Ru3O clusters (See Fig. 1) with three different arene ligands (intrinsically chiral tetrahedra).

  17. Corrosion Inhibitors for Aluminum. (United States)

    Muller, Bodo


    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)

  18. Advances in aluminum anodizing (United States)

    Dale, K. H.


    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.


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


    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.)

  20. Is it homogeneous or heterogeneous catalysis derived from [RhCp*Cl2]2? In operando XAFS, kinetic, and crucial kinetic poisoning evidence for subnanometer Rh4 cluster-based benzene hydrogenation catalysis. (United States)

    Bayram, Ercan; Linehan, John C; Fulton, John L; Roberts, John A S; Szymczak, Nathaniel K; Smurthwaite, Tricia D; Özkar, Saim; Balasubramanian, Mahalingam; Finke, Richard G


    Determining the true, kinetically dominant catalytically active species, in the classic benzene hydrogenation system pioneered by Maitlis and co-workers 34 years ago starting with [RhCp*Cl(2)](2) (Cp* = [η(5)-C(5)(CH(3))(5)]), has proven to be one of the most challenging case studies in the quest to distinguish single-metal-based "homogeneous" from polymetallic, "heterogeneous" catalysis. The reason, this study will show, is the previous failure to use the proper combination of: (i) in operando spectroscopy to determine the dominant form(s) of the precatalyst's mass under catalysis (i.e., operating) conditions, and then crucially also (ii) the previous lack of the necessary kinetic studies, catalysis being a "wholly kinetic phenomenon" as J. Halpern long ago noted. An important contribution from this study will be to reveal the power of quantitiative kinetic poisoning experiments for distinguishing single-metal, or in the present case subnanometer Rh(4) cluster-based catalysis, from larger, polymetallic Rh(0)(n) nanoparticle catalysis, at least under favorable conditions. The combined in operando X-ray absorption fine structure (XAFS) spectroscopy and kinetic evidence provide a compelling case for Rh(4)-based, with average stoichiometry "Rh(4)Cp*(2.4)Cl(4)H(c)", benzene hydrogenation catalysis in 2-propanol with added Et(3)N and at 100 °C and 50 atm initial H(2) pressure. The results also reveal, however, that if even ca. 1.4% of the total soluble Rh(0)(n) had formed nanoparticles, then those Rh(0)(n) nanoparticles would have been able to account for all the observed benzene hydrogenation catalytic rate (using commercial, ca. 2 nm, polyethyleneglycol-dodecylether hydrosol stabilized Rh(0)(n) nanoparticles as a model system). The results--especially the poisoning methodology developed and employed--are of significant, broader interest since determining the nature of the true catalyst continues to be a central, often vexing issue in any and all catalytic reactions

  1. Aluminum-catalyzed silicon nanowires: Growth methods, properties, and applications (United States)

    Hainey, Mel F.; Redwing, Joan M.


    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.

  2. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal

    Energy Technology Data Exchange (ETDEWEB)

    Cau Dit Coumes, C., E-mail: [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Lambertin, D.; Lahalle, H.; Antonucci, P. [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/DEN/MAR/DTCD/SPDE, BP17171, 30207 Bagnols-sur-Cèze cedex (France); Cannes, C.; Delpech, S. [Institut de Physique Nucléaire, CNRS, Univ. Paris-Sud 11, 91406 Orsay Cedex (France)


    Highlights: • Binders capable of reducing the pore solution pH compared with Portland cements are reviewed. • The binders are then tested against aluminum corrosion. • Corrosion of aluminum metal is minimal with magnesium phosphate cement. • The H{sub 2} release can be reduced still further by adding LiNO{sub 3} to the mixing solution. • Electrochemical characterizations show that aluminum tends to a passive state. - Abstract: In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  3. Hydrogen diffusion in Al-Li alloys (United States)

    Anyalebechi, P. N.


    The diffusion coefficients of hydrogen in binary Al-Li alloys containing 1,2, and 3 wt pct Li have been determined from desorption curves of samples saturated with hydrogen at 473 to 873 K. Within this temperature range, the diffusivity of hydrogen in the binary Al-Li alloys investigated has an Arrhenius-type temperature dependence and follows the equation of the general form D = DT) where D 0exp(-Q/R is the diffusion coefficient (m2/s), D 0 is the preexponential or frequency factor (m2/s), R is the gas constant (J/K mol), Q is the activation energy (J/mol), and T is absolute temperature (K). The rate of diffusion of hydrogen in aluminum decreases with increase in lithium additions. This is provisionally attributed to the stronger local binding energy between hydrogen and lithium atoms in the aluminum metal lattice.

  4. Aluminum, parathyroid hormone, and osteomalacia

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  5. Defect recovery in aluminum irradiated with protons at 20 K

    DEFF Research Database (Denmark)

    Linderoth, S.; Rajainmäki, H.; Nieminen, R. M.


    Aluminum single crystals have been irradiated with 7.0-MeV protons at 20 K. The irradiation damage and its recovery are studied with positron-lifetime spectroscopy between 20 and 500 K. Stage-I recovery is observed at 40 K. At 240 K, loss of freely migrating vacancies is observed. Hydrogen...... in vacancies is found to stabilize the vacancies and prolong stage III to above 280 K, where the hydrogen bound to vacancies is released. Single and multiple occupancy of hydrogen atoms at monovacancies is put forward as the reason for the two recovery stages between 280 and 400 K. A binding energy of 0...

  6. Fabrication of aluminum foam from aluminum scrap Hamza

    Directory of Open Access Journals (Sweden)

    O. A. Osman1 ,


    Full Text Available In this study the optimum parameters affecting the preparation of aluminum foam from recycled aluminum were studied, these parameters are: temperature, CaCO3 to aluminum scrap wt. ratio as foaming agent, Al2O3 to aluminum scrap wt. ratio as thickening agent, and stirring time. The results show that, the optimum parameters are the temperature ranged from 800 to 850oC, CaCO3 to aluminum scrap wt. ratio was 5%, Al2O3 to aluminum scrap wt. ratio was 3% and stirring time was 45 second with stirring speed 1200 rpm. The produced foam apparent densities ranged from 0.40-0.60 g/cm3. The microstructure of aluminum foam was examined by using SEM, EDX and XRD, the results show that, the aluminum pores were uniformly distributed along the all matrices and the cell walls covered by thin oxide film.

  7. Cross section measurements of the processes occurring in the fragmentation of H{sub n}{sup +} (3 {<=} n {<=} 35) hydrogen clusters induced by high speed (60 keV/u) collisions on helium atoms; Mesure des sections efficaces des differents processus intervenant dans la fragmentation d`agregats d`hydrogene H{sub n}{sup +} (3 {<=} n {<=} 35) induite par collision a haute vitesse (60 keV/u) sur un atome d`helium

    Energy Technology Data Exchange (ETDEWEB)

    Louc, Sandrine [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France)


    Different processes involved in the fragmentation of ionised hydrogen clusters H{sub 3} + (H{sub 2}){sub (n-3)/2} (n = 5-35) have been studied in the same experiment: the fragmentation of the cluster is induced by the collision with an helium atom at high velocity ({approx_equal} c/100). The collision is realised in reversed kinematic - clusters are accelerated - which allows the detection of neutral and charged fragments. The different channels of fragmentation are identified by using coincidence techniques. For all the cluster sizes studied the capture cross sections of one electron of the target by the cluster is equal to the capture cross section of the H{sub 3}{sup +} ion. In the same way, the dissociation cross section of the H{sub 3}{sup +} core of the cluster does not depend on cluster size. These fragmentation processes are due to the interaction of H{sub 3}{sup +} core of the cluster and the helium atom without ionization of another component of the cluster. On the contrary, the cross sections of loss of one, two and three molecules by the cluster and the dissociation cross section of the cluster in all its molecular components depends strongly on the cluster size. This dependence is different from the one measured for the metastable decay of the cluster. Thus, the process of loss of molecules induced by a collision should correspond to a different dissociation mechanism. In regard of the singularities observed for the size dependence, the H{sub 9}{sup +}, H{sub 15}{sup +}, H{sub 19}{sup +} and H{sub 29}{sup +} clusters could be the `core` of the biggest clusters. These observation are in agreement with the size effects of smaller magnitude observed for the dissociation cross section (all the processes). The values of the cross section for the process of at least one ionization of the cluster indicate that about 80% of the fragmentation events result from this process. (author) 114 refs., 74 figs., 9 tabs.

  8. Electrically conductive anodized aluminum coatings (United States)

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


    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.

  9. China’s Aluminum Resources

    Institute of Scientific and Technical Information of China (English)


    <正> The aluminum industry makes one of the keyindustries in China’s industrial and agriculturalmodernization and features a high degree ofrelevance with all industries.Of all the 124existing industries in China,113 use aluminum,representing an industrial relevance rate of91%.The consumption of aluminum is also ofhigh relevance with China’s GDP.

  10. Hydrogen sensor (United States)

    Duan, Yixiang; Jia, Quanxi; Cao, Wenqing


    A hydrogen sensor for detecting/quantitating hydrogen and hydrogen isotopes includes a sampling line and a microplasma generator that excites hydrogen from a gas sample and produces light emission from excited hydrogen. A power supply provides power to the microplasma generator, and a spectrometer generates an emission spectrum from the light emission. A programmable computer is adapted for determining whether or not the gas sample includes hydrogen, and for quantitating the amount of hydrogen and/or hydrogen isotopes are present in the gas sample.

  11. Aluminum for Plasmonics (United States)


    in plasmon-enhanced light harvesting,14 photocatalysis ,511 surface- enhanced spectroscopies,1216 optics-based sensing,1722 nonlinear optics,2326...optical response of Al nanoparticles has appeared inconsistent relative to calculated spectra, even forwell-characterized geometries. Some studies have...model- ing their optical response. These results pro- vide a method for estimating the metallic purity of aluminum nanoparticles directly from their

  12. Purification of scrap aluminum foil and aluminum melt covering and protecting & atomic purification theory

    Institute of Scientific and Technical Information of China (English)

    倪红军; 孙宝德; 刘满平; 丁文江


    A new flux, JDN-I, including rare earth compounds, for purification of the scraps of 99.99% aluminum foil was introduced. The experimental results indicate that its function of degassing and deoxidizing is excellent. The hydrogen content of the scrap aluminum foil melt purified by JDN-I flux decreases greatly from 4.5 mL/kg to 1.2 mL/kg at 720 ℃. The tensile strength of the samples refined with JDN-I flux increases by 19.2% and the elongation increases by 38.3% in comparison with those without flux. The purification mechanism of JDN-I was discussed and a theory of covering, protecting & atomic purification was also put forward.


    Institute of Scientific and Technical Information of China (English)

    吴永恒; 蔡余峰; 曾华东; 阮文


    采用密度泛函理论(DFT)方法研究Li2Sim(m=2,4,6)链状团簇结构及其储氢性能。研究结果表明,氢分子在碱金属Li原子修饰的三种硅链结构中均发生吸附,并且每个Li原子都可以吸附多个氢分子,其中两个Li原子修饰Si2链的结构能够吸附氢分子的储氢质量分数达18.6 wt %,氢分子的平均吸附能为1.850 kcal/moL。结果表明,碱金属Li原子修饰的硅链在室温条件下可作为氢气的存储媒介。%The structures and the hydrogen storage properties of the alkali metallithium decorated the linear silicon atomic chainsclusters are investigated by using the density functional theory. The results show that the lithium atoms can decorate on the end of thesilicon atomic chain clusters but not suffer from clustering. Every Li atom can absorb up to several intact hydrogen molecules in the Li-decoratedsilicon atomic chainsLi2Sim (m=2, 4, 6) clusters. The calculated gravimetric density of hydrogen for Li-decorated the Si2chain cluster is up to 18.6 wt%, and the hydrogen average adsorption energy is 1.850 kcal.mol-1, which shows that the Li-decoratedsilicon atomic chainscan be used as hydrogen storage materials under the room temperature condition.

  14. Aluminum microstructures on anodic alumina for aluminum wiring boards. (United States)

    Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki


    The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide film of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices.

  15. 叠氮二乙基铝和镓多聚体结构和性质的密度泛函理论研究%Structure properties of Diethylmetallic Azides Clusters of Aluminum and Gallium by DFT

    Institute of Scientific and Technical Information of China (English)

    夏其英; 马登学; 杨吉民


    (Et2MN3)n(n=1 to 3, M=Al, Ga) clusters were studied by DFT/B3LYP method with SDD basis set. The dimer(Et2MN3)2 and trimer(Et2MN3)3(M=Al, Ga) are found to exhibit four membered M2N2 and six membered M3N3 ring structure, respectively.Compared with the monomer, the order of the bond length changes for the dimer(Et2MN3)2 and trimer(Et2MN3)3(M=Al, Ga) is as follows: Nα-M>Nα-Nβ>Nβ-Nγ≈M-C. Binding energies of the dimer (Et2AlN3)2 and trimer(Et2AlN3)3 clusters are 35.44 and 45.61 kJ·mol-1 lower than that of (Et2GaN3)2 and(Et2GaN3)3 clusters, respectively. Thermodynamic properties show that the dimer is the main composition of the(Et2MN3)n(n=1 to 3, M=Al, Ga) clusters at 298.2 K. The dimerization and trimerization are very favorable thermodynamically below 500 K.%采用DFT-B3LYP/SDD方法系统研究了(Et2MN3)n(n=1-3,M=Al, Ga) 体系.二聚体(Et2MN3)2和三聚体(Et2MN3)3(M=Al, Ga)分别拥有四元环M2N2和六元环M3N3结构.与单体相比,二聚体(Et2MN3)2和三聚体(Et2MN3)3(M=Al, Ga)的键长变化次序均为Nα-M>Nα-Nβ>Nβ-Nγ≈M-C.二聚体(Et2AlN3)2的结合能比(Et2GaN3)2低35.44 kJ·mol-1,而三聚体(Et2AlN3)3的结合能比(Et2GaN3)3低45.61 kJ·mol-1.热力学性质表明叠氮二乙基铝和镓体系在298.2 K温度下均以二聚体为主.在低于500 K的温度下,二聚化和三聚化反应在热力学上是有利的.

  16. Cluster headache (United States)

    Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... A cluster headache begins as a severe, sudden headache. The headache commonly strikes 2 to 3 hours after you fall ...

  17. Cluster Forests

    CERN Document Server

    Yan, Donghui; Jordan, Michael I


    Inspired by Random Forests (RF) in the context of classification, we propose a new clustering ensemble method---Cluster Forests (CF). Geometrically, CF randomly probes a high-dimensional data cloud to obtain "good local clusterings" and then aggregates via spectral clustering to obtain cluster assignments for the whole dataset. The search for good local clusterings is guided by a cluster quality measure $\\kappa$. CF progressively improves each local clustering in a fashion that resembles the tree growth in RF. Empirical studies on several real-world datasets under two different performance metrics show that CF compares favorably to its competitors. Theoretical analysis shows that the $\\kappa$ criterion is shown to grow each local clustering in a desirable way---it is "noise-resistant." A closed-form expression is obtained for the mis-clustering rate of spectral clustering under a perturbation model, which yields new insights into some aspects of spectral clustering.

  18. Aluminum Carbothermic Technology

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Marshall J.


    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

  19. Star Clusters


    Gieles, M.


    Star clusters are observed in almost every galaxy. In this thesis we address several fundamental problems concerning the formation, evolution and disruption of star clusters. From observations of (young) star clusters in the interacting galaxy M51, we found that clusters are formed in complexes of stars and star clusters. These complexes share similar properties with giant molecular clouds, from which they are formed. Many (70%) of the young clusters will not survive the fist 10 Myr, due to t...

  20. Laser assisted foaming of aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Kathuria, Y.P. [Laser X Co. Ltd., Aichi (Japan)


    Recently aluminum foams have evoked considerable interest as an alternative material owing to their wide range of applications ranging from microelectronics, through automobiles to aerospace industries. The manufacturing techniques and characterization methods for aluminum foams require further development to achieve effective and economical use of this material. In this communication the authors demonstrate the feasibility of unidirectional and localized expansion of the aluminum foam using the Nd-YAG/CO{sub 2} laser and powder metallurgy. (orig.)

  1. Hybrid Aluminum Composite Materials Based on Carbon Nanostructures

    Directory of Open Access Journals (Sweden)

    Tatiana S. Koltsova


    Full Text Available We investigated formation of carbon nanofibers grown by chemical deposition (CVD method using an acetylene-hydrogen mixture on the surface of micron-sized aluminum powder particles. To obtain uniform distribution of the carbon nanostructures on the particles we deposited nickel catalyst on the surface by spraying from the aqueous solution of nickel nitrate. It was found that increasing the time of the synthesis lowers the rate of growth of carbon nanostructures due to the deactivation of the catalyst. The Raman spectroscopy measurements confirm the presence of disordered carbon corresponding to CNFs in the specimen. X-ray photoelectron spectroscopy showed the presence of aluminum carbide in the hot pressed samples. An aluminum composite material prepared using 1 wt.% CNFs obtained by uniaxial cold pressing and sintering showed 30% increase in the hardness compared to pure aluminum, whereas the composites prepared by hot pressing showed 80% increase in the hardness. Composite materials have satisfactory ductility. Thus, the aluminum based material reinforced with carbon nanostructures should be appropriate for creating high-strength and light compacts for aerospace and automotive applications and power engineering.DOI:

  2. Aluminum and Other Coatings for the Passivation of Tritium Storage Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Korinko, P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    Using a highly sensitive residual gas analyzer, the off gassing of hydrogen, water, and hydrocarbons from surface treated storage vessels containing deuterium was measured. The experimental storage vessels were compared to a low off-gassing, electro-polished 304L canister. Alternative vessels were made out of aluminum, or were coatings on 304L steel. Coatings included powder pack aluminide, electro-plated aluminum, powder pack chromide, dense electro-plated chromium, copper plated, and copper plated with 25 and 50 percent nano-diamond. Vessels were loaded with low pressure deuterium to observe exchange with protium or hydrogen as observed with formation of HD and HDO. Off gas of D2O or possible CD4 was observed at mass 20. The main off gas in all of the studies was H2. The studies indicated that coatings required significant post coating treatment to reduce off gas and enhance the permeation barrier from gases likely added during the coating process. Dense packed aluminum coatings needed heating to drive off water. Electro-plated aluminum, chromium and copper coatings appeared to trap hydrogen from the plating process. Nano-diamond appeared to enhance the exchange rate with hydrogen off gas and its coating process trapped significant amounts of hydrogen. Aluminum caused more protium exchange than chromium treated surfaces. Aluminum coatings released more water but pure aluminum vessels released small amounts of hydrogen, little water, and generally performed well. Chromium coating had residual hydrogen that was difficult to totally outgas but otherwise gave low residuals for water and hydrocarbons. Our studies indicated that simple coating of as received 304L metal will not adequately block hydrogen. The base vessel needs to be carefully out gassed before applying a coating and the coating process will likely add additional hydrogen that must be removed. Initial simple bake out and leak checks up to 350° C for a few hours was found to be inadequate. All of the

  3. Electrodeposition of aluminum and aluminum-magnesium alloys at room temperature

    Institute of Scientific and Technical Information of China (English)

    阚洪敏; 祝跚珊; 张宁; 王晓阳


    Electrodeposition of aluminum from benzene-tetrahydrofuran−AlCl3−LiAlH4 was studied at room temperature. Galvanostatic electrolysis was used to investigate the effect of various parameters on deposit morphology and crystal size, including current density, temperature, molar ratio of benzene/tetrahydrofuran and stirring speed. The deposit microstructure was adjusted by changing the parameters, and the optimum operating conditions were determined. Dense, bright and adherent aluminum coatings were obtained over a wide range of current densities (10−25 mA/cm2), molar ratio of benzene and tetrahydrofuran (4:1 to 7:8) and stirring speeds (200−500 r/min). Smaller grain sizes and well-adhered deposits were obtained at lower temperatures. Aluminum-magnesium alloys could potentially be used as hydrogen storage materials. A novel method for Al−Mg deposition was proposed by using pure Mg anodes in the organic solvents system benzene-tetrahydrofuran−AlCl3−LiAlH4. XRD shows that the aluminum−magnesium alloys are mainly Al3Mg2 and Al12Mg17.

  4. Oxidative addition of the C-I bond on aluminum nanoclusters (United States)

    Sengupta, Turbasu; Das, Susanta; Pal, Sourav


    Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly sensitive to the geometrical shapes and electronic structures of the clusters rather than their size, imposing the fact that comprehensive studies on aluminum clusters can be beneficial for nanoscience and nanotechnology. To understand the possible reaction mechanism in detail, the reaction pathway is investigated with the ab initio Born Oppenheimer Molecular Dynamics (BOMD) simulation and the Natural Bond Orbital (NBO) analysis. In short, our theoretical study highlights the thermodynamic and kinetic details of C-I bond dissociation on aluminum clusters for future endeavors in cluster chemistry.Energetics and the in-depth reaction mechanism of the oxidative addition step of the cross-coupling reaction are studied in the framework of density functional theory (DFT) on aluminum nanoclusters. Aluminum metal in its bulk state is totally inactive towards carbon-halogen bond dissociation but selected Al nanoclusters (size ranging from 3 to 20 atoms) have shown a significantly lower activation barrier towards the oxidative addition reaction. The calculated energy barriers are lower than the gold clusters and within a comparable range with the conventional and most versatile Pd catalyst. Further investigations reveal that the activation energies and other reaction parameters are highly

  5. Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)



    This 2-page fact sheet provides a brief introduction to hydrogen production technologies. Intended for a non-technical audience, it explains how different resources and processes can be used to produce hydrogen. It includes an overview of research goals as well as “quick facts” about hydrogen energy resources and production technologies.

  6. Hydrogen storage

    NARCIS (Netherlands)

    Peters, C.J.; Sloan, E.D.


    The invention relates to the storage of hydrogen. The invention relates especially to storing hydrogen in a clathrate hydrate. The clathrate hydrate according to the present invention originates from a composition, which comprises water and hydrogen, as well as a promotor compound. The promotor comp

  7. Hydrogenation-induced microstructure changes in titanium

    Energy Technology Data Exchange (ETDEWEB)

    Laptev, R., E-mail:; Lider, A., E-mail:; Bordulev, Yu., E-mail:; Kudiiarov, V., E-mail:; Garanin, G., E-mail:


    Highlights: • Hydrogen induced microstructure changes in Ti studied by PL and DB spectroscopies. • Vacancies and vacancy clusters formed at concentration from 1.31 to 2.27 at.%. • Cluster-hydrogen and vacancy-hydrogen complexes formed at concentration up to 32 at.%. - Abstract: Microstructure changes of commercially pure titanium in a wide range of hydrogen concentrations from 0.8 at.% to 32.0 at.% were studied by means of positron lifetime spectroscopy and Doppler broadening spectroscopy. We have obtained new experimental data on the evolution of positron annihilation parameters τ{sub f}, τ{sub d} and their corresponding intensities I{sub f}, I{sub d,} as well as relative changes of parameters S/S{sub 0} and W/W{sub 0} depending on the hydrogen concentration in commercially pure titanium after gas-phase hydrogenation at 873 K. Results suggest that the hydrogenation of Ti samples up to concentrations of 1.31–2.27 at.% and subsequent cooling to a room temperature leads to the formation of vacancies and vacancy clusters. Further increase of the hydrogen concentration up to 32.0 at.% leads to the interaction of hydrogen with these defects and the formation of “cluster-hydrogen” and “vacancy-hydrogen” complexes.

  8. Neurofibrillary pathology and aluminum in Alzheimer's disease


    Shin, R. W.; Lee, V.M.Y.; Trojanowski, J.Q.


    Since the first reports of aluminum-induced neurofibrillary degeneration in experimental animals, extensive studies have been performed to clarify the role played by aluminum in the pathogenesis of Alzheimer's disease (AD). Additional evidence implicating aluminum in AD includes elevated levels of aluminum in the AD brain, epidemiological data linking aluminum exposure to AD, and interactions between aluminum and protein components in the pathological lesions o...

  9. The OLYMPUS internal hydrogen target

    Energy Technology Data Exchange (ETDEWEB)

    Bernauer, J.C., E-mail: [Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139 (United States); Carassiti, V.; Ciullo, G. [Istituto Nazionale di Fisica Nucleare and Università, 44100 Ferrara (Italy); Henderson, B.S. [Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139 (United States); Ihloff, E.; Kelsey, J. [Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139 (United States); MIT-Bates Linear Accelerator Center, Middleton, MA 01949 (United States); Lenisa, P. [Istituto Nazionale di Fisica Nucleare and Università, 44100 Ferrara (Italy); Milner, R. [Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139 (United States); MIT-Bates Linear Accelerator Center, Middleton, MA 01949 (United States); Schmidt, A. [Massachusetts Institute of Technology, Laboratory for Nuclear Science, Cambridge, MA 02139 (United States); Statera, M. [Istituto Nazionale di Fisica Nucleare and Università, 44100 Ferrara (Italy)


    An internal hydrogen target system was developed for the OLYMPUS experiment at DESY, in Hamburg, Germany. The target consisted of a long, thin-walled, tubular cell within an aluminum scattering chamber. Hydrogen entered at the center of the cell and exited through the ends, where it was removed from the beamline by a multistage pumping system. A cryogenic coldhead cooled the target cell to counteract heating from the beam and increase the density of hydrogen in the target. A fixed collimator protected the cell from synchrotron radiation and the beam halo. A series of wakefield suppressors reduced heating from beam wakefields. The target system was installed within the DORIS storage ring and was successfully operated during the course of the OLYMPUS experiment in 2012. Information on the design, fabrication, and performance of the target system is reported.

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  11. Aluminum Nanoholes for Optical Biosensing

    Directory of Open Access Journals (Sweden)

    Carlos Angulo Barrios


    Full Text Available Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (biosensing 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 (biosensing. 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.

  12. Ballistic Evaluation of 2060 Aluminum (United States)


    experiments in Experimental Facilities (EFs) 108 and 106, as well as John Hogan of ARL/AMB, Hugh Walter of Bowhead Science and Technology, and David aluminum (Al)-based monocoque armored-vehicle hulls such as those of the M2 Bradley Infantry Fighting Vehicles. Also in 2012 the Aluminum

  13. Heredity of Aluminum Melt by Electric Pulse Modification (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    QI Jin-gang; WANG Jian-zhong; DU Hui-ling; CAO Li-yun


    Heredity of high pure aluminum melts under different pulse electric field was investigated by means of repetitious remelt experiment. The results indicate that the genetic coefficient by measurement of grain size of cast structure has a close relation with pulse voltage. Moreover, the hereditary law accords with the function of In=1+e-αn+β. The stability of genetic carrier (cluster) comprises in the competition between repetitious cooling and heating impulse and the effect of electric pulse modification.

  14. Wettability of Aluminum on Alumina (United States)

    Bao, Sarina; Tang, Kai; Kvithyld, Anne; Tangstad, Merete; Engh, Thorvald Abel


    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.

  15. Feasibility Study and Demonstration of an Aluminum and Ice Solid Propellant

    Directory of Open Access Journals (Sweden)

    Timothee L. Pourpoint


    Full Text Available Aluminum-water reactions have been proposed and studied for several decades for underwater propulsion systems and applications requiring hydrogen generation. Aluminum and water have also been proposed as a frozen propellant, and there have been proposals for other refrigerated propellants that could be mixed, frozen in situ, and used as solid propellants. However, little work has been done to determine the feasibility of these concepts. With the recent availability of nanoscale aluminum, a simple binary formulation with water is now feasible. Nanosized aluminum has a lower ignition temperature than micron-sized aluminum particles, partly due to its high surface area, and burning times are much faster than micron aluminum. Frozen nanoscale aluminum and water mixtures are stable, as well as insensitive to electrostatic discharge, impact, and shock. Here we report a study of the feasibility of an nAl-ice propellant in small-scale rocket experiments. The focus here is not to develop an optimized propellant; however improved formulations are possible. Several static motor experiments have been conducted, including using a flight-weight casing. The flight weight casing was used in the first sounding rocket test of an aluminum-ice propellant, establishing a proof of concept for simple propellant mixtures making use of nanoscale particles.

  16. Electrocatalytic studies of osmium-ruthenium carbonyl cluster compounds for their application as methanol-tolerant cathodes for oxygen reduction reaction and carbon monoxide-tolerant anodes for hydrogen oxidation reaction

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Arco, E.; Uribe-Godinez, J.; Castellanos, R.H. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Escobedo (Mexico); Altamirano-Gutierrez, A.; Jimenez-Sandoval, O. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Querataro (Mexico)


    This paper provided details of an electrokinetic study of novel electrocatalytic materials capable of performing both the oxygen reduction reaction (ORR) and the hydrogen oxidation reaction (HOR). Osmium-ruthenium carbonyl cluster compounds (Os{sub x}Ru{sub 3}(CO){sub n}) were synthesized by chemical condensation in non-polar organic solvents at different boiling points and refluxing temperatures. Three different non-polar organic solvents were used: (1) n-nonane; o-xylene; and 1,2-dichlorobenzene. The electrocatalysts were characterized by Fourier Transform Infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). A rotating disk electrode technique was used to analyze the materials. Results of the analysis showed that the materials performed ORR in both the presence and absence of carbon monoxide (CO), and that electrocatalysts were not poisoned by the presence of CO. Cyclic voltamperometry for the disk electrodes showed that the electrochemical behaviour of the compounds in the acid electrolyte was similar in the presence or absence of methanol. The Tafel slope, exchange current density and the transfer coefficient were also investigated. The electrokinetic parameters for the ORR indicated that the materials with the highest electrocatalytic activity were synthesized in 1,2-dichlorobenzene. Electrocatalytic activity during HOR were prepared in n-nonane. It was concluded that the new materials are good candidates for use as both a cathode and an anode in proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). 7 refs., 2 tabs., 7 figs.

  17. Biomimetic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Krassen, Henning


    Hydrogenases catalyze the reduction of protons to molecular hydrogen with outstanding efficiency. An electrode surface which is covered with active hydrogenase molecules becomes a promising alternative to platinum for electrochemical hydrogen production. To immobilize the hydrogenase on the electrode, the gold surface was modified by heterobifunctional molecules. A thiol headgroup on one side allowed the binding to the gold surface and the formation of a self-assembled monolayer. The other side of the molecules provided a surface with a high affinity for the hydrogenase CrHydA1 from Chlamydomonas reinhardtii. With methylviologen as a soluble energy carrier, electrons were transferred from carboxy-terminated electrodes to CrHydA1 and conducted to the active site (H-cluster), where they reduce protons to molecular hydrogen. A combined approach of surface-enhanced infrared absorption spectroscopy, gas chromatography, and surface plasmon resonance allowed quantifying the hydrogen production on a molecular level. Hydrogen was produced with a rate of 85 mol H{sub 2} min{sup -1} mol{sup -1}. On a 1'- benzyl-4,4'-bipyridinum (BBP)-terminated surface, the electrons were mediated by the monolayer and no soluble electron carrier was necessary to achieve a comparable hydrogen production rate (approximately 50% of the former system). The hydrogen evolution potential was determined to be -335 mV for the BBP-bound hydrogenase and -290 mV for the hydrogenase which was immobilized on a carboxy-terminated mercaptopropionic acid SAM. Therefore, both systems significantly reduce the hydrogen production overpotential and allow electrochemical hydrogen production at an energy level which is close to the commercially applied platinum electrodes (hydrogen evolution potential of -270 mV). In order to couple hydrogen production and photosynthesis, photosystem I (PS1) from Synechocystis PCC 6803 and membrane-bound hydrogenase (MBH) from Ralstonia eutropha were bound to each other

  18. Hualu Aluminum Will Construct Large Coal-Power-Aluminum Aluminum Processing Industrial Chain

    Institute of Scientific and Technical Information of China (English)


    The reporter learned from relevant departments of Baiyin City that in order to further push forward industrial upgrading,fulfill expansion and consolidation of the enterprise,Gansu Hualu Aluminum Co.,Ltd(Hualu Aluminum)will implement Out-Of-City-Into-Park project,

  19. Validity of the Aluminum Equivalent Approximation in Space Radiation Shielding (United States)

    Badavi, Francis F.; Adams, Daniel O.; Wilson, John W.


    imagine the progression to greater thickness, the current range will be sufficient to evaluate the qualitative usefulness of the aluminum equivalent approximation. Upon establishing the inaccuracies of the aluminum equivalent approximation through numerical simulations of the GCR radiation field attenuation for PE and aluminum equivalent PE spherical shells, we Anther present results for a limited set of commercially available, hydrogen rich, multifunctional polymeric constituents to assess the effect of the aluminum equivalent approximation on their radiation attenuation response as compared to the generic PE.

  20. Spray Rolling Aluminum Strip

    Energy Technology Data Exchange (ETDEWEB)

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.


    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.

  1. Hydrogen Spectrum (United States)

    Murdin, P.


    The series of absorption or emission lines that are characteristic of the hydrogen atom. According to the Bohr theory of the hydrogen atom, devised by Danish physicist Neils Bohr (1885-1962) in 1913, the hydrogen atom can be envisaged as consisting of a central nucleus (a proton) around which a single electron revolves. The electron is located in one of a number of possible permitted orbits, each...

  2. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys (United States)

    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. Selection of a mineral binder with potentialities for the stabilization/solidification of aluminum metal (United States)

    Cau Dit Coumes, C.; Lambertin, D.; Lahalle, H.; Antonucci, P.; Cannes, C.; Delpech, S.


    In a strongly alkaline medium, such as that encountered in conventional cementitious materials based on Portland cement, aluminum metal is corroded, with continued production of hydrogen. In order to develop a mineral matrix having enhanced compatibility with aluminum, a literature review was first undertaken to identify binders capable of reducing the pore solution pH compared with Portland cement. An experimental study was then carried out to measure the hydrogen production resulting from corrosion of aluminum metal rods encapsulated in the different selected cement pastes. The best results were achieved with magnesium phosphate cement, which released very little hydrogen over the duration of the study. This production could be reduced still further by adding a corrosion inhibitor (lithium nitrate) to the mixing solution. Open circuit potential measurement and Electrochemical Impedance Spectroscopy of aluminum electrode encapsulated in two pastes based on Portland cement and magnesium phosphate cement showed different redox behaviors. In the Portland cement paste, the electrochemical data confirmed the corrosion of aluminum whereas this latter tended to a passive state in the magnesium phosphate binder.

  4. Meaningful Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.


    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  5. Epitaxial clusters in single crystal hosts

    Energy Technology Data Exchange (ETDEWEB)

    Bohr, J. (Risoe National Lab., Roskilde (Denmark). Dept. of Solid State Physics)


    It is a general phenomenon for single crystal hosts that insoluble materials precipitate in the form of epitaxially aligned clusters. Such precipitates (or inclusions) are therefore coherently aligned and offer a unique model system for X-ray diffraction studies. In this paper, the general phenomenon of epitaxial clusters is discussed, and specific X-ray experiments on krypton as well as lead clusters in aluminum are presented. A hypothesis for the origin of epitaxial alignment is described and interfacial roughening is discussed. Also discussed is superheating and supercooling at the melting transition. (orig.).

  6. Preparation of three-dimensional shaped aluminum alloy foam by two-step foaming

    Energy Technology Data Exchange (ETDEWEB)

    Shang, J.T. [Key laboratory of MEMS of Ministry of Education, Southeast University, Nanjing 210096 (China)], E-mail:; Xuming, Chu; Deping, He [School of Materials Science and Engineering, Southeast University, Nanjing 210096 (China)


    A novel method, named two-step foaming, was investigated to prepare three-dimensional shaped aluminum alloy foam used in car industry, spaceflight, packaging and related areas. Calculations of thermal decomposition kinetics of titanium hydride showed that there is a considerable amount of hydrogen releasing when the titanium hydride is heated at a relatively high temperature after heated at a lower temperature. The hydrogen mass to sustain aluminum alloy foam, having a high porosity, was also estimated by calculations. Calculations indicated that as-received titanium hydride without any pre-treatment can be used as foaming agents in two-step foaming. The processes of two-step foaming, including preparing precursors and baking, were also studied by experiments. Results showed that, low titanium hydride dispersion temperature, long titanium hydride dispersion time and low precursors porosity are beneficial to prepare three-dimensional shaped aluminum alloy foams with uniform pores.

  7. Weighted Clustering

    DEFF Research Database (Denmark)

    Ackerman, Margareta; Ben-David, Shai; Branzei, Simina


    We investigate a natural generalization of the classical clustering problem, considering clustering tasks in which different instances may have different weights.We conduct the first extensive theoretical analysis on the influence of weighted data on standard clustering algorithms in both...... the partitional and hierarchical settings, characterizing the conditions under which algorithms react to weights. Extending a recent framework for clustering algorithm selection, we propose intuitive properties that would allow users to choose between clustering algorithms in the weighted setting and classify...... algorithms accordingly....

  8. Hydrogen Bibliography

    Energy Technology Data Exchange (ETDEWEB)


    The Hydrogen Bibliography is a compilation of research reports that are the result of research funded over the last fifteen years. In addition, other documents have been added. All cited reports are contained in the National Renewable Energy Laboratory (NREL) Hydrogen Program Library.

  9. Hydrogen carriers (United States)

    He, Teng; Pachfule, Pradip; Wu, Hui; Xu, Qiang; Chen, Ping


    Hydrogen has the potential to be a major energy vector in a renewable and sustainable future energy mix. The efficient production, storage and delivery of hydrogen are key technical issues that require improvement before its potential can be realized. In this Review, we focus on recent advances in materials development for on-board hydrogen storage. We highlight the strategic design and optimization of hydrides of light-weight elements (for example, boron, nitrogen and carbon) and physisorbents (for example, metal-organic and covalent organic frameworks). Furthermore, hydrogen carriers (for example, NH3, CH3OH-H2O and cycloalkanes) for large-scale distribution and for on-site hydrogen generation are discussed with an emphasis on dehydrogenation catalysts.

  10. Cluster Lenses

    CERN Document Server

    Kneib, Jean-Paul; 10.1007/s00159-011-0047-3


    Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple-images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es) - understanding cluster mass distributions and issues pertaining...

  11. Use of Hydrogen Peroxide to Disinfect Hydroponic Plant Growth Systems (United States)

    Barta, Daniel J.; Henderson, Keith


    Hydrogen peroxide was studied as an alternative to conventional bleach and rinsing methods to disinfect hydroponic plant growth systems. A concentration of 0.5% hydrogen peroxide was found to be effective. Residual hydrogen peroxide can be removed from the system by repeated rinsing or by flowing the solution through a platinum on aluminum catalyst. Microbial populations were reduced to near zero immediately after treatment but returned to pre-disinfection levels 2 days after treatment. Treating nutrient solution with hydrogen peroxide and planting directly into trays being watered with the nutrient solution without replenishment, was found to be detrimental to lettuce germination and growth.

  12. Effect of Tritium on Cracking Threshold in 7075 Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Morgan, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    The effect of long-term exposure to tritium gas on the cracking threshold (KTH) of 7075 Aluminum Alloy was investigated. The alloy is the material of construction for a cell used to contain tritium in an accelerator at Jefferson Laboratory designed for inelastic scattering experiments on nucleons. The primary safety concerns for the Jefferson Laboratory tritium cell is a tritium leak due to mechanical failure of windows from hydrogen isotope embrittlement, radiation damage, or loss of target integrity from accidental excessive beam heating due to failure of the raster or grossly mis-steered beam. Experiments were conducted to investigate the potential for embrittlement of the 7075 Aluminum alloy from tritium gas.

  13. Invisible Display in Aluminum

    DEFF Research Database (Denmark)

    Prichystal, Jan Phuklin; Hansen, Hans Nørgaard; Bladt, Henrik Henriksen


    Bang & Olufsen a/s has been working with ideas for invisible integration of displays in metal surfaces. Invisible integration of information displays traditionally has been possible by placing displays behind transparent or semitransparent materials such as plastic or glass. The wish for an integ...... be obtained by shining light from the backside of the workpiece. When there is no light from the backside, the front surface seems totally untouched. This was achieved by laser ablation with ultra-short pulses.......Bang & Olufsen a/s has been working with ideas for invisible integration of displays in metal surfaces. Invisible integration of information displays traditionally has been possible by placing displays behind transparent or semitransparent materials such as plastic or glass. The wish...... for an integrated display in a metal surface is often ruled by design and functionality of a product. The integration of displays in metal surfaces requires metal removal in order to clear the area of the display to some extent. The idea behind an invisible display in Aluminum concerns the processing of a metal...

  14. Anodized aluminum on LDEF (United States)

    Golden, Johnny L.


    A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

  15. Gas evolution behavior of aluminum in mortar

    Energy Technology Data Exchange (ETDEWEB)

    Hashizume, Shuji; Matsumoto, Junko; Banba, Tsunetaka [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    As a part of study of leaching behavior for solidified dry low level radioactive waste, gas evolution behavior of aluminum in mortar was investigated, and a plan of our research was proposed. The effect of pH on corrosion rate of aluminum, corrosion product, time dependency of corrosion rate of aluminum in mortar, change of corrosion mechanism, the effects of Na, Ca and Cl ions on corrosion rate of aluminum in mortar and corrosion behavior of aluminum when aluminum was used as sacrificed anode in reinforced concrete were previously clarified. Study of the effects of environmental factors such as pH, kind of ions and temperature on gas evolution behavior of aluminum and the effect of aluminum/carbon steel surface ratio no gas evolution behavior of aluminum were planed. (author). 75 refs.

  16. Low-aluminum content iron-aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Goodwin, G.M.; Alexander, D.J. [and others


    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.

  17. Data Clustering (United States)

    Wagstaff, Kiri L.


    On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained

  18. Ultrasonic degradation of Rhodamine B in the presence of hydrogen peroxide and some metal oxide. (United States)

    Mehrdad, Abbas; Hashemzadeh, Robab


    In this research, degradation of Rodamine B in the presence of (hydrogen peroxide), (hydrogen peroxide+ultrasound), (hydrogen peroxide+aluminum oxide), (hydrogen peroxide+aluminum oxide+ultrasound with different ultrasound power), (hydrogen peroxide+iron oxide) and (hydrogen peroxide+iron oxide+ultrasound with different ultrasound power) were investigated at 25 degrees C. The apparent rate constants for the examined systems were calculated by pseudo-first-order kinetics. The results indicate that the rate of degradation was accelerated by ultrasound. The rate of degradation was increased by increasing power ultrasound. The efficiency of the (hydrogen peroxide+iron oxide+ultrasound) system for degradation of Rodamine B was higher than the others examined.

  19. Cluster Chemistry

    Institute of Scientific and Technical Information of China (English)


    @@ Cansisting of eight scientists from the State Key Laboratory of Physical Chemistry of Solid Surfaces and Xiamen University, this creative research group is devoted to the research of cluster chemistry and creation of nanomaterials.After three-year hard work, the group scored a series of encouraging progresses in synthesis of clusters with special structures, including novel fullerenes, fullerene-like metal cluster compounds as well as other related nanomaterials, and their properties study.

  20. Scaleable Clean Aluminum Melting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Das, S.K. (Secat, Inc.)


    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.

  1. Quantum molecular dynamics simulations of hydrogen production and solar cells (United States)

    Mou, Weiwei

    The global energy crisis presents two major challenges for scientists around the world: Producing cleaner energy which is sustainable for the environment; And improving the efficiency of energy production as well as consumption. It is crucial and yet elusive to understand the atomistic mechanisms and electronic properties, which are needed in order to tackle those challenges. Quantum molecular dynamics simulations and nonadiabatic quantum molecular dynamics are two of the dominant methods used to address the atomistic and electronic properties in various energy studies. This dissertation is an ensemble of three studies in energy research: (1) Hydrogen production from the reaction of aluminum clusters with water to provide a renewable energy cycle; (2) The photo-excited charge transfer and recombination at a quaterthiophene/zinc oxide interface to improve the power conversion efficiency of hybrid poly(3-hexylthiophene) (P3HT) /ZnO solar cells; and (3) the charge transfer at a rubrene/C60 interface to understand why phenyl groups in rubrene improve the performance of rubrene/C60 solar cells.

  2. Clustered regression with unknown clusters

    CERN Document Server

    Barman, Kishor


    We consider a collection of prediction experiments, which are clustered in the sense that groups of experiments ex- hibit similar relationship between the predictor and response variables. The experiment clusters as well as the regres- sion relationships are unknown. The regression relation- ships define the experiment clusters, and in general, the predictor and response variables may not exhibit any clus- tering. We call this prediction problem clustered regres- sion with unknown clusters (CRUC) and in this paper we focus on linear regression. We study and compare several methods for CRUC, demonstrate their applicability to the Yahoo Learning-to-rank Challenge (YLRC) dataset, and in- vestigate an associated mathematical model. CRUC is at the crossroads of many prior works and we study several prediction algorithms with diverse origins: an adaptation of the expectation-maximization algorithm, an approach in- spired by K-means clustering, the singular value threshold- ing approach to matrix rank minimization u...

  3. Subspace clustering through attribute clustering

    Institute of Scientific and Technical Information of China (English)

    Kun NIU; Shubo ZHANG; Junliang CHEN


    Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.

  4. Decreasing residual aluminum level in drinking water

    Institute of Scientific and Technical Information of China (English)

    王志红; 崔福义


    The relativity of coagulant dosage, residual turbidity, temperature, pH etc. with residual aluminum concentration were investigated, and several important conclusions were achieved. Firstly, dosage of alum-coagulant or PAC1 influences residual aluminum concentration greatly. There is an optimal-dosage-to-aluminum, a bit less than the optimal-dosage-to-turbidity. Secondly, it proposes that decreasing residual aluminum concentration can be theoretically divided into two methods, either decreasing (even removing) the concentration of particulate aluminum component, or decreasing dissolved aluminum. In these tests there is an optimal value of residual turbidity of postprecipitation at 7.0 NTU. Thirdly, residual aluminum level will increase while water temperature goes higher. At the last, optimal pH value corresponds a minimum dissolved aluminum at a given turbidity. Data shows the optimal pH value decreases with water temperature's increasing.

  5. 21 CFR 172.310 - Aluminum nicotinate. (United States)


    ... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be safely... additive, expressed as niacin, shall appear on the label of the food additive container or on that of...

  6. Environmental Control over the Primary Aluminum Industry

    Institute of Scientific and Technical Information of China (English)


    <正> To strengthen environmental control over theprimary aluminum industry,the State Environ-mental Protection Administration of China hasrecently issued a notice addressing the follow-ing points:Strengthening environmental control over theexisting primary aluminum companies


    Directory of Open Access Journals (Sweden)

    Mohammed Ali Hajeeh


    Full Text Available Minimizing the amount of scrap generated in an aluminum extrusion process. An optimizing model is constructed in order to select the best cutting patterns of aluminum logs and billets of various sizes and shapes. The model applied to real data obtained from an existing extrusion factory in Kuwait. Results from using the suggested model provided substantial reductions in the amount of scrap generated. Using sound mathematical approaches contribute significantly in reducing waste and savings when compared to the existing non scientific techniques.

  8. Electrochemical Behavior of Aluminum in Nitric Acid

    Institute of Scientific and Technical Information of China (English)

    CHEN; Hui; ZHU; Li-yang; LIN; Ru-shan; TAN; Hong-bin; HE; Hui


    Aluminum is one of cladding materials for nuclear fuel,it is important to investigate the electrolytic dissolution of aluminum in nitric acid.The electrochemical impedance spectroscopy,polarization curve and cyclic voltammetry cure of anodic aluminum electrode in nitric acid under various conditions were collected(Fig.1).It turns out,under steady state,the thickness of the passivated film of aluminum

  9. Statistical theory for hydrogen bonding fluid system of AaDd type (Ⅱ): Properties of hydrogen bonding networks

    Institute of Scientific and Technical Information of China (English)

    WANG HaiJun; HONG XiaoZhong; GU Fang; BA XinWu


    Making use of the invariant property of the equilibrium size distribution of the hydrogen bonding clusters formed in hydrogen bonding system of AaDd type, the analytical expressions of the free energy in pregel and postgel regimes are obtained. Then the gel free energy and the scaling behavior of the number of hydrogen bonds in gel phase near the critical point are investigated to give the corresponding scaling exponents and scaling law. Meanwhile, some properties of intermolecular and intramolecular hydrogen bonds in the system, sol and gel phases are discussed. As a result, the explicit relationship between the number of intramolecular hydrogen bonds and hydrogen bonding degree is obtained.

  10. 76 FR 23490 - Aluminum tris (O (United States)


    ... AGENCY 40 CFR Part 180 Aluminum tris (O-ethylphosphonate), Butylate, Chlorethoxyfos, Clethodim, et al..., fosthiazate, propetamphos, and tebufenozide; the fungicide aluminum tris (O-ethylphosphonate); the herbicides.... Also, EPA is revoking the tolerances for aluminum tris (O-ethylphosphonate) on pineapple fodder...

  11. Guangxi Aluminum Giant Made Investment in Changfeng

    Institute of Scientific and Technical Information of China (English)


    <正>A aluminum processing and supporting project (450,000 tons) of Hefei Guangyin Aluminum Company kicked off in Xiatang Town of Changfeng County recently. It is a project jointly invested by Guangxi Investment Group and Guangxi Baise Guangyin Aluminum in Xiatang Town of Changfeng County.

  12. Hydrogen program overview

    Energy Technology Data Exchange (ETDEWEB)

    Gronich, S. [Dept. of Energy, Washington, DC (United States). Office of Utility Technologies


    This paper consists of viewgraphs which summarize the following: Hydrogen program structure; Goals for hydrogen production research; Goals for hydrogen storage and utilization research; Technology validation; DOE technology validation activities supporting hydrogen pathways; Near-term opportunities for hydrogen; Market for hydrogen; and List of solicitation awards. It is concluded that a full transition toward a hydrogen economy can begin in the next decade.

  13. Cryogenic hydrogen-induced air liquefaction technologies (United States)

    Escher, William J. D.


    Extensively utilizing a special advanced airbreathing propulsion archives database, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen-induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented. The resulting assessment report is summarized. Technical findings are presented relating the status of air liquefaction technology, both as a singular technical area, and also that of a cluster of collateral technical areas including: compact lightweight cryogenic heat exchangers; heat exchanger atmospheric constituents fouling alleviation; para/ortho hydrogen shift conversion catalysts; hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; hydrogen recycling using slush hydrogen as heat sink; liquid hydrogen/liquid air rocket-type combustion devices; air collection and enrichment systems (ACES); and technically related engine concepts.

  14. Proteomic Properties Reveal Phyloecological Clusters of Archaea (United States)

    Nikolic, Nela; Smole, Zlatko; Krisko, Anita


    In this study, we propose a novel way to describe the variety of environmental adaptations of Archaea. We have clustered 57 Archaea by using a non-redundant set of proteomic features, and verified that the clusters correspond to environmental adaptations to the archaeal habitats. The first cluster consists dominantly of hyperthermophiles and hyperthermoacidophilic aerobes. The second cluster joins together halophilic and extremely halophilic Archaea, while the third cluster contains mesophilic (mostly methanogenic) Archaea together with thermoacidophiles. The non-redundant subset of proteomic features was found to consist of five features: the ratio of charged residues to uncharged, average protein size, normalized frequency of beta-sheet, normalized frequency of extended structure and number of hydrogen bond donors. We propose this clustering to be termed phyloecological clustering. This approach could give additional insights into relationships among archaeal species that may be hidden by sole phylogenetic analysis. PMID:23133575

  15. Proteomic properties reveal phyloecological clusters of Archaea.

    Directory of Open Access Journals (Sweden)

    Nela Nikolic

    Full Text Available In this study, we propose a novel way to describe the variety of environmental adaptations of Archaea. We have clustered 57 Archaea by using a non-redundant set of proteomic features, and verified that the clusters correspond to environmental adaptations to the archaeal habitats. The first cluster consists dominantly of hyperthermophiles and hyperthermoacidophilic aerobes. The second cluster joins together halophilic and extremely halophilic Archaea, while the third cluster contains mesophilic (mostly methanogenic Archaea together with thermoacidophiles. The non-redundant subset of proteomic features was found to consist of five features: the ratio of charged residues to uncharged, average protein size, normalized frequency of beta-sheet, normalized frequency of extended structure and number of hydrogen bond donors. We propose this clustering to be termed phyloecological clustering. This approach could give additional insights into relationships among archaeal species that may be hidden by sole phylogenetic analysis.

  16. Cluster editing

    DEFF Research Database (Denmark)

    Böcker, S.; Baumbach, Jan


    . The problem has been the inspiration for numerous algorithms in bioinformatics, aiming at clustering entities such as genes, proteins, phenotypes, or patients. In this paper, we review exact and heuristic methods that have been proposed for the Cluster Editing problem, and also applications......The Cluster Editing problem asks to transform a graph into a disjoint union of cliques using a minimum number of edge modifications. Although the problem has been proven NP-complete several times, it has nevertheless attracted much research both from the theoretical and the applied side...

  17. Cluster analysis

    CERN Document Server

    Everitt, Brian S; Leese, Morven; Stahl, Daniel


    Cluster analysis comprises a range of methods for classifying multivariate data into subgroups. By organizing multivariate data into such subgroups, clustering can help reveal the characteristics of any structure or patterns present. These techniques have proven useful in a wide range of areas such as medicine, psychology, market research and bioinformatics.This fifth edition of the highly successful Cluster Analysis includes coverage of the latest developments in the field and a new chapter dealing with finite mixture models for structured data.Real life examples are used throughout to demons

  18. Weighted Clustering

    CERN Document Server

    Ackerman, Margareta; Branzei, Simina; Loker, David


    In this paper we investigate clustering in the weighted setting, in which every data point is assigned a real valued weight. We conduct a theoretical analysis on the influence of weighted data on standard clustering algorithms in each of the partitional and hierarchical settings, characterising the precise conditions under which such algorithms react to weights, and classifying clustering methods into three broad categories: weight-responsive, weight-considering, and weight-robust. Our analysis raises several interesting questions and can be directly mapped to the classical unweighted setting.

  19. High Strength Discontinuously Reinforced Aluminum For Rocket Applications (United States)

    Pandey, A. B.; Shah, S. R.; Shadoan, M.


    This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.

  20. Aluminum break-point contacts

    NARCIS (Netherlands)

    Heinemann, Martina; Groot, R.A. de


    Ab initio molecular dynamics is used to study the contribution of a single Al atom to an aluminum breakpoint contact during the final stages of breaking and the initial stages of the formation of such a contact. A hysteresis effect is found in excellent agreement with experiment and the form of the

  1. Evaluation of insulated pressure vessels for cryogenic hydrogen storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Garcia-Villazana, O; Martinez-Frias, J


    This paper presents an analytical and experimental evaluation of the applicability of insulated pressure vessels for hydrogen-fueled light-duty vehicles. Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen (LH?) or ambient-temperature compressed hydrogen (CH2). Insulated pressure vessels offer the advantages of liquid hydrogen tanks (low weight and volume), with reduced disadvantages (lower energy requirement for hydrogen liquefaction and reduced evaporative losses). The purpose of this work is to verify that commercially available aluminum-lined, fiber- wrapped vessels can be used for cryogenic hydrogen storage. The paper reports on previous and ongoing tests and analyses that have the purpose of improving the system design and assure its safety.

  2. Energetics of H$_2$ clusters from density functional and coupled cluster theories

    CERN Document Server

    Trail, J R; Needs, R J


    We use coupled-cluster quantum chemical methods to calculate the energetics of molecular clusters cut out of periodic molecular hydrogen structures that model observed phases of solid hydrogen. The hydrogen structures are obtained from Kohn-Sham density functional theory (DFT) calculations at pressures of 150, 250 and 350 GPa, which are within the pressure range in which phases II, III and IV are found to be stable. The calculated deviations in the DFT energies from the coupled-cluster data are reported for different functionals, and optimized functionals are generated which provide reduced errors. We give recommendations for semi-local and hybrid density functionals that are expected to accurately describe hydrogen at high pressures.

  3. Energetics of H2 clusters from density functional and coupled cluster theories (United States)

    Trail, J. R.; López Ríos, P.; Needs, R. J.


    We use coupled-cluster quantum chemical methods to calculate the energetics of molecular clusters cut out of periodic molecular hydrogen structures that model observed phases of solid hydrogen. The hydrogen structures are obtained from Kohn-Sham density functional theory (DFT) calculations at pressures of 150, 250, and 350 GPa, which are within the pressure range in which phases II, III, and IV are found to be stable. The calculated deviations in the DFT energies from the coupled-cluster data are reported for different functionals, and optimized functionals are generated which provide reduced errors. We give recommendations for semilocal and hybrid density functionals that are expected to provide an accurate description of hydrogen at high pressures.

  4. Ground state structures and properties of Si3H ( = 1–6) clusters

    Indian Academy of Sciences (India)

    D Balamurugan; R Prasad


    The ground state structures and properties of Si3H (1 ≤ ≤ 6) clusters have been calculated using Car–Parrinello molecular dynamics with simulated annealing and steepest descent optimization methods. We have studied cohesive energy per particle and first excited electronic level gap of the clusters as a function of hydrogenation. Hydrogenation is done till all dangling bonds of silicon are saturated. Our results show that over coordination of hydrogen is favoured in Si3H clusters and the geometry of Si3 cluster does not change due to hydrogenation. Cohesive energy per particle and first excited electronic level gap study of the clusters show that Si3H6 cluster is most stable and Si3H3 cluster is most unstable among the clusters considered here.

  5. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, aluminum 7075-T651, and titanium 6Al-4V (United States)

    Terrell, J.


    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 7075-T651 and titanium 6A1-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 6) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity). Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, a similar observation was not noted for titanium stressed specimens. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl); while they (both alloys) seem to resist stress corrosion cracking in methyl alcohol, ethyl alcohol, iso-propyl alcohol, and demineralized distilled water. Titanium 6A1-4V showed some evidence of susceptibility to SCC in methanol, while no such susceptibility was exhibited in ethanol, iso-propyl alcohol and demineralized distilled water.

  6. Radiolysis of water with aluminum oxide surfaces (United States)

    Reiff, Sarah C.; LaVerne, Jay A.


    Aluminum oxide, Al2O3, nanoparticles with water were irradiated with γ-rays and 5 MeV He ions followed by the determination of the production of molecular hydrogen, H2, and characterization of changes in the particle surface. Surface analysis techniques included: diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), nitrogen absorption with the Brunauer - Emmett - Teller (BET) methodology for surface area determination, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Production of H2 by γ-ray radiolysis was determined for samples with adsorbed water and for Al2O3 - water slurries. For Al2O3 samples with adsorbed water, the radiation chemical yield of H2 was measured as 80±20 molecules/100 eV (1 molecule/100 eV=1.04×10-7 mol/J). The yield of H2 was observed to decrease as the amount of water present in the Al2O3 - water slurries increased. Surface studies indicated that the α-phase Al2O3 samples changed phase following irradiation by He ions, and that the oxyhydroxide layer, present on the pristine sample, is removed by γ-ray and He ion irradiation.

  7. Study on Diffusion of Hydrogen in AB5 Non-Stoichiometric Hydrogen Absorbing Alloys

    Institute of Scientific and Technical Information of China (English)

    王志兴; 李新海; 陈启元; 彭文杰; 郭华军


    The diffusion coefficient of hydrogen atoms in the studied alloys was electroche mically measured by chronoamperometry when the metallic hydride microelectrodes were completely discharged. It is found that the diffusion coefficient of hydrogen atoms decreases when cobalt is substituted for a minority of nickel. On the contrary, the diffusion coefficient increases with the partial substitution of manganese or aluminum for nickel, which is related to the lattice constant and cell volumes of hydrogen absorbing alloys. The lattice constant c is obviously affected by the substitute elements greatly. The result shows that the expansion of cell volume resulted from the increase of value c causes the increase of diffusion coefficient which is especially obvious when the lattice constant is relatively low. However, this relationship is not clear if the lattice constant increases to some extent. It is suggested that this phenomenon is related to the interaction of hydrogen atoms with metallic atoms.

  8. Cell Structure Evolution of Aluminum Foams Under Reduced Pressure Foaming (United States)

    Cao, Zhuokun; Yu, Yang; Li, Min; Luo, Hongjie


    Ti-H particles are used to increase the gas content in aluminum melts for reduced pressure foaming. This paper reports on the RPF process of AlCa alloy by adding TiH2, but in smaller amounts compared to traditional process. TiH2 is completely decomposed by stirring the melt, following which reduced pressure is applied. TiH2 is not added as the blowing agent; instead, it is added for increasing the H2 concentration in the liquid AlCa melt. It is shown that pressure change induces further release of hydrogen from Ti phase. It is also found that foam collapse is caused by the fast bubble coalescing during pressure reducing procedure, and the instability of liquid film is related to the significant increase in critical thickness of film rupture. A combination of lower amounts of TiH2, coupled with reduced pressure, is another way of increasing hydrogen content in the liquid aluminum. A key benefit of this process is that it provides time to transfer the molten metal to a mold and then apply the reduced pressure to produce net shape foam parts.

  9. Metallic Hydrogen (United States)

    Silvera, Isaac; Zaghoo, Mohamed; Salamat, Ashkan


    Hydrogen is the simplest and most abundant element in the Universe. At high pressure it is predicted to transform to a metal with remarkable properties: room temperature superconductivity, a metastable metal at ambient conditions, and a revolutionary rocket propellant. Both theory and experiment have been challenged for almost 80 years to determine its condensed matter phase diagram, in particular the insulator-metal transition. Hydrogen is predicted to dissociate to a liquid atomic metal at multi-megabar pressures and T =0 K, or at megabar pressures and very high temperatures. Thus, its predicted phase diagram has a broad field of liquid metallic hydrogen at high pressure, with temperatures ranging from thousands of degrees to zero Kelvin. In a bench top experiment using static compression in a diamond anvil cell and pulsed laser heating, we have conducted measurements on dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K. We observe a first-order phase transition in the liquid phase, as well as sharp changes in optical transmission and reflectivity when this phase is entered. The optical signature is that of a metal. The mapping of the phase line of this transition is in excellent agreement with recent theoretical predictions for the long-sought plasma phase transition to metallic hydrogen. Research supported by the NSF, Grant DMR-1308641, the DOE Stockpile Stewardship Academic Alliance Program, Grant DE-FG52-10NA29656, and NASA Earth and Space Science Fellowship Program, Award NNX14AP17H.

  10. Multilayer Clad Plate of Stainless Steel/Aluminum/Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    YUAN Jiawei; PANG Yuhua; LI Ting


    The 3, 5, 20 layer clad plate from austenitic stainless steel, pure aluminum and aluminum alloy sheets were fabricated in different ways. The stretch and interface properties were measured. The result shows that 20 layer clad plate is better than the others. Well-bonded clad plate was successfully obtained in the following procedure: Basic clad sheet from 18 layer A11060/A13003sheets was firstly obtained with an initial rolling reduction of 44% at 450 ℃, followed by annealing at 300 ℃, and then with reduction of 50% at 550 ℃ from STS304 on each side. The best 20 layer clad plate was of 129 MPa bonding strength and 225 MPa stretch strength.

  11. Electrodeposition of aluminum on aluminum surface from molten salt

    Institute of Scientific and Technical Information of China (English)

    Wenmao HUANG; Xiangyu XIA; Bin LIU; Yu LIU; Haowei WANG; Naiheng MA


    The surface morphology,microstructure and composition of the aluminum coating of the electrodeposition plates in AlC13-NaC1-KC1 molten salt with a mass ratio of 8:1:1 were investigated by SEM and EDS.The binding force was measured by splat-cooling method and bending method.The results indicate that the coatings with average thicknesses of 12 and 9 μm for both plates treated by simple grinding and phosphating are compacted,continuous and well adhered respectively. Tetramethylammonium chloride (TMAC) can effectively prevent the growth of dendritic crystal,and the anode activation may improve the adhesion of the coating. Binding force analysis shows that both aluminum coatings are strongly adhered to the substrates.

  12. Casting structure of pure aluminum by electric pulse modification at different superheated temperatures

    Institute of Scientific and Technical Information of China (English)

    Jingang Qi; Jianzhong Wang; Xingjiang Liu; Bing Wang; Daqiang Cang


    Electric pulse modification (EPM) is a novel technique that reduces grain size by altering the structure of a melt. It was investigated that the response of the casting structure of high pure aluminum to EPM in different superheated melts. The results indicate that the grain refining effect of a given pulse electric field holds an optimal temperature range, moreover, a lower or higher superheated temperature will both disadvantage the improvements of casting structure. It essentially lies in the cooperative action between the distorted absorption of clusters and the activated capability of atoms in the aluminum melt.

  13. Determination of the dominant catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst system: Is it single-metal Rh₁Cp*-based, subnanometer Rh₄ cluster-based, or Rh(0)n nanoparticle-based cyclohexene hydrogenation catalysis at room temperature and mild pressures?

    Energy Technology Data Exchange (ETDEWEB)

    Bayram, Ercan [Colorado State Univ., Fort Collins, CO (United States); Linehan, John C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fulton, John L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szymczak, Nathaniel K. [Univ. of Michigan, Ann Arbor, MI (United States); Finke, Richard G. [Colorado State Univ., Fort Collins, CO (United States)


    Determining the kinetically dominant catalyst in a given catalytic system is a forefront topic in catalysis. The [RhCp*Cl₂]₂ (Cp* =[η⁵-C₅(CH₃)₅]) system pioneered by Maitlis and co-workers is a classic precatalyst system from which homogeneous mononuclear Rh₁, subnanometer Rh₄ cluster, and heterogeneous polymetallic Rh(0)n nanoparticle have all arisen as viable candidates for the true hydrogenation catalyst, depending on the precise substrate, H₂ pressure, temperature, and catalyst concentration conditions. Addressed herein is the question of whether the prior assignment of homogeneous, mononuclear Rh₁Cp*-based catalysis is correct, or are trace Rh₄ subnanometer clusters or possibly Rh(0)n nanoparticles the dominant, actual cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm initial H₂ pressure? The observation herein of Rh₄ species by in operando-X-ray absorption fine structure (XAFS) spectroscopy, at the only slightly more vigorous conditions of 26 °C and 8.3 atm H₂ pressure, and the confirmation of Rh₄ clusters by ex situ mass spectroscopy raises the question of the dominant, room temperature, and mild pressure cyclohexene hydrogenation catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst pioneered by Maitlis and co-workers. Ten lines of evidence are provided herein to address the nature of the true room temperature and mild pressure cyclohexene hydrogenation catalyst derived from [RhCp*Cl₂]₂. Especially significant among those experiments are quantitative catalyst poisoning experiments, in the present case using 1,10-phenanthroline. Those poisoning studies allow one to distinguish mononuclear Rh₁, subnanometer Rh₄ cluster, and Rh(0)n nanoparticle catalysis hypotheses. The evidence obtained provides a compelling case for a mononuclear, Rh₁Cp*-based cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm H₂ pressure. The resultant methodology, especially the quantitative

  14. Modeling dissolution in aluminum alloys (United States)

    Durbin, Tracie Lee


    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  15. 若干氢键团簇的纳秒和飞秒激光光电离及从头计算研究%Nanosecond and Femtosecond Laser Photoionization and Ab Initio Calculation Studies of Some Hydrogen Bonded Clusters

    Institute of Scientific and Technical Information of China (English)

    张柏林; 楼南泉; 王秀岩


    The multiphoton ionization and dissociation of azabenzenes-solvent clusters were studied using a time-of-flight mass spectrometer, nano- and femtosecond lasers. Due to the fact that the problem was resolved technically, the experiments about multiphoton ionization of pyrimidine-water in gas phase were performed successfully. The multiphoton ionization mass spectroscopy of the clusters was observed for the first time. The experimental results indicate sequences of protonated cluster ions are formed. Based on both ab initio calculations results and dependence of cluster ion intensity on the laser power, the processes of proton transfer and charge transfer within the clusters were presented. During the femtosecond laser photonionization of pyridine clusters, the coexistencephenomena of protonated and unprotonated cluster ions was observed first. The existence of pyridine dimmer ions and relevant calculation results indicate that the C-H…Nbonds can be formed between pyridine molecules, which corrected some reported results and also provided with a good example for the study of weak bond clusters. The multiphoton ionization results of pyrimidine-methanol and pyridazine-methanol clusters are presented for the first time. It is also found that only the protonated cluster ions are produced after clusters' ionization. The stable structures of all clusters were obtained theoretically, and the mechanisms and processes of proton transfer after ionization were elucidated.%利用纳秒和飞秒激光及飞行时间质谱仪对氮化苯-溶剂分子团簇的多光子电离和离解进行了研究.通过解决实验中的技术难题,实现了在气相条件下实验研究嘧啶与水团簇的多光子电离.首次观测到该团簇的多光子电离质谱,发现电离后形成了质子化团簇系列,通过团簇浓度随激光强度的变化以及理论计算,阐明了团簇内质子转移过程,以及电荷分布和质子转移过程随着团簇尺寸的变化;首次观测

  16. Interplay between experiments and calculations for organometallic clusters and caged clusters

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Atsushi [Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan); Nakajima Designer Nanocluster Assembly Project, ERATO, JST, KSP, 3-2-1 Sakado, Kawasaki 213-0012 (Japan); Keio Institute of Pure and Applied Sciences (KiPAS), Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522 (Japan)


    Clusters consisting of 10-1000 atoms exhibit size-dependent electronic and geometric properties. In particular, composite clusters consisting of several elements and/or components provide a promising way for a bottom-up approach for designing functional advanced materials, because the functionality of the composite clusters can be optimized not only by the cluster size but also by their compositions. In the formation of composite clusters, their geometric symmetry and dimensionality are emphasized to control the physical and chemical properties, because selective and anisotropic enhancements for optical, chemical, and magnetic properties can be expected. Organometallic clusters and caged clusters are demonstrated as a representative example of designing the functionality of the composite clusters. Organometallic vanadium-benzene forms a one dimensional sandwich structure showing ferromagnetic behaviors and anomalously large HOMO-LUMO gap differences of two spin orbitals, which can be regarded as spin-filter components for cluster-based spintronic devices. Caged clusters of aluminum (Al) are well stabilized both geometrically and electronically at Al{sub 12}X, behaving as a “superatom”.

  17. Low-temperature adsorption/storage of hydrogen on FAU, MFI, and MOR zeolites with various Si/Al ratios: effect of electrostatic fields and pore structures. (United States)

    Jhung, Sung Hwa; Yoon, Ji Woong; Lee, Ji Sun; Chang, Jong-San


    Several zeolites, such as faujasite, mordenite, and ZSM-5, with various aluminum contents have been used to analyze the effect of aluminum or cation concentration (strength of electrostatic field) on hydrogen adsorption at low temperature. Irrespective of the zeolite structure, the adsorption capacity, isosteric heat of adsorption (-DeltaHads), surface coverage, and micropore occupancy increase with increasing aluminum content of a zeolite. Zeolites with a higher amount of aluminum favorably adsorb hydrogen at relatively low pressures. For zeolites with similar aluminum contents, the adsorption capacity, isosteric heat of adsorption, surface coverage, and micropore occupancy are in the order of mordenite>ZSM-5>faujasite, probably due to differing pore sizes and the presence or absence of pore intersections. This work demonstrates that zeolites with strong electrostatic fields and narrow pores without intersections are beneficial for high hydrogen uptake.

  18. Hydrogen effect on the properties of sapphire (United States)

    Mogilevsky, Radion N.; Sharafutdinova, Liudmila G.; Nedilko, Sergiy; Gavrilov, Valeriy; Verbilo, Dmitriy; Mittl, Scott D.


    Sapphire is a widely used material for optical, electronic and semiconductor applications due to its excellent optical properties and very high durability. Optical and mechanical properties of sapphire depend on many factors such as the starting materials that are used to grow crystals, methods to grow sapphire crystals, etc. Demand for highest purity and quality of sapphire crystals increased ten fold for the last several years due to new applications for this material. In this work we studied the effect of starting materials and crystal growth methods on the optical and mechanical properties of sapphire, especially concentrating on the effect of hydrogen on the properties of sapphire. It was found that the infrared (IR) absorption which is traditionally used to measure the hydrogen content in sapphire crystals cannot be reliably used and the data obtained by this method provides a much lower hydrogen concentration than actual. We have shown for the first time that Nuclear Magnetic Resonance techniques can be successfully used to determine hydrogen concentration in sapphire crystals. We have shown that hydrogen concentration in sapphire can reach thousands of ppm if these crystals are grown from Verneuil starting material or aluminum oxide powder. Alternatively, the hydrogen concentration is very low if sapphire crystals are grown from High Purity Densified Alumina (HPDA®) as a starting material. HPDA® is produced by EMT, Inc through their proprietary patented technology. It was found that optical and mechanical properties of sapphire crystals grown using EMT HPDA® starting material are much better than those sapphire crystals grown using a starting material of Verneuil crystals or aluminum oxide powder.

  19. Fuzzy Clustering

    DEFF Research Database (Denmark)

    Berks, G.; Keyserlingk, Diedrich Graf von; Jantzen, Jan;


    and clustering are the basic concerns in medicine. Classification depends on definitions of the classes and their required degree of participant of the elements in the cases' symptoms. In medicine imprecise conditions are the rule and therefore fuzzy methods are much more suitable than crisp ones. Fuzzy c....... A symptom may belong to more than one class. For instance to the class of very severe disease and to the class of failure of awareness of the own disturbance. The description of language failures by c-mean classification of analyzed factors correspond in many but not in all cases to the traditional......-mean clustering is an easy and well improved tool, which has been applied in many medical fields. We used c-mean fuzzy clustering after feature extraction from an aphasia database. Factor analysis was applied on a correlation matrix of 26 symptoms of language disorders and led to five factors. The factors...

  20. Diffusion-bonded beryllium aluminum optical structures (United States)

    Grapes, Thomas F.


    Beryllium aluminum material can present significant advantages for optical support structures. A likely advantage of beryllium aluminum compared to aluminum or titanium for such structures is its higher specific stiffness. However, beryllium aluminum material is significantly more expensive than most competing materials. The cost problem with beryllium aluminum is exacerbated if fabrication methods that result in near net shape parts are not used. Near net shape methods result in the least amount of material "thrown away" in the fabrication process. Casting is a primary example of near net shape manufacturing that is appropriate for some optical support structures. Casting aluminum, and other materials as well, is common. Casting of beryllium aluminum is very difficult, however, and has not had significant success. Diffusion bonding - a different approach for achieving near net shape beryllium aluminum optical support structures, was pursued and accomplished. Diffusion bonding is a term used to describe the joining of solid metal pieces under high temperature and pressure, but without melting. Three different optical support structures were designed and built of beryllium aluminum using diffusion bonding. Relatively small solid beryllium aluminum pieces were arranged together and then joined under hot isostatic pressure conditions. The resulting relatively large pressure bonded part was then machined to achieve the final product. Significant cost savings as compared to machining the part from a solid block were realized. Difficulties achieving diffusion bonds in complex joints were experienced and addressed.

  1. Electrically Conductive Anodized Aluminum Surfaces (United States)

    Nguyen, Trung Hung


    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  2. Double-layer Modiifcation of Water-based Aluminum with SiO2 and Polyacrylic Acid by Sol-gel Process and in situPolymerization

    Institute of Scientific and Technical Information of China (English)

    HE Yuhang; LI Houbin


    A double-layer aluminum consisting of an aluminum core and a shell of SiO2 and polyacrylic acid was synthesized. This modiifed aluminum was used to improve the corrosion resistance and dispersive property of aluminum in waterborne media. TEM, FTIR, XPS, and EDX determination showed that PAA and SiO2 were coated on the surface of aluminum. Evolved hydrogen detection showed that the corrosion resistance of composite particle had been markedly improved. Maximum corrosion inhibition efifciency of SiO2 coated aluminum (SiO2@Al) was 95.1% while that of double-layer coated aluminum (PAA/SiO2@Al) was 98.8%. Meanwhile, polyacrylic acid layer improved the agglomeration of aluminum significantly. According to the dispersibility test, the particle size of 50% volume fraction [d(0.5)] of aluminum, SiO2@Al and PAA/SiO2@Al were 42, 53, and 34 μm, respectively.

  3. Electronic structures and thermodynamic stabilities of aluminum-based deuterides from first principles calculations

    Institute of Scientific and Technical Information of China (English)

    Ye Xiao-Qiu; Luo De-Li; Sang Ge; Ao Bing-Yun


    The alanates (complex aluminohydrides) have relatively high gravimetric hydrogen densities and are among the most promising solid-state hydrogen-storage materials. In this work, the electronic structures and the formation enthalpies of seven typical aluminum-based deuterides have been calculated by the plane-wave pseudopotential method,these being AID3, LiAID4, Li3AID6, BaAID5, Ba2AID7, LiMg(AID4)3 and LiMgAID6. The results show that all these compounds are large band gap insulators at 0 K with estimated band gaps from 2.31 eV in AID3 to 4.96 eV in LiMg(AID4)3. The band gaps are reduced when the coordination of Al varies from 4 to 6. Two peaks present in the valence bands are the common characteristics of aluminum-based deuterides containing AID4 subunits while three peaks are the common characteristics of those containing AID6 subunits. The electronic structures of these compounds are determined mainly by aluminum deuteride complexes (AID4 or AID6) and their mutual interactions. The predicted formation enthalpies are presented for the studied aluminum-based deuterides.


    Directory of Open Access Journals (Sweden)

    Josip Peko


    Full Text Available This study examined steel and aluminum variants of modern exhibition structures in which the main design requirements include low weight (increased span/depth ratio, transportation, and construction and durability (resistance to corrosion. This included a design situation in which the structural application of aluminum alloys provided an extremely convenient and practical solution. Viability of an aluminum structure depends on several factors and requires a detailed analysis. The overall conclusion of the study indicated that aluminum can be used as a structural material and as a viable alternative to steel for Croatian snow and wind load values and evidently in cases in which positive properties of aluminum are required for structural design. Furthermore, a structural fire analysis was conducted for an aluminum variant structure by using a zone model for realistic fire analysis. The results suggested that passive fire protection for the main structural members was not required in the event of areal fire with duration of 60 min.

  5. [Link between aluminum neurotoxicity and neurodegenerative disorders]. (United States)

    Kawahara, Masahiro


    Aluminum is an old element that has been known for a long time, but some of its properties are only now being discovered. Although environmentally abundant, aluminum is not essential for life; in fact, because of its specific chemical properties, aluminum inhibits more than 200 biologically important functions and exerts various adverse effects in plants, animals, and humans. Aluminum is a widely recognized neurotoxin. It has been suggested that there is a relationship between exposure to aluminum and neurodegenerative diseases, including dialysis encephalopathy, amyotrophic lateral sclerosis and parkinsonism dementia in the Kii Peninsula and Guam, as well as Alzheimer' s disease: however, this claim remains to be verified. In this chapter, we review the detailed characteristics of aluminum neurotoxicity and the link between Alzheimer' s disease and other neurodegenerative diseases, based on recent findings on metal-metal interactions and the functions of metalloproteins in synapses.

  6. Optical Transmittance of Anodically Oxidized Aluminum Alloy (United States)

    Saito, Mitsunori; Shiga, Yasunori; Miyagi, Mitsunobu; Wada, Kenji; Ono, Sachiko


    Optical transmittance and anisotropy of anodic oxide films that were made from pure aluminum and an aluminum alloy (A5052) were studied. The alloy oxide film exhibits an enhanced polarization function, particularly when anodization is carried out at a large current density. It was revealed by chemical analysis that the alloy oxide film contains a larger amount of unoxidized aluminum than the pure-aluminum oxide film. The polarization function can be elucidated by considering unoxidized aluminum particles that are arranged in the columnar structure of the alumina film. Electron microscope observation showed that many holes exist in the alloy oxide film, around which columnar cells are arranged irregularly. Such holes and irregular cell arrangement cause the increase in the amount of unoxidized aluminum, and consequently induces scattering loss.

  7. Hydrogen as a fuel

    Energy Technology Data Exchange (ETDEWEB)


    A panel of the Committee on Advanced Energy Storage Systems of the Assembly of Engineering has examined the status and problems of hydrogen manufacturing methods, hydrogen transmission and distribution networks, and hydrogen storage systems. This examination, culminating at a time when rapidly changing conditions are having noticeable impact on fuel and energy availability and prices, was undertaken with a view to determining suitable criteria for establishing the pace, timing, and technical content of appropriate federally sponsored hydrogen R and D programs. The increasing urgency to develop new sources and forms of fuel and energy may well impact on the scale and timing of potential future hydrogen uses. The findings of the panel are presented. Chapters are devoted to hydrogen sources, hydrogen as a feedstock, hydrogen transport and storage, hydrogen as a heating fuel, automotive uses of hydrogen, aircraft use of hydrogen, the fuel cell in hydrogen energy systems, hydrogen research and development evaluation, and international hydrogen programs.

  8. Effect of tunnel structure on the specific capacitance of etched aluminum foil

    Institute of Scientific and Technical Information of China (English)

    Ning Peng; Li-Bo Liang; Ye-Dong He; Hong-Zhou Song; Xiao-Fei Yang; Xiao-Yu Cai


    The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The maximum of specific capacitance and the cor-responding optimum values for tunnel sizes at various anodization voltages were predicted. The increased size distribution and taper of tun-nels were demonstrated to decrease the specific capacitance, whereas the addition of polymeric additive into the tunnel widening solution was demonstrated to increase the capacitance. The formation of merged tunnels on the etched aluminum surface, irrespective of the presence of row-merged tunnels or cluster-merged tunnels, resulted in a dramatic decrease in the specific capacitance. It is concluded that, enhancing the uniformity of tunnel size and distribution and avoiding the formation of merged tunnels are the effective approach to achieving the higher capacitance for the tunnel etched and formed aluminum foil.

  9. The hydrogen; L'hydrogene

    Energy Technology Data Exchange (ETDEWEB)



    The hydrogen as an energy system represents nowadays a main challenge (in a scientific, economical and environmental point of view). The physical and chemical characteristics of hydrogen are at first given. Then, the challenges of an hydrogen economy are explained. The different possibilities of hydrogen production are described as well as the distribution systems and the different possibilities of hydrogen storage. Several fuel cells are at last presented: PEMFC, DMFC and SOFC. (O.M.)

  10. Hydrogen Peroxide Storage in Small Sealed Tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.


    Unstabilized hydrogen peroxide of 85% concentration has been prepared in laboratory quantities for testing material compatibility and long term storage on a small scale. Vessels made of candidate tank and liner materials ranged in volume from 1 cc to 2540 cc. Numerous metals and plastics were tried at the smallest scales, while promising ones were used to fabricate larger vessels and liners. An aluminum alloy (6061-T6) performed poorly, including increasing homogeneous decay due to alloying elements entering solution. The decay rate in this high strength aluminum was greatly reduced by anodizing. Better results were obtained with polymers, particularly polyvinylidene fluoride. Data reported herein include ullage pressures as a function of time with changing decay rates, and contamination analysis results.

  11. Observations of Distant Clusters (United States)

    Donahue, Megan


    The is the proceedings and papers supported by the LTSA grant: Homer, D. J.\\& Donahue, M. 2003, in "The Emergence of Cosmic Structure": 13'h Astrophysics Conference Proceedings, Vol. 666,3 1 1-3 14, (AIP). Baumgartner, W. H., Loewenstein, M., Horner, D. J., Mushotzky, R. F. 2003, HEAD- AAS, 35.3503. Homer, D. J. , Donahue, M., Voit G. M. 2003, HEAD-AAS, 35.1309. Nowak, M. A., Smith, B., Donahue, M., Stocke, J. 2003, HEAD-AAS, 35.1316. Scott, D., Borys, C., Chapman, S. C., Donahue, M., Fahlman, G. G., Halpem, M. Newbury, P. 2002, AAS, 128.01. Jones, L. R. et al. 2002, A new era in cosmology, ASP Conference Proceedings, Vol. 283, p. 223 Donahue, M., Daly, R. A., Homer, D. J. 2003, ApJ, 584, 643, Constraints on the Cluster Environments and Hotspot magnetic field strengths for radio sources 3280 and 3254. Donahue, M., et al. 2003, ApJ, 598, 190. The mass, baryonic fraction, and x-ray temperature of the luminous, high-redshift cluster of galaxies MS045 1.6-0305 Perlman, E. S. et al. 2002, ApJS, 140, 256. Smith, B. J., Nowak, M., Donahue, M., Stocke, J. 2003, AJ, 126, 1763. Chandra Observations of the Interacting NGC44 10 Group of Galaxies. Postman, M., Lauer, T. R., Oegerle, W., Donahue, M. 2002, ApJ, 579, 93. The KPNO/deep-range cluster survey I. The catalog and space density of intermediate-redshift clusters. Molnar, S. M., Hughes, J. P., Donahue, M., Joy, M. 2002, ApJ, 573, L91, Chandra Observations of Unresolved X-Ray Sources around Two Clusters of Galaxies. Donahue, M., Mack, J., 2002 NewAR, 46, 155, HST NIcmos and WFPC2 observations of molecular hydrogen and dust around cooling flows. Koekemoer, A. M. et al. 2002 NewAR, 46, 149, Interactions between the A2597 central radio source and dense gas host galaxy. Donahue, M. et al. 2002 ApJ, 569,689, Distant cluster hunting II.

  12. Experimental studies of thermal and chemical interactions between molten aluminum and water

    Energy Technology Data Exchange (ETDEWEB)

    Farahani, A.A.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States)


    The possibility of rapid physical and chemical aluminum/water interactions during a core melt accident in a noncommercial reactor (e.g., HFIR, ATR) has resulted in extensive research to determine the mechanism by which these interactions occur and propagate on an explosive time scale. These events have been reported in nuclear testing facilities, i.e., during SPERT 1D experiment, and also in aluminum casting industries. Although rapid chemical reactions between molten aluminum and water have been subject of many studies, very few reliable measurements of the extent of the chemical reactions have thus far been made. We have modified an existing 1-D shock tube facility to perform experiments in order to determine the extent of the explosive thermal/chemical interactions between molton aluminum and water by measuring important physical quantities such as the maximum dynamic pressure and the amount of the generated hydrogen. Experimental results show that transient pressures greater than 69 MPa with a rise time of less than 125 {mu}sec can occur as the result of the chemical reaction of 4.2 grams of molton aluminum (approximately 15% of the total mass of the fuel of 28 grams) at 980 C with room temperature water.

  13. Development Of A Novel Discontinuously-Reinforced Aluminum For Space Applications (United States)

    Pandey, A. B.; Shah, S.; Shadoan, M.


    Discontinuously-reinforced aluminum (DRA) has been used in aerospace structures such as Ventral Fins and Fan Exit Guide Vanes owing to its superior specific stiffness, specific strength, wear resistance, and thermal resistance as compared to the unreinforced aluminum alloys. In order to reduce engine weight, DRA materials are now being considered for space applications. Higher specific strength at ambient and cryogenic temperatures is one of the main requirements in certain rocket applications. The commercial DRA materials use 6xxx and 2xxx precipitation hardened aluminum alloys as matrices which have limited strengths. Therefore, an aluminum alloy which can provide significantly higher ambient and cryogenic strengths is required. In this paper, a novel aluminum alloy based on Al-Sc-X composition with improved ambient and cryogenic temperature strengthening capability is proposed. In addition, this alloy showed promise for improved strength at elevated temperature. The monolithic alloy and the composite with 15 volume percent SiC and B4C particles were processed using a powder metallurgy approach. The influence of processing parameters on the microstructures and mechanical properties of the monolithic and composite materials is discussed. The alloy showed very high strength and moderate ductility. The influence of hydrogen on the properties of monolithic and composite materials is discussed. The thermal stability of these materials is also evaluated. The strength of the material is discussed in terms of solid solution strengthening, Orowan strengthening, and antiphase boundary strengthening models.

  14. Aluminum-stabilized NB3SN superconductor (United States)

    Scanlan, Ronald M.


    An aluminum-stabilized Nb.sub.3 Sn superconductor and process for producing same, utilizing ultrapure aluminum. Ductile components are co-drawn with aluminum to produce a conductor suitable for winding magnets. After winding, the conductor is heated to convert it to the brittle Nb.sub.3 Sn superconductor phase, using a temperature high enough to perform the transformation but still below the melting point of the aluminum. This results in reaction of substantially all of the niobium, while providing stabilization and react-in-place features which are beneficial in the fabrication of magnets utilizing superconducting materials.

  15. Investigations of Aluminum-Doped Self-Healing Zircaloy Surfaces in Context of Accident-Tolerant Fuel Cladding Research (United States)

    Carr, James; Vasudevamurthy, Gokul; Snead, Lance; Hinderliter, Brian; Massey, Caleb


    We present here some important results investigating aluminum as an effective surface dopant for increased oxidation resistance of zircaloy nuclear fuel cladding. At first, the transport behavior of aluminum into reactor grade zircaloy was studied using simple diffusion couples at temperatures greater than 770 K. The experiments revealed the formation of tens of microns thick graded Zr-Al layers. The activation energy of aluminum in zircaloy was found to be ~175 kJ/mol (~1.8 eV), indicating the high mobility of aluminum in zircaloy. Subsequently, aluminum sputter-coated zircaloy coupons were heat-treated to achieve surface doping and form compositionally graded layers. These coupons were then tested in steam environments at 1073 and 1273 K. The microstructure of the as-fabricated and steam-corroded specimens was compared to those of pure zircaloy control specimens. Analysis of data revealed that aluminum effectively competed with zircaloy for oxygen up until 1073 K blocking oxygen penetration, with no traces of large scale spalling, indicating mechanically stable interfaces and surfaces. At the highest steam test temperatures, aluminum was observed to segregate from the Zr-Al alloy under layers and migrate to the surface forming discrete clusters. Although this is perceived as an extremely desirable phenomenon, in the current experiments, oxygen was observed to penetrate into the zirconium-rich under layers, which could be attributed to formation of surface defects such as cracks in the surface alumina layers.

  16. Quotients of cluster categories


    Jorgensen, Peter


    Higher cluster categories were recently introduced as a generalization of cluster categories. This paper shows that in Dynkin types A and D, half of all higher cluster categories are actually just quotients of cluster categories. The other half can be obtained as quotients of 2-cluster categories, the "lowest" type of higher cluster categories. Hence, in Dynkin types A and D, all higher cluster phenomena are implicit in cluster categories and 2-cluster categories. In contrast, the same is not...

  17. A Statistical Theory for Hydrogen Bonding Networks: One Component Case

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-Jun; BA Xin-Wu; ZHAO Min; LI Ze-Sheng


    The theory of reversible gelation is shown to be applicable to the hydrogen bonding system by analyzing their similarities in statistical viewpoint. The size distribution of hydrogen bonding clusters, the gelation condition and the generalized scaling law can be obtained directly. These results show that such a system can undergo phase transition process. Furthermore, a relationship between Gibbs free energy of forming hydrogen bond and conversions of groups is given. As an example, the chemical shift of OH groups is considered.

  18. Silicon reduces aluminum accumulation in rats: relevance to the aluminum hypothesis of Alzheimer disease. (United States)

    Bellés, M; Sánchez, D J; Gómez, M; Corbella, J; Domingo, J L


    In recent years, a possible relation between the aluminum and silicon levels in drinking water and the risk of Alzheimer disease (AD) has been established. It has been suggested that silicon may have a protective effect in limiting oral aluminum absorption. The present study was undertaken to examine the influence of supplementing silicon in the diet to prevent tissue aluminum retention in rats exposed to oral aluminum. Three groups of adult male rats were given by gavage 450 mg/kg/day of aluminum nitrate nonahydrate 5 days a week for 5 weeks. Concurrently, animals received silicon in the drinking water at 0 (positive control), 59, and 118 mg Si/L. A fourth group (-Al, - Si) was designated as a negative control group. At the end of the period of aluminum and silicon administration, urines were collected for 4 consecutive days, and the urinary aluminum levels were determined. The aluminum concentrations in the brain (various regions), liver, bone, spleen, and kidney were also measured. For all tissues, aluminum levels were significantly lower in the groups exposed to 59 and 118 mg Si/L than in the positive control group; significant reductions in the urinary aluminum levels of the same groups were also found. The current results corroborate that silicon effectively prevents gastrointestinal aluminum absorption, which may be of concern in protecting against the neurotoxic effects of aluminum.

  19. The Aluminum Deep Processing Project of North United Aluminum Landed in Qijiang

    Institute of Scientific and Technical Information of China (English)


    <正>On April 10,North United Aluminum Company respectively signed investment cooperation agreements with Qijiang Industrial Park and Qineng Electricity&Aluminum Co.,Ltd,signifying the landing of North United Aluminum’s aluminum deep processing project in Qijiang.

  20. Theoretical Studies of Hydrogen Storage Alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, Hannes


    Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgH{sub 2} is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i) the binding energy of the hydrogen atoms in the hydride is too large, causing the release temperature to be too high, and (ii) the diffusion of hydrogen through the hydride is so slow that loading of hydrogen into the metal takes much too long. In the first year of the project, we found that the addition of ca. 15% of aluminum decreases the binding energy to the hydrogen to the target value of 0.25 eV which corresponds to release of 1 bar hydrogen gas at 100 degrees C. Also, the addition of ca. 15% of transition metal atoms, such as Ti or V, reduces the formation energy of interstitial H-atoms making the diffusion of H-atoms through the hydride more than ten orders of magnitude faster at room temperature. In the second year of the project, several calculations of alloys of magnesium with various other transition metals were carried out and systematic trends in stability, hydrogen binding energy and diffusivity established. Some calculations of ternary alloys and their hydrides were also carried out, for example of Mg{sub 6}AlTiH{sub 16}. It was found that the binding energy reduction due to the addition of aluminum and increased diffusivity due to the addition of a transition metal are both effective at the same time. This material would in principle work well for hydrogen storage but it is, unfortunately, unstable with respect to phase separation. A search was made for a ternary alloy of this type where both the alloy and the corresponding hydride are stable. Promising results were obtained by including Zn in the alloy.

  1. Regional Innovation Clusters (United States)

    Small Business Administration — The Regional Innovation Clusters serve a diverse group of sectors and geographies. Three of the initial pilot clusters, termed Advanced Defense Technology clusters,...

  2. Ab initio Calculations of Optical Properties of Clusters

    CERN Document Server

    Shinde, Ravindra


    We have performed systematic large-scale all-electron correlated calculations on boron Bn, aluminum Aln and magnesium Mgn clusters (n=2--5), to study their linear optical absorption spectra. Several possible isomers of each cluster were considered, and their geometries were optimized at the coupled-cluster singles doubles (CCSD) level of theory. Using the optimized ground-state geometries, excited states of different clusters were computed using the multi-reference singles-doubles configuration interaction (MRSDCI) approach, which includes electron correlation effects at a sophisticated level. These CI wavefunctions were used to compute the transition dipole matrix elements connecting the ground and various excited states of different clusters, eventually leading to their linear absorption spectra. The convergence of our results with respect to the basis sets, and the size of the CI expansion was carefully examined. Isomers of a given cluster show a distinct signature spectrum, indicating a strong structure p...

  3. Cluster forcing

    DEFF Research Database (Denmark)

    Christensen, Thomas Budde

    -industrialism and the ‘liveable' region. In this paper the cluster strategies that have been applied to the automotive sector in Wales are analysed. The paper includes a theoretical discussion on how the cluster concept has been applied to industrial policies, along with an empirical analysis of the application of the concept...... automotive sector in Wales. The paper draws from a survey of Welsh automotive suppliers on the characteristics of the local business environment and innovation. On the basis of the survey it is concluded that the public sector has an important task ahead concerning the linkages between universities and local...... businesses. The universities were not considered by the participating companies to be important parts of the local business environment and inputs from universities did not appear to be an important source to access knowledge about new product development or new techniques in production, distribution...

  4. Laboratory Powder Metallurgy Makes Tough Aluminum Sheet (United States)

    Royster, D. M.; Thomas, J. R.; Singleton, O. R.


    Aluminum alloy sheet exhibits high tensile and Kahn tear strengths. Rapid solidification of aluminum alloys in powder form and subsequent consolidation and fabrication processes used to tailor parts made of these alloys to satisfy such specific aerospace design requirements as high strength and toughness.

  5. Sanmenxia strives to create aluminum industrial base

    Institute of Scientific and Technical Information of China (English)


    <正>Contradiction between rich alumina resource and relatively weak electrolytic aluminum production capacity is the "bottleneck" inhibiting development of aluminum industry in San-menxia. During the period of "11th Five-Year Development", Sanmenxia will relay on its

  6. Wilson's disease; increased aluminum in liver. (United States)

    Yasui, M; Yoshimasu, F; Yase, Y; Uebayashi, Y


    Interaction of trace metal metabolism was studied in a patient with Wilson's dease. Atomic absorption analysis showed markedly increased urinary excretion of copper and aluminum and an increased aluminum content was found in the biopsied liver by neutron activation analysis. These findings suggest a complicated pathogenetic mechanism involving other metals besides copper in the Wilson's disease.

  7. Recrystallization in Commercially Pure Aluminum

    DEFF Research Database (Denmark)

    Bay, Bent; Hansen, Niels


    Recrystallization behavior in commercial aluminum with a purity of 99.4 pct was studied by techniques such as high voltage electron microscopy, 100 kV transmission electron microscopy, and light microscopy. Sample parameters were the initial grain size (290 and 24 microns) and the degree of defor......Recrystallization behavior in commercial aluminum with a purity of 99.4 pct was studied by techniques such as high voltage electron microscopy, 100 kV transmission electron microscopy, and light microscopy. Sample parameters were the initial grain size (290 and 24 microns) and the degree...... (FeAl3), which start to become operative when the degree of deformation is raised from 15 to 30 pct. The temperature of nucleation and of recrystallization decreases when the degree of deformation is increased and the initial grain size is decreased. The recrystallized grain size follows the same...... trend and it is observed that the refinement of the recrystallized grain size caused by an increasing degree of deformation and decreasing initial grain size is enhanced by the FeAl3 particles (when the degree of deformation is raised from 15 to 30 pct). Finally, the structural and kinetic observations...

  8. Aluminum honeycomb impact limiter study

    Energy Technology Data Exchange (ETDEWEB)

    Yaksh, M.C.; Thompson, T.C. (Nuclear Assurance Corp., Norcross, GA (United States)); Nickell, R.E. (Applied Science and Technology, Inc., Poway, CA (United States))


    Design requirements for a cask transporting radioactive materials must include the condition of the 30-foot free fall of the cask onto an unyielding surface. To reduce the deceleration loads to a tolerable level for all the components of the cask, a component (impact limiter) is designed to absorb the kinetic energy. The material, shape, and method of attachment of the impact limiter to the cask body comprises the design of the impact limiter. The impact limiter material of interest is honeycomb aluminum, and the particular design examined was for the NAC Legal Weight Truck cask (NAC-LWT) for spent fuel from light water reactors. The NAC-LWT has a design weight of 52,000 pounds, and it has a nominal length of 200 inches. The report describes the numerical calculations embodied in the FADE program to determine the accelerations and crush strain resulting from an arbitrary height and angle of orientation. Since the program serves as a design tool, static tests are performed to assess the effect of the shell containing the honeycomb aluminum. The static tests and their results are contained in the study. The static tests are used to demonstrate for licensing purposes the level of accelerations imposed on the cask during a 30-foot drop. 3 refs., 41 figs., 15 tabs.

  9. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail:; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna


    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  10. Gating of Permanent Molds for ALuminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang


    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  11. Gelling nature of aluminum soaps in oils. (United States)

    Wang, Xiaorong; Rackaitis, Mindaugas


    Aluminum soaps are notable for their ability to form soap-hydrocarbon gels of high viscosity. For more than half a century, it has been believed that the gelling mechanism is due to a formation of polymeric chains of aluminum molecules with the aluminum atoms linking along the axis and with the fatty acid chain extended sideways. Here we report results from an investigation using high-resolution electron microscopy and rheology measurements that clearly resolve the ambiguity. Our results reveal that the gelling mechanism stems from the formation of spherical nano-sized micelles from aluminum soap molecules, and those colloidal micelle particles then aggregate into networks of highly fractal and jammed structures. The earlier proposed polymer chain-like structure is definitely incorrect. The discovery of aluminum soap particles could expand application of these materials to new technologies.

  12. Aluminum-based metal-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Friesen, Cody A.; Martinez, Jose Antonio Bautista


    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.

  13. Proposal of recycling system for waste aluminum

    Directory of Open Access Journals (Sweden)

    Š. Valenčík


    Full Text Available Introduced work is focused on waste aluminum recycling process with objective to propose complex production system for recovering of aluminum and some aluminum alloys. Solution is supported by extended analysis concerning purpose, basis and system sequences for recyclation. Based on that, sources, possibilities and conditions for recycling are formed. This has been used in proposal of manufacturing system. The principle is the structural proposal of manufacturing system, which does not only differentiate the stage of aluminum melting process, but also related stages as gross separation, sizing, containerisation and batching, palletisation, stacking and some related operations. Production system respects technological specifications, requirements for rationalisation of manufacturing systems, technical and economical feasibility conditions and is considered in lower automation level. However production system solves complex problem of recycling of some types of aluminum, it improves flexibility, production, quality (melting by high enforcements and in protective atmosphere and extention of production (final products production.

  14. Trends in the global aluminum fabrication industry (United States)

    Das, Subodh; Yin, Weimin


    The aluminum fabrication industry has become more vital to the global economy as international aluminum consumption has grown steadily in the past decades. Using innovation, value, and sustainability, the aluminum industry is strengthening its position not only in traditional packaging and construction applications but also in the automotive and aerospace markets to become more competitive and to face challenges from other industries and higher industrial standards. The aluminum fabrication industry has experienced a significant geographical shift caused by rapid growth in emerging markets in countries such as Brazil, Russia, India, and China. Market growth and distribution will vary with different patterns of geography and social development; the aluminum industry must be part of the transformation and keep pace with market developments to benefit.

  15. Aluminum phosphate shows more adjuvanticity than Aluminum hydroxide in recombinant hepatitis –B vaccine formulation

    Directory of Open Access Journals (Sweden)


    Full Text Available Background: Although a number of investigation have been carried out to find alternative adjuvants to aluminum salts in vaccine formulations, they are still extensively used due to their good track record of safety, low cost and proper adjuvanticity with a variety of antigens. Adsorption of antigens onto aluminum compounds depends heavily on electrostatic forces between adjuvant and antigen. Commercial recombinant protein hepatitis B vaccines containing aluminum hydroxide as adjuvant is facing low induction of immunity in some sections of the vaccinated population. To follow the current global efforts in finding more potent hepatitis B vaccine formulation, adjuvanticity of aluminum phosphate has been compared to aluminum hydroxide. Materials and methods: The adjuvant properties of aluminum hydroxide and aluminum phosphate in a vaccine formulation containing a locally manufactured hepatitis B (HBs surface antigen was evaluated in Balb/C mice. The formulations were administered intra peritoneally (i.p. and the titers of antibody which was induced after 28 days were determined using ELISA technique. The geometric mean of antibody titer (GMT, seroconversion and seroprotection rates, ED50 and relative potency of different formulations were determined. Results: All the adjuvanicity markers obtained in aluminum phosphate formulation were significantly higher than aluminum hydroxide. The geometric mean of antibody titer of aluminum phosphate was approximately three folds more than aluminum hydroxide. Conclusion: Aluminum phosphate showed more adjuvanticity than aluminum hydroxide in hepatitis B vaccine. Therefore the use of aluminum phosphate as adjuvant in this vaccine may lead to higher immunity with longer duration of effects in vaccinated groups.

  16. Small Al clusters on the Cu(111) surface: Atomic relaxation and vibrational properties (United States)

    Rusina, G. G.; Borisova, S. D.; Chulkov, E. V.


    The relaxation and vibrational properties of both Al clusters and the (111) surface of a copper sub-strate were studied using the interatomic interaction potentials obtained in a tight-binding approximation. The presence of small aluminum clusters led to modification of the vibrational states of the substrate, a shift of the Rayleigh mode, and excitation of new Z-polarized modes. Hybridized modes localized on the cluster adatoms and the neighboring atoms of the substrate were found in the phonon spectrum. The localized dipole-active modes of the cluster and their strong hybridization with vibrations of the substrate points to desorption stability of the tri- and heptaatomic clusters.

  17. Characterization of aluminum surfaces: Sorption and etching (United States)

    Polkinghorne, Jeannette Clera

    Aluminum, due to its low density and low cost, is a key material for future lightweight applications. However, like other structural materials, aluminum is subject to various forms of corrosion damage that annually costs the United States approximately 5% of its GNP [1]. The main goal is to investigate the effects of various solution anions on aluminum surfaces, and specifically probe pit initiation and inhibition. Using surface analysis techniques including X-ray photoelectron spectroscopy, Auger electron spectroscopy, and scanning electron microscopy, results have been correlated with those obtained from electrochemical methods and a radiolabeling technique developed in the Wieckowski laboratory. Analysis of data has indicated that important variables include type of anion, solution pH, and applied electrode potential. While aggressive anions such as chloride are usually studied to elucidate corrosion processes to work ultimately toward inhibition, its corrosive properties can be successfully utilized in the drive for higher energy and smaller-scale storage devices. Fundamental information gained regarding anion interaction with the aluminum surface can be applied to tailor etch processes. Standard electrochemical techniques and SEM are respectively used to etch and analyze the aluminum substrate. Aluminum electrolytic capacitors are comprised of aluminum anode foil covered by an anodically grown aluminum oxide dielectric film, electrolytic paper impregnated with electrolyte, and aluminum cathode foil. Two main processes are involved in the fabrication of aluminum electrolytic capacitors, namely etching and anodic oxide formation. Etching of the anode foil results in a higher surface area (up to 20 times area enlargement compared to unetched foil) that translates into a higher capacitance gain, permitting more compact and lighter capacitor manufacture. Anodic oxide formation on the anode, creates the required dielectric to withstand high voltage operation. A

  18. Final Report: Metal Perhydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J-Y.; Shi, S.; Hackney, S.; Swenson, D.; Hu, Y.


    H molecule contains one hydrogen atom because the valence of a Li ion is +1. One MgH2 molecule contains two hydrogen atoms because the valence of a Mg ion is +2. In metal perhydrides, a molecule could contain more hydrogen atoms than expected based on the metal valance, i.e. LiH1+n and MgH2+n (n is equal to or greater than 1). When n is sufficiently high, there will be plenty of hydrogen storage capacity to meet future requirements. The existence of hydrogen clusters, Hn+ (n = 5, 7, 9, 11, 13, 15) and transition metal ion-hydrogen clusters, M+(H2)n (n = 1-6), such as Sc(H2)n+, Co(H2)n+, etc., have assisted the development of this concept. Clusters are not stable species. However, their existence stimulates our approach on using electric charges to enhance the hydrogen adsorption in a hydrogen storage system in this study. The experimental and modeling work to verify it are reported here. Experimental work included the generation of cold hydrogen plasma through a microwave approach, synthesis of sorbent materials, design and construction of lab devices, and the determination of hydrogen adsorption capacities on various sorbent materials under various electric field potentials and various temperatures. The results consistently show that electric potential enhances the adsorption of hydrogen on sorbents. NiO, MgO, activated carbon, MOF, and MOF and platinum coated activated carbon are some of the materials studied. Enhancements up to a few hundred percents have been found. In general, the enhancement increases with the electrical potential, the pressure applied, and the temperature lowered. Theoretical modeling of the hydrogen adsorption on the sorbents under the electric potential has been investigated with the density functional theory (DFT) approach. It was found that the interaction energy between hydrogen and sorbent is increased remarkably when an electric field is applied. This increase of binding energy offers a potential solution for DOE when looking for a compromise

  19. Multiphoton ionization of large water clusters. (United States)

    Apicella, B; Li, X; Passaro, M; Spinelli, N; Wang, X


    Water clusters are multimers of water molecules held together by hydrogen bonds. In the present work, multiphoton ionization in the UV range coupled with time of flight mass spectrometry has been applied to water clusters with up to 160 molecules in order to obtain information on the electronic states of clusters of different sizes up to dimensions that can approximate the bulk phase. The dependence of ion intensities of water clusters and their metastable fragments produced by laser ionization at 355 nm on laser power density indicates a (3+1)-photon resonance-enhanced multiphoton ionization process. It also explains the large increase of ionization efficiency at 355 nm compared to that at 266 nm. Indeed, it was found, by applying both nanosecond and picosecond laser ionization with the two different UV wavelengths, that no water cluster sequences after n = 9 could be observed at 266 nm, whereas water clusters up to m/z 2000 Th in reflectron mode and m/z 3000 Th in linear mode were detected at 355 nm. The agreement between our findings on clusters of water, especially true in the range with n > 10, and reported data for liquid water supports the hypothesis that clusters above a critical dimension can approximate the liquid phase. It should thus be possible to study clusters just above 10 water molecules, for getting information on the bulk phase structure.

  20. Transition-metal-doped aluminum hydrides as building blocks for supramolecular assemblies. (United States)

    Liu, Jianjun; Yu, Jiamei; Ge, Qingfeng


    Density functional theory calculations were carried out to characterize a series of transition-metal-doped aluminum hydrides, forming TMAl(n)H(2n) and TMAl(n)H(2n+1) (TM = Sc, Ti, V; n = 3,4), in either charged or neutral form. A new electron-counting rule for these clusters was formulated as PSEN (paired skeleton electron number) = 4n, which can characterize both closed-shell and open-shell clusters. On the basis of this electron-counting rule, the superatomic clusters such as TiAl(4)H(9) and TiAl(3)H(6) were identified and can be used to assemble supramolecular structures. Electronic structure analysis showed that three-centered TM-H-Al bonds largely contributed to the structural stability. Also, the spin state of a wide range of clusters in their ground state can be predicted by the electron-counting rule.

  1. A computational study on novel carbon-based lithium materials for hydrogen storage and the role of carbon in destabilizing complex metal hydrides (United States)

    Ghouri, Mohammed Minhaj

    One of the major impediments in the way of the realization of hydrogen economy is the storage of hydrogen gas. This involves both the storage for stationary applications as well as that of storage onboard vehicles for transportation applications. For obvious reasons, the system targets for the automotive applications are more stringent. There are many approaches which are still being researched for the storage of hydrogen for vehicular applications. Among them are the high pressure storage of hydrogen gas and the storing of liquid hydrogen in super insulated cryogenic cylinders. While both of them have been demonstrated practically, the high stakes of their respective shortcomings is hindering the wide spread application of these methods. Thus different solid state storage materials are being looked upon as promising solutions. Metal hydrides are a class of solid state hydrogen storage materials which are formed by the reaction of metals or their alloys with hydrogen. These materials have very good gravimetric storage densities, but are very stable thermodynamically to desorp hydrogen at room temperatures. Research is going on to improve the thermodynamics and the reaction kinetics of different metal hydrides. This dissertation tries to address the problem of high thermodynamic stability of the existing metal hydrides in two ways. First, a novel carbon based lithium material is proposed as a viable storage option based on its promising thermodynamic heat of formation. Pure beryllium (Be) clusters and the carbon-beryllium (C-Be) clusters are studied in detail using the Density Functional Theory (DFT) computational methods. Their interactions with hydrogen molecule are further studied. The results of these calculations indicate that hydrogen is more strongly physisorbed to the beryllium atom in the C-Be cluster, rather than to a carbon atom. After these initial studies, we calculated the geometries and the energies of more than 100 different carbon based lithium

  2. An Automatic Clustering Technique for Optimal Clusters

    CERN Document Server

    Pavan, K Karteeka; Rao, A V Dattatreya; 10.5121/ijcsea.2011.1412


    This paper proposes a simple, automatic and efficient clustering algorithm, namely, Automatic Merging for Optimal Clusters (AMOC) which aims to generate nearly optimal clusters for the given datasets automatically. The AMOC is an extension to standard k-means with a two phase iterative procedure combining certain validation techniques in order to find optimal clusters with automation of merging of clusters. Experiments on both synthetic and real data have proved that the proposed algorithm finds nearly optimal clustering structures in terms of number of clusters, compactness and separation.

  3. Tribology in Gaseous Hydrogen (United States)

    Sawae, Yoshinori; Sugimura, Joich

    Hydrogen is expected as a clean and renewable energy carrier for future environment-friendly society. Many machine elements in hydrogen energy systems should be operating within hydrogen gas and tribological behavior, such as friction and wear, of bearings and seals are affected by the hydrogen environment through some interactions between material surfaces and gaseous hydrogen, i.e., physisorption of hydrogen molecules and following chemisorptions of dissociated atoms on metal surfaces, formation of metal hydride and reduction of metal oxide layer by hydrogen atoms diffused into bulk. Therefore, friction and wear characteristics of tribomaterials in the hydrogen environment should be appropriately understood to establish a design guideline for reliable hydrogen utilizing systems. This paper reviews the current knowledge about the effect of hydrogen on friction and wear of materials, and then describes our recent progress of hydrogen research in the tribology field.

  4. Hydrogen sulphide. (United States)

    Guidotti, T L


    Hydrogen sulphide (H2S) is the primary chemical hazard in natural gas production in 'sour' gas fields. It is also a hazard in sewage treatment and manure-containment operations, construction in wetlands, pelt processing, certain types of pulp and paper production, and any situation in which organic material decays or inorganic sulphides exist under reducing conditions. H2S dissociates into free sulphide in the circulation. Sulphide binds to many macromolecules, among them cytochrome oxidase. Although this is undoubtedly an important mechanism of toxicity due to H2S, there may be others H2S provides little opportunity for escape at high concentrations because of the olfactory paralysis it causes, the steep exposure-response relationships, and the characteristically sudden loss of consciousness it can cause which is colloquially termed 'knockdown.' Other effects may include mucosal irritation, which is associated at lower concentrations with a keratoconjunctivitis called 'gas eye' and at higher concentrations with risk of pulmonary oedema. Chronic central nervous system sequelae may possibly follow repeated knockdowns: this is controversial and the primary effects of H2S may be confounded by anoxia or head trauma. Treatment is currently empirical, with a combination of nitrite and hyperbaric oxygen preferred. The treatment regimen is not ideal and carries some risk.

  5. Development of Alcoa aluminum foam products

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, J.D.; Crowley, M.D.; Wang, W.; Wilhelmy, D.M.; Hunter, D.E. [Alcoa Technical Center, Alcoa Center, PA (United States)


    A new lightweight aluminum foam product was described. The foam was made through the controlled decomposition of carbonate powders within molten aluminum and was able to resist both coalescence and drainage. The fine-celled aluminum foam derived its physical and mechanical properties from the properties of the aluminum alloy matrix from which they were produced. The rheology of the molten aluminum was modified to provide a superior mesostructure. Stabilization was achieved by creating a solid-gas-liquid suspension initiated by the addition of carbonates into an aluminum alloy melt. A cascade of chemical reactions then occurred within the melt to create a foamable suspension. Carbon monoxide (CO) was generated to initiate an additional sequence of chemical reactions which resulted in the formation of solid particles within the liquid metal. CO reacted with liquid Al to form graphite. The graphite then reacted with Al to form aluminum carbide (Al{sub 4}C{sub 3}). The microstructural, mesostructural, and mechanical character of the foams produced under different processing conditions were examined. Details of experimental test procedures were also described. It was concluded that the specific crush energy absorption was as high as 20 kJ/kg. The foam exhibited a bending stiffness that was approximately 20 to 30 times higher than balsa and polymer foams. 14 refs., 2 tabs., 7 figs.

  6. Method and apparatus for hydrogen production from water (United States)

    Muradov, Nazim Z. (Inventor)


    A method, apparatuses and chemical compositions are provided for producing high purity hydrogen from water. Metals or alloys capable of reacting with water and producing hydrogen in aqueous solutions at ambient conditions are reacted with one or more inorganic hydrides capable of releasing hydrogen in aqueous solutions at ambient conditions, one or more transition metal compounds are used to catalyze the reaction and, optionally, one or more alkali metal-based compounds. The metal or alloy is preferably aluminum. The inorganic hydride is from a family of complex inorganic hydrides; most preferably, NaBH.sub.4. The transition metal catalyst is from the groups VIII and IB; preferably, Cu and Fe. The alkali metal-based compounds are preferably NaOH, KOH, and the like. Hydrogen generated has a purity of at least 99.99 vol. % (dry basis), and is used without further purification in all types of fuel cells, including the polymer electrolyte membrane (PEM) fuel cell.

  7. Liquid Hydrogen Fuel System for Small Unmanned Air Vehicles (United States)


    propulsion plant comprised a hydrogen fuel cell system, built by Protonex Technology Corporation, which weighed 2.5 lbs and produced a maximum of 550... NASA for flight on long-endurance UAVs. 9 Aluminum was selected for both the inner and outer walls of the LH2 dewar because of its low H2...impact of cooling from air flow would ordinarily be tested in a wind tunnel, LH2 safety complicates indoor testing in a wind tunnel, as

  8. Modeling the process of producing hydrogen from methane


    Dubinin, A. M.; Tuponogov, V. G.; Ikonnikov, I. S.


    Using the chemical reactions that accompany the production of syngas via the steam reforming of methane as a basis, the differential material balance equations were derived and solved for all conversion products on an aluminum/nickel catalyst. For the following stage of hydrogen synthesis on an iron/chromium catalyst, the system of two differential equations of the material balance of the direct and reverse reactions of steam carbon monoxide conversion was obtained and solved. The analytical ...

  9. Elimination of abnormal combustion in a hydrogen-fueled engine

    Energy Technology Data Exchange (ETDEWEB)

    Swain, M.R.; Swain, M.N. [Analytical Technologies, Inc., Miami, FL (United States)


    This report covers the design, construction, and testing of a dedicated hydrogen-fueled engine. Both part-load and full-load data were taken under laboratory conditions. The engine design included a billet aluminum single combustion chamber cylinder-head with one intake valve, two sodium coiled exhaust valves, and two spark plugs. The cylinder-head design also included drilled cooling passages. The fuel-delivery system employed two modified Siemens electrically actuated fuel injectors, The exhaust system included two separate headers, one for each exhaust port. The piston/ring combination was designed specifically for hydrogen operation.

  10. Lead exposure from aluminum cookware in Cameroon

    Energy Technology Data Exchange (ETDEWEB)

    Weidenhamer, Jeffrey D.; Kobunski, Peter A. [Department of Chemistry, Geology and Physics, 401 College Ave., Ashland University, Ashland, OH 44805 (United States); Kuepouo, Gilbert [Research and Education Centre for Development (CREPD), Yaounde (Cameroon); Corbin, Rebecca W. [Department of Chemistry, Geology and Physics, 401 College Ave., Ashland University, Ashland, OH 44805 (United States); Gottesfeld, Perry, E-mail: [Occupational Knowledge International, San Francisco, CA (United States)


    Blood lead levels have decreased following the removal of lead from gasoline in most of the world. However, numerous recent studies provide evidence that elevated blood lead levels persist in many low and middle-income countries around the world at much higher prevalence than in the more developed countries. One potential source of lead exposure that has not been widely investigated is the leaching of lead from artisanal aluminum cookware, which is commonly used in the developing world. Twenty-nine samples of aluminum cookware and utensils manufactured by local artisans in Cameroon were collected and analyzed for their potential to release lead during cooking. Source materials for this cookware included scrap metal such as engine parts, radiators, cans, and construction materials. The lead content of this cookware is relatively low (< 1000 ppm by X-ray fluorescence), however significant amounts of lead, as well as aluminum and cadmium were released from many of the samples using dilute acetic acid extractions at boiling and ambient temperatures. Potential exposures to lead per serving were estimated to be as high as 260 μg, indicating that such cookware can pose a serious health hazard. We conclude that lead, aluminum and cadmium can migrate from this aluminum cookware during cooking and enter food at levels exceeding recommended public health guidelines. Our results support the need to regulate lead content of materials used to manufacture these pots. Artisanal aluminum cookware may be a major contributor to lead poisoning throughout the developing world. Testing of aluminum cookware in other developing countries is warranted. - Highlights: • Cookware is manufactured in Cameroon from scrap aluminum including car parts. • Twenty-nine cookware samples were evaluated for their potential to leach lead. • Boiling extractions to simulate the effects of cooking released significant lead. • Potential lead exposures per serving are estimated as high as 260 μg.

  11. Final Report: Metal Perhydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, J-Y.; Shi, S.; Hackney, S.; Swenson, D.; Hu, Y.


    H molecule contains one hydrogen atom because the valence of a Li ion is +1. One MgH2 molecule contains two hydrogen atoms because the valence of a Mg ion is +2. In metal perhydrides, a molecule could contain more hydrogen atoms than expected based on the metal valance, i.e. LiH1+n and MgH2+n (n is equal to or greater than 1). When n is sufficiently high, there will be plenty of hydrogen storage capacity to meet future requirements. The existence of hydrogen clusters, Hn+ (n = 5, 7, 9, 11, 13, 15) and transition metal ion-hydrogen clusters, M+(H2)n (n = 1-6), such as Sc(H2)n+, Co(H2)n+, etc., have assisted the development of this concept. Clusters are not stable species. However, their existence stimulates our approach on using electric charges to enhance the hydrogen adsorption in a hydrogen storage system in this study. The experimental and modeling work to verify it are reported here. Experimental work included the generation of cold hydrogen plasma through a microwave approach, synthesis of sorbent materials, design and construction of lab devices, and the determination of hydrogen adsorption capacities on various sorbent materials under various electric field potentials and various temperatures. The results consistently show that electric potential enhances the adsorption of hydrogen on sorbents. NiO, MgO, activated carbon, MOF, and MOF and platinum coated activated carbon are some of the materials studied. Enhancements up to a few hundred percents have been found. In general, the enhancement increases with the electrical potential, the pressure applied, and the temperature lowered. Theoretical modeling of the hydrogen adsorption on the sorbents under the electric potential has been investigated with the density functional theory (DFT) approach. It was found that the interaction energy between hydrogen and sorbent is increased remarkably when an electric field is applied. This increase of binding energy offers a potential solution for DOE when looking for a compromise

  12. Applications of pattern recognition in aluminum alloy texture characterization (United States)

    Liu, Guizhong; Rehbein, D. K.; Foley, James C.; Thompson, R. B.


    This paper presents a methodology to extract texture information in Aluminum alloys using pattern recognition algorithm. The orientation of the samples can be obtained by the orientation Image Microscope (OIM) technique. The ISO DATA pattern recognition algorithm is implemented to classify the OIM data into different clusters. Based on the classification results, the probability density function (pdf) is estimated. Then, the pdf is expanded as a series of Legendre functions with coefficients, i.e., the orientation distribution coefficients (ODC) as texture parameters. Three of these ODC's are of special interests, namely W400, W420, and W440. This paper includes results from ultrasonic NDE and this novel algorithm.—Ames Laboratory is operated for U.S. Department of Energy by Iowa State University under Contract W-7405-ENG-82. This work was supported by the Office of Basic Energy Sciences as a part of the Center of Excellence of the Synthesis and Processing of Advanced Materials.

  13. Positron annihilation Doppler broadening study of Xe-implanted aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yu, R.S., E-mail: [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China); Maekawa, M.; Kawasuso, A. [Japan Atomic Energy Agency, Advanced Science Research Center, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Wang, B.Y.; Wei, L. [Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, No. 19 Yuquan Lu, Beijing 100049 (China)


    Positron annihilation Doppler broadening measurements were conducted to characterize information of defects in 380 keV Xe{sup +}-implanted aluminum upon thermal annealing at temperatures ranging from 100 to 600 °C. The results suggest a broad distribution in the depth of vacancy-type defects in all the as-implanted samples. Meanwhile, with an increase in implantation dose the defect-rich region shifts toward the sample surface. It was found that increasing the annealing temperature triggers surface-directed migration and coalescence of vacancy and Xe{sub n}V{sub m} clusters in samples with implantation doses of 1E15 and 1E16 Xe{sup +}cm{sup −2}. In the sample implanted with a high dose of 1E17 Xe{sup +}cm{sup −2}, positron annihilation revealed a decomposition and even elimination of such defects under post-implantation annealing treatment.

  14. Fatigue analysis of aluminum drill pipes

    Directory of Open Access Journals (Sweden)

    João Carlos Ribeiro Plácido


    Full Text Available An experimental program was performed to investigate the fundamental fatigue mechanisms of aluminum drill pipes. Initially, the fatigue properties were determined through small-scale tests performed in an optic-mechanical fatigue apparatus. Additionally, full-scale fatigue tests were carried out with three aluminum drill pipe specimens under combined loading of cyclic bending and constant axial tension. Finally, a finite element model was developed to simulate the stress field along the aluminum drill pipe during the fatigue tests and to estimate the stress concentration factors inside the tool joints. By this way, it was possible to estimate the stress values in regions not monitored during the fatigue tests.

  15. Nanshan Aluminum Reached Strategic Cooperation with CSR Corporation Limited

    Institute of Scientific and Technical Information of China (English)


    As a key supplier of aluminum profiles and aluminum plate,sheet and trip products for CSR Corporation Limited,Nanshan Aluminum will join hands with CSR Corporation Limited to reach strategic cooperation.On January 5,Nanshan Aluminum signed strategic cooperation agreement with CSR Sifang Locomotive&Rolling; Stock Co.,Ltd,both

  16. Changes in porosity of foamed aluminum during solidification

    Institute of Scientific and Technical Information of China (English)


    In order to control the porosity of foamed aluminum, the changes in the porosity of foamed aluminum melt in the processes of foaming and solidification, the distribution of the porosity of foamed aluminum, and the relationship between them were studied. The results indicated that the porosity of foamed aluminum coincides well with the foaming time.

  17. A hydrogen ice cube

    NARCIS (Netherlands)

    Schrauwers, A.


    Hydrogen is considered to be a highly promising energy carrier. Nonetheless, before hydrogen can become the fuel of choice for the future a number of slight problems will have to be overcome. For example, how can hydrogen be safely stored? Motor vehicles running on hydrogen may be clean in concept b

  18. Electrocatalytic studies of iridium based clusters for the oxygen reduction and hydrogen oxidation reactions in 0.5 M H2SO4, in the presence of fuel cell contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Uribe-Godinez, J.; Jimenez-Sandoval, O.; Borja-Arco, E.; Altamirano-Gutierrez, A. [Centro de Investigacion y de Estudios Avanzados del Inst. Politecnico Nacional, Queretaro (Mexico); Castellanos, R.H. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-Queretaro, Queretaro (Mexico)


    The development of a cost effective cathode catalyst which is tolerant to CH3OH is a priority for the development of proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Ruthenium (Ru) and osmium nanoclusters are among the most promising alternatives to platinum (Pt) for the oxygen reduction reaction (ORR). However, iridium (Ir) is one of the most stable Pt group metals in acid media. Although it has a lower activity towards the ORR and hydrogen oxidation reaction (HOR) than platinum, its activity towards CH3OH is also lower than that of Pt. The synthetic procedure in this study was based on the pyrolysis of Ir4(CO)12 at 190 degrees C, under neutral (N2) and reductive atmospheres (H2) for 5 hours. The new materials were structurally characterized by FT-IR and micro-Raman spectroscopy, X-ray diffraction and scanning electron microscopy, and electrochemistry by the rotating disk electrode (RDE) technique in a 0.5 M H2SO4 electrolyte, at room temperature. This paper reported on the the electrokinetic parameters, such as the Tafel slope, the interchange current density and the transfer coefficient. It was concluded that the new materials are good candidates for their use as both anodes and cathodes as commercial platinum catalysts in PEMFC. All the new electrocatalysts performed the HOR, even in the presence of carbon monoxide, which is a clear advantage over Pt catalysts. 4 refs., 3 figs.

  19. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

    Institute of Scientific and Technical Information of China (English)


    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  20. Helium-tight Laser Beam Welding of Aluminum with Brillant Laser Beam Radiation (United States)

    Heinen, Paul; Wu, Hao; Olowinsky, Alexander; Gillner, Arnold

    The substitution of steel as base metal for casings and packaging applications has increased during the last years. Especially aluminum with advantages in weight and machining effort has become a versatile solution for applications in fine mechanics (e.g. sensor housings) and automotive applications. Joining of aluminum components is more critical due to possible crack formation in the joining seam and uneven seam geometry. With the high intensity of brillant laser beam sources the specific challenges of aluminum welding can be overcome. Due to its hydrogen affinity and high degree of reflection for laser radiation at a wavelength of 1 μm (95%) aluminum needs to be welded with proper shielding gas support and high beam quality in order to avoid seam defects. Cracks and pores can lead to non-sufficient tightness for sensor applications and early failure. Housing components have been joined to form a functioning unit in order to seal electrical or measuring components, which are helium-tight for these applications.

  1. Cluster chemistry in the Noughties: new developments and their relationship to nanoparticles. (United States)

    Hogarth, Graeme; Kabir, Shariff E; Nordlander, Ebbe


    Over the past decade, the chemistry of low-valent transition metal clusters has again come to the fore, primarily as a result of the development of nanochemistry and the realization that large clusters are on the cusp of the nano-domain. This perspective focuses on these recent developments in low-valent transition metal cluster chemistry, specifically looking at cluster-nanoparticles, the use of small and medium sized clusters as nanoparticle precursors, the development of clusters as homogeneous catalysts and hydrogen uptake and storage systems, together with fundamental discoveries relating to novel transformations that can take place within the cluster framework.

  2. South West Aluminum: Next year The Capacity of Auto-use Aluminum Sheet will Reach 5000 Tonnes

    Institute of Scientific and Technical Information of China (English)


    Following supplying supporting aluminum products for"Shenzhou"spacecraft,"Long March"rocket,Boeing and Airbus,South West Aluminum again tapped new economic growth points,i.e.automobile-use aluminum products.According to what the reporter has learned from South West Aluminum Group recently,this group has finished early stage

  3. Aluminum recovery as a product with high added value using aluminum hazardous waste. (United States)

    David, E; Kopac, J


    The samples of hazardous aluminum solid waste such as dross were physically and chemically characterized. A relationship between density, porosity and metal content of dross was established. The paper also examines the chemical reactions involving aluminum dross in landfill and the negative consequences. To avoid environmental problems and to recovery the aluminum, a processing method was developed and aluminum was recovered as an added value product such as alumina. This method refers to a process at low temperature, in more stages: acid leaching, purification, precipitation and calcination. At the end of this process aluminum was extracted, first as Al(3+) soluble ions and final as alumina product. The composition of the aluminum dross and alumina powder obtained were measured by applying the leaching tests, using atomic absorption spectrometry (AAS) and chemical analysis. The mineralogical composition of aluminum dross samples and alumina product were determined by X-ray diffraction (XRD) and the morphological characterization was performed by scanning electron microscopy (SEM). The method presented in this work allows the use of hazardous aluminum solid waste as raw material to recover an important fraction from soluble aluminum content as an added value product, alumina, with high grade purity (99.28%).

  4. Preliminary Study on Aluminum Content of Foods and Aluminum Intake of Residents in Tianjin

    Institute of Scientific and Technical Information of China (English)

    XUGe-Sheng; JINRng-Pei; 等


    Aluminum contents of 64 kinds of foods in Tianjin were detrmined.The results showed that the aluminum levels in diffeent kinds of foods varied greatly,and most foodstuffs from natural sources(including contamination from food processing)contained less than 10mg/kg,Aluminum contents were higher in foodstuffs of plant origin,especiallydry beans containing large amounts of aluminum naturally.Lower concentration of aluminum seemed to be present in foodstuffs of animal origin.It was estimated that the potential daily intake of aluminum per person from natural dietary sources in Tianjin was about 3.79 mg.This estimated figure of dietary aluminum intake was very close to the measured data from 24 daily diets of college students.which was 4.86±1.72mg.Considering all the potential sources of natural aluminum in foods.water and the individual habitual food,it would apear that most residents in Tianjin would consume 3-10mg aluminum daily from natural dietary sources.

  5. Southwest Aluminum Increase Two Production Lines and May Become the Largest Aluminum Fabricator In the World

    Institute of Scientific and Technical Information of China (English)


    <正>Recently,Wu Bing,Director of Chongqing Economic Committee,announced at the"Industrial Economy Meeting"that the city will"facilitate the technical upgrade and capacity expansion of the existing production lines at Southwest Aluminum with great efforts on the construction of one additional hot continuous rolling line and one cold continuous rolling line so as to have a comprehensive production ca- pacity of 1.2 million tons on aluminum processing profiles for the achievement of building Southwest Aluminum into the world largest aluminum processing enterprise".

  6. Over-heated Investment in Aluminum Hub Industry

    Institute of Scientific and Technical Information of China (English)


    <正>Aluminum hub is one of typical products with the comparative advantages.China’s aluminum hub industry is very competitive.In recent years,the value of export for the aluminum hub soared,increasing from USD130 millions in 1999 up to nearly USD1 billion in 2004.The main exporter are Wanfeng Auto Holding Group,Shanghai Fervent Alloy Wheel MFG Co.,Ltd.,Nanhai Zhongnan Aluminum Co., Ltd.,Taian Huatai Aluminum Hub Co.,Ltd.

  7. Comparative study of hydrogenated and lithiated superhalogens (United States)

    Xu, Li-Na; Li, Ying; Liu, Jia-Yuan; Wu, Di; Sun, Yan-Bo; Li, Zhi-Ru


    The structural features, properties and stability of two kinds of representative superhalogen compounds, namely hydrogenated superhalogens and lithiated superhalogens, are theoretically studied in detail, providing further insight into the behavior of superhalogens. According to topological analysis of the electron localization function, most of superhalogen clusters as a whole combine with Li atom through ionic bond(s). In contrast, the H atom tends to bind with superhalogen by covalent bond although a portion of superhalogens are broken upon hydrogenation. In addition, the electric properties of these superhalogen compounds are also obtained and compared with those of traditional acid and salt molecules.

  8. Aluminum-CNF Lightweight Radiator Components Project (United States)

    National Aeronautics and Space Administration — This proposal relates to a new materials concept for an aluminum-carbon nanofiber composite, high thermal conductivity ultra lightweight material that will form the...

  9. Profit of Aluminum Industry Dropped Sharply

    Institute of Scientific and Technical Information of China (English)


    <正>On August 2nd,the Ministry of Industry and Information Technology published the performance of nonferrous metal industry in the first half of 2011.Relevant data showed that due to cost increase,aluminum smelting enter

  10. Aluminum plasmonic multicolor meta-hologram. (United States)

    Huang, Yao-Wei; Chen, Wei Ting; Tsai, Wei-Yi; Wu, Pin Chieh; Wang, Chih-Ming; Sun, Greg; Tsai, Din Ping


    We report a phase-modulated multicolor meta-hologram (MCMH) that is polarization-dependent and capable of producing images in three primary colors. The MCMH structure is made of aluminum nanorods that are arranged in a two-dimensional array of pixels with surface plasmon resonances in red, green, and blue. The aluminum nanorod array is patterned on a 30 nm thick SiO2 spacer layer sputtered on top of a 130 nm thick aluminum mirror. With proper design of the structure, we obtain resonances of narrow bandwidths to allow for implementation of the multicolor scheme. Taking into account of the wavelength dependence of the diffraction angle, we can project images to specific locations with predetermined size and order. With tuning of aluminum nanorod size, we demonstrate that the image color can be continuously varied across the visible spectrum.

  11. Masking of aluminum surface against anodizing (United States)

    Crawford, G. B.; Thompson, R. E.


    Masking material and a thickening agent preserve limited unanodized areas when aluminum surfaces are anodized with chromic acid. For protection of large areas it combines well with a certain self-adhesive plastic tape.

  12. Shock wave compression behavior of aluminum foam

    Institute of Scientific and Technical Information of China (English)

    程和法; 黄笑梅; 薛国宪; 韩福生


    The shock wave compression behavior of the open cell aluminum foam with relative density of 0. 396 was studied through planar impact experiments. Using polyvinylidene fluoride(PVDF) piezoelectric gauge technique, the stress histories and propagation velocities of shock wave in the aluminum foam were measured and analyzed. The results show that the amplitude of shock wave attenuates rapidly with increasing the propagation distance in the aluminum foam, and an exponential equation of the normalized peak stress vs propagation distance of shock wave is established, the attenuation factor in the equation is 0. 286. Furthermore, the Hugoniot relation, νs = 516.85+ 1.27νp,for the aluminum foam is determined by empirical fit to the experimental Hugoniot data.

  13. China Aluminum Processing Industry Development Report 2011

    Institute of Scientific and Technical Information of China (English)


    <正>In 2011,China’s aluminum processing industry maintained a high growth rate,with the aluminum output reaching 23,456,000tons,up 20.6% y-o-y.Overshadowed by complicated situation both at home and abroad,China’seconomy slowed down and declined by2.2% y-o-y.In 2011,China’s aluminum processing industry showed a downward tendency,that is,it grew at a high speed before the3rd quarter,but suffered from a shortage of orders in the remaining time of the year and the growth rate fell increasingly.Between January and August,China’s aluminum output rose by 26% y-o-y;

  14. Cluster headache

    Directory of Open Access Journals (Sweden)

    Ducros Anne


    Full Text Available Abstract Cluster headache (CH is a primary headache disease characterized by recurrent short-lasting attacks (15 to 180 minutes of excruciating unilateral periorbital pain accompanied by ipsilateral autonomic signs (lacrimation, nasal congestion, ptosis, miosis, lid edema, redness of the eye. It affects young adults, predominantly males. Prevalence is estimated at 0.5–1.0/1,000. CH has a circannual and circadian periodicity, attacks being clustered (hence the name in bouts that can occur during specific months of the year. Alcohol is the only dietary trigger of CH, strong odors (mainly solvents and cigarette smoke and napping may also trigger CH attacks. During bouts, attacks may happen at precise hours, especially during the night. During the attacks, patients tend to be restless. CH may be episodic or chronic, depending on the presence of remission periods. CH is associated with trigeminovascular activation and neuroendocrine and vegetative disturbances, however, the precise cautive mechanisms remain unknown. Involvement of the hypothalamus (a structure regulating endocrine function and sleep-wake rhythms has been confirmed, explaining, at least in part, the cyclic aspects of CH. The disease is familial in about 10% of cases. Genetic factors play a role in CH susceptibility, and a causative role has been suggested for the hypocretin receptor gene. Diagnosis is clinical. Differential diagnoses include other primary headache diseases such as migraine, paroxysmal hemicrania and SUNCT syndrome. At present, there is no curative treatment. There are efficient treatments to shorten the painful attacks (acute treatments and to reduce the number of daily attacks (prophylactic treatments. Acute treatment is based on subcutaneous administration of sumatriptan and high-flow oxygen. Verapamil, lithium, methysergide, prednisone, greater occipital nerve blocks and topiramate may be used for prophylaxis. In refractory cases, deep-brain stimulation of the

  15. Advances in molecular vibrations and collision dynamics molecular clusters

    CERN Document Server

    Bacic, Zatko


    This volume focuses on molecular clusters, bound by van der Waals interactions and hydrogen bonds. Twelve chapters review a wide range of recent theoretical and experimental advances in the areas of cluster vibrations, spectroscopy, and reaction dynamics. The authors are leading experts, who have made significant contributions to these topics.The first chapter describes exciting results and new insights in the solvent effects on the short-time photo fragmentation dynamics of small molecules, obtained by combining heteroclusters with femtosecond laser excitation. The second is on theoretical work on effects of single solvent (argon) atom on the photodissociation dynamics of the solute H2O molecule. The next two chapters cover experimental and theoretical aspects of the energetics and vibrations of small clusters. Chapter 5 describes diffusion quantum Monte Carlo calculations and non additive three-body potential terms in molecular clusters. The next six chapters deal with hydrogen-bonded clusters, refle...

  16. Oxidation of olefins with H2O2 catalyzed by gallium(III) nitrate and aluminum(III) nitrate in solution

    NARCIS (Netherlands)

    Mandelli, Dalmo; Kozlov, Yuriy N.; da Silva, Cezar A R; Carvalho, Wagner A.; Pescarmona, Paolo P.; Cella, Daniele de A; de Paiva, Polyana T.; Shul'pin, Georgiy B.


    Soluble gallium and aluminum nitrates (simple salts of non-transition metals) are good catalysts for the epoxidation of olefins (cyclooctene, dec-1-ene) including terpenes (carvone, limonene) with hydrogen peroxide in ethyl acetate or tetrahydrofurane (THF). Typically, the gallium salt is more effic

  17. Advanced powder metallurgy aluminum alloys and composites (United States)

    Lisagor, W. B.; Stein, B. A.


    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  18. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.


    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T(e and N(e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T(e and N(e for the aluminum in aluminum alloys using an optical fiber probe.

  19. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.


    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  20. Transfer and transport of aluminum in filtration unit

    Institute of Scientific and Technical Information of China (English)


    Aluminum salt coagulants were used prevalently in various water works. In this article, the effects of filtration on residual aluminum concentration and species distribution were researched by determining the concentration of different Aluminum species before and after single layer filter, double layer filter, and membrane filtration units. In the research, size exclusion chromatography (SEC) was used to separate colloidal and soluble aluminum, ion exchange chromatography (IEC) was used to separate organic and inorganic aluminum, and inductivity coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine the aluminum concentration. The results showed that the rapid filtration process had the ability of removing residual aluminum from coagulant effluent water, and that double layer filtration was more effective in residual aluminum removal than single layer filtration, while Nano filtration was more effective than micro filtration. It was found that when the residual aluminum concentration was below 1mg/L in sediment effluent, the residual aluminum concentration in treated water was above 0.2 mg/L. The direct rapid filtration process mainly removed the suspended aluminum. The removal of soluble and colloidal aluminum was always less than 10% and the natural small particles that adsorbed the amount of soluble or small particles aluminum on their surface were difficult to be removed in this process. Micro filtration and nano filtration were good technologies for removing aluminum; the residual aluminum concentration in the effluent was less than 0.05 mg/L.

  1. Molecular Cluster Perturbation Theory. I. Formalism

    CERN Document Server

    Byrd, Jason N; Molt,, Robert W; Bartlett, Rodney J; Sanders, Beverly A; Lotrich, Victor F


    We present second-order molecular cluster perturbation theory (MCPT(2)), a methodology to calculate arbitrarily large systems with explicit calculation of individual wavefunctions in a coupled cluster framework. This new MCPT(2) framework uses coupled cluster perturbation theory and an expansion in terms of molecular dimer interactions to obtain molecular wavefunctions that are infinite order in both the electronic fluctuation operator and all possible dimer (and products of dimers) interactions. The MCPT(2) framework has been implemented in the new SIA/ACES parallel architecture, making use of the advanced dynamic memory control and fine grained parallelism to perform very large explicit molecular cluster calculations. To illustrate the power of this method, we have computed energy shifts and lattice site dipole moments for the polar and non-polar configurations of solid hydrogen fluoride by scaling an explicit lattice to the bulk limit. The explicit lattice size without periodic boundary conditions was scal...

  2. Why hydrogen; Pourquoi l'hydrogene?

    Energy Technology Data Exchange (ETDEWEB)



    The energy consumption increase and the associated environmental risks, led to develop new energy sources. The authors present the potentialities of the hydrogen in this context of energy supply safety. They detail the today market and the perspectives, the energy sources for the hydrogen production (fossils, nuclear and renewable), the hydrogen transport, storage, distribution and conversion, the application domains, the associated risks. (A.L.B.)

  3. Studies of aluminum in rat brain

    Energy Technology Data Exchange (ETDEWEB)

    Lipman, J.J.; Brill, A.B.; Som, P.; Jones, K.W.; Colowick, S.; Cholewa, M.


    The effects of high aluminum concentrations in rat brains were studied using /sup 14/C autoradiography to measure the uptake of /sup 14/C 2-deoxy-D-glucose (/sup 14/C-2DG) and microbeam proton-induced x-ray emission (microPIXE) with a resolution to measure concentrations of magnesium, aluminum, potassium, and calcium. The aluminum was introduced intracisternally in the form of aluminum tartrate (Al-T) while control animals were given sodium tartrate (Na-T). The /sup 14/C was administered intravenously. The animals receiving Al-T developed seizure disorders and had pathological changes that included cerebral cortical atrophy. The results showed that there was a decreased uptake of /sup 14/C-2DG in cortical regions in which increased aluminum levels were measured, i.e., there is a correlation between the aluminum in the rat brain and decreased brain glucose metabolism. A minimum detection limit of about 16 ppM (mass fraction) or 3 x 10/sup 9/ Al atoms was obtained for Al under the conditions employed. 14 refs., 4 figs., 1 tab.

  4. Theoretical analysis of hydrogen spillover mechanism on carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Rosalba eJuarez Mosqueda


    Full Text Available The spillover mechanism of molecular hydrogen on carbon nanotubes in the presence of catalytically active platinum clusters was critically and systematically investigated by using density-functional theory. Our simulation model includes a Pt4 cluster for the catalyst nanoparticle and curved and planar circumcoronene for two exemplary single-walled carbon nanotubes (CNT, the (10,10 CNT and one of large diameter, respectively. Our results show that the H2 molecule dissociates spontaneously on the Pt4 cluster. However, the dissociated H atoms have to overcome a barrier of more than 2 eV to migrate from the catalyst to the CNT, even if the Pt4 cluster is at full saturation with six adsorbed and dissociated hydrogen molecules. Previous investigations have shown that the mobility of hydrogen atoms on the CNT surface is hindered by a barrier. We find that instead the Pt4 catalyst may move along the outer surface of the CNT with activation energy of only 0.16 eV, and that this effect offers the possibility of full hydrogenation of the CNT. Thus, although we have not found a low-energy pathway to spillover onto the CNT, we suggest, based on our calculations and calculated data reported in the literature, that in the hydrogen-spillover process the observed saturation of the CNT at hydrogen background pressure occurs through mobile Pt nanoclusters, which move on the substrate more easily than the substrate-chemisorbed hydrogens, and deposit or reattach hydrogens in the process. Initial hydrogenation of the carbon substrate, however, is thermodynamically unfavoured, suggesting that defects should play a significant role.

  5. Partitional clustering algorithms

    CERN Document Server


    This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

  6. Determination of the Relative Atomic Masses of Metals by Liberation of Molecular Hydrogen (United States)

    Waghorne, W. Earle; Rous, Andrew J.


    Students determine the relative atomic masses of calcium, magnesium, and aluminum by reaction with hydrochloric acid and measurement of the volume of hydrogen gas liberated. The experiment demonstrates stoichiometry and illustrates clearly that mass of the reagent is not the determinant of the amounts in chemical reactions. The experiment is…

  7. Clustering and Community Detection with Imbalanced Clusters


    Aksoylar, Cem; Qian, Jing; Saligrama, Venkatesh


    Spectral clustering methods which are frequently used in clustering and community detection applications are sensitive to the specific graph constructions particularly when imbalanced clusters are present. We show that ratio cut (RCut) or normalized cut (NCut) objectives are not tailored to imbalanced cluster sizes since they tend to emphasize cut sizes over cut values. We propose a graph partitioning problem that seeks minimum cut partitions under minimum size constraints on partitions to de...

  8. Time exposure studies on stress corrosion cracking of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651, and titanium 6Al-4V (United States)

    Terrell, J.


    The effect of a constant applied stress in crack initiation of aluminum 2014-T6, 2219-T87, 2014-T651, 7075-T651 and titanium 6Al-4V has been investigated. Aluminum c-ring specimens (1-inch diameter) and u-band titanium samples were exposed continuously to a 3.5% NaCl solution (pH 7) and organic fluids of ethyl, methyl, and iso-propyl alcohol (reagent purity), and demineralized distilled water. Corrosive action was observed to begin during the first and second day of constant exposure as evidenced by accumulation of hydrogen bubbles on the surface of stressed aluminum samples. However, titanium stressed specimens showed no reactions to its environment. Results of this investigation seems to suggest that aluminum 2014-T6, aluminum 7075-T651 and aluminum 2014-T651 are susceptible to stress corrosion cracking in chloride solution (NaCl), while aluminum 2219-T87 seem to resist stress corrosion cracking in sodium chloride at three levels of stress (25%, 50%, and 75% Y.S.). In organic fluids of methyl, ethyl, and iso-propyl alcohol, 2014-T6 and 7075-T651 did not fail by SCC; but 2014-T651 was susceptible to SCC in methly alcohol, but resistant in ethyl alcohol, iso-propyl alcohol and demineralized distilled water.

  9. Cryogenic hydrogen-induced air-liquefaction technologies (United States)

    Escher, William J. D.


    Extensive use of a special advanced airbreathing propulsion archives data base, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented in 1986. The resulting assessment report is summarized. Technical findings relating the status of air liquefaction technology are presented both as a singular technical area, and also as that of a cluster of collateral technical areas including: Compact lightweight cryogenic heat exchangers; Heat exchanger atmospheric constituents fouling alleviation; Para/ortho hydrogen shift conversion catalysts; Hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; Hydrogen recycling using slush hydrogen as heat sinks; Liquid hydrogen/liquid air rocket type combustion devices; Air Collection and Enrichment System (ACES); and Technically related engine concepts.

  10. Iron-aluminum alloys having high room-temperature and method for making same (United States)

    Sikka, V.K.; McKamey, C.G.


    A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

  11. Nanostructures Using Anodic Aluminum Oxide (United States)

    Valmianski, Ilya; Monton, Carlos M.; Pereiro, Juan; Basaran, Ali C.; Schuller, Ivan K.


    We present two fabrication methods for asymmetric mesoscopic dot arrays over macroscopic areas using anodic aluminum oxide templates. In the first approach, metal is deposited at 45o to the template axis to partially close the pores and produce an elliptical shadow-mask. In the second approach, now underway, nanoimprint lithography on a polymer intermediary layer is followed by reactive ion etching to generate asymmetric pore seeds. Both these techniques are quantified by an analysis of the lateral morphology and lattice of the pores or dots using scanning electron microscopy and a newly developed MATLAB based code (available for free download at The code automatically provides a segmentation of the measured area and the statistics of morphological properties such as area, diameter, and eccentricity, as well as the lattice properties such as number of nearest neighbors, and unbiased angular and radial two point correlation functions. Furthermore, novel user defined statistics can be easily obtained. We will additionally present several applications of these methods to superconducting, ferromagnetic, and organic nanostructures. This work is supported by AFOSR FA9550-10-1-0409

  12. Hydrogen energy systems studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, J.M.; Kreutz, T.G.; Steinbugler, M. [Princeton Univ., NJ (United States)] [and others


    In this report the authors describe results from technical and economic assessments carried out during the past year with support from the USDOE Hydrogen R&D Program. (1) Assessment of technologies for small scale production of hydrogen from natural gas. Because of the cost and logistics of transporting and storing hydrogen, it may be preferable to produce hydrogen at the point of use from more readily available energy carriers such as natural gas or electricity. In this task the authors assess near term technologies for producing hydrogen from natural gas at small scale including steam reforming, partial oxidation and autothermal reforming. (2) Case study of developing a hydrogen vehicle refueling infrastructure in Southern California. Many analysts suggest that the first widespread use of hydrogen energy is likely to be in zero emission vehicles in Southern California. Several hundred thousand zero emission automobiles are projected for the Los Angeles Basin alone by 2010, if mandated levels are implemented. Assuming that hydrogen vehicles capture a significant fraction of this market, a large demand for hydrogen fuel could evolve over the next few decades. Refueling a large number of hydrogen vehicles poses significant challenges. In this task the authors assess near term options for producing and delivering gaseous hydrogen transportation fuel to users in Southern California including: (1) hydrogen produced from natural gas in a large, centralized steam reforming plant, and delivered to refueling stations via liquid hydrogen truck or small scale hydrogen gas pipeline, (2) hydrogen produced at the refueling station via small scale steam reforming of natural gas, (3) hydrogen produced via small scale electrolysis at the refueling station, and (4) hydrogen from low cost chemical industry sources (e.g. excess capacity in refineries which have recently upgraded their hydrogen production capacity, etc.).

  13. Simultaneous determination of trace iron and aluminum by catalytic spectrophotometry based on a novel oxidation reaction of xylene cyanol FF. (United States)

    Cai, Longfei; Xu, Chunxiu


    A new, simple, sensitive and selective method for the simultaneous determination of trace iron and aluminum by catalytic spectrophotometry was presented, based on the catalytic effects of iron and aluminum on the discoloring reaction of xylene cyanol FF proceeded by hydrogen peroxide and potassium periodate in weak nitric acid medium. No catalytic effect was obtained in the presence of hydrogen peroxide or potassium periodate only. With the conditional rate constants determined in reaction systems catalyzed by Al or Fe only, the concentrations of Fe and Al in the samples can be calculated. The method was applied to the simultaneous determination of trace Fe and Al in tap water, lake water, river water and tea leaves without separation and preconcentration.

  14. Cluster headaches. (United States)

    Ryan, R E; Ryan, R E


    The patient with cluster headaches will be afflicted with the most severe type of pain that one will encounter. If the physician can do something to help this patient either by symptomatic or, more importantly, prophylactic treatment, he or she will have a most thankful patient. This type of headache is seen most frequently in men, and occurs in a cyclic manner. During an acute cycle, the patient will experience a daily type of pain that may occur many times per day. The pain is usually unilateral and may be accompanied by unilateral lacrimation, conjunctivitis, and clear rhinorrhea. Prednisone is the first treatment we employ. Patients are seen for follow-up approximately twice a week, and their medication is lowered in an appropriate manner, depending on their response to the treatment. Regulation of dosage has to be individualized, and when one reaches the lower dose such as 5 to 10 mg per day, the drug may have to be tapered more slowly, or even maintained at that level for a period of time to prevent further recurrence of symptoms. We frequently will use an intravenous histamine desensitization technique to prevent further attacks. We will give the patient an ergotamine preparation to use for symptomatic relief. As these patients often have headaches during the middle of the night, we will place the patient on a 2-mg ergotamine preparation to take prior to going to bed in the evening. This often works in a prophylactic nature, and prevents the nighttime occurrence of a headache. We believe that following these principles to make the accurate diagnosis and institute the proper therapy will help the practicing otolaryngologist recognize and treat patients suffering from this severe pain.

  15. Hydrogen in semiconductors

    CERN Document Server

    Pankove, Jacques I


    Hydrogen plays an important role in silicon technology, having a profound effect on a wide range of properties. Thus, the study of hydrogen in semiconductors has received much attention from an interdisciplinary assortment of researchers. This sixteen-chapter volume provides a comprehensive review of the field, including a discussion of hydrogenation methods, the use of hydrogen to passivate defects, the use of hydrogen to neutralize deep levels, shallow acceptors and shallow donors in silicon, vibrational spectroscopy, and hydrogen-induced defects in silicon. In addition to this detailed cove

  16. Concentration of Hydrogen Peroxide (United States)

    Parrish, Clyde F. (Inventor)


    Methods for concentrating hydrogen peroxide solutions have been described. The methods utilize a polymeric membrane separating a hydrogen peroxide solution from a sweep gas or permeate. The membrane is selective to the permeability of water over the permeability of hydrogen peroxide, thereby facilitating the concentration of the hydrogen peroxide solution through the transport of water through the membrane to the permeate. By utilizing methods in accordance with the invention, hydrogen peroxide solutions of up to 85% by volume or higher may be generated at a point of use without storing substantial quantities of the highly concentrated solutions and without requiring temperatures that would produce explosive mixtures of hydrogen peroxide vapors.

  17. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics (United States)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki


    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  18. The IMF of Globular Clusters (United States)

    De Marchi, G.; Paresce, F.


    Accurate luminosity functions (LF) for a dozen globular clusters have now been measured at or just beyond their half-light radius using HST. They span almost the entire cluster main sequence below 0.75 MO. All these clusters exhibit LF that rise continuously from an absolute I magnitude MI 6 to a peak at MI 8.5-9 and then drop with increasing MI. Transformation of the LF into mass functions (MF) by means of the most recent mass luminosity relations that are consistent with all presently available data on the physical properties of low mass, low metallicity stars shows that all the LF observed so far can be obtained from MF having the shape of a log-normal distribution with characteristic mass mc=0.33 +/- 0.03 MO and standard deviation sigma =1.81 +/- 0.19. In particular, the LF of the four clusters in the sample that extend well beyond the peak luminosity down to close to the Hydrogen burning limit (NGC6341, NGC6397, NGC6752, and NGC6809) can only be reproduced by such distributions and not by a single power-law in the 0.1 - 0.6 MO range. After correction for the effects of mass segregation, the variation of the ratio of the number of higher to lower mass stars with cluster mass or any simple orbital parameter or the expected time to disruption recently computed for these clusters shows no statistically significant trend over a range of this last parameter of more than a factor of 100. We conclude that the global MF of these clusters have not been measurably modified by evaporation and tidal interactions with the Galaxy and, thus, should reflect the initial distribution of stellar masses. Since the log-normal function that we find is also very similar to the one obtained independently for much younger clusters and to the form expected theoretically, the implication seems to be unavoidable that it represents the true stellar IMF for this type of stars in this mass range.

  19. Pore structure and mechanical properties of directionally solidified porous aluminum alloys

    Directory of Open Access Journals (Sweden)

    Komissarchuk Olga


    Full Text Available Porous aluminum alloys produced by the metal-gas eutectic method or GASAR process need to be performed under a certain pressure of hydrogen, and to carry over melt to a tailor-made apparatus that ensures directional solidification. Hydrogen is driven out of the melt, and then the quasi-cylindrical pores normal to the solidification front are usually formed. In the research, the effects of processing parameters (saturation pressure, solidification pressure, temperature, and holding time on the pore structure and porosity of porous aluminum alloys were analyzed. The mechanical properties of Al-Mg alloys were studied by the compressive tests, and the advantages of the porous structure were indicated. By using the GASAR method, pure aluminum, Al-3wt.%Mg, Al-6wt.%Mg and Al-35wt.%Mg alloys with oriented pores have been successfully produced under processing conditions of varying gas pressure, and the relationship between the final pore structure and the solidification pressure, as well as the influences of Mg quantity on the pore size, porosity and mechanical properties of Al-Mg alloy were investigated. The results show that a higher pressure of solidification tends to yield smaller pores in aluminum and its alloys. In the case of Al-Mg alloys, it was proved that with the increasing of Mg amount, the mechanical properties of the alloys sharply deteriorate. However, since Al-3%Mg and Al-6wt.%Mg alloys are ductile metals, their porous samples have greater compressive strength than that of the dense samples due to the existence of pores. It gives the opportunity to use them in industry at the same conditions as dense alloys with savings in weight and material consumption.

  20. Anodized aluminum on LDEF: A current status of measurements on chromic acid anodized aluminum (United States)

    Golden, Johnny L.


    Chromic acid anodize was used as the exterior coating for aluminum surfaces on LDEF to provide passive thermal control. Chromic acid anodized aluminum was also used as test specimens in thermal control coatings experiments. The following is a compilation and analysis of the data obtained thus far.

  1. Deposition of aluminum-magnesium alloys from electrolytes containing organo-aluminum complexes

    Energy Technology Data Exchange (ETDEWEB)

    Lehmkuhl, H.; Mehler, K.; Bongard, H.; Tesche, B. [Max-Planck-Inst. fuer Kohlenforschung, Muelheim an der Ruhr (Germany); Reinhold, B. [Audi AG Technische Entwicklung, Ingolstadt (Germany)


    Organo-aluminum compounds have been used for many years as electrolytes in the coating industry. In this communication the development of a galvanic process for generating aluminum-magnesium coatings from organometallic electrolyte systems is reported as well as results on physical properties like adhesion, ductility and corrosion resistance. (orig.)

  2. Factorial PD-Clustering

    CERN Document Server

    Tortora, Cristina; Summa, Mireille Gettler


    Factorial clustering methods have been developed in recent years thanks to the improving of computational power. These methods perform a linear transformation of data and a clustering on transformed data optimizing a common criterion. Factorial PD-clustering is based on Probabilistic Distance clustering (PD-clustering). PD-clustering is an iterative, distribution free, probabilistic, clustering method. Factorial PD-clustering make a linear transformation of original variables into a reduced number of orthogonal ones using a common criterion with PD-Clustering. It is demonstrated that Tucker 3 decomposition allows to obtain this transformation. Factorial PD-clustering makes alternatively a Tucker 3 decomposition and a PD-clustering on transformed data until convergence. This method could significantly improve the algorithm performance and allows to work with large dataset, to improve the stability and the robustness of the method.

  3. Polarization properties of real aluminum mirrors; I. Influence of the aluminum oxide layer

    CERN Document Server

    van Harten, G; Keller, C U


    In polarimetry it is important to characterize the polarization properties of the instrument itself to disentangle real astrophysical signals from instrumental effects. This article deals with the accurate measurement and modeling of the polarization properties of real aluminum mirrors, as used in astronomical telescopes. Main goals are the characterization of the aluminum oxide layer thickness at different times after evaporation and its influence on the polarization properties of the mirror. The full polarization properties of an aluminum mirror are measured with Mueller matrix ellipsometry at different incidence angles and wavelengths. The best fit of theoretical Mueller matrices to all measurements simultaneously is obtained by taking into account a model of bulk aluminum with a thin aluminum oxide film on top of it. Full Mueller matrix measurements of a mirror are obtained with an absolute accuracy of ~1% after calibration. The determined layer thicknesses indicate logarithmic growth in the first few hou...

  4. Progress in Aluminum Electrolysis Control and Future Direction for Smart Aluminum Electrolysis Plant (United States)

    Zhang, Hongliang; Li, Tianshuang; Li, Jie; Yang, Shuai; Zou, Zhong


    The industrial aluminum reduction cell is an electrochemistry reactor that operates under high temperatures and highly corrosive conditions. However, these conditions have restricted the measurement of key control parameters, making the control of aluminum reduction cells a difficult problem in the industry. Because aluminum electrolysis control systems have a significant economic influence, substantial research has been conducted on control algorithms, control systems and information systems for aluminum reduction cells. This article first summarizes the development of control systems and then focuses on the progress made since 2000, including alumina concentration control, temperature control and electrolyte molecular ratio control, fault diagnosis, cell condition prediction and control system expansion. Based on these studies, the concept of a smart aluminum electrolysis plant is proposed. The frame construction, key problems and current progress are introduced. Finally, several future directions are discussed.

  5. Methods for both coating a substrate with aluminum oxide and infusing the substrate with elemental aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jung-Pyung; Weil, Kenneth Scott


    Methods of aluminizing the surface of a metal substrate. The methods of the present invention do not require establishment of a vacuum or a reducing atmosphere, as is typically necessary. Accordingly, aluminization can occur in the presence of oxygen, which greatly simplifies and reduces processing costs by allowing deposition of the aluminum coating to be performed, for example, in air. Embodiments of the present invention can be characterized by applying a slurry that includes a binder and powder granules containing aluminum to the metal substrate surface. Then, in a combined step, a portion of the aluminum is diffused into the substrate and a portion of the aluminum is oxidized by heating the slurry to a temperature greater than the melting point of the aluminum in an oxygen-containing atmosphere.

  6. Possibilistic Exponential Fuzzy Clustering

    Institute of Scientific and Technical Information of China (English)

    Kiatichai Treerattanapitak; Chuleerat Jaruskulchai


    Generally,abnormal points (noise and outliers) cause cluster analysis to produce low accuracy especially in fuzzy clustering.These data not only stay in clusters but also deviate the centroids from their true positions.Traditional fuzzy clustering like Fuzzy C-Means (FCM) always assigns data to all clusters which is not reasonable in some circumstances.By reformulating objective function in exponential equation,the algorithm aggressively selects data into the clusters.However noisy data and outliers cannot be properly handled by clustering process therefore they are forced to be included in a cluster because of a general probabilistic constraint that the sum of the membership degrees across all clusters is one.In order to improve this weakness,possibilistic approach relaxes this condition to improve membership assignment.Nevertheless,possibilistic clustering algorithms generally suffer from coincident clusters because their membership equations ignore the distance to other clusters.Although there are some possibilistic clustering approaches that do not generate coincident clusters,most of them require the right combination of multiple parameters for the algorithms to work.In this paper,we theoretically study Possibilistic Exponential Fuzzy Clustering (PXFCM) that integrates possibilistic approach with exponential fuzzy clustering.PXFCM has only one parameter and not only partitions the data but also filters noisy data or detects them as outliers.The comprehensive experiments show that PXFCM produces high accuracy in both clustering results and outlier detection without generating coincident problems.

  7. Dynamics of hydrogen in hydrogenated amorphous silicon

    Indian Academy of Sciences (India)

    Ranber Singh; S Prakash


    The problem of hydrogen diffusion in hydrogenated amorphous silicon (a-Si:H) is studied semiclassically. It is found that the local hydrogen concentration fluctuations-induced extra potential wells, if intense enough, lead to the localized electronic states in a-Si:H. These localized states are metastable. The trapping of electrons and holes in these states leads to the electrical degradation of the material. These states also act as recombination centers for photo-generated carriers (electrons and holes) which in turn may excite a hydrogen atom from a nearby Si–H bond and breaks the weak (strained) Si–Si bond thereby apparently enhancing the hydrogen diffusion and increasing the light-induced dangling bonds.

  8. Oxidation kinetics of aluminum diboride

    Energy Technology Data Exchange (ETDEWEB)

    Whittaker, Michael L., E-mail: [Department of Materials Science and Engineering, University of Utah, 122S. Central Campus Drive, Salt Lake City, UT 84112 (United States); Sohn, H.Y. [Department of Metallurgical Engineering, University of Utah, 135S 1460 E, Rm 00412, Salt Lake City, UT 84112 (United States); Cutler, Raymond A. [Ceramatec, Inc., 2425S. 900W., Salt Lake City, UT 84119 (United States)


    The oxidation characteristics of aluminum diboride (AlB{sub 2}) and a physical mixture of its constituent elements (Al+2B) were studied in dry air and pure oxygen using thermal gravimetric analysis to obtain non-mechanistic kinetic parameters. Heating in air at a constant linear heating rate of 10 °C/min showed a marked difference between Al+2B and AlB{sub 2} in the onset of oxidation and final conversion fraction, with AlB{sub 2} beginning to oxidize at higher temperatures but reaching nearly complete conversion by 1500 °C. Kinetic parameters were obtained in both air and oxygen using a model-free isothermal method at temperatures between 500 and 1000 °C. Activation energies were found to decrease, in general, with increasing conversion for AlB{sub 2} and Al+2B in both air and oxygen. AlB{sub 2} exhibited O{sub 2}-pressure-independent oxidation behavior at low conversions, while the activation energies of Al+2B were higher in O{sub 2} than in air. Differences in the composition and morphology between oxidized Al+2B and AlB{sub 2} suggested that Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} interactions slowed Al+2B oxidation by converting Al{sub 2}O{sub 3} on aluminum particles into a Al{sub 4}B{sub 2}O{sub 9} shell, while the same Al{sub 4}B{sub 2}O{sub 9} developed a needle-like morphology in AlB{sub 2} that reduced oxygen diffusion distances and increased conversion. The model-free kinetic analysis was critical for interpreting the complex, multistep oxidation behavior for which a single mechanism could not be assigned. At low temperatures, moisture increased the oxidation rate of Al+2B and AlB{sub 2}, but both appear to be resistant to oxidation in cool, dry environments. - Graphical abstract: Isothermal kinetic data for AlB{sub 2} in air, showing a constantly decreasing activation energy with increasing conversion. Model-free analysis allowed for the calculation of global kinetic parameters despite many simultaneous mechanisms occurring concurrently. (a) Time

  9. Wastewater sludge dewaterability enhancement using hydroxyl aluminum conditioning: Role of aluminum speciation. (United States)

    Cao, Bingdi; Zhang, Weijun; Wang, Qiandi; Huang, Yangrui; Meng, Chenrui; Wang, Dongsheng


    Chemical conditioning is one of the most important processes for improve the performance of sludge dewatering device. Aluminum salt coagulant has been widely used in wastewater and sludge treatment. It is generally accepted that pre-formed speciation of aluminum salt coagulants (ASC) has an important influence on coagulation/flocculation performance. In this study, the interaction mechanisms between sludge particles and aluminum salt coagulants with different speciation of hydroxy aluminum were investigated by characterizing the changes in morphological and EPS properties. It was found that middle polymer state aluminum (Alb) and high polymer state aluminum (Alc) performed better than monomer aluminum and oligomeric state aluminum (Ala) in reduction of specific resistance to filtration (SRF) and compressibility of wastewater sludge due to their higher charge neutralization and formed more compact flocs. Sludge was significantly acidified after addition Ala, while pH was much more stable under Alb and Alc conditioning due to their hydrolysis stability. The size of sludge flocs conditioned with Alb and Alc was small but flocs structure was denser and more compact, and floc strength is higher, while that formed from Ala is relatively large, but floc structure was loose, floc strength is relatively lower. Scanning environmental microscope analysis revealed that sludge flocs conditioned by Alb and Alc (especially PAC2.5 and Al13) exhibited obvious botryoidal structure, this is because sludge flocs formed by Alb and Alc were more compact and floc strength is high, it was easy generated plentiful tiny channels for water release. In addition, polymeric aluminum salt coagulant (Alb, Alc) had better performance in compressing extracellular polymeric substances (EPS) structure and removing sticky protein-like substances from soluble EPS fraction, contributing to improvement of sludge filtration performance. Therefore, this study provides a novel solution for improving sludge

  10. Handbook of hydrogen energy

    CERN Document Server

    Sherif, SA; Stefanakos, EK; Steinfeld, Aldo


    ""This book provides an excellent overview of the hydrogen economy and a thorough and comprehensive presentation of hydrogen production and storage methods.""-Scott E. Grasman, Rochester Institute of Technology, New York, USA

  11. Hydrogen production by Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Chaudhuri Surabhi


    Full Text Available Abstract The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical, Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source.

  12. Hydrogen transport membranes (United States)

    Mundschau, Michael V.


    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  13. Kinetics of aluminum lithium alloys (United States)

    Pletcher, Ben A.


    Aluminum lithium alloys are increasingly used in aerospace for their high strength-to-weight ratio. Additions of lithium, up to 4.2 wt% decrease the alloy density while increasing the modulus and yield strength. The metastable, second phase Al3Li or delta' is intriguing, as it remains spherical and coherent with the matrix phase, alpha, well into the overaged condition. Small interfacial strain energy allows these precipitates to remain spherical for volume fractions (VV ) of delta' less than 0.3, making this alloy system ideal for investigation of late-stage coarsening phenomena. Experimental characterization of three binary Al-Li alloys are presented as a critical test of diffusion screening theory and multi-particle diffusion simulations. Quantitative transmission electron microscopy is used to image the precipitates directly using the centered dark-field technique. Images are analyzed autonomously within a novel Matlab function that determines the center and size of each precipitate. Particle size distribution, particle growth kinetics, and maximum particle size are used to track the precipitate growth and correlate with the predictions of screening theory and multi-particle diffusion simulations. This project is the first extensive study of Al-Li alloys, in over 25 years, applying modern transmission electron microscopy and image analysis techniques. Previous studies sampled but a single alloy composition, and measured far fewer precipitates. This study investigates 3 alloys with volume fractions of the delta precipitates, VV =0.1-0.27, aged at 225C for 1 to 10 days. More than 1000 precipitates were sampled per aging time, creating more statistically significant data. Experimental results are used to test the predictions based on diffusion screening theory and multi-particle aging simulations. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check

  14. Hydrogen Technologies Safety Guide

    Energy Technology Data Exchange (ETDEWEB)

    Rivkin, C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Burgess, R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Buttner, W. [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    The purpose of this guide is to provide basic background information on hydrogen technologies. It is intended to provide project developers, code officials, and other interested parties the background information to be able to put hydrogen safety in context. For example, code officials reviewing permit applications for hydrogen projects will get an understanding of the industrial history of hydrogen, basic safety concerns, and safety requirements.

  15. Formation and properties of stabilized aluminum nanoparticles. (United States)

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


    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.

  16. Evaluation of Aluminum in Iranian Consumed Tea

    Directory of Open Access Journals (Sweden)

    Alireza Asgari


    Full Text Available Introduction: Black tea leaf is one of the most important sources of Aluminum in dietary. Therefore this research was conducted to assess the amount of Aluminum in Iranian tea infusion. Methods: To assess Aluminum in Iranian consumed tea, 27 tea samples were analyzed for Al concentration for 10 and 60 min infusion, aluminum concentration was measured with atomic absorption and the results were analyzed by SPSS.13 version. Results: The results showed that minimum and maximum concentration of Al in tea infusion for 10 min infusion was 1.59 and 18.60 mg.L-1 respectively in this regard Baroti and Bamdad tea show the highest and lowest concentration respectively in term of Al, Also Statistical analysis with pair T-test showed that infusion time doesn,t significantly effects on aluminum leaching into infusion (P>0.05. Calculation of percentage "available" Al to the human system showed that 1 L of tea can provide 17.68 % of the daily dietary intake of Al, the percentage "available" for absorption in the intestine is only 8.49 % for overall mean Al concentration. Conclusion: Therefore based on our results, tea consumption in medium values cannot cause toxic effects on human. Although it is necessary to note that tea consumption might be toxic because of effects on people with absorption or secretion problems

  17. Magnesium for Hydrogen Storage

    DEFF Research Database (Denmark)

    Vigeholm, B.; Kjøller, John; Larsen, Bent


    The reaction of hydrogen with commercially pure magnesium powder (above 99.7%) was investigated in the temperature range 250–400 °C. Hydrogen is readily sorbed above the dissociation pressure. During the initial exposure the magnesium powder sorbs hydrogen slowly below 400 °C but during the second...

  18. Biological hydrogen photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Y. [Univ. of Miami, FL (United States)


    Following are the major accomplishments of the 6th year`s study of biological hydrogen photoproduction which were supported by DOE/NREL. (1) We have been characterizing a biological hydrogen production system using synchronously growing aerobically nitrogen-fixing unicellular cyanobacterium, Synechococcus sp. Miami BG 043511. So far it was necessary to irradiate the cells to produce hydrogen. Under darkness they did not produce hydrogen. However, we found that, if the cells are incubated with oxygen, they produce hydrogen under the dark. Under 80% argon + 20% oxygen condition, the hydrogen production activity under the dark was about one third of that under the light + argon condition. (2) Also it was necessary so far to incubate the cells under argon atmosphere to produce hydrogen in this system. Argon treatment is very expensive and should be avoided in an actual hydrogen production system. We found that, if the cells are incubated at a high cell density and in a container with minimum headspace, it is not necessary to use argon for the hydrogen production. (3) Calcium ion was found to play an important role in the mechanisms of protection of nitrogenase from external oxygen. This will be a clue to understand the reason why the hydrogen production is so resistant to oxygen in this strain. (4) In this strain, sulfide can be used as electron donor for the hydrogen production. This result shows that waste water can be used for the hydrogen production system using this strain.

  19. Sensitive hydrogen leak detector (United States)

    Myneni, Ganapati Rao


    A sensitive hydrogen leak detector system using passivation of a stainless steel vacuum chamber for low hydrogen outgassing, a high compression ratio vacuum system, a getter operating at 77.5 K and a residual gas analyzer as a quantitative hydrogen sensor.

  20. The annealing behavior of hydrogen implanted into Al-Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ogura, Masahiko; Yamaji, Norisuke; Imai, Makoto; Itoh, Akio; Imanishi, Nobutsugu [Kyoto Univ. (Japan). Faculty of Engineering


    We have studied effects of not only defects but also an added elements on trap-sites of hydrogen in metals. For the purpose, we observed depth profiles and thermal behaviors of hydrogen implanted into Al-1.5at.%Si alloy samples in an implantation-temperature range of liquid nitrogen temperature (LNT) to 373K at different doses. The results were compared with those for pure aluminum samples. It was found that hydrogen is trapped as molecules in grain boundaries of Al/Si. (author)

  1. Dissolution of Globular Clusters


    Baumgardt, Holger


    Globular clusters are among the oldest objects in galaxies, and understanding the details of their formation and evolution can bring valuable insight into the early history of galaxies. This review summarises the current knowledge about the dissolution of star clusters and discusses the implications of star cluster dissolution for the evolution of the mass function of star cluster systems in galaxies.

  2. Structures of Mn clusters

    Indian Academy of Sciences (India)

    Tina M Briere; Marcel H F Sluiter; Vijay Kumar; Yoshiyuki Kawazoe


    The geometries of several Mn clusters in the size range Mn13–Mn23 are studied via the generalized gradient approximation to density functional theory. For the 13- and 19-atom clusters, the icosahedral structures are found to be most stable, while for the 15-atom cluster, the bcc structure is more favoured. The clusters show ferrimagnetic spin configurations.

  3. Hydrogen-vacancy-dislocation interactions in α-Fe (United States)

    Tehranchi, A.; Zhang, X.; Lu, G.; Curtin, W. A.


    Atomistic simulations of the interactions between dislocations, hydrogen atoms, and vacancies are studied to assess the viability of a recently proposed mechanism for the formation of nanoscale voids in Fe-based steels in the presence of hydrogen. Quantum-mechanics/molecular-mechanics method calculations confirm molecular statics simulations based on embedded atom method (EAM) potential showing that individual vacancies on the compressive side of an edge dislocation can be transported with the dislocation as it glides. Molecular dynamics simulations based on EAM potential then show, however, that vacancy clusters in the glide plane of an approaching dislocation are annihilated or reduced in size by the creation of a double-jog/climb process that is driven by the huge reduction in energy accompanying vacancy annihilation. The effectiveness of annihilation/reduction processes is not reduced by the presence of hydrogen in the vacancy clusters because typical V-H cluster binding energies are much lower than the vacancy formation energy, except at very high hydrogen content in the cluster. Analysis of a range of configurations indicates that hydrogen plays no special role in stabilizing nanovoids against jog formation processes that shrink voids. Experimental observations of nanovoids on the fracture surfaces of steels must be due to as-yet undetermined processes.

  4. Contextualizing the Cluster

    DEFF Research Database (Denmark)

    Giacomin, Valeria

    This dissertation examines the case of the palm oil cluster in Malaysia and Indonesia, today one of the largest agricultural clusters in the world. My analysis focuses on the evolution of the cluster from the 1880s to the 1970s in order to understand how it helped these two countries to integrate......-researched topic in the cluster literature – the emergence of clusters, their governance and institutional change, and competition between rival cluster locations – through the case of the Southeast Asian palm oil cluster....

  5. Hydrogen separation process (United States)

    Mundschau, Michael; Xie, Xiaobing; Evenson, IV, Carl; Grimmer, Paul; Wright, Harold


    A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than C., to a hydrogen separation membrane system comprising a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for separating a hydrogen-rich product stream from a feed stream comprising hydrogen and at least one carbon-containing gas, comprising feeding the feed stream, at an inlet pressure greater than atmospheric pressure and a temperature greater than C., to an integrated water gas shift/hydrogen separation membrane system wherein the hydrogen separation membrane system comprises a membrane that is selectively permeable to hydrogen, and producing a hydrogen-rich permeate product stream on the permeate side of the membrane and a carbon dioxide-rich product raffinate stream on the raffinate side of the membrane. A method for pretreating a membrane, comprising: heating the membrane to a desired operating temperature and desired feed pressure in a flow of inert gas for a sufficient time to cause the membrane to mechanically deform; decreasing the feed pressure to approximately ambient pressure; and optionally, flowing an oxidizing agent across the membrane before, during, or after deformation of the membrane. A method of supporting a hydrogen separation membrane system comprising selecting a hydrogen separation membrane system comprising one or more catalyst outer layers deposited on a hydrogen transport membrane layer and sealing the hydrogen separation membrane system to a porous support.

  6. An investigation on the compressibility of aluminum/nano-alumina composite powder prepared by blending and mechanical milling

    Energy Technology Data Exchange (ETDEWEB)

    Razavi Hesabi, Z. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran 14588 (Iran, Islamic Republic of); Hafizpour, H.R. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran 14588 (Iran, Islamic Republic of); Simchi, A. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran 14588 (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran 14588 (Iran, Islamic Republic of)], E-mail:


    The densification response of aluminum powder reinforced with 5 vol.% nanometric alumina particles (35 nm) during uniaxial compaction in a rigid die was studied. The composite powder was prepared by blending and mechanical milling procedures. To determine the effect of the reinforcement nanoparticles on the compressibility of aluminum powder, monolithic Al powder, i.e. without the addition of alumina, was also examined. It was shown that at the early stage of compaction when the rearrangement of particles is the dominant mechanism of the densification, disintegration of the nanoparticle clusters and agglomerates under the applied load contributes in the densification of the composite powder prepared by blending method. As the compaction pressure increases, however, the load partitioning effect of the nanoparticles decreases the densification rate of the powder mixture, resulting in a lower density compared to the monolithic aluminum. It was also shown that mechanical milling significantly impacts the compressibility of the unreinforced and reinforced aluminum powders. Morphological changes of the particles upon milling increase the contribution of particle rearrangement in densification whilst the plastic deformation mechanism is significantly retarded due to the work-hardening effect of the milling process. Meanwhile, the distribution of alumina nanoparticles is improved by mechanical milling, which in fact, affects the compressibility of the composite powder. This paper addresses the effect of mechanical milling and reinforcement nanoparticles on the compressibility of aluminum powder.

  7. Clustering in analytical chemistry. (United States)

    Drab, Klaudia; Daszykowski, Michal


    Data clustering plays an important role in the exploratory analysis of analytical data, and the use of clustering methods has been acknowledged in different fields of science. In this paper, principles of data clustering are presented with a direct focus on clustering of analytical data. The role of the clustering process in the analytical workflow is underlined, and its potential impact on the analytical workflow is emphasized.

  8. Scattering influences in quantitative fission neutron radiography for the in situ analysis of hydrogen distribution in metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Börries, S., E-mail: [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany); Metz, O.; Pranzas, P.K. [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany); Bücherl, T. [ZTWB Radiochemie München (RCM), Technische Universität München (TUM), Walther-Meissner-Str. 3, D-85748 Garching (Germany); Söllradl, S. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII), Technische Universität München (TUM), Lichtenbergstr. 1, D-85748 Garching (Germany); Dornheim, M.; Klassen, T.; Schreyer, A. [Helmholtz-Zentrum Geesthacht, Centre for Materials and Coastal Research, Max-Planck-Strasse 1, D-21502 Geesthacht (Germany)


    In situ neutron radiography allows for the time-resolved study of hydrogen distribution in metal hydrides. However, for a precise quantitative investigation of a time-dependent hydrogen content within a host material, an exact knowledge of the corresponding attenuation coefficient is necessary. Additionally, the effect of scattering has to be considered as it is known to violate Beer's law, which is used to determine the amount of hydrogen from a measured intensity distribution. Within this study, we used a metal hydride inside two different hydrogen storage tanks as host systems, consisting of steel and aluminum. The neutron beam attenuation by hydrogen was investigated in these two different setups during the hydrogen absorption process. A linear correlation to the amount of absorbed hydrogen was found, allowing for a readily quantitative investigation. Further, an analysis of scattering contributions on the measured intensity distributions was performed and is described in detail.


    Energy Technology Data Exchange (ETDEWEB)

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


    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

  10. Aluminum phosphate ceramics for waste storage (United States)

    Wagh, Arun; Maloney, Martin D


    The present disclosure describes solid waste forms and methods of processing waste. In one particular implementation, the invention provides a method of processing waste that may be particularly suitable for processing hazardous waste. In this method, a waste component is combined with an aluminum oxide and an acidic phosphate component in a slurry. A molar ratio of aluminum to phosphorus in the slurry is greater than one. Water in the slurry may be evaporated while mixing the slurry at a temperature of about C. The mixed slurry may be allowed to cure into a solid waste form. This solid waste form includes an anhydrous aluminum phosphate with at least a residual portion of the waste component bound therein.

  11. NASA-427: A New Aluminum Alloy (United States)

    Nabors, Sammy A.


    NASA's Marshall Space Flight Center researchers have developed a new, stronger aluminum alloy, ideal for cast aluminum products that have powder or paint-baked thermal coatings. With advanced mechanical properties, the NASA-427 alloy shows greater tensile strength and increased ductility, providing substantial improvement in impact toughness. In addition, this alloy improves the thermal coating process by decreasing the time required for heat treatment. With improvements in both strength and processing time, use of the alloy provides reduced materials and production costs, lower product weight, and better product performance. The superior properties of NASA-427 can benefit many industries, including automotive, where it is particularly well-suited for use in aluminum wheels.

  12. Dynamic recrystallization behavior of commercial pure aluminum

    Institute of Scientific and Technical Information of China (English)

    LI Hui-zhong; ZHANG Xin-ming; CHEN Ming-an; LIU Zi-juan


    The flow stress feature and microstructure evolvement of a commercial pure aluminum were investigated by compression on Gleeble-1500 dynamic materials test machine. Optical microscopy (OM) and transmission electron microscopy (TEM) were applied to analyze the deformation microstructure of the commercial pure aluminum.The results show that the flow stress tends to be constant after a peak value and the dynamic recovery occurs when the deformation temperatures is 220 ℃ with the strain rate of 0.01 s-1; while the dynamic recrystallization occurs when the deformation temperature is higher than 380 ℃, and the flow stress exhibits a single peak at 460 ℃ with different strain rates from 0.001 s-1 to 1 s-1, and continuous dynamic recrystallization and geometric dynamic recrystallization occur during the hot compression of the commercial pure aluminum.

  13. Lithium-aluminum-magnesium electrode composition (United States)

    Melendres, Carlos A.; Siegel, Stanley


    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  14. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum. (United States)

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan


    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

  15. The Effect of Anodic Oxide Films on the Nickel-Aluminum Reaction in Aluminum Braze Sheet (United States)

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


    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.

  16. Reducing aluminum dust explosion hazards: case study of dust inerting in an aluminum buffing operation. (United States)

    Myers, Timothy J


    Metal powders or dusts can represent significant dust explosion hazards in industry, due to their relatively low ignition energy and high explosivity. The hazard is well known in industries that produce or use aluminum powders, but is sometimes not recognized by facilities that produce aluminum dust as a byproduct of bulk aluminum processing. As demonstrated by the 2003 dust explosion at aluminum wheel manufacturer Hayes Lemmerz, facilities that process bulk metals are at risk due to dust generated during machining and finishing operations [U.S. Chemical Safety and Hazard Investigation Board, Investigation Report, Aluminum Dust Explosion Hayes Lemmerz International, Inc., Huntington, Indiana, Report No. 2004-01-I-IN, September 2005]. Previous studies have shown that aluminum dust explosions are more difficult to suppress with flame retardants or inerting agents than dust explosions fueled by other materials such as coal [A.G. Dastidar, P.R. Amyotte, J. Going, K. Chatrathi, Flammability limits of dust-minimum inerting concentrations, Proc. Saf. Progr., 18-1 (1999) 56-63]. In this paper, an inerting method is discussed to reduce the dust explosion hazard of residue created in an aluminum buffing operation as the residue is generated. This technique reduces the dust explosion hazard throughout the buffing process and within the dust collector systems making the process inherently safer. Dust explosion testing results are presented for process dusts produced during trials with varying amounts of flame retardant additives.

  17. Materials for hydrogen storage

    Directory of Open Access Journals (Sweden)

    Andreas Züttel


    The goal is to pack hydrogen as close as possible, i.e. to reach the highest volumetric density by using as little additional material as possible. Hydrogen storage implies the reduction of an enormous volume of hydrogen gas. At ambient temperature and atmospheric pressure, 1 kg of the gas has a volume of 11 m3. To increase hydrogen density, work must either be applied to compress the gas, the temperature decreased below the critical temperature, or the repulsion reduced by the interaction of hydrogen with another material.

  18. Modification of Metal Complex on the Stereoselective Hydrogenation of 2,3-Butanedione

    Institute of Scientific and Technical Information of China (English)


    The modification of some metal complexes on Pt/Al2O3 clusters leads to remarkable increases in both the activity and the selectivity for meso-2,3-butanediol in the stereoselective hydrogenation of 2,3-butanedione.

  19. Interaction of catechins with aluminum in vitro

    Institute of Scientific and Technical Information of China (English)

    唐德松; 沈生荣; 陈勋; 张玉艳; 许重阳


    Tea is one of the most popular beverages, consumed by over two thirds of the world's population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum's known adverse effect on human health. Investigation of the interactions of catechins with A13+ showed that during the interaction of catechins with A13+, the UV-vis spectrum of catechins was changed. Absorption of EGCG at 274 nm decreased and increased at 322 nm; EC and C's at 278 nm changed little. The ratio of A13+ to EGCG was 1:1 in pH 5.0 buffer solution; in pH 6.2 buffer solution, the ratio in the A1-EGCG complex was 1:1. Interestingly, while the ratio reached to over 2, after the complex of A1-EGCG started polymerization, the ratio in the polymer was 2:1. In pH 6.2 buffer solution, the complex behavior of C with A13+ was the same as that of EGCG, with a little difference for EC. When the ratio of A13+ to EC was1. It was found that the ratio of A13+ to EC in the polymer was 1:1. Polymerization of A1-catechin complexes might reduce aluminum absorption in the intestine. Kow value was also employed to study the properties of aluminum species in tea infusion (at gastric and intestine pH condition) and the effect of catechins and tea polyphenols on Kow in buffer solution. Results showed that Kow value rose much higher at the intestine pH than at the gastric pH. Tea polyphenols and catechins could greatly reduce aluminum Kow value in acetic buffer,indicating that these compounds may reduce aluminum absorption during tea intake.

  20. Interaction of catechins with aluminum in vitro

    Institute of Scientific and Technical Information of China (English)

    唐德松; 沈生荣; 陈勋; 张玉艳; 许重阳


    Tea is one of the most popular beverages, consumed by over two thirds of the world's population; but the aluminum accumulation property of tea plant is becoming the focus of many researches because of aluminum's known adverse effect on human health. Investigation of the interactions of catechins with Al3+ showed that during the interaction of catechins with Al3+, the UV-vis spectrum of catechins was changed. Absorption of EGCG at 274 nm decreased and increased at 322 nm; EC and C's at 278 nm changed little. The ratio of Al3+ to EGCG was 1:1 in pH 5.0 buffer solution; in pH 6.2 buffer solution, the ratio in the Al-EGCG complex was 1:1. Interestingly, while the ratio reached to over 2, after the complex of Al-EGCG started polymerization, the ratio in the polymer was 2:1. In pH 6.2 buffer solution, the complex behavior of C with Al3+ was the same as that of EGCG, with a little difference for EC. When the ratio of Al3+ to EC was 1. It was found that the ratio of Al3+ to EC in the polymer was 1:1. Polymerization of Al-catechin complexes might reduce aluminum absorption in the intestine. Kow value was also employed to study the properties of aluminum species in tea infusion (at gastric and intestine pH condition) and the effect of catechins and tea polyphenols on Kow in buffer solution. Results showed that Kow value rose much higher at the intestine pH than at the gastric pH. Tea polyphenols and catechins could greatly reduce aluminum Kow value in acetic buffer, indicating that these compounds may reduce aluminum absorption during tea intake.

  1. Hydrogen energy assessment

    Energy Technology Data Exchange (ETDEWEB)

    Salzano, F J; Braun, C [eds.


    The purpose of this assessment is to define the near term and long term prospects for the use of hydrogen as an energy delivery medium. Possible applications of hydrogen are defined along with the associated technologies required for implementation. A major focus in the near term is on industrial uses of hydrogen for special applications. The major source of hydrogen in the near term is expected to be from coal, with hydrogen from electric sources supplying a smaller fraction. A number of potential applications for hydrogen in the long term are identified and the level of demand estimated. The results of a cost benefit study for R and D work on coal gasification to hydrogen and electrolytic production of hydrogen are presented in order to aid in defining approximate levels of R and D funding. A considerable amount of data is presented on the cost of producing hydrogen from various energy resources. A key conclusion of the study is that in time hydrogen is likely to play a role in the energy system; however, hydrogen is not yet competitive for most applications when compared to the cost of energy from petroleum and natural gas.

  2. Effect of Electrolyte on the Dissolution of Aluminum from Acid Sois and the Distribution of Aluminum Forms in Soil Solution

    Institute of Scientific and Technical Information of China (English)



    KCl,CaCl2,NH4Cl,NaCl,K2SO4 and KF solutions were used for studying the effects of cations and anions on the dissolution of aluminum and the distribution of aluminum forms respectively.Power of exchanging and releasing aluminum of four kinds of cations was in the decreasing order Ca2+>K+>NH4+>Na+,The dissolution of aluminum increased with the cation concentration.The adsorption affinity of various soils fro aluminum was different.The aluminum in the soil with a stronger adsorption affinity was diffcult to be exchanged and released by cations.The Al-F complexes were main species of inorganic aluminum at a low concentration of cations,while Al3+ became major species of inorganic aluminum at a hiht concentration of cations .The results on the effct of anions indicated that the concentrations of total aluminum,three kinds of inorganc aluminum(Al3+,Al-F and Al-OH complexes) and organic aluminum complexes(Al-OM) when SO42- was added into soil suspension were lower than those when Cl- was added.The dissolution of aluminum from soils and the distribution of aluminum forms in solution were affected by the adsorption of F- on the soil.For soils with strong affinity for F-,the concentrations of the three inorganic aluminum species in soil solution after addition of F- were lower than those after addition of Cl-;but for soils with weak affinity for F-,the concentrations of Al3+ and Al-OM were lower and the concentrations of Al-F complexes and total inorganic aluminum after addition of F- were higher than those after addition of Cl- .The increase of F- concentration in soil solution accelerated the dissolution of aluminum from soils.

  3. Composite purification technology and mechanism of recycled aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    房文斌; 耿耀宏; 安阁英; 叶荣茂


    Iron-rich inclusions in aluminum alloys can be effectively removed by composite purification of sedimentation and filtration technology.The results show that the purposed method has no negative effects on aluminum alloys and obviously improve their mechanical properties.

  4. Understanding Aspects of Aluminum Exposure in Alzheimer's Disease Development. (United States)

    Kandimalla, Ramesh; Vallamkondu, Jayalakshmi; Corgiat, Edwin B; Gill, Kiran Dip


    Aluminum is a ubiquitously abundant nonessential element. Aluminum has been associated with neurodegenerative diseases such as Alzheimer's disease (AD), amyotrophic lateral sclerosis, and dialysis encephalopathy. Many continue to regard aluminum as controversial although increasing evidence supports the implications of aluminum in the pathogenesis of AD. Aluminum causes the accumulation of tau protein and Aβ protein in the brain of experimental animals. Aluminum induces neuronal apoptosis in vivo and in vitro, either by endoplasmic stress from the unfolded protein response, by mitochondrial dysfunction, or a combination of them. Some, people who are exposed chronically to aluminum, either from through water and/or food, have not shown any AD pathology, apparently because their gastrointestinal barrier is more effective. This article is written keeping in mind mechanisms of action of aluminum neurotoxicity with respect to AD.

  5. [Aluminum induces chromosome aberrations in wheat root meristem cells]. (United States)

    Bulanova, N V; Synzynys, B I; Koz'min, G V


    The yield and pattern of chromosome structure aberrations in wheat seedlings treated with aluminum nitrate and aluminum sulfate at various concentrations have been determined by the anaphase method. Aluminum has a genotoxic effect causing genome, chromatid, and chromosome aberrations in apical root meristem cells. The relationship between the total yield of structural mutations and the aluminum concentration follows a bell-shaped curve. The mutagenic activity of aluminum nitrate peaks at 10(-3) mg/ml, which is twice as high as the permissible concentration limit (PCL) of aluminum in potable water. The maximum of the mutagenic activity of aluminum sulfate is observed at 5 x 10(-4) mg/ml, i.e., one PCL. Tap water boiled for 2 h in an aluminum vessel has virtually no genotoxic effect on wheat cells.

  6. Method of winning aluminum metal from aluminous ore (United States)

    Loutfy, Raouf O.; Keller, Rudolf; Yao, Neng-Ping


    Aluminous ore such as bauxite containing alumina is blended with coke or other suitable form of carbon and reacted with sulfur gas at an elevated temperature. For handling, the ore and coke can be extruded into conveniently sized pellets. The reaction with sulfur gas produces molten aluminum sulfide which is separated from residual solid reactants and impurities. The aluminum sulfide is further increased in temperature to cause its decomposition or sublimation, yielding aluminum subsulfide liquid (AlS) and sulfur gas that is recycled. The aluminum monosulfide is then cooled to below its disproportionation temperature to again form molten aluminum sulfide and aluminum metal. A liquid-liquid or liquid-solid separation, depending on the separation temperature, provides product aluminum and aluminum sulfide for recycle to the disproportionation step.

  7. Anodization process produces opaque, reflective coatings on aluminum (United States)


    Opaque, reflective coatings are produced on aluminum articles by an anodizing process wherein the anodizing bath contains an aqueous dispersion of finely divided insoluble inorganic compounds. These particles appear as uniformly distributed occlusions in the anodic deposit on the aluminum.

  8. Low Mass, Aluminum NOFBX Combustion Chamber Development Project (United States)

    National Aeronautics and Space Administration — Our team proposes to define a diffusion bonding process for aluminum as an enabling step to ultimately develop an innovative, lightweight, long life, aluminum...

  9. Refined Aluminum Industry Suffers From Deficit and Western Investment Accelerates

    Institute of Scientific and Technical Information of China (English)


    <正>Under the backdrop of loss of the entire refined aluminum industry,the investment in electrolytic aluminum accelerates.The reporter learnt from a recent survey that,many companies including Shandong Xinfa Group,East Hope

  10. Photobiological hydrogen production. (United States)

    Asada, Y; Miyake, J


    The principles and recent progress in the research and development of photobiological hydrogen production are reviewed. Cyanobacteria produce hydrogen gas using nitrogenase and/or hydrogenase. Hydrogen production mediated by native hydrogenases in cyanobacteria occurs under in the dark under anaerobic conditions by degradation of intracellular glycogen. In vitro and in vivo coupling of the cyanobacterial photosynthetic system with a clostridial hydrogenase via cyanobacterial ferredoxin was demonstrated in the presence of light. Genetic transformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum was successful; the active enzyme was expressed in PCC7942. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Coculture of Rhodobacter and Clostriudium was applied for hydrogen production from glucose. A mutant strain of Rhodobacter sphaeroides RV whose light-harvesting proteins were altered was obtained by UV irradiation. Hydrogen productivity by the mutant was improved when irradiated with monochromatic light of some wavelengths. The development of photobioreactors for hydrogen production is also reviewed.

  11. Hydrogen energy for beginners

    CERN Document Server


    This book highlights the outstanding role of hydrogen in energy processes, where it is the most functional element due to its unique peculiarities that are highlighted and emphasized in the book. The first half of the book covers the great natural hydrogen processes in biology, chemistry, and physics, showing that hydrogen is a trend that can unite all natural sciences. The second half of the book is devoted to the technological hydrogen processes that are under research and development with the aim to create the infrastructure for hydrogen energetics. The book describes the main features of hydrogen that make it inalienable player in processes such as fusion, photosynthesis, and metabolism. It also covers the methods of hydrogen production and storage, highlighting at the same time the exclusive importance of nanotechnologies in those processes.

  12. Iron and aluminum in Alzheimer's disease. (United States)

    Di Lorenzo, Francesco; Di Lorenzo, Berardino


    In this case presentation, a woman with high serum levels of aluminum was treated with chelation therapy with deferoxamine and ascorbic acid. This patient was initially bedridden and the clinical situation was complicated by epileptic seizures. After the chelation therapy, the clinical condition was ameliorated and the therapy continued without the correlation to aluminum serum levels. The role of metals in neurodegenerative disorders and the correlation between iron metabolism and amyloid beta peptide are described. This case suggests chelation therapy could represent a promising therapeutic option for this dramatic disease.

  13. Sound absorption property of openpore aluminum foams

    Directory of Open Access Journals (Sweden)

    WANG Fang


    Full Text Available This paper presents a study on sound absorption property of aluminum foam by evaluating its sound absorption coefficients using standing wave tube method. Experimental results showed that the average values of sound absorption coefficients (over the test frequency range are all above 0.4, which indicate very good sound absorption property of the aluminum foams. The sound absorption coefficient is affected by frequency and pore structure, and reaches its maximum value at around 1 000 Hz. With the increase of porosity and decrease of cell diameter, the sound absorption coefficient values increase.

  14. Aluminum plasmonic metamaterials for structural color printing. (United States)

    Cheng, Fei; Gao, Jie; Stan, Liliana; Rosenmann, Daniel; Czaplewski, David; Yang, Xiaodong


    We report a structural color printing platform based on aluminum plasmonic metamaterials supporting near perfect light absorption and narrow-band spectral response tunable across the visible spectrum to realize high-resolution, angle-insensitive color printing with high color purity and saturation. Additionally, the fabricated metamaterials can be protected by a transparent polymer thin layer for ambient use with further improved color performance. The demonstrated structural color printing with aluminum plasmonic metamaterials offers great potential for relevant applications such as security marking and information storage.

  15. Development of deep drawn aluminum piston tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.C.; Bronder, R.L.; Kilgard, L.W.; Evans, M.C.; Ormsby, A.E.; Spears, H.R.; Wilson, J.D.


    An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.

  16. 2008 Molecular and Ionic Clusters - September 7-12, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Jeremy M. Hutson


    The Gordon Research Conference on Molecular and Ionic Clusters was held at Centre Paul Langevin, Aussois, France, September 7-12, 2008. The Conference was well-attended with 129 participants (attendees list attached). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. The conference covered the spectroscopy, dynamics, and reactivity of a wide range of cluster types and sizes, including helium nanodroplets, metal clusters, ionic clusters, hydrogen-bonded networks, and clusters involving biological molecules. Special sessions on cold-molecule collisions and aerosols are also planned. Both experimental and theoretical aspects of cluster science will be well-represented at the conference.

  17. Modern trends and challenges of development of global aluminum industry

    Directory of Open Access Journals (Sweden)

    M. N. Dudin


    Full Text Available This article overviews complex study into modern trends and challenges of development of global aluminum industry. Dynamics, structure, and segmentation of global aluminum market are discussed in terms of systematic analysis. On this basis strategic map of the industry has been plotted and five forces of competition on global aluminum market have been determined which will influence directly on functioning and development of aluminum producing companies.

  18. Sunshine Group Builds High-End Aluminum Product Industrial Base

    Institute of Scientific and Technical Information of China (English)


    In order to propel development of the aluminum industry to move toward featured,specialized,and ecological directions,Sunlight Sanyuan Aluminum Company plans to expropriate 300 mu of land in Hanjiang District of Putian City,Fujian province,where it plans to construct high-end aluminum product industrial park,introduce the world’s most advanced fully automatic production equipment and technologies for aluminum profile and

  19. Modeling the reaction kinetics of a hydrogen generator onboard a fuel cell -- Electric hybrid motorcycle (United States)

    Ganesh, Karthik

    Owing to the perceived decline of the fossil fuel reserves in the world and environmental issues like pollution, conventional fuels may be replaced by cleaner alternative fuels. The potential of hydrogen as a fuel in vehicular applications is being explored. Hydrogen as an energy carrier potentially finds applications in internal combustion engines and fuel cells because it is considered a clean fuel and has high specific energy. However, at 6 to 8 per kilogram, not only is hydrogen produced from conventional methods like steam reforming expensive, but also there are storage and handling issues, safety concerns and lack of hydrogen refilling stations across the country. The purpose of this research is to suggest a cheap and viable system that generates hydrogen on demand through a chemical reaction between an aluminum-water slurry and an aqueous sodium hydroxide solution to power a 2 kW fuel cell on a fuel cell hybrid motorcycle. This reaction is essentially an aluminum-water reaction where sodium hydroxide acts as a reaction promoter or catalyst. The Horizon 2000 fuel cell used for this purpose has a maximum hydrogen intake rate of 28 lpm. The study focuses on studying the exothermic reaction between the reactants and proposes a rate law that best describes the rate of generation of hydrogen in connection to the surface area of aluminum available for the certain reaction and the concentration of the sodium hydroxide solution. Further, the proposed rate law is used in the simulation model of the chemical reactor onboard the hybrid motorcycle to determine the hydrogen flow rate to the fuel cell with time. Based on the simulated rate of production of hydrogen from the chemical system, its feasibility of use on different drive cycles is analyzed. The rate of production of hydrogen with a higher concentration of sodium hydroxide and smaller aluminum powder size was found to enable the installation of the chemical reactor on urban cycles with frequent stops and starts

  20. Hydrogen Fuel Cells and Storage Technology: Fundamental Research for Optimization of Hydrogen Storage and Utilization

    Energy Technology Data Exchange (ETDEWEB)

    Perret, Bob; Heske, Clemens; Nadavalath, Balakrishnan; Cornelius, Andrew; Hatchett, David; Bae, Chusung; Pang, Tao; Kim, Eunja; Hemmers, Oliver


    Design and development of improved low-cost hydrogen fuel cell catalytic materials and high-capacity hydrogenn storage media are paramount to enabling the hydrogen economy. Presently, effective and durable catalysts are mostly precious metals in pure or alloyed form and their high cost inhibits fuel cell applications. Similarly, materials that meet on-board hydrogen storage targets within total mass and volumetric constraints are yet to be found. Both hydrogen storage performance and cost-effective fuel cell designs are intimately linked to the electronic structure, morphology and cost of the chosen materials. The FCAST Project combined theoretical and experimental studies of electronic structure, chemical bonding, and hydrogen adsorption/desorption characteristics of a number of different nanomaterials and metal clusters to develop better fundamental understanding of hydrogen storage in solid state matrices. Additional experimental studies quantified the hydrogen storage properties of synthesized polyaniline(PANI)/Pd composites. Such conducting polymers are especially interesting because of their high intrinsic electron density and the ability to dope the materials with protons, anions, and metal species. Earlier work produced contradictory results: one study reported 7% to 8% hydrogen uptake while a second study reported zero hydrogen uptake. Cost and durability of fuel cell systems are crucial factors in their affordability. Limits on operating temperature, loss of catalytic reactivity and degradation of proton exchange membranes are factors that affect system durability and contribute to operational costs. More cost effective fuel cell components were sought through studies of the physical and chemical nature of catalyst performance, characterization of oxidation and reduction processes on system surfaces. Additional development effort resulted in a new hydrocarbon-based high-performance sulfonated proton exchange membrane (PEM) that can be manufactured at low

  1. Shanxi Zhaofeng Aluminum Industry is Planning Oversea Listing

    Institute of Scientific and Technical Information of China (English)


    <正>Shanxi Yangquan Coal Industry(Group)Co., Ltd.intends to promote its subsidiary company Shanxi Zhaofeng Aluminum Metallurgy Co Ltd (hereinafter referred to as Zhaofeng Aluminum Metallurgy)to seek oversea listing.If its effort succeeds,Zhaofeng Aluminum Metallurgy will become the third public listed company under Yangquan Group.

  2. 21 CFR 582.1781 - Sodium aluminum phosphate. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium aluminum phosphate. 582.1781 Section 582.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Additives § 582.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions...

  3. 21 CFR 182.1781 - Sodium aluminum phosphate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium aluminum phosphate. 182.1781 Section 182.1781 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate....

  4. [Science and Technology and Recycling: Instructional Materials on Aluminum. (United States)

    Aluminum Association, New York, NY.

    Educational materials on the manufacture and use of aluminum are assembled in this multi-media unit for use by junior high and secondary school students. Student booklets and brochures include: "The Story of Aluminum,""Uses of Aluminum,""Independent Study Guide for School Research Projects,""Questions and Answers About Litter, Solid Waste, and…

  5. 2009 China’s Aluminum Fabrication Industrial Development Report

    Institute of Scientific and Technical Information of China (English)


    <正>1 Overview of Aluminum Fabrication Industry Despite the impact of 2008’s financial crisis on China’s aluminum fabrication industry, China’s output of aluminum products remained the world’s largest in 2009, against overall steady

  6. New Tax Rebate Policy Favorable to Aluminum Processing Industry

    Institute of Scientific and Technical Information of China (English)


    <正>China has made the decision to increase export tax rebate rate for part of the non-ferrous products from April 1, 2009, among which the export tax rebate for aluminum alloy hollow profiles and other aluminum alloy profiles goes up to 13%. The new policy is a piece of good news for aluminum processing

  7. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide. (United States)


    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining...

  8. Shanxi Will Build Aluminum Deep Processing Industrial Park

    Institute of Scientific and Technical Information of China (English)


    As a province with high coal output,Shanx boasts rich electrolytic aluminum resources.On January 7,the reporter learned from the Provincial Commission of Economy and Information Technology that in order to continually expand the size of aluminum industry,extend aluminum industrial chain,so

  9. Status Quo of China’s Aluminum Sheet & Strip Industry

    Institute of Scientific and Technical Information of China (English)


    <正>Aluminum sheet & strip products are one of the major product varieties in the aluminum processing industry, they also provide indis-pensable basic materials for the development of national economy. In recent years, driven by rapid economic growth, China’s investment in aluminum sheet & strip industry continued to

  10. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian


    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  11. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian


    Hydrogen is an environmentally attractive transportation fuel that has the potential to displace fossil fuels. The Freedom CAR and Freedom FUEL initiatives emphasize the importance of hydrogen as a future transportation fuel. Presently, Las Vegas has one hydrogen fueling station powered by natural gas. However, the use of traditional sources of energy to produce hydrogen does not maximize the benefit. The hydrogen fueling station developed under this grant used electrolysis units and solar energy to produce hydrogen fuel. Water and electricity are furnished to the unit and the output is hydrogen and oxygen. Three vehicles were converted to utilize the hydrogen produced at the station. The vehicles were all equipped with different types of technologies. The vehicles were used in the day-to-day operation of the Las Vegas Valley Water District and monitoring was performed on efficiency, reliability and maintenance requirements. The research and demonstration utilized for the reconfiguration of these vehicles could lead to new technologies in vehicle development that could make hydrogen-fueled vehicles more cost effective, economical, efficient and more widely used. In order to advance the development of a hydrogen future in Southern Nevada, project partners recognized a need to bring various entities involved in hydrogen development and deployment together as a means of sharing knowledge and eliminating duplication of efforts. A road-mapping session was held in Las Vegas in June 2006. The Nevada State Energy Office, representatives from DOE, DOE contractors and LANL, NETL, NREL were present. Leadership from the National hydrogen Association Board of Directors also attended. As a result of this session, a roadmap for hydrogen development was created. This roadmap has the ability to become a tool for use by other road-mapping efforts in the hydrogen community. It could also become a standard template for other states or even countries to approach planning for a hydrogen

  12. Hydrogen energy systems studies

    Energy Technology Data Exchange (ETDEWEB)

    Ogden, J.M.; Steinbugler, M.; Kreutz, T. [Princeton Univ., NJ (United States). Center for Energy and Environmental Studies


    In this progress report (covering the period May 1997--May 1998), the authors summarize results from ongoing technical and economic assessments of hydrogen energy systems. Generally, the goal of their research is to illuminate possible pathways leading from present hydrogen markets and technologies toward wide scale use of hydrogen as an energy carrier, highlighting important technologies for RD and D. Over the past year they worked on three projects. From May 1997--November 1997, the authors completed an assessment of hydrogen as a fuel for fuel cell vehicles, as compared to methanol and gasoline. Two other studies were begun in November 1997 and are scheduled for completion in September 1998. The authors are carrying out an assessment of potential supplies and demands for hydrogen energy in the New York City/New Jersey area. The goal of this study is to provide useful data and suggest possible implementation strategies for the New York City/ New Jersey area, as the Hydrogen Program plans demonstrations of hydrogen vehicles and refueling infrastructure. The authors are assessing the implications of CO{sub 2} sequestration for hydrogen energy systems. The goals of this work are (a) to understand the implications of CO{sub 2} sequestration for hydrogen energy system design; (b) to understand the conditions under which CO{sub 2} sequestration might become economically viable; and (c) to understand design issues for future low-CO{sub 2} emitting hydrogen energy systems based on fossil fuels.

  13. What Makes Clusters Decline?

    DEFF Research Database (Denmark)

    Østergaard, Christian Richter; Park, Eun Kyung


    Most studies on regional clusters focus on identifying factors and processes that make clusters grow. However, sometimes technologies and market conditions suddenly shift, and clusters decline. This paper analyses the process of decline of the wireless communication cluster in Denmark....... The longitudinal study on the high-tech cluster reveals that technological lock-in and exit of key firms have contributed to decline. Entrepreneurship has a positive effect on the cluster’s adaptive capabilities, while multinational companies have contradicting effects by bringing in new resources to the cluster...

  14. Loften Aluminum Aluminum Foil Output to Reach 120,000 Tons in 2012

    Institute of Scientific and Technical Information of China (English)


    <正>Loften Aluminum Co., Ltd. was founded in 2000 Boxing County, Shandong Province. On 31 March 2010, Loften became an A-share listed company, creating favorable conditions for raising funds to expand its operations.

  15. Insights on Clusters Formation Mechanism by Time of Flight Mass Spectrometry. 2. The Case of Acetone-Water Clusters (United States)

    Apicella, B.; Li, X.; Passaro, M.; Russo, C.


    This paper is the second of a series dealing with clusters formation mechanism. In part 1, water clusters with the addition of an electrophilic molecule such as ethanol were studied by Time Of Flight Mass Spectrometry (TOFMS). Mass distributions of molecular clusters of ethanol, water and ethanol-water mixed clusters, were obtained by means of two different ionization methods: Electron Ionization (EI) and picosecond laser Photo-Ionization (PI) at a wavelength of 355 nm. In part 2, the same experimental approach was employed to obtain mass spectra of clusters generated by acetone-water binary mixtures with a different composition. Strong dependence of the mass spectra of clusters with EI and PI on the acetone-water mixing ratio was observed. It was shown that the spectral pattern changes gradually and water-rich cluster signals become fainter while acetone-rich cluster signals become more intensive with increasing acetone concentrations from 0.3% to 40%. Owing to the hydrogen bond acceptor character of acetone, its self-association is discouraged with respect to ethanol. The autocorrelation function (AF) was used to analyze the variation of the water clusters composition with the increase of the acetone concentration in terms of fundamental periodicities. However, although acetone and ethanol present a very different hydrogen-bonding ability, similarly to ethanol-water system, in acetone-water system the formation of water-rich clusters and subsequent metastable fragmentation are the dominant process that determine the clusters distribution, irrespective of the ionization process, while the ionization process significantly affects the acetone-rich clusters distribution.

  16. Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie L.; Vesborg, Peter Christian Kjærgaard


    -abundant alternatives are needed for large-scale use. We show that bioinspired molecular clusters based on molybdenum and sulphur evolve hydrogen at rates comparable to that of platinum. The incomplete cubane-like clusters (Mo3S 4) efficiently catalyse the evolution of hydrogen when coupled to a p-type Si semiconductor......The production of fuels from sunlight represents one of the main challenges in the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and although platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution, earth...... that harvests red photons in the solar spectrum. The current densities at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10% (ref. 16). The experimental observations are supported by density functional theory...

  17. Influence of M-B (M = Fe, Co, Ni) on aluminum-water reaction (United States)

    Meng, H. X.; Wang, N.; Dong, Y. M.; Jia, Z. L.; Gao, L. J.; Chai, Y. J.


    In this work, the aluminum-water reaction induced by Fe-B, Co-B and Ni-B particles was studied. The catalysts were mixtures of the metal boride and metallic particles. The chainlike Fe-B catalyst forms a network structure under the influence of an external magnetic field and has a large specific surface area. Aggregated particles of Co-B and Ni-B catalyst have small specific surface area. Catalytic activity in the initial corrosion of aluminum increases with increasing Fe-B content because of the large specific surface area and the formation of a micro galvanic cell. However, the amount of hydrogen generated slowly decreases with increasing amount of Co-B and Ni-B. The activity of Fe-B, Co-B and Ni-B in the initial Al/H2O reaction decreases in the order Fe-B > Ni-B > Co-B. The calculated apparent activation energies in the presence of Fe-B, Co-B and Ni catalysts are 38.2, 39 and 29.6 kJ mol-1, respectively. Aluminum is rapidly and completely corroded in a weakly alkaline solution (pH < 10) after consecutive additions of Al batches because of high concentrations of OH- in the local domain and an increase in the amount of Al(OH)3 precipitate.

  18. Molecular Contamination on Anodized Aluminum Components of the Genesis Science Canister (United States)

    Burnett, D. S.; McNamara, K. M.; Jurewicz, A.; Woolum, D.


    Inspection of the interior of the Genesis science canister after recovery in Utah, and subsequently at JSC, revealed a darkening on the aluminum canister shield and other canister components. There has been no such observation of film contamination on the collector surfaces, and preliminary spectroscopic ellipsometry measurements support the theory that the films observed on the anodized aluminum components do not appear on the collectors to any significant extent. The Genesis Science Team has made an effort to characterize the thickness and composition of the brown stain and to determine if it is associated with molecular outgassing.Detailed examination of the surfaces within the Genesis science canister reveals that the brown contamination is observed to varying degrees, but only on surfaces exposed in space to the Sun and solar wind hydrogen. In addition, the materials affected are primarily composed of anodized aluminum. A sharp line separating the sun and shaded portion of the thermal closeout panel is shown. This piece was removed from a location near the gold foil collector within the canister. Future plans include a reassembly of the canister components to look for large-scale patterns of contamination within the canister to aid in revealing the root cause.

  19. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Michael D. Blanton


    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  20. CPI Challenges CHINALCO in Aluminum Business

    Institute of Scientific and Technical Information of China (English)


    <正>China Power Investment Corporation (hereinafter referred to as CPI),one of the top 5 power generation groups,grows rapidly in aluminum business,making CHINALCO (hereinafter re-ferred to as CHINALCO),the traditional No.1

  1. Inelastic Deformation Analysis of Aluminum Bending Members

    Institute of Scientific and Technical Information of China (English)

    CHENG Ming; SHI Yongjiu; WANG Yuanqing


    Aluminum alloys are typical nonlinear materials, and consequently bending members made of this material exhibit a nonlinear behavior. Most design codes do not pay much attention to such deformations and adopt a simple linear analysis for the calculation of deflections. This paper presents an investigation of the nonlinear deformation of aluminum bending members using the finite-element analysis (FEA). The plastic adaptation coefficient, which can be used to limit the residual deflection, is introduced, and the influence of residual deflection is investigated. A method for evaluating the plastic adoption coefficient is proposed. This paper also shows the load-deflection curve of aluminum bending members and the influence of several parameters. A semi-empirical formula is derived, and some numerical examples are given by FEA. The coefficients of the semi-empirical formula are modified by the FEA results using the nonlinear fitting method. Based on these results, two improved design methods for strength and deformation of aluminum bending members are proposed. Through the comparison with test data, these methods are proved to be suitable for structural design.

  2. 75 FR 80527 - Aluminum Extrusions From China (United States)


    ... Republic of China: Postponement of Final Determination of Sales at Less Than Fair Value, 75 FR 73041... Sales at Less Than Fair Value, and Preliminary Determination of Targeted Dumping, 75 FR 69403, November... Affirmative Countervailing Duty Determination, 75 FR 54302, September 7, 2010, and Aluminum Extrusions...

  3. Absorptive coating for aluminum solar panels (United States)

    Desmet, D.; Jason, A.; Parr, A.


    Method for coating forming coating of copper oxide from copper component of sheet aluminum/copper alloy provides strong durable solar heat collector panels. Copper oxide coating has solar absorption characteristics similar to black chrome and is much simpler and less costly to produce.

  4. Molybdate Coatings for Protecting Aluminum Against Corrosion (United States)

    Calle, Luz Marina; MacDowell, Louis G.


    Conversion coatings that comprise mixtures of molybdates and several additives have been subjected to a variety of tests to evaluate their effectiveness in protecting aluminum and alloys of aluminum against corrosion. Molybdate conversion coatings are under consideration as replacements for chromate conversion coatings, which have been used for more than 70 years. The chromate coatings are highly effective in protecting aluminum and its alloys against corrosion but are also toxic and carcinogenic. Hexavalent molybdenum and, hence, molybdates containing hexavalent molybdenum, have received attention recently as replacements for chromates because molybdates mimic chromates in a variety of applications but exhibit significantly lower toxicity. The tests were performed on six proprietary formulations of molybdate conversion coatings, denoted formulations A through F, on panels of aluminum alloy 2024-T3. A bare alloy panel was also included in the tests. The tests included electrochemical impedance spectroscopy (EIS), measurements of corrosion potentials, scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS).

  5. High Energy Density aluminum/oxygen cell (United States)

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  6. Friction Stir Welding of Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    FU Zhi-hong; HE Di-qiu; WANG Hong


    Friction stir welding(FSW), a new solid-state welding technology invited in the early 1990s,enables us weld aluminum alloys and titanium alloys etc. The processing of FSW, the microstructure in FSW alloysand the factors influencing weld quality are introduced. The complex factors affecting the properties are researched.

  7. Laser micro welding of copper and aluminum (United States)

    Mys, Ihor; Schmidt, Michael


    Aluminum combines comparably good thermal and electrical properties with a low price and a low material weight. These properties make aluminum a promising alternative to copper for a large number of electronic applications, especially when manufacturing high volume components. However, a main obstacle for a wide use of this material is the lack of a reliable joining process for the interconnection of copper and aluminum. The reasons for this are a large misalignment in the physical properties and even more a poor metallurgical affinity of both materials that cause high crack sensitivity and the formation of brittle intermetallic phases during fusion welding. This paper presents investigations on laser micro welding of copper and aluminum with the objective to eliminate brittle intermetallic phases in the welding structure. For these purposes a combination of spot welding, a proper beam offset and special filler material are applied. The effect of silver, nickel and tin filler materials in the form of thin foils and coatings in a thickness range 3-100 μm has been investigated. Use of silver and tin filler materials yields to a considerable improvement of the static and dynamic mechanical stability of welded joints. The analysis of the weld microstructure shows that an application even of small amounts of suitable filler materials helps to avoid critical, very brittle intermetallic phases on the interface between copper and solidified melt in the welded joints.

  8. UV fluorescence enhancement from nanostructured aluminum materials (United States)

    Montanari, Danielle E.; Dean, Nathan; Poston, Pete E.; Blair, Steve; Harris, Joel M.


    Interest in label-free detection of biomolecules has given rise to the need for UV plasmonic materials. DNA bases and amino acid residues have electronic resonances in the UV which allow for sensitive detection of these species by surface-enhanced UV fluorescence spectroscopy. Electrochemical roughening has been used extensively to generate plasmonically-active metal surfaces that produce localized enhancement of excitation and emission of electromagnetic radiation from surface-bound molecules. Electrochemically roughened gold and silver surfaces produce enhancement in the visible and near-IR regions, but to the best of our knowledge, application of this technique for producing UV-enhancing substrates has not been reported. Using electropolishing of aluminum, we are able to generate nanostructured surfaces that produce enhanced spectroscopic detection of molecules in the UV. Aluminum is a natural choice for substrate composition as it exhibits a relatively large quality factor in the UV. We have fabricated electropolished aluminum films with nanometer scale roughness and have studied UV-excited fluorescence enhancement from submonolayer coverage of tryptophan on these substrates using a UV-laser based spectrometer. Quantitative dosing by dip-coating was used to deposit known surface concentrations of the aromatic amino acid tryptophan, so that fluorescence enhancement could be evaluated. Compared to a dielectric substrate (surface-oxidized silicon), we observe a 180-fold enhancement in the total fluorescence emitted by tryptophan on electropolished aluminum under photobleaching conditions, allowing detection of sub-monolayer coverages of molecules essential for development of biosensor technologies.

  9. Low absorptance porcelain-on-aluminum coating (United States)

    Leggett, H.


    Porcelain thermal-control coating for aluminum sheet and foil has solar absorptance of 0.22. Specially formulated coating absorptance is highly stable, changing only 0.03 after 1,000 hours of exposure to simulated sunlight and can be applied by standard commercial methods.

  10. Optical properties of ALON (aluminum oxynitride) (United States)

    Hartnett, T. M.; Bernstein, S. D.; Maguire, E. A.; Tustison, R. W.


    The optical properties of ALON (aluminum oxynitride) are presented. Optical scatter and index of refraction, and absorption of several different compositions of ALON are compared. The temperature dependence of emissivity of ALON was measured in the temperature range 46°C to 1200°C.

  11. Performance Evaluation Tests of Insulated Pressure Vessels for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Martinez-Frias, J; Espinoza-Loza, F


    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests have been conducted, and the results indicate that no significant vessel damage has resulted from cryogenic operation. Future activities include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for certification of insulated pressure vessels.

  12. Certification Testing and Demonstration of Insulated Pressure Vessels for Vehicular Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Aceves, S M; Martinez-Frias, J; Espinosa-Loza, F


    Insulated pressure vessels are cryogenic-capable pressure vessels that can be fueled with liquid hydrogen or ambient-temperature compressed hydrogen. This flexibility results in multiple advantages with respect to compressed hydrogen tanks or low-pressure liquid hydrogen tanks. Our work is directed at verifying that commercially available aluminum-lined, fiber-wrapped pressure vessels can be safely used to store liquid hydrogen. A series of tests have been conducted, and the results indicate that no significant vessel damage has resulted from cryogenic operation. Future activities include a demonstration project in which the insulated pressure vessels will be installed and tested on two vehicles. A draft standard will also be generated for certification of insulated pressure vessels.

  13. Hydrogen Storage Materials for Mobile and Stationary Applications: Current State of the Art. (United States)

    Lai, Qiwen; Paskevicius, Mark; Sheppard, Drew A; Buckley, Craig E; Thornton, Aaron W; Hill, Matthew R; Gu, Qinfen; Mao, Jianfeng; Huang, Zhenguo; Liu, Hua Kun; Guo, Zaiping; Banerjee, Amitava; Chakraborty, Sudip; Ahuja, Rajeev; Aguey-Zinsou, Kondo-Francois


    One of the limitations to the widespread use of hydrogen as an energy carrier is its storage in a safe and compact form. Herein, recent developments in effective high-capacity hydrogen storage materials are reviewed, with a special emphasis on light compounds, including those based on organic porous structures, boron, nitrogen, and aluminum. These elements and their related compounds hold the promise of high, reversible, and practical hydrogen storage capacity for mobile applications, including vehicles and portable power equipment, but also for the large scale and distributed storage of energy for stationary applications. Current understanding of the fundamental principles that govern the interaction of hydrogen with these light compounds is summarized, as well as basic strategies to meet practical targets of hydrogen uptake and release. The limitation of these strategies and current understanding is also discussed and new directions proposed.

  14. Atomic, electronic, and magnetic properties of bimetallic ZrCo clusters: A first-principles study (United States)

    Chattaraj, D.; Bhattacharya, Saswata; Dash, Smruti; Majumder, C.


    Here, we report the atomic, electronic, and magnetic structures of small ZrmCon (m + n = 2, 4, 6, and 8) alloy clusters based on spin-polarized density functional theory under the plane wave based pseudo-potential approach. The ground state geometry and other low-lying stable isomers of each cluster have been identified using the cascade genetic algorithm scheme. On the basis of the relative energy, it is found that Zr2Co2 (for tetramer), Zr3Co3 (for hexamer), and Zr4Co4 (for octamer) are the most stable isomers than others. In order to underscore the hydrogen storage capacity of these small clusters, the hydrogen adsorption on the stable ZrmCon (m + n = 2, 4, 6, and 8) clusters has also been studied. The electronic structures of ZrmCon clusters with and without adsorbed hydrogen are described in terms of density of states spectra and charge density contours.

  15. Hydrogen-Bonding Surfaces for Ice Mitigation (United States)

    Smith, Joseph G., Jr.; Wohl, Christopher J.; Kreeger, Richard E.; Hadley, Kevin R.; McDougall, Nicholas


    Ice formation on aircraft, either on the ground or in-flight, is a major safety issue. While ground icing events occur predominantly during the winter months, in-flight icing can happen anytime during the year. The latter is more problematic since it could result in increased drag and loss of lift. Under a Phase I ARMD NARI Seedling Activity, coated aluminum surfaces possessing hydrogen-bonding groups were under investigation for mitigating ice formation. Hydroxyl and methyl terminated dimethylethoxysilanes were prepared via known chemistries and characterized by spectroscopic methods. These materials were subsequently used to coat aluminum surfaces. Surface compositions were based on pure hydroxyl and methyl terminated species as well as mixtures of the two. Coated surfaces were characterized by contact angle goniometry. Receding water contact angle data suggested several potential surfaces that may exhibit reduced ice adhesion. Qualitative icing experiments performed under representative environmental temperatures using supercooled distilled water delivered via spray coating were inconclusive. Molecular modeling studies suggested that chain mobility affected the interface between ice and the surface more than terminal group chemical composition. Chain mobility resulted from the creation of "pockets" of increased free volume for longer chains to occupy.

  16. Aluminum Foil and Aluminum Sheet Project with the Total Investment of RMB 1 billion Officially Launched in Wanshan

    Institute of Scientific and Technical Information of China (English)


    <正>According the news report on February 25,Wanshan district and Galaxy Aluminum Co.,Ltd. in Shengzhou,Zhejiang province signed an agreement on aluminum foil and aluminum sheet production on February 19 in Sanya,Hainan province,a sign that the project is offi- cially established in Wanshan.

  17. Hangzhou Jinjiang Group Shanxi Fusheng Aluminum Phase I 800,000 t/a Aluminum Oxide Project Started Operation

    Institute of Scientific and Technical Information of China (English)


    <正>On October 19,the Shanxi Province Pinglu County Phase I 800,000t/a Aluminum Oxide Project of Shanxi Fusheng Aluminum Co.,Ltd,a subordinate of Hangzhou Jinjiang Group,started operation.This is the fourth Aluminum oxide project constructed and operated by Jinjiang Group.

  18. Interaction of Boron Clusters with Oxygen: a DFT Study (United States)

    Salavitabar, Kamron; Boggavarapu, Kiran; Kandalam, Anil

    A controlled combustion involving aluminum nanoparticles has often been the focus of studies in the field of solid fuel propellants. However very little focus has been given to the study of boron nanoparticles in controlled combustion. In contrast to aluminum nanoclusters, boron nanoclusters (Bn) are known to exhibit a planar geometries even at the size of n = 19 - 20, and thus offer a greater surface area for interaction with oxygen. Earlier experimental studies have shown that boron nanoclusters exhibit different reactivity with oxygen depending on their size and charge. In this poster, we present our recent density functional theory based results, focusing on the reactivity patterns of neutral and negatively charged B5 cluster with On, where n = 1 - 5; and B6 cluster with On (n = 1 - 2). The effect of charge on the reactivity of boron cluster, variation in the stability of product clusters, i e., neutral and negatively charged B5On (n = 1 - 5) and B6On (n = 1 - 2) are also examined. Financial Support from West Chester University Foundation under FaStR grant is acknowledged.

  19. Investigation of Methods for Selectively Reinforcing Aluminum and Aluminum-Lithium Materials (United States)

    Bird, R. Keith; Alexa, Joel A.; Messick, Peter L.; Domack, Marcia S.; Wagner, John A.


    Several studies have indicated that selective reinforcement offers the potential to significantly improve the performance of metallic structures for aerospace applications. Applying high-strength, high-stiffness fibers to the high-stress regions of aluminum-based structures can increase the structural load-carrying capability and inhibit fatigue crack initiation and growth. This paper discusses an investigation into potential methods for applying reinforcing fibers onto the surface of aluminum and aluminum-lithium plate. Commercially-available alumina-fiber reinforced aluminum alloy tapes were used as the reinforcing material. Vacuum hot pressing was used to bond the reinforcing tape to aluminum alloy 2219 and aluminum-lithium alloy 2195 base plates. Static and cyclic three-point bend testing and metallurgical analysis were used to evaluate the enhancement of mechanical performance and the integrity of the bond between the tape and the base plate. The tests demonstrated an increase in specific bending stiffness. In addition, no issues with debonding of the reinforcing tape from the base plate during bend testing were observed. The increase in specific stiffness indicates that selectively-reinforced structures could be designed with the same performance capabilities as a conventional unreinforced structure but with lower mass.

  20. Scandinavian hydrogen highway partnership

    Energy Technology Data Exchange (ETDEWEB)

    Sloth, M.; Hansen, J. [H2 Logic A/S, Herning (Denmark); Wennike, F. [Hydrogen Link Denmark Association, Ringkoebing (Denmark)


    The Scandinavian Hydrogen Highway Partnership (SHHP) was launched in an effort to build hydrogen filling stations in Scandinavian countries by 2012 in order to enable hydrogen powered vehicles to operate and refuel when needed. Three hydrogen refueling stations are currently in operation in Scandinavia to fuel a fleet of 15 hydrogen-fuelled cars. It is anticipated that by the end of 2009, there will be 14 hydrogen refueling stations and more than 70 vehicles in operation. Beyond 2012, the number of filling stations and vehicles is expected to increase significantly through large scale demonstration, where SHHP aims to attract funding from the European Union. The current activities of SHHP are co-funded by national and regional authorities. The SHHP network is funded by Nordic Energy Research.