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Sample records for al europhys lett

  1. Comment on: "The ascent of kimberlite: Insights from olivine" by Brett R.C. et al. [Earth Planet. Sci. Lett. 424 (2015) 119-131

    NASA Astrophysics Data System (ADS)

    Kamenetsky, Vadim S.

    2016-04-01

    Brett et al. (2015) proposed a kimberlite factory model that ;…involves carbonatitic proto-kimberlite melts preferentially assimilating Opx xenocrysts as they transit the cratonic mantle lithosphere to evolve into silicic-hydrous melts that reach olivine saturation during ascent; (p. 130). A cornerstone of this model is a specific, carbonatitic composition of proto-kimberlite melts ascending through the subcratonic lithospheric mantle ;…whereby parental carbonatitic magmas are progressively converted to kimberlite (e.g., Russell et al., 2012, 2013; Bussweiler et al., 2015); (p. 120). The model by Brett et al. (2015) is based on observations of ;the carbonate-sealed cracks; in olivine that ;…strongly support to the hypothesis that all kimberlite magmas originate as carbonatitic-melts (e.g., Russell et al., 2012, 2013; Kamenetsky et al., 2013; Pilbeam et al., 2013; Kamenetsky and Yaxley, 2015; Bussweiler et al., 2015).; (p. 129). While the major thrust of the study by Brett et al. (2015) hinges on the premise that the parental kimberlite melt is carbonatitic, the overwhelming majority in the kimberlite community still prefers a carbonated ultramafic/ultrabasic composition for parental kimberlite melts. Thus the suggestion that kimberlites have an initial carbonatite composition is not less than ;a paradigm shift; in the kimberlite petrology. It appears that a carbonatite origin for kimberlites has been proposed in many studies that significantly pre-date the publications starting from 2012 that they cite, but which unfortunately are overlooked by Brett et al. (2015). It is, therefore, worth acknowledging the research which has previously advanced this unorthodox idea.

  2. Reply on: "Comment on: The ascent of kimberlite: Insights from olivine" authored by Brett R.C. et al. [Earth Planet. Sci. Lett. 424 (2015) 119-131

    NASA Astrophysics Data System (ADS)

    Brett, R. Curtis; Russell, J. K.; Andrews, G. D. M.; Jones, T. J.

    2016-04-01

    The Kamenetsky (2016) comment on the Kimberlite Factory model proposed by Brett et al. (2015) asserts, ;A cornerstone of this model is a specific, carbonatitic composition of proto-kimberlite melts ascending through the sub-cratonic lithospheric mantle; and ;… the major thrust of the study hinges on the premise that the parental kimberlite melt is carbonatitic;. This is a clear misstatement of our central thesis, which is to utilize the attributes of olivine xenocrysts to constrain the physical ascent of kimberlite. Brett et al.'s study does not hinge on the premise that parental kimberlite melt is carbonatitic. Rather, our interpretation that kimberlite melt originates as near carbonatitic hinges on our novel observation that early ;carbonate sealed cracks provide evidence of melt being drawn into decompression cracks and precipitating; (p. 129). Our connection between this observation and our interpretation is tied explicitly to earlier published works ;in this regard, the carbonate-filled sealed cracks strongly support to the hypothesis that all kimberlite magmas originate as carbonatitic-melts (e.g.,Russell et al., 2012, 2013;Kamenetsky et al., 2013; Pilbeam et al., 2013; Kamenetsky and Yaxley, 2015; Bussweiler et al., 2015); (p. 129). To state that our interpretation is based on a pre-existing bias towards a model of a carbonatitic origin of kimberlite magmas is incorrect. Rather, our new observational data independently demonstrates that the presence of carbonate-sealed cracks formed during kimberlite ascent.

  3. Reply to Comment on: “Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event”, by P. Vannucchi et al. [Earth Planet. Sci. Lett. 409 (2015) 168-174

    NASA Astrophysics Data System (ADS)

    Vannucchi, Paola; Morgan, Jason P.

    2015-06-01

    The comment by Schmieder et al. (in press) concentrates on the viability of the quartz planar microdeformation features (PMFs) (or deformation lamellae) presented by Vannucchi et al. (2015) to infer the presence of shock metamorphism in the area of the 1908 Tunguska event. Their comment focuses on two points: The quartz PMFs that are shown in Vannucchi et al. are not produced by shock metamorphism.

  4. Comment on: “Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event”, by P. Vannucchi et al. [Earth Planet. Sci. Lett. 409 (2015) 168-174

    NASA Astrophysics Data System (ADS)

    Schmieder, Martin; Ferrière, Ludovic; Ormö, Jens; Buchner, Elmar; Koeberl, Christian; Reimold, Wolf Uwe

    2015-06-01

    Vannucchi et al. (2015) report alleged 'shock metamorphic' features in Permian sandstone clasts associated with the Siberian Trap basalts at Mount Stojkovic inside the Great Tunguska Depression, only a few kilometers away from the site of the 1908 Tunguska event. Given the low probability that these features have formed by either the Tunguska event or by an older impact in the same area, Vannucchi et al. argue that these features may in fact not be diagnostic for impact, but could also be related to explosive volcanism.

  5. Reply to comment on "Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event" by Vannucchi et al. (Earth Planet. Sci. Lett. 409 (2015) 168-174)

    NASA Astrophysics Data System (ADS)

    Vannucchi, Paola; Morgan, Jason P.

    2015-04-01

    Our paper (Vannucchi et al., 2015) focuses on geologic evidence for shock metamorphism found at the epicentral region of the 1908 Tunguska event. None of the currently proposed bolide explanations for the 1908 event can produce the shock pressures indicated by the geological evidence described in Vannucchi et al. (2015). If the 1908 event would have generated these pressures over the epicentral region, an observable crater should have also formed. The comment by Melott and Overholt discusses the possibility that a 1908 cometary bolide strike in Tunguska cannot be excluded because of the absence of a detectable 14C increase at this site. They dispute the findings of a recent Liu et al.'s (2014) study that an East Asian comet impact recorded by eyewitness accounts in 773 AD was coincident with a detectable 14C increase in regional South China Sea corals that grew at that time. Their point, whether true or not, is fairly peripheral to our study because the bolide hypothesis for the 1908 Tunguska event, no matter the nature of the bolide itself, does not provide a viable explanation for the geological evidence of shock metamorphism found at the 1908 Tunguska site. Furthermore, as we discuss in our paper, the probability of a prior large impact-shock event having occurred at the site of the 1908 event is extremely low, suggesting that a terrestrial shock-generating mechanism may be linked to the resolution of the Tunguska enigma. Our preferred resolution is that a terrestrial hyper-explosive gas release event, a Verneshot (Morgan et al., 2004), created the large shock-event during the emplacement of the Siberian Traps. In this scenario, the 1908 Tunguska event was due to a much smaller gas-burst that re-used the lithospheric weakness created by the ancient Verneshot. Melott and Overholt's discussion regarding the existence and size of regional and global 14C anomalies related to cometary impacts seems, therefore, to be better addressed in response to the work of Liu et

  6. Comment on "Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event" by Vannucchi et al. (Earth Planet. Sci. Lett. 409 (2015) 168-174)

    NASA Astrophysics Data System (ADS)

    Melott, Adrian L.; Overholt, Andrew C.

    2015-04-01

    An enormous explosion, reportedly aerial, over Tunguska, Siberia in 1908 is commonly thought to be a bolide of some type, possibly a rocky or metallic asteroid, or an icy comet. Vannucchi et al. (2015) present a variety of arguments against the bolide hypothesis. They argue that the lack of unambiguous meteoritic material in the area excludes rocky or metallic asteroids, and that the lack of a 14C anomaly in the geoisotope record excludes a comet. They then present evidence of shock metamorphism in the area which they attribute to a volcanic superexplosion. We show here that the exclusion of a comet based on the isotopic record and the work of Liu et al. (2014) is incorrect.

  7. Comment on “40Ar / 39Ar dating of the Rajahmundry Traps, eastern India and their relationship to the Deccan Traps” by Knight et al. [Earth Planet Sci. Lett. 208 (2003) 85 99

    NASA Astrophysics Data System (ADS)

    Baksi, Ajoy K.

    2005-11-01

    Knight et al. presented age and chemical data on two (sets of) lava flows from the Rajahmundry area, on either bank of the Godavari River. The age and petrogenesis of these flows and their possible link to sections of the main Deccan Province are of importance to the understanding of many aspects of flood basalt volcanism. I comment on (a) the use of geochemical fingerprints for lava identification/correlation at Rajahmundry, superceding (apparent) field relations, (b) their 40Ar / 39Ar data and its refinement based on statistical tests and the alteration state of the samples (c) correlation of age data and the magnetic polarity of the lavas to the geomagnetic polarity time scale and (d) the possibility that both lavas at Rajahmundry were formed by intracanyon flows derived from ˜1000 km away.

  8. Comment on “Isotopic fractionation between Fe(III) and Fe(II) in aqueous solutions” by Clark Johnson et al., [Earth Planet. Sci. Lett. 195 (2002) 141–153

    USGS Publications Warehouse

    Bullen, Thomas D.; White, Arthur F.; Childs, Cyril W.

    2003-01-01

    In a recent contribution [1], Johnson et al. reported the equilibrium isotope fractionation factor between dissolved Fe(II) and Fe(III) in aqueous solutions at pH=2.5 and 5.5. They suggest that because the iron isotope fractionation observed in their experiments spans virtually the entire range observed in sedimentary rocks, Fe(II)–Fe(III) aqueous speciation may play a major role in determining iron isotope variations in nature where Fe(II) and Fe(III) can become physically separated. They discounted earlier conclusions by us and others [2] ;  [3] that significant equilibrium fractionation between specific coexisting Fe(II)- or Fe(III)-aqueous complexes (e.g., between aqueous Fe(II)(OH)x(aq)and Fe(II)(aq) ion) is capable of producing iron isotope contrasts that can be preserved in nature. This is an important contribution not only because the authors recognize the importance of abiotic equilibrium iron isotope fractionation in nature in contrast to previous assertions [4], but also because it will help to focus discussion on the development and evaluation of experimental approaches that can reveal abiotic fractionation mechanisms. However, in this Comment we propose that the experiments presented in this paper cannot be interpreted as straightforwardly as Johnson et al. contend. In particular, we show that in one of their critical experiments attainment of either isotope mass balance or equilibrium was not demonstrated, and thus the results of that experiment cannot be used to calculate an Fe(II)–Fe(III) equilibrium fractionation factor.

  9. Al2O3 nanocrystals embedded in amorphous Lu2O3 high-k gate dielectric for floating gate memory application

    NASA Astrophysics Data System (ADS)

    Yuan, C. L.; Chan, M. Y.; Lee, P. S.; Darmawan, P.; Setiawan, Y.

    2007-04-01

    The integration of nanoparticles has high potential in technological applications and opens up possibilities of the development of new devices. Compared to the conventional floating gate memory, a structure containing nanocrystals embedded in dielectrics shows high potential to produce a memory with high endurance, low operating voltage, fast write-erase speeds and better immunity to soft errors [S. Tiwari, F. Rana, H. Hanafi et al. 1996 Appl.Phys. Lett. 68, 1377]. A significant improvement on data retention [J. J. Lee, X. Wang et al. 2003 Proceedings of the VLSI Technol. Symposium, p33] can be observed when discrete nanodots are used instead of continuous floating gate as charge storage nodes because local defect related leakage can be reduced efficiently. Furthermore, using a high-k dielectric in place of the conventional SiO2 based dielectric, nanodots flash memory is able to achieve significantly improved programming efficiency and data retention [A. Thean and J. -P. Leburton, 2002 IEEE Potentials 21, 35; D. W. Kim, T. Kim and S. K. Banerjee, 2003 IEEE Trans. Electron Devices 50, 1823]. We have recently successfully developed a method to produce nanodots embedded in high-k gate dielectrics [C. L. Yuan, P. Darmawan, Y. Setiawan and P. S. Lee, 2006 Electrochemical and Solid-State Letters 9, F53; C. L. Yuan, P. Darmawan, Y. Setiawan and P. S. Lee, 2006 Europhys. Lett. 74, 177]. In this paper, we fabricated the memory structure of Al2O3 nanocrystals embedded in amorphous Lu2O3 high k dielectric using pulsed laser ablation. The mean size and density of the Al2O3 nanocrystals are estimated to be about 5 nm and 7x1011 cm-2, respectively. Good electrical performances in terms of large memory window and good data retention were observed. Our preparation method is simple, fast and economical.

  10. Comment on: “Quantum exam” [Phys. Lett. A 350 (2006) 174

    NASA Astrophysics Data System (ADS)

    Song, Jie; Zhang, Shou

    2007-01-01

    In the Letter [B.A. Nguyen, Phys. Lett. A 350 (2006) 174], a quantum exam protocol was presented. Here we show a cheating protocol, by which any student can get the other students' solution without being detected. Then we propose a possible modified protocol against this attacking strategy.

  11. Comment on ``Three-dimensional photonic-crystal emitter for thermal photovoltaic power generation'' [Appl. Phys. Lett. 83, 380 (2003)

    NASA Astrophysics Data System (ADS)

    Trupke, Thorsten; Würfel, Peter; Green, Martin A.

    2004-03-01

    In a recent article, Lin et al. [Appl. Phys. Lett. 83, 380 (2003)] reported on the light-emitting properties of three-dimensional tungsten photonic crystals and their potential applications as improved thermal emitters in thermophotovoltaic (TPV) systems. Their findings have attracted considerable interest throughout the media and the application of this type of materials has been praised as a potential superior future energy source; e.g., in waste heat-driven electrical generators (http://www.photonics.com). The results of the theoretical modeling in the work of Lin et al. suggest that a TPV system can achieve higher heat to electric energy conversion efficiencies in combination with a three-dimensional tungsten photonic crystal than with any conventional selective thermal emitter. These theoretical results are based on the experimental observation that the photonic crystal, when heated to a given temperature, emits more radiation in certain spectral regimes than a black body of the same temperature. This experimental observation shall briefly be discussed here.

  12. Comment on 'Thermodynamic cycles and the calculation of p Ka' [Chem. Phys. Lett. 367 (2003) 145

    NASA Astrophysics Data System (ADS)

    da Silva, Clarissa O.; da Silva, Edilson C.; Nascimento, Marco A. C.

    2003-11-01

    In a recent Letter, Pliego [Chem. Phys. Lett. 367 (2003) 145] has raised some questions about the methodology that we have employed for calculating p Ka values in aqueous solutions. In this comment we show that the problem with Pliego's analysis is the fact that he used Ben-Naim's definition of Δ Gsol for both the solute and the solvent, which implies that the concentration, for both components, should be equal to 1 M. For the solute, this is a reference state fully compatible with the quantum description, but for the solvent this choice is unphysical, as discussed in the Letter.

  13. Comment on ‘To stack or not to stack: Performance of a new density functional for the uracil and thymine dimers’ [Chem. Phys. Lett. 459 (2008) 164

    NASA Astrophysics Data System (ADS)

    van Mourik, Tanja

    2009-04-01

    A Letter by Gu et al. [J. Gu, J. Wang, J. Leszczynski, Y. Xie, H.F. Schaefer III, Chem. Phys. Lett. 459 (2008) 164] presented MP2/6-31+G(d) and MP2/TZVPP stacking energies for the uracil and thymine dimers, with the aim to assess the performance of the new M06-2X density functional. However, the stacking energies were not corrected for the basis set superposition error (BSSE). Here we show that correction for this error dramatically changes the results. BSSE correction severely reduces the stacking energy of the thymine dimer, whereas the stacked uracil dimer structure considered by Gu et al. is not even a minimum on the MP2/6-31+G(d) potential energy surface.

  14. Intermittency in two-dimensional Ekman-Navier-Stokes turbulence

    NASA Astrophysics Data System (ADS)

    Boffetta, G.; Celani, A.; Musacchio, S.; Vergassola, M.

    2002-08-01

    We study the statistics of the vorticity field in two-dimensional Navier-Stokes turbulence with linear Ekman friction. We show that the small-scale vorticity fluctuations are intermittent, as conjectured by Bernard [Europhys. Lett. 50, 333 (2000)] and Nam et al. [Phys. Rev. Lett. 84, 5134 (2000)]. The small-scale statistics of vorticity fluctuations coincide with that of a passive scalar with finite lifetime transported by the velocity field itself.

  15. Erratum to "Multi-modal fission in collinear ternary cluster decay of 252Cf(sf,fff)" [Phys. Lett. B 746 (2015) 223

    NASA Astrophysics Data System (ADS)

    von Oertzen, W.; Nasirov, A. K.; Tashkodjaev, R. B.

    2016-11-01

    The scale of the ordinate axis of Fig. 4 on page 226 of PLB 746 (2015) 223 was incorrect. The new version of Fig. 4 (which is "Fig. 1" in the present note) with the correct ordinate axis is given here (upper part). The lower part shows the previous version. Five potential wells and barriers are shown. Considering a sequential process two barriers are relevant for the decay, with equal barriers for the symmetric cases with a smaller fragment at the center (in these cases only one barrier is shown). For the asymmetric case of 70Ni + 50Ca + 132Sn, two different barriers appear, denoted as (B1) and (B2), which correspond to the interactions of the middle cluster 50Ca with the outer nuclei 70Ni and 132Sn, respectively. In a sequential mechanism the separation of 132Sn from the other part via the barrier B2 having the smaller height, is favoured for the first step. For the second step the barrier (B1) between Ni and Ca, appears at smaller distances (dot-dashed curve) and is higher. The order of the barriers of the five channels is unchanged, compared to the figure in Ref. W. von Oertzen et al., Phys. Lett. B 746 (2015) 223.

  16. Corrigendum to "Multi-modal Fission in Collinear Ternary Cluster decay of 252Cf(sf,fff)" [Phys. Lett. B 746 (2015) 223

    NASA Astrophysics Data System (ADS)

    von Oertzen, W.; Nasirov, A. K.; Tashkodjaev, R. B.

    2017-02-01

    The scale of the ordinate axis of Fig. 4 on page 226 of PLB 746 (2015) 223 was incorrect. The new version of Fig. 4 (which is "Fig. 1" in the present note) with the correct ordinate axis is given here (upper part). The lower part shows the previous version. Five potential wells and barriers are shown. Considering a sequential process, two barriers are relevant for the sequential decay, with equal barriers for the symmetric cases with a smaller fragment at the center (in these cases only one barrier is shown). For the asymmetric case of 70Ni + 50Ca + 132Sn, two different barriers appear, denoted as (B1) and (B2), which correspond to the interactions of the middle cluster 50Ca with the outer nuclei 70Ni and 132Sn, respectively. In a sequential mechanism the separation of 132Sn from the other part via the barrier B2 has the smaller height, thus it is favored for the first step. For the second step the barrier (B1) between Ni and Ca, appears at smaller distances (dot-dashed curve) and is higher. The order of the barriers of the five channels is unchanged, compared to the figure in Ref. W. von Oertzen et al., Phys. Lett. B 746 (2015) 223.

  17. Comment on “Deterministic six states protocol for quantum communication” [Phys. Lett. A 358 (2006) 85

    NASA Astrophysics Data System (ADS)

    El-Orany, Faisal A. A.

    2010-02-01

    In [J.S. Shaari, M. Lucamarini, M.R.B. Wahiddin, Phys. Lett. A 358 (2006) 85] the deterministic six states protocol (6DP) for quantum communication has been developed. This protocol is based on three mutually unbiased bases and four encoding operators. Information is transmitted between the users via two qubits from different bases. Three attacks have been studied; namely intercept-resend attack (IRA), double-CNOT attack (2CNOTA) and quantum man-in-the-middle attack. In this Letter, we show that the IRA and 2CNOTA are not properly addressed. For instance, we show that the probability of detecting Eve in the control mode of the IRA is 70% instead of 50% in the previous study. Moreover, in the 2CNOTA, Eve can only obtain 50% of the data not all of it as argued earlier.

  18. Comment on: “From classical to modern ether-drift experiments: the narrow window for a preferred frame” [Phys. Lett. A 333 (2004) 355

    NASA Astrophysics Data System (ADS)

    Guerra, Vasco; de Abreu, Rodrigo

    2007-02-01

    In a recent article [M. Consoli, E. Costanzo, Phys. Lett. A 333 (2004) 355], M. Consoli and E. Costanzo have investigated classical and modern aether drift experiments and explored the narrow window for detection of a preferred reference frame. This Letter proposes an easy to perform variant of Fizeau's experiment, which may confirm or deny Consoli Costanzo's claims.

  19. Bierman {ital et al.}Reply:

    SciTech Connect

    Bierman, J.D.; Chan, P.; Liang, J.F.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R.

    1997-05-01

    reply to the Comment by C.H.Dasso et al., Phys. Rev. Lett. 78,XXX(1997). A Reply to the Comment by C.H. Dasso and J. Fern{acute a}ndez-Niello. {copyright} {ital 1997} {ital The American Physical Society}

  20. Current Collapse Induced in AlGaN/GaN High-Electron-Mobility Transistors by Bias Stress

    DTIC Science & Technology

    2003-08-25

    structure where the traps causing current collapse can be passivated by forming H-defect complexes. Hierro et al.7 have shown, for example, that deep...Lett. 75, 4016 ~1999!. 7 A. Hierro , S. A. Ringel, M. Hansen, J. S. Speck, U. K. Mishra, and S. P. DenBaars, Appl. Phys. Lett. 77, 1499 ~2000!. 8 S. J

  1. Comments on “Thermal relic abundances of particles with velocity-dependent interactions” [Phys. Lett. B 687 (2010) 275

    NASA Astrophysics Data System (ADS)

    Iminniyaz, Hoernisa

    2013-06-01

    We reexamine the effect of kinetic decoupling on the relic density of the non-relativistic particles whose annihilation rate is increased by Sommerfeld enhancement. I claim that the result in Dent et al. (2010) [1] is wrong in the case of kinetic decoupling for small coupling constant α.

  2. High-order power series expansion of the elastic interaction between conical membrane inclusions.

    PubMed

    Fournier, Jean-Baptiste; Galatola, Paolo

    2015-08-01

    We revisit the problem of the long-range interaction between two conical proteins inserted into a lipid membrane and interacting via the induced deformation of the membrane, first considered by Goulian et al. (M. Goulian, R. Bruinsma, P. Pincus, Europhys. Lett. 22, 145 (1993); Europhys. Lett. 23, 155 (1993)). By means of a complex variables formulation and an iterative solution, we determine analytically an arbitrary high-order expansion of the interaction energy in powers of the inverse distance between two inclusions of different sizes. At leading order and for inclusions of equal sizes, we recover the result obtained by Goulian et al.. We generalize the development to inclusions of different sizes and give explicit formulas that increase the precision by ten orders in the inverse distance.

  3. A multifractality analysis of Ising financial markets with small world topology

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Li, Xue

    2015-03-01

    Following our preceding study [H. Zhao et al., Europhys. Lett. 101, 18001 (2013)], in which a self-organizing Ising-like model of artificial financial markets with underlying small world (SW) network topology was investigated, we continue to proceed a multifractal analysis of the price dynamics of the model in current paper. We find that the price return exhibits multifractal property. This suggests that our Ising-like model reproduces the major stylized facts of real world financial markets.

  4. Comment on “Scaling behavior of one-dimensional Pt chains migration on Pt(110)-(1×2) surface”. [Phys. Lett. A 268 (2000) 413

    NASA Astrophysics Data System (ADS)

    Montalenti, F.; Ferrando, R.

    2000-11-01

    We show that the recently proposed scaling laws [see G. Zhuang, W. Wang, Phys. Lett. A 268 (2000) 413] for chain diffusion on missing-row Pt(110) have no real meaning, since they cannot be extended outside the narrow chain-length range which has been considered by Zhuang and Wang. The only asymptotic scaling law gives a chain mobility which is inversely proportional to the chain length; however this asymptotic scaling behaviour is not physically important due to the occurrence of multiple upward promotions for long chains.

  5. Preparation of Entangled Polymer Melts of Various Architecture for Coarse-Grained Models

    DTIC Science & Technology

    2011-09-01

    thermostat, see the original papers by Hoogerbrugge and Koelman (7) and Español and Warren (8). 3. Generation of Initial Structure Using gel 3.1...1–19. 7. Koelman, J. M. V. A.; Hoogerbrugge, P. J. Europhys. Lett. 1993, 21, 363–368. 8. Español , P.; Warren, P. B. Europhys. Lett. 1995, 30, 191

  6. Raman-Controlled Quantum Dots for Quantum Computing

    DTIC Science & Technology

    2005-11-30

    Phys. Rev. Lett. 80, 2245 s1998d. 17 M . B . Plenio , S. F. Huelga, A. Beige, and P. L. Knight, Phys. Rev. A 59, 2468 s1999d. 18 X.-L. Feng, Z.- M . Zhang, X...Gupta et al., Phys. Rev. B 59, R10421 (1999). [19] J. Javanainen, Europhys. Lett. 17, 407 (1992); G. C. Hegerfeldt and M . B . Plenio , Phys. Rev. A 46...atoms are Ge,1 m eV and a,1 meV, which means that SGC will not be observed in such a system. B . Entanglement and SGC of atomic hyperfine states In

  7. Properties of branching exponential flights in bounded domains

    NASA Astrophysics Data System (ADS)

    Zoia, A.; Dumonteil, E.; Mazzolo, A.

    2012-11-01

    In a series of recent works, important results have been reported concerning the statistical properties of exponential flights evolving in bounded domains, a widely adopted model for finite-speed transport phenomena (Blanco S. and Fournier R., Europhys. Lett., 61 (2003) 168; Mazzolo A., Europhys. Lett., 68 (2004) 350; Bénichou O. et al., Europhys. Lett., 70 (2005) 42). Motivated by physical and biological systems where random spatial displacements are coupled with Galton-Watson birth-death mechanisms, such as neutron multiplication, diffusion of reproducing bacteria or spread of epidemics, in this letter we extend those results in two directions, via a Feynman-Kac formalism. First, we characterize the occupation statistics of exponential flights in the presence of absorption and branching, and give explicit moment formulas for the total length travelled by the walker and the number of performed collisions in a given domain. Then, we show that the survival and escape probability can be derived as well by resorting to a similar approach.

  8. Revisiting Deng et al.'s Multiparty Quantum Secret Sharing Protocol

    NASA Astrophysics Data System (ADS)

    Hwang, Tzonelih; Hwang, Cheng-Chieh; Yang, Chun-Wei; Li, Chuan-Ming

    2011-09-01

    The multiparty quantum secret sharing protocol [Deng et al. in Chin. Phys. Lett. 23: 1084-1087, 2006] is revisited in this study. It is found that the performance of Deng et al.'s protocol can be much improved by using the techniques of block-transmission and decoy single photons. As a result, the qubit efficiency is improved 2.4 times and only one classical communication, a public discussion, and two quantum communications between each agent and the secret holder are needed rather than n classical communications, n public discussions, and 3n/2 quantum communications required in the original scheme.

  9. Discussion of “Geomechanical modeling of the nucleation process of Australia's 1989 M5.6 Newcastle earthquake” by C.D. Klose [Earth Planet. Sci. Lett. 256 (2007) 547 553

    NASA Astrophysics Data System (ADS)

    Quinn, C. D.; Glen, R. A.; Diessel, C. F. K.

    2008-05-01

    On the basis of a numerical simulation, Klose [Earth Planet. Sci. Lett. 256: 547-553 (2007)] proposed that the MW = 5.2-5.6 earthquake that nucleated beneath Newcastle (New South Wales, Australia) at 10.30 AM December 28, 1989 (AEST), was the result of 200yr of coal mining in the region. We argue here that Klose's [Earth Planet. Sci. Lett. 256: 547-553 (2007)] ultimate conclusion is not supported by his own model or by available geological and seismic data. In particular, the 1989 Newcastle earthquake was not anomalous with respect to regional seismic activity.

  10. Diagnosing ALS

    MedlinePlus

    ... that a person diagnosed with ALS seek a second opinion from an ALS "expert" - someone who diagnoses and treats many ALS patients and has training in this medical specialty. The ALS Association maintains a list of recognized experts in the field of ALS. See ALS Association Certified Centers of ...

  11. Dust in tokamaks: An overview of the physical model of the dust in tokamaks code

    NASA Astrophysics Data System (ADS)

    Bacharis, Minas; Coppins, Michael; Allen, John E.

    2010-04-01

    The dynamical behavior of dust produced in tokamaks is an important issue for fusion. In this work, the current status of the dust in tokamaks (DTOKS) [J. D. Martin et al., Europhys Lett. 83, 65001 (2008)] dust transport code will be presented. A detailed description of the various elements of its underlying physical model will be given together with representative simulation results for the mega amp spherical tokamak (MAST) [A. Sykes et al., Nucl. Fusion 41, 1423 (2001)]. Furthermore, a brief description of the various components of the dust transport (DUSTT) [R. D. Smirnov et al., Plasma Phys. Controlled Fusion 49, 347 (2007)] code will also be presented in comparison with DTOKS.

  12. Corrigendum to "Widespread occurrence of (per)chlorate in the Solar System" [Earth Planet. Sci. Lett. 430 (2015) 470-476

    NASA Astrophysics Data System (ADS)

    Jackson, W. Andrew; Davila, Alfonso F.; Sears, Derek; Coates, John D.; McKay, Christopher P.; Brundrett, Maeghan; Estrada, Nubia; Böhlke, J. K.

    2016-02-01

    The authors regret that two sets of data (Atacama (Rao et al., 2010) and Mars Meteorite Range (Kounaves et al., 2014)) in Fig. 2 of our article were plotted in the wrong units. The correction does not change the relationship between ClO3- and ClO4- ; it only shifts the magnitude of the concentrations. The conclusions of the article are not affected. The corrected Fig. 2 appears below.

  13. Comment on: “Effects of including the counterrotating term and virtual photons on the eigenfunctions and eigenvalues of a scalar photon collective emission theory” [Phys. Lett. A 372 (2008) 2514

    NASA Astrophysics Data System (ADS)

    Svidzinsky, Anatoly; Chang, Jun-Tao

    2008-08-01

    In a recent Letter [R. Friedberg, J.T. Manassah, Phys. Lett. A 372 (2008) 2514] Friedberg and Manassah argue that effect of virtual photons has serious consequences for large atomic samples. Here we show that such effect is negligible for evolution of a uniformly excited atomic state prepared by absorption of a single photon.

  14. ALS Association

    MedlinePlus

    ... toward a world without ALS! Walk to Defeat ALS® Walk to Defeat ALS® draws people of all ... We need your help. I Will Advocate National ALS Registry The National ALS Registry is a congressionally ...

  15. The Amigó paradigm of forbidden/missing patterns: a detailed analysis

    NASA Astrophysics Data System (ADS)

    Rosso, O. A.; Carpi, L. C.; Saco, P. M.; Ravetti, M. G.; Larrondo, H. A.; Plastino, A.

    2012-12-01

    We deal here with the issue of determinism versus randomness in time series (TS), with the goal of identifying their relative importance in a given TS. To this end we extend (i) the use of ordinal patterns based probability distribution functions associated to a TS [C. Bandt and B. Pompe, Phys. Rev. Lett. 88, 174102 (2002)] and (ii) the so-called Amigó paradigm of forbidden/missing patterns [J.M. Amigó et al., Europhys. Lett. 79, 50001 (2007)], to analyze deterministic finite TS contaminated with strong additive noises of different correlation-degree. Useful information on the deterministic component of the original time series is obtained with the help of the so-called causal entropy-complexity plane [O.A. Rosso et al., Phys. Rev. Lett. 99, 154102 (2007)].

  16. Corrigendum to "Deep water provenance and dynamics of the (de)glacial Atlantic meridional overturning circulation" [Earth Planet. Sci. Lett. 445 (2016) 68-78

    NASA Astrophysics Data System (ADS)

    Lippold, Jörg; Gutjahr, Marcus; Blaser, Patrick; Christner, Emanuel; de Carvalho Ferreira, Maria Luiza; Mulitza, Stefan; Christl, Marcus; Wombacher, Frank; Böhm, Evelyn; Antz, Benny; Cartapanis, Olivier; Vogel, Hendrik; Jaccard, Samuel L.

    2017-01-01

    We have reconstructed past modes of the Atlantic Meridional Overturning Circulation (AMOC) by combining two sedimentary proxies, Nd isotopes (εNd) and the 231Pa/230Th ratio over the last deglaciation. Combined down-core 231Pa/230Th and εNd records from six Atlantic Ocean sediment archives are presented (Lippold et al., 2016).

  17. A GaAs-AlGaAs Based Thyristor

    DTIC Science & Technology

    1989-06-01

    Levinshtein and V . E . Chelnokov , "Subnanosecond tum-on of gallium arsenide thyristors," Sov. Tech. Phys. Lett., vol. 12, pp. 383-384, 1986; and...Angeles, California 90024 Abstract: A study of bipolar junction thyristors based on GaAs and AlGaAs materials for pulsed power switching applications is...related III- V heterostructures can be made to exhibit subnanosecond current rise-times under pulse power conditions, and thus should be considered

  18. Further Precipitation Reactions Associated with Beta’ (Al3Zr) Particles in Al-Li-Cu-Mg-Zr Alloys

    DTIC Science & Technology

    1988-12-01

    Gregson 8’ precipitation in Al-Li-Mg-Cu-Zr alloys. H.M. Flower J. Mater. Sci. Lett., 3, 829 (1984) 5 P.L. Makin On the ageing of an aluminium-lithium...Technol., 2, 349 (1986) 8 H.M. Flower The effect of composition and heat treatment upon the et al microstructure/property relationships in Al-Li-Cu-Mg...1119 REFERENCES concluded) No. Author Title, etc 10 P.J. Gregon Microstructural control of toughness in aluminium- H.M. Flower lithium alloys. Acta

  19. ALS - resources

    MedlinePlus

    Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association -- www.mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) ...

  20. A Trio of Brownian Donkeys

    NASA Astrophysics Data System (ADS)

    van den Broeck, C.; Cleuren, B.; Kawai, R.; Kambon, M.

    A previously introduced model (B. Cleuren and C. Van den Broeck, Europhys. Lett. 54, 1 (2001)) is studied numerically. Pure negative mobility is found for the minimum number of three interacting walkers.

  1. Laplacian Growth of Parallel Needles: Their Mullins-Sekerka Instability

    DTIC Science & Technology

    2000-01-01

    conformal mapping allows to obtain analytical results as shown by Derrida and Hakim 6 for radial needles. An important question in such systems is the...and Bensimon1 °, Sz6p and Lugosi11 , Peterson and Furry 12 , Kurtze13 , and Derrida and Hakim6 . For the dynamics, we will follow here Derrida et al...Kassner, P. Meakin, and F. Family, Europhys. Lett. 27, 527 (1993). 5. J. Krug, Adv. Phys. 46, 158 (1997). 6. B. Derrida , and V. Hakim, Phys. Rev. A

  2. Modified Taylor-Couette Flow in Multiply-Waisted Hourglass Geometries Simulations based upon Reaction-Diffusion Models

    NASA Astrophysics Data System (ADS)

    Olsen, Thomas; Hou, Yu; Kowalski, Adam; Wiener, Richard

    2006-05-01

    The Reaction-Diffusion model predicted a period doubling cascade to chaos in a situation analagous Taylor- Couette flow with hourglass geometry. This cascade to chaos was discovered in the actual fluid flow experiments. We model Taylor-Couette flow in a cylindrical geometry with multiple waists of super-critical flow connected by regions of barely super-critical flow by corresponding Reaction-Diffusion models. We compare our results to the findings of an ongoing experimental program. H. Riecke and H.-G. Paap, Europhys. Lett. 14, 1235 (1991). Richard J. Wiener et al, Phys. Rev. E 55, 5489 (1997).

  3. Development of simultaneous measurement system of birefringence, optical rotational power, and transmission spectra for chiral liquid crystal phases

    NASA Astrophysics Data System (ADS)

    Feng, Zhengyu; Ishikawa, Ken

    2016-05-01

    A novel experimental setup used to measure the important optical properties of liquid crystal materials is proposed. The setup allows us to measure electric-field-induced birefringence, optical rotational power, and transmission spectra consecutively. This system can be widely applied to characterize liquid crystal materials including blue phases, ferroelectric liquid crystals, and other chiral phases. We adopted this system to study the phase transition behavior of a V-shape switching ferroelectric liquid crystal mixture and made an important correction of experimental results previously reported by Sandhya et al. [ Europhys. Lett. 90, 56005 (2010)]. This finding proves the advantage of this system compared with the measurement method using individual systems.

  4. Perfect entropy functions of the Lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Karlin, I. V.; Ferrante, A.; Öttinger, H. C.

    1999-07-01

    In this letter, we derive entropy functions whose local equilibria are suitable to recover the Navier-Stokes equations in the framework of the Lattice Boltzmann method. For the two-dimensional nine-velocity lattice we demonstrate that such an entropy function is unique, and that the expansion of the corresponding local equilibrium is the well-known local equilibrium of Y. H. Qian et al. (Europhys. Lett., 17 (1992) 479). Based on the knowledge of entropy functions, we introduce a new version of the Lattice Boltzmann method with an H-theorem built in.

  5. Orientation relationship of eutectoid FeAl and FeAl2

    PubMed Central

    Scherf, A.; Kauffmann, A.; Kauffmann-Weiss, S.; Scherer, T.; Li, X.; Stein, F.; Heilmaier, M.

    2016-01-01

    Fe–Al alloys in the aluminium range of 55–65 at.% exhibit a lamellar microstructure of B2-ordered FeAl and triclinic FeAl2, which is caused by a eutectoid decomposition of the high-temperature Fe5Al8 phase, the so-called ∊ phase. The orientation relationship of FeAl and FeAl2 has previously been studied by Bastin et al. [J. Cryst. Growth (1978 ▸), 43, 745] and Hirata et al. [Philos. Mag. Lett. (2008 ▸), 88, 491]. Since both results are based on different crystallographic data regarding FeAl2, the data are re-evaluated with respect to a recent re-determination of the FeAl2 phase provided by Chumak et al. [Acta Cryst. (2010 ▸), C66, i87]. It is found that both orientation relationships match subsequent to a rotation operation of 180° about a 〈112〉 crystallographic axis of FeAl or by applying the inversion symmetry of the FeAl2 crystal structure as suggested by the Chumak data set. Experimental evidence for the validity of the previously determined orientation relationships was found in as-cast fully lamellar material (random texture) as well as directionally solidified material (∼〈110〉FeAl || solidification direction) by means of orientation imaging microscopy and global texture measurements. In addition, a preferential interface between FeAl and FeAl2 was identified by means of trace analyses using cross sectioning with a focused ion beam. On the basis of these habit planes the orientation relationship between the two phases can be described by (01)FeAl || (114) and [111]FeAl || [10]. There is no evidence for twinning within FeAl lamellae or alternating orientations of FeAl lamellae. Based on the determined orientation and interface data, an atomistic model of the structure relationship of Fe5Al8, FeAl and FeAl2 in the vicinity of the eutectoid decomposition is derived. This model is analysed with respect to the strain which has to be accommodated at the interface of FeAl and FeAl2. PMID:27047304

  6. Self-Aligned ALD AlOx T-gate Insulator for Gate Leakage Current Suppression in SiNx-Passivated AlGaN/GaN HEMTs

    DTIC Science & Technology

    2010-01-01

    blanket-deposited between the source and drain, as has been demonstrated by Ye et al. [21]. Similiarly, Saadat and co-workers have used ALD-deposited HfOx...been reported previously by Saadat et al. [22] and noted to be indicative of slow trapping centers in the oxide and at the oxide/semiconductor...gate dielectric. Appl Phys Lett 2005;86:063501–3. [22] Saadat OI, Chung JW, Piner EL, Palacios T. Gate-first AlGaN/GaN HEMT technology for high-frequency

  7. Neutron scattering study of the freezing of water near a cupric oxide surface

    NASA Astrophysics Data System (ADS)

    Torres, J.; Buck, Z. N.; Zhang, F. Z.; Chen, T.; Winholtz, R. A.; Kaiser, H.; Ma, H. B.; Taub, H.; Tyagi, M.

    Oscillating heat pipes (OHP) offer promising two-phase heat transfer for a variety of applications, including cooling of electronic devices.2 Recently, it has been shown that a hydrophilic CuO coating on either the evaporator or condenser sections of a flat-plate OHP can significantly enhance its thermal performance.3 This finding has motivated us to assess the strength of the CuO/H2O interaction by investigating the freezing behavior of H2O in proximity to a CuO surface. Using the High-Flux Backscattering Spectrometer at NIST, we have measured the intensity of neutrons scattered elastically from a well-hydrated sample of CuO-coated Cu foils that mimic the oxide surfaces in a flat-plate OHP. We observe abrupt freezing of bulk-like H2O above the CuO surface at 270 K followed by continuous freezing of the interfacial H2O down to 265 K. This freezing behavior is qualitatively similar to that found for water near a zwitterionic single-supported bilayer lipid membrane.3 Further studies are planned to compare the diffusion coefficients of the interfacial water for the coated and uncoated OHPs.22F.Z. Zhang et al., submitted to J. Heat Transfer. 3M. Bai et al., Europhys. Lett. 98, 48006 (2012); Miskowiec et al., Europhys. Lett. 107, 28008 (2014). Supported by NSF Grant Nos. DMR-0944772 and DGE-1069091.

  8. Spin orbit torques and chiral spin textures in ultrathin magnetic films (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Beach, Geoffrey S.

    2015-09-01

    Spin orbit coupling at interfaces can give rise to chiral magnetic textures such as homochiral domain walls and skyrmions, as well as current-induced torques that can effectively manipulate them [1-3]. This talk will describe interface-driven spin-orbit torques and Dzyaloshinskii-Moriya interactions (DMIs) in ultrathin metallic ferromagnets adjacent to nonmagnetic heavy metals. We show that the DMI depends strongly on the heavy metal, differing by a factor of ~20 between Pt and Ta [4], and describe the influence of strong DMI on domain wall dynamics and spin Hall effect switching [5]. We present high-resolution magnetic force microscopy imaging of static magnetic textures that directly reveal the role of DMI and allow its strength to be quantified. Finally, we will describe how SOTs can be enhanced through interface engineering [6] and tuned by a gate voltage [7] by directly controlling the interfacial oxygen coordination at a ferromagnet/oxide interface [8]. [1] A. Thiaville, et al., Europhys. Lett. 100, 57002 (2012). [2] S. Emori, et al., Nature Mater. 12, 611 (2013). [3] J. Sampaio, V. Cros, S. Rohart, A. Thiaville, and A. Fert, Nature Nano. 8, 839 (2013). [4] S. Emori, et al., Phys. Rev. B 90, 184427 (2014). [5] N. Perez, et al., Appl. Phys. Lett. 104, 092403 (2014). [6] S. Woo, et al., Appl. Phys. Lett. 105, 212404 (2014). [7] S. Emori, et al., Appl. Phys. Lett. 105, 222401 (2014). [8] U. Bauer, et al., Nature Mater. 14, 174 (2015).

  9. AL Amyloidosis

    PubMed Central

    2012-01-01

    Definition of the disease AL amyloidosis results from extra-cellular deposition of fibril-forming monoclonal immunoglobulin (Ig) light chains (LC) (most commonly of lambda isotype) usually secreted by a small plasma cell clone. Most patients have evidence of isolated monoclonal gammopathy or smoldering myeloma, and the occurrence of AL amyloidosis in patients with symptomatic multiple myeloma or other B-cell lymphoproliferative disorders is unusual. The key event in the development of AL amyloidosis is the change in the secondary or tertiary structure of an abnormal monoclonal LC, which results in instable conformation. This conformational change is responsible for abnormal folding of the LC, rich in β leaves, which assemble into monomers that stack together to form amyloid fibrils. Epidemiology AL amyloidosis is the most common type of systemic amyloidois in developed countries with an estimated incidence of 9 cases/million inhabitant/year. The average age of diagnosed patients is 65 years and less than 10% of patients are under 50. Clinical description The clinical presentation is protean, because of the wide number of tissues or organs that may be affected. The most common presenting symptoms are asthenia and dyspnoea, which are poorly specific and may account for delayed diagnosis. Renal manifestations are the most frequent, affecting two thirds of patients at presentation. They are characterized by heavy proteinuria, with nephrotic syndrome and impaired renal function in half of the patients. Heart involvement, which is present at diagnosis in more than 50% of patients, leading to restrictive cardiopathy, is the most serious complication and engages prognosis. Diagnostic methods The diagnosis relies on pathological examination of an involved site showing Congo red-positive amyloid deposits, with typical apple-green birefringence under polarized light, that stain positive with an anti-LC antibody by immunohistochemistry and/or immunofluorescence. Due to the

  10. Pronounced minimum of the thermodynamic Casimir forces of O(n) symmetric film systems: analytic theory.

    PubMed

    Dohm, Volker

    2014-09-01

    Thermodynamic Casimir forces of film systems in the O(n) universality classes with Dirichlet boundary conditions are studied below bulk criticality. Substantial progress is achieved in resolving the long-standing problem of describing analytically the pronounced minimum of the scaling function observed experimentally in ^{4}He films (n=2) by Garcia and Chan [Phys. Rev. Lett. 83, 1187 (1999)] and in Monte Carlo simulations for the three-dimensional Ising model (n=1) by O. Vasilyev et al. [Europhys. Lett. 80, 60009 (2007)]. Our finite-size renormalization-group approach describes the film systems as the limit of finite-slab systems with vanishing aspect ratio. This yields excellent agreement with the depth and the position of the minimum for n=1 and semiquantitative agreement with the minimum for n=2. Our theory also predicts a pronounced minimum for the n=3 Heisenberg universality class.

  11. Polarity Control and Growth of Lateral Polarity Structures in AlN

    DTIC Science & Technology

    2013-05-10

    the broadening are negligible and can be simply explained with the difference in the strain level.18 Low temperature (5 K ) photoluminescence spectra...temperature Raman spectra of the Al-polar and N-polar domains recorded in z(xx)z geometry. FIG. 5. Low temperature (5 K ) photoluminescence spectra of the Al...Sitar, Appl. Phys. Lett. 92(4), 041911–041913 (2008). 3S. Rajan, A. Chini, M. H. Wong, J. S. Speck, and U. K . Mishra, J. Appl. Phys. 102(4), 044501

  12. Relaxation of compressively strained AlGaN by inclined threading dislocations.

    SciTech Connect

    Follstaedt, David Martin; Lee, Stephen Roger; Crawford, Mary Hagerott; Provencio, Paula Polyak; Allerman, Andrew Alan; Floro, Jerrold Anthony

    2005-06-01

    Transmission electron microscopy and x-ray diffraction were used to assess the microstructure and strain of Al{sub x}Ga{sub 1?x}N(x = 0.61-0.64) layers grown on AlN. The compressively-strained AlGaN is partially relaxed by inclined threading dislocations, similar to observations on Si-doped AlGaN by P. Cantu, F. Wu, P. Waltereit, S. Keller, A. E. Romanov, U. K. Mishra, S. P. DenBaars, and J. S. Speck [Appl. Phys. Lett. 83, 674 (2003) ]; however, in our material, the dislocations bend before the introduction of any Si. The bending may be initiated by the greater lattice mismatch or the lower dislocation density of our material, but the presence of Si is not necessarily required. The relaxation by inclined dislocations is quantitatively accounted for with the model of A. E. Romanov and J. S. Speck [Appl. Phys. Lett. 83, 2569 (2003)], and we demonstrate the predicted linear dependence of relaxation on layer thickness. Notably, such relaxation was not found in tensile strained AlGaN grown on GaN [J. A. Floro, D. M. Follstaedt, P. Provencio, S. J. Hearne, and S. R. Lee, J. Appl. Phys. 96, 7087 (2004)], even though the same mechanism appears applicable.

  13. Experimental Progress on the NIST ^27Al^+ Optical Clock

    NASA Astrophysics Data System (ADS)

    Chou, Chin-Wen; Hume, David B.; Koelemeij, Jeroen C. J.; Rosenband, Till; Bergquist, James C.; Wineland, Dave J.

    2009-05-01

    A recent measurement of the frequency ratio between single-ion optical clocks based on ^27Al^+ and ^199Hg^+ at NIST showed a combined statistical and systematic uncertainty of 5.2 x 10-17[1]. Here we report progress on improving both the accuracy and stability of the ^27Al^+ optical clock. We have developed a new trap and laser systems that enable the use of ^25Mg^+ for sympathetic cooling and clock-state detection of ^27Al^+. These developments should reduce time-dilation shifts caused by harmonic motion of the ions and thus lower the dominant systematic uncertainty below 10-17. In the new clock apparatus we have demonstrated spectroscopy of the ^27Al^+ ^1S0 to ^3P0 transition with a quality factor of Q = 3.5 x 10^14 and simultaneously a contrast approaching unity. In addition, we have developed techniques for the sympathetic laser cooling and quantum logic spectroscopy of multiple aluminum ions with the goal of further improving measurement stability [2]. *supported by ONR and NIST [1] T. Rosenband et al., Science 319, 1808 (2008) [2] D. B. Hume et al., Phys. Rev. Lett. 99, 120502 (2007)

  14. Comment on "Hydrothermal preparation of analogous matrix minerals of CM carbonaceous chondrites from metal alloy particles" by Y. Peng and Y. Jing [Earth Planet. Sci. Lett. 408 (2014) 252-262

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Vacher, Lionel G.; Marrocchi, Yves

    2015-10-01

    Peng and Jing (2014) recently reported the results of hydrothermal experiments designed to produce synthetic tochilinite/cronstedtite assemblages analogous to those found in the matrix of CM chondrites (Tomeoka and Buseck, 1982, 1983a, 1983b, 1985; Mackinnon and Zolensky, 1984; Zolensky and Mackinnon, 1986; Rubin et al., 2007; Bourot-Denise et al., 2010; Hewins et al., 2014; Marrocchi et al., 2014). The assemblage was obtained from an alloyed metal particle mixture of Fe, Mg, Al, Si, Cr and Ni under basic, reducing and S2--rich conditions. The hydrothermal syntheses were conducted in Teflon-lined stainless-steel autoclaves at temperature of 106-160 °C for short-duration runs and at 153 °C for long-duration runs. The phases in the assemblage were characterized by XRD and TEM, but only the analytical results of long-duration runs were reported in the article and in the Appendix as supplementary material. The phases identified were: cronstedtite and tochilinite (both present in all run products), tochilinite-cronstedtite intergrowths, polyhedral serpentine, a chrysotile-like phase, nanotube-like structures, and lizardite-like and brucite-like phases. Based on their experimental results, the authors put forward a hypothesis to explain the formation of matrix minerals in CM chondrites proposing that the precursors may be nanometer- to micrometer-sized particles of metal alloys that were altered at low temperatures by interaction with S-rich water under reducing and dynamic pressurized conditions.

  15. Nanostructured Silicon for Electronic and Electromechanic Devices

    NASA Astrophysics Data System (ADS)

    Kotthaus, Jorg P.

    2001-03-01

    Fabrication technologies with nanometer resolution enable us now to realize silicon devices in which the electronic and electromechanical functions are governed by artificial geometric confinement and may sensitively depend on the environment. One example are single electron tranistors fabricated on silicon-on-insulator substrates in which the quantum confinement of electrons down to 10 nm yields strongly aperiodic Coulomb blockade oscillations of the conductance visible up to temperatures well above 100 K /1/. Another are suspended nanoelectromechanical resonators exhibiting highly non-linear resonances at radio frequencies /2/. These can be employed for mechanical radio frequency mixing as well as for sensitively sensing their local environment. Alternatively, nanomechanical levers can serve as electrical switching devices with very high resonance frequencies/3/. The perspectives of using such silicon-based nanodevices for local manipulation and sensing applications and high frequency signal processing will be discussed. /1/ A. Tilke et al., Appl. Phys. Lett. 75, 3704 (1999) and Appl. Phys. A71, 357 (2000) /2/ L. Pescini et al., Nanotechnology 10, 418 (1999), H. Krömmer et al., Europhys. Lett. 50, 101 (2000) /3/ A. Erbe et al., Appl. Phys. Lett. 73, 3751 (1998), A. Erbe et al., Physica B280, 553 (2000)

  16. Relaxation of compressively-strained AlGaN by inclined threading dislocations

    NASA Astrophysics Data System (ADS)

    Follstaedt, D. M.; Lee, S. R.; Provencio, P. P.; Allerman, A. A.; Floro, J. A.; Crawford, M. H.

    2005-09-01

    Transmission electron microscopy and x-ray diffraction were used to assess the microstructure and strain of AlxGa1-xN(x=0.61-0.64) layers grown on AlN. The compressively-strained AlGaN is partially relaxed by inclined threading dislocations, similar to observations on Si-doped AlGaN by P. Cantu, F. Wu, P. Waltereit, S. Keller, A. E. Romanov, U. K. Mishra, S. P. DenBaars, and J. S. Speck [Appl. Phys. Lett. 83, 674 (2003)]; however, in our material, the dislocations bend before the introduction of any Si. The bending may be initiated by the greater lattice mismatch or the lower dislocation density of our material, but the presence of Si is not necessarily required. The relaxation by inclined dislocations is quantitatively accounted for with the model of A. E. Romanov and J. S. Speck [Appl. Phys. Lett. 83, 2569 (2003)], and we demonstrate the predicted linear dependence of relaxation on layer thickness. Notably, such relaxation was not found in tensile strained AlGaN grown on GaN [J. A. Floro, D. M. Follstaedt, P. Provencio, S. J. Hearne, and S. R. Lee, J. Appl. Phys. 96, 7087 (2004)], even though the same mechanism appears applicable.

  17. Al-doping influence on crystal growth of Ni-Al alloy: Experimental testing of a theoretical model

    NASA Astrophysics Data System (ADS)

    Rong, Xi-Ming; Chen, Jun; Li, Jing-Tian; Zhuang, Jun; Ning, Xi-Jing

    2015-12-01

    Recently, a condensing potential model was developed to evaluate the crystallization ability of bulk materials [Ye X X, Ming C, Hu Y C and Ning X J 2009 J. Chem. Phys. 130 164711 and Peng K, Ming C, Ye X X, Zhang W X, Zhuang J and Ning X J 2011 Chem. Phys. Lett. 501 330], showing that the best temperature for single crystal growth is about 0.6Tm, where Tm is the melting temperature, and for Ni-Al alloy, more than 6 wt% of Al-doping will badly reduce the crystallization ability. In order to verify these predictions, we fabricated Ni-Al films with different concentrations of Al on Si substrates at room temperature by pulsed laser deposition, and post-annealed the films at 833, 933, 1033 (˜ 0.6Tm), 1133, and 1233 K in vacuum furnace, respectively. The x-ray diffraction spectra show that annealing at 0.6Tm is indeed best for larger crystal grain formation, and the film crystallization ability remarkably declines with more than 6-wt% Al doping. Project supported by the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20130071110018) and the National Natural Science Foundation of China (Grant No. 11274073).

  18. What Is ALS?

    MedlinePlus

    ... Javits, actor David Niven, “Sesame Street” creator Jon Stone, boxing champion Ezzard Charles, NBA Hall of Fame ... Help for People with ALS and Caregivers Read stories from families living with ALS Forms of ALS ...

  19. Relativistic general-order coupled-cluster method for high-precision calculations: Application to the Al+ atomic clock

    NASA Astrophysics Data System (ADS)

    Kállay, Mihály; Nataraj, H. S.; Sahoo, B. K.; Das, B. P.; Visscher, Lucas

    2011-03-01

    We report the implementation of a general-order relativistic coupled-cluster method for performing high-precision calculations of atomic and molecular properties. As a first application, the black-body radiation shift of the Al+ clock has been estimated precisely. The computed shift relative to the frequency of the 3s21S0e→3s3p3P0o clock transition given by (-3.66±0.60)×10-18 calls for an improvement over the recent measurement with a reported result of (-9±3)×10-18 [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.104.070802 104, 070802 (2010)].

  20. Bose Fluids Above Tc: Incompressible Vortex Fluids and ``Supersolidity''

    NASA Astrophysics Data System (ADS)

    Anderson, P. W.

    2008-05-01

    This Letter emphasizes that nonlinear rotational or diamagnetic susceptibility is characteristic of Bose fluids above their superfluid TC’s. For sufficiently slow rotation or, for superconductors, weak B fields, this amounts to an incompressible response to vorticity. The cause is that there are terms missing in the conventionally accepted model Hamiltonian for quantized vortices in the Bose fluid. The resulting susceptibility can account for recent observations of Chan et al. [Nature (London)NATUAS0028-0836 427, 225 (2004); 10.1038/nature02220ScienceSCIEAS0036-8075 305, 1941 (2004)10.1126/science.1101501] on solid He and Ong et al. [Europhys. Lett.EULEEJ0295-5075 72, 451 (2005)10.1209/epl/i2005-10254-4] on cuprate superconductors.

  1. Enhanced NMR Relaxation of Tomonaga-Luttinger Liquids and the Magnitude of the Carbon Hyperfine Coupling in Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kiss, A.; Pályi, A.; Ihara, Y.; Wzietek, P.; Simon, P.; Alloul, H.; Zólyomi, V.; Koltai, J.; Kürti, J.; Dóra, B.; Simon, F.

    2011-10-01

    Recent transport measurements [Churchill et al. Nature Phys.NPAHAX1745-2473 5, 321 (2009)10.1038/nphys1247] found a surprisingly large, 2-3 orders of magnitude larger than usual C13 hyperfine coupling (HFC) in C13 enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17 004 (2010)EULEEJ0295-507510.1209/0295-5075/90/17004]. Though we find that 1/T1 is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters.

  2. A pressure tensor description for the time-resonant Weibel instability

    NASA Astrophysics Data System (ADS)

    Sarrat, M.; Del Sarto, D.; Ghizzo, A.

    2017-02-01

    We discuss a fluid model with inclusion of the complete pressure tensor dynamics for the description of Weibel-type instabilities in a counterstreaming beam configuration. Differently from the case recently studied in Sarrat et al. (Europhys. Lett., vol. 115, 2016, 45001), where perturbations perpendicular to the beams were considered, here we focus only on modes propagating along the beams. Such a configuration is responsible for the growth of two kinds of instabilities, the two-stream instability and the Weibel instability, which in this geometry becomes `time resonant', i.e. propagating. This fluid description agrees with the kinetic one and makes it possible e.g. to identify the transition between non-propagating and propagating Weibel modes, already evidenced by Lazar et al. (J. Plasma Phys., vol. 76 (1), 2010, p. 49) as a `slope breaking' of the growth rate, in terms of a merger of two non-propagating Weibel modes.

  3. Abu al-Layth al-Libi

    DTIC Science & Technology

    2015-02-01

    Introduction In the tradition of post-9/11 senior Arab militant figures operating in Khurasan (the Afghanistan-Pakistan region), there is little doubt as to...the standing of Libyan jihadi commander Abu al-Layth al-Libi. If Usama bin Ladin and Ayman al-Zawahiri came to be the most prominent Arab -Afghan...Libi, a longtime leader of the Libyan Islamic Fighting Group (LIFG), who rapidly established himself as the champion of the Arab -Afghan milieu after

  4. Thermostat with a local heat-bath coupling for exact energy conservation in dissipative particle dynamics.

    PubMed

    Pastewka, Lars; Kauzlarić, David; Greiner, Andreas; Korvink, Jan G

    2006-03-01

    We present a Markov process which models particle hydrodynamics with conservation of the first three momenta. This is achieved by extending the [Peters, Europhys. Lett. 66, 311 (2004)] and [Lowe, Europhys. Lett. 47, 145 (1999)] method to incorporate energy conservation. The equivalence of the energy conserving Peters method and dissipative particle dynamics with energy conservation (DPDE) in the limit of a vanishing time step is shown. Simple numerical experiments clearly demonstrate the applicability of the methods. This overcomes current limitations of DPDE in the study of complex fluids in the (N,V,E) ensemble.

  5. Role of interference in the photosynthetic heat engine.

    PubMed

    Xu, Y Y; Liu, J

    2014-11-01

    The observation of quantum coherence in pigment-protein complexes has attracted considerable interest. One such endeavor entails applying a quantum heat engine to model the photosynthetic reaction center, but the definition of work used is inconsistent with that defined in quantum thermodynamics. Using the definition of work proposed in Weimer et al. [Europhys. Lett. 83, 30008 (2008)EULEEJ0295-507510.1209/0295-5075/83/30008], we investigated two proposals for enhancing the performance of the photosynthetic reaction center. In proposal A, which is similar to that in Dorfman et al. [Proc. Natl. Acad. Sci. USA 110, 2746 (2013)PNASA60027-842410.1073/pnas.1212666110], we found that the power and current-voltage characteristic of the heat engine can be increased by Fano interference but the efficiency cannot. In proposal B, which is similar to that in Creatore et al. [Phys. Rev. Lett. 111, 253601 (2013)PRLTAO0031-900710.1103/PhysRevLett.111.253601], we found that the mechanism of strengthening the performance of the heat engine is invalid; i.e., the dipole-dipole interaction between two electron donors could not increase the power, efficiency, or current-voltage characteristic.

  6. Role of interference in the photosynthetic heat engine

    NASA Astrophysics Data System (ADS)

    Xu, Y. Y.; Liu, J.

    2014-11-01

    The observation of quantum coherence in pigment-protein complexes has attracted considerable interest. One such endeavor entails applying a quantum heat engine to model the photosynthetic reaction center, but the definition of work used is inconsistent with that defined in quantum thermodynamics. Using the definition of work proposed in Weimer et al. [Europhys. Lett. 83, 30008 (2008), 10.1209/0295-5075/83/30008], we investigated two proposals for enhancing the performance of the photosynthetic reaction center. In proposal A, which is similar to that in Dorfman et al. [Proc. Natl. Acad. Sci. USA 110, 2746 (2013), 10.1073/pnas.1212666110], we found that the power and current-voltage characteristic of the heat engine can be increased by Fano interference but the efficiency cannot. In proposal B, which is similar to that in Creatore et al. [Phys. Rev. Lett. 111, 253601 (2013), 10.1103/PhysRevLett.111.253601], we found that the mechanism of strengthening the performance of the heat engine is invalid; i.e., the dipole-dipole interaction between two electron donors could not increase the power, efficiency, or current-voltage characteristic.

  7. Photoelectron Angular Distribution Asymmetry Parameters for Photodetachment of Li^- and Al^-.

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Nan; Starace, Anthony F.

    1997-04-01

    Calculation of photoelectron angular distribution asymmetry parameters for photodetachment precesses is a more stringent test for theory than calculation of partial or total cross sections. Since asymmetry parameters involve ratios of transition matrix elements of different channels, they are particularly sensitive to the resonance behavior of transition matrix elements. We present the asymmetry parameters for photodetachment of Li^- (2s^2 ^1S) and Al^- (3s^23p^2 ^3P) using the eigenchannel R-matrix method(U.Fano and C.M. Lee, Phys. Rev. Lett. 31), 1573 (1973)^,(C.H. Greene, in Fundamental Processes of Atomic Dynamics,) edited by J.S. Briggs, H. Kleinpoppen, and H.O. Lutz (Plenum, New York, 1988), pp.105-127.. Our results are in good agreement with the available Al^- photodetachment measurements(A.M. Covington et al.), U of Nevada-Reno, private communication..

  8. /Cu-Al System

    NASA Astrophysics Data System (ADS)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

  9. Initial Symptoms of ALS

    MedlinePlus

    ... Chapters Certified Centers and Clinics Support Groups About ALS About Us Our Research In Your Community Advocate ... Diagnosis En español Symptoms The initial symptoms of ALS can be quite varied in different people. One ...

  10. Lou Gehrig's Disease (ALS)

    MedlinePlus

    ... 1930s. People in England and Australia call ALS motor neurone disease (MND). The French refer to it ... about ALS in 1869. Lou Gehrig's disease damages motor neurons in the brain and spinal cord. Motor ...

  11. Iron Partitioning in the Lower Mantle: New Experimental Data from Al-Enriched Olivine

    NASA Astrophysics Data System (ADS)

    Piet, H.; Nabiei, F.; Gillet, P.; Badro, J.

    2014-12-01

    The partitioning of iron between the major phases of the lower mantle has an important impact on their physical and chemical properties. A series of experimental studies of Fe-Mg exchange between bridgemanite (magnesium silicate perovskite) and ferropericlase have shown that stark differences in partitioning are observed if olivine [1, 2] or a pyrolitic [3, 4] starting composition are used. The discrepancy has been attributed to the presence of alumina, to that of ferric iron, to multiphase equilibria and even to the activity of FeO in the system. In order to mitigate the discrepancy, we synthesized a sample with San Carlos olivine composition that was doped in alumina. We then used this as starting material for experiments in the laser-heated diamond anvil cell at lower mantle (P,T) conditions along the geotherm. Samples were pressurized, heated, transformed to bridgemanite and ferropericlase, equilibrated, quenched, and decompressed. Thin sections were recovered from the hotspot using a focused ion beam microscope and the composition of the two phases was analyzed using analytical transmission electron microscopy. Iron partitioning in Al-rich olivine will be discussed through a detailed comparison with the Al-rich pyrolitic trend and the Al-free olivine trend. References [1] A-L. Auzende et al., Earth Planet. Sci. Lett., 2008. [2] R. Sinmyo et al., J. Geophys. Res., 2008.[3] R. Irifune et al., Science, 2010. [4] R. Sinmyo et al., Phys. Chem. Minerals, 2013.

  12. The Aharonov-Bohm effect and Tonomura et al. experiments: Rigorous results

    SciTech Connect

    Ballesteros, Miguel; Weder, Ricardo

    2009-12-15

    The Aharonov-Bohm effect is a fundamental issue in physics. It describes the physically important electromagnetic quantities in quantum mechanics. Its experimental verification constitutes a test of the theory of quantum mechanics itself. The remarkable experiments of Tonomura et al. ['Observation of Aharonov-Bohm effect by electron holography', Phys. Rev. Lett 48, 1443 (1982) and 'Evidence for Aharonov-Bohm effect with magnetic field completely shielded from electron wave', Phys. Rev. Lett 56, 792 (1986)] are widely considered as the only experimental evidence of the physical existence of the Aharonov-Bohm effect. Here we give the first rigorous proof that the classical ansatz of Aharonov and Bohm of 1959 ['Significance of electromagnetic potentials in the quantum theory', Phys. Rev. 115, 485 (1959)], that was tested by Tonomura et al., is a good approximation to the exact solution to the Schroedinger equation. This also proves that the electron, that is, represented by the exact solution, is not accelerated, in agreement with the recent experiment of Caprez et al. in 2007 ['Macroscopic test of the Aharonov-Bohm effect', Phys. Rev. Lett. 99, 210401 (2007)], that shows that the results of the Tonomura et al. experiments can not be explained by the action of a force. Under the assumption that the incoming free electron is a Gaussian wave packet, we estimate the exact solution to the Schroedinger equation for all times. We provide a rigorous, quantitative error bound for the difference in norm between the exact solution and the Aharonov-Bohm Ansatz. Our bound is uniform in time. We also prove that on the Gaussian asymptotic state the scattering operator is given by a constant phase shift, up to a quantitative error bound that we provide. Our results show that for intermediate size electron wave packets, smaller than the ones used in the Tonomura et al. experiments, quantum mechanics predicts the results observed by Tonomura et al. with an error bound smaller than 10

  13. Cold Rydberg atoms in circular states

    NASA Astrophysics Data System (ADS)

    Anderson, David; Schwarzkopf, Andrew; Raithel, Georg

    2012-06-01

    Circular-state Rydberg atoms are interesting in that they exhibit a unique combination of extraordinary properties; long lifetimes (˜n^5), large magnetic moments (l=|m|=n-1) and no first order Stark shift. Circular states have found applications in cavity quantum electrodynamics and precision measurements [1,2], among other studies. In this work we present the production of circular states in an atom trapping apparatus using an adiabatic state-switching method (the crossed-field method [3]). To date, we have observed lifetimes of adiabatically prepared states of several milliseconds. Their relatively large ionization electric fields have been verified by time-of-flight signatures of ion trajectories. We intend to explore the magnetic trapping of circular state Rydberg atoms, as well as their production and interaction properties in ultra-cold and degenerate samples.[4pt] [1] P. Bertet et al., Phys. Rev. Lett., 88, 14 (2002)[0pt] [2] M. Brune et al., Phys. Rev. Lett., 72, 21 (1994)[0pt] [3] D. Delande and J.C. Gay, Europhys. Lett., 5, 303-308 (1988).

  14. Taylor-Couette Flow with Hourglass Geometry of Varying Lengths Simulated by Reaction-Diffusion

    NASA Astrophysics Data System (ADS)

    Zhao, Yunjie; Halmstad, Andrew; Olsen, Thomas; Wiener, Richard

    2008-11-01

    Previously, we have observed chaotic formation of Taylor-Vortex pairs in Modified Taylor- Couette Flow with Hourglass Geometry. In the experiment, the chaotic formation in a shorter system has been restricted to a narrow band about the waist of the hourglass. Such behavior has been modeled by The Reaction-Diffusion equation, which has been previously studied, by Riecke and Paap. Their calculation suggested that quadrupling length of the system would lead to spatial chaos in the vortex formation. We present a careful recreation of this result and consider an intermediate length. We demonstrate that doubling the length should be sufficient to observe spatially chaotic behavior. Richard J. Wiener et al, Phys. Rev. E 55, 5489 (1997). H. Riecke and H.-G. Paap, Europhys. Lett. 14, 1235 (1991).

  15. Transition to Spatio-Temporal Chaos with Increasing Length in the Reaction-Diffusion System

    NASA Astrophysics Data System (ADS)

    Trail, Collin; Tomlin, Brett; Olsen, Thomas; Wiener, Richard J.

    2003-11-01

    Calculations based up the Reaction-Diffusion model (H. Riecke and H.-G. Paap, Europhys. Lett. 14), 1235 (1991).have proven to be suggestive for a wide variety of pattern forming systems, including Taylor-Couette flow with hourglass geometry(Richard J. Wiener et al), Phys. Rev. E 55, 5489 (1997).. Seeking insight to guide experimental investigations, we extend these calculations. Previous calculations indicated that in smaller systems, only temporal chaos, located in a small region, would be observed, while in longer systems instabilities would form over a wide region. Our simulations explore this transition from purely temporal chaos to spatio-temporal chaos as the length of the system is increased.

  16. Reaction-Diffusion Model Simulations relevant to Modified Taylor-Couette Flow in Systems of Varying Length

    NASA Astrophysics Data System (ADS)

    Halmstad, Andrew; Olsen, Thomas; Wiener, Richard

    2006-11-01

    Previously, we have observed a period-doubling cascade to chaos in Modified Taylor-Couette Flow with Hourglass Geometry. Such behavior had been predicted by The Reaction-Diffusion model simulations. The chaotic formation of Taylor-Vortex pair formation was restricted to a very narrow band about the waist of the hourglass. It was suggested that with increasing lengths of systems, the chaotic region would expand. We present a battery of simulations to determine the variation of the size of the chaotic region with length, seeking the transition to spatio- temporal chaos. Richard J. Wiener et al, Phys. Rev. E 55, 5489 (1997). H. Riecke and H.-G. Paap, Europhys. Lett. 14, 1235 (1991).

  17. Simulations of the Reaction-Diffusion System demonstrating the Transition from Purely Temporal to Spatio-Temporal Chaos

    NASA Astrophysics Data System (ADS)

    Olsen, Thomas; Hou, Yu; Trail, Collin; Wiener, Richard

    2004-11-01

    The Reaction-Diffusion model (H. Riecke and H.-G. Paap, Europhys. Lett. 14), 1235 (1991).has been applied to a wide variety of pattern forming systems. It correctly predicted a period doubling cascade to chaos in Taylor-Couette flow with hourglass geometry(Richard J. Wiener et al), Phys. Rev. E 55, 5489 (1997).. We have conducted a series of such simulations, varying the length of the system. This has enabled us to study the transition from a purely temporal chaos of the formation of new pairs of Taylor Vortices at a single location, to a spatio-temporal chaos of formation across a range of locations. Application to anticipated experiments will be discussed.

  18. Yielding behavior of dense microgel glasses

    NASA Astrophysics Data System (ADS)

    Joshi, R. G.; Tata, B. V. R.; Karthickeyan, D.

    2013-02-01

    We report here the yielding behavior of dense suspensions of stimuli-responsive poly-N-isopropyl acrylamide (PNIPAM) microgel particles studied by performing oscillatory shear measurements. At a volume fraction of φ = 0.6 (labeled as sample S1) the suspension is characterized to be repulsive glass by dynamic light scattering technique and showed one step yielding. Quite interestingly higher volume fraction sample (S2) prepared by osmotically compressing sample S1, showed yielding occurring in two steps. Such one step yielding behavior turning into two step yielding was reported by Pham et al [Europhys. Lett., 75, 624 (2006)] in hard-sphere repulsive colloidal glass when transformed into an attractive glass by inducing depletion attraction. We confirm the repulsive interparticle interaction between PNIPAM microgel particles turning into attractive upon osmotic compression by static light scattering measurements.

  19. Linear response of hydrodynamically-coupled particles under a nonequilibrium reservoir

    NASA Astrophysics Data System (ADS)

    Yolcu, Cem; Baiesi, Marco

    2016-03-01

    A recent experiment driving colloids electromagnetically, by Bérut et al 2014 Europhys. Lett. 107 60004, is an ideal paradigm for illustrating a linear response theory for nonequilibrium overdamped systems including hydrodynamic interactions and, unusually, a reservoir itself out of equilibrium. Indeed, in this setup one finds a nonequilibrium environment in which the mobility and diffusivity of free particles are not simply proportional to each other. We derive both the response to a mechanical forcing and to temperature variations in terms of correlations between an observable and a path-weight action. The time-antisymmetric component of the latter turns out not to be simply proportional to the heat flowing into the environment. These results are visualized with simulations resembling conditions and protocols easily realizable in the experiment, thereby tracing a path for experimental verifications of the theory.

  20. Photon generation in ferromagnetic point contacts

    NASA Astrophysics Data System (ADS)

    Kadigrobov, A. M.; Shekhter, R. I.; Jonson, M.

    2012-12-01

    We show theoretically that a significant spin accumulation can occur in electric point contacts between two ferromagnetic electrodes with different magnetizations. Under appropriate conditions an inverse population of spin-split electronic levels results in stimulated emission of photons in the presence of a resonant electromagnetic field. The intensity of the emitted radiation can be several orders of magnitude higher than in typical semiconductor laser materials for two reasons. (1) The density of conduction electrons in a metal point contact is much larger than in semiconductors. (2) The strength of the coupling between the electron spins and the electromagnetic field that is responsible for the radiative spin-flip transitions is set by the magnetic exchange energy and can therefore be very large, as suggested by Kadigrobov et al. [Europhys. Lett. 67, 948 (2004)].

  1. Rectangular model of a ballistic spin interferometer in (001) InGaAs/InAlAs quantum wells

    NASA Astrophysics Data System (ADS)

    Koga, Takaaki; Faniel, S.; Mineshige, S.; Mastuura, T.; Sekine, Y.

    2010-01-01

    We report an unambiguous detection of the crytalline anisotropy of the spin-orbit interaction in (001) InAlAs/InGaAs/InAlAs quantum wells using nanofabricated rectangular loop arrays, where the sides of the constituent loops are aligned along either the [110] or [ 1 1 ¯ 0] crystallographic axis. The fabrication and measurements were performed on the epi-wafer samples whose spin properties were characterized previously [Koga et al. Phys. Rev. Lett 89 (2002) 046801]. We find that the experimentally observed spin interference patterns - the amplitude modulation of the Al'tshuler-Aronov-Spivak oscillations as a function of the gate voltage - are in good agreement with the results of the spin interferometer model extended for rectangular loops and including both the Rashba and Dresselhaus spin-orbit interactions.

  2. Stability and dynamics of droplets on patterned substrates: insights from experiments and lattice Boltzmann simulations.

    PubMed

    Varnik, F; Gross, M; Moradi, N; Zikos, G; Uhlmann, P; Müller-Buschbaum, P; Magerl, D; Raabe, D; Steinbach, I; Stamm, M

    2011-05-11

    The stability and dynamics of droplets on solid substrates are studied both theoretically and via experiments. Focusing on our recent achievements within the DFG-priority program 1164 (Nano- and Microfluidics), we first consider the case of (large) droplets on the so-called gradient substrates. Here the term gradient refers to both a change of wettability (chemical gradient) or topography (roughness gradient). While the motion of a droplet on a perfectly flat substrate upon the action of a chemical gradient appears to be a natural consequence of the considered situation, we show that the behavior of a droplet on a gradient of topography is less obvious. Nevertheless, if care is taken in the choice of the topographic patterns (in order to reduce hysteresis effects), a motion may be observed. Interestingly, in this case, simple scaling arguments adequately account for the dependence of the droplet velocity on the roughness gradient (Moradi et al 2010 Europhys. Lett. 89 26006). Another issue addressed in this paper is the behavior of droplets on hydrophobic substrates with a periodic arrangement of square shaped pillars. Here, it is possible to propose an analytically solvable model for the case where the droplet size becomes comparable to the roughness scale (Gross et al 2009 Europhys. Lett. 88 26002). Two important predictions of the model are highlighted here. (i) There exists a state with a finite penetration depth, distinct from the full wetting (Wenzel) and suspended (Cassie-Baxter, CB) states. (ii) Upon quasi-static evaporation, a droplet initially on the top of the pillars (CB state) undergoes a transition to this new state with a finite penetration depth but then (upon further evaporation) climbs up the pillars and goes back to the CB state again. These predictions are confirmed via independent numerical simulations. Moreover, we also address the fundamental issue of the internal droplet dynamics and the terminal center of mass velocity on a flat substrate.

  3. Stability and dynamics of droplets on patterned substrates: insights from experiments and lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Varnik, F.; Gross, M.; Moradi, N.; Zikos, G.; Uhlmann, P.; Müller-Buschbaum, P.; Magerl, D.; Raabe, D.; Steinbach, I.; Stamm, M.

    2011-05-01

    The stability and dynamics of droplets on solid substrates are studied both theoretically and via experiments. Focusing on our recent achievements within the DFG-priority program 1164 (Nano- and Microfluidics), we first consider the case of (large) droplets on the so-called gradient substrates. Here the term gradient refers to both a change of wettability (chemical gradient) or topography (roughness gradient). While the motion of a droplet on a perfectly flat substrate upon the action of a chemical gradient appears to be a natural consequence of the considered situation, we show that the behavior of a droplet on a gradient of topography is less obvious. Nevertheless, if care is taken in the choice of the topographic patterns (in order to reduce hysteresis effects), a motion may be observed. Interestingly, in this case, simple scaling arguments adequately account for the dependence of the droplet velocity on the roughness gradient (Moradi et al 2010 Europhys. Lett. 89 26006). Another issue addressed in this paper is the behavior of droplets on hydrophobic substrates with a periodic arrangement of square shaped pillars. Here, it is possible to propose an analytically solvable model for the case where the droplet size becomes comparable to the roughness scale (Gross et al 2009 Europhys. Lett. 88 26002). Two important predictions of the model are highlighted here. (i) There exists a state with a finite penetration depth, distinct from the full wetting (Wenzel) and suspended (Cassie-Baxter, CB) states. (ii) Upon quasi-static evaporation, a droplet initially on the top of the pillars (CB state) undergoes a transition to this new state with a finite penetration depth but then (upon further evaporation) climbs up the pillars and goes back to the CB state again. These predictions are confirmed via independent numerical simulations. Moreover, we also address the fundamental issue of the internal droplet dynamics and the terminal center of mass velocity on a flat substrate.

  4. Analytical expression for the exit probability of the q -voter model in one dimension

    NASA Astrophysics Data System (ADS)

    Timpanaro, André M.; Galam, Serge

    2015-07-01

    We present in this paper an approximation that is able to give an analytical expression for the exit probability of the q -voter model in one dimension. This expression gives a better fit for the more recent data about simulations in large networks [A. M. Timpanaro and C. P. C. do Prado, Phys. Rev. E 89, 052808 (2014), 10.1103/PhysRevE.89.052808] and as such departs from the expression ρ/qρq+(1-ρ ) q found in papers that investigated small networks only [R. Lambiotte and S. Redner, Europhys. Lett. 82, 18007 (2008), 10.1209/0295-5075/82/18007; P. Przybyła et al., Phys. Rev. E 84, 031117 (2011), 10.1103/PhysRevE.84.031117; F. Slanina et al., Europhys. Lett. 82, 18006 (2008), 10.1209/0295-5075/82/18006]. The approximation consists in assuming a large separation on the time scales at which active groups of agents convince inactive ones and the time taken in the competition between active groups. Some interesting findings are that for q =2 we still have ρ/2ρ2+(1-ρ ) 2 as the exit probability and for q >2 we can obtain a lower-order approximation of the form ρ/sρs+(1-ρ ) s with s varying from q for low values of q to q -1/2 for large values of q . As such, this work can also be seen as a deduction for why the exit probability ρ/qρq+(1-ρ ) q gives a good fit, without relying on mean-field arguments or on the assumption that only the first step is nondeterministic, as q and q -1/2 will give very similar results when q →∞ .

  5. Hexagonal AlN: Dimensional-crossover-driven band-gap transition

    NASA Astrophysics Data System (ADS)

    Bacaksiz, C.; Sahin, H.; Ozaydin, H. D.; Horzum, S.; Senger, R. T.; Peeters, F. M.

    2015-02-01

    Motivated by a recent experiment that reported the successful synthesis of hexagonal (h ) AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013), 10.1063/1.4851239], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of h -AlN by using first-principles calculations. We show that the hexagonal phase of the bulk h -AlN is a stable direct-band-gap semiconductor. The calculated phonon spectrum displays a rigid-layer shear mode at 274 cm-1 and an Eg mode at 703 cm-1, which are observable by Raman measurements. In addition, single-layer h -AlN is an indirect-band-gap semiconductor with a nonmagnetic ground state. For the bilayer structure, A A' -type stacking is found to be the most favorable one, and interlayer interaction is strong. While N -layered h -AlN is an indirect-band-gap semiconductor for N =1 -9 , we predict that thicker structures (N ≥10 ) have a direct band gap at the Γ point. The number-of-layer-dependent band-gap transitions in h -AlN is interesting in that it is significantly different from the indirect-to-direct crossover obtained in the transition-metal dichalcogenides.

  6. Dirac cones in artificial structures of 3d transitional-metals doped Mg-Al spinels

    SciTech Connect

    Lu, Yuan; Zuo, Xu; Feng, Min; Shao, Bin

    2014-05-07

    Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promising route for engineering Dirac physics in condensed matters.

  7. Dirac cones in artificial structures of 3d transitional-metals doped Mg-Al spinels

    NASA Astrophysics Data System (ADS)

    Lu, Yuan; Feng, Min; Shao, Bin; Zuo, Xu

    2014-05-01

    Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promising route for engineering Dirac physics in condensed matters.

  8. Molecular dynamics simulations of laser induced surface melting in orthorhombic Al13Co4

    NASA Astrophysics Data System (ADS)

    Sonntag, S.; Roth, J.; Trebin, H.-R.

    2010-10-01

    Laser induced surface melting of the aluminum-cobalt alloy Al13Co4 is investigated. For the simulations of the lattice ions we use molecular dynamics, while for the time evolution of the electron temperature a generalized heat-conduction equation is solved. Energy transfer between the sub-systems is allowed by an electron-phonon coupling term. This combined treatment of the electronic and atomic systems is an extension of the well-known two-temperature model [Anisimov et al. in JETP Lett. 39(2), 1974]. The alloy shows large structural affinity to decagonal quasicrystals, which have an in-plane five-fold symmetry,while in perpendicular direction the planes are stacked periodically. As a consequence we observe slight anisotropic melting behavior.

  9. Ancient hybrid origin of the eastern wolf not yet off the table: a comment on Rutledge et al. (2015)

    PubMed Central

    2016-01-01

    A recent study of North American canids by Rutledge et al. (Biol. Lett. 11, 20150303 (doi:10.1098/rsbl.2015.0303)) refutes the hypothesized hybrid origin of the eastern wolf (EW) based on genomic evidence against very recent hybridization. However, the analyses do not rule out the possibility of more ancient hybridization. Claims to have resolved the evolutionary origin of the EW are therefore inappropriate. Importantly, though, we plead that uncertainty about the ancient history of the taxon should not affect current conservation policy. PMID:26843554

  10. Ancient hybrid origin of the eastern wolf not yet off the table: a comment on Rutledge et al. (2015).

    PubMed

    Sefc, Kristina M; Koblmüller, Stephan

    2016-02-01

    A recent study of North American canids by Rutledge et al. (Biol. Lett. 11, 20150303 (doi:10.1098/rsbl.2015.0303)) refutes the hypothesized hybrid origin of the eastern wolf (EW) based on genomic evidence against very recent hybridization. However, the analyses do not rule out the possibility of more ancient hybridization. Claims to have resolved the evolutionary origin of the EW are therefore inappropriate. Importantly, though, we plead that uncertainty about the ancient history of the taxon should not affect current conservation policy.

  11. Genetic testing in ALS

    PubMed Central

    McLaughlin, Russell L.; Heverin, Mark; Thorpe, Owen; Abrahams, Sharon; Al-Chalabi, Ammar; Hardiman, Orla

    2017-01-01

    Objective: To determine the degree of consensus among clinicians on the clinical use of genetic testing in amyotrophic lateral sclerosis (ALS) and the factors that determine decision-making. Methods: ALS researchers worldwide were invited to participate in a detailed online survey to determine their attitudes and practices relating to genetic testing. Results: Responses from 167 clinicians from 21 different countries were analyzed. The majority of respondents (73.3%) do not consider that there is a consensus definition of familial ALS (FALS). Fifty-seven percent consider a family history of frontotemporal dementia and 48.5% the presence of a known ALS genetic mutation as sufficient for a diagnosis of FALS. Most respondents (90.2%) offer genetic testing to patients they define as having FALS and 49.4% to patients with sporadic ALS. Four main genes (SOD1, C9orf72, TARDBP, and FUS) are commonly tested. A total of 55.2% of respondents would seek genetic testing if they had personally received a diagnosis of ALS. Forty-two percent never offer presymptomatic testing to family members of patients with FALS. Responses varied between ALS specialists and nonspecialists and based on the number of new patients seen per year. Conclusions: There is a lack of consensus among clinicians as to the definition of FALS. Substantial variation exists in attitude and practices related to genetic testing of patients and presymptomatic testing of their relatives across geographic regions and between experienced specialists in ALS and nonspecialists. PMID:28159885

  12. Ventilatory Control in ALS

    PubMed Central

    Nichols, Nicole L.; Van Dyke, J.; Nashold, L.; Satriotomo, I.; Suzuki, M.; Mitchell, G.S.

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to “fight back” via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients. PMID:23692930

  13. Nonlinear diffusion of indirect excitons in an ideal bilayer with an in-plane harmonic trap

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Qinglu

    2009-06-01

    The nonlinear diffusion of the spatially indirect excitons in an ideal bilayer with an in-plane harmonic trap is investigated based on the theories developed by Ivanov [A.L. Ivanov, Europhys. Lett. 59 (2002) 586; A.L. Ivanov, J. Phys.: Condens. Matter 16 (2004) S3629] and Rapaport et al. [R. Rapaport, G. Chen, S. Simon, O. Mitrofanov, L. Pfeiffer, P.M. Platzman, Phys. Rev. B 72 (2005) 075428]. A nonlinear equation for the diffusion of the indirect excitons in this structure is established. The two-dimensional density of the indirect excitons in this structure is calculated. The calculations show that the density adjacent to the trap center for different exciton temperatures can remain very high even long after the photo-excitation because of the confinement of the in-plane harmonic trap, and that the indirect excitons gather several tens of μm away from the trap center. The calculations are in good agreement qualitatively with the experimental results of Voros et al. [Z. Voros, D.W. Snoke, L. Pfeiffer, K. West, Phys. Rev. Lett. 97 (2006) 016803] and prove that an in-plane harmonic trap can indeed keep an exciton gas dense near its center.

  14. Dissipative Particle Dynamics at Isothermal Conditions Using Shardlow-Like Splitting Algorithms

    DTIC Science & Technology

    2013-09-01

    15, 16), den Otter -Clarke integrator (17), first- and second- order Shardlow-splitting algorithms (SSAs) (18), and Lowe-Andersen integrator (19). Still...den Otter , W. K.; Clarke, J. H. R. A New Algorithm for Dissipative Particle Dynamics. Europhys. Lett. 2001, 53, 426. 18. Shardlow, T. Splitting

  15. Dissipative Particle Dynamics at Isoenthalpic Conditions Using Shardlow-Like Splitting Algorithms

    DTIC Science & Technology

    2013-09-01

    Dissipative Particle Dynamics With Energy Conservation. Europhys. Lett. 1997, 40 (2), 141. 2. Español , P. Dissipative Particle Dynamics With Energy...18. Ripoll, M.; Español , P.; Ernst, M. H. Dissipative Particle Dynamics with Energy Conservation: Heat Conduction. Int. J. Mod. Phys. C 1998, 9 (8

  16. Reflectance Effects Caused by Refractive Index Gradients in Diamond Cell Samples of H2 and Al2O3

    NASA Astrophysics Data System (ADS)

    Mao, Ho-Kwang; Eggert, Jon H.; Hemley, Russell J.

    At high pressures, optical spectroscopic techniques are the principal means for probing dense solid hydrogen, including both its vibrational and electronic excitations. Ruoff et al. [Phys. Rev. B47, 11039 (1993)] proposed that refractive index gradients of H2 samples loaded with 5% Al2O3 powder in diamond anvil cells could cause a 4% rise in infrared reflectivity which interfered with the measurements on hydrogen reported by Mao et al. [Phys. Rev. Lett. 65, 484 (1990)]. We have analyzed this alternative proposal, including computer simulations of the appropriate sample configuration. Our calculations show that effects of a graded index on the rise of reflectivity from 1.0 to 0.5 eV are less than 0.1% and are therefore insignificant.

  17. Reply to the comment on `Pople versus Dunning basis-sets for group IA metal hydrides and some other second row hydrides: The case against a De Facto standard' by R.A. Klein and M.A. Zottola [Chem. Phys. Lett. 419 (2006) 254--258

    NASA Astrophysics Data System (ADS)

    Klein, Roger A.; Zottola, Mark A.

    2006-10-01

    In their Comment on our recent Letter [R.A. Klein, M.A. Zottola, Chem. Phys. Lett. 419 (2006) 254-258], Feller and Peterson point out that density functional theory combined with the Pople triple split-valence basis-set 6-311++G(2d,p), does indeed perform well in comparison to second-order perturbation and coupled cluster theory in combination with correlation-consistent basis-sets for the prediction of bond lengths and harmonic frequencies but does not provide acceptable accuracy for dissociation energies. MPW1PW91/6-311++G(2d,p) is, therefore, highly suitable and computationally efficient for generating starting structures for subsequent single-point (SP) calculations at higher and more computationally expensive levels of theory.

  18. ALS2 mutations

    PubMed Central

    Schneider, Susanne A.; Carr, Lucinda; Deuschl, Guenther; Hopfner, Franziska; Stamelou, Maria; Wood, Nicholas W.; Bhatia, Kailash P.

    2014-01-01

    Objective: To determine the genetic etiology in 2 consanguineous families who presented a novel phenotype of autosomal recessive juvenile amyotrophic lateral sclerosis associated with generalized dystonia. Methods: A combination of homozygosity mapping and whole-exome sequencing in the first family and Sanger sequencing of candidate genes in the second family were used. Results: Both families were found to have homozygous loss-of-function mutations in the amyotrophic lateral sclerosis 2 (juvenile) (ALS2) gene. Conclusions: We report generalized dystonia and cerebellar signs in association with ALS2-related disease. We suggest that the ALS2 gene should be screened for mutations in patients who present with a similar phenotype. PMID:24562058

  19. Lou Gehrig's Disease (ALS)

    MedlinePlus

    ... when it becomes necessary. For instance, a power wheelchair can enable a paralyzed person with ALS to ... done these things despite being confined to a wheelchair for many years, being able to move only ...

  20. Genetic Testing for ALS

    MedlinePlus

    ... Involved Donate Familial Amyotrophic Lateral Sclerosis (FALS) and Genetic Testing By Deborah Hartzfeld, MS, CGC, Certified Genetic ... guarantee a person will develop symptoms of ALS. Genetic Counseling If there is more than one person ...

  1. Ag-Al-Ca

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Ag-Al-Ca' with the content:

  2. Dynamical screening effects in correlated electron materials-a progress report on combined many-body perturbation and dynamical mean field theory: 'GW + DMFT'.

    PubMed

    Biermann, Silke

    2014-04-30

    We give a summary of recent progress in the field of electronic structure calculations for materials with strong electronic Coulomb correlations. The discussion focuses on developments beyond the by now well established combination of density functional and dynamical mean field theory dubbed 'LDA + DMFT'. It is organized around the description of dynamical screening effects in the solid. Indeed, screening in the solid gives rise to dynamical local Coulomb interactions U(ω) (Aryasetiawan et al 2004 Phys. Rev. B 70 195104), and this frequency dependence leads to effects that cannot be neglected in a truly first principles description. We review the recently introduced extension of LDA + DMFT to dynamical local Coulomb interactions 'LDA + U(ω) + DMFT' (Casula et al 2012 Phys. Rev. B 85 035115, Werner et al 2012 Nature Phys. 1745-2481). A reliable description of dynamical screening effects is also a central ingredient of the 'GW + DMFT' scheme (Biermann et al 2003 Phys. Rev. Lett. 90 086402), a combination of many-body perturbation theory in Hedin's GW approximation and dynamical mean field theory. Recently, the first GW + DMFT calculations including dynamical screening effects for real materials have been achieved, with applications to SrV O3 (Tomczak et al 2012 Europhys. Lett. 100 67001, Tomczak et al Phys. Rev. B submitted (available electronically as arXiv:1312.7546)) and adatom systems on surfaces (Hansmann et al 2013 Phys. Rev. Lett. 110 166401). We review these and comment on further perspectives in the field. This review is an attempt to put elements of the original works into the broad perspective of the development of truly first principles techniques for correlated electron materials.

  3. A path to enhanced supercurrent conduction in YBaCuO: grain boundary doping

    NASA Astrophysics Data System (ADS)

    Mannhart, Jochen

    2001-03-01

    By doping, critical currents of grain boundaries in high-Tc superconductors can be significantly enhanced at all temperatures up to Tc, which was shown for the example of Ca-doping of YBCO [1-3]. This technology is seen as a promising candidate to enhance the performance of high-Tc wires and tapes, fabricated, e.g., by the coated conductor technology. In the presentation I will summarize experiments performed to assess the doping-induced Jc enhancement in view of these applications. Further, the status of studies performed to analyze the mechanisms by which the dopants act on the grain boundaries will be presented. This work was performed in collaboration with H. Bielefeldt, B. Goetz, G. Hammerl, H. Hilgenkamp, A. Schmehl, C. W. Schneider, and R. R. Schulz. Financial support by the BMBF (project EKM 13N6918) is gratefully acknowledged. References: [1] A. Schmehl et al., Europhys. Lett. 47, 110 (1999); [2] G. Hammerl et al., Nature 407, 162 (2000); [3] G. Daniels et al., Appl. Phys. Lett. 77, 3251 (2000).

  4. h -AlN-Mg(OH)2 van der Waals bilayer heterostructure: Tuning the excitonic characteristics

    NASA Astrophysics Data System (ADS)

    Bacaksiz, C.; Dominguez, A.; Rubio, A.; Senger, R. T.; Sahin, H.

    2017-02-01

    Motivated by recent studies that reported the successful synthesis of monolayer Mg (OH) 2 [Suslu et al., Sci. Rep. 6, 20525 (2016), 10.1038/srep20525] and hexagonal (h -)AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013), 10.1063/1.4851239], we investigate structural, electronic, and optical properties of vertically stacked h -AlN and Mg (OH) 2 , through ab initio density-functional theory (DFT), many-body quasiparticle calculations within the GW approximation and the Bethe-Salpeter equation (BSE). It is obtained that the bilayer heterostructure prefers the A B' stacking having direct band gap at the Γ with Type-II band alignment in which the valance band maximum and conduction band minimum originate from different layer. Regarding the optical properties, the imaginary part of the dielectric function of the individual layers and heterobilayer are investigated. The heterobilayer possesses excitonic peaks, which appear only after the construction of the heterobilayer. The lowest three exciton peaks are analyzed in detail by means of band decomposed charge density and the oscillator strength. Furthermore, the wave function calculation shows that the first peak of the heterobilayer originates from spatially indirect exciton where the electron and hole localized at h -AlN and Mg (OH) 2 , respectively, which is important for the light harvesting applications.

  5. Statins: Do They Cause ALS?

    MedlinePlus

    Statins: Do they cause ALS? Do statins cause amyotrophic lateral sclerosis (ALS)? Answers from Francisco Lopez-Jimenez, M.D. ... D. References Sorensen HT, et al. Statins and amyotrophic lateral sclerosis: The level of evidence for an association. Journal ...

  6. Rapidly solidified NiAl and FeAl

    NASA Technical Reports Server (NTRS)

    Gaydosh, D. J.; Crimp, M. A.

    1984-01-01

    Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

  7. ALS superbend magnet system

    SciTech Connect

    Zbasnik, J.; Wang, S.T.; Chen, J.Y.; DeVries, G.J.; DeMarco, R.; Fahmie, M.; Geyer, A.; Green, M.A.; Harkins, J.; Henderson, T.; Hinkson, J.; Hoyer, E.H.; Krupnick, J.; Marks, S.; Ottens, F.; Paterson, J.A.; Pipersky, P.; Portmann, G.; Robin, D.A.; Schlueter, R.D.; Steier, C.; Taylor, C.E.; Wahrer, R.

    2000-09-15

    The Lawrence Berkeley National Laboratory is preparing to upgrade the Advanced Light Source (ALS) with three superconducting dipoles (Superbends). In this paper we present the final magnet system design which incorporates R&D test results and addresses the ALS operational concerns of alignment, availability, and economy. The design incorporates conduction-cooled Nb-Ti windings and HTS current leads, epoxy-glass suspension straps, and a Gifford-McMahon cryocooler to supply steady state refrigeration. We also present the current status of fabrication and testing.

  8. Fosetyl-al

    Integrated Risk Information System (IRIS)

    Fosetyl - al ; CASRN 39148 - 24 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  9. Al Shanker Remembers.

    ERIC Educational Resources Information Center

    American Educator, 2000

    2000-01-01

    In a 1996 interview shortly before his death, Al Shanker, longtime president of the American Federation of Teachers, discussed such topics as: his own educational experiences; how he learned about political fighting in the Boy Scouts; the appeal of socialism; multinational corporations and the nation state; teaching tough students; and John Dewey…

  10. Al Partitioning Patterns and Root Growth as Related to Al Sensitivity and Al Tolerance in Wheat.

    PubMed Central

    Samuels, T. D.; Kucukakyuz, K.; Rincon-Zachary, M.

    1997-01-01

    Studies of Al partitioning and accumulation and of the effect of Al on the growth of intact wheat (Triticum aestivum L.) roots of cultivars that show differential Al sensitivity were conducted. The effects of various Al concentrations on root growth and Al accumulation in the tissue were followed for 24 h. At low external Al concentrations, Al accumulation in the root tips was low and root growth was either unaffected or stimulated. Calculations based on regression analysis of growth and Al accumulation in the root tips predicted that 50% root growth inhibition in the Al-tolerant cv Atlas 66 would be attained when the Al concentrations were 105 [mu]M in the nutrient solution and 376.7 [mu]g Al g-1 dry weight in the tissue. In contrast, in the Al-sensitive cv Tam 105, 50% root growth inhibition would be attained when the Al concentrations were 11 [mu]M in the nutrient solution and 546.2 [mu]g Al g-1 dry weight in the tissue. The data support the hypotheses that differential Al sensitivity correlates with differential Al accumulation in the growing root tissue, and that mechanisms of Al tolerance may be based on strategies to exclude Al from the root meristems. PMID:12223623

  11. Al Sumelat Water Network. Village of Al Sumelat, Iraq

    DTIC Science & Technology

    2006-03-15

    OFFICE OF THE SPECIAL INSPECTOR GENERAL FOR IRAQ RECONSTRUCTION AL SUMELAT WATER NETWORK VILLAGE OF AL SUMELAT, IRAQ...Sumelat Water Network Village of Al Sumelat, Iraq 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...Al Sumelat Water Network Village of Al Sumelat, Iraq Synopsis Introduction. This report was previously provided on a limited distribution basis

  12. Electronic energy dissipation during scattering of vibrationally excited molecules at metal surfaces: ab initio simulations for HCl/Al(111).

    PubMed

    Grotemeyer, Michael; Pehlke, Eckhard

    2014-01-31

    In this Letter, ab initio molecular dynamics simulations based on time-dependent density functional theory for the electrons and Ehrenfest dynamics for the nuclei are reported that detail the interaction of a vibrating HCl molecule with an Al(111) substrate. The mechanism responsible for the strong electron-hole-pair (EHP)-vibrational coupling in case of highly vibrationally excited molecules is traced back to a large eigenenergy shift of the spz*-like antibonding HCl lowest unoccupied molecular orbital with the bond length. As a consequence of this mechanism, the electronic excitation spectra turn out to be highly asymmetric. The simulations suggest an explanation of how to reconcile a strong EHP-vibrational coupling in case of highly vibrationally excited molecules with the small, but clearly evident, electronic contribution to the v=0 → v=1 vibrational excitation observed experimentally during the scattering of HCl molecules at a hot Au surface by Ran et al. [Phys. Rev. Lett. 98 237601 (2007)].

  13. Probing and modelling the localized self-mixing in a GaN/AlGaN field-effect terahertz detector

    NASA Astrophysics Data System (ADS)

    Sun, J. D.; Qin, H.; Lewis, R. A.; Sun, Y. F.; Zhang, X. Y.; Cai, Y.; Wu, D. M.; Zhang, B. S.

    2012-04-01

    In our previous work [Sun et al., Appl. Phys. Lett. 100, 013506 (2012)], we inferred the existence of localized self-mixing in an antenna-coupled field-effect terahertz detector. In this Letter, we report a quasistatic self-mixing model taking into account the localized terahertz fields and its verification by comparing the simulated results with the experimental data in a two-dimensional space of the gate voltage and the drain/source bias. The model well describes the detector characteristics: not only the magnitude, but also the polarity, of the photocurrent can be tuned. The existence of strongly localized self-mixing in such detectors is confirmed.

  14. On the range of validity of the fluctuation theorem for stochastic Markovian dynamics

    NASA Astrophysics Data System (ADS)

    Rákos, A.; Harris, R. J.

    2008-05-01

    We consider the fluctuations of generalized currents in stochastic Markovian dynamics. The large deviations of current fluctuations are shown to obey a Gallavotti-Cohen (GC) type symmetry in systems with a finite state space. However, this symmetry is not guaranteed to hold in systems with an infinite state space. A simple example of such a case is the zero-range process (ZRP). Here we discuss in more detail the already reported (Harris et al 2006 Europhys. Lett. 75 227) breakdown of the GC symmetry in the context of the ZRP with open boundaries and we give a physical interpretation of the phases that appear. Furthermore, the earlier analytical results for the single-site case are extended to cover multiple-site systems. We also use our exact results to test an efficient numerical algorithm of Giardinà et al (2006 Phys. Rev. Lett. 96 120603), which was developed to measure the current large deviation function directly. We find that this method breaks down in some phases which we associate with the gapless spectrum of an effective Hamiltonian.

  15. Study of the Linewidths of Excitonic Luminescence Transitions in AlGaN Alloys

    NASA Astrophysics Data System (ADS)

    Bajaj, K. K.; Coli, Giuliano; Li, J.; Lin, Jingyu; Jiang, H. X.

    2001-03-01

    We have investigated the linewidth of excitonic photoluminescence transitions at 10 K and as a function of Al concentration in AlGaN alloys grown by low-pressure metal organic chemical vapor deposition on (0001) oriented sapphire substrates, with low-temperature GaN buffer layers. Al composition ranged from 0 to 35 percent. By means of a lineshape analysis of the excitonic transition we identify the contribution of the compositional disorder in the alloy to the excitonic linewidth and find that the values of the excitonic linewidths in our samples are considerably smaller than those reported recently[1]. These values of the excitonic linewidths, as expected, increase as a function of Al concentration and agree very well with those calculated by a model presented by Lee and Bajaj[2]. [1] G. Steude, B.K. Meyer, A. Göldner, A. Hoffmann, F. Bertram, J.Christen, H. Amano and I. Akasaki, Appl. Phys. Lett 74, 2456 (1999) [2] S. M. Lee and K. K. Bajaj, J. Appl. Phys. 73, 1788 (1993)

  16. ALS insertion devices

    NASA Astrophysics Data System (ADS)

    Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W. V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

    1991-08-01

    The Advanced Light Source (ALS), the first US third generation synchrotron radiation source, is currently under construction at the Lawrence Berkeley Laboratory. The low-emittance, 1.5 GeV electron storage ring and the insertion devices are specifically designed to produce high brightness beams in the UV to soft X-Ray range. The planned initial complement of insertion devices includes four 4.6 m long undulators, with period lengths of 3.9 cm, 5.0 cm (2) and 8.0 cm, and a 2.9 m long wiggler of 16 cm period length. Undulator design is well advanced and fabrication has begun on the 5.0 cm and 8.0 cm period length undulators. This paper discusses ALS insertion device requirements; general design philosophy; and design of the magnetic structure, support structure/drive systems, control system and vacuum system.

  17. Beta-decay of proton-rich nucleus ^23Al and astrophysical consequences

    NASA Astrophysics Data System (ADS)

    Zhai, Y. J.; Iacob, V. E.; Al-Abdullah, T.; Fu, C.; Hardy, J. C.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Tribble, R. E.

    2006-04-01

    We will present the results of a β-decay study that was motivated by a nuclear astrophysics problem. For the first time γ-rays have been observed following the β decay of pure samples of ^23Al. We used the ^1H(^24Mg,2n)^23Al reaction and the MARS recoil separator of Texas A&M University. β and β-γ coincidence measurements were made with a fast tape-transport system and β and γ-ray detectors. The experiment allowed us to measure β branching ratios and deduce logft values for transitions to 14 final states in ^23Mg, including the isobaric analog state, and from them to determine unambigously the spin and parity of ^23Al ground state to be J^π=5/2^+. We will discuss how this excludes the large increase in the radiative proton-capture cross section for the reaction ^22Mg(p,γ)^23Al at astrophysical energies which was implied by claims that the spin and parity is J^π=1/2^+ [1,2], claims that motivated this study in the first place. The reaction is possible candidate to explain why space-based gamma-ray telescopes do not observe γ-rays from the decay of long-lived ^22Na formed in ONe novae explosions [3]: a larger cross section would be required to divert significant flux from the A=22 into the A=23 mass chain. [1] X. Z. Cai et al, Phys. Rev. C 65, 024610 (2002). [2] H.-Y. Zhang et al., Chin. Phys. Lett. 19, 1599 (2002). [3] M. Wiescher et al., Astrophys. J. 343, 352 (1989).

  18. Structure and oscillational motion of /sup 57/Fe atoms in interstitial sites in Al as determined from interference of Moessbauer. gamma. radiation

    SciTech Connect

    Pauling, L.

    1981-12-01

    The first excited site of the /sup 57/Fe atom entrapped in an interstitial site in aluminum, as reported by W. Petry, G. Vogl, and W. Mansel (Phys. Rev. Lett. 45, 1862 (1980)) from a Moessbauer spectroscopic study of a single crystal, is analyzed by consideration of the value of the Hooke's law constant of the Fe-Al bonds obtained from the values for elemental Fe and Al. The eight wavefunctions for the eightfold nearly degenerate excited state are described as 2s1p1d1f hybrids of three-dimensional harmonic oscillator wavefunctions relative to the center of the undistorted Al/sub 6/ octahedron or as localized 1s functions relative to the center of the distorted octahedron. These considerations provide a qualitative understanding of the observations on this system.

  19. Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: a discussion of the paper of Gurenko et al.

    NASA Astrophysics Data System (ADS)

    Day, James M. D.; Macpherson, Colin G.; Lowry, David; Pearson, D. Graham

    2012-07-01

    Gurenko et al. (Contrib Mineral Petrol 162:349-363, 2011) report laser-assisted fluorination (LF) and secondary ionization mass spectrometry (SIMS) 18O/16O datasets for olivine grains from the Canary Islands of Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro. As with prior studies of oxygen isotopes in Canary Island lavas (e.g. Thirlwall et al. Chem Geol 135:233-262, 1997; Day et al. Geology 37:555-558, 2009, Geochim Cosmochim Acta 74:6565-6589, 2010), these authors find variations in δ18Ool (~4.6-6.0 ‰) beyond that measured for mantle peridotite olivine (Mattey et al. Earth Planet Sci Lett 128:231-241, 1994) and interpret this variation to reflect contributions from pyroxenite-peridotite mantle sources. Furthermore, Gurenko et al. (Contrib Mineral Petrol 162:349-363, 2011) speculate that δ18Ool values for La Palma olivine grains measured by LF (Day et al. Geology 37:555-558, 2009, Geochim Cosmochim Acta 74:6565-6589, 2010) may be biased to low values due to the presence of altered silicate, possibly serpentine. The range in δ18Ool values for Canary Island lavas are of importance for constraining their origin. Gurenko et al. (Contrib Mineral Petrol 162:349-363, 2011) took a subset (39 SIMS analyses from 13 grains from a single El Hierro lava; EH4) of a more extensive dataset (321 SIMS analyses from 110 grains from 16 Canary Island lavas) to suggest that δ18Ool is weakly correlated ( R 2 = 0.291) with the parameter used by Gurenko et al. (Earth Planet Sci Lett 277:514-524, 2009) to describe the estimated weight fraction of pyroxenite-derived melt ( Xpx). With this relationship, end-member δ18O values for HIMU-peridotite (δ18O = 5.3 ± 0.3 ‰) and depleted pyroxenite (δ18O = 5.9 ± 0.3 ‰) were defined. Although the model proposed by Gurenko et al. (Contrib Mineral Petrol 162:349-363, 2011) implicates similar pyroxenite-peridotite mantle sources to those proposed by Day et al. (Geology 37:555-558, 2009, Geochim Cosmochim Acta 74:6565-6589, 2010

  20. Frequently Asked Questions about ALS and the ALS Registry

    MedlinePlus

    ... Why is it necessary to provide my Social Security Number (SSN) when registering in the National ALS ... Why is it necessary to provide my Social Security Number (SSN) when registering in the National ALS ...

  1. Al Jazirah, Sudan

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Al Jazirah (also Gezira) is one of the 26 states of Sudan. The state lies between the Blue Nile and the White Nile in the east-central region of the country. It is a well populated area suitable for agriculture. The area was at the southern end of Nubia and little is known about its ancient history and only limited archaeological work has been conducted in this area. The region has benefited from the Gezira Scheme, a program to foster cotton farming begun in 1925. At that time the Sennar Dam and numerous irrigation canals were built. Al Jazirah became the Sudan's major agricultural region with more than 2.5 million acres (10,000 km) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

    The image was acquired December 25, 2006, covers an area of 56 x 36.4 km, and is located near 14.5 degrees north latitude, 33.1 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  2. AL Amyloidosis and Agent Orange

    MedlinePlus

    ... for survivors' benefits . Research on AL amyloidosis and herbicides The Health and Medicine Division (formally known as ... to the compounds of interest found in the herbicide Agent Orange and AL amyloidosis." VA made a ...

  3. Al Qaeda as a System

    DTIC Science & Technology

    2006-03-15

    either as welcome guests or parasites . As welcome guests, Al Qaeda members take sanctuary in sponsor states. Sponsor states provide Al Qaeda with...sponsorship, Al Qaeda takes sanctuary as parasites either overtly or covertly. They take overt sanctuary in countries that publicly claim a policy...39 Yehudit Barsky, “Al Qa’ida, Iran, and Hezbollah: A Continuing Symbiosis ,” The American Jewish Committee Series on Terrorism , February 2004, 2-3

  4. Protein Aggregation Inhibitors for ALS Therapy

    DTIC Science & Technology

    2013-07-01

    well as the development of novel organic bases. Since then, he has been an instructor of chemistry at Northeastern Illinois University, teaching ...courses in general, organic, and more recently toxicological chemistry and pharmacology, in addition to teaching in the Urban Health Program at the...Tetrahedron Lett. 2013, 54, 573−575. (35) Becke, A. D. Density-functional thermochemistry . III. The role of exact exchange. J. Chem. Phys. 1993, 98, 5648−5652

  5. Hybrid density functional theory studies of AlN and GaN under uniaxial strain.

    PubMed

    Qin, Lixia; Duan, Yifeng; Shi, Hongliang; Shi, Liwei; Tang, Gang

    2013-01-30

    The structural stability, spontaneous polarization, piezoelectric response, and electronic structure of AlN and GaN under uniaxial strain along the [0001] direction are systematically investigated using HSE06 range-separated hybrid functionals. Our results exhibit interesting behavior. (i) AlN and GaN share the same structural transition from wurtzite to a graphite-like phase at very large compressive strains, similarly to other wurtzite semiconductors. Our calculations further reveal that this well-known phase transition is driven by the transverse-acoustic soft phonon mode associated with elastic instabilities. (ii) The applied tensile strain can either drastically suppress or strongly enhance the polarization and piezoelectricity, based on the value of the strain. Furthermore, large enhancements of polarization and piezoelectricity close to the phase-transition regions at large compressive strains are predicted, similar to those previously predicted in ferroelectric fields. Our calculations indicate that such colossal enhancements are strongly correlated to phase transitions when large atomic displacements are generated by external strains. (iii) Under the same strain, AlN and GaN have significantly different electronic properties: both wurtzite and graphite-like AlN always display direct band structures, while the the bandgap of wurtzite GaN is always direct and that of graphite-like GaN always indirect. Furthermore, the bandgap of graphite-like AlN is greatly enhanced by large compressive strain, but that of wurtzite GaN is not sensitive to compressive strain. Our results are drastically different from those for equibiaxial strain (Duan et al 2012 Appl. Phys. Lett. 100 022104).

  6. Hybrid density functional theory studies of AlN and GaN under uniaxial strain

    NASA Astrophysics Data System (ADS)

    Qin, Lixia; Duan, Yifeng; Shi, Hongliang; Shi, Liwei; Tang, Gang

    2013-01-01

    The structural stability, spontaneous polarization, piezoelectric response, and electronic structure of AlN and GaN under uniaxial strain along the [0001] direction are systematically investigated using HSE06 range-separated hybrid functionals. Our results exhibit interesting behavior. (i) AlN and GaN share the same structural transition from wurtzite to a graphite-like phase at very large compressive strains, similarly to other wurtzite semiconductors. Our calculations further reveal that this well-known phase transition is driven by the transverse-acoustic soft phonon mode associated with elastic instabilities. (ii) The applied tensile strain can either drastically suppress or strongly enhance the polarization and piezoelectricity, based on the value of the strain. Furthermore, large enhancements of polarization and piezoelectricity close to the phase-transition regions at large compressive strains are predicted, similar to those previously predicted in ferroelectric fields. Our calculations indicate that such colossal enhancements are strongly correlated to phase transitions when large atomic displacements are generated by external strains. (iii) Under the same strain, AlN and GaN have significantly different electronic properties: both wurtzite and graphite-like AlN always display direct band structures, while the the bandgap of wurtzite GaN is always direct and that of graphite-like GaN always indirect. Furthermore, the bandgap of graphite-like AlN is greatly enhanced by large compressive strain, but that of wurtzite GaN is not sensitive to compressive strain. Our results are drastically different from those for equibiaxial strain (Duan et al 2012 Appl. Phys. Lett. 100 022104).

  7. Origin of the Inner Ring in Photoluminescence Patterns of Quantum Well Excitons

    DTIC Science & Technology

    2006-03-15

    855. [3] Hagn M., Zrenner A., Böhm G. and Weimann G., Appl. Phys. Lett., 67 (1995) 232. [4] Negoita V., Snoke D. W . and Eberl K., Phys. Rev. B, 60...418 (2002) 751. [7] Vörös Z., Balili R., Snoke D. W ., Pfeiffer L. and West K., Phys. Rev. Lett., 94 (2005) 226401. [8] Butov L. V., J. Phys...L., Littlewood P. B. and Haug H., Phys. Rev. B, 59 (1999) 5032. [12] Ivanov A. L., Europhys. Lett., 59 (2002) 586. [13] Butov L. V., Zrenner A

  8. Active Nematics Are Intrinsically Phase Separated

    NASA Astrophysics Data System (ADS)

    Mishra, Shradha; Ramaswamy, Sriram

    2006-09-01

    Two-dimensional nonequilibrium nematic steady states, as found in agitated granular-rod monolayers or films of orientable amoeboid cells, were predicted [Europhys. Lett. 62, 196 (2003)EULEEJ0295-507510.1209/epl/i2003-00346-7] to have giant number fluctuations, with the standard deviation proportional to the mean. We show numerically that the steady state of such systems is macroscopically phase separated, yet dominated by fluctuations, as in the Das-Barma model [Phys. Rev. Lett. 85, 1602 (2000)PRLTAO0031-900710.1103/PhysRevLett.85.1602]. We suggest experimental tests of our findings in granular and living-cell systems.

  9. Is there a Climate Network - A Backbone of the Climate System? (Invited)

    NASA Astrophysics Data System (ADS)

    Kurths, J.

    2010-12-01

    We consider an inverse problem: Is there a backbone-like structure underlying the climate system? For this we propose a method to reconstruct and analyze a complex network from data generated by a spatio-temporal dynamical system. This technique is then applied to reanalysis and model surface air temperature data. Parameters of this network, as betweenness centrality, uncover relations to global circulation patterns in oceans and atmosphere. We especially study the role of hubs and of long range connections, called teleconnections, in the flows of energy and matter in the climate system. The global scale view on climate networks offers promising new perspectives for detecting dynamical structures based on nonlinear physical processes in the climate system. References Arenas, A., A. Diaz-Guilera, J. Kurths, Y. Moreno, and C. Zhou, Phys. Reports 2008, 469, 93. Donges, J., Y. Zou, N. Marwan, and J. Kurths, Europ. Phys. J. ST 2009, 174, 157-179. Donges, J., Y. Zou, N. Marwan, and J. Kurths, Europhys. Lett. 2009, 87, 48007. Nawrath, J. et al., Phys. Rev. Lett. 2010, 104, 038701. Donner, R., Y. Zou, J. Donges, N. Marwan, and J. Kurths, Phys. Rev. E 2010, 81, 015101(R ).

  10. Decrease of pairing strength with underdoping in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Chang, Johan

    2012-02-01

    The transition temperature Tc of cuprate superconductors decreases at low hole doping p, but it is still unclear whether the pairing strength decreases or increases. Different interpretations of the pseudogap lead to opposite conclusions. Different estimates of the upper critical field Hc2 are in sharp contradiction. In this talk, we resolve the latter contradiction by showing that superconducting fluctuations in the underdoped cuprate Eu-LSCO, measured via the Nernst effect, obey the theory of Gaussian fluctuations, as in conventional superconductors [1, 2]. The extracted critical field Hc2 is small, and it dips at p = 0.11, showing that pairing strength is weak where stripe order is strong. In the archetypal cuprate superconductor YBCO, Hc2 extracted from other measurements [3] has the same doping dependence, also with a minimum at p = 0.11, again where stripe order is present [4, 5]. We conclude that competing states such as stripe order weaken the pairing strength and this, rather than phase fluctuations, is the predominant cause for the low Tc of underdoped cuprates. Work done in collaboration with N. Doiron-Leyraud, E. Hassinger, J.-Ph. Reid, O. Cyr-Choinière, F. Lalibert'e, R. Daou, S. Pyon, T. Takayama, H. Takagi, and Louis Taillefer. [4pt] [1] M. N. Serbyn et al., Phys. Rev. Lett. 102, 067001 (2009). [0pt] [2] K. Michaeli and A. M. Finkel'stein, Europhys. Lett. 86, 27007 (2009).[0pt] [3] Y. Ando and K. Segawa, Phys. Rev. Lett. 88, 167005 (2002).[0pt] [4] F. Lalibert'e et al., Nature Comm. 2, 432 (2011).[0pt] [5] T. Wu et al., Nature 477, 191 (2011).

  11. Microstructure and magnetic microstructure of the Pr 60Al 10Ni 10Cu 20-xFe x ( x=0, 4, 10, 15, 18) alloys observed by magnetic force microscopy

    NASA Astrophysics Data System (ADS)

    Pang, Z. Y.; Han, S. H.; Wang, Y. T.; Wang, W. H.; Han, B. S.

    2005-03-01

    The microstructure and magnetic microstructure of the Pr 60Al 10Ni 10Cu 20-xFe x ( x=0, 4, 10, 15, 18) alloys have been achieved simultaneously by employing a magnetic force microscope directly on the as-cast cylinder rod surface for the first time. By varying the content of Fe, the microstructure of the Pr-based alloy changes progressively from a full glassy state to a composite state with nanocrystalline particles embedded in the glassy matrix, and finally into a nanostructured state. The accompanying magnetic property gradually changes from paramagnetic to hard. The experiment directly evidences the existence of exchange coupling between the crystallites and the variety of the grain-size-dependent magnetic properties can be well explained by Löffler et al.'s new random-anisotropy model (Löffler, et al., Phys. Rev. Lett. 85 (9) (2000) 1990).

  12. Growth and Optical Properties of Al rich AlN/AlGaN Quantum Wells

    NASA Astrophysics Data System (ADS)

    Tahtamouni, T. M. Al; Nepal, N.; Nakarmi, M. L.; Lin, J. Y.; Jiang, H. X.

    2006-03-01

    Al rich AlGaN alloys are promising materials for the applications in the optoelectronic devices such as deep ultraviolet (UV) emitters and detectors in the spectral range down to 200 nm. AlGaN based UV emitters (λ<340nm) has applications in bio-chemical agent detection and medical research/ health care. To realize deep UV emission (λ< 280 nm) Al rich AlGaN based quantum wells (QWs) are required. We report here the growth of AlN/AlxGa1-xNQWs (x>0.65) on AlN/sapphire templates by metalorganic chemical vapor deposition (MOCVD). Deep UV photoluminescence (PL) was employed to study the optical properties of the QWs. Well width (Al composition) dependence was studied by varying the QW thickness (Al composition) with fixed x ˜ 0.65 (well width at 3 nm). Optical properties of these QWs such as the effects of alloy fluctuation, temperature, strain and piezoelectric field, carrier and exciton localizations on the quantum efficiency have been studied. Carrier and exciton dynamics were probed. Implications of our findings on the applications of Al rich AlN/AlGaN QWs for UV emitters and detectors will also be discussed.

  13. Studies of 27Al NMR in SrAl4

    NASA Astrophysics Data System (ADS)

    Niki, Haruo; Higa, Nonoka; Kuroshima, Hiroko; Toji, Tatsuki; Morishima, Mach; Minei, Motofumi; Yogi, Mamoru; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika; Harima, Hisatomo

    A charge density wave (CDW) transition at TCDW = 243 K and a structural phase (SP) transition at approximately 100 K occur in SrAl4 with the BaAl4-type body center tetragonal structure, which is the divalent and non-4f electron reference compound of EuAl4. To understand the behaviors of the CDW and SP transitions, the 27Al NMR measurements using a single crystal and a powder sample of SrAl4 have been carried out. The line width below TCDW is modulated by an electrical quadruple interaction between 27Al nucleus and CDW charge modulation. The incommensurate CDW state below TCDW changes into a different structure below TSP. The temperature dependences of Knight shifts of 27Al(I) and 27Al(II) show the different behaviors. The temperature variation of 27Al(I) Knight shift shows anomalies at the CDW and SP transition temperatures, revealing the shift to negative side below TCDW, which is attributable to the core polarization of the d-electrons. However, 27Al(II) Knight shift keeps almost constant except for the small shift due to the SP transition. The 1/T1T of 27Al(I) indicates the obvious changes due to the CDW and SP transitions, while that of 27Al(II) takes a constant value. The density of state at the Fermi level at Al(I) site below 60 K would be about 0.9 times less than that above TCDW.

  14. Electron and Composite Fermion Transport in MOCVD Grown GaAs/AlGaAs Heterostructures

    NASA Astrophysics Data System (ADS)

    Zudov, M. A.; Du, R. R.; Simmons, J. A.; Chui, H. C.

    1996-03-01

    Previously, high quality fractional quantum Hall effect(FQHE) data was accessible only from MBE-grown heterostructures. Sandia National Labs has recently grown high purity MOCVD GaAs/AlGaAs heterostructure with 2DEG mobility of 2.0x10^6 cm^2/Vs[1]. Material parameters such as impurity potential profile, defects and interface quality are expected to be modified for MOCVD. While these are believed to affect predominantly the carrier scattering in 2DEG, their effects on quantum transport properties (in particular the experimental effective mass and spin g-factor of composite fermions) are also worth examination. We report on temperature-dependent Shubnikov -de Haas(SdH) oscillations near zero magnetic field, SdH near Landau level filling factor ν = 1/2, 3/2, and angular dependent magnetoresistance mesurements on the FQHE states around ν = 3/2 in high-density (up to 3.2x10^11 cm-2) MOCVD samples. Measurements were performed in a 20mK/20T ^3He-^4He mixture dilution refrigerator. Our results around ν = 3/2 conform to the same composite fermion level scheme obtained earlier for low-density MBE samples[2]. [1] H. C. Chui, B. E. Hammons, N. E. Harff, J. A. Simmons and M. E. Sherwin, to appear in Appl. Phys. Lett. [2] R. R. Du, A. S. Yeh, H. L. Stormer, D. C. Tsui, L. N. Pfeifer, K. W. West, Phys. Rev. Lett. 75, 3926(1995)

  15. Rub' al Khali, Arabia

    NASA Technical Reports Server (NTRS)

    2008-01-01

    The Rub' al Khali is one of the largest sand deserts in the world, encompassing most of the southern third of the Arabian Peninsula. It includes parts of Oman, United Arab Emirates, and Yemen. The desert covers 650,000 square kilometers, more than the area of France. Largely unexplored until recently, the desert is 1000 km long and 500 km wide. The first documented journeys made by Westerners were those of Bertram Thomas in 1931 and St. John Philby in 1932. With daytime temperatures reaching 55 degrees Celsius, and dunes taller than 330 meters, the desert may be one of the most forbidding places on Earth.

    The image was acquired December 2, 2005, covers an area of 54.8 x 61.9 km, and is located near 20.7 degrees north latitude, 53.6 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  16. Morton et al. Reply

    NASA Technical Reports Server (NTRS)

    Morton, Douglas C.; Nagol, Jyoteshwar; Carabajal, Claudia C.; Rosette, Jacqueline; Palace, Michael; Cook, Bruce D.; Vermote, Eric F.; Harding, David J.; North, Peter R. J.

    2016-01-01

    Multiple mechanisms could lead to up-regulation of dry-season photosynthesis in Amazon forests, including canopy phenology and illumination geometry. We specifically tested two mechanisms for phenology-driven changes in Amazon forests during dry-season months, and the combined evidence from passive optical and lidar satellite data was incompatible with large net changes in canopy leaf area or leaf reflectance suggested by previous studies. We therefore hypothesized that seasonal changes in the fraction of sunlit and shaded canopies, one aspect of bidirectional reflectance effects in Moderate Resolution Imaging Spectroradiometer (MODIS) data, could alter light availability for dry-season photosynthesis and the photosynthetic capacity of Amazon forests without large net changes in canopy composition. Subsequent work supports the hypothesis that seasonal changes in illumination geometry and diffuse light regulate light saturation in Amazon forests. These studies clarify the physical mechanisms that govern light availability in Amazon forests from seasonal variability in direct and diffuse illumination. Previously, in the debate over light limitation of Amazon forest productivity, seasonal changes in the distribution of light within complex Amazon forest canopies were confounded with dry-season increases in total incoming photosynthetically active radiation. In the accompanying Comment, Saleska et al. do not fully account for this confounding effect of forest structure on photosynthetic capacity.

  17. On the effect of the barrier widths in the InAs/AlSb/GaSb single-barrier interband tunneling structures

    NASA Astrophysics Data System (ADS)

    Chen, J. F.; Yang, L.; Wu, M. C.; Chu, S. N. G.; Cho, A. Y.

    1990-10-01

    The dependence of the interband tunneling current on AlSb barrier widths is studied in the InAs/AlSb/GaSb single-barrier diode structures. The experimental results show that the peak current density displays an exponential dependence on the barrier width. The Wentzel-Kramers-Brillouin approximation combined with the kṡp two-band model were used in analyzing the energy level in the AlSb barrier through which the peak tunneling currents occur. The energy level thus obtained (0.48±0.10 eV above the valence band edge of the AlSb) agrees with the valence-band offset (0.40±0.15 eV) between the AlSb and the GaSb obtained by x-ray photoemission measurement reported by Gualtieri et al. [Appl. Phys. Lett. 49, 1037 (1986)]. By adjusting the barrier width properly, we obtained a high peak current density of 24 kA/cm2 (with a peak-to-valley ratio of 1.4) and a high peak-to-valley ratio of 4.5 (with a peak current density of 3.5 kA/cm2) at room temperature. In addition, the peak-current voltages for different AlSb barrier widths were calculated and compared with the measured results.

  18. Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

    SciTech Connect

    Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2011-06-15

    The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 x 10{sup 20}cm{sup -3}) into ZnO is performed using a multiple-step energy. The resistivity decreases from {approx}10{sup 4{Omega}} cm for un-implanted ZnO to 1.4 x 10{sup -1{Omega}} cm for as-implanted, and reaches 6.0 x 10{sup -4{Omega}} cm for samples annealed at 1000 deg. C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zn{sub i}) and O (O{sub i}), respectively. After annealing at 1000 deg. C, the Zn{sub i} related defects remain and the O{sub i} related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zn{sub i} ({approx}30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 deg. C is assigned to both of the Zn{sub i} related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 deg. C, suggesting electrically activated Al donors.

  19. Alexandria (Al Iskandariya), Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of Alexandria was taken by astronauts on board the International Space Station in December 2000 using an Electronic Still Camera. A wider-angle view (STS088-739-90) taken from the Space Shuttle in December 1998 is available for context. Alexandria (Al Iskandariya) occupies a T-shaped peninsula and strip of land separating the Mediterranean from Lake Mariout. Originally the town was built upon a mole (stone breakwater) called Heptastadium, which joined the island of Pharos (see referenced website, below) to the mainland. Since then sedimentary deposits have widened the mole. Since 1905, when the 370,000 Alexandrians lived in an area of about 4 sq km between the two harbors, the city (population 4 million; see referenced website, below) has grown beyond its medieval walls and now occupies an area of about 300 sq km. The Mahmudiya Canal, connecting Alexandria with the Nile, runs to the south of the city and, by a series of locks, enters the harbor of the principal port of Egypt (note ships). The reddish and ochre polygons west of Lake Mariout are salt-evaporation, chemical-storage, and water-treatment ponds within the coastal lagoon. Reference Youssef Halim and Fatma Abou Shouk, 2000, Human impacts on Alexandria's marine environment: UNESCO, Coastal Regions and Small Islands Unit (CSI), Coastal Management Sourcebooks 2 (accessed December 20, 2000) Additional photographs taken by astronauts can be viewed at NASA-JSC's Gateway to Astronaut Photography of Earth. Image ISS001-ESC-5025 provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center.

  20. Is there a paraneoplastic ALS?

    PubMed

    Corcia, Philippe; Gordon, Paul H; Camdessanche, Jean-Philippe

    2015-06-01

    Our objective was to examine the strength of evidence in support of the paraneoplastic syndrome (PNS) as one cause of ALS and, if the association appears more likely than chance, determine which features of ALS imply concurrent malignancy. We reviewed the literature on concurrent ALS and neoplasia assessing the strength of evidence for the association. Most accounts of ALS and neoplasm are case reports or small uncontrolled series. In order of strength of evidence, three clinical situations that support a paraneoplastic aetiology for ALS are: 1) laboratory evidence of well-characterized onconeuronal antibodies, most often anti-Hu, anti-Yo or anti-Ri; 2) co-occurrence of ALS and a neoplasm known to cause PNS, usually lymphoma or cancer of the breast; and 3) combined ALS and a neoplasm not classically associated with PNS, without detectable onconeuronal antibodies. Clinical features that warrant evaluation of neoplasm include upper motor neuron disease in elderly females, rapid progression, non-motor signs, and young onset. In conclusion, most examples of ALS and neoplasm do not constitute a classically established PNS. Rare instances of elevated onconeuronal antibody titres or typical neoplasm, implies that, albeit rare, the PNS is one of a multitude of causes of ALS.

  1. Mid-infrared pump-related electric-field domains in GaAs/(Al,Ga)As quantum-cascade structures for terahertz lasing without population inversion

    SciTech Connect

    Giehler, M.; Wienold, M.; Schrottke, L.; Hey, R.; Grahn, H. T.; Pavlov, S. G.; Huebers, H.-W.; Winnerl, S.; Schneider, H.

    2011-11-15

    We investigate the effect of mid-infrared (MIR) pumping on the transport properties of GaAs/(Al,Ga)As terahertz (THz) quantum lasers (TQLs), which rely on quantum coherence effects of intersubband transitions. Aiming at THz lasing at elevated temperatures, we extend the concept of THz gain with and without population inversion of a single, MIR-pumped, electrically driven THz stage proposed by Waldmueller et al.[Phys. Rev. Lett. 99, 117401 (2007)] to an entire TQL. However, experiments using a CO{sub 2} as well as a free-electron laser and numerical simulations show that this resonant MIR pumping causes a negative differential conductivity (NDC) in addition to the NDC caused by sequential tunneling. Lasing of these TQLs is prevented by the formation of electric-field domains below the resonance field strength for gain of each single THz stage.

  2. onHigh-peak-power strain-compensated GaInAs/AlInAs quantum cascade lasers (λ ˜4.6 μm) based on a slightly diagonal active region design

    NASA Astrophysics Data System (ADS)

    Yang, Q.; Lösch, R.; Bronner, W.; Hugger, S.; Fuchs, F.; Aidam, R.; Wagner, J.

    2008-12-01

    Employing a "slightly diagonal" active region design for the quantum cascade lasers compared to a reference sample based on the conventional vertical transition design [R. Köhler et al., Appl. Phys. Lett. 76, 1092 (2000)], we have improved the maximum operation temperature, room-temperature maximum peak power per facet, and room-temperature slope efficiency from 320 K, 200 mW, and 570 mW/A to higher than 360 K, 3.2 W, and 2200 mW/A, respectively, for the device size of 16 μm×3 mm with as-cleaved facets operated in pulsed mode.

  3. Impurity Enhancement of Al_2O_3/Al Adhesion

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Smith, John R.; Zhang, Wenqing; Evans, Anthony

    2003-03-01

    Our first-principles computations indicate that the clean Al_2O_3/Al interface is relatively weak - weaker than bulk Al. Fracture experiments reveal that the interface is relatively strong with observed failure in bulk Al, however. This paradox is resolved via doping effects of the common impurity C. We have found that only 1/3 of a monolayer of carbon segregated to the interface can increase the work of separation by a factor of 3. The resulting strong interface is consistent with fracture experiments. It arises due to void formation in the interface, which provides low-strain sites for the carbon to segregate to. The degree of void formation is consistent with the relatively high heat of oxide formation of Al.

  4. Investigations of the structural stability of highly strained [(Al)GaIn]As/Ga (PAs) multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Marschner, T.; Lutgen, S.; Volk, M.; Stolz, W.; Göbel, E. O.

    1996-10-01

    The structural stability of highly strained [(Al)GaIn]As/Ga (PAs) strained layer superlattice (SLS) structures as a function of the average lattice mismatch is investigated. The SLS structures, grown by metalorganic vapor-phase epitaxy, are studied by using high-resolution x-ray diffraction. The range of stable SLS structures obtained experimentally is compared to a recent theoretical model assuming strain relaxation by formation of misfit dislocations [D. C. Houghton, M. Davies, and M. Dion, Appl. Phys. Lett. 64, 505 (1994)]. In particular, the influence of the surface migration length of the group-III species on the growth surface is investigated by varying the Al concentration in the compressively strained [(Al)GaIn]As layers. Structurally stable [(Al)GaIn]As/Ga(PAs) SLS structures having a total layer thickness of 1 μm and an average lattice mismatch of up to (Δd/d)⊥=1.2×10-2 have been realized. These values exceed by far the values of the misfit dislocation model. This behavior indicates that surface morphology changes rather than misfit dislocation formation are the primary cause for the instability of highly strained SLSs.

  5. Thermal Modeling of Al-Al and Al-Steel Friction Stir Spot Welding

    NASA Astrophysics Data System (ADS)

    Jedrasiak, P.; Shercliff, H. R.; Reilly, A.; McShane, G. J.; Chen, Y. C.; Wang, L.; Robson, J.; Prangnell, P.

    2016-09-01

    This paper presents a finite element thermal model for similar and dissimilar alloy friction stir spot welding (FSSW). The model is calibrated and validated using instrumented lap joints in Al-Al and Al-Fe automotive sheet alloys. The model successfully predicts the thermal histories for a range of process conditions. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Fe welds. Temperature predictions were used to study the evolution of hardness of a precipitation-hardened aluminum alloy during post-weld aging after FSSW.

  6. Philosophieren als Unterrichtsprinzip im Mathematikunterricht

    NASA Astrophysics Data System (ADS)

    Meerwaldt, Diana

    Philosophieren und Mathematik scheinen zunächst gegensätzliche Bereiche zu sein, die sich kaum vereinbaren lassen. Dies trifft für eine Auffassung zu, die Philosophieren als "Gerede" disqualifiziert und Mathematik als eine reine "Formelwissenschaft" begreift. Beide Auffassungen werden den Gegenständen nicht gerecht.

  7. The Evolution of Al Qaeda

    DTIC Science & Technology

    2007-06-15

    Al Qaeda is a product of the forces of globalization. Increasing access to global finances , international travel, and sophisticated technology is...evolution. Al Qaeda is a product of the forces of globalization. Increasing access to global finances , international travel, and sophisticated technology...75 Finance

  8. Magneto-transport in InAs/AlGaSb open quantum dot structures

    NASA Astrophysics Data System (ADS)

    Maemoto, Toshihiko; Kobayashi, Tetsuji; Kitamura, Yoji; Karasaki, Moritomo; Kita, Toshihiro; Sasa, Shigehiko; Inoue, Masataka; Ishibashi, Koji; Aoyagi, Yoshinobu

    2001-03-01

    We report on the magneto-transport properties in InAs/AlGaSb open quantum dot structures, in which electron interference should be an important process. The open dot structures such as the square or circle cavities with sub-micron scale have been fabricated by electron beam lithography. Since the device size is small enough to be less than the elastic mean free path, the electron transport is expected to be predominantly ballistic in nature. Oscillations or fluctuations of magnetoresistance have been observed from low magnetic fields below 1 T, which were not seen in the conventional devices. The periodic fluctuations indicate the important effect of electric wave interference in the quantum dot structures. The large and simple structures of magnetoresistance fluctuations can be analyzed from the semi-classical scattering trajectory depending on the geometrical feature of the devices. In addition to these large-period magneto-oscillations, the short-period magnetoresistance fluctuations have been also observed even at 4.2K [1]. These fluctuations may result from the complex modes of the interference electron waves possibly characterized by highly characteristic wave function scattering [2]. From the analyses of correlation functions of these oscillations, interference of electron waves in the InAs/AlGaSb open quantum dot structures will be discussed. [1] T. Maemoto, M. Ichiu, A. Ohya, S. Sasa, M. Inoue, K. Ishibashi, Y. Aoyagi, Physica B 272, 110 (1999). [2] R. Akis, D. K. Ferry, and J. P. Bird, Phys. Rev. Lett. 79, 123 (1997).

  9. Characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al Tunnel Junctions

    SciTech Connect

    Petrovic, C.; Nevirkovets, I.P.; Chernyashevskyy, O.; Hu, R.; Ketterson, J.B.; Sarma, B.K.

    2009-03-03

    We report characteristics of CeCoIn{sub 5}/Al/AlO{sub x}/Nb and CeCoIn{sub 5}/Al/AlO{sub x}/Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn{sub 5} crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar-Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn{sub 5} has unconventional pairing symmetry.

  10. Fabrication and characterization of InAlN/GaN-based double-channel high electron mobility transistors for electronic applications

    NASA Astrophysics Data System (ADS)

    Xue, JunShuai; Zhang, JinCheng; Zhang, Kai; Zhao, Yi; Zhang, LinXia; Ma, XiaoHua; Li, XiaoGang; Meng, FanNa; Hao, Yue

    2012-06-01

    In our previous work [J. S. Xue et al., Appl. Phys. Lett. 100, 013507 (2012)], superior electron-transport properties are obtained in InAlN/GaN/InAlN/GaN double-channel (DC) heterostructures grown by pulsed metal organic chemical vapor deposition (PMOCVD). In this paper, we present a detailed fabrication and systematic characterization of high electron mobility transistors (HEMTs) fabricated on these heterostructures. The device exhibits distinct DC behavior concerning with both static-output and small-signal performance, demonstrating an improved maximum drain current density of 1059 mA/mm and an enhanced transconductance of 223 mS/mm. Such enhancement of device performance is attributed to the achieved low Ohmic contact resistance as low as 0.33 ± 0.05 Ω.mm. Moreover, very low gate diode reverse leakage current is observed due to the high quality of InAlN barrier layer deposited by PMOCVD. A current gain frequency of 10 GHz and a maximum oscillation frequency 21 GHz are also observed, which are comparable to the state-of-the-art AlGaN/GaN-based DC HEMT found in the literature. The results demonstrate the great potential of PMOCVD for application in InAlN-related device's epitaxy.

  11. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brückmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  12. Edge states and local electronic structure around an adsorbed impurity in a topological superconductor

    NASA Astrophysics Data System (ADS)

    Tai, Yuan-Yen; Choi, Hongchul; Ahmed, Towfiq; Ting, C. S.; Zhu, Jian-Xin

    2015-11-01

    Recently, topological superconducting states have attracted much interest. In this paper, we consider a topological superconductor with Z2 topological mirror order [Y.-Y. Tai et al., Phys. Rev. B 91, 041111(R) (2015), 10.1103/PhysRevB.91.041111] and s±-wave superconducting pairing symmetry, within a two-orbital model originally designed for iron-based superconductivity [Y.-Y. Tai et al., Europhys. Lett. 103, 67001 (2013), 10.1209/0295-5075/103/67001]. We predict the existence of gapless edge states. We also study the local electronic structure around an adsorbed interstitial magnetic impurity in the system, and find the existence of low-energy in-gap bound states even with a weak spin polarization on the impurity. We also discuss the relevance of our results to a recent scanning tunneling microscopy experiment on a Fe(Te,Se) compound with an adsorbed Fe impurity [J.-X. Yin et al., Nat. Phys. 11, 543 (2015), 10.1038/nphys3371], for which our density functional calculations show the Fe impurity is spin polarized.

  13. Self-organization in P_xGe_xSe_1-2x glasses^*

    NASA Astrophysics Data System (ADS)

    Chakravarty, Swapnajit; Georgiev, Daniel; Boolchand, Punit; Micoulaut, Matthieu

    2003-03-01

    Bulk glasses in the titled ternary, in the 0 < x < 0.26 composition range, are examined in MDSC and Raman scattering measurements. Both fresh and aged samples were studied. Bimodal endotherms are observed but only the high^T endotherm displays a reversing heat flow signal that represents a glass transition. The pre^_Tg endotherm is observed in quenched samples only, and represents an activation energy [1] associated with P4 units (Se^_P(Se_1/2)_3) converting to P3 (P(Se_1/2)_3) ones. T_g(x) accessed from the reversing heat flow are found to increase with x as a power^_law, displaying a cusp near x = 0.04. The non^_reversing enthalpy is found to display a global minimum in the 0.08 < x < 0.145 range identified with the self^_organized phase. Raman scattering reveals the isostatically rigid units ( P3 , P_4, CS and ES Ge(Se_1/2)_4) comprising building blocks of the self^_organized phase. These results are parallel to those encountered in the As^_Ge^_Se ternary [2,3]. ^*Supported by NSF grant DMR ^_01^_01808 1. D.G. Georgiev et al Phys. Rev. B 64,134204(2001) 2.Y. Wang et al Europhys. Lett. 52, 633 (2000) 3. T.Qu et al. companion abstract

  14. Reply to Gopalswamy et al.

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Richardson, I. G.

    2003-01-01

    The comment of Gopalswamy et al. (thereafter GMY) relates to a letter discussing coronal mass ejections (CMEs), interplanetary ejecta and geomagnetic storms. GMY contend that Cane et al. incorrectly identified ejecta (interplanetary CMEs) and hypothesize that this is because Cane et al. fail to understand how to separate ejecta from "shock sheaths" when interpreting solar wind and energetic particle data sets. They (GMY) are wrong be cause the relevant section of the paper was concerned with the propagation time to 1 AU of any potentially geoeffective structures caused by CMEs, i.e. upstream compression regions with or without shocks, or ejecta. In other words, the travel times used by Cane et al. were purposefully and deliberately distinct from ejecta travel times (except for those slow ejecta, approx. 30% of their events, which generated no upstream features), and no error in identification was involved. The confusion of GMY stems from the description did not characterize the observations sufficiently clearly.

  15. In memory of Al Cameron

    NASA Astrophysics Data System (ADS)

    Cowan, John; Truran, James W.

    Al Cameron, who died recently (October 3, 2005) at 80, was one of the giants in astrophysics. His insights were profound and his interests were wide-ranging. Originally trained as a nuclear physicist, he made major contributions in a number of fields, including nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, and the origin of the Solar System and the Moon. In 1957, Cameron and, independently, Burbidge, Burbidge, Fowler and Hoyle, wrote seminal papers on nuclear astrophysics. Most of our current ideas concerning ele- ment formation in stars have followed from those two pioneering and historical works. Al also made many contributions in the field of Solar System physics. Particularly noteworthy in this regard was Cameron's work on the formation of the Moon. Al was also a good friend and mentor of young people. Al Cameron will be missed by many in the community both for his scientific contributions and for his friendship.

  16. Al-Co-Fe (030)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-Co-Fe (030)' with the content:

  17. Al-La-Nb (068)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-La-Nb (068)' with the content:

  18. Al-Cu-Zr (050)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-Cu-Zr (050)' with the content:

  19. Al-La-Ni (069)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-La-Ni (069)' with the content:

  20. Al-Au-La (010)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-Au-La (010)' with the content:

  1. Al-Ce-V (029)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 1 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'Al-Ce-V (029)' with the content:

  2. Dissipative Particle Dynamics at Isoenergetic Conditions Using Shardlow-Like Splitting Algorithms

    DTIC Science & Technology

    2013-09-01

    Avalos and Mackie (3) and later independently by Español (4). The DPD-E method includes an additional equation-of-motion that provides a dynamic... Español (4). To conserve energy in a DPD simulation, an additional variable is introduced that characterizes the internal state of the particles. An...Dissipative Particle Dynamics With Energy Conservation. Europhys. Lett. 1997, 40, 141. 4. Español , P. Dissipative Particle Dynamics With Energy Conservation

  3. Super-Penrose process due to collisions inside ergosphere

    NASA Astrophysics Data System (ADS)

    Zaslavskii, O. B.

    If two particles collide inside the ergosphere, the energy in the center of mass frame can be made unbound provided at least one of particles has a large negative angular momentum [A. A. Grib and Yu. V. Pavlov, Europhys. Lett. 101 (2013) 20004]. We show that the same condition can give rise to unbounded Killing energy of debris at infinity, i.e. super-Penrose process. Proximity of the point of collision to the black hole horizon is not required.

  4. Growth and characterization of (In,Ga,Mn)As and (In,Al,Mn)As epilayers and heterostructures

    NASA Astrophysics Data System (ADS)

    Maksimov, O.; Sheu, B. L.; Schiffer, P.; Samarth, N.

    2004-03-01

    Lattice-matched III-Mn-V semiconductors on InP (001) substrates provide an attractive route toward the design of more magnetically concentrated ferromagnetic semiconductor alloys [1]. Here, we report the low temperature molecular beam epitaxy of (In_0.5Ga_0.5)_1-xMn_xAs and (In_0.5Al_0.5)_1-xMn_xAs epilayers, heterostructures and superlattices. Electron and x-ray diffraction studies show that the samples have structural quality similar to that of the more extensively studied (In,Mn)As and (Ga,Mn)As ferromagnetic semiconductors. Electron probe microanalysis measurements indicate that up to ˜ 11 % of Mn can be incorporated in the alloys. Magnetization measurements with a superconducting quantum interference device show that (In_0.5Ga_0.5)_0.89Mn_0.11As and (In_0.5Al_0.5)_0.89Mn_0.11As epilayers have a Curie temperature (T_C) ranging up to 95 K and 25 K, respectively. The consistently lower values of TC in (In_0.5Al_0.5)_1-xMn_xAs compared to (In_0.5Ga_0.5)_1-xMn_xAs are attributed to a reduced hole density caused by an enhanced acceptor activation energy. Work supported by grants from DARPA, ONR and NSF. 1. S. Ohya, H. Kobayashi, M. Tanaka, Appl. Phys. Lett. 83, 2175 (2003).

  5. Dynamical spin injection into a two-dimensional electron gas in an AlGaAs/GaAs structure

    NASA Astrophysics Data System (ADS)

    Ohtomo, Kenro; Ando, Yuichiro; Shinjo, Teruya; Uemura, Tetsuya; Shiraishi, Masashi

    A two-dimensional electron system in a GaAs-based heterostructure is the attractive platform for spintronics since it has high mobility and spin-orbit interaction can be modulated by the gate voltage1. Thus, it is a possible platform to realize electric gate-controlled spin transistor2. However, room-temperature spin transport through GaAs-based heterostructure has yet to be shown. We report first spin transport through the quantum well at GaAs/AlGaAs interface at room temperature. We used spin pumping under ferromagnetic resonance to inject spins from the Ni80Fe20 to the GaAs/AlGaAs quantum well. Generated spin current propagated through the 1 μm channel and was detected using spin-charge conversion inverse spin Hall effect in the Pt electrode. In agreement with spin pumping theory, polarity of the spin transport signal was reversed together with magnetization of the Ni80Fe20. This first demonstration of spin transport through a quantum well at a semiconductor heterostructure interface at room temperature opens a way to realize Datta-Das spin-based transistor.1 J. Nitta, et al., PRL 78, 1335 (1997). 2 S. Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990).

  6. Comparing the Thermodynamic Behaviour of Al(1)+ZrO2(s) to Al(1)+Al2O3(s)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2004-01-01

    In an effort to better determine the thermodynamic properties of Al(g) and Al2O(g). the vapor in equilibrium with Al(l)+ZrO2(s) was compared to the vapor in equilibrium with Al(l)+Al2O3(s) over temperature range 1197-to-1509K. The comparison was made directly by Knudsen effusion-cell mass spectrometry with an instrument configured for a multiple effusion-cell vapor source (multi-cell KEMS). Second law enthalpies of vaporization of Al(g) and Al2O(g) together with activity measurements show that Al(l)+ZrO2(s) is thermodynamically equivalent to Al(l)+Al2O3(s), indicating Al(l) remained pure and Al2O3(s) was present in the ZrO2-cell. Subsequent observation of the Al(l)/ZrO2 and vapor/ZrO2 interfaces revealed a thin Al2O3-layer had formed, separating the ZrO2-cell from Al(l) and Al(g)+Al2O(g), effectively transforming it into an Al2O3 effusion-cell. This behavior agrees with recent observations made for Beta-NiAl(Pt) alloys measured in ZrO2 effusion-cell.

  7. Ultra-hard amorphous AlMgB14 films RF sputtered onto curved substrates

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Putrolaynen, V. V.; Yuzvyuk, M. H.

    2017-03-01

    Recently, hard AlMgB14 (BAM) coatings were deposited for the first time by RF magnetron sputtering using a single stoichiometric ceramic target. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. They enabled fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young’s modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth in 2 µm thick film (Grishin et al 2014 JETP Lett. 100 680). The narrow range of sufficiently short target-to-substrate distance makes impossible to coat non flat specimens. To achieve ultimate BAM films’ characteristics onto curved surfaces we developed two-step sputtering process. The first thin layer is deposited as a template at low RF power that facilitates a layered Frank van der Merwe mode growth of smooth film occurs. The next layer is grown at high RF target sputtering power. The affinity of subsequent flow of sputtered atoms to already evenly condensed template fosters the development of smooth film surface. As an example, we made BAM coating onto hemispherical 5 mm in diameter ball made from a hard tool steel and used as a head of a special gauge. Very smooth (6.6 nm RMS surface roughness) and hard AlMgB14 films fabricated onto commercial ball-shaped items enhance hardness of tool steel specimens by a factor of four.

  8. Resonant-state-expansion Born approximation with a correct eigen-mode normalisation

    NASA Astrophysics Data System (ADS)

    Doost, M. B.

    2016-08-01

    The Born approximation (Born 1926 Z. Phys. 38 802) is a fundamental result in physics, it allows the calculation of weak scattering via the Fourier transform of the scattering potential. As was done by previous authors (Ge et al 2014 New J. Phys. 16 113048) the Born approximation is extended by including in the formula the resonant-states (RSs) of the scatterer. However in this study unlike previous studies the included eigen-modes are correctly normalised with dramatic positive consequences for the accuracy of the method. The normalisation of RSs used in the previous RS expansion Born approximation or resonant-state expansion (RSE) Born approximation made in Ge et al (2014 New J. Phys. 16 113048) has been shown to be numerically unstable in Muljarov et al (2014 arXiv:1409.6877) and by analytics here. The RSs of the system can be calculated using my recently discovered RSE perturbation theory for dispersive electrodynamic scatterers (Muljarov et al 2010 Europhys. Lett. 92 50010; Doost et al 2012 Phys. Rev. A 85 023835; Doost et al 2013 Phys. Rev. A 87 043827; Armitage et al 2014 Phys. Rev. A 89; Doost et al 2014 Phys. Rev. A 90 013834) and normalised correctly to appear in spectral Green's functions and hence the RSE Born approximation via the flux-volume normalisation which I recently rigorously derived in Armitage et al (2014 Phys. Rev. A 89), Doost et al (2014 Phys. Rev. A 90 013834), Doost (2016 Phys. Rev. A 93 023835). In the case of effectively one-dimensional systems I find a RSE Born approximation alternative to the scattering matrix method.

  9. Noisy covariance matrices and portfolio optimization II

    NASA Astrophysics Data System (ADS)

    Pafka, Szilárd; Kondor, Imre

    2003-03-01

    Recent studies inspired by results from random matrix theory (Galluccio et al.: Physica A 259 (1998) 449; Laloux et al.: Phys. Rev. Lett. 83 (1999) 1467; Risk 12 (3) (1999) 69; Plerou et al.: Phys. Rev. Lett. 83 (1999) 1471) found that covariance matrices determined from empirical financial time series appear to contain such a high amount of noise that their structure can essentially be regarded as random. This seems, however, to be in contradiction with the fundamental role played by covariance matrices in finance, which constitute the pillars of modern investment theory and have also gained industry-wide applications in risk management. Our paper is an attempt to resolve this embarrassing paradox. The key observation is that the effect of noise strongly depends on the ratio r= n/ T, where n is the size of the portfolio and T the length of the available time series. On the basis of numerical experiments and analytic results for some toy portfolio models we show that for relatively large values of r (e.g. 0.6) noise does, indeed, have the pronounced effect suggested by Galluccio et al. (1998), Laloux et al. (1999) and Plerou et al. (1999) and illustrated later by Laloux et al. (Int. J. Theor. Appl. Finance 3 (2000) 391), Plerou et al. (Phys. Rev. E, e-print cond-mat/0108023) and Rosenow et al. (Europhys. Lett., e-print cond-mat/0111537) in a portfolio optimization context, while for smaller r (around 0.2 or below), the error due to noise drops to acceptable levels. Since the length of available time series is for obvious reasons limited in any practical application, any bound imposed on the noise-induced error translates into a bound on the size of the portfolio. In a related set of experiments we find that the effect of noise depends also on whether the problem arises in asset allocation or in a risk measurement context: if covariance matrices are used simply for measuring the risk of portfolios with a fixed composition rather than as inputs to optimization, the

  10. Origin of the Two-Dimensional Electron Gas at LaAlO3/SrTiO3 Interfaces: The Role of Oxygen Vacancies and Electronic Reconstruction

    NASA Astrophysics Data System (ADS)

    Liu, Z. Q.; Li, C. J.; Lü, W. M.; Huang, X. H.; Huang, Z.; Zeng, S. W.; Qiu, X. P.; Huang, L. S.; Annadi, A.; Chen, J. S.; Coey, J. M. D.; Venkatesan, T.; Ariando

    2013-04-01

    The relative importance of atomic defects and electron transfer in explaining conductivity at the crystalline LaAlO3/SrTiO3 interface has been a topic of debate. Metallic interfaces with similar electronic properties produced by amorphous oxide overlayers on SrTiO3 [Y. Chen , Nano Lett. 11, 3774 (2011)NALEFD1530-698410.1021/nl201821j; S. W. Lee , Nano Lett. 12, 4775 (2012)NALEFD1530-698410.1021/nl302214x] have called in question the original polarization catastrophe model [N. Nakagawa , Nature Mater. 5, 204 (2006)NMAACR1476-112210.1038/nmat1569]. We resolve the issue by a comprehensive comparison of (100)-oriented SrTiO3 substrates with crystalline and amorphous overlayers of LaAlO3 of different thicknesses prepared under different oxygen pressures. For both types of overlayers, there is a critical thickness for the appearance of conductivity, but its value is always 4 unit cells (around 1.6 nm) for the oxygen-annealed crystalline case, whereas in the amorphous case, the critical thickness could be varied in the range 0.5 to 6 nm according to the deposition conditions. Subsequent ion milling of the overlayer restores the insulating state for the oxygen-annealed crystalline heterostructures but not for the amorphous ones. Oxygen post-annealing removes the oxygen vacancies, and the interfaces become insulating in the amorphous case. However, the interfaces with a crystalline overlayer remain conducting with reduced carrier density. These results demonstrate that oxygen vacancies are the dominant source of mobile carriers when the LaAlO3 overlayer is amorphous, while both oxygen vacancies and polarization catastrophe contribute to the interface conductivity in unannealed crystalline LaAlO3/SrTiO3 heterostructures, and the polarization catastrophe alone accounts for the conductivity in oxygen-annealed crystalline LaAlO3/SrTiO3 heterostructures. Furthermore, we find that the crystallinity of the LaAlO3 layer is crucial for the polarization catastrophe mechanism in the

  11. Modeling of the ALS linac

    SciTech Connect

    Kim, C.H.

    1996-08-01

    The ALS injector linac is used for the Beam Test Facility (BTF) and the Damping Experiments when it is available in between the ALS filings. These experiments usually require higher quality beams and a better characterization than is normally required for ALS operations. This paper focuses on the beam emittance, energy tilt, and especially the longitudinal variation of the beam parameters. For instance, the authors want to avoid longitudinal variations at the low beta section of the BTF. On the other hand, a large energy tilt is required for post-acceleration compression of the bunch using an alpha magnet. The PARMELA code was modified to calculate and display longitudinal variations of the emittance ellipse. Using the Microsoft Development Studio under Windows NT environment the code can handle a much larger number of particles than was previously possible.

  12. Superconductivity in Al/Al2O3 interface

    NASA Astrophysics Data System (ADS)

    Palnichenko, A. V.; Vyaselev, O. M.; Mazilkin, A. A.; Khasanov, S. S.

    2016-06-01

    Metastable superconductivity at Tc ≈ 65 K has been observed in Al foil subjected to special oxidation process, according to the ac magnetic susceptibility and electrical resistance measurements. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed during the oxidation process between metallic aluminum and its oxide.

  13. Baumard et al.'s moral markets lack market dynamics.

    PubMed

    Fessler, Daniel M T; Holbrook, Colin

    2013-02-01

    Market models are indeed indispensable to understanding the evolution of cooperation and its emotional substrates. Unfortunately, Baumard et al. eschew market thinking in stressing the supposed invariance of moral/cooperative behavior across circumstances. To the contrary, humans display contingent morality/cooperation, and these shifts are best accounted for by market models of partner choice for mutually beneficial collaboration.

  14. FTD and ALS: genetic ties that bind.

    PubMed

    Orr, Harry T

    2011-10-20

    Curiously, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), seemingly disparate neurodegenerative disorders, can be inherited together. Two groups (DeJesus-Hernandez et al. and Renton et al.) show that the long sought after ALS/FTD mutation on chromosomal region 9p is a hexanucleotide expansion in C90RF72. These studies, plus a study on X-linked ALS/FTD, provide molecular starting points for identifying pathways that link ALS and FTD pathogenesis.

  15. ALS - A unique design approach

    NASA Astrophysics Data System (ADS)

    Chamberlain, Roger A.

    1990-09-01

    An advanced launch system (ALS), which is intended to be flexible and to deliver a wide range of payloads at a reduced cost, is discussed. The ALS concept also features total quality management, modular subsystems, standardized interfaces, standardized missions, and off-line payload encapsulation. The technological improvements include manufacturing of dry structures, use of composite materials, adaptive guidance and control systems, and laser-initiated radar systems. The operational improvements range from paperless management, to rocket engine leak detection devices and automated ground operations.

  16. Simulating the microstructure of financial markets

    NASA Astrophysics Data System (ADS)

    Preis, Tobias

    2010-04-01

    In the beginning of exchange based trading, floor trading was the most widespread form of trading. In the course of the introduction and the progress in information technology, trading processes were adapted to the computational infrastructure at the international financial markets and electronic exchanges were created. These fully electronic exchanges are the starting point for recent agent-based models in econophysics, in which the explicit structure of electronic order books is integrated. The electronic order book structure builds the underlying framework of financial markets which is also contained in the recently introduced realistic Order Book Model [T. Preis et al., Europhys. Lett. 75, 510 (2006), T. Preis et al., Phys. Rev. E 76, 016108 (2007)]. This model provides the possibility to generate the stylized facts of financial markets with a very limited set of rules. This model is described and analyzed in detail. Using this model, it is possible to obtain short-term anti-correlated price time series. Furthermore, simple profitability aspects of the market participants can be reproduced. A nontrivial Hurst exponent can be obtained based on the introduction of a market trend, which leads to an anti-persistent scaling behavior of price changes on short time scales, a persistent scaling behavior on medium time scales, and a diffusive regime on long time scales. A coupling of the order placement depth to the prevailing market trend, which is identified to be a key variable in the Order Book Model, is able to reproduce fat-tailed price change distributions.

  17. Correlation effects and phonon modes softening with doping in Ba₁-xKxBiO₃.

    PubMed

    Korotin, Dm M; Novoselov, D; Anisimov, V I

    2014-05-14

    The monoclinic crystal structure of the undoped BaBiO₃ can be described as a cubic perovskite which is distorted by the frozen breathing and tilting phonon modes of the BiO₆ octahedra. The phonon mode softening is experimentally observed (Braden et al 1996 Europhys. Lett. 34 531) in Ba₁-xKxBiO₃ through potassium doping followed by a transition into an ideal cubic perovskite structure at x = 0.37, close to the emergence of superconductivity. In our previous paper (Korotin et al 2012 J. Phys.: Condens. Matter 24 415603) we demonstrated that it is necessary to take into account correlation effects using the DFT+U method in Wannier functions as a basis to obtain a good agreement between the calculated and experimental values of crystal structure distortion and the energy gap in BaBiO₃. In the present work, using the same method, we calculated the breathing mode phonon frequencies as a function of the potassium doping level in Ba₁-xKxBiO₃. The obtained frequencies are in good agreement with experimental values and the breathing mode softening with doping is reproduced, contrary to calculations made without consideration of correlation effects. We show that the cubic crystal structure becomes stable at x = 0.30 in agreement with the experimental transition to cubic perovskite at x = 0.37. The possible connections between the correlation effects, phonon mode softening and superconductivity in Ba₁-xKxBiO₃ are discussed.

  18. Algorithms and novel applications based on the isokinetic ensemble. I. Biophysical and path integral molecular dynamics

    NASA Astrophysics Data System (ADS)

    Minary, Peter; Martyna, Glenn J.; Tuckerman, Mark E.

    2003-02-01

    In this paper (Paper I) and a companion paper (Paper II), novel new algorithms and applications of the isokinetic ensemble as generated by Gauss' principle of least constraint, pioneered for use with molecular dynamics 20 years ago, are presented for biophysical, path integral, and Car-Parrinello based ab initio molecular dynamics. In Paper I, a new "extended system" version of the isokinetic equations of motion that overcomes the ergodicity problems inherent in the standard approach, is developed using a new theory of non-Hamiltonian phase space analysis [M. E. Tuckerman et al., Europhys. Lett. 45, 149 (1999); J. Chem. Phys. 115, 1678 (2001)]. Reversible multiple time step integrations schemes for the isokinetic methods, first presented by Zhang [J. Chem. Phys. 106, 6102 (1997)] are reviewed. Next, holonomic constraints are incorporated into the isokinetic methodology for use in fast efficient biomolecular simulation studies. Model and realistic examples are presented in order to evaluate, critically, the performance of the new isokinetic molecular dynamic schemes. Comparisons are made to the, now standard, canonical dynamics method, Nosé-Hoover chain dynamics [G. J. Martyna et al., J. Chem. Phys. 97, 2635 (1992)]. The new isokinetic techniques are found to yield more efficient sampling than the Nosé-Hoover chain method in both path integral molecular dynamics and biophysical molecular dynamics calculations. In Paper II, the use of isokinetic methods in Car-Parrinello based ab initio molecular dynamics calculations is presented.

  19. Dynamic Modeling of ALS Systems

    NASA Technical Reports Server (NTRS)

    Jones, Harry

    2002-01-01

    The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

  20. Microwave Transmission Measurements in Gated GaAs/AlGaAs Quantum Wells

    NASA Astrophysics Data System (ADS)

    Stone, Kristjan; Knez, Ivan; Du, Rui-Rui; Manfra, Michael; Pfeiffer, Loren; West, Ken

    2010-03-01

    Microwave transmission measurements across a 2D electron system have been previously demonstrated in quantum Hall effect and electronic solids regime [1]. We have developed a co-planar waveguide (CPW) system for experiments in microwave-induced resistance oscillations and zero resistance states. Microwaves from a tunable source (2 - 40 GHz) were fed into our system and coupled to a CPW meander line at 300mK to measure cyclotron resonance peaks from a carbon-doped (100) GaAs/AlxGa1-xAs quantum well 2D hole system. Our samples are Hall bars with mobility μ= 0.7-1 x10^6 cm^2/Vs and carrier density ranging from 2.02 - 2.26x10^11cm-2. Each sample has been gated with AuPd using a Si3N4 dielectric. A differential power measurement δP = Pout -Pout^gate is taken with the signal from the power sensor triggered from a modulated gate to remove the background microwave signal, yielding a cyclotron resonance peak from the transmission signal. We are able to fit our cyclotron transmission signal using the Drude model and determine the hole mass and the cyclotron scattering time. Experimental data as well as a brief discussion will be presented. The work at Rice was funded by NSF DMR-0706634. [1] L. W. Engel et al, Phys. Rev. Lett. 71, 2638 (1993).

  1. Relativistic general-order coupled-cluster method for high-precision calculations: Application to the Al{sup +} atomic clock

    SciTech Connect

    Kallay, Mihaly; Nataraj, H. S.; Sahoo, B. K.; Das, B. P.; Visscher, Lucas

    2011-03-15

    We report the implementation of a general-order relativistic coupled-cluster method for performing high-precision calculations of atomic and molecular properties. As a first application, the black-body radiation shift of the Al{sup +} clock has been estimated precisely. The computed shift relative to the frequency of the 3s{sup 2} {sup 1}S{sub 0}{sup e}{yields}3s3p {sup 3}P{sub 0}{sup o} clock transition given by (-3.66{+-}0.60)x10{sup -18} calls for an improvement over the recent measurement with a reported result of (-9{+-}3)x10{sup -18}[Phys. Rev. Lett. 104, 070802 (2010)].

  2. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

    NASA Astrophysics Data System (ADS)

    Zhang, Kun; Li, Huan-Huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-09-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices.

  3. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

    PubMed Central

    Zhang, Kun; Li, Huan-huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-tao; Tian, Yu-feng; Yan, Shi-shen; Lin, Zhao-jun; Kang, Shi-shou; Chen, Yan-xue; Liu, Guo-lei; Mei, Liang-mo

    2015-01-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices. PMID:26387967

  4. AlSb/InAs/AlSb quantum wells

    NASA Technical Reports Server (NTRS)

    Kroemer, Herbert

    1990-01-01

    Researchers studied the InAs/AlSb system recently, obtaining 12nm wide quantum wells with room temperature mobilities up to 28,000 cm(exp 2)/V center dot S and low-temperature mobilities up to 325,000 cm(exp 2)/V center dot S, both at high electron sheet concentrations in the 10(exp 12)/cm(exp 2) range (corresponding to volume concentrations in the 10(exp 18)/cm(exp 2) range). These wells were not intentionally doped; the combination of high carrier concentrations and high mobilities suggest that the electrons are due to not-intentional modulation doping by an unknown donor in the AlSb barriers, presumably a stoichiometric defect, like an antisite donor. Inasmuch as not intentionally doped bulk AlSb is semi-insulating, the donor must be a deep one, being ionized only by draining into the even deeper InAs quantum well. The excellent transport properties are confirmed by other observations, like excellent quantum Hall effect data, and the successful use of the quantum wells as superconductive weak links between Nb electrodes, with unprecendentedly high critical current densities. The system is promising for future field effect transistors (FETs), but many processing problems must first be solved. Although the researchers have achieved FETs, the results so far have not been competitive with GaAs FETs.

  5. Effect of interface geometry on electron tunnelling in Al/Al2O3/Al junctions

    NASA Astrophysics Data System (ADS)

    Koberidze, M.; Feshchenko, A. V.; Puska, M. J.; Nieminen, R. M.; Pekola, J. P.

    2016-04-01

    We investigate how different interface geometries of an Al/Al2O3 junction, a common component of modern tunnel devices, affect electron transport through the tunnel barrier. We study six distinct Al/Al2O3 interfaces which differ in stacking sequences of the metal and the oxide surface atoms and the oxide termination. To construct model potential barrier profiles for each examined geometry, we rely on first-principles density-functional theory (DFT) calculations for the barrier heights and the shapes of the interface regions as well as on experimental data for the barrier widths. We show that even tiny variations in the atomic arrangement at the interface cause significant changes in the tunnel barrier parameters and, consequently, in electron transport properties. Especially, we find that variations in the crucial barrier heights and widths can be as large as 2 eV and 5 Å, respectively. Finally, to gain information about the average properties of the measured junction, we fit the conductance calculated within the Wentzel-Kramers-Brillouin approximation to the experimental data and interpret the fit parameters with the help of the DFT results.

  6. Relativity and Al^+ Optical Clocks

    NASA Astrophysics Data System (ADS)

    Chou, Chin-Wen; Hume, David B.; Wineland, David J.; Rosenband, Till

    2010-03-01

    We have constructed an optical clock based on quantum logic spectroscopy of an Al+ ion that has a fractional frequency inaccuracy of 8.6x10-18. The frequency of the ^1S0<->^3P0 clock transition is compared to that of a previously constructed Al^+ optical clock with a statistical measurement uncertainty of 7.0x10-18. The two clocks exhibit a relative stability of 2.8x10-15&-1/2circ;, and a fractional frequency difference of -1.8x10-17, consistent with the accuracy limit of the older clock. By comparing the frequencies of the clocks, we have observed relativistic effects, such as time dilation due to velocities less than 10 m/s and the gravitational red shift from a 0.33 m height change of one of the clocks.

  7. Localized electron states and phase separation at the LaAlO3/SrTiO3 interface

    NASA Astrophysics Data System (ADS)

    Satpathy, S.; Shanavas, K. V.

    2012-02-01

    Even though the 2D electron gas at the polar interfaces of LAO/STO has been studied extensively, an explanation for the observed magnetic centers or the coexistence of magnetism and superconductivity is still lacking. Earlier density-functional calculations have indicated the presence of multi-bands and two types of electrons at the interface [1]. Here we propose that a combination of lattice disorder, octahedral rotations, and Jahn-Teller distortion can lead to some of these electrons to be localized near the interface and form lattice polarons. Evidence for this is presented from detailed density-functional calculations, which indicate that the energy gain associated with JT distortion and impurity or disorder induced local potentials can offset the kinetic energy cost of localization. Our model studies [2] also show the possible existence of a phase separation, thereby providing a natural explanation for the coexistence of magnetism and superconductivity [3].[4pt] [1] Z. S. Popovi'c, S. Satpathy and R. M. Martin Phys. Rev. Lett., 101, 256801 (2008)[0pt] [2] B. R. K. Nanda and S. Satpathy Phys. Rev B, 83, 195114 (2011)[0pt] [3] L. Li et. al. Nature Physics, 7, 762 (2011); J. A. Bert et. al. ibid, 767 (2011);

  8. Nanolabyrinthine ZrAlN thin films by self-organization of interwoven single-crystal cubic and hexagonal phases

    NASA Astrophysics Data System (ADS)

    Ghafoor, Naureen; Johnson, Lars J. S.; Klenov, Dmitri O.; Demeulemeester, Jelly; Desjardins, Patrick; Petrov, Ivan; Hultman, Lars; Odén, Magnus

    2013-08-01

    Self-organization on the nanometer scale is a trend in materials research. Thermodynamic driving forces may, for example, yield chessboard patterns in metal alloys [Y. Ni and A. G. Khachaturyan, Nature Mater. 8, 410-414 (2009)], 10.1038/nmat2431 or nitrides [P. H. Mayrhofer, A. Hörling, L. Karlsson, J. Sjölén, T. Larsson, and C. Mitterer, Appl. Phys. Lett. 83, 2049 (2003)], 10.1063/1.1608464 during spinodal decomposition. Here, we explore the ZrN-AlN system, which has one of the largest positive enthalpies of mixing among the transition metal aluminum nitrides [D. Holec, R. Rachbauer, L. Chen, L. Wang, D. Luefa, and P. H. Mayrhofer, Surf. Coat. Technol. 206, 1698-1704 (2011), 10.1016/j.surfcoat.2011.09.019; B. Alling, A. Karimi, and I. Abrikosov, Surf. Coat. Technol. 203, 883-886 (2008)], 10.1016/j.surfcoat.2008.08.027. Surprisingly, a highly regular superhard (36 GPa) two-dimensional nanolabyrinthine structure of two intergrown single crystal phases evolves during magnetron sputter thin film synthesis of Zr0.64Al0.36N/MgO(001). The self-organization is surface driven and the synergistic result of kinetic limitations, where the enthalpy reduction balances both investments in interfacial and elastic energies.

  9. Phase Breaking in InAs/AlGaSb Open Quantum Dot Structures

    NASA Astrophysics Data System (ADS)

    Maemoto, T.; Kitamura, Y.; Ueda, K.; Sasa, S.; Inoue, M.; Ishibashi, K.; Aoyagi, Y.

    2002-03-01

    We report on phase breaking times in InAs/AlGaAs open quantum dot structures in ballistic transport regimes. These results are compared with the results of InAs quantum wires and lateral surface superlattices [1]. The open dot structures with sub-micron scale have been fabricated by electron beam lithography and split-gate technique. Fluctuations of magnetoresistance have been observed at 4.2 K from low magnetic fields below 1 T, which were not seen in the conventional devices. The large-period fluctuations can be analyzed from the semi-classical scattering trajectory depending on the geometrical feature of the devices. In addition to these large-period conductance fluctuations, the short-period fluctuations have been also observed even at 4.2K. These fluctuations may result from the complex modes of the interference electron waves possibly characterized by highly characteristic wave function scarring [2]. From the analyses of correlation functions of these magneto-oscillations [3], the phase breaking times of the present InAs/AlGaSb open quantum dot structures were estimated to be 20-50 ps. [1] T. Maemoto, M. Ichiu, A. Ohya, S. Sasa, M. Inoue, K. Ishibashi, Y. Aoyagi, Physica B 272, 110 (1999). [2] R. Akis, D. K. Ferry, and J. P. Bird, Phys. Rev. Lett. 79, 123 (1997). [3] K. Ishibashi, J. P. Bird, D. K. Ferry, M. Lakrimi, A. D. Grassie, K. M. Hutchings, Y. Ochiai, T. Sugano and Y. Aoyagi, Jpn. J. Appl. Phys. 34, 6966 (1995).

  10. [Coagulation behavior of Al13 species].

    PubMed

    Hu, Cheng-zhi; Liu, Hui-juan; Qu, Jiu-hui

    2006-12-01

    Coagulation behavior of Al13 species was examined in synthetic water with high alkalinity and high humic acid concentration from viewpoint of the transformation of Al hydrolysis products during the coagulation process. The results indicated that coagulation efficiency of Al coagulants positively correlated with the content of Al13 in the coagulation process. Aluminum chloride (AlCl3) was more effective than polyaluminum chloride (PACI) in removing turbidity and dissolved organic matter in the synthetic water because AlCl3 could not only generate Al13 species but also function as pH control agent in the coagulation process. During coagulation process pH control can improve coagulation process through regulating Al speciation, and AlCl3 benefited most from pH control.

  11. Synthesis of AlN/Al Polycrystals along with Al Nanoparticles Using Thermal Plasma Route

    SciTech Connect

    Kanhe, Nilesh S.; Nawale, A. B.; Kulkarni, N. V.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

    2011-07-15

    This paper for the first time reports the (200) oriented growth of hexagonal Aluminum nitride crystals during synthesis of aluminum nanoparticles in dc transferred arc thermal plasma reactor by gas phase condensation in nitrogen plasma. The structural and morphological study of as synthesized AlN crystal and aluminium nanoparticles was done by using the x-ray diffraction method, scanning electron microscopy and transmission electron microscopy.

  12. Investigations of Al-Dalang and Al-Hawashat meteorites

    NASA Astrophysics Data System (ADS)

    Gismelseed, A. M.; Abdallah, S. B.; Al-Rawas, A. D.; Al-Mabsali, F. N.; Widatallah, H. M.; Elzain, M. E.; Yousif, A. A.; Ericsson, T.; Annersten, H.

    2016-12-01

    Mössbauer spectroscopy, X-ray diffraction (XRD) measurements, and electron microprobe analysis (EMPA) have been performed on two meteorites named Al-Dalang and Al-Hawashat after identifying their falling sites in the Western region of Sudan. These two meteorites are ordinary chondrites with similar mineralogy. XRD and EMPA show that the two specimens consist of primary olivine, ortho-pyroxene and later crystallising clino-pyroxene as reaction rims against plagioclase. Fe-metal phases are dominated by kamacite (≈6 wt.% Ni) and minor amounts of tetrataenite (≈52 wt.% Ni). Troilite (FeS) and alabandite (MnS) are optically observed as sulphide phases. The Mössbauer measurements at 295 and 78 K are in agreement with the above characterizations, showing at least two paramagnetic doublets which are assigned to olivine and pyroxene and magnetic sextets assigned to kamacite (hyperfine field ≈33.5 T) and troilite FeS (hyperfine field ≈31 T).

  13. Al-Al2O3-Pd junction hydrogen sensor

    NASA Astrophysics Data System (ADS)

    Okuyama, K.; Takinami, N.; Chiba, Y.; Ohshima, S.; Kambe, S.

    1994-07-01

    Al-Al2O3-Pd MIM (metal insulator metal) junctions fabricated on a glass substrate were tested as hydrogen sensors. The I-V (current versus voltage) characteristics of the junctions were measured at room temperature in a vacuum of 10-5 Torr and in H2 gas of 10-2-100 Torr. A significant increase in the current was observed upon introduction of H2 gas. This phenomenon is believed to occur due to the work function lowering of the hydrogen-absorbed Pd top electrode. The rise time was on the order of minutes, while the recovery time when hydrogen was purged was more than 20 h. However, when the junction was placed in an oxidizing ambient such as air, the recovery time was drastically reduced to the order of minutes, indicating that the device is operative as a hydrogen sensor in the atmospheric ambient. Hydrogen adsorption and desorption behavior of the Pd film was also investigated using a Pd coated quartz microbalance, and the results explained the current response of the Pd MIM junction to hydrogen in the presence of oxygen.

  14. Ab initio modeling of zincblende AlN layer in Al-AlN-TiN multilayers

    DOE PAGES

    Yadav, S. K.; Wang, J.; Liu, X. -Y.

    2016-06-13

    An unusual growth mechanism of metastable zincblende AlN thin film by diffusion of nitrogen atoms into Al lattice is established. Using first-principles density functional theory, we studied the possibility of thermodynamic stability of AlN as a zincblende phase due to epitaxial strains and interface effect, which fails to explain the formation of zincblende AlN. We then compared the formation energetics of rocksalt and zincblende AlN in fcc Al through direct diffusion of nitrogen atoms to Al octahedral and tetrahedral interstitials. Furthermore, the formation of a zincblende AlN thin film is determined to be a kinetically driven process, not a thermodynamicallymore » driven process.« less

  15. NiAl-base composite containing high volume fraction of AlN for advanced engines

    NASA Technical Reports Server (NTRS)

    Hebsur, Mohan (Inventor); Whittenbeger, John D. (Inventor); Lowell, Carl F. (Inventor)

    1994-01-01

    A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

  16. Internal-external stimulus competition in a system of interacting moving particles: Persuasion versus propaganda.

    PubMed

    Clementi, N C; Revelli, J A; Sibona, G J

    2015-07-01

    We propose a general nonlinear analytical framework to study the effect of an external stimulus in the internal state of a population of moving particles. This novel scheme allows us to study a broad range of excitation transport phenomena. In particular, considering social systems, it gives insight of the spatial dynamics influence in the competition between propaganda (mass media) and convincement. By extending the framework presented by Terranova et al. [Europhys. Lett. 105, 30007 (2014)], we now allow changes in individual's opinions due to a reflection induced by mass media. The equations of the model could be solved numerically, and, for some special cases, it is possible to derive analytical solutions for the steady states. We implement computational simulations for different social and dynamical systems to check the accuracy of our scheme and to study a broader variety of scenarios. In particular, we compare the numerical outcome with the analytical results for two possible real cases, finding a good agreement. From the results, we observe that mass media dominates the opinion state in slow dynamics communities; whereas, for higher agent active speeds, the rate of interactions increases and the opinion state is determined by a competition between propaganda and persuasion. This difference suggests that kinetics can not be neglected in the study of transport of any excitation over a particle system.

  17. Internal-external stimulus competition in a system of interacting moving particles: Persuasion versus propaganda

    NASA Astrophysics Data System (ADS)

    Clementi, N. C.; Revelli, J. A.; Sibona, G. J.

    2015-07-01

    We propose a general nonlinear analytical framework to study the effect of an external stimulus in the internal state of a population of moving particles. This novel scheme allows us to study a broad range of excitation transport phenomena. In particular, considering social systems, it gives insight of the spatial dynamics influence in the competition between propaganda (mass media) and convincement. By extending the framework presented by Terranova et al. [Europhys. Lett. 105, 30007 (2014), 10.1209/0295-5075/105/30007], we now allow changes in individual's opinions due to a reflection induced by mass media. The equations of the model could be solved numerically, and, for some special cases, it is possible to derive analytical solutions for the steady states. We implement computational simulations for different social and dynamical systems to check the accuracy of our scheme and to study a broader variety of scenarios. In particular, we compare the numerical outcome with the analytical results for two possible real cases, finding a good agreement. From the results, we observe that mass media dominates the opinion state in slow dynamics communities; whereas, for higher agent active speeds, the rate of interactions increases and the opinion state is determined by a competition between propaganda and persuasion. This difference suggests that kinetics can not be neglected in the study of transport of any excitation over a particle system.

  18. Survival of Near-Critical Branching Brownian Motion

    NASA Astrophysics Data System (ADS)

    Berestycki, Julien; Berestycki, Nathanaël; Schweinsberg, Jason

    2011-06-01

    Consider a system of particles performing branching Brownian motion with negative drift μ= sqrt{2 - \\varepsilon} and killed upon hitting zero. Initially there is one particle at x>0. Kesten (Stoch. Process. Appl. 7:9-47, 1978) showed that the process survives with positive probability if and only if ɛ>0. Here we are interested in the asymptotics as ɛ→0 of the survival probability Q μ ( x). It is proved that if L=π/sqrt{\\varepsilon} then for all x∈ℝ, lim ɛ→0 Q μ ( L+ x)= θ( x)∈(0,1) exists and is a traveling wave solution of the Fisher-KPP equation. Furthermore, we obtain sharp asymptotics of the survival probability when x< L and L- x→∞. The proofs rely on probabilistic methods developed by the authors in (Berestycki et al. in arXiv: 1001.2337, 2010). This completes earlier work by Harris, Harris and Kyprianou (Ann. Inst. Henri Poincaré Probab. Stat. 42:125-145, 2006) and confirms predictions made by Derrida and Simon (Europhys. Lett. 78:60006, 2007), which were obtained using nonrigorous PDE methods.

  19. Fluctuation of similarity to detect transitions between distinct dynamical regimes in short time series

    NASA Astrophysics Data System (ADS)

    Malik, Nishant; Marwan, Norbert; Zou, Yong; Mucha, Peter J.; Kurths, Jürgen

    2014-06-01

    A method to identify distinct dynamical regimes and transitions between those regimes in a short univariate time series was recently introduced [N. Malik et al., Europhys. Lett. 97, 40009 (2012), 10.1209/0295-5075/97/40009], employing the computation of fluctuations in a measure of nonlinear similarity based on local recurrence properties. In this work, we describe the details of the analytical relationships between this newly introduced measure and the well-known concepts of attractor dimensions and Lyapunov exponents. We show that the new measure has linear dependence on the effective dimension of the attractor and it measures the variations in the sum of the Lyapunov spectrum. To illustrate the practical usefulness of the method, we identify various types of dynamical transitions in different nonlinear models. We present testbed examples for the new method's robustness against noise and missing values in the time series. We also use this method to analyze time series of social dynamics, specifically an analysis of the US crime record time series from 1975 to 1993. Using this method, we find that dynamical complexity in robberies was influenced by the unemployment rate until the late 1980s. We have also observed a dynamical transition in homicide and robbery rates in the late 1980s and early 1990s, leading to increase in the dynamical complexity of these rates.

  20. Screening out the non-Arrhenius behaviour of nematic-isotropic transition by room temperature ionic liquid

    NASA Astrophysics Data System (ADS)

    Dan, K.; Datta, A.; Yoshida, Y.; Saito, G.; Yoshikawa, K.; Roy, M.

    2016-02-01

    Differential Scanning Calorimetry (DSC) and optical polarization microscopy of a mixture of the liquid crystalline material (N-(4-methoxybenzylidene)-4-butylaniline, MBBA) and a Fe-based room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrachloroferrate ([Emim]+ [FeCl4]-, EMIF) indicate a decrease in the nematic-isotropic (N-I) phase transition temperature (TNI) with an increase in EMIF concentration, explained by a proposed model of Coulomb "screening" of MBBA quadrupoles by the EMIF ions along with ionic "self screening." DSC studies of EMIF-MBBA and pure EMIF and comparison with pure MBBA results show that the major transitions in pure EMIF have Arrhenius behaviour, but more importantly the previously found convex Arrhenius behaviour of the pristine MBBA [K. Dan et al., Europhys. Lett. 108, 36007 (2014)] becomes Arrhenius in the mixture, indicating a conversion of the entropic N-I activation barrier to an enthalpic one. In presence of EMIF, a drastic decrease in the intensity of out-of-plane distortions of benzene rings in MBBA is found from Fourier transform infrared spectroscopy, consistent with significant reduction in the conformational states of MBBA. This suppression of large amplitude motion is again consistent with a Coulomb screening and gives a molecular basis for the entropic-to-enthalpic conversion of the N-I activation barrier.

  1. The universe on a table top: engineering quantum decay of a relativistic scalar field from a metastable vacuum

    NASA Astrophysics Data System (ADS)

    Fialko, O.; Opanchuk, B.; Sidorov, A. I.; Drummond, P. D.; Brand, J.

    2017-01-01

    The quantum decay of a relativistic scalar field from a metastable state (‘false vacuum decay’) is a fundamental idea in quantum field theory and cosmology. This occurs via local formation of bubbles of true vacuum with their subsequent rapid expansion. It can be considered as a relativistic analog of a first-order phase transition in condensed matter. Here we expand upon our recent proposal (Fialko O et al 2015 Europhys. Lett. 110 56001) for an experimental test of false vacuum decay using an ultra-cold spinor Bose gas. A false vacuum for the relative phase of two spin components, serving as the unstable scalar field, is generated by means of a modulated linear coupling of the spin components. We analyze the system theoretically using the functional integral approach and show that various microscopic degrees of freedom in the system, albeit leading to dissipation in the relative phase sector, will not hamper the observation of the false vacuum decay in the laboratory. This is well supported by numerical simulations demonstrating the spontaneous formation of true vacuum bubbles on millisecond time-scales in two-component 7Li or 41K bosonic condensates in one-dimensional traps of ∼ 100 μ {{m}} size.

  2. Numerical solution of the stationary multicomponent nonlinear Schrödinger equation with a constraint on the angular momentum

    NASA Astrophysics Data System (ADS)

    Sandin, Patrik; Ögren, Magnus; Gulliksson, Mârten

    2016-03-01

    We formulate a damped oscillating particle method to solve the stationary nonlinear Schrödinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011), 10.1209/0295-5075/95/30002], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.

  3. On the influence of environmental parameters on mixing and reconnection caused by the Kelvin-Helmholtz instability at the magnetopause

    NASA Astrophysics Data System (ADS)

    Leroy, M. H. J.; Keppens, R.

    2017-01-01

    The process feeding the development of a large boundary layer at the interface between the solar wind and the magnetosphere during northward interplanetary magnetic field is still not fully understood, though the Kelvin-Helmholtz instability (KHI) being the major actor is in good agreement with the observations so far. In this article, we study the different configurations than can occur in the KHI scenario in a three-dimensional Hall-MHD setting, where the double mid-latitude reconnection (DMLR) process exposed by Faganello et al. [Europhys. Lett. 100, 69001 (2012)] is triggered by the equatorial roll-ups. Their previous work is extended here with, in particular, a larger simulation box and the addition of a density contrast. The influence of various parameters on the growth rate of the KHI and thus the efficiency of the DMLR is assessed. In the scope of assessing the effect of the Hall term on the physical processes, the simulations are also performed in the MHD frame. These different configurations may have discernible signatures that can be identified by spacecraft diagnostics; therefore the data that would be recorded by spacecrafts during such an event are simulated.

  4. Magnetism of SmFeAsO1-xFx

    NASA Astrophysics Data System (ADS)

    Kamihara, Yoichi; Kobayashi, Yasuhiro; Kitao, Shinji; Yoda, Yoshitaka; Seto, Makoto; Hosono, Hideo; Jst Collaboration; Jst Collaboration

    2011-03-01

    Magnetic properties of superconducting SmFeAs O1 - x Fx are demonstrated by 57 Fe Mossbauer spectroscopy (MS) and 149 Sm Nuclear resonant forward scattering (NRFS). Polycrystalline SmFeAs O1 - x Fx samples were synthesized using two-step solid state reaction described elsewhere. [New J. Phys. 12, 033005 (2010).] Purity of samples was checked by X-ray diffraction patterns using Cu K-alpha radiation. Resistivity and magnetization measurements, as well as by 57 Fe MS and 149 Sm NRFS spectroscopy, at various temperatures were performed to define superconducting, magnetic ordering temperatures. [Phys. Rev. B 78, 184512 (2008) & J. Phys. Soc. Japan 77, 103706 (2008).] A magnetic phase diagram we have proposed is closer to that by Hess et al [Europhys. Lett. 87, 17005 (2009).]; that is long-range AF ordering of Fe (a static magnetism) does not persist in the superconducting regime. Such a relation between spin dynamics and SC is a common feature among LnFeAs O1 - x Fx (Ln = La, Ce, Pr, Nd, and Sm). Our results indicate that the relation between the static magnetism and Tc of LnFeAs O1 - x Fx shows similar topology to that of copper-based high-Tc superconductors. [Phys. Rev. B 42, 7981 (1990).] One (Y. K) of us was financially supported by the Keio Leading-edge Laboratory of Science and Technology (KLL).

  5. Accelerated fluctuation analysis by graphic cards and complex pattern formation in financial markets

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Virnau, Peter; Paul, Wolfgang; Schneider, Johannes J.

    2009-09-01

    The compute unified device architecture is an almost conventional programming approach for managing computations on a graphics processing unit (GPU) as a data-parallel computing device. With a maximum number of 240 cores in combination with a high memory bandwidth, a recent GPU offers resources for computational physics. We apply this technology to methods of fluctuation analysis, which includes determination of the scaling behavior of a stochastic process and the equilibrium autocorrelation function. Additionally, the recently introduced pattern formation conformity (Preis T et al 2008 Europhys. Lett. 82 68005), which quantifies pattern-based complex short-time correlations of a time series, is calculated on a GPU and analyzed in detail. Results are obtained up to 84 times faster than on a current central processing unit core. When we apply this method to high-frequency time series of the German BUND future, we find significant pattern-based correlations on short time scales. Furthermore, an anti-persistent behavior can be found on short time scales. Additionally, we compare the recent GPU generation, which provides a theoretical peak performance of up to roughly 1012 floating point operations per second with the previous one. .

  6. Ion Heating Anisotropy during Dynamo Activity in the MST RFP

    NASA Astrophysics Data System (ADS)

    den Hartog, D. J.; Chapman, J. T.; Craig, D.; Fiksel, G.; Fontana, P. W.

    1999-11-01

    MHD dynamo activity is large in the MST Reversed-Field Pinch during sawtooth crashes, and small otherwise. During a sawtooth crash, ion temperature increases rapidly to a level several times as high as the temperature between sawteeth, which itself can be larger than the electron temperature. Several theories have been developed to explain this ion heating, some indicating a possible asymmetry in perpendicular to parallel heating [C. G. Gimblett, Europhys. Lett. 11, 541 (1990); Z. Yoshida, Nucl. Fusion 31, 386 (1991); N. Mattor, P. W. Terry, and S. C. Prager, Comments Plasma Phys. Controlled Fusion 15, 65 (1992)]. In standard MST discharges, impurity ion temperature measured perpendicular to the magnetic field (T_⊥) is higher than impurity ion temperature parallel to the magnetic field (T_allel) during a sawtooth crash. Throughout the rest of the sawtooth cycle, T_⊥ <= T_allel. This is in contrast to results obtained on the EXTRAP-T2 RFP which showed T_⊥ < T_allel throughout the discharge [K. Sasaki et al., Plasma Phys. Control. Fusion 39, 333 (1997)

  7. Elastic interaction between "hard" or "soft" pointwise inclusions on biological membranes.

    PubMed

    Bartolo, D; Fournier, J-B

    2003-06-01

    We calculate the induced elastic interaction between pointwise membrane inclusions that locally interact up to quadratic order with the membrane curvature tensor. For isotropic inclusions, we recover the usual interaction proportional to the inverse fourth power of the separation, however with a prefactor showing a non-trivial dependence on the rigidity Gamma of the quadratic potential. In the large-Gamma limit, corresponding to "hard" inclusions, we recover the standard prefactor first obtained by Goulian et al. (Europhys. Lett. 22, 145 (1993)). In the small-Gamma limit, corresponding to "soft" inclusions, we recover the recent result of Marchenko and Misbah (Eur. Phys. J. E 8, 477 (2002)). This shows that the latter result bears no fundamental discrepancy with previous works, but simply corresponds to the limit of soft inclusions. We discuss how the same inclusion can be depicted as hard or soft according to the degree of coarse-graining of the pointwise description. Finally, we argue that conical transmembrane proteins should be fundamentally considered as hard inclusions.

  8. Robust-yet-fragile nature of interdependent networks

    NASA Astrophysics Data System (ADS)

    Tan, Fei; Xia, Yongxiang; Wei, Zhi

    2015-05-01

    Interdependent networks have been shown to be extremely vulnerable based on the percolation model. Parshani et al. [Europhys. Lett. 92, 68002 (2010), 10.1209/0295-5075/92/68002] further indicated that the more intersimilar networks are, the more robust they are to random failures. When traffic load is considered, how do the coupling patterns impact cascading failures in interdependent networks? This question has been largely unexplored until now. In this paper, we address this question by investigating the robustness of interdependent Erdös-Rényi random graphs and Barabási-Albert scale-free networks under either random failures or intentional attacks. It is found that interdependent Erdös-Rényi random graphs are robust yet fragile under either random failures or intentional attacks. Interdependent Barabási-Albert scale-free networks, however, are only robust yet fragile under random failures but fragile under intentional attacks. We further analyze the interdependent communication network and power grid and achieve similar results. These results advance our understanding of how interdependency shapes network robustness.

  9. Numerical solution of the stationary multicomponent nonlinear Schrödinger equation with a constraint on the angular momentum.

    PubMed

    Sandin, Patrik; Ögren, Magnus; Gulliksson, Mårten

    2016-03-01

    We formulate a damped oscillating particle method to solve the stationary nonlinear Schrödinger equation (NLSE). The ground-state solutions are found by a converging damped oscillating evolution equation that can be discretized with symplectic numerical techniques. The method is demonstrated for three different cases: for the single-component NLSE with an attractive self-interaction, for the single-component NLSE with a repulsive self-interaction and a constraint on the angular momentum, and for the two-component NLSE with a constraint on the total angular momentum. We reproduce the so-called yrast curve for the single-component case, described in [A. D. Jackson et al., Europhys. Lett. 95, 30002 (2011)], and produce for the first time an analogous curve for the two-component NLSE. The numerical results are compared with analytic solutions and competing numerical methods. Our method is well suited to handle a large class of equations and can easily be adapted to further constraints and components.

  10. Coarse-grained simulation of lipid vesicles with ``n-atic'' orientational order

    NASA Astrophysics Data System (ADS)

    Geng, Jun; Selinger, Jonathan; Selinger, Robin

    2012-02-01

    We perform coarse-grained simulation studies of fluid lipid vesicles with in-plane ``n-atic'' orientational order associated with the shape of lipid head group, to test the theoretical predictions of Park, Lubensky and MacKintosh [1] for resulting vesicle shape and defect structures. Our simulation model uses a single layer coarse-grained implicit-solvent approach proposed by Yuan et al [2], with addition of an extra vector degree of freedom representing in-plane orientational order. We carry out simulation studies for n=1 to 6, examining in each case the spatial distribution of defects and resulting deformation of the vesicle. An initially spherical vesicle (genus zero) with n-atic order has a ground state with 2n vortices of strength 1/n, as expected, but the observed equilibrium shapes are sometimes quite different from those predicted theoretically. For the n=1 case, we find that the vesicle may become trapped in a disordered, long-lived metastable state with extra +/- defects whose pair-annihilation is inhibited by local changes in membrane curvature, and thus may never reach its predicted ground state. [4pt] [1] J. Park, T. C. Lubensky, and F. C. MacKintosh, Europhys. Lett. 20, 279 (1992)[0pt] [2] H. Yuan, C. Huang, Ju Li, G. Lykotrafitis, and S. Zhang, Phys. Rev. E 82, 011905 (2010)

  11. Upper and lower critical decay exponents of Ising ferromagnets with long-range interaction.

    PubMed

    Horita, Toshiki; Suwa, Hidemaro; Todo, Synge

    2017-01-01

    We investigate the universality class of the finite-temperature phase transition of the two-dimensional Ising model with the algebraically decaying ferromagnetic long-range interaction, J_{ij}=|r[over ⃗]_{i}-r[over ⃗]_{j}|^{-(d+σ)}, where d (=2) is the dimension of the system and σ is the decay exponent, by means of the order-N cluster-algorithm Monte Carlo method. In particular, we focus on the upper and lower critical decay exponents, the boundaries between the mean-field-universality, intermediate, and short-range-universality regimes. At the critical decay exponents, it is found that the standard Binder ratio of magnetization at the critical temperature exhibits extremely slow convergence as a function of the system size. We propose more effective physical quantities, namely the combined Binder ratio and the self-combined Binder ratio, both of which cancel the leading finite-size corrections of the conventional Binder ratio. Utilizing these techniques, we clearly demonstrate that in two dimensions, the lower and upper critical decay exponents are σ=1 and 7/4, respectively, contrary to the recent Monte Carlo and renormalization-group studies [M. Picco, arXiv:1207.1018; T. Blanchard et al., Europhys. Lett. 101, 56003 (2013)EULEEJ0295-507510.1209/0295-5075/101/56003].

  12. Upper and lower critical decay exponents of Ising ferromagnets with long-range interaction

    NASA Astrophysics Data System (ADS)

    Horita, Toshiki; Suwa, Hidemaro; Todo, Synge

    2017-01-01

    We investigate the universality class of the finite-temperature phase transition of the two-dimensional Ising model with the algebraically decaying ferromagnetic long-range interaction, Ji j=|r⃗i-r⃗j| -(d +σ ) , where d (=2) is the dimension of the system and σ is the decay exponent, by means of the order-N cluster-algorithm Monte Carlo method. In particular, we focus on the upper and lower critical decay exponents, the boundaries between the mean-field-universality, intermediate, and short-range-universality regimes. At the critical decay exponents, it is found that the standard Binder ratio of magnetization at the critical temperature exhibits extremely slow convergence as a function of the system size. We propose more effective physical quantities, namely the combined Binder ratio and the self-combined Binder ratio, both of which cancel the leading finite-size corrections of the conventional Binder ratio. Utilizing these techniques, we clearly demonstrate that in two dimensions, the lower and upper critical decay exponents are σ =1 and 7/4, respectively, contrary to the recent Monte Carlo and renormalization-group studies [M. Picco, arXiv:1207.1018; T. Blanchard et al., Europhys. Lett. 101, 56003 (2013) 10.1209/0295-5075/101/56003].

  13. Fluctuation of similarity to detect transitions between distinct dynamical regimes in short time series.

    PubMed

    Malik, Nishant; Marwan, Norbert; Zou, Yong; Mucha, Peter J; Kurths, Jürgen

    2014-06-01

    A method to identify distinct dynamical regimes and transitions between those regimes in a short univariate time series was recently introduced [N. Malik et al., Europhys. Lett. 97, 40009 (2012)], employing the computation of fluctuations in a measure of nonlinear similarity based on local recurrence properties. In this work, we describe the details of the analytical relationships between this newly introduced measure and the well-known concepts of attractor dimensions and Lyapunov exponents. We show that the new measure has linear dependence on the effective dimension of the attractor and it measures the variations in the sum of the Lyapunov spectrum. To illustrate the practical usefulness of the method, we identify various types of dynamical transitions in different nonlinear models. We present testbed examples for the new method's robustness against noise and missing values in the time series. We also use this method to analyze time series of social dynamics, specifically an analysis of the US crime record time series from 1975 to 1993. Using this method, we find that dynamical complexity in robberies was influenced by the unemployment rate until the late 1980s. We have also observed a dynamical transition in homicide and robbery rates in the late 1980s and early 1990s, leading to increase in the dynamical complexity of these rates.

  14. Temperature-dependent neutron diffraction measurements from D2O hydrating single-supported lipid bilayers of DMPC

    NASA Astrophysics Data System (ADS)

    Buck, Z. N.; Torres, J.; Mazza, A.; Kaiser, H.; Taub, H.; Hansen, F. Y.; Miskowiec, A.; Tyagi, M.

    The freezing point depression of water associated with biological membranes, studied principally by NMR, has been of interest for decades. Here we have used neutron diffraction measurements at the University of Missouri Research Reactor (MURR) to investigate the freezing behavior of water associated with single-supported zwitterionic lipid bilayers composed of DMPC. Diffraction patterns obtained as a function of temperature reveal that water freezes abruptly into its hexagonal phase at 270 K with no evidence of amorphous ice. Following the initial crystallization of the membrane-associated water there is a region of continuous hexagonal crystal growth, which is believed to occur in the interfacial water closest to the membrane. The temperature-dependent intensity of the observed Bragg peaks have been compared with that of incoherently elastically-scattered neutrons collected on the High-Flux Backscattering Spectrometer at NIST from an identical sample hydrated with H2O [2]. We find excellent agreement between the two data sets, suggesting the absence of amorphous solid water and that all the water hydrating a DMPC membrane eventually freezes into the hexagonal crystalline phase. 2 M. Bai et al., Europhys. Lett. 98, 48006 (2012). Supported by NSF Grant Nos. DMR-0944772 and DGE-1069091.

  15. Fluctuation spectrum and size scaling of river flow and level

    NASA Astrophysics Data System (ADS)

    Dahlstedt, Kajsa; Jensen, Henrik Jeldtoft

    2005-03-01

    We describe the statistical properties of two large river systems: the Danube and the Mississippi. The properties of the two rivers are compared qualitatively to the general properties of a critical steady-state system. Specifically, we test the recent suggestion by Bramwell et al. (Europhys. Lett. 57 (2002) 310) that a universal probability density function (PDF) exists for the fluctuations in river level, namely the Bramwell-Holdsworth-Pinton (BHP) PDF. The statistical properties investigated in this paper are: the PDF of the river flow and river level; moment scaling with basin area; moment to moment scaling or relative scaling; and power spectral properties of the data. We find that the moments of the flow scale approximately with basin area and that the seasonally adjusted flows exhibit relative moment scaling. Compared to the Mississippi, the Danube shows large deviations from spatial scaling and the power spectra show considerable dependence on system size. This might be due to water use and regulations as well as inhomogeneities in the basin area. We also find that the PDF of level data in some, but not all, cases can be qualitatively approximated by the BHP PDF.

  16. Stretching DNA by a Constant Field

    NASA Astrophysics Data System (ADS)

    Hori, Yuko

    2005-03-01

    We consider the problem of stretching DNA by a constant field, such as an electric field or a hydrodynamic flow field. We obtain analytical expressions for the elongation of DNA under both weak and strong applied fields, in two and three dimensions. In the weak field limit we consider the effect of self-avoidance, which leads to a 9-fold enhancement of the average end-to-end distance over the result obtained when self-avoidance is ignored in two dimensions, and 3-fold increase in three dimensions. In the strong stretching regime we obtain the exact force-extension relation by mapping the problem to the Schrödinger equation for a simple harmonic oscillator in a time dependent potential. We use our theoretical results to comment on the experiment of Maier et al. ootnotetextB. Maier, U. Seifert, and J. O. Rä'dler, Europhys. Lett., 60, 622 (2002). on DNA adsorbed on a lipid bilayer in the presence of an in-plane electric field. In particular, we find that their estimate for the effective charge density of the DNA molecule, made on the basis of an approximate theory, requires significant corrections in light of our calculations. This work was supported by the NSF through grants DMR-9984471 and DMR-0403997. JK is a Cottrell Scholar of Research Corporation.

  17. Heterogeneous out-of-equilibrium nonlinear q -voter model with zealotry

    NASA Astrophysics Data System (ADS)

    Mellor, Andrew; Mobilia, Mauro; Zia, R. K. P.

    2017-01-01

    We study the dynamics of the out-of-equilibrium nonlinear q -voter model with two types of susceptible voters and zealots, introduced in Mellor et al. [Europhys. Lett. 113, 48001 (2016), 10.1209/0295-5075/113/48001]. In this model, each individual supports one of two parties and is either a susceptible voter of type q1 or q2, or is an inflexible zealot. At each time step, a qi-susceptible voter (i =1 ,2 ) consults a group of qi neighbors and adopts their opinion if all group members agree, while zealots are inflexible and never change their opinion. This model violates detailed balance whenever q1≠q2 and is characterized by two distinct regimes of low and high density of zealotry. Here, by combining analytical and numerical methods, we investigate the nonequilibrium stationary state of the system in terms of its probability distribution, nonvanishing currents, and unequal-time two-point correlation functions. We also study the switching time properties of the model by exploiting an approximate mapping onto the model of Mobilia [Phys. Rev. E 92, 012803 (2015), 10.1103/PhysRevE.92.012803] that satisfies the detailed balance, and we outline some properties of the model near criticality.

  18. Superconducting transition temperatures and coherence length in non-s-wave pairing materials correlated with spin-fluctuation mediated interaction

    NASA Astrophysics Data System (ADS)

    Angilella, G. G.; March, N. H.; Pucci, R.

    2002-03-01

    Following earlier work on electron or hole liquids flowing through assemblies with magnetic fluctuations, we have recently exposed a marked correlation of the superconducting temperature Tc, for non-s-wave pairing materials, with coherence length ξ and effective mass m*. The very recent study of Abanov et al. [Europhys. Lett. 54, 488 (2001)] and the prior investigation of Monthoux and Lonzarich [Phys. Rev. B 59, 14 598 (1999)] have each focused on the concept of a spin-fluctuation temperature Tsf, which again is intimately related to Tc. For the d-wave pairing via antiferromagnetic spin fluctuations in the cuprates, these studies are brought into close contact with our own work, and the result is that kBTsf~ħ2/m*ξ2. This demonstrates that ξ is also determined by such antiferromagnetic spin-fluctuation mediated pair interaction. The coherence length in units of the lattice spacing is then essentially given in the cuprates as the square root of the ratio of two characteristic energies, namely, the kinetic energy of localization of a charge carrier of mass m* in a specified magnetic correlation length to the hopping energy. The quasi-two-dimensional ruthenate Sr2RuO4, with Tc~1.3 K, has p-wave spin-triplet pairing and so is also briefly discussed here.

  19. Automatic Network Fingerprinting through Single-Node Motifs

    PubMed Central

    Echtermeyer, Christoph; da Fontoura Costa, Luciano; Rodrigues, Francisco A.; Kaiser, Marcus

    2011-01-01

    Complex networks have been characterised by their specific connectivity patterns (network motifs), but their building blocks can also be identified and described by node-motifs—a combination of local network features. One technique to identify single node-motifs has been presented by Costa et al. (L. D. F. Costa, F. A. Rodrigues, C. C. Hilgetag, and M. Kaiser, Europhys. Lett., 87, 1, 2009). Here, we first suggest improvements to the method including how its parameters can be determined automatically. Such automatic routines make high-throughput studies of many networks feasible. Second, the new routines are validated in different network-series. Third, we provide an example of how the method can be used to analyse network time-series. In conclusion, we provide a robust method for systematically discovering and classifying characteristic nodes of a network. In contrast to classical motif analysis, our approach can identify individual components (here: nodes) that are specific to a network. Such special nodes, as hubs before, might be found to play critical roles in real-world networks. PMID:21297963

  20. Benefits for Military Veterans with ALS

    MedlinePlus

    ... Advocate Get Involved Donate Military Veterans Resources for Military Veterans, Families & Survivors The ALS Association is working everyday to ... and Caregivers Newly Diagnosed Clinical Trials Familial ALS Military Veterans For Caregivers Resources Read stories ... Site ...

  1. Cenomanian-Turonian biostratigraphy of the Jardas Al Abid area, Al Jabal Al Akhdar, northeast Libya

    NASA Astrophysics Data System (ADS)

    El Qot, Gamal M.; Abdulsamad, Esam O.

    2016-09-01

    The Upper Cenomanian-Turonian succession exposed at Jardas al'Abid area consists mainly of carbonates with siliciclastic intercalations. This succession is subdivided lithostratigraphically into: Qasr al'Abid (Late Cenomanian) and Al Baniyah (Late Cenomanian-Coniacian) formations. This sequence is relatively rich in macrofossil assemblages especially bivalves, gastropods, and echinoids with rare ammonites. Based on the first occurrence (FO) and last occurrence (LO) of some index species of these macrofossil groups, an integrated biostratigraphic framework has been constructed. The studied Cenomanian-Turonian sequence is subdivided biostratigraphically into three ammonite biozones; Pseudaspidoceras pseudonodosoides Total Range Zone, Choffaticeras segne Total Range Zone, and Coilopoceras requienianum Total Range Zone. Based on the rest of macrofossil assemblages other than the ammonites, eight biozones were recognized; Mecaster batnensis Total Range Zone, Ceratostreon flabellatum-Neithea dutrugei Acme Zone, Costagyra olisiponensis Acme Zone, Pycnodonte (Phygraea) vesicularis vesiculosa Acme Zone, Mytiloides labiatus Total Range Zone = Mecaster turonensis Acme Zone, Rachiosoma rectilineatum-Curvostrea rouvillei-Tylostoma (T.) globosum Assemblage Zone, Radiolites sp.-Apricardia? matheroni Total Range Zone, and Nerinea requieniana Total Range Zone. Most of the proposed biozones are recorded for the first time from Libya. The integration among these biozones as well as local and inter-regional correlation of the biozones have been discussed. The stage boundaries of the studied stratigraphic intervals are discussed, where the Cenomanian/Turonian boundary is delineated at the last occurrence (LO) of Pseudaspidoceras pseudonodosoides (Choffat), while the Turonian/Coniacian boundary is delineated arbitrary being agree with the LO of the Turonian fauna.

  2. Effects of the Al content on pore structures of porous TieAl alloys

    SciTech Connect

    Jaing, Y; He, Y H; Xu, N P; Zou, J; Huang, B; Lui, C T

    2008-01-01

    Porous TieAl alloys with different nominal compositions were fabricated through a reactive synthesis of Ti and Al elemental powders. It has been found that the pore parameters vary with the Al contents, indicating that the nature of the pores can be manipulated through changing the Al contents. In addition, detailed structural characterizations showed that the fabricated porous TieAl alloys can have three crystalline phases (i.e., a2-Ti3Al, g-TiAl, and TiAl3) when using different compositions. The fundamental reasons behind these phenomena have been explored.

  3. Photoelectrical, photophysical and photocatalytic properties of Al based MOFs: MIL-53(Al) and MIL-53-NH2(Al)

    NASA Astrophysics Data System (ADS)

    An, Yang; Li, Huiliang; Liu, Yuanyuan; Huang, Baibiao; Sun, Qilong; Dai, Ying; Qin, Xiaoyan; Zhang, Xiaoyang

    2016-01-01

    Two Al based MOFs (MIL-53(Al) and MIL-53-NH2 (Al)) were synthesized, and their photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water were investigated. Different from the ligand to metal charge transfer process previously reported, we proposes a new photocatalytic mechanism based on electron tunneling according to the results of theoretical calculation, steady state and time resolved fluorescence spectra. The organic linkers absorb photons, giving rise to electrons and holes. Then, the photogenerated electrons tunnel through the AlO6-octahedra, which not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs.

  4. Framework Al zoning in zeolite ECR-1.

    PubMed

    Shin, Jiho; Ahn, Nak Ho; Cho, Sung June; Ren, Limin; Xiao, Feng-Shou; Hong, Suk Bong

    2014-02-25

    Rietveld analyses of the synchrotron X-ray diffraction data for various cation forms of zeolite ECR-1 have demonstrated framework Al zoning, which parallels the alternation of Al-rich maz and Al-poor mor layers. This can be further supported by notable differences in the average bond valence of its 10 crystallographically distinct tetrahedral sites.

  5. Opportunity's 'Rub al Khali' Panorama

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Opportunity's 'Rub al Khali' Panorama (QTVR)

    This panoramic image, dubbed 'Rub al Khali,' was acquired by NASA's Mars Exploration Rover Opportunity on the plains of Meridiani during the period from the rover's 456th to 464th sols on Mars (May 6 to May 14, 2005). Opportunity was about 2 kilometers (1.2 miles) south of 'Endurance Crater' at a place known informally as 'Purgatory Dune.'

    The rover was stuck in the dune's deep fine sand for more than a month. 'Rub al Khali' (Arabic translation: 'the empty quarter') was chosen as the name for this panorama because it is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.

    The view spans 360 degrees. It consists of images obtained in 97 individual pointings of the panoramic camera. The camera took images with five camera filters at each pointing. This 22,780-by-6,000-pixel mosaic is an approximately true-color rendering generated using the images acquired through filters admitting light wavelengths of 750, 530, and 480 nanometers.

    Lighting varied during the nine sols it took to acquire this panorama, resulting in some small image seams within the mosaic. These seams have been smoothed in sky parts of the mosaic to better simulate the vista that a person would see if able to view it all at the same time on Mars.

    Opportunity's tracks leading back to the north (center of the panorama) are a reminder of the rover's long trek from Endurance Crater. The deep ruts dug by Opportunity's wheels as it became stuck in the sand appear in the foreground. The crest and trough of the last ripple the rover crossed before getting stuck is visible in the center. These wind-formed sand features are only about 10 to 15 centimeters (4 to 6 inches) tall. The crest of the actual ripple where the rover got stuck can be seen just to the right of center. The tracks and a few other places on and near ripple crests can

  6. Transport and capture properties of Auger-generated high-energy carriers in (AlInGa)N quantum well structures

    SciTech Connect

    Nirschl, A.; Binder, M.; Schmid, M.; Karow, M. M.; Pietzonka, I.; Lugauer, H.-J.; Zeisel, R.; Sabathil, M.; Galler, B.; Bougeard, D.

    2015-07-21

    Recent photoluminescence experiments presented by M. Binder et al. [Appl. Phys. Lett. 103, 071108 (2013)] demonstrated the visualization of high-energy carriers generated by Auger recombination in (AlInGa)N multi quantum wells. Two fundamental limitations were deduced which reduce the detection efficiency of Auger processes contributing to the reduction in internal quantum efficiency: the transfer probability of these hot electrons and holes in a detection well and the asymmetry in type of Auger recombination. We investigate the transport and capture properties of these high-energy carriers regarding polarization fields, the transfer distance to the generating well, and the number of detection wells. All three factors are shown to have a noticeable impact on the detection of these hot particles. Furthermore, the investigations support the finding that electron-electron-hole exceeds electron-hole-hole Auger recombination if the densities of both carrier types are similar. Overall, the results add to the evidence that Auger processes play an important role in the reduction of efficiency in (AlInGa)N based LEDs.

  7. Instandhaltungsmanagement als Gestaltungsfeld Ganzheitlicher Produktionssysteme

    NASA Astrophysics Data System (ADS)

    Dombrowski, Uwe; Schulze, Sven; Otano, Isabel Crespo

    Sich kontinuierlich verändernde Rahmenbedingungen, wie beispielsweise eine steigende Variantenvielfalt, verkürzte Produktlebenszyklen sowie Kundenforderungen nach höherer Qualität, kürzeren Lieferzeiten und geringeren Kosten, fordern von produzierenden Unternehmen eine stetige Anpassung der Prozesse, der Organisation und der Strukturen. Seit den 90er Jahren versuchen immer mehr deutsche Unternehmen diesen veränderten Anforderungen mit der Einführung eines Ganzheitlichen Produktionssystems (GPS) zu begegnen. Ganzheitliche Produktionssysteme sind dabei in ihren Grundlagen an das Toyota Produktionssystem angelehnt, vereinigen aber auch weitere Methoden zu einem unternehmensspezifischen Regelwerk. Im Rahmen des langfristigen Trends zu unternehmensindividuellen Produktionssystemen wird sowohl in der Industrie als auch in der Forschung intensiv über das Toyota Produktionssystem, Lean Production, Lean Management und Ganzheitliche Produktionssysteme diskutiert, werden Konzepte zu Implementierung und Betrieb erstellt und die Wirtschaftlichkeit untersucht.

  8. Systems Engineering Techniques for ALS Decision Making

    NASA Technical Reports Server (NTRS)

    Rodriquez, Luis F.; Drysdale, Alan E.; Jones, Harry; Levri, Julie A.

    2004-01-01

    The Advanced Life Support (ALS) Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Confounding the problem, the rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the rate at which new configurations are developed is slow, limiting the search space and potentially giving the perspective of a ALS technology, the ALS Metric may remain elusive. This paper is a sequel to a paper published in the proceedings of the 2003 ICES conference entitled, "Managing to the metric: an approach to optimizing life support costs." The conclusions of that paper state that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions. Certainly, these areas potentially offer large potential benefits to future ALS missions; however, the ALS Metric is not the only decision-making tool available to the community. To facilitate decision-making within the ALS community a combination of metrics should be utilized, such as the Equivalent System Mass (ESM)-based ALS metric, but also those available through techniques such as life cycle costing and faithful consideration of the sensitivity of the assumed models and data. Often a lack of data is cited as the reason why these techniques are not considered for utilization. An existing database development effort within the ALS community, known as OPIS, may provide the opportunity to collect the necessary information to enable the proposed systems analyses. A review of these additional analysis techniques is provided, focusing on the data necessary to enable these. The discussion is concluded by proposing how the data may be utilized by analysts in the future.

  9. Wear behavior of Al-Al{sub 3}Ti composite manufactured by a centrifugal method

    SciTech Connect

    Watanabe, Yoshimi; Yamanaka, Noboru; Fukui, Yasuyoshi

    1999-12-01

    The purpose of the present study was to develop a wear-resistant, light Al-Al{sub 3}Ti composite material. An Al-Al{sub 3}Ti composite specimen was machined from a thick-walled tube of Al-Al{sub 3}Ti functionally graded material (FGM) manufactured by the centrifugal method from a commercial ingot of Al-5 mass% Ti master alloy. The alloy was heated to a temperature where solid Al{sub 3}Ti particles resided in a liquid Al matrix, and then the centrifugal method was carried out. Al{sub 3}Ti particles in a commercial alloy ingot exist as platelets, and this shape was maintained through the casting. Three kinds of wear specimens were prepared, taking into account the morphology of the Al{sub 3}Ti particles in the thick-walled FGM tube; the Al{sub 3}Ti particles were arranged with their platelet planes nearly normal to the radial direction as a result of the applied centrifugal force. The wear resistance of the Al-Al{sub 3}Ti composite was significantly higher than that of pure Al. Wear-resistance anisotropy and dissolution of the Al{sub 3}Ti into the Al matrix at the near-surface region, around 100 {micro}m in depth, were also observed. The mechanism of the supersaturated-layer formation and the origin of the anisotropic wear resistance are discussed.

  10. Reflectance effects caused by refractive-index gradients of H2 samples loaded with 0.5-μm Al2O3 powder in diamond-anvil cells

    NASA Astrophysics Data System (ADS)

    Ruoff, Arthur L.; Greene, Raymond G.; Ghandehari, Kouros; Xia, Qing

    1993-05-01

    This paper shows that there is doubtful basis for the claim of metallization of hydrogen as a result of optical studies in the diamond-anvil cell to date. The presence of fine Al2O3 particles in the hydrogen precludes a simple hydrogen-diamond interface; the graded index must be included and is shown to account for the observed behavior in H. K. Mao et al. [Phys. Rev. Lett. 65, 484 (1990)] and M. Hanfland et al. [Phys. Rev. B 43, 8767 (1991)]. The small reflectivity found on the published experiment (having only a tiny fraction of the diamond covered with Al2O3) at 161 GPa and a mentioned result at 160 GPa (with no Al2O3), both at room temperature, is very likely due to an absorption peak of hydrogen in diamond at 0.38 eV broadened by the stresses in the diamond anvil. Therefore, it must be shown that refractive-index gradients and/or hydrogen in diamond are not responsible for the observed reflectance before other claims are made.

  11. Magnetism of Al-substituted magnetite reduced from Al-hematite

    NASA Astrophysics Data System (ADS)

    Jiang, Zhaoxia; Liu, Qingsong; Zhao, Xiang; Roberts, Andrew P.; Heslop, David; Barrón, Vidal; Torrent, José

    2016-06-01

    Aluminum-substituted magnetite (Al-magnetite) reduced from Al-substituted hematite or goethite (Al-hematite or Al-goethite) is an environmentally important constituent of magnetically enhanced soils. In order to characterize the magnetic properties of Al-magnetite, two series of Al-magnetite samples were synthesized through reduction of Al-hematite by a mixed gas (80% CO2 and 20% CO) at 395°C for 72 h in a quartz tube furnace. Al-magnetite samples inherited the morphology of their parent Al-hematite samples, but only those transformed from Al-hematite synthesized at low temperature possessed surficial micropores, which originated from the release of structural water during heating. Surface micropores could thus serve as a practical fingerprint of fire or other high-temperature mineralogical alteration processes in natural environments, e.g., shear friction in seismic zones. In addition, Al substitution greatly affects the magnetic properties of Al-magnetite. For example, coercivity (Bc) increases with increasing Al content and then decreases slightly, while the saturation magnetization (Ms), Curie temperature (Tc), and Verwey transition temperature (Tv) all decrease with increasing Al content due to crystal defect formation and dilution of magnetic ions caused by Al incorporation. Moreover, different trends in the correlation between Tc and Bc can be used to discriminate titanomagnetite from Al-magnetite, which is likely to be important in environmental and paleomagnetic studies, particularly in soil.

  12. Reply to Vance et al.

    SciTech Connect

    Woon-Chee Yee; Elliott, J.L; Kwon, J.M.; Goodfellow, P.

    1996-07-01

    In our report of a family with a motor and sensory polyneuropathy that was linked to chromosome 3q, we classified this neuropathy as a form of hereditary motor and sensory neuropathy II (HMSN II, also known as {open_quotes}CMT2{close_quotes}). Doubts have been raised by Vance et al. as to whether this neuropathy should be classified as hereditary sensory autonomic neuropathy I (HSAN I) instead of HMSN II. While it is reasonable to raise such doubts, we believe that the neuropathy is best designated as HMSN II for the reasons described below. The group of disorders described as HSAN are characterized by primary or predominant involvement of sensory and autonomic neurons that fail to develop or that undergo atrophy and degeneration. These disorders were extensively reviewed by Dyck and Ohta, who initially described them as the hereditary sensory neuropathies (HSN). It was Dyck who subsequently suggested that these disorders be designated HSAN rather than HSN, because of the presence of autonomic involvement. 8 refs.

  13. Primary damage in tungsten using the binary collision approximation, molecular dynamic simulations and the density functional theory

    NASA Astrophysics Data System (ADS)

    De Backer, A.; Sand, A.; Ortiz, C. J.; Domain, C.; Olsson, P.; Berthod, E.; Becquart, C. S.

    2016-02-01

    The damage produced by primary knock-on atoms (PKA) in W has been investigated from the threshold displacement energy (TDE) where it produces one self interstitial atom-vacancy pair to larger energies, up to 100 keV, where a large molten volume is formed. The TDE has been determined in different crystal directions using the Born-Oppenheimer density functional molecular dynamics (DFT-MD). A significant difference has been observed without and with the semi-core electrons. Classical MD has been used with two different empirical potentials characterized as ‘soft’ and ‘hard’ to obtain statistics on TDEs. Cascades of larger energy have been calculated, with these potentials, using a model that accounts for electronic losses (Sand et al 2013 Europhys. Lett. 103 46003). Two other sets of cascades have been produced using the binary collision approximation (BCA): a Monte Carlo BCA using SDTrimSP (Eckstein et al 2011 SDTrimSP: Version 5.00. Report IPP 12/8) (similar to SRIM www.srim.org) and MARLOWE (RSICC Home Page. (https://rsicc.ornl.gov/codes/psr/psr1/psr-137.html) (accessed May, 2014)). The comparison of these sets of cascades gave a recombination distance equal to 12 Å which is significantly larger from the one we reported in Hou et al (2010 J. Nucl. Mater. 403 89) because, here, we used bulk cascades rather than surface cascades which produce more defects (Stoller 2002 J. Nucl. Mater. 307 935, Nordlund et al 1999 Nature 398 49). Investigations on the defect clustering aspect showed that the difference between BCA and MD cascades is considerably reduced after the annealing of the cascade debris at 473 K using our Object Kinetic Monte Carlo model, LAKIMOCA (Domain et al 2004 J. Nucl. Mater. 335 121).

  14. Growth and Stress-induced Transformation of Zinc blende AlN Layers in Al-AlN-TiN Multilayers

    PubMed Central

    Li, Nan; Yadav, Satyesh K.; Wang, Jian; Liu, Xiang-Yang; Misra, Amit

    2015-01-01

    AlN nanolayers in sputter deposited {111}Al/AlN/TiN multilayers exhibit the metastable zinc-blende-structure (z-AlN). Based on density function theory calculations, the growth of the z-AlN is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}Al/AlN/TiN multilayers in a high-resolution transmission electron microscope revealed the z-AlN to wurzite AlN phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-AlN. PMID:26681109

  15. Growth and stress-induced transformation of zinc blende AlN layers in Al-AlN-TiN multilayers

    DOE PAGES

    Li, Nan; Yadav, Satyesh K.; Wang, Jian; ...

    2015-12-18

    We report that AlN nanolayers in sputter deposited {111}Al/AlN/TiN multilayers exhibit the metastable zinc-blende-structure (z-AlN). Based on density function theory calculations, the growth of the z-AlN is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}Al/AlN/TiN multilayers in a high-resolution transmission electron microscope revealed the z-AlN to wurzite AlN phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-AlN.

  16. Reactivity of aluminum cluster anions with ammonia: selective etching of Al11(-) and Al12(-).

    PubMed

    Grubisic, Andrej; Li, Xiang; Gantefoer, Gerd; Bowen, Kit H; Schnöckel, Hansgeorg; Tenorio, Francisco J; Martinez, Ana

    2009-11-14

    Reactivity of aluminum cluster anions toward ammonia was studied via mass spectrometry. Highly selective etching of Al(11)(-) and Al(12)(-) was observed at low concentrations of ammonia. However, at sufficiently high concentrations of ammonia, all other sizes of aluminum cluster anions, except for Al(13)(-), were also observed to deplete. The disappearance of Al(11)(-) and Al(12)(-) was accompanied by concurrent production of Al(11)NH(3)(-) and Al(12)NH(3)(-) species, respectively. Theoretical simulations of the photoelectron spectrum of Al(11)NH(3)(-) showed conclusively that its ammonia moiety is chemisorbed without dissociation, although in the case of Al(12)NH(3)(-), dissociation of the ammonia moiety could not be excluded. Moreover, since differences in calculated Al(n)(-) + NH(3) (n=9-12) reaction energies were not able to explain the observed selective etching of Al(11)(-) and Al(12)(-), we concluded that thermodynamics plays only a minor role in determining the observed reactivity pattern, and that kinetics is the more influential factor. In particular, the conversion from the physisorbed Al(n)(-)(NH(3)) to chemisorbed Al(n)NH(3)(-) species is proposed as the likely rate-limiting step.

  17. First-principles study of the Al(001)-Al3Nb(001) interfacial properties

    NASA Astrophysics Data System (ADS)

    Ding, Yanhong; Xu, Rui

    2017-03-01

    The adhesion, interfacial energy and bonding on fcc-Al(001)/D022-Al3Nb(001) interface were investigated using density functional calculations. Considering different terminations of Al3Nb(001) (Al+Nb-terminated and Al-terminated) and stacking sites (top-, bridge- and center-sites), six Al(001)/Al3Nb(001) models were calculated. For the models with same stacking site, Al+Nb-terminated model has larger work of adhesion (Wad) than the Al-terminated one. For the models with same termination, the work of adhesion increases, and the interface energy decreases as the order of center-sited, bridge-sited and top-sited. Al+Nb-terminated-center-sited and Al-terminated-center-sited models are more stable among six models. The interfacial bonding was discussed with analysis of valence electron density distribution and partial density of states (PDOS). The bonding is mainly contributed from Al-Nb covalent bonds and Al-Al metallic interactions.

  18. Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions

    NASA Astrophysics Data System (ADS)

    Pstruś, Janusz; Gancarz, Tomasz

    2014-05-01

    The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.

  19. Genetics of Familial and Sporadic ALS

    ClinicalTrials.gov

    2017-01-04

    Amyotrophic Lateral Sclerosis (ALS); Familial Amyotrophic Lateral Sclerosis; Amyotrophic Lateral Sclerosis With Frontotemporal Dementia; Lou Gehrig's Disease; Motor Neuron Disease; Primary Lateral Sclerosis

  20. Spin-dependent tunneling junctions with AlN and AlON barriers

    NASA Astrophysics Data System (ADS)

    Sharma, Manish; Nickel, Janice H.; Anthony, Thomas C.; Wang, Shan X.

    2000-10-01

    We report on ferromagnetic spin-dependent tunneling (SDT) junctions with NiFe/AlN/NiFe and NiFe/AlON/NiFe structures. Good barriers were formed by plasma nitridation and oxy-nitridation of Al films. Tunneling magnetoresistance ratios (TMR) up to 18% were observed at room temperature. The devices exhibit lower resistance-area products than those seen in reference junctions with Al2O3 barriers. The degradation in TMR at higher bias voltages is found to be less than that found in standard alumina junctions. AlN and AlON could thus be alternate materials for the tunnel barrier in SDT junctions.

  1. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  2. Atomic structure and oxygen deficiency of the ultrathin aluminium oxide barrier in Al/AlOx/Al Josephson junctions

    NASA Astrophysics Data System (ADS)

    Zeng, Lunjie; Tran, Dung Trung; Tai, Cheuk-Wai; Svensson, Gunnar; Olsson, Eva

    2016-07-01

    Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits.

  3. Atomic structure and oxygen deficiency of the ultrathin aluminium oxide barrier in Al/AlOx/Al Josephson junctions.

    PubMed

    Zeng, Lunjie; Tran, Dung Trung; Tai, Cheuk-Wai; Svensson, Gunnar; Olsson, Eva

    2016-07-12

    Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits.

  4. Atomic structure and oxygen deficiency of the ultrathin aluminium oxide barrier in Al/AlOx/Al Josephson junctions

    PubMed Central

    Zeng, Lunjie; Tran, Dung Trung; Tai, Cheuk-Wai; Svensson, Gunnar; Olsson, Eva

    2016-01-01

    Al/AlOx/Al Josephson junctions are the building blocks of a wide range of superconducting quantum devices that are key elements for quantum computers, extremely sensitive magnetometers and radiation detectors. The properties of the junctions and the superconducting quantum devices are determined by the atomic structure of the tunnel barrier. The nanoscale dimension and disordered nature of the barrier oxide have been challenges for the direct experimental investigation of the atomic structure of the tunnel barrier. Here we show that the miniaturized dimension of the barrier and the interfacial interaction between crystalline Al and amorphous AlOx give rise to oxygen deficiency at the metal/oxide interfaces. In the interior of the barrier, the oxide resembles the atomic structure of bulk aluminium oxide. Atomic defects such as oxygen vacancies at the interfaces can be the origin of the two-level systems and contribute to decoherence and noise in superconducting quantum circuits. PMID:27403611

  5. Effects of renal impairment on aluminum (Al) kinetics and Al-induced toxicity

    SciTech Connect

    Yokel, R.A.; McNamara, P.J.

    1986-03-01

    Al-induced toxicity most commonly occurs in the renally impaired. To study the influence of renal impairment on Al kinetics and toxicity, renally impaired rabbits were prepared by the remnant kidney procedure. Six weeks after partial nephrectomy creatinine clearance was 21% of controls and serum creatinine, BUN, Ca, and PO/sub 4/ were 222, 248, 122, and 50% of presurgery levels respectively. Serum Al kinetics after i.v. Al were: Al clearance 27%, initial and steady state volumes of distribution 50 and 80%, half life 362% and mean residence time 300% of controls (renally intact rabbits). Beginning 9 weeks after partial nephrectomy, rabbits received 145 to 160 ..mu..mole Al/kg s.c. daily, 5 x weekly x 4 weeks. Acquisition of a classically conditioned reflex (nictitating membrane extension) was impaired comparable to that produced by 100-200 ..mu..mole Al in controls but retention and extinction deficits were greater than those seen after 400 ..mu..mole Al in controls. Tissue Al concentrations were less than those seen after 200 ..mu..mole Al in controls. Body weight was comparable to that produced by 400 ..mu..mole Al in controls. These results suggest that renal impairment alters Al serum distribution, impairs its clearance, and increases the Al-induced impairment of memory and body weight gain.

  6. Influence of AlN thickness on AlGaN epilayer grown by MOCVD

    NASA Astrophysics Data System (ADS)

    Jayasakthi, M.; Juillaguet, S.; Peyre, H.; Konczewicz, L.; Baskar, K.; Contreras, S.

    2016-10-01

    AlGaN/AlN layers were grown by metalorganic chemical vapor deposition (MOCVD) on sapphire substrates. The AlN buffer thickness was varied from 400 nm to 800 nm. The AlGaN layer thickness was 1000 nm. The crystalline quality, thickness and composition of AlGaN were determined using high resolution X-ray diffraction (HRXRD). The threading dislocation density (TDD) was found to decrease with increase of AlN layer thickness. Reciprocal space mapping (RSM) was used to estimate the strain and relaxation between AlGaN and AlN. The optical properties of AlGaN layers were investigated by temperature dependent photoluminescence (PL). PL intensities of AlGaN layers increases with increasing the AlN thickness. The surface morphology of AlGaN was studied by atomic force microscopy (AFM). Root mean square (RMS) roughness values were found to be decreased while increase of AlN thickness.

  7. Durability Assessment of TiAl Alloys

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.

    2008-01-01

    The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

  8. Diana Al-Hadid: Identity and Heritage

    ERIC Educational Resources Information Center

    Jungerberg, Tom; Smith, Anna; Borsh, Colleen

    2012-01-01

    Diana Al-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, Al-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images and…

  9. Sporadic and hereditary amyotrophic lateral sclerosis (ALS).

    PubMed

    Ajroud-Driss, Senda; Siddique, Teepu

    2015-04-01

    Genetic discoveries in ALS have a significant impact on deciphering molecular mechanisms of motor neuron degeneration. The identification of SOD1 as the first genetic cause of ALS led to the engineering of the SOD1 mouse, the backbone of ALS research, and set the stage for future genetic breakthroughs. In addition, careful analysis of ALS pathology added valuable pieces to the ALS puzzle. From this joint effort, major pathogenic pathways emerged. Whereas the study of TDP43, FUS and C9ORF72 pointed to the possible involvement of RNA biology in motor neuron survival, recent work on P62 and UBQLN2 refocused research on protein degradation pathways. Despite all these efforts, the etiology of most cases of sporadic ALS remains elusive. Newly acquired genomic tools now allow the identification of genetic and epigenetic factors that can either increase ALS risk or modulate disease phenotype. These developments will certainly allow for better disease modeling to identify novel therapeutic targets for ALS. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.

  10. Energetics of Al13 Keggin cluster compounds

    PubMed Central

    Armstrong, Christopher R.; Casey, William H.; Navrotsky, Alexandra

    2011-01-01

    The ϵ-Al13 Keggin aluminum hydroxide clusters are essential models in establishing molecular pathways for geochemical reactions. Enthalpies of formation are reported for two salts of aluminum centered ϵ-Keggin clusters, Al13 selenate, (Na(AlO4)Al12(OH)24(SeO4)4•12H2O) and Al13 sulfate, (NaAlO4Al12(OH)24(SO4)4•12H2O). The measured enthalpies of solution, ΔHsol, at 28 °C in 5 N HCl for the ε-Al13 selenate and sulfate are −924.57 (± 3.83) and −944.30 ( ± 5.66) kJ·mol-1, respectively. The enthalpies of formation from the elements, ΔHf,el, for Al13 selenate and sulfate are −19,656.35 ( ± 67.30) kJ·mol-1, and −20,892.39 ( ± 70.01) kJ·mol-1, respectively. In addition, ΔHf,el for sodium selenate decahydrate was calculated using data from high temperature oxide melt solution calorimetry measurements: −4,006.39 ( ± 11.91) kJ·mol-1. The formation of both ε-Al13 Keggin cluster compounds is exothermic from oxide-based components but energetically unfavorable with respect to a gibbsite-based assemblage. To understand the relative affinity of the ϵ-Keggin clusters for selenate and sulfate, the enthalpy associated with two S-Se exchange reactions was calculated. In the solid state, selenium is favored in the Al13 compound relative to the binary chalcogenate, while in 5 N HCl, sulfur is energetically favored in the cluster compound compared to the aqueous solution. This contribution represents the first thermodynamic study of ε-Al13 cluster compounds and establishes a method for other such molecules, including the substituted versions that have been created for kinetic studies. Underscoring the importance of ε-Al13 clusters in natural and anthropogenic systems, these data provide conclusive thermodynamic evidence that the Al13 Keggin cluster is a crucial intermediate species in the formation pathway from aqueous aluminum monomers to aluminum hydroxide precipitates. PMID:21852572

  11. Chemical procedure for extracting 129I, 60Fe and 26Al from marine sediments: Prospects for detection of a ˜2.8 My old supernova

    NASA Astrophysics Data System (ADS)

    Fitoussi, Caroline; Raisbeck, Grant M.

    2007-06-01

    For the past three years, we have been developing a procedure to measure carrier-free 129I/I in gram size quantities of marine sediments containing microgram quantities of iodine. Potential applications involve dating of old (>10 My) sediments and the detection of 129I (t1/2 = 15.7 My) from a purported supernova (SN) explosion ˜2.8 million years ago, that has been inferred from a 60Fe (t1/2 = 1.5 My) signal in a deep-sea ferromanganese crust [K. Knie, G. Korschinek, T. Faestermann, E.A. Dorfi, G. Rugel, A. Wallner, Phys. Rev. Lett. 93 (2004) 171103]. The procedure consists in washing the sediment with a NH2OH · HCl HOAc mixture, extraction of iodine from the organic phase with TMAH, separation and purification using anion-exchange chromatography, and coprecipitation as AgI Ag2O. We realized the washing step, which extracts authigenic iron and aluminum, could also be used to measure 60Fe/56Fe and 26Al/27Al in this phase of the same sediment sample. We outline here the chemical procedures developed, and briefly comment on their possible application to the supernova problem. We also point out a large discrepancy between the theoretically calculated 129I/127I ratio in pre-anthropogenic marine sediments, and that derived from experimental measurements.

  12. Dose-enhancement effects in TaSi/Al- and Al-gate MOS devices

    SciTech Connect

    Fleetwood, D.M.; Beutler, D.E.; Draper, B.L.; Knott, D.; Brown, D.B.; Rosenstock, H.

    1988-01-01

    The response of MOS capacitors with TaSi/Al and Al electrodes to medium- and low-energy x-irradiation is investigated. Experimentally measured dose-enhancement effects are compared with computer simulations for these structures.

  13. Phase stability in binary Ti-Al

    NASA Technical Reports Server (NTRS)

    Anderson, C. D.; Hofmeister, W. H.; Bayuzick, R. J.

    1991-01-01

    Binary Ti-Al samples containing from 46 to 54 at. pct Al were solidified while undercooled by various amounts using electromagnetic levitation techniques. A detailed thermal history of these samples was obtained with sampling rates as high as 500 KHz during recalescence. This very high sampling rate was essential to resolve the thermal events. Primary alpha solidification was observed in samples containing from 51 to 54 at. pct Al that were undercooled less than about 100 K at solidification. Primary beta solidification was found for all undercoolings tested in samples containing less than 51 at. pct Al and for undercoolings greater than about 100 K in samples containing 51 to 54 at. pct Al.

  14. The neuropathology of FTD associated With ALS.

    PubMed

    Mackenzie, Ian R A

    2007-01-01

    There is increasing recognition of a clinical overlap between frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Recent advances in our understanding of the neuropathologic, biochemical, and genetic basis of these conditions provides evidence for a common underlying pathogenesis. The neuropathology in most cases of FTD with ALS is a subtype of frontotemporal lobar degeneration, characterized by neuronal inclusions that are immunoreactive for ubiquitin but not tau (frontotemporal lobar degeneration with ubiquitinated inclusions). These cases show significant pathologic overlap with clinically pure FTD and those with classic ALS. Moreover, the ubiquitinated pathologic protein in all these conditions has recently been identified as TDP-43. A number of families have been reported with autosomal dominant FTD-ALS linked to chromosome 9p and these also have TDP-43-positive frontotemporal lobar degeneration with ubiquitinated inclusions pathology. Together, these findings suggest that FTD-ALS is part of a clinicopathologic spectrum of disease, now identified as TDP-43 proteinopathies.

  15. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

    Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the

  16. An Unusual Ca-Ti-Al Silicate in a Type A Allende Inclusion

    NASA Astrophysics Data System (ADS)

    Floss, C.; El Goresy, A.; Palme, H.; Spettel, B.; Zinner, E.

    1992-07-01

    , up to 100 microns in size, are enclosed in altered melilite. The mineral also occurs as a long (120 microns) symplectite in unaltered melilite. Finally, it is found as a symplectitic rim around a large fassaite grain, again associated with alteration. In all occurrences it appears to replace perovskite. Major element chemistry is similar in all grains measured: CaO: 29.18-34.57 wt%; TiO2: 25.99-34.11 wt%; SiO2: 26.00-29.58 wt%; Al2O3: 3.76-9.16 wt%. Approximately 1 wt% MgO and 1.5 wt% V2O3 are also present. Both symplectites have slightly higher Al and lower Ti concentrations than the other grains. The symplectite surrounding fassaite also contains 1.5 wt% Sc2O3, not seen otherwise; the fassaite itself contains up to 1 wt% Sc2O3. El Goresy et al.(1984) and Paque et al. (1986) found small (<20 micron) grains of an unknown Ti- and Al-rich silicate as inclusions in melilite from a number of CAIs, although no association with perovskite was noted. Their mineral contains higher Al (16-19 wt% Al2O3) and lower Ti (20- 27 wt% TiO2) than the one described here. Based on a cation/oxygen ratio of 9/14 (Paque et al., 1986), it appears that up to 1/3 of the Ti may be present as Ti3+. Additional measurements will be done to determine the trace element (including REE) distributions in this mineral; X-ray investigations of the larger grains are also planned. Allen, J.M. et al. (1978) Proc. 9th Lunar Planet. Sci. Conf., 1209-1233. El Goresy, A. et al. (1984) Geochim. Cosmochim. Acta 48, 2283-2298. Fegley, B. and Palme, H. (1985) Earth Planet. Sci. Lett. 72, 311-326. Paque, J. et al. (1986) Lunar Planet. Sci. Conf. XVII, 646- 647.

  17. Photoelectrical, photophysical and photocatalytic properties of Al based MOFs: MIL-53(Al) and MIL-53-NH{sub 2}(Al)

    SciTech Connect

    An, Yang; Li, Huiliang; Liu, Yuanyuan; Huang, Baibiao; Sun, Qilong; Dai, Ying; Qin, Xiaoyan; Zhang, Xiaoyang

    2016-01-15

    Two Al based MOFs (MIL-53(Al) and MIL-53-NH{sub 2} (Al)) were synthesized, and their photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water were investigated. Different from the ligand to metal charge transfer process previously reported, we proposes a new photocatalytic mechanism based on electron tunneling according to the results of theoretical calculation, steady state and time resolved fluorescence spectra. The organic linkers absorb photons, giving rise to electrons and holes. Then, the photogenerated electrons tunnel through the AlO{sub 6}-octahedra, which not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs. - Graphical abstract: The photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water of two Al based MOFs were investigated. A new photocatalytic mechanism was proposed based on electron tunneling according to the results of both theoretical calculation and steady state, time resolved fluorescence spectra. The electron tunneling process not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs.

  18. Al/Al2O3 Metal Matrix Composites (MMCs) and Macrocomposites for Armor Applications

    DTIC Science & Technology

    2013-09-01

    ceramics (high hardness, high stiffness, low thermal expansion). In this study , Al/Al2O3 MMCs with alumina particle contents ranging from 12% to 46% were...expansion). In this study , Al/Al2O3 MMCs with alumina particle contents ranging from 12% to 46% were fabricated by different processing approaches...the different MMCs. The matrix alloy, alumina volume fraction, densities, mechanical properties , and thermal properties are summarized in Table 2

  19. High temperature creep behaviour of Al-rich Ti-Al alloys

    NASA Astrophysics Data System (ADS)

    Sturm, D.; Heilmaier, M.; Saage, H.; Aguilar, J.; Schmitz, G. J.; Drevermann, A.; Palm, M.; Stein, F.; Engberding, N.; Kelm, K.; Irsen, S.

    2010-07-01

    Compared to Ti-rich γ-TiAl-based alloys Al-rich Ti-Al alloys offer an additional reduction of in density and a better oxidation resistance which are both due to the increased Al content. Polycrystalline material was manufactured by centrifugal casting. Microstructural characterization was carried out employing light-optical, scanning and transmission electron microscopy and XRD analyses. The high temperature creep of two binary alloys, namely Al60Ti40 and Al62Ti38 was comparatively assessed with compression tests at constant true stress in a temperature range between 1173 and 1323 K in air. The alloys were tested in the cast condition (containing various amounts of the metastable phases Al5Ti3 and h-Al2Ti) and after annealing at 1223 K for 200 h which produced (thermodynamically stable) lamellar γ-TiAl + r-Al2Ti microstructures. In general, already the as-cast alloys exhibit a reasonable creep resistance at 1173 K. Compared with Al60Ti40, both, the as-cast and the annealed Al62Ti38 alloy exhibit better creep resistance up to 1323 K which can be rationalized by the reduced lamella spacing. The assessment of creep tests conducted at identical stress levels and varying temperatures yielded apparent activation energies for creep of Q = 430 kJ/mol for the annealed Al60Ti40 alloy and of Q = 383 kJ/mol for the annealed Al62Ti38 material. The latter coincides well with that of Al diffusion in γ-TiAl, whereas the former can be rationalized by the instability of the microstructure containing metastable phases.

  20. Corrosion Studies of 2195 Al-Li Alloy and 2219 Al Alloy with Differing Surface Treatments

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Mendrek, M. J.

    1998-01-01

    Corrosion studies of 2195 Al-Li and 2219 Al alloys have been conducted using the scanning reference electrode technique (SRET) and the polarization resistance (PR) technique. The SRET was used to study corrosion mechanisms, while corrosion rate measurements were studied with the PR technique. Plates of Al203 blasted, soda blasted and conversion coated 2219 Al were coated with Deft primer and the corrosion rates studied with the EIS technique. Results from all of these studies are presented.

  1. Japanese version of the ALS-FTD-Questionnaire (ALS-FTD-Q-J).

    PubMed

    Watanabe, Yasuhiro; Beeldman, Emma; Raaphorst, Joost; Izumi, Yuishin; Yoshino, Hiide; Masuda, Michihito; Atsuta, Naoki; Ito, Satoru; Adachi, Tadashi; Adachi, Yoshiki; Yokota, Osamu; Oda, Masaya; Hanashima, Ritsuko; Ogino, Mieko; Ichikawa, Hiroo; Hasegawa, Kazuko; Kimura, Hideki; Shimizu, Toshio; Aiba, Ikuko; Yabe, Hayato; Kanba, Makoto; Kusumi, Kimiyoshi; Aoki, Tetsuya; Hiroe, Yu; Watanabe, Hirohisa; Nishiyama, Kazutoshi; Nomoto, Masahiro; Sobue, Gen; Nakashima, Kenji

    2016-08-15

    Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share common clinical, genetic and neuropathological features. Some ALS patients have behavioral/personality changes, which could result in significant obstacles in the care provided by family members and caregivers. An easy screening tool would contribute greatly to the evaluation of these symptoms. We translated the ALS-FTD-Questionnaire, developed in the Netherlands, into Japanese (ALS-FTD-Q-J) and examined the clinimetric properties (internal consistency, construct and clinical validity). Patients with ALS and/or behavioral variant FTD (bvFTD) were evaluated alongside healthy controls in this multicenter study. All ALS patients, regardless of bvFTD status, were further evaluated by the frontal behavioral inventory (FBI) and for frontal/executive function, cognition, anxiety/depression, and motor functions. Data from 146 subjects were analyzed: ALS (92), ALS-bvFTD (6), bvFTD (16), and healthy controls (32). The internal consistency of the ALS-FTD-Q-J was good (Cronbach α=0.92). The ALS-FTD-Q-J showed construct validity as it exhibited a high correlation with the FBI (r=0.79). However, correlations were moderate with anxiety/depression and low with cognitive scales, in contrast to the original report, i.e. a moderate correlation with cognition and a low correlation with anxiety/depression. The ALS-FTD-Q-J discriminated ALS patients from (ALS-)bvFTD patients and controls. Thus, the ALS-FTD-Q-J is useful for evaluating Japanese ALS/FTD patients.

  2. Alanes formation on the Al(111) surface

    NASA Astrophysics Data System (ADS)

    Rangan, Sylvie; Veyan, Jean-Francois; Chabal, Yves J.; Chaudhuri, Santanu; Muckerman, James T.

    2008-03-01

    Alane clusters (AlxHy) are believed to be the ubiquitous intermediates in hydrogen storage reactions for a wide variety of alanates (LiAlH4, NaAlH4) currently considered for hydrogen storage. The formation and behavior of alanes at surfaces appear to control and limit the efficiency of hydrogen storage. In particular, hydrogen adsorption on the Al(111) surface leads to the coexistence of several adsorbed species, the concentration of which is affected by the step density, the surface coverage and the temperature. We combine density functional theory (DFT) and surface infra-red (IR) absorption spectroscopy to uncover the mechanisms for alane formation on Al(111) surfaces. At low coverage, DFT predicts a two-fold bridge site adsorption for atomic hydrogen, consistent with previous Electron Energy Loss Spectroscopy measurements. At higher coverage, the formation of small chemisorbed AlH3 occurs at the step edges. With increasing coverage AlH3 is extracted from the step edge and becomes highly mobile on the terraces in a weakly bound state. This mobility is the key factor leading to the growth of larger alanes through AlH3 oligomerization. For these large alanes, previous Thermal Programmed Desorption studies are discussed and compared to the thermal stability observed in IR.

  3. Effects of hydrogen absorption in TbNiAl and UNiAl

    SciTech Connect

    Bordallo, H.N.; Nakotte, H.; Schultz, A.; Kolomiets, A.V.; Havela, L.; Andreev, A.V.

    1998-12-31

    Although hydrides of intermetallic compounds are used extensively as hydrogen-storage media, little is known about the exact nature of metal-hydrogen interactions. However, this knowledge is of essential importance for the understanding of thermodynamics and other properties. Hydrides (deuterides) of TbNiAl and UNiAl have been widely studied because of drastic increase of magnetic ordering temperature under hydrogenation. Here the authors report neutron-diffraction results of the three deuterides, TbNiAlD{sub 1.28}, TbNiAlD{sub 0.8}a nd UNiAlD{sub 2.23}.

  4. Phase diagrams of Al-Si and Al-Ge systems

    NASA Astrophysics Data System (ADS)

    Kagaya, Hiroko-Matsuo; Imazawa, Kazumoto; Sato, Mayumi; Soma, Toshinobu

    1998-03-01

    Considering the contributions from the band and local mode frequencies, the temperature- and pressure-dependent mean-square displacement for Al-Si and Al-Ge solid solutions is quantitatively calculated to be similar to that for matrix Al. Then, the concentration-dependence of the Debye temperature at higher and lower temperatures is estimated, the pressure effect on the solidus curve is presented by applying Lindeman's melting law to the Al-Si and Al-Ge alloy systems. The solidus curve obtained increases as a function of the pressure, and is in good agreement with the observed tendency for these solid solutions.

  5. A new discontinuously reinforced aluminum MMC: Al+AlB{sub 2} flakes

    SciTech Connect

    HALL,AARON C.; ECONOMY,J.

    2000-06-08

    Development of a novel metal matrix composite based on the Al-B alloy system has been undertaken. Preparation of this discontinuously reinforced material is based on the precipitation of high aspect ratio AlB{sub 2} from an Al-B alloy. This paper describes a number of efforts forced on preparing high volume fractions (> 30 v%) of AlB{sub 2} in aluminum. New insights into the behavior of the Al-B alloys system allowed this effort to be successful.

  6. Atomistic Modeling of RuAl and (RuNi) Al Alloys

    NASA Technical Reports Server (NTRS)

    Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Atomistic modeling of RuAl and RuAlNi alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 RuAl as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)Al(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25Al50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.

  7. Decoding ALS: from genes to mechanism.

    PubMed

    Taylor, J Paul; Brown, Robert H; Cleveland, Don W

    2016-11-10

    Amyotrophic lateral sclerosis (ALS) is a progressive and uniformly fatal neurodegenerative disease. A plethora of genetic factors have been identified that drive the degeneration of motor neurons in ALS, increase susceptibility to the disease or influence the rate of its progression. Emerging themes include dysfunction in RNA metabolism and protein homeostasis, with specific defects in nucleocytoplasmic trafficking, the induction of stress at the endoplasmic reticulum and impaired dynamics of ribonucleoprotein bodies such as RNA granules that assemble through liquid-liquid phase separation. Extraordinary progress in understanding the biology of ALS provides new reasons for optimism that meaningful therapies will be identified.

  8. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

  9. Arsenate uptake by Al nanoclusters and other Al-based sorbents during water treatment.

    PubMed

    Mertens, Jasmin; Rose, Jérôme; Wehrli, Bernhard; Furrer, Gerhard

    2016-01-01

    In many parts of the world, arsenic from geogenic and anthropogenic sources deteriorates the quality of drinking water resources. Effective methods of arsenic removal include adsorption and coagulation with iron- and aluminum-based materials, of which polyaluminum chloride is widely employed as coagulant in water treatment due to its low cost and high efficiency. We compared the arsenic uptake capacity and the arsenic bonding sites of different Al-based sorbents, including Al nanoclusters, polyaluminum chloride, polyaluminum granulate, and gibbsite. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed that As(V) forms bidentate-binuclear complexes in interaction with all Al-based removal agents. The octahedral configuration of nanoclusters and the distribution of sorption sites remain the same in all types of removal agents consisting of nano-scale Al oxyhydroxide particles. The obtained distances for As(V)-O and As(V)-Al agreed with previously published data and were found to be 1.69 ± 0.02 Å and 3.17-3.21 Å, respectively. Our study suggests that As(V) binds to Al nanoclusters as strongly as to Al oxide surfaces. The As sorption capacity of Al nanoclusters was found to be very similar to that of Al clusters in a polyaluminum chloride. The most efficient Al-based sorbents for arsenic removal were Al nanoclusters, followed by polyaluminum granulate.

  10. InAlN/AlN/GaN heterostructures for high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Usov, S. O.; Sakharov, A. V.; Tsatsulnikov, A. F.; Lundin, V. W.; Zavarin, E. E.; Nikolaev, A. E.; Yagovkina, M. A.; Zemlyakov, V. E.; Egorkin, V. I.; Ustinov, V. M.

    2016-08-01

    The results of development of InAlN/AlN/GaN heterostructures, grown on sapphire substrates by metal-organic chemical vapour deposition, and high electron mobility transistors (HEMTs) based on them are presented. The dependencies of the InAlN/AlN/GaN heterostructure properties on epitaxial growth conditions were investigated. The optimal indium content and InAlN barrier layer thicknesses of the heterostructures for HEMT s were determined. The possibility to improve the characteristics of HEMTs by in-situ passivation by Si3N4 thin protective layer deposited in the same epitaxial process was demonstrated. The InAlN/AlN/GaN heterostructure grown on sapphire substrate with diameter of 100 mm were obtained with sufficiently uniform distribution of sheet resistance. The HEMTs with saturation current of 1600 mA/mm and transconductance of 230 mS/mm are demonstrated.

  11. Oxidation of Al2O3 continuous fiber-reinforced/NiAl composites

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Nesbitt, J. A.; Noebe, R. D.; Bowman, R. R.

    1992-01-01

    The 1200 C and 1300 C isothermal and cyclic oxidation behavior of Al2O3 continuous fiber-reinforced/NiAl composites were studied. Oxidation resulted in formation of Al2O3 external scales in a similar manner as scales formed on monolithic NiAl. The isothermal oxidation of an Al2O3/NiAl composite resulted in oxidation of the matrix along the fiber/matrix interface near the fiber ends. This oxide acted as a wedge between the fiber and the matrix, and, under cyclic oxidation conditions, led to further oxidation along the fiber lengths and eventual cracking of the composite. The oxidation behavior of composites in which the Al2O3 fibers were sputter coated with nickel prior to processing was much more severe. This was attributed to open channels around the fibers which formed during processing, most likely as a result of the diffusion of the nickel coating into the matrix.

  12. Elimination of AlGaN epilayer cracking by spatially patterned AlN mask

    NASA Astrophysics Data System (ADS)

    Sarzyński, Marcin; Kryśko, Marcin; Targowski, Grzegorz; Czernecki, Robert; Sarzyńska, Agnieszka; Libura, Adam; Krupczyński, Wiktor; Perlin, Piotr; Leszczyński, Michał

    2006-03-01

    The inherent problem in III-nitride technology is the cracking of AlGaN layers that results from lattice mismatch between AlGaN and GaN. In case of thin substrates (30-90μm), such as, bulk GaN grown by the high-pressure/high-temperature method, the bowing of AlGaN /GaN strained structures becomes an additional problem. To eliminate cracking and bowing, AlGaN layers were grown on GaN substrates with an AlN mask patterned to form 3-15μm wide windows. In the 3μm window, the AlGaN layer was not cracked, although its thickness and Al composition exceeded critical values for growth on nonpatterned substrates. Dislocation density in the windows was of 5×106/cm2.

  13. Diffusion at the Al/Al oxide interface during electromigration in wide lines

    NASA Astrophysics Data System (ADS)

    Augur, R. A.; Wolters, R. A. M.; Schmidt, W.; Dirks, A. G.; Kordić, S.

    1996-03-01

    Significant large-scale modification of the surface of Al-Si conductors was observed, due to electromigration in wide lines and under low stress conditions. After electromigration stressing the Al layers showed local thickness variations, i.e., damage by thinning. The mechanism underlying this damage causes substantial metal transport. Nevertheless, damage by thinning has received little attention in the past. Thinning was observed: (1) in a number of different alloys (Al-Si, Al-Cu, Al-Si-V, and Al-Si-V-Pd), (2) with a number of different underlayers [SiO2, W-Ti (no vacuum break after Al deposition) and W-Ti (oxidized surface before Al deposition)], (3) over an extended temperature range, (4) over a range of current density, and (5) in structures with and without passivation. The results show that thinning is a general phenomenon. An activation energy of approximately 0.5 eV was determined for the temperature dependence of a combined mechanism of concurrent thinning plus voiding in Al99Si1. Several alternatives are examined to explain the observations, namely mass movement along dislocations, Al bulk diffusion, and diffusion at the interface between the Al and its oxide. It is shown that diffusion at the Al/Al oxide interface most probably plays an important role in the damage mechanism, even under stress conditions where grain boundary diffusion is traditionally thought to dominate. Results also showed that alloying of Al with Pd can reduce the effects of damage by thinning.

  14. Interdiffusion in Diffusion Couples: U-Mo v. Al and Al-Si

    SciTech Connect

    D. D. Keiser, Jr.; E. Perez; B. Yao; Y. H. Sohn

    2009-11-01

    Interdiffusion and microstructural development in the U-Mo-Al system was examined using solid-tosolid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure Al, annealed at 600°C for 24 hours. The influence of Si alloying addition (up to 5 wt.%) in Al on the interdiffusion microstructural development was also examined using solid-to-solid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure Al, Al-2wt.%Si, and Al-5wt.%Si annealed at 550°C up to 20 hours. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) were employed to examine the development of a very fine multiphase intermetallic layer. In ternary U-Mo-Al diffusion couples annealed at 600°C for 24 hours, interdiffusion microstructure varied of finely dispersed UAl3, UAl4, U6Mo4Al43, and UMo2Al20 phases while the average composition throughout the interdiffusion zone remained constant at approximately 80 at.% Al. Interdiffusion microstructure observed by SEM/TEM analyses and diffusion paths drawn from concentration profiles determined by EPMA appear to deviate from the assumption of “local thermodynamic equilibrium,” and suggest that interdiffusion occurs via supersaturated UAl4 followed by equilibrium transformation into UAl3, U6Mo4Al43, UAl4 and UMo2Al20 phases. Similar observation was made for U-Mo vs. Al diffusion couples annealed at 550°C. The addition of Si (up to 5 wt.%) in Al significantly reduced the thickness of the intermetallic layer by changing the constituent phases of the interdiffusion zone developed in U-Mo vs. Al-Si diffusion couples. Specifically, the formation of (U,Mo)(Al,Si)3 with relatively large solubility for Mo and Si, along with UMo2Al20 phases was observed along with disappearance of U6Mo4Al43 and UAl4 phases. Simplified understanding based on U-Al, U-Si, and Mo-Si binary phase diagrams is discussed in the light of the beneficial effect of Si alloying addition.

  15. On Dobbert et al, 'Cultural Transmission...'

    ERIC Educational Resources Information Center

    Gearing, Frederick

    1984-01-01

    Criticizes Dobbert et al's model of cultural transmission (presented in earlier article) as being a species of social physics. Suggests improvements to the model, notably that observation and analysis at the emic level be taken into account. (RDN)

  16. Pike International, LLC et al. Information Sheet

    EPA Pesticide Factsheets

    Pike International LLC, et al. (the Company) is located in New Haven, Connecticut. The Complaint involves the lease of, and renovation activities conducted at, property constructed prior to 1978, located in New Haven, Connecticut.

  17. ALS and Oxidative Stress: The Neurovascular Scenario

    PubMed Central

    Thakur, Keshav; Gupta, Pawan Kumar

    2013-01-01

    Oxidative stress and angiogenic factors have been placed as the prime focus of scientific investigations after an establishment of link between vascular endothelial growth factor promoter (VEGF), hypoxia, and amyotrophic lateral sclerosis (ALS) pathogenesis. Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter and mutant superoxide dismutase 1 (SOD1) which are characterised by atrophy and muscle weakness resulted in phenotype resembling human ALS in mice. This results in lower motor neurodegeneration thus establishing an important link between motor neuron degeneration, vasculature, and angiogenic molecules. In this review, we have presented human, animal, and in vitro studies which suggest that molecules like VEGF have a therapeutic, diagnostic, and prognostic potential in ALS. Involvement of vascular growth factors and hypoxia response elements also highlights the converging role of oxidative stress and neurovascular network for understanding and treatment of various neurodegenerative disorders like ALS. PMID:24367722

  18. 12th Annual ALS Users' Association Meeting

    SciTech Connect

    Robinson, Arthur L.

    1999-12-17

    Science took the front seat as 219 Advanced Light Source (ALS) users and staff gathered on Monday and Tuesday, October 18 and 19 for the twelfth annual users' meeting. The bulk of the meeting was dedicated to reports on science at the ALS. Packed into two busy days were 31 invited oral presentations and 80 submitted poster presentations, as well as time to visit 24 vendor booths. The oral sessions were dedicated to environmental science, chemical dynamics, biosciences, magnetic materials, and atomic and molecular science. In addition, there was an ALS highlights session that emphasized new results and a session comprising highlights from the young scientists who will carry the ALS into the future.

  19. Half life of /sup 26/Al

    SciTech Connect

    Norris, T.L.; Gancarz, A.J.; Rokop, D.J.; Thomas, K.W.

    1983-01-01

    The half-life of /sup 26/Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating /sup 21/Ne production rates from cosmic rays in meteorites. Two solutions of /sup 26/Al were analyzed for the specific radioactivity and mass spectrometric determination of the /sup 26/Al concentration. The half-life obtained for /sup 26/Al was 7.05 x 10/sup 5/ years +- 3.7% at the two sigma level. This is identical to the accepted value of 7.16 x 10/sup 5/ years and indicates that problems with the /sup 21/Ne production rate is not due to an erroneous half-life.

  20. Al Qaeda: A Modern Day Lernaean Hydra

    DTIC Science & Technology

    2010-03-01

    insurgency. Still others have referred to it as a netwar organization waging conflict primarily through the use of networks. A few authors have...organization waging conflict primarily through the use of networks. A few authors have characterized it as a religious movement. Like the Hydra, Al...Al Qaeda as an insurgency. Still others have referred to it as a Netwar organization waging conflict primarily through the use of networks.1 A

  1. Patterns of inheritance in familial ALS.

    PubMed

    Bradley, Marcus; Bradley, Lloyd; de Belleroche, Jackie; Orrell, Richard W

    2005-05-10

    We investigated 185 families with ALS for evidence of anticipation and mitochondrial inheritance. Although initial analysis demonstrated significant anticipation of age at death between generations in patients with familial ALS, further analysis demonstrated features of regression to the mean, suggesting that the perceived differences are the result of bias. In addition, there was no evidence of an effect of preferential maternal inheritance, which would have supported transmission of mitochondrial DNA mutations.

  2. 17th Annual ALS Users' Association Meeting

    SciTech Connect

    Robinson, Art; Tamura, Lori

    2004-11-29

    It's not exactly Russian roulette, but scheduling October events outdoors is not risk-free, even in usually sunny California. An overflow crowd of more than 400 registered users, ALS staff, and vendors enjoyed a full indoor program featuring science highlights and workshops spread over two and a half days from October 18 to October 20. However, a major storm, heralding the onset of the San Francisco Bay Area rainy season, posed a few weather challenges for the events on the ALS patio.

  3. Analysis of hydrodynamic fluctuations in heterogeneous adjacent multidomains in shear flow

    NASA Astrophysics Data System (ADS)

    Bian, Xin; Deng, Mingge; Tang, Yu-Hang; Karniadakis, George Em

    2016-03-01

    We analyze hydrodynamic fluctuations of a hybrid simulation under shear flow. The hybrid simulation is based on the Navier-Stokes (NS) equations on one domain and dissipative particle dynamics (DPD) on the other. The two domains overlap, and there is an artificial boundary for each one within the overlapping region. To impose the artificial boundary of the NS solver, a simple spatial-temporal averaging is performed on the DPD simulation. In the artificial boundary of the particle simulation, four popular strategies of constraint dynamics are implemented, namely the Maxwell buffer [Hadjiconstantinou and Patera, Int. J. Mod. Phys. C 08, 967 (1997), 10.1142/S0129183197000837], the relaxation dynamics [O'Connell and Thompson, Phys. Rev. E 52, R5792 (1995), 10.1103/PhysRevE.52.R5792], the least constraint dynamics [Nie et al., J. Fluid Mech. 500, 55 (2004), 10.1017/S0022112003007225; Werder et al., J. Comput. Phys. 205, 373 (2005), 10.1016/j.jcp.2004.11.019], and the flux imposition [Flekkøy et al., Europhys. Lett. 52, 271 (2000), 10.1209/epl/i2000-00434-8], to achieve a target mean value given by the NS solver. Going beyond the mean flow field of the hybrid simulations, we investigate the hydrodynamic fluctuations in the DPD domain. Toward that end, we calculate the transversal autocorrelation functions of the fluctuating variables in k space to evaluate the generation, transport, and dissipation of fluctuations in the presence of a hybrid interface. We quantify the unavoidable errors in the fluctuations, due to both the truncation of the domain and the constraint dynamics performed in the artificial boundary. Furthermore, we compare the four methods of constraint dynamics and demonstrate how to reduce the errors in fluctuations. The analysis and findings of this work are directly applicable to other hybrid simulations of fluid flow with thermal fluctuations.

  4. Shortcomings of the bond orientational order parameters for the analysis of disordered particulate matter

    NASA Astrophysics Data System (ADS)

    Mickel, Walter; Kapfer, Sebastian C.; Schröder-Turk, Gerd E.; Mecke, Klaus

    2013-01-01

    Local structure characterization with the bond-orientational order parameters q4, q6, … introduced by Steinhardt et al. [Phys. Rev. B 28, 784 (1983), 10.1103/PhysRevB.28.784] has become a standard tool in condensed matter physics, with applications including glass, jamming, melting or crystallization transitions, and cluster formation. Here, we discuss two fundamental flaws in the definition of these parameters that significantly affect their interpretation for studies of disordered systems, and offer a remedy. First, the definition of the bond-orientational order parameters considers the geometrical arrangement of a set of nearest neighboring (NN) spheres, NN(p), around a given central particle p; we show that the choice of neighborhood definition can have a bigger influence on both the numerical values and qualitative trend of ql than a change of the physical parameters, such as packing fraction. Second, the discrete nature of neighborhood implies that NN(p) is not a continuous function of the particle coordinates; this discontinuity, inherited by ql, leads to a lack of robustness of the ql as structure metrics. Both issues can be avoided by a morphometric approach leading to the robust Minkowski structure metrics q_l^' }. These q_l^' } are of a similar mathematical form as the conventional bond-orientational order parameters and are mathematically equivalent to the recently introduced Minkowski tensors [G. E. Schröder-Turk et al., Europhys. Lett. 90, 34001 (2010), 10.1209/0295-5075/90/34001; S. Kapfer et al., Phys. Rev. E 85, 030301-R (2012), 10.1103/PhysRevE.85.030301].

  5. Changes in metabolic modules under environmental variations

    NASA Astrophysics Data System (ADS)

    Almaas, Eivind

    2006-03-01

    During the last few years, network approaches have shown great promise as a tool to both analyze and provide understanding of complex systems as disparate as the world-wide web and cellular metabolism. Much effort has been focused on characterizing topological properties of such systems. However, in order to develop detailed descriptions of complex networks, we need to look beyond their topology and incorporate dynamical aspects. The cellular metabolism, where nodes correspond to metabolites and links indicate chemical reactions, is an excellent model system where theoretical predictions can be compared with experimental results. I will present recent insights into the principles governing the modular utilization of the cellular metabolism [1,2,3]. We find that, while most metabolic reactions have small fluxes, the metabolism's activity is dominated by an interconnected sub-network of reactions with very high fluxes [1]. For the bacteria H. pylori and E. coli and the yeast S. cerevisiae, the metabolism responds to changes in growth conditions by reorganizing the rates of select reactions predominantly within this high-flux backbone. Furthermore, these networks are organized around the metabolic core -- a set of reactions that are always in use [2]. Strikingly, the activity of the metabolic core reactions is highly synchronized, and the core reactions are significantly more essential and evolutionary conserved than the non-core ones. [1] E. Almaas, B. Kovacs, T. Vicsek, Z.N. Oltvai and A.-L. Barabasi. Nature 427, 839 (2004). [2] E. Almaas, Z.N. Oltvai and A.-L. Barabasi. PLoS Comput. Biol. In press (2005). 10.1371/journal.pcbi.0010068.eor [3] P.J. Macdonald, E. Almaas and A.-L. Barabasi. Europhys. Lett. 72, 308 (2005).

  6. Modeling of precipitation in Al alloys

    SciTech Connect

    Asta, M.; Foiles, S.M.; Wolfer, W.G.

    1996-10-01

    Objective was the development of a computational model of precipitation from a supersaturated alloy solid solution. The model is based on the formalism of chemical-reaction-rate theory combined with classical descriptions of precipitate thermodynamic properties and a mean-field treatment of diffusion-limited growht and coarsening. For the case of precipitation of Al{sub 3}Sc in supersaturated Al-Sc alloys, it is demonstrated how the model can be used to calculate number densities and size distributions of precipitates as a function of aging time and temperature, including effects of continuous cooling and thermally generated point defects. Application of the model to a specific alloy system requires knowledge of diffusion data, point defect energetics, and thermodynamic properties for bulk phases and interphase interfaces. For interfaces and point defects, thermodynamic data can be difficult to measure and reliable values of defect free energies are often unavailable. For this reason, part of the efforts were devoted to applying semiempirical and first-principles atomistic techniques to the calculation of interfacial and point-defect thermodynamic properties. This report discusses applications for interphase interfaces in the Al-Ag, Al-Sc, and Al-Li alloy systems. We also describe atomistic work aimed at understanding the energetics of vacancy clusters in Al. These clusters serve as sinks for isolated vacancies during aging and their growth can lead to more complex defects, such as dislocation loops, that act as heterogeneous nucleation sites.

  7. Theoretics-directed effect of copper or aluminum content on the ductility characteristics of Al-based (Al3Ti, AlTi, AlCu, AlTiCu2) intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Li, Yong; Ma, Xiao-Juan; Liu, Qi-Jun; Kong, Ge-Xing; Ma, Hai-Xia; Wang, Wen-Peng; Wang, Yi-Gao; Jiao, Zhen; Liu, Fu-Sheng; Liu, Zheng-Tang

    2016-11-01

    First-principle simulations have been applied to investigate the effect of copper (Cu) or aluminum (Al) content on the ductility of Al3Ti, AlTi, AlCu, and AlTiCu2 alloys. The mechanical stable and elastic properties of Al-based intermetallic compounds are researched by density functional theory with the generalized gradient approximation (DFT-GGA). The calculated lattice constants are in conformity with the previous experimental and theoretical data. The deduced elastic constants show that the investigated Al3Ti, AlTi, AlCu, and AlTiCu2 structures are mechanically stable. Shear modulus, Young’s modulus, Poisson’s ratio, and the ratio B/G have also been figured out by using reckoned elastic constants. A further analysis of Young’s modulus and Poisson’s ratio reveals that the third added element copper content has significant effects on the Al-Ti-based ICs ductile character. Project supported by the National Natural Science Foundation of China (Grant Nos. 41674088, 11574254, 11272296, and 11547311), the National Basic Research Program of China (Grant No. 2011CB808201), the Fundamental Research Fund for the Central Universities, China (Grant Nos. 2682014ZT30 and 2682014ZT31), and the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University, China (Grant No. SKLSP201511).

  8. Metastability in the MgAl2O4-Al2O3 System

    DOE PAGES

    Wilkerson, Kelley R.; Smith, Jeffrey D.; Hemrick, James G.

    2014-07-22

    Aluminum oxide must take a spinel form ( γ-Al2O3) at elevated temperatures in order for extensive solid solution to form between MgAl2O4 and α-Al2O3. The solvus line between MgAl2O4 and Al2O3 has been defined at 79.6 wt% Al2O3 at 1500°C, 83.0 wt% Al2O3 at 1600°C, and 86.5 wt% Al2O3 at 1700°C. A metastable region has been defined at temperatures up to 1700°C which could have significant implications for material processing and properties. Additionally, initial processing could have major implications on final chemistry. The spinel solid solution region has been extended to form an infinite solid solution with Al2O3 at elevatedmore » temperatures. A minimum in melting at 1975°C and a chemistry of 96 wt% Al2O3 rather than a eutectic is present, resulting in no eutectic crystal formation during solidification.« less

  9. Temperature dependence of the dielectric response of anodized Al-Al2O3-metal capacitors

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2003-03-01

    The temperature dependence of capacitance, CM, and conductance, GM, of Al-Al2O3-metal capacitors with Cu, Ag, and Au electrodes has been measured between 100 and 340 K at seven frequencies between 10 kHz and 1 MHz. Al2O3 films between 15 and 64 nm thick were formed by anodizing evaporated Al films in borate-glycol or borate-H2O electrolyte. The interface capacitance at the Al2O3-metal interface, CI, which is in series with the capacitance CD due to the Al2O3 dielectric, is determined from plots of 1/CM versus insulator thickness. CI is not fixed for a given metal-insulator interface but depends on the vacuum system used to deposit the metal electrode. CI is nearly temperature independent. When CI is taken into account the dielectric constant of Al2O3 determined from capacitance measurements is ˜8.3 at 295 K. The dielectric constant does not depend on anodizing electrolyte, insulator thickness, metal electrode, deposition conditions for the metal electrode or measurement frequency. By contrast, GM of Al-Al2O3-metal capacitors depends on both the deposition conditions of the metal and on the metal. For Al-Al2O3-Cu capacitors, GM is larger for capacitors with large values of 1/CI that result when Cu is evaporated in an oil-pumped vacuum system. For Al-Al2O3-Ag capacitors, GM does not depend on the Ag deposition conditions.

  10. Correction to Kane et al. (2016).

    PubMed

    Kane, Michael J; Meier, Matt E; Smeekens, Bridget A; Gross, Georgina M; Chun, Charlotte A; Silvia, Paul J; Kwapil, Thomas R

    2016-12-01

    Reports an error in "Individual differences in the executive control of attention, memory, and thought, and their associations with schizotypy" by Michael J. Kane, Matt E. Meier, Bridget A. Smeekens, Georgina M. Gross, Charlotte A. Chun, Paul J. Silvia and Thomas R. Kwapil (Journal of Experimental Psychology: General, 2016[Aug], Vol 145[8], 1017-1048). There were errors in Table 3 and Table 7 (these transcription errors were limited to descriptive statistics in the Tables and did not affect any inferential statistics). In Table 3, the ARRO-TUT and LETT-TUT variables had incorrect values for Mean [95% CI], SD, Skew, Kurtosis, and N. In Table 7, the same values (plus Min and Max) were incorrect for the SEM-SART variable. The correct values for these measures are presented in the correction (the values for Min and Max were correct as set in Table 3, but are repeated below for clarity). (The following abstract of the original article appeared in record 2016-29680-001.) A large correlational study took a latent-variable approach to the generality of executive control by testing the individual-differences structure of executive-attention capabilities and assessing their prediction of schizotypy, a multidimensional construct (with negative, positive, disorganized, and paranoid factors) conveying risk for schizophrenia. Although schizophrenia is convincingly linked to executive deficits, the schizotypy literature is equivocal. Subjects completed tasks of working memory capacity (WMC), attention restraint (inhibiting prepotent responses), and attention constraint (focusing visual attention amid distractors), the latter 2 in an effort to fractionate the "inhibition" construct. We also assessed mind-wandering propensity (via in-task thought probes) and coefficient of variation in response times (RT CoV) from several tasks as more novel indices of executive attention. WMC, attention restraint, attention constraint, mind wandering, and RT CoV were correlated but separable

  11. Effects of Al(III) and nano-Al13 species on malate dehydrogenase activity.

    PubMed

    Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang

    2011-01-01

    The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that Al(III) and Al(13) can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III) and Al(13) concentration increase. Our study also found that the effects of Al(III) and Al(13) on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules.

  12. Microscopic Properties of Long-Period Ordering in Al-Rich TiAl Alloys

    NASA Astrophysics Data System (ADS)

    Hata, S.; Nakano, T.; Kuwano, N.; Itakura, M.; Matsumura, S.; Umakoshi, Y.

    2008-07-01

    The ordering mechanism of long-period superstructures (LPSs) in Al-rich TiAl alloys has been investigated by high-resolution transmission electron microscopy (HRTEM). The LPSs are classified in terms of arrangements of base clusters with different shapes and compositions formed in Ti-rich (002) layers of L10-TiAl matrix: square Ti4Al, fat rhombus Ti3Al, and lean rhombus Ti2Al type clusters. The HRTEM observations revealed that antiphase boundaries of long-range-ordered LPS domains and short-range-ordered microdomains are constructed by various space-filling arrangements of the base clusters. Such a microscopic property characterized by the base clusters and their arrangements is markedly analogous to that of the {left< {{text{1,1/2,0}}} rightrangle } * special-point ordering alloys such as Ni-Mo.

  13. Effects of Al(III) and Nano-Al13 Species on Malate Dehydrogenase Activity

    PubMed Central

    Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang

    2011-01-01

    The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that Al(III) and Al13 can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III) and Al13 concentration increase. Our study also found that the effects of Al(III) and Al13 on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules. PMID:22163924

  14. Protective Al2O3 scale formation on NbAl3-base alloys

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Hebsur, M. G.

    1991-01-01

    The oxidation of NbAl3 with additions of Cr and Y was studied to determine the mechanisms of the beneficial effects of these elements upon oxidation. Cr additions to the binary NbAl3 alloy of up to 6.8 at. percent reduced the scale growth rates and promoted alpha-Al2O3 formation over much longer times relative to binary NbAl3. A major effect of Cr is to form a layer of AlNbCr at the metal/scale interface, which is inherently more oxidation-resistant than the matrix alloy in the long term. Yttrium additions to a Cr-containing alloy improved the scale growth rate and adherence and changed the scale microstructure to mimic that of a typical protective Al2O3 scale.

  15. Magnetic behavior of CoPt-AlN granular structure laminated with AlN layers

    NASA Astrophysics Data System (ADS)

    Yu, Youxing; Shi, Ji; Nakamura, Yoshio

    2011-04-01

    The magnetic behavior of CoPt-AlN granular structure laminated with AlN layers has been studied. Ultrathin multilayer structure, [CoPt0.5 nm/AlN0.5nm]4, is used as the precursor of the magnetic layers, which are separated by 5-nm-thick AlN layers. Upon thermal annealing, the ultrathin multilayer transforms into CoPt-AlN granular structure, and the thick AlN layers remain to be spacers. When the film was annealed at 400 °C, the out-of-plane direction becomes the easy axis of magnetization, although the coercivity remains small. TEM observation has proved that CoPt shows disklike shape at such an annealing temperature. When increasing the annealing temperature to 600 °C and above, the films show "isotropic" magnetic behavior due to the formation of equiaxial CoPt particles in the magnetic layers.

  16. Potential skin involvement in ALS: revisiting Charcot's observation - a review of skin abnormalities in ALS.

    PubMed

    Paré, Bastien; Gros-Louis, François

    2017-03-25

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting motor neurons of the brain and spinal cord, leading to progressive paralysis and death. Interestingly, many skin changes have been reported in ALS patients, but never as yet fully explained. These observations could be due to the common embryonic origin of the skin and neural tissue known as the ectodermal germ layer. Following the first observation in ALS patients' skin by Dr Charcot in the 19th century, in the absence of bedsores unlike other bedridden patients, other morphological and molecular changes have been observed. Thus, the skin could be of interest in the study of ALS and other neurodegenerative diseases. This review summarizes skin changes reported in the literature over the years and discusses about a novel in vitro ALS tissue-engineered skin model, derived from patients, for the study of ALS.

  17. Process Capability Analysis of Vacuum Moulding for Development of Al-Al2O3 MMC

    NASA Astrophysics Data System (ADS)

    Singh, R.

    2013-01-01

    The purpose of the present study is to investigate process capability of vacuum moulding (VM) for development of Al-Al2O3 metal matrix composite (MMC). Starting from the identification of component, prototypes were prepared (with three different input parameters namely: vacuum pressure; component volume and sand grit size to give output in form of dimensional accuracy). Measurements on the coordinate measuring machine helped in calculating the dimensional tolerances of the Al-Al2O3 MMC prepared. Some important mechanical properties were also compared to verify the suitability of the components. Final components produced are acceptable as per ISO standard UNI EN 20286-I (1995). The results of study suggest that VM process lies in ±4.5 sigma (σ) limit as regard to dimensional accuracy of Al-Al2O3 MMC is concerned. This process ensures rapid production of pre-series technological prototypes and proof of concept at less production cost and time.

  18. Relative importance of hydrolyzed Al(III) species (Al(a), Al(b), and Al(c)) during coagulation with polyaluminum chloride: a case study with the typical micro-polluted source waters.

    PubMed

    Yan, Mingquan; Wang, Dongsheng; Qu, Jiuhui; He, Wenjie; Chow, Christopher W K

    2007-12-15

    The relative importance of three different Al species, Al(a) (monomeric species, instantaneous reacted species), Al(b) (medium polymer species, reacted less than 120 min), and Al(c) (colloidal or solid species, no reaction), defined by timed complexation reaction rate measured by using ferron reagent in polyaluminum chloride (PACl) was investigated in terms of DOC (dissolved organic carbon), UV(254), and turbidity removal efficiencies. Micro-polluted, typical North China, source waters were used to conduct the experiments. The results show that DOC removal is correlated well to the content of Al(b). Removal of UV(254) is determined by the content of Al(b) and Al(c), particularly Al(c). Turbidity removal is primarily related to the content of Al(c); however, Al(b) could destabilize particles efficiently, and the flocs formed by Al(b) are not as large as those formed by Al(c), which affected the settling efficiency. Unlike the preformed Al(b), the in situ formed Al(b) could remove turbidity more efficiently since Al(c) is the dominant final species formed during coagulation. Al(a) shows a strong ability to react with some unsatisfied coordinate bonds of organic matter to facilitate particle and DOC removal. The distinct coagulation feature of Al(a), Al(b), and Al(c) can be applied to develop tailor-made PACl (with the correct distribution of Al species) to match the characteristics of raw water for optimized coagulation.

  19. The lowest ionization potentials of Al2

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.

    1988-01-01

    Potential curves for the lowest two electronic states (X 2 sigma g + and A 2 pi u) of Al2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential (to Al2(+) X 2 sigma g +) of the Al2 X 3 pi u ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential (to Al2(+) A 2 pi u) occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of Al3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an Al2 ground electronic state assignment of 3 sigma g -, but the separation between the two lowest states of Al2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3 pi u.

  20. Influence of RCS on Al-3Mg and Al-3Mg-0.25Sc alloys

    NASA Astrophysics Data System (ADS)

    Bhovi, Prabhakar M.; Venkateswarlu, K.

    2016-02-01

    An influence of repetitive corrugation and straightening (RCS) was studied on Al-3Mg and Al-3Mg-0.25Sc alloys up to eight passes. Each pass consist of a corrugation and followed by straightening. This has resulted in introducing large plastic strain in sample, and thus led to formation of sub-micron grain sizes with high angle grain boundaries. These sub grain formation was eventually resulted in improved mechanical properties. The average grain size of Al-3Mg-0.25Sc alloy after 8 passes yielded to ∼0.6pm. Microhardness, strength properties were evaluated and it suggests that RCS was responsible for high hardness values as compared to the as cast samples. The microhardness values after RCS were 105 HV and 130 HV for Al-3Mg and Al-3Mg-0.25Sc alloys, respectively. Similarly, ∼ 40% improvement in tensile strength from 240 MPa to 370 MPa was observed for Al- 3Mg-0.25Sc alloy after RCS process.Al-3Mg and Al-3Mg-0.25Scalloys exhibited maximum strength of 220 MPa and 370 MPa, respectively. It is concluded that RCS process has a strong influence on Al- 3Mg and Al-3Mg-0.25Sc alloys for obtaining improved mechanical properties and grain refinement. In addition to RCS process and presence of AESc precipitates in Al-3Mg-0.25Sc alloy had a significant role in grain refinement and improved mechanical properties as compared to Al-3Mg alloy.

  1. Stabilization of itinerant (band) magnetism in FeAl by Ga substitution for Al

    NASA Astrophysics Data System (ADS)

    Papaconstantopoulos, D. A.; Mazin, I. I.; Hathaway, K. B.

    2001-06-01

    Band structure calculations of FeGa1-xAlx have been performed, to further investigate the stability of ferromagnetism in FeAl. The Stoner parameter increases by about 20% at the FeGa end. This is also confirmed by our spin-polarized calculations. We conclude that Ga substitution for Al is likely to stabilize the elusive (or illusive) ferromagnetic state in FeAl.

  2. Another Security Improvement over the Lin et al.'s E-voting Scheme

    NASA Astrophysics Data System (ADS)

    Asaar, Maryam Rajabzadeh; Mohajeri, Javad; Salmasizadeh, Mahmoud

    In 2003, Lin et al. have proposed an electronic voting scheme which can be utilized in large-scale elections, and claimed it detects double voting. But in this paper, by presenting an attack, we show that voters can successfully vote more than once without being detected. Hence, we propose a new modified scheme based on the Lin et al.'s scheme with the same efficiency to solve this weakness and analyze its security.

  3. Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides

    NASA Technical Reports Server (NTRS)

    Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

    1998-01-01

    A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

  4. Small Al clusters. II - Structure and binding in Al(n) (n = 2-6, 13)

    NASA Technical Reports Server (NTRS)

    Pettersson, Lars G. M.; Bauschlicher, Charles W., Jr.; Halicioglu, Timur

    1987-01-01

    The structure and stability of aluminum clusters containing up to six atoms have been studied using correlated wave functions and extended basis sets. The lowest energy structure is planar for Al4 and Al5, but three dimensional for Al6. The icosahedral, hcp, fcc, and two planar structures of Al13 were considered at the SCF level. The lowest energy structure is the icosahedron, but the planar structures are fairly low lying even in this case. A simplified description using two- and three-body interaction potentials is found to agree well with the ab initio structures and binding energies.

  5. The Dissociation Energies of AlH2 and AlAr

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Partridge, Harry; Bauschlicher, Charles W., Jr.; Visscher, Luuk; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The D(sub 0) values for AlH2 and AlAr are computed using the coupled cluster approach in conjunction with large basis sets. Basis set superposition and spin-orbit effects are accounted for as they are sizeable due to the small binding energy. The computed dissociation energy for AlAr is 101 /cm , which is 83% of the experimental value (122.4/ cm). Our best estimate for the H2 binding energy in AlH2 is 40 +/- 28 /cm.

  6. Synthesis of core-shell AlOOH hollow nanospheres by reacting Al nanoparticles with water

    NASA Astrophysics Data System (ADS)

    Lozhkomoev, A. S.; Glazkova, E. A.; Bakina, O. V.; Lerner, M. I.; Gotman, I.; Gutmanas, E. Y.; Kazantsev, S. O.; Psakhie, S. G.

    2016-05-01

    A novel route for the synthesis of boehmite nanospheres with a hollow core and the shell composed of highly crumpled AlOOH nanosheets by oxidizing Al nanopowder in pure water under mild processing conditions is described. The stepwise events of Al transformation into boehmite are followed by monitoring the pH in the reaction medium. A mechanism of formation of hollow AlOOH nanospheres with a well-defined shape and crystallinity is proposed which includes the hydration of the Al oxide passivation layer, local corrosion of metallic Al accompanied by hydrogen evolution, the rupture of the protective layer, the dissolution of Al from the particle interior and the deposition of AlOOH nanosheets on the outer surface. In contrast to previously reported methods of boehmite nanoparticle synthesis, the proposed method is simple, and environmentally friendly and allows the generation of hydrogen gas as a by-product. Due to their high surface area and high, slit-shaped nanoporosity, the synthesized AlOOH nanostructures hold promise for the development of more effective catalysts, adsorbents, vaccines and drug carriers.

  7. Possible Involvement of Al-Induced Electrical Signals in Al Tolerance in Wheat.

    PubMed Central

    Papernik, L. A.; Kochian, L. V.

    1997-01-01

    The relationship between Al-induced depolarization of root-cell transmembrane electrical potentials (Em) and Al tolerance in wheat (Triticum aestivum L.) was investigated. Al exposure induced depolarizations of Em in the Al-tolerant wheat cultivars Atlas and ET3, but not in the Al-sensitive wheat cultivars Scout and ES3. The depolarizations of Em occured in root cap cells and as far back as 10 mm from the root tip. The depolarization was specific to Al3+; no depolarization was observed when roots were exposed to the rhizotoxic trivalent cation La3+. The Al-induced depolarization occurred in the presence of anion-channel antagonists that blocked the release of malate, indicating that the depolarization is not due to the electrogenic efflux of malate2-. K+-induced depolarizations in the root cap were of the same magnitude as Al-induced depolarizations, but did not trigger malate release, indicating that Al-induced depolarization of root cap cell membrane potentials is probably linked to, but is not sufficient to trigger, malate release. PMID:12223834

  8. High temperature deformation of NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Nix, W. D.

    1982-01-01

    The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

  9. Survey and alignment at the ALS

    SciTech Connect

    Krebs, G.F.; Lauritzen, T.; Thur, W.

    1995-11-01

    This paper describes survey and alignment at the Lawrence Berkeley National Laboratory`s Advanced Light Source (ALS) accelerators from 1993 to 1995. The ALS is a 1.0 - 1.9 GeV electron accelerator producing extremely bright synchrotron light in the UV and soft-X-ray wavelengths. At the ALS, electrons are accelerated in a LINAC to 50 MeV, injected into a booster ring for further acceleration and finally injected into the storage ring. This is shown schematically in Figure 1. The storage ring, some 200 m in circumference, has been run with electron currents above 400 mA with lifetimes as high as 24 hours. The ALS is a third generation light source and requires for efficient storage ring operation, magnets aligned to within 150 mm of their ideal position. To accomplish this a network of monuments was established and their positions measured with respect to one another. The data was reduced using GEONET`` and STAR*NET`` software. Using the monuments as reference points, magnet positions were measured and alignment confirmed using the Kem Electronic Coordinate Determination System (ECDS``). A number of other papers dealing with survey and alignment (S&A) at the ALS have been written that may further elucidate some details of the methods and systems described in this paper.

  10. Exit probability of the one-dimensional q-voter model: Analytical results and simulations for large networks

    NASA Astrophysics Data System (ADS)

    Timpanaro, André M.; Prado, Carmen P. C.

    2014-05-01

    We discuss the exit probability of the one-dimensional q-voter model and present tools to obtain estimates about this probability, both through simulations in large networks (around 107 sites) and analytically in the limit where the network is infinitely large. We argue that the result E(ρ )=ρq/ρq+(1-ρ)q, that was found in three previous works [F. Slanina, K. Sznajd-Weron, and P. Przybyła, Europhys. Lett. 82, 18006 (2008), 10.1209/0295-5075/82/18006; R. Lambiotte and S. Redner, Europhys. Lett. 82, 18007 (2008), 10.1209/0295-5075/82/18007, for the case q =2; and P. Przybyła, K. Sznajd-Weron, and M. Tabiszewski, Phys. Rev. E 84, 031117 (2011), 10.1103/PhysRevE.84.031117, for q >2] using small networks (around 103 sites), is a good approximation, but there are noticeable deviations that appear even for small systems and that do not disappear when the system size is increased (with the notable exception of the case q =2). We also show that, under some simple and intuitive hypotheses, the exit probability must obey the inequality ρq/ρq+(1-ρ)≤E(ρ)≤ρ/ρ +(1-ρ)q in the infinite size limit. We believe this settles in the negative the suggestion made [S. Galam and A. C. R. Martins, Europhys. Lett. 95, 48005 (2001), 10.1209/0295-5075/95/48005] that this result would be a finite size effect, with the exit probability actually being a step function. We also show how the result that the exit probability cannot be a step function can be reconciled with the Galam unified frame, which was also a source of controversy.

  11. 78 FR 76054 - Establishment of Class E Airspace; Chatom, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-16

    ..., Georgia 30320; telephone (404) 305-6364. ] SUPPLEMENTARY INFORMATION: History On September 4, 2013, the... Above the Surface of the Earth. * * * * * ASO AL E5 Chatom, AL Roy Wilcox Airport, AL (Lat. 31 27'06''...

  12. [Al-Biruni--a universal scientist].

    PubMed

    Kujundzić, E; Masić, I

    1999-01-01

    Al-Biruni's was of Persian descent. He was born in Horesmiya and had studied mathematics, history and medicine. Acquiring knowledge from these sciences, he wrote an outstanding work on chronology of several nations and devoted it to Ziyarit ruler Kabus. He made a chronological overview of calendars from many nations, including Persians, Greeks, Egyptians, Jews, Melkitian and Nestorian Christians, Sabeyaans as well as the old Arabs. Data presented in the work, according to the later authors, were taken from very reliable sources. He was contemporary of Ibn-Sina, and thanks to their friendship, they have discussed very much miscellaneous topics. He belonged to the group of scholars, taken by Gaznevian Soultan Mahmud to a long journey to India. Afterwards Al-Biruni wrote and published detailed work "Description of India"--a work on cultural history of India. Due to excellent abilities of Al-Biruni as a philosopher and scholar, there are still significant and reliable notes about buddhistic philosophy, structure of castes and Brahmans' life style. In this Al-Biruni's masterpiece, there are many comparative analysis of Suffism and certain Indian philosophical methods. Al-Biruni's most important work is "Pharmacopoeia"--"Kitab al-saydala", which brilliantly describes all medicaments. This work has been published in many languages. He also wrote few works on astronomy and astrology. In those works he has explained some astrological events through scientific approach in a such peculiar way that nobody has ever explained before. He was also interested in sciences like geology, mineralology, geography, mathematics, psychology and many others.

  13. Al Sahawa - The Awakening: An Education and Training Resource Guide

    DTIC Science & Technology

    2015-07-01

    Mamoun Sami Rashid , Al Anbar Governor during 2005–06 described it best as a sequence of actions and events throughout Al Anbar: When we started... Rashid , Al Anbar Governor 2005 to 2006, interview with Dr. William Knarr, Colonel Dale Alford, USMC, and Lieutenant Colonel David Graves, USMC...1 . Who’s Who Appendix A Interviewees Abd al-Hakim Muhammad Rashid Muhammad al-Jughayfi, Mayor of Hadithah Abdul Qadir Mohammed Jassim Obeidi al

  14. A Comment on Eerland et al. (2016).

    PubMed

    Hart, William

    2016-03-01

    People imagine criminal behavior in greater detail and ascribe more blame to criminals when a description of a crime is written using the imperfective verb aspect (Hart & Albarracín, 2011, Experiment 3). An initiative to reproduce these findings conducted by Eerland et al. (2016) yielded a lack of replication. Eerland et al. have suggested that the original effect was likely driven by a Type I error produced by methodological aspects of the experiment, including low sample size. Recent conceptual replications of Hart and Albarracín's effect (Sherrill, Eerland, Zwaan, & Magliano, 2015), however, might imply the effect could be contingent on sample characteristics.

  15. Vibrations on Al surfaces covered by sodium

    NASA Astrophysics Data System (ADS)

    Rusina, G. G.; Eremeev, S. V.; Borisova, S. D.; Sklyadneva, I. Yu.; Chulkov, E. V.

    2006-09-01

    In this paper we present the results of a comparative study of vibrational and structural properties of the ordered (√{3}×√{3})R30∘ and c(2 × 2) phases formed by Na adatoms at room temperature on the Al(1 1 1) and Al(1 0 0) surfaces, respectively. The surface relaxation, surface phonon dispersion, and polarization of vibrational modes are calculated using the embedded-atom method. Our calculated structural parameters are in agreement with experimental and ab initio results. The obtained vibrational frequencies compare fairly well with available experimental data.

  16. Complementary and Alternative Therapies in ALS

    PubMed Central

    Bedlack, Richard S.; Joyce, Nanette; Carter, Gregory T.; Pagononi, Sabrina; Karam, Chafic

    2015-01-01

    Synopsis Given the severity of their illness and lack of effective disease modifying agents, it is not surprising that most patients with ALS consider trying complementary and alternative therapies. Some of the most commonly considered alternative therapies include special diets, nutritional supplements, cannabis, acupuncture, chelation and energy healing. This chapter reviews these in detail. We also describe 3 models by which physicians may frame discussions about alternative therapies: paternalism, autonomy and shared decision making. Finally, we review a program called ALSUntangled which using shared shared decision making to review alternative therapies for ALS. PMID:26515629

  17. The Future of Al Qa’ida

    DTIC Science & Technology

    2011-05-24

    commissions and panels; and private review and oversight bodies. C O R P O R A T I O N For More Information Visit RAND at www.rand.org Explore RAND...affiliated groups and its leadership. A range of senior officials, including Saif al-Adel and Abu Miqad al-Masri, continue to play key roles. Finally, there...20 30 40 50 60 70 2003 2005 2006 2007 2008 2009 2010 Turkey Egypt Jordan Lebanon Indonesia Pakistan Pe rc te nt ag e  of   R es po nd en ts  w it h  Co

  18. Heterogeneity of Mg Isotopes and Variable ^26Al/^27Al Ratio in FUN CAIs

    NASA Astrophysics Data System (ADS)

    Park, C.; Nagashima, K.; Hutcheon, I. D.; Wasserburg, G. J.; Papanastassiou, D. A.; Davis, A. M.; Huss, G. R.; Krot, A. N.

    2013-09-01

    We report high-precision Mg-isotope data of individual minerals from the Axtell 2271, BG82DH8, EK1-4-1, C1, TE, and CG14 FUN CAIs, which shows variations in both Mg-isotope ratio and ^26Al/^27Al ratio.

  19. Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.

  20. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    DOEpatents

    Deevi, Seetharama C.; Sikka, Vinod K.

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  1. An Alternative Perspective on von Winterfeldt et al.'s (1997) Test of Consequence Monotonicity

    ERIC Educational Resources Information Center

    Ho, Moon-Ho R.; Regenwetter, Michel; Niederee, Reinhard; Heyer, Dieter

    2005-01-01

    D. von Winterfeldt, N.-K. Chung, R. D. Luce, and Y. Cho (see record 1997-03378-008) provided several tests for consequence monotonicity of choice or judgment, using certainty equivalents of gambles. The authors reaxiomatized consequence monotonicity in a probabilistic framework and reanalyzed von Winterfeldt et al.'s main experiment via a…

  2. Transport mechanisms of leakage current in Al2O3/InAlAs MOS capacitors

    NASA Astrophysics Data System (ADS)

    Jin, Chengji; Lu, Hongliang; Zhang, Yimen; Zhang, Yuming; Guan, He; Wu, Lifan; Lu, Bin; Liu, Chen

    2016-09-01

    An Al2O3 layer is inserted between the InAlAs layer and the metal gate in InAs/AlSb HEMTs to suppress the leakage current. The transport mechanisms of leakage current in Al2O3/InAlAs metal-oxide-semiconductor (MOS) capacitors at both positive and negative biases at different temperatures ranging from 10 °C to 70 °C are investigated. For positive bias, the leakage current is dominated by Schottky emission. Based on the fitted straight lines, the relative dielectric constant of Al2O3 and the barrier height between Al2O3 and InAlAs are extracted. However, for negative bias, the leakage current is dominated by Frenkel-Poole (F-P) emission and the depth of the trap energy level from the conduction band (ϕt) is extracted. Furthermore, authors explain the reason why the dominating mechanisms at positive and negative biases are different.

  3. The Genyornis Egg: Response to Miller et al.'s commentary on Grellet-Tinner et al., 2016

    NASA Astrophysics Data System (ADS)

    Grellet-Tinner, Gerald; Spooner, Nigel A.; Handley, Warren D.; Worthy, Trevor H.

    2017-04-01

    Williams (1981) and Williams and Rich (1991) attributed Australian Quaternary fossil eggshell that differed from that of emu Dromaius novaehollandiae to the extinct bird Genyornis newtoni without any osteological or embryonic support. Such association by proximity or abundance mirrors the case of the mistaken association of oviraptor eggs to Protoceratops in the 1920's by Andrews (Grellet-Tinner and Makovicky, 2006). No other candidate species was considered, and this attribution has been unchallenged and followed by everyone thereafter. Much research has been done on this Australian eggshell, with one result being that the extinction of the parent of this eggshell is the most well documented for a taxon in Australia (e.g., Miller et al., 1999, 2005). Grellet-Tinner et al. (2016) raised several problems with the identity of the eggshell Williams (1981) attributed to Genyornis newtoni and suggested that extinct megapodes of the genus Progura were the more likely layer of this eggshell type, therein referred to as ;putative Genyornis oological material; (PGOM). Miller et al. (2017) challenged our hypothesis stating that ;Based on the dimensions of the reconstructed Spooner Egg,Grellet-Tinner et al. (2016)argue that PGOM is too small for a bird with the body mass estimated for Genyornis (168-275 kg) … …[and] …. None of the additional PGOM observations reported byGrellet-Tinner et al. (2016)are inconsistent with a Genyornis parent;. Here we take the opportunity to respond to their critique, the basis of which resolves into a few points, which we address in turn.

  4. An impedance study of complex Al/Cu-Al2O3 electrode

    NASA Astrophysics Data System (ADS)

    Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.

    2011-06-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

  5. Fundamental Influence of C on Adhesion of the Al2O3/Al Interface

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Smith, John R.; Evans, Anthony

    2002-12-01

    Our first-principles computations indicate that the clean Al2O3/Al interface is relatively weak—weaker than bulk Al. Fracture experiments reveal that the interface is relatively strong with observed failure in bulk Al, however. This paradox is resolved via doping effects of the common impurity C. We have found that only 1/3 of a monolayer of carbon segregated to the interface can increase the work of separation by a factor of 3. The resulting strong interface is consistent with fracture experiments. It arises due to void formation in the interface, which provides low-strain sites for the carbon to segregate to. The degree of void formation is consistent with the relatively high heat of oxide formation of Al.

  6. CVD Fiber Coatings for Al2O3/NiAl Composites

    NASA Technical Reports Server (NTRS)

    Boss, Daniel E.

    1995-01-01

    While sapphire-fiber-reinforced nickel aluminide (Al2O3/NiAl) composites are an attractive candidate for high-temperature structures, the significant difference in the coefficient of thermal expansion between the NiAl matrix and the sapphire fiber creates substantial residual stresses in the composite. This study seeks to produce two fiber-coating systems with the potential to reduce the residual stresses in the sapphire/NiAl composite system. Chemical vapor deposition (CVD) was used to produce both the compensating and compliant-fiber coatings for use in sapphire/NiAl composites. A special reactor was designed and built to produce the FGM and to handle the toxic nickel precursors. This process was successfully used to produce 500-foot lengths of fiber with coating thicknesses of approximately 3 microns, 5 microns, and 10 microns.

  7. Temperature dependence of the activity of Al in dilute Ni(Al) solid solutions

    SciTech Connect

    Jiang Yong; Smith, J. R.; Evans, A. G.

    2006-12-01

    Activities of dilute Al solid solutions in Ni are determined from a first-principles approach. Both thermal lattice vibration and electronic contributions to free energies are considered and compared. Vibrational contributions tend to dominate the temperature dependencies of the free energies, though electron thermal effects are significant. Calculations show opposing temperature trends for the formation enthalpies and entropies, leading to a partial cancellation of their role in the overall energetics. Nevertheless, their remaining temperature effects are strong. Over the temperature range, 400 KAl activity coefficient varies by 15 orders of magnitude, due to the relative strength of Al-Ni and Al-Al bonds. The Ni activity coefficient only varies less than 4% over the same range. Calculational results compare well with available experimental data. The thermodynamic principles elucidated from the calculations are used to provide a fundamental interpretation.

  8. Al/sub 2/O/sub 3/ adherence on CoCrAl alloys

    SciTech Connect

    Kingsley, L.M.

    1980-04-01

    Adherence of protective oxides on NiCrAl and CoCrAl superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of Al/sub 2/O/sub 3/ as both the dispersion and protective oxide; and the production of an HfO/sub 2/ dispersion while simultaneously aluminizing the alloy. It was found that an Al/sub 2/O/sub 3/ dispersion will act to promote the adherence of an external scale of Al/sub 2/O/sub 3/ to a degree comparable to previously tested dispersions and an HfO/sub 2/ dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization.

  9. 1300 K compressive properties of a reaction milled NiAl-AlN composites

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Arzt, Eduard; Luton, Michael J.

    1990-01-01

    When B2 crystal-structure nickel aluminide is subjected to high-intensity mechanical ball milling in a liquid nitrogen bath, or 'cryomilling', an NiAl composite is obtained which contains about 10 vol pct AlN particles. This composition arises from the incorporation of N during cryomilling; during subsequent thermomechanical processing, the N reacts with Al. While compressive testing of extruded or isostatically pressed specimens at 1300 K indicated that strength at relatively fast strain rates is slightly dependent on consolidation method, slower strain rates indicate no clear dependency on densification technique: four different consolidation methods were found to yield similar creep strengths. The creep properties of NiAl-AlN are similar to those of the single-crystal Ni-base superalloy NASAIR 100.

  10. Bonding characters of Al-containing bulk metallic glasses studied by 27Al NMR.

    PubMed

    Xi, X K; Sandor, M T; Wang, H J; Wang, J Q; Wang, W H; Wu, Y

    2011-03-23

    We report very small (27)Al metallic shifts in a series of Cu-Zr-Al bulk metallic glasses. This observation and the Korringa type of spin-lattice relaxation behavior suggest that s-character wavefunctions weakly participate in bonding and opens the possibility of enhanced covalency (pd hybridization) with increasing Al concentration, in good agreement with elastic constants and hardness measurements. Moreover, ab initio calculations show that this bonding character originates from the strong Al 3p band and Zr 4d band hybridization since their atomic energy levels are closer to each other while the Al 3s band is localized far below the Fermi level. This study might provide a chemical view for understanding flow and fracture mechanisms of these bulk glass-forming alloys.

  11. The Si/Si_3N4 Interface and Si/Si_3N4 Submicron Mesa: A Multi-million Atom Molecular Dynamics Study

    NASA Astrophysics Data System (ADS)

    Bachlechner, Martina E.; Omeltchenko, Andrey; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya; Ebbsjö, Ingvar; Madhukar, Anupam

    1998-03-01

    Using molecular dynamics simulations on parallel computers, the interface structure, stress distribution, crack propagation and fracture in a Si_3N4 film on Si substrate are studied. Bulk Si is described by Stillinger-Weber potential and Si_3N4 is represented by a combination of two- and three-body covalent interactions. At the interface, the charge transfer is taken from LCAO electronic structure calculations (G.-L. Zhao and M.E. Bachlechner, Europhys. Lett. 36, 287 (1997)). Results for structural correlations at the interface and 3D stress distribution for the submicron mesa are presented.

  12. Detection and manipulation of sychronization processes during depth electrode implantation

    NASA Astrophysics Data System (ADS)

    Schiek, Michael; Zimmermann, Egon; Freund, Hans-Joachim; Sturm, Volker; Tass, Peter

    2002-03-01

    Population of phase oscillators can effectively be desynchronized with composite stimulation techniques using stochastic phase resetting principles [1]. This approach is used to design the first model-based demand controlled deep brain stimulation techniques for the therapy of neurological diseases like Parkinson's disease. We report on first tests of these novel techniques performed in patients during electrode implantation. [1] P.A. Tass: Europhys.Lett. 53(2001) 15-21; 55(2001) 171-177; Biol. Cybern. 85(2001) 343-354

  13. Statistical analysis of financial returns for a multiagent order book model of asset trading

    NASA Astrophysics Data System (ADS)

    Preis, Tobias; Golke, Sebastian; Paul, Wolfgang; Schneider, Johannes J.

    2007-07-01

    We recently introduced a realistic order book model [T. Preis , Europhys. Lett. 75, 510 (2006)] which is able to generate the stylized facts of financial markets. We analyze this model in detail, explain the consequences of the use of different groups of traders, and focus on the foundation of a nontrivial Hurst exponent based on the introduction of a market trend. Our order book model supports the theoretical argument that a nontrivial Hurst exponent implies not necessarily long-term correlations. A coupling of the order placement depth to the market trend can produce fat tails, which can be described by a truncated Lévy distribution.

  14. Onsager coefficients of a Brownian Carnot cycle

    NASA Astrophysics Data System (ADS)

    Izumida, Y.; Okuda, K.

    2010-10-01

    We study a Brownian Carnot cycle introduced by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] from a viewpoint of the linear irreversible thermodynamics. By considering the entropy production rate of this cycle, we can determine thermodynamic forces and fluxes of the cycle and calculate the Onsager coefficients for general protocols, that is, arbitrary schedules to change the potential confining the Brownian particle. We show that these Onsager coefficients contain the information of the protocol shape and they satisfy the tight-coupling condition irrespective of whatever protocol shape we choose. These properties may give an explanation why the Curzon-Ahlborn efficiency often appears in the finite-time heat engines.

  15. A first order Tsallis theory

    NASA Astrophysics Data System (ADS)

    Ferri, Gustavo L.; Plastino, Angel; Rocca, Mario C.; Zamora, Dario J.

    2017-03-01

    We investigate first-order approximations to both (i) Tsallis' entropy Sq and (ii) the Sq-MaxEnt solution (called q-exponential functions eq). We use an approximation/expansion for q very close to unity. It is shown that the functions arising from the procedure (ii) are the MaxEnt solutions to the entropy emerging from (i). Our present treatment is motivated by the fact it is FREE of the poles that, for classic quadratic Hamiltonians, appear in Tsallis' approach, as demonstrated in [A. Plastimo, M.C. Rocca, Europhys. Lett. 104, 60003 (2013)]. Additionally, we show that our treatment is compatible with extant date on the ozone layer.

  16. Reaction and fusion cross sections for the near-symmetric system 129Xe+natSn from 8 A to 35 A MeV

    NASA Astrophysics Data System (ADS)

    Manduci, L.; Lopez, O.; Chbihi, A.; Rivet, M. F.; Bougault, R.; Frankland, J. D.; Borderie, B.; Galichet, E.; La Commara, M.; Le Neindre, N.; Lombardo, I.; Pârlog, M.; Rosato, E.; Roy, R.; Verde, G.; Vient, E.; Indra Collaboration

    2016-10-01

    Background: We study heavy-ion reactions from barrier up to Fermi energy. The data were acquired with the INDRA detector at the GANIL (Caen, France) facility. Purpose: We aim to determine the reaction and fusion cross sections for the reactions induced by 129Xe projectiles on natSn targets for incident energies ranging from 8 A to 35 A MeV. In particular, the evaluation of the fusion and incomplete fusion cross sections is the main purpose, altogether with the comparison with the systematics of Eudes et al. [Europhys. Lett. 104, 22001 (2013), 10.1209/0295-5075/104/22001]. Method: The reaction cross sections are evaluated at each beam energy with data acquired thanks to the INDRA 4 π array. The events are sorted with the help of the observable Eiso,max. We focus therefore our study on a selected sample of events, in such a way that the fusion and incomplete fusion cross sections can be estimated. Results: We present the excitation function of reaction and fusion cross sections for the heavy and nearly symmetric system 129Xe+natSn from 8 A to 35 A MeV. For the fusion excitation function the comparison with the systematics of Eudes et al. seems to be in a fair agreement starting from the beam energy 20 A MeV. For the lower beam energies (8 A and 12 A MeV) discrepancies are observed. Conclusions: The evaluated fusionlike cross sections show a good agrement with a recent systematics for beam energies greater than 20 A MeV. For low beam energies the cross-sectional values are lower than the expected ones. A probable reason for these low values is in the fusion hindrance at energies above or close to the barrier.

  17. Absolute Total Cross Section Measurements for Electron Scattering on GeH4 and SiH4 Molecules

    NASA Astrophysics Data System (ADS)

    Zejko, Pawel. Mo.; Kasperski, Grzegorz; Szmytkowski, Czeslaw

    1996-10-01

    We have measured absolute grand total electron--scattering cross section for GeH4 and SiH4 molecules in the energy range of 0.75--250 eV and 0.6--250 eV, respectively, using the linear transmission experimental setup(A.M. Krzysztofowicz and Cz. Szmytkowski 1995 J. Phys. B 28) 1593. The general character of both obtained total cross section (TCS) functions is similar. For germane TCS dramatically increases from 12× 10-20 m^2 at 0.8 eV up to nearly 59× 10-20 m^2 at the 3.8 eV maximum. For silane the maximum (57× 10-20 m^2) is localized near 2.9 eV. These structures are partly attributable to the existence of short-lived negative-ion resonant states. From 10 eV to the highest applied energy TCS' decrease monotonically with increasing impact energy E, and above 50 eV the total cross sections change like E-0.5. None low-energy e^--GeH4 experiment is available for comparison. Above 75 eV our results are in good agreement with the recent intermediate-energy TCS measurements of Karwasz(G.P. Karwasz 1995 J. Phys. B 28) 1301 and with calculations of Baluja et al(K.L. Baluja et al) 1992 Europhys. Lett. 17 139. There is also reasonably agreement of present e^--SiH4 data with available experimental results.

  18. Evolution of quasiparticle states with and without a Zn impurity in doped 122 iron pnictides

    NASA Astrophysics Data System (ADS)

    Pan, Lihua; Li, Jian; Tai, Yuan-Yen; Graf, Matthias J.; Zhu, Jian-Xin; Ting, C. S.

    2014-10-01

    Based on a minimal two-orbital model [Tai et al., Europhys. Lett. 103, 67001 (2013), 10.1209/0295-5075/103/67001], which captures the canonical electron-hole-doping phase diagram of the iron-pnictide BaFe2As2, we study the evolution of quasiparticle states as a function of doping using the Bogoliubov-de Gennes equations with and without a single impurity. Analyzing the density of states of uniformly doped samples, we are able to identify the origin of the two superconducting gaps observed in optimally hole- or electron-doped systems. The local density of states (LDOS) is then examined near a single impurity in samples without antiferromagnetic order. The qualitative features of our results near the single impurity are consistent with a work based on a five-orbital model [T. Kariyado et al., J. Phys. Soc. Jpn. 79, 083704 (2010), 10.1143/JPSJ.79.083704]. Some of the results are consistent with recent angle-resolved photoemission spectroscopy and scanning tunneling spectroscopy experiments. This further supports the validity of our two-orbital model in dealing with LDOS in the single-impurity problem. Finally, we investigate the evolution of the LDOS with doping near a single impurity in the unitary or strong scattering limit, such as Zn replacing Fe. The positions of the in-gap resonance peaks exhibited in our LDOS may indirectly reflect the evolution of the Fermi surface topology according to the phase diagram. Our prediction of in-gap states and the evolution of the LDOS near a strong scattering single impurity can be validated by further experiments probing the local quasiparticle spectrum.

  19. Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

  20. Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

  1. 76 FR 62481 - Incapital LLC, et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-07

    ... From the Federal Register Online via the Government Publishing Office SECURITIES AND EXCHANGE COMMISSION Incapital LLC, et al.; Notice of Application September 30, 2011. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of application for an order under section 12(d)(1)(J) of...

  2. Electron impact exctation of Al X

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti; Keenan, Francis

    2013-05-01

    Emission lines of Al ions, including Al X, are important for the modeling and diagnostics of lasing, fusion and astrophysical plasmas, for which atomic data are required for a variety of parameters, such as energy levels, radiative rates (A- values), and excitation rates or equivalently the effective collision strengths (Υ), which are obtained from the electron impact collision strengths (Ω). Experimentally, energy levels are available for Al X on the NIST website, but there is paucity for accurate collisional atomic data. Therefore, here we report a complete set of results (namely energy levels, radiative rates, and effective collision strengths) for all transitions among the lowest 98 levels of Al X. These levels belong to the (1s2) 2s2, 2s2p, 2p2, 2s3 l, 2p3 l, 2s4 l, and 2p4 l configurations. Finally, we also report the A- values for four types of transitions, namely electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2), because these are also required for plasma modeling. For our calculations of wavefunctions, we have adopted the fully relativistic GRASP code, and for the calculations of Ω, the Dirac atomic R-matrix code (DARC) of PH Norrington and IP Grant. Additionally, parallel ca

  3. Kinematics of Disease Progression in Bulbar ALS

    ERIC Educational Resources Information Center

    Yunusova, Yana; Green, Jordan R.; Lindstrom, Mary J.; Ball, Laura J.; Pattee, Gary L.; Zinman, Lorne

    2010-01-01

    The goal of this study was to investigate the deterioration of lip and jaw movements during speech longitudinally in three individuals diagnosed with bulbar amyotrophic lateral sclerosis (ALS). The study was motivated by the need to understand the relationship between physiologic changes in speech movements and clinical measures of speech…

  4. U-ALS: A Ubiquitous Learning Environment

    ERIC Educational Resources Information Center

    Piovesan, Sandra Dutra; Passerino, Liliana Maria; Medina, Roseclea Duarte

    2012-01-01

    The diffusion of the use of the learning virtual environments presents a great potential for the development of an application which meet the necessities in the education area. In view of the importance of a more dynamic application and that can adapt itself continuously to the students' necessities, the "U-ALS" (Ubiquitous Adapted Learning…

  5. 75 FR 1420 - Alabama Disaster # AL-00025

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-11

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00025 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  6. 78 FR 4967 - Alabama Disaster #AL-00046

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00046 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of ALABAMA dated...

  7. 76 FR 29810 - Alabama Disaster #AL-00037

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-23

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00037 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for...

  8. 75 FR 474 - Alabama Disaster #AL-00026

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-05

    ... [Federal Register Volume 75, Number 2 (Tuesday, January 5, 2010)] [Notices] [Pages 474-475] [FR Doc No: E9-31259] SMALL BUSINESS ADMINISTRATION [Disaster Declaration 11988 and 11989] Alabama Disaster AL-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice...

  9. 78 FR 26100 - Alabama Disaster #AL-00050

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-03

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00050 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  10. 76 FR 27141 - Alabama Disaster # AL-00036

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00036 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Alabama...

  11. 77 FR 7227 - Alabama Disaster #AL-00040

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-10

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00040 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for the State of Alabama...

  12. 75 FR 26814 - Alabama Disaster #AL-00031

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ... [Federal Register Volume 75, Number 91 (Wednesday, May 12, 2010)] [Notices] [Pages 26814-26815] [FR Doc No: 2010-11201] SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12157 and 12158] Alabama Disaster AL-00031 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice...

  13. 78 FR 22361 - Alabama Disaster #AL-00049

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-15

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION Alabama Disaster AL-00049 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Alabama dated...

  14. 75 FR 26813 - Alabama Disaster #AL-00029

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-12

    ... [Federal Register Volume 75, Number 91 (Wednesday, May 12, 2010)] [Notices] [Pages 26813-26814] [FR Doc No: 2010-11199] SMALL BUSINESS ADMINISTRATION [Disaster Declaration 12155 and 12156] Alabama Disaster AL-00029 AGENCY: Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of...

  15. 76 FR 35938 - The Designation of Othman al-Ghamdi Also Known as Al Umairah al-Ghamdi, Also Known as Uthman al...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... [Federal Register Volume 76, Number 118 (Monday, June 20, 2011)] [Notices] [Page 35938] [FR Doc No: 2011-15290] DEPARTMENT OF STATE [Public Notice 7505] The Designation of Othman al-Ghamdi Also Known as... the Federal Register. Dated: May 11, 2011. Hillary Rodham Clinton, Secretary of State. [FR Doc....

  16. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

  17. Hughes et al.: Science or Promotion?

    ERIC Educational Resources Information Center

    Loman, L. Anthony; Siegel, Gary L.

    2013-01-01

    The Hughes et al. paper is critiqued generally and in specific areas. The weak nature of the authors' empirical work is discussed along with their enigmatic writing and vague and incorrect use of references, and their simultaneous use of sweeping statements of opinion and narrow analytical focus. This review examines the authors' errors…

  18. Cryptanalysis on Cheng et al. protocol

    NASA Astrophysics Data System (ADS)

    Thakur, Tejeshwari

    2016-06-01

    Deployment of new node in any wireless sensor network is a sensitive task. This is the reason why, an Access Control Protocol is required in WSN. In this paper, we demonstrate that Access Control Protocol proposed by Cheng et al.[1] for Wireless Sensor Network is insecure. The reason is that this protocol fails to resist the active attack.

  19. Al-Qaida: Terrorist Selection and Recruitment

    DTIC Science & Technology

    2006-01-01

    like them, not alien outsiders. 9. Surrounding potential recruits with peers who are already established recruits. 10. E. Goffman , Behavior in Public...Cultic Studies Journal 1:2 (1984): 167–177. 88 SECTION 1 Al-Qaida and Global Jihad Goffman , E., Behavior in Public Places: Notes on the Social

  20. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-07-25

    A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.

  1. Al/Cl2 molten salt battery

    NASA Technical Reports Server (NTRS)

    Giner, J.

    1972-01-01

    Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of AlCl3, NaCl, and some alkali metal halide such as KCl.

  2. Magnetic structures and excitations in a multiferroic Y-type hexaferrite BaSrCo2Fe11AlO22

    NASA Astrophysics Data System (ADS)

    Nakajima, Taro; Tokunaga, Yusuke; Matsuda, Masaaki; Dissanayake, Sachith; Fernandez-Baca, Jaime; Kakurai, Kazuhisa; Taguchi, Yasujiro; Tokura, Yoshinori; Arima, Taka-hisa

    2016-11-01

    We have investigated magnetic orders and excitations in a Y-type hexaferrite BaSrCo2Fe11AlO22 (BSCoFAO), which was reported to exhibit spin-driven ferroelectricity at room temperature [S. Hirose, K. Haruki, A. Ando, and T. Kimura, Appl. Phys. Lett. 104, 022907 (2014), 10.1063/1.4862432]. By means of magnetization, electric polarization, and neutron-diffraction measurements using single-crystal samples, we establish a H -T magnetic phase diagram for magnetic field perpendicular to the c axis (H⊥c). This system exhibits an alternating longitudinal conical (ALC) magnetic structure in the ground state, and it turns into a non-co-planar commensurate magnetic order with spin-driven ferroelectricity under H⊥c. The field-induced ferroelectric phase remains as a metastable state after removing magnetic field below ˜250 K. This metastability is the key to understanding of magnetic field reversal of the spin-driven electric polarization in this system. Inelastic polarized neutron-scattering measurements in the ALC phase reveal a magnetic excitation at around 7.5 meV, which is attributed to spin components oscillating in a plane perpendicular to the cone axis. This phasonlike excitation is expected to be an electric-field active magnon, i.e., electromagnon excitation, in terms of the magnetostriction mechanism.

  3. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, J.; Gibala, R.

    1979-01-01

    The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids were observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. The voids resulted from an excess number of oxygen vacancies near the oxidemetal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidation of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al, Cr)2O3 and Ni(Al, Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationship between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

  4. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, J.; Gibala, R.

    1979-01-01

    The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids have been observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. It was postulated that the voids resulted from an excess number of oxygen vacancies near the oxide-metal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidations of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al,Cr)2O3 and Ni(Al,Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationships between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

  5. AlGaN/AlN integrated photonics platform for the ultraviolet and visible spectral range.

    PubMed

    Soltani, Mohammad; Soref, Richard; Palacios, Tomas; Englund, Dirk

    2016-10-31

    We analyze a photonic integrated circuit (PIC) platform comprised of a crystalline AlxGa1-xN optical guiding layer on an AlN substrate for the ultraviolet to visible (UV-vis) wavelength range. An Al composition of x~0.65 provides a refractive index difference of ~0.1 between AlxGa1-xN and AlN, and a small lattice mismatch (< 1%) that minimizes crystal dislocations at the AlxGa1-xN/AlN interface. This small refractive index difference is beneficial at shorter wavelengths to avoid extra-small waveguide dimensions. The platform enables compact waveguides and bends with high field confinement in the wavelength range from 700 nm down to 300 nm (and potentially lower) with waveguide cross-section dimensions comparable to those used for telecom PICs such as silicon and silicon nitride waveguides, allowing for well-established optical lithography. This platform can potentially enable cost-effective, manufacturable, monolithic UV-vis photonic integrated circuits.

  6. A novel Al matrix composite reinforced by nano-AlNp network

    PubMed Central

    Ma, X.; Zhao, Y. F.; Tian, W. J.; Qian, Z.; Chen, H. W.; Wu, Y. Y.; Liu, X. F.

    2016-01-01

    In pursuit of lightweighting of automobiles and low emission of transportation, the efforts to develop high-strength, heat-resistant and fatigue-resistant Al alloys and/or composites have been ongoing. Here we report a novel Al matrix composite with ultrahigh strength reinforced by a three dimensional network of nano-AlN particles for the first time. The in-situ synthesized AlN particles are connected by twinning bonding chains and built up a three dimensional network strengthening Al matrix enormously like the skeleton to human body. The composite containing 16.4wt.% AlN particles shows excellent properties: the ultimate tensile strengths can be up to 518MPa at room temperature and 190MPa at 350 °C. This peculiar performance results from the novel spatial distribution of nano-scale AlN particles. Our findings in this work would help to develop a potential candidate for high-performance heat resistance light-metal based materials. PMID:27721417

  7. Effect of speciation transformation on the coagulation behavior of Al(13) and Al(13) aggregates.

    PubMed

    Wu, Xiaohong; Ye, Changqing; Wang, Dongsheng; Ge, Xiaopeng; Tang, Hongxiao

    2009-01-01

    Flocculation of kaolin suspension with aluminium fractal polycations was investigated as a function of aluminium concentration and pH. Aluminium flocculants included Al(13) and Al(13) aggregates with OH/Al ratio of 2.6 and 2.8, respectively. The flocculation kinetics and floc size distribution were monitored by light scattering. The characterization of flocculants showed that the tridecatmer Al(13) and bridged [Al(13)](n) with out-sphere structure were the dominant species for all flocculants in a wide pH range. The coagulation results indicated that the pre and in situ-formed [Al(13)](n) play a key role in removing particles. With the increasing concentration of [Al(13)](n), coagulation mechanisms were transformed from charge-neutralization, electro-patch coagulation to bridge-aggregation. Moreover, sweep-flocculation was involved at higher dosage besides other three mechanisms when amorphous aluminium oxides formed. Hence, chemical interaction between particles and flocculants evolved from surface adsorption to surface precipitation for aluminium polycations by virtue of species transformation.

  8. Wetting of polycrystalline SiC by molten Al and Al-Si alloys

    NASA Astrophysics Data System (ADS)

    Cong, Xiao-Shuang; Shen, Ping; Wang, Yi; Jiang, Qichuan

    2014-10-01

    The wetting of α-SiC by molten Al and Al-Si alloys was investigated using a dispensed sessile drop method in a high vacuum. In the Al-SiC system, representative wetting stages were identified. The liquid spreading was initially controlled by the deoxidation of the SiC surface and then by the formation of Al4C3 at the interface. The intrinsic contact angle for molten Al on the polycrystalline α-SiC surface was suggested to be lower than 90̊ provided that the oxide films covering the Al and SiC surfaces were removed, i.e., the system is partial wetting in nature. An increase in the Si concentration in liquid Al weakened the interfacial reaction but improved the final wettability. The role of the Si addition on the wetting was presumably attributed to its segregation at the interface and the formation of strong chemical bonds with the SiC surface.

  9. High-pressure phase relations in the composition of albite NaAlSi3O8 constrained by an ab initio and quasi-harmonic Debye model, and their implications

    NASA Astrophysics Data System (ADS)

    Deng, L.; Liu, X.; Liu, H.; Dong, J.

    2010-12-01

    phase assemblage transforms into the CS phase assemblage at about 33.6 GPa at 0 K, and the Clayperon slope of this phase transition is about 0.014 GPa/K. This study implies that lingunite (Na-Holl), found in somemeteorites, is not possibly a thermodynamically stable high-P phase, and the Cf phase probably plays an important role in maintaining the sodium budget and hosting the large-ion lithophile elements in the deep interior of the Earth. References: Beck, P., Gillet, P., Gautron, L., Daniel, I., El Goresy, A., 2004. A new natural high-pressure (Na, Ca)-hexaluminosilicate [(CaxNa1-x)Al3+xSi3-xO11] in shocked Martian meteorites. Earth Planet. Sci. Lett. 219, 1-12. Liu, L., 1978. High-pressure phase transformations of albite, jadeite and nepheline. Earth Planet. Sci. Lett. 37, 438-444. Sekine, T., Ahrens, T.J., 1992. Shock-induced transformations in the system NaAlSi3O8-SiO2: a new interpretation. Phys. Chem. Mineral. 18, 359-364. Tutti, F., 2007. Formation of end-member NaAlSi3O8 hollandite-type structure (lingunite) in diamond anvil cell. Phys. Earth Planet. Inter. 161, 143-149.

  10. Investigation of water assisted phase transformation process from AlPO4-5 to AlPO4-tridymite

    SciTech Connect

    Xu, Suochang; Zhao, Zhenchao; Hu, Mary Y.; Han, Xiuwen; Hu, Jian Zhi; Bao, Xinhe

    2016-03-01

    Water assisted phase transformation process from crystalized AlPO4-5 to AlPO4-tridymite was studied by the combination of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and in situ multinuclear MAS NMR. It is found that water first activates the residue amorphous aluminophosphate in crystalized AlPO4-5 sample through hydrolysis and condensation reactions. Then the activated aluminophosphate species reassemble into AlPO4-tridymite crystalline. Meanwhile, AlPO4-5 transforms into orthorhombic phase during heating process. With further crystallization of AlPO4-tridymite, the amorphous phase is gradually consumed, and mass transportation between AlPO4-5 and AlPO4-tridymite is established through gradually amorphization of AlPO4-5. Finally, most of the AlPO4-5 transforms into the thermodynamically stable dense phase AlPO4-tridymite.

  11. Aluminum matrix texture in Al-Al3Ti functionally graded materials analyzed by electron back-scattering diffraction

    NASA Astrophysics Data System (ADS)

    Watanabe, Yoshimi; Sequeira, Paulo D.; Sato, Hisashi; Inamura, Tomonari; Hosoda, Hideki

    2016-01-01

    Al matrix functionally graded materials (FGMs) with oriented Al3Ti platelets were fabricated by a centrifugal solid-particle method. The applied centrifugal forces were 30, 60, and 120G (units of gravity). The orientation and volume fraction gradients of the Al3Ti platelets within the samples were measured. Since a good lattice correspondence was reported for the close-packed directions and the close-packed planes between Al and Al3Ti, the Al matrix in the Al-Al3Ti FGMs fabricated by the centrifugal solid-particle method should have some texture. Al matrix texture was, therefore, analyzed by electron back-scattering diffraction (EBSD). Analysis of the resulting pole figures indicates a preferred orientation along the (200) plane for the Al matrix crystals. Furthermore, increasing the applied centrifugal force enhances the orientation effect. A correlation appears to exist between platelet orientation and the preferred texture of the Al matrix.

  12. An Epidemiological Study of Cutaneous Leishmaniasis in Al-Jabal Al-Gharbi, Libya

    PubMed Central

    Abdellatif, Manal Z. M.; El-Mabrouk, Khamis

    2013-01-01

    Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and its Al-jabal Al-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more affected than younger ones (P=0.0001). A significant percent of CL cases belonged to Al-Kawasem subprovince (P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face (P=0.0001). We conclude that CL is a major health problem in Al-jabal Al-gharbi province of Libya. The presence of rodents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Being engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL suggest the presence of more than 1 species of Leishmania at Al-jabal Al-gharbi province. We propose that the 2 species responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species responsible for CL at Al-jabal Al-gharbi together with adoption of preventive and control programs are needed. PMID:23467624

  13. An epidemiological study of cutaneous leishmaniasis in Al-jabal Al-gharbi, Libya.

    PubMed

    Abdellatif, Manal Z M; El-Mabrouk, Khamis; Ewis, Ashraf A

    2013-02-01

    Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and its Al-jabal Al-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more affected than younger ones (P=0.0001). A significant percent of CL cases belonged to Al-Kawasem subprovince (P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face (P=0.0001). We conclude that CL is a major health problem in Al-jabal Al-gharbi province of Libya. The presence of rodents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Being engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL suggest the presence of more than 1 species of Leishmania at Al-jabal Al-gharbi province. We propose that the 2 species responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species responsible for CL at Al-jabal Al-gharbi together with adoption of preventive and control programs are needed.

  14. Aberrant distributions of nuclear pore complex proteins in ALS mice and ALS patients.

    PubMed

    Shang, Jingwei; Yamashita, Toru; Nakano, Yumiko; Morihara, Ryuta; Li, Xianghong; Feng, Tian; Liu, Xia; Huang, Yong; Fukui, Yusuke; Hishikawa, Nozomi; Ohta, Yasuyuki; Abe, Koji

    2017-03-24

    Nuclear pore complexes (NPCs) play important roles in traffic of molecules between the nucleus and cytoplasm, aberrant distributions of components of NPCs were demonstrated in C9orf72 amyotrophic lateral sclerosis (C9-ALS) patients, but it is elusive whether such abnormities are also the case with other cause of ALS disease. In the present study, we investigated the spatiotemporal distributions of RanGAP1 and 4 representative nucleoporins (GP210, NUP205, NUP107 and NUP50) of NPCs in human Cu/Zn superoxide dismutase-1 mutation transgenic (SOD1-Tg) mice and sporadic ALS patients. Compared with wild type (WT), these proteins displayed age-dependent and progressive nuclear precipitations, and cytoplasmic aberrant expressions in motor neurons of lumbar cord in SOD1-Tg mice from 10 to 18weeks (W). Double immunofluorescent analysis showed abnormal nuclear retention and apparent co-localizations of RanGAPl with NUP205 and NUP205 with NUPl07, meanwhile, GP210 with NUP205 mainly co-localized in the nuclear envelope (NE) of motor neurons. Furthermore, RanGAP1, GP210 and NUP50 showed similarly abnormal nuclear precipitations and cytoplasmic upregulations in SOD1-Tg mice and ALS patients, moreover, aberrant co-localizations of RanGAP1 with TDP-43 and NUP205 with TDP-43 were also observed in motor neurons. The present study indicated that the mislocalization of these proteins of NPCs may underlie the pathogenesis of ALS both in SOD1-Tg mice and human sporadic ALS patients, and these dysfunctions may be a fundamental pathway for ALS that is not specific only in C9-ALS but also in SOD1-ALS, which may be amenable to pharmacotherapeutic intervention.

  15. Non-volatile Al2O3 Memory using Nanoscale Al-rich Al2O3 Thin Film as a Charge Storage Layer

    NASA Astrophysics Data System (ADS)

    Nakata, Shunji; Saito, Kunio; Shimada, Masaru

    2006-04-01

    This article describes the fabrication process and capacitance-voltage (C-V) characteristics of a new non-volatile Al2O3 memory with nanoscale thin film deposited by electron-cyclotron-resonance sputtering. Al-rich Al2O3 shows characteristics somewhere between Al and Al2O3 in the refractive index and wet etching rate. C-V characteristics of Al-rich Al2O3 memory show a large hysteresis window due to the Al-rich structure, while there is no hysteresis window in the case of stoichiometric Al2O3. This memory is expected to stay non-volatile for several years or more because the capacitance value after writing and erasing operation remained almost unchanged after 4 h at T=85 °C. Also, another new memory structure comprising SiO2/Al2O3 and the Al-rich Al2O3 structure is proposed, which features increased mobility due to the reduction of electron scattering at the Si/Al2O3 interface.

  16. Metal clusters with hidden ground states: Melting and structural transitions in Al115(+), Al116(+), and Al117(+).

    PubMed

    Cao, Baopeng; Starace, Anne K; Judd, Oscar H; Bhattacharyya, Indrani; Jarrold, Martin F

    2009-09-28

    Heat capacities measured as a function of temperature for Al(115)(+), Al(116)(+), and Al(117)(+) show two well-resolved peaks, at around 450 and 600 K. After being annealed to 523 K (a temperature between the two peaks) or to 773 K (well above both peaks), the high temperature peak remains unchanged but the low temperature peak disappears. After considering the possible explanations, the low temperature peak is attributed to a structural transition and the high temperature peak to the melting of the higher enthalpy structure generated by the structural transition. The annealing results show that the liquid clusters freeze exclusively into the higher enthalpy structure and that the lower enthalpy structure is not accessible from the higher enthalpy one on the timescale of the experiments. We suggest that the low enthalpy structure observed before annealing results from epitaxy, where the smaller clusters act as a nucleus and follow a growth pattern that provides access to the low enthalpy structure. The solid-to-solid transition that leads to the low temperature peak in the heat capacity does not occur under equilibrium but requires a superheated solid.

  17. Mechanochemical synthesis and crystal structure of alpha'-AlD3 and alpha-AlD3.

    PubMed

    Brinks, Hendrik W; Istad-Lem, Andreas; Hauback, Bjørn C

    2006-12-28

    AlD3 AlD3 was synthesized by ball milling of 3LiAlD4 + AlCl3. Planetary ball milling at room temperature resulted in a mixture of AlD3 (alpha and alpha') and Al in addition to LiCl, whereas cryomilling at 77 K resulted in only AlD3 and LiCl. The AlD3 obtained was a mixture of about 2/3alpha and 1/3alpha'. Alpha' was determined by powder neutron diffraction to take the beta-AlF3 structure with space group Cmcm and a = 6.470(3), b = 11.117(5), and c = 6.562(2) A. It is built up of corner-sharing AlD6 octahedra in an open structure with hexagonal holes of radius 3.9 A. Alpha' slowly decomposes during storage at 40 degrees C. Alpha-AlD3 is also described by a corner-sharing AlD6 network but in a more dense ReO3-type arrangement. Both AlD3 modifications have slightly shorter Al-D distances compared to Na3AlD6, Na2LiAlD6, and K2NaAlH6.

  18. Ferromagnetic ordering in NpAl2: Magnetic susceptibility and 27Al nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Martel, L.; Griveau, J.-C.; Eloirdi, R.; Selfslag, C.; Colineau, E.; Caciuffo, R.

    2015-08-01

    We report on the magnetic properties of the neptunium based ferromagnetic compound NpAl2. We used magnetization measurements and 27Al NMR spectroscopy to access magnetic features related to the paramagnetic and ordered states (TC=56 K). While very precise DC SQUID magnetization measurements confirm ferromagnetic ordering, they show a relatively small hysteresis loop at 5 K reduced with a coercive field HCo~3000 Oe. The variable offset cumulative spectra (VOCS) acquired in the paramagnetic state show a high sensitivity of the 27Al nuclei spectral parameters (Knight shifts and line broadening) to the ferromagnetic ordering, even at room temperature.

  19. Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

    NASA Astrophysics Data System (ADS)

    Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

    2017-03-01

    The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating < the stainless steel with Al-Si coating < the stainless steel without any coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

  20. Superconductivity of Al/Al2O3 interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Palnichenko, A. V.; Shakhrai, D. V.; Avdonin, V. V.; Vyaselev, O. M.; Khasanov, S. S.

    2015-05-01

    A mixture of Al and α -Al2O3 has been subjected to a shock-wave pressure of ≃ 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 37 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.

  1. Superconductivity of Al/Al2O3 interface formed under shock-wave conditions

    NASA Astrophysics Data System (ADS)

    Shakhray, D. V.; Avdonin, V. V.; Palnichenko, A. V.; Vyaselev, O. M.

    2015-11-01

    A mixture of powdered Al and Al2O3 has been subjected to a shock-wave pressure of ≈ 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ≈ 37 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.

  2. Mechanical properties and electronic structures of Fe-Al intermetallic

    NASA Astrophysics Data System (ADS)

    Liu, YaHui; Chong, XiaoYu; Jiang, YeHua; Zhou, Rong; Feng, Jing

    2017-02-01

    Using the first-principles calculations, the elastic properties, anisotropy properties, electronic structures, Debye temperature and stability of Fe-Al (Fe3Al, FeAl, FeAl2, Fe2Al5 and FeAl3) binary compounds were calculated. The formation enthalpy and cohesive energy of these Fe-Al compounds are negative, and show they are thermodynamically stable structures. Fe2Al5 has the lowest formation enthalpy, which shows the Fe2Al5 is the most stable of Fe-Al binary compounds. These Fe-Al compounds display disparate anisotropy due to the calculated different shape of the 3D curved surface of the Young's modulus and anisotropic index. Fe3Al has the biggest bulk modulus with the value 233.2 GPa. FeAl has the biggest Yong's modulus and shear modulus with the value 296.2 GPa and 119.8 GPa, respectively. The partial density of states, total density of states and electron density distribution maps of the binary Fe-Al binary compounds are analyzed. The bonding characteristics of these Fe-Al binary compounds are mainly combination by covalent bond and metallic bonds. Meanwhile, also exist anti-bond effect. Moreover, the Debye temperatures and sound velocity of these Fe-Al compounds are explored.

  3. Oral Care for the Patient with ALS: A Guide for the Caregiver

    MedlinePlus

    ... with ALS and Caregivers Newly Diagnosed ALS Registry Military Veterans Caregivers Resources Order Materials Medicare Information ALS Insight Newsletter Living with ALS Resource Guides Families and ALS Resource Guide Medical Information Packet ALS ...

  4. Ab initio modeling of zincblende AlN layer in Al-AlN-TiN multilayers

    SciTech Connect

    Yadav, S. K.; Wang, J.; Liu, X. -Y.

    2016-06-13

    An unusual growth mechanism of metastable zincblende AlN thin film by diffusion of nitrogen atoms into Al lattice is established. Using first-principles density functional theory, we studied the possibility of thermodynamic stability of AlN as a zincblende phase due to epitaxial strains and interface effect, which fails to explain the formation of zincblende AlN. We then compared the formation energetics of rocksalt and zincblende AlN in fcc Al through direct diffusion of nitrogen atoms to Al octahedral and tetrahedral interstitials. Furthermore, the formation of a zincblende AlN thin film is determined to be a kinetically driven process, not a thermodynamically driven process.

  5. The β-decay of 22Al

    NASA Astrophysics Data System (ADS)

    Achouri, N. L.; de Oliveira Santos, F.; Lewitowicz, M.; Blank, B.; Äystö, J.; Canchel, G.; Czajkowski, S.; Dendooven, P.; Emsallem, A.; Giovinazzo, J.; Guillet, N.; Jokinen, A.; Laird, A. M.; Longour, C.; Peräjärvi, K.; Smirnova, N.; Stanoiu, M.; Thomas, J.-C.

    2006-03-01

    In an experiment performed at the LISE3 facility of GANIL, we studied the decay of 22Al produced by the fragmentation of a 36Ar primary beam. A β-decay half-life of T 1/2 = 91.1±0.5ms was measured. The β-delayed one- and two-proton emission as well as β-α and β-delayed γ-decays were measured and allowed us to establish a partial decay scheme for this nucleus. New levels were determined in the daughter nucleus 22Mg. The comparison with model calculations strongly favours a spin-parity of I π = 4+ for the ground state of 22Al.

  6. Development of SiAlON materials

    NASA Technical Reports Server (NTRS)

    Layden, G. K.

    1979-01-01

    Cold pressing and sintering techniques were used to produce ceramic test specimens in which the major phase was either Si3N4 or a solid solution having the beta Si3N4 structure. Additional components were incorporated to promote liquid phase sintering. Glass and/or crystalline phase were consequently retained in boundaries between Si3N4 grains which largely determined the physical properties of the bodies. Systems investigated most extensively included R-Si-Al-O-N (R = rare earth element) Zr-Si-Al-O-N, Y-Si-Be-O-N, and R1-R2-Si-O-N. Room temperature and 1370 C modulus of ruptured, 1370 C creep, and oxidation behavior are discussed in terms of phase relationships in a parent quinery, and relavent oxide systems.

  7. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Alexander, D.J.

    1995-05-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for (1)high-strength castable composition for turbochargers, furnace furniture, and hot-die applications; (2) castability (fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) hot fabricability of cast ingots. All of the issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes work completed to address some of these issues during the fourth quarter of FY 1994.

  8. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.; Santella, M.L.

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  9. Observable Proxies For 26 Al Enhancement

    SciTech Connect

    Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  10. Forging of FeAl intermetallic compounds

    SciTech Connect

    Flores, O.; Juarez, J.; Campillo, B.; Martinez, L.; Schneibel, J.H.

    1994-09-01

    Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

  11. Developing Wide-Spectrum Antiproteotoxicity Agents to Treat ALS

    DTIC Science & Technology

    2013-10-01

    phenotypes in C. elegans and mouse models of ALS. Progress Report Wang, Jiou 5 Overview: In this Aim, we hypothesize that increased HSF -1...2009a; Wang et al., 2009b). In a related finding, a reduction in HSF -1 activity dramatically precipitated neuronal toxicity in TDP-43 transgenic C...Fiesel et al., 2010; Sephton et al., 2010; Wu et al., 2010). Previously, we made an observation of genetic interaction between TDP-43 and HSF -1

  12. Adherent Al2O3 scales produced on undoped NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.

    1986-01-01

    Repeated oxidation and polishing of high purity Ni-15Cr-13Al has dramatically changed its cyclic oxidation behavior from nonadherent to adherent. No apparent change in scale phase, morphology or interface structure occurred during this transition, dismissing any mechanism based on pegging, vacancy sink, or growth stress. The principle change that did occur was a reduction in the sulfur content from 10 ppmw to 3 ppmw after 25 cycles at 1120 C. These observations are used to support the model of Al2O3 scale adherence put forth by Smeggil et al. which claims that Al2O3 scale spallation occurs due to sulfur segregation and bond deterioration at the oxide-metal interface.

  13. Fabrication of Fe-Al nanoparticles by selective oxidation of Fe-Al thin films

    NASA Astrophysics Data System (ADS)

    Jang, Pyungwoo; Shin, Seungchan; Jung, Chip-Sup; Kim, Kwang-Ho; Seomoon, Kyu

    2013-04-01

    The possibility of a new technique for fabricating nanoparticles from thin films using selective oxidation in an atmosphere mixture of water vapor and hydrogen was investigated. Fe-5wt.%Al films were RF-sputtered and annealed in the atmosphere mixture at 900°C for up to 200 min, in order to oxidize aluminum selectively. Thermodynamics simulation showed that temperatures exceeding 800°C are necessary to prevent iron from being oxidized, as confirmed by the depth profile of XPS. As the annealing time increased, the morphology of the 200-nm Fe-Al films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. The particulate 10- to 100-nm Fe-Al films showed super-paramagnetic behavior after the oxidation. Thus, a new technique for fabricating nanoparticles was successfully introduced using selective oxidation.

  14. Interdiffusion in the Mg-Al system and Intrinsic Diffusion in (Al3Mg2) Phase

    SciTech Connect

    Brennan, Sarah; Bermudez, Katrina; Kulkarni, Nagraj S; Sohn, Yong Ho

    2011-01-01

    Increasing use and development of lightweight Mg-alloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As a strengthening component, Al is one of the most important and common alloying elements for Mg-alloys. In this study, solid-to-solid diffusion couple techniques were employed to examine the interdiffusion between pure Mg and Al. Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopies (SEM) were employed to observe the formation of the intermetallics -Al12Mg17 and -Al3Mg2, but not -phase. Concentration profiles were determined using X-ray energy dispersive spectroscopy (XEDS). The growth constants and activation energies were determined for each intermetallic phase.

  15. 'Abd al-Rahman al-Sufi's 3-Step Magnitude System

    NASA Astrophysics Data System (ADS)

    Hafez, Ihsan; Stephenson, F. Richard; Orchiston, Wayne

    'Abd al-Rahmān al-ūfī's Book of the Fixed Stars dates from around AD 964 and is one of the most important medieval Arabic treatises on astronomy. In this paper we begin with a very brief introduction to the Book of the Fixed Stars. This book contains an extensive star catalogue that lists star coordinates and magnitude estimates for all of the Ptolemaic stars. However, in his book al-hūfī utilized three distinct intermediate magnitude values whereas Ptolemy only mentioned two. We believe that al-hūfī used what we have termed a '3-step intermediate magnitude system,' which is more accurate than Ptolemy's 2-step intermediate system. In this paper we examine in detail the accuracy of this unique 3-step system in comparison with Ptolemy's and modern magnitude values.

  16. Local stress-induced effects on AlGaAs/AlOx oxidation front shape

    SciTech Connect

    Chouchane, F.; Almuneau, G. Arnoult, A.; Lacoste, G.; Fontaine, C.; Cherkashin, N.

    2014-07-28

    The lateral oxidation of thick AlGaAs layers (>500 nm) is studied. An uncommon shape of the oxide tip is evidenced and attributed to the embedded stress distribution, inherent to the oxidation reaction. Experimental and numerical studies of the internal strain in oxidized Al{sub x}Ga{sub 1−x}As/GaAs structures were carried out by dark-field electron holography and finite element methods. A mapping of the strain distribution around the AlGaAs/oxide interface demonstrates the main role of internal stress on the shaping of the oxide front. These results demonstrate the high relevance of strain in oxide-confined III-V devices, in particular, with over-500-nm thick AlOx confinement layers.

  17. Rechargeable Al/Cl2 battery with molten AlCl4/-/ electrolyte.

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.; Burrows, B.

    1972-01-01

    A molten salt system based on Al- and Cl2 carbon electrodes, with an AlCl3 alkali chloride eutectic as electrolyte, offers promise as a rechargeable, high energy density battery which can operate at a relatively low temperature. Electrode kinetic studies showed that the electrode reactions at the Al anode were rapid and that the observed passivation phenomena were due to the formation at the electrode surface of a solid salt layer resulting from concentration changes on anodic or cathodic current flow. It was established that carbon electrodes were intrinsically active for chlorine reduction in AlCl3-alkali chloride melts. By means of a rotating vitreous carbon disk electrode, the kinetic parameters were determined.

  18. Response to de la Iglesia et al.

    PubMed

    Yetish, Gandhi; Kaplan, Hillard; Gurven, Michael; Wood, Brian; Pontzer, Herman; Manger, Paul R; Wilson, Charles; McGregor, Ronald; Siegel, Jerome M

    2016-04-04

    We wish to respond to the commentary of de la Iglesia et al. [1]. Studies comparing sleep in different communities have different goals. One frequent goal has been to determine how sleep is affected by manipulating specific 'modern' conditions. Many studies have investigated the effect of artificial light and electronic entertainment. Such studies have clearly shown that light, particularly blue light, delays sleep onset [2]. Studying the effect of artificial light on sleep was not a goal of our study.

  19. Hypermetabolism as a Risk Factor for ALS

    DTIC Science & Technology

    2012-07-01

    4 Introduction Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disorder characterized by the progressive loss of motor...Gonzalez de Aguilar JL, & Loeffler JP: Evidence for defective energy homeostasis in amyotrophic lateral sclerosis : benefit of a high-energy diet in a...and supplements in amyotrophic lateral sclerosis and other neurodegenerative disorders. Curr Opin Clin Nutr Metab Care 6:631- 43, 2002. 8. Lagier

  20. Psychosocial adjustment to ALS: a longitudinal study.

    PubMed

    Matuz, Tamara; Birbaumer, Niels; Hautzinger, Martin; Kübler, Andrea

    2015-01-01

    For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to ALS. We aimed to investigate the evolution of psychosocial adjustment to ALS and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55% of the variance of severity of depressive symptoms and 47% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to ALS. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with ALS.

  1. Psychosocial adjustment to ALS: a longitudinal study

    PubMed Central

    Matuz, Tamara; Birbaumer, Niels; Hautzinger, Martin; Kübler, Andrea

    2015-01-01

    For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to ALS. We aimed to investigate the evolution of psychosocial adjustment to ALS and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55% of the variance of severity of depressive symptoms and 47% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to ALS. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with ALS. PMID:26441696

  2. An Al Qaeda Way of War

    DTIC Science & Technology

    2012-05-17

    which may lead to the refinement of strategy and policy. Therefore, political authorities must be closely integrated with military planners to ensure...series of decisive points that lead to control of geographic or force- oriented objectives. Operations designed using lines of operations generally...Ramzi Yousef, the individual responsible for leading the attack, was trained in Afghanistan during the war with the Soviet Union.68 Al Qaeda utilized

  3. Structure and ductility of TiAl

    SciTech Connect

    Imayev, R.; Salishchev, G.; Imayev, V.; Shagiev, M.; Kuznetzov, A.

    1995-12-31

    The effect of structural factors (grain size and grain boundary structure) and strain rate on the deformation mechanism and ductility of TiAl in the temperature range of brittle-to-ductile transition and at room temperature was systematically investigated. It has been established that it is possible to substantially affect the deformation mechanism and ductility of this intermetallic by controlling structural factors, particularly the grain size, and varying the strain rate.

  4. Al Kazim Water Supply, Nassriya, Iraq

    DTIC Science & Technology

    2008-07-23

    water network a perimeter fence Project Assessment Objectives. The objective of this project assessment was to provide real-time information...network connecting to the existing water network . To date, the Al Kazim Water Supply project results are consistent with the original contract...treatment plant, an above ground storage reservoir, a pipe network connecting to the existing water network , and an approximately 160 linear meter

  5. Al Ager Water Compact Unit, Nassriya, Iraq

    DTIC Science & Technology

    2008-07-22

    plant was to contain a reverse osmosis unit, an above-ground storage reservoir, a pipe network connecting to the existing water network , and a...the existing water network , and a perimeter fence for the new facility. To date, the Al Ager Water Compact Unit project results are consistent with...of 110 millimeter (mm) polyvinyl chloride (PVC), connection to the existing water network , and a perimeter fence measuring approximately 50-m x 30-m

  6. Hypermetabolism as a Risk Factor for ALS

    DTIC Science & Technology

    2013-09-01

    Ubiquitinated TDP-43 in frontotemporal lobar degeneration and amyotrophic lateral sclerosis . Science 314, 130–133 (2006). 2. Weihl, C. C. et al. TDP-43...body fat, likely working through a protein called Tbc1d1 which is known to control fat metabolism in skeletal muscle . To test this hypothesis, we...generated conditional Tdp-43 knockout mice using a muscle -specific (MLC) driver of Cre recombinase. Loss of Tdp-43 in skeletal muscle led to adult onset

  7. 75 FR 5120 - United States, et al. v. Stericycle, Inc., et al.; Proposed Final Judgment and Competitive Impact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-01

    ... Antitrust Division United States, et al. v. Stericycle, Inc., et al.; Proposed Final Judgment and... with the United States District Court for the District of Columbia in United States, et al. v. Stericycle, Inc., et al., Civil Action No. 1:09-cv- 02268. On November 30, 2009, the United States and...

  8. Investigation of Phase Equilibria and Some Properties of Alloys of Ti-Al-Fe and Ti-Al-V Systems,

    DTIC Science & Technology

    Some data on the structure and properties of Ti-Al-Fe alloys are presented. The phase equilibria in alloys in the system Ti-Al-V were studies...However, the data available in the literature on phase equilibria in the systems Ti-Al-Fe and Ti-Al-V require refinement, as they are insufficiently

  9. An ALS (Advanced Light Source) handbook

    SciTech Connect

    Not Available

    1988-11-01

    This booklet aims to provide the prospective user of the Advanced Light Source with a concise description of the radiation a researcher might expect at his or her experimental station. The focus is therefore on the characteristics of the light that emerges from insertion devices and bending magnets and on how components of the beam lines further alter the properties of the radiation. The specifications and operating parameters of the ALS injection system and storage ring are of only peripheral interest. To this end, Sections 3 and 5 and most of Section 4 are devoted to summary presentations, by means of performance plots and tabular compilations, of radiation characteristics at the ALS--spectral brightness, flux, coherent power, resolution, time structure, etc.--assuming a representative set of four undulators and one wiggler and a corresponding set of five beam lines. As a complement to these performance summaries, Section 1 is a general introductory discussion of synchrotron radiation and the ALS, and Section 2 provides a compendious introduction to the characteristics of synchrotron radiation from bending magnets, wigglers, and undulators. In addition, Section 4 briefly introduces the theory of diffraction grating and crystal monochromators. 15 refs., 28 figs., 5 tabs.

  10. Diet and dietetics in al-Andalus.

    PubMed

    Salas-Salvadó, Jordi; Huetos-Solano, Maria D; García-Lorda, Pilar; Bulló, Mònica

    2006-08-01

    Al-Andalus society (711-1492) based its idea of health on the wisdom of Classical Greece, the Hippocratic-Galenic theories, as well as the Persian and Hindu cultures. The twelfth century in al-Andalus is considered to be the most prolific period for works of a scientific and technical nature. At the time, the main treatises on dietetics were written and this science reached its widest expression with such leading figures as Ibn Wāfīd, Avenzoar, Averroes and Maimonides, whose works revealed the first scientific knowledge on the nutritional processes of the human body. Diet was regarded as being essential for health and the prevention of disease. Dietary guidelines were written for different age groups, different body types and different seasons of the year. The amount of food to be ingested, the number of meals recommended and the order in which the food should be consumed were all issues that were discussed. A variety of foods were thought to have medicinal properties, some of which are known today. The diet in al-Andalus was varied and very probably made a substantial contribution to the origin of the present-day Mediterranean diet, rich in olive oil, wholemeal cereals, fruit and vegetables, fish, lamb, poultry, nuts and spices. We also find that many of the terms in current use in diet and agriculture are a living testimony to the Arabic influence, as are many of the dishes of our varied Mediterranean gastronomy.

  11. Fabrication of NiAl Microreactors

    SciTech Connect

    Alman, D.E.; Wilson, R.D.; Dewey, T.; Paul, B.K.

    2000-07-01

    Chemical microreactors offer opportunities for portable powder generation, on-site waste remediation, point-of-use chemical synthesis, and heat-transfer. The material requirements for this application include chemical inertness and the ability to be fabricated into structures that contain internal features of complex geometries and small (<250 μm) dimensions. It has been recognized that materials with limited formability, like ceramics and intermetallics, will be required for high temperature applications. Reactors from these materials have been produced from powder tapes. However, problems associated with binder removal and sintering result in dimensional instability of the internal geometry which degrades the performance of the reactor. In this paper, a method for forming an array of internal microchannels in a NiAl device that avoids the dimensional instability of powder processing is demonstrated. Microchannels are precision machined (via laser ablation) into elemental Ni and Al foils. During bonding, the foils are converted into NiAl. Results show that this is a viable method for producing aluminide-based structures containing complex, internal features.

  12. Microplastic flow in SIC/AL composites

    SciTech Connect

    Shi, N.; Arsenault, R.J.

    1995-12-31

    Experimentally it has been determined that if a composite containing a reinforcement which has a different (in general lower) thermal coefficient of expansion as compared to the matrix, then upon cooling from the processing or annealing temperature, plastic relaxation of the misfit strain will occur. Also, experimentally it has been shown that as the size of the reinforcement is increased, i.e., from small spheres to large spheres, there is a decrease in the summation of the effective plastic strain in the matrix. In other words there is a decrease in the average dislocation density in the matrix. However, if the shape of the reinforcement is changed from spherical to short fiber to continuous filament, then the dislocation density increases. This experimental data is obtained at a constant volume fraction. A very simple model of plastic relaxation based on prismatic punching of dislocations from the interface can account for the decrease in the dislocation density with an increase reinforcement size, and the increase in dislocation density when changing the shape from a sphere to a continuous filament. A FEM analysis of the shape factor is also capable of predicting the correct trend. However, at present the continuum mechanics methods that have been investigated can not predict the size dependence. A simple model to explain the size effect in Al{sub 2}O{sub 3}/NiAl composites based on the deformation characteristics of NiAl will be discussed.

  13. A comparative wear study on Al-Li and Al-Li/SiC composite

    SciTech Connect

    Okumus, S. Cem Karslioglu, Ramazan Akbulut, Hatem

    2013-12-16

    Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al{sub 2}O{sub 3} ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms{sup −1} and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.

  14. Evaluation of aerial microbial pollutants in Al-Haram Al-Nabawi during pilgrimage of 2013.

    PubMed

    Alananbeh, Kholoud M; Boquellah, Nahla; Kaff, Nadia Al; Ahmadi, Majid Al

    2017-01-01

    Al-Madinah Al-Munawwarah is the second holiest site in Islam. The possibility of new emerging microbes is valid due to the increased number of pilgrims. The objectives of the current study were to estimate the numbers of fungi and bacteria inside and outside Al-Haram Al-Nabawi and to find whether new bacterial and fungal species have emerged compared to previous studies. Air samples were collected twice a day from 12 spots and four directions during the pilgrim year of 2013 for four consecutive weeks by using the sedimentation method. Thirty five genera and fifty eight species were identified. The most recovered bacterial genera were Staphylococcus, Micrococcus, Bacillus, and Dermacoccus with 32.47%, 18.18%, 12.85%, and 11.23%, respectively. Fifty nine isolates of fungi were molecularly identified. Aspergillus species had the highest percentage (78%). The other fungal genera identified (Alternaria triticina, Emericella nidulans, Emericella striata, Mucor circinelloides, Penicillium chrysogenum, Penicillium minioluteum, Rhizopus arrhizus, Rhizopus oryzae, and Syncephalastrum racemosum) had less than 5% frequency. In places such as Al-Haram Al-Nabawi, a large and crowded public (millions) exist especially during pilgrimages and Ramadan, thus, exposure to microorganisms is high. On the other hand, microorganism infectivity depends on many factors including their virulence, landing site, and person's immunity. For those reasons, many aspects should be considered to avoid aerosol contaminants.

  15. Internal photoemission in Ag-Al2O3-Al junctions

    NASA Technical Reports Server (NTRS)

    Guedes, J. M. P.; Slayman, C. W.; Gustafson, T. K.; Jain, R. K.

    1979-01-01

    The magnitude of the photon-induced current in Ag-Al2O3-Al metal-oxide-metal junctions has been studied as a function of photon energy and angle of incident radiation. Photocurrents were theoretically analyzed on the basis of a modified vacuum photoemission model (Jain, 1975; Slayman et al., to be published). Optical constants previously reported in the literature (Irani et al., 1971; Ehnrereich et al., 1963) were used to calculate the true spatial generation rate in Ag and Al as a function of the angle, polarization of incident radiation, and film thickness. Results were found to be in very good agreement with experimentally determined values for a tunable dye laser with a KDP doubling crystal pumped by a Q-switched Nd:YAG laser with a LiIO3 doubling crystal. The system provided risetimes of 50 ns or less and peak powers of 10 W. Under short circuit conditions, the photoresponse to incident power was linear up to available power densities of 10 kW/sq cm. Quantum efficiencies of about 0.1% at zero-bias, near 3.8 eV under P polarization, were typically observed.

  16. Redistribution of Ti and Al in deuterium charged TiAl

    NASA Technical Reports Server (NTRS)

    Legzdina, D.; Robertson, I. M.; Birnbaum, H. K.

    1992-01-01

    The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration.

  17. Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles

    PubMed Central

    Abedini, Alam; Saion, Elias; Larki, Farhad; Zakaria, Azmi; Noroozi, Monir; Soltani, Nayereh

    2012-01-01

    Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. PMID:23109893

  18. Unveiling the Semicoherent Interface with Definite Orientation Relationships between Reinforcements and Matrix in Novel Al3BC/Al Composites.

    PubMed

    Zhao, Yongfeng; Qian, Zhao; Ma, Xia; Chen, Houwen; Gao, Tong; Wu, Yuying; Liu, Xiangfa

    2016-10-05

    High-strength lightweight Al-based composites are promising materials for a wide range of applications. To provide high performance, a strong bonding interface for effective load transfer from the matrix to the reinforcement is essential. In this work, the novel Al3BC reinforced Al composites have been in situ fabricated through a liquid-solid reaction method and the bonding interface between Al3BC and Al matrix has been unveiled. The HRTEM characterizations on the Al3BC/Al interface verify it to be a semicoherent bonding structure with definite orientation relationships: (0001)Al3BC//(11̅1)Al;[112̅0]Al3BC//[011]Al. Periodic arrays of geometrical misfit dislocations are also observed along the interface at each (0001)Al3BC plane or every five (11̅1)Al planes. This kind of interface between the reinforcement and the matrix is strong enough for effective load transfer, which would lead to the evidently improved strength and stiffness of the introduced new Al3BC/Al composites.

  19. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Smialek, James L.; Barrett, Charles A.

    1988-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al2O3 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  20. Unexpected Stability of Al4H6: a Borane Analog?

    NASA Astrophysics Data System (ADS)

    Xi, Li; Grubisic, Andrej; Stokes, Sarah; Gantefor, Gerd; Bowen, Kit; Boggavarapu, Kiran; Willis, Mary; Jena, Puru; Burgert, Ralph; Schnockel, Hans; Cordes, James

    2007-03-01

    While boron has many hydrides, aluminum has been thought to exhibit relatively few. A combined anion photoelectron and density functional theory computational study of the Al4H6^- anion, and its corresponding neutral, Al4H6, showed that Al4H6 can be understood in terms of the Wade-Mingos rules for electron counting, suggesting that it may be a borane analog. The data support an Al4H6 structure with a distorted tetrahedral aluminum atom framework, four terminal Al-H bonds, and two sets of counter-positioned Al-H-Al bridging bonds. The large HOMO-LUMO gap found for Al4H6 together with its exceptionally high heat of combustion further suggests that Al4H6 may be an important energetic material, if it can be prepared in bulk. This report announces the opening of a new chapter in aluminum-hydrogen chemistry.

  1. Creep and Toughness of Cryomilled NiAl Containing Cr

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Aikin, Beverly; Salem, Jon

    2000-01-01

    NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approx. 10 vol % Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN+10.5Cr, however, possessed a toughness twice that determine for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

  2. The Nature of Interfaces in Al-1050/Al-1050 and Al-1050/Mg-AZ31 Couples Joined by Magnetic Pulse Welding (MPW)

    NASA Astrophysics Data System (ADS)

    Stern, A.; Aizenshtein, M.; Moshe, G.; Cohen, S. R.; Frage, N.

    2013-07-01

    The microstructure and the phase composition of the interfaces of Al-1050/Al-1050 and Al-1050/Mg-AZ31 magnetic pulse welding (MPW) joints were characterized by SEM and TEM analyses. The mechanical properties were tested by nanoindentation. Properties of the Al-1050/Al-1050 interface joint were established. The interface is almost free from Al3Fe precipitates, which are present in the base metal. The hardness value is higher than that of the base metal; however, values of the Young's modulus of the interface and base metal are similar. It was suggested that the interface evolution in the Al-1050/Al-1050 system includes local melting and rapid solidification of the base materials. A wavy shaped heterogeneous interface was detected in the Al-1050/Mg-AZ31 joints. Some areas are free from visible intermetallic phases (IMPs), while others contain pockets of relatively coarse intermetallic precipitates. The presence of a relatively large fraction of globular porosity at the interface indicates that local melting takes place in the course of MPW. TEM characterization of regions free of IMPs at the interface reveals regions consisting of fcc supersaturated Al-Mg solid solution, apparently formed as a result of local mechanical alloying during MPW. In other regions, the composition and structure correspond to the Mg17Al12 phase, which was probably formed by local melting and rapid solidification.

  3. Effect of nitrogen incorporation into Al-based gate insulators in AlON/AlGaN/GaN metal-oxide-semiconductor structures

    NASA Astrophysics Data System (ADS)

    Asahara, Ryohei; Nozaki, Mikito; Yamada, Takahiro; Ito, Joyo; Nakazawa, Satoshi; Ishida, Masahiro; Ueda, Tetsuzo; Yoshigoe, Akitaka; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2016-10-01

    The superior physical and electrical properties of aluminum oxynitride (AlON) gate dielectrics on AlGaN/GaN substrates in terms of thermal stability, reliability, and interface quality were demonstrated by direct AlON deposition and subsequent annealing. Nitrogen incorporation into alumina was proven to be beneficial both for suppressing intermixing at the insulator/AlGaN interface and reducing the number of electrical defects in Al2O3 films. Consequently, we achieved high-quality AlON/AlGaN/GaN metal-oxide-semiconductor capacitors with improved stability against charge injection and a reduced interface state density as low as 1.2 × 1011 cm-2 eV-1. The impact of nitrogen incorporation into the insulator will be discussed on the basis of experimental findings.

  4. Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships

    SciTech Connect

    Kim, Hyong June

    2011-01-01

    Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

  5. Covalent bonds in AlMnSi icosahedral quasicrystalline approximant

    PubMed

    Kirihara; Nakata; Takata; Kubota; Nishibori; Kimura; Sakata

    2000-10-16

    Electron density distributions were obtained using the maximum entropy method with synchrotron radiation powder data. In the metallic Al12Re, metallic bonding was observed for the icosahedral Al12 cluster with central Re atom. In the nonmetallic alpha-AlMnSi 1/1 approximant, covalent bonds were found in the electron density distribution of the Mackay icosahedral cluster without central atom. Rather than the Hume-Rothery mechanism, the covalency of Al (Si) icosahedron and that between Al (Si) and Mn atoms is considered to be the origin of the pseudogap and nonmetallic behavior of alpha-AlMnSi.

  6. Development of SiAlON materials

    NASA Technical Reports Server (NTRS)

    Layden, G. K.

    1977-01-01

    Cold pressing and sintering techniques were used to produce ceramic bodies in which the major phase was beta prime Si3-Al-O-N4 solid solution. A variety of foreign oxides were used to promote liquid phase sintering, and this resulted in the incorporation of additional solid phases in the ceramic bodies which controlled elevated temperature properties. None of the bodies studied to date exhibited both adequate high temperature mechanical properties and oxidation resistance. Criteria are suggested to guide the formulation of bodies with improved high temperature properties.

  7. Ultranarrow AuPd and Al wires

    SciTech Connect

    Altomare, Fabio; Chang, Albert M.; Melloch, Michael R.; Hong Yuguang; Tu, Charles W.

    2005-04-25

    In this letter, we discuss a versatile template technique aimed to the fabrication of sub-10 nm wide wires. Using this technique, we have measured AuPd wires, 12 nm wide and as long as 20 {mu}m. Even materials that form a strong superficial oxide, and thus not suited to be used in combination with other techniques, can be employed. In particular, we have measured Al wires, with lateral width smaller or comparable to 10 nm, and length exceeding 10 {mu}m.

  8. Tumor-Wachstumsmodellierung als parametrisches Bildregistrierproblem

    NASA Astrophysics Data System (ADS)

    Becker, Stefan; Jungmann, Jan Ole; Mang, Andreas; Buzug, Thorsten M.

    In der vorliegenden Arbeit stellen wir ein neues Modell zur Kopplung des Tumormasseeffektes an die, der Wachstumsmodellierung unterliegende, anisotrope Reaktionsdiffusionsgleichung vor. Die Gleichung wird auf einem hochaufgelösten Voxelgitter diskretisiert. Eine Modellierung der Anisotropie des Diffusionsprozesses ermöglicht die Integration von Diffusions-Tensor-Bildgebungsdaten. Die raumfordernde Wirkung des Tumors wird als parametrisches Bildregistrierproblem aufgefasst. Hierbei wird die resultierende Verteilung der Tumorzellkonzentration in die zu optimierende Zielfunktion integriert. Erste qualitative Ergebnisse zeigen, dass eine Minimierung der aufgestellten Zielfunktion zu einer plausiblen Modellierung des Masseeffektes führt.

  9. Operating experience with the ALS linac

    SciTech Connect

    Selph, F.; Massoletti, D.

    1991-05-01

    The linac injector for the Advanced Light Source (ALS) at LBL was recently put into operation. Energy is 50 MeV, frequency 3 GHz. The electron gun delivers up to 6nC in a 3.0-ns bunch at 120 kV. A train of bunches is injected into a 1-Hz booster and accelerated to 1.5 GHz for storage ring injection. A magnetic analysis system is used for optimizing the linac. Measured beam properties from the gun and after acceleration in the linac are described. 9 refs., 3 figs.

  10. On the mesoscopic origins of high viscosities in some polyelectrolyte-surfactant mixtures

    SciTech Connect

    Hoffmann, Ingo; Farago, Bela; Schweins, Ralf; Falus, Peter; Sharp, Melissa; Prévost, Sylvain; Gradzielski, Michael

    2015-08-21

    Oppositely charged polyelectrolyte (PE) surfactant mixtures allow the control of rheological parameters of a solution even at fairly low concentrations. For example, addition of 0.3 wt. % of anionic surfactant to a 1 wt. % solution of the polycation JR 400 increases the viscosity by 4 orders of magnitude. Recently, we could show that this increase is related to the formation of mixed, rod-like PE/surfactant aggregates which interconnect several polyelectrolyte chains [Hoffmann et al., Europhys. Lett. 104, 28001 (2013)]. In this paper, we refine our structural model of the aggregates to obtain a more consistent picture of their internal structure for different anionic surfactants. Combining small angle neutron scattering (SANS) and neutron spin-echo (NSE) allows us to determine the size of the aggregates. By comparing different contrasts, the internal structure of the aggregates can be elucidated and it is seen that the PE in the aggregates retains a relatively high freedom of movement. We proceeded to investigate the influence of the surfactant concentration and the surfactant type on structure and dynamics of the mixed aggregates. It is seen that the structural parameters of the aggregates depend very little on the surfactant concentration and headgroup. However, it is crucial to incorporate a sufficient amount of PE in the aggregates to increase the viscosity of the aggregates. By comparing viscous samples at 1 wt. % PE concentration with samples at a PE concentration of 0.3 wt. %, where no significant increase in viscosity is observed, we find that similar aggregates are formed already at this lower PE concentrations. However, the amount of PE incorporated in them is insufficient to interconnect several PE chains and therefore, they do not increase viscosity. So, our detailed investigation combining contrast variation SANS and NSE does not only allow to explain the viscosity behavior but also to deduced detailed information regarding the structures and

  11. ALS Along the Axons - Expression of Coding and Noncoding RNA Differs in Axons of ALS models.

    PubMed

    Rotem, Nimrod; Magen, Iddo; Ionescu, Ariel; Gershoni-Emek, Noga; Altman, Topaz; Costa, Christopher J; Gradus, Tal; Pasmanik-Chor, Metsada; Willis, Dianna E; Ben-Dov, Iddo Z; Hornstein, Eran; Perlson, Eran

    2017-03-16

    Amyotrophic lateral sclerosis (ALS) is a multifactorial lethal motor neuron disease with no known treatment. Although the basic mechanism of its degenerative pathogenesis remains poorly understood, a subcellular spatial alteration in RNA metabolism is thought to play a key role. The nature of these RNAs remains elusive, and a comprehensive characterization of the axonal RNAs involved in maintaining neuronal health has yet to be described. Here, using cultured spinal cord (SC) neurons grown using a compartmented platform followed by next-generation sequencing (NGS) technology, we find that RNA expression differs between the somatic and axonal compartments of the neuron, for both mRNA and microRNA (miRNA). Further, the introduction of SOD1(G93A) and TDP43(A315T), established ALS-related mutations, changed the subcellular expression and localization of RNAs within the neurons, showing a spatial specificity to either the soma or the axon. Altogether, we provide here the first combined inclusive profile of mRNA and miRNA expression in two ALS models at the subcellular level. These data provide an important resource for studies on the roles of local protein synthesis and axon degeneration in ALS and can serve as a possible target pool for ALS treatment.

  12. Revisiting the Al/Al2O3 Interface: Coherent Interfaces and Misfit Accommodation

    DOE PAGES

    Pilania, Ghanshyam; Thijsse, Barend J.; Hoagland, Richard G.; ...

    2014-03-27

    We report the coherent and semi-coherent Al/α-Al2O3 interfaces using molecular dynamics simulations with a mixed, metallic-ionic atomistic model. For the coherent interfaces, both Al-terminated and O-terminated nonstoichiometric interfaces have been studied and their relative stability has been established. To understand the misfit accommodation at the semi-coherent interface, a 1-dimensional (1D) misfit dislocation model and a 2-dimensional (2D) dislocation network model have been studied. For the latter case, our analysis reveals an interface dislocation structure with a network of three sets of parallel dislocations, each with pure-edge character, giving rise to a pattern of coherent and stacking-fault-like regions at the interface.more » Structural relaxation at elevated temperatures leads to a further change of the dislocation pattern, which can be understood in terms of a competition between the stacking fault energy and the dislocation interaction energy at the interface. In conclusion, our results are expected to serve as an input for the subsequent dislocation dynamics models to understand and predict the macroscopic mechanical behavior of Al/α-Al2O3 composite heterostructures.« less

  13. Revisiting the Al/Al2O3 Interface: Coherent Interfaces and Misfit Accommodation

    PubMed Central

    Pilania, Ghanshyam; Thijsse, Barend J.; Hoagland, Richard G.; Lazić, Ivan; Valone, Steven M.; Liu, Xiang-Yang

    2014-01-01

    We study the coherent and semi-coherent Al/α-Al2O3 interfaces using molecular dynamics simulations with a mixed, metallic-ionic atomistic model. For the coherent interfaces, both Al-terminated and O-terminated nonstoichiometric interfaces have been studied and their relative stability has been established. To understand the misfit accommodation at the semi-coherent interface, a 1-dimensional (1D) misfit dislocation model and a 2-dimensional (2D) dislocation network model have been studied. For the latter case, our analysis reveals an interface dislocation structure with a network of three sets of parallel dislocations, each with pure-edge character, giving rise to a pattern of coherent and stacking-fault-like regions at the interface. Structural relaxation at elevated temperatures leads to a further change of the dislocation pattern, which can be understood in terms of a competition between the stacking fault energy and the dislocation interaction energy at the interface. Our results are expected to serve as an input for the subsequent dislocation dynamics models to understand and predict the macroscopic mechanical behavior of Al/α-Al2O3 composite heterostructures. PMID:24670940

  14. Millimeter distance effects of surface plasmon polaritons in electroformed Al-Al2O3-Ag diodes

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2017-02-01

    Electroforming of metal-insulator-metal diodes is a soft dielectric breakdown that changes the high resistance of as-prepared diodes to a low resistance state. Electroforming of Al-Al2O3-metal diodes with anodic Al2O3 results in voltage-controlled negative resistance in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM). EL is due to electrons injected at the Al-Al2O3 interface combining with radiative defects in Al2O3. Surface plasmon polaritons (SPPs) are electromagnetic waves that can be excited by photons or electrons. SPPs are confined to a metal-dielectric interface, cause large electric fields in the metal and dielectric, and have ranges of micrometers. The temperature dependence of I-V curves, EL, and EM of a group of electroformed Al-Al2O3-Ag diodes with Al2O3 thicknesses between 12 nm and 20 nm, group A, was measured between 200 K and 300 K. After a sequence of temperature measurements, the Al-Al2O3-Ag diodes, the Al-Al2O3 regions between diodes, and portions of the Ag on the glass region that provides contacts to the diodes are darkened. The range of darkening is >7 mm in a diode with 12 nm of Al2O3 and 2.0-3.5 mm in diodes with Al2O3 thicknesses between 14 nm and 20 nm. Darkening is attributed to the occurrence of SPPs generated by EL photons at the Ag-Al2O3 and Al-Al2O3 interfaces. The results are compared to a second group of Al-Al2O3-Ag diodes with identical Al2O3 thicknesses, group B, that were prepared in the same way as the diodes of group A except for a difference in the deposition of Al films for the two groups. Al-Al2O3-Ag diodes of group B exhibit enhanced EL, which is attributed to spontaneous emission of recombination centers in Al2O3 being enhanced by large electromagnetic fields that are due to SPPs that are generated by EL photons.

  15. TEM characterization of Al/Al{sub 2}O{sub 3} composite fabricated by reactive metal infiltration

    SciTech Connect

    Gao, Y.; Jia, J.; Loehman, R.E.; Ewsuk, K.G.

    1994-12-31

    The microstructure of Al/{alpha}-Al{sub 2}0{sub 3} composites made by infiltrating Al into dense mullite preforms has been characterized using transmission electron microscopy. Observations revealed that the formation of the Al/Al{sub 2}0{sub 3} composites involves three stages. Initially, Al infiltrates into a dense mullite preform through grain boundary diffusion, and reacts with mullite at grain boundaries to form a partial reaction zone. Then, a complete reaction takes place in the reaction region between the partial reaction zone and the full reaction zone to convert the dense mullite preform to a composite of {alpha}-Al{sub 2}0{sub 3} (matrix) and an Al-Si phase (thin channels). Finally, the reduced Si from the reaction diffuses out of the Al/Al{sub 2}0{sub 3} composite through the metal channels, whereas Al from the molten Al pool is continuously drawn to the reaction region until the mullite preform is consumed or the sample is removed from the molten Al pool. Based on the observed microstructure, infiltration mechanisms have been discussed, and a growth model of the composites is proposed in which the process involves repeated nucleation of Al{sub 2}0{sub 3} grains and grain growth.

  16. Oxidation of TiAl3 and L12 Coatings on Ti-45Al-5Nb Alloy at 1173K

    NASA Astrophysics Data System (ADS)

    Nishimoto, Takumi; Kitajima, Yuri; Hayashi, Shigenari; Narita, Toshio

    Oxidation behavior of TiAl3 and L12 coated Ti-45at%Al-5at%Nb alloys at 1173K in air was investigated using mass gain measurement, field emission scanning electron microscopy, transmission electron microscopy, electron-probe microanalysis, glow discharge optical electron spectroscopy, and glancing angle X-ray diffraction analysis. The TiAl3 formed meta-stable alumina θ-Al2O3, while the oxide scale on the L12 consisted of a duplex structure with an outer rutile TiO2 and an inner α-Al2O3. During the very initial stages of oxidation both Ti and Al in the L12 coating could be oxidized, and then the faster diffusing Ti goes out to form an outer, continuous Ti-rich oxide which covers the slow growing Al2O3. In case of the TiAl3 an outer, continuous TiO2 layer was not observed because of the smaller amount of Ti in the TiAl3. It could be concluded that the outer, Ti-rich oxide enhanced a phase transformation of Al2O3 from θ to α. To elucidate the Ti effect, Ti-vapor treated TiAl3 and Ni-50at%Al were oxidized at 1173K in air, and showed formation of an α-Al2O3, in contrast to θ-Al2O3 on their bare alloys.

  17. Fabrication of Al/Al3Ti Functionally Graded Materials by Reaction Centrifugal Mixed-Powder Method

    NASA Astrophysics Data System (ADS)

    El-Hadad, Shimaa; Sato, Hisashi; Miura-Fujiwara, Eri; Watanabe, Yoshimi

    2011-01-01

    Formation of compositional gradient in Al/Al3Ti Functionally graded materials (FGMs) fabricated by the centrifugal method (CM) depends mainly on the centrifugal force and the processing temperature. In this study, a novel centrifugal method, reaction centrifugal mixed-powder method (RCMPM), was proposed to fabricate Al/Al3Ti FGMs under fixed centrifugal force (G=80). The effects of RCMPM processing temperature on the formation of Al3Ti intermetallics, its morphology and its distribution in the fabricated Al/Al3Ti FGMs have been investigated. Fine granular Al3Ti were observed at relatively lower processing temperature while the known coarse platelet-like particles of Al3Ti could be achieved at higher casting temperatures. Moreover, Ti3Al intermetallics compound and unreacted Ti phases are also observed along with Al3Ti particles. In addition, distribution of Al3Ti intermetallics size and their volume fraction showed a significant change when the Al/Al3Ti FGMs processed at different temperatures relative to the liquidus temperature of the master alloy.

  18. Transplacental passage of 26Al from pregnant rats to fetuses and 26Al transfer through maternal milk to suckling rats

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Matsuzaki, H.; Kobayashi, T.; Tada, W.; Ohki, Y.; Kakimi, S.; Kobayashi, K.

    2000-10-01

    Aluminium (Al) is toxic to the growth of fetuses and sucklings. However, the incorporation of Al into fetuses and sucklings in the periods of gestation and lactation has not been well clarified because Al lacks a suitable isotope for a tracer experiment. In this study, we used 26Al (a radioisotope of Al with half-life of 716,000 yr) as a tracer, and measured 26Al incorporation into fetuses and sucklings by accelerator mass spectrometry (AMS). To investigate Al incorporation into fetuses through transplacental passage, 26Al ( 26AlCl 3) was subcutaneously injected into pregnant rats on day 15 of gestation. 26Al was also subcutaneoulsy injected into lactating rats from day 1 to day 20 postpartum. By day 20 of gestation, 0.2% of the 26Al injected into a pregnant rat had been transferred to the fetuses, and 26Al was detected in the brain and liver of the fetuses. On day 9 postpartum, high levels of 26Al were demonstrated in the brain, liver, kidneys and blood of suckling rats. It is concluded that 26Al subcutaneously injected into pregnant rats and/or lactating rats is incorporated into their offspring through transplacental passage and/or maternal milk.

  19. Hot Corrosion Performance of AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa Coatings Deposited by Atmospheric Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Tao, Chong; Wang, Lei; Cheng, Nailiang; Hu, Hengfa; Liu, Yang; Song, Xiu

    2016-04-01

    AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa coatings were deposited on 316L stainless steel substrate using atmospheric plasma spraying, respectively, in order to improve the oxidation and corrosion resistance. The hot corrosion performance of the coatings at 700 and 900 °C were studied, and the detailed microstructures and phase composition of the coatings were analyzed using x-ray diffraction, scanning electron microscope with energy dispersive spectrometer, and transmission electron microscope. The results show that both coatings are structurally featured by slatted layers, consisting of amorphous phase, Cr2O3, Ni3Al, and Al2O3. The hot corrosion resistance of AlO-CrO/NiCoCrAlYTa coating is better than that of AlO/NiCoCrAlYTa coating. This improvement is attributed to lower porosity and more compact Cr2O3 in AlO-CrO/NiCoCrAlYTa coating which performs better than Al2O3 in blocking further inward progress of corrosion and oxidization.

  20. Kerr effect enhancement and corrosion resistance improvement by AlN and AlSiN films (abstract)

    NASA Astrophysics Data System (ADS)

    Lee, Z. Y.; Miao, X. S.; Liu, X. J.; Lin, G. Q.; Wan, D. F.; Hu, Y. S.

    1990-05-01

    RE-TM amorphous thin films with perpendicular magnetic anisotropy are promising for use in erasable optical recording media. In order to improve the drawback of easy oxidation and lower C/N of RE-TM films, some protective layers such as SiO, SiO2, ZnS, AlN, and Si3N4 films were studied.1,2 We have studied the Kerr effect enhancement and corrosion resistance improvement by AlN and AlSiN films. AlN and AlSiN films were prepared on glass, PC, and PMMA substrates by a rf magnetron sputtering system with three targets using low sputtering power. The films have a high refractive index (2-2.15), high optical transparency (over 90%), and high stability. The relation between optical properties and rf reactive sputtering conditions (Ar: N2 ratio, total pressure, sputtering power, sputtering time), composition, spectral transmittance, and uniformity of sputtering AlN and AlSiN films were studied. The Kerr rotation angle was up to 1.5° in AlN/TbFeCo/glass and AlSiN/TbFeCo/glass multilayer structures (laser is incident from air). We also studied AlN/TbFeCo/AlN/glass, AlN/TbFeCo/AlN/Al/glass, AlSiN/TbFeCo/AlSiN/glass and multilayer structure films. The results show that AlN and AlSiN films provide sufficient Kerr effect enhancement and superior corrosion resistance improvement to the RE-TM films. The microstructure of those films were also studied by JEM, XRD, and XPS.

  1. Theory and X-ray Absorption Spectroscopy for Aluminum Coordination Complexes – Al K-Edge Studies of Charge and Bonding in (BDI)Al, (BDI)AlR2, and (BDI)AlX2 Complexes.

    PubMed

    Altman, Alison B; Pemmaraju, C D; Camp, Clément; Arnold, John; Minasian, Stefan G; Prendergast, David; Shuh, David K; Tyliszczak, Tolek

    2015-08-19

    Polarized aluminum K-edge X-ray absorption near edge structure (XANES) spectroscopy and first-principles calculations were used to probe electronic structure in a series of (BDI)Al, (BDI)AlX2, and (BDI)AlR2 coordination compounds (X = F, Cl, I; R = H, Me; BDI = 2,6-diisopropylphenyl-β-diketiminate). Spectral interpretations were guided by examination of the calculated transition energies and polarization-dependent oscillator strengths, which agreed well with the XANES spectroscopy measurements. Pre-edge features were assigned to transitions associated with the Al 3p orbitals involved in metal-ligand bonding. Qualitative trends in Al 1s core energy and valence orbital occupation were established through a systematic comparison of excited states derived from Al 3p orbitals with similar symmetries in a molecular orbital framework. These trends suggested that the higher transition energies observed for (BDI)AlX2 systems with more electronegative X(1-) ligands could be ascribed to a decrease in electron density around the aluminum atom, which causes an increase in the attractive potential of the Al nucleus and concomitant increase in the binding energy of the Al 1s core orbitals. For (BDI)Al and (BDI)AlH2 the experimental Al K-edge XANES spectra and spectra calculated using the eXcited electron and Core-Hole (XCH) approach had nearly identical energies for transitions to final state orbitals of similar composition and symmetry. These results implied that the charge distributions about the aluminum atoms in (BDI)Al and (BDI)AlH2 are similar relative to the (BDI)AlX2 and (BDI)AlMe2 compounds, despite having different formal oxidation states of +1 and +3, respectively. However, (BDI)Al was unique in that it exhibited a low-energy feature that was attributed to transitions into a low-lying p-orbital of b1 symmetry that is localized on Al and orthogonal to the (BDI)Al plane. The presence of this low-energy unoccupied molecular orbital on electron-rich (BDI)Al distinguishes

  2. Investigation of etching techniques for superconductive Nb/Al-Al2O3/Nb fabrication processes

    NASA Technical Reports Server (NTRS)

    Lichtenberger, A. W.; Lea, D. M.; Lloyd, F. L.

    1993-01-01

    Wet etching, CF4 and SF6 reactive ion etching (RIE), RIE/wet hybrid etching, Cl-based RIE, ion milling, and liftoff techniques have been investigated for use in superconductive Nb/Al-Al2O3/Nb fabrication processes. High-quality superconductor-insulator-superconductor (SIS) junctions have been fabricated using a variety of these etching methods; however, each technique offers distinct tradeoffs for a given process an wafer design. In particular, it was shown that SF6 provides an excellent RIE chemistry for low-voltage anisotropic etching of Nb with high selectivity to Al. The SF6 tool has greatly improved the trilevel resist junction insulation process. Excellent repeatability, selectivity with respect to quartz, and submicron resolution make Cl2 + BCl3 + CHCl3 RIE a very attractive process for trilayer patterning.

  3. FUV Reflectance of Recently Prepared Al Protected with AlF3: COR Program Technology Development

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel

    2016-01-01

    Astronomical observations in the Far Ultraviolet (FUV) spectral region are some of the more challenging due to the very distant and faint objects that are typically searched for in cosmic origin studies such as origin of large scale structure, the formation, evolution, and age of galaxies and the origin of stellar and planetary systems. These challenges are driving the need to improve the performance of optical coatings over a wide spectral range that would increase reflectance in mirrors and reduced absorption in dielectric filters used in optical telescope for FUV observations. This paper will present recent advances in reflectance performance for Al+AlF3 mirrors optimized for Lyman-alpha wavelength by performing the deposition of the AlF3 overcoat at elevated substrate temperatures.

  4. Compressive strength of directionally solidified NiAl-NiAlNb intermetallics at 1200 and 1300 K

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Reviere, R.; Noebe, R. D.; Oliver, B. F.

    1992-01-01

    Results are presented from measurements of 1200 K and 1300 K compressive properties of two directionally solidified NiAl-NiAlNb compositions (in at. pct): Ni-41.75Al-16.5Nb (eutectic composition) and Ni-47.5Al-8.9Nb-1.3C (Al-rich composition). Results showed that the strength of the eutectic was a factor of 2 greater than that of the Al-rich composition. However, the analysis of the compressive stress-strain data indicated that the deformation mechanism was the same in both materials.

  5. Acoustic resonator with Al electrodes on an AlN layer and using a GaAs substrate

    DOEpatents

    Kline, Gerald R.; Lakin, Kenneth M.

    1985-12-03

    A method of fabricating an acoustic wave resonator wherein all processing steps are accomplished from a single side of said substrate. The method involves deposition of a multi-layered Al/AlN structure on a GaAs substrate followed by a series of fabrication steps to define a resonator from said composite. The resulting resonator comprises an AlN layer between two Al layers and another layer of AlN on an exterior of one of said Al layers.

  6. Cysteine Modifications in the Pathogenesis of ALS

    PubMed Central

    Valle, Cristiana; Carrì, Maria Teresa

    2017-01-01

    Several proteins are found misfolded and aggregated in sporadic and genetic forms of amyotrophic lateral sclerosis (ALS). These include superoxide dismutase (SOD1), transactive response DNA-binding protein (TDP-43), fused in sarcoma/translocated in liposarcoma protein (FUS/TLS), p62, vasolin-containing protein (VCP), Ubiquilin-2 and dipeptide repeats produced by unconventional RAN-translation of the GGGGCC expansion in C9ORF72. Up to date, functional studies have not yet revealed a common mechanism for the formation of such diverse protein inclusions. Consolidated studies have demonstrated a fundamental role of cysteine residues in the aggregation process of SOD1 and TDP43, but disturbance of protein thiols homeostatic factors such as protein disulfide isomerases (PDI), glutathione, cysteine oxidation or palmitoylation might contribute to a general aberration of cysteine residues proteostasis in ALS. In this article we review the evidence that cysteine modifications may have a central role in many, if not all, forms of this disease. PMID:28167899

  7. CarbAl Heat Transfer Material

    NASA Technical Reports Server (NTRS)

    Fink, Richard

    2015-01-01

    The increasing use of power electronics, such as high-current semiconductor devices and modules, within space vehicles is driving the need to develop specialty thermal management materials in both the packaging of these discrete devices and the packaging of modules consisting of these device arrays. Developed by Applied Nanotech, Inc. (ANI), CarbAl heat transfer material is uniquely characterized by its low density, high thermal diffusivity, and high thermal conductivity. Its coefficient of thermal expansion (CTE) is similar to most power electronic materials, making it an effective base plate substrate for state-of-the-art silicon carbide (SiC) super junction transistors. The material currently is being used to optimize hybrid vehicle inverter packaging. Adapting CarbAl-based substrates to space applications was a major focus of the SBIR project work. In Phase I, ANI completed modeling and experimentation to validate its deployment in a space environment. Key parameters related to cryogenic temperature scaling of CTE, thermal conductivity, and mechanical strength. In Phase II, the company concentrated on improving heat sinks and thermally conductive circuit boards for power electronic applications.

  8. TBK1 is associated with ALS and ALS-FTD in Sardinian patients.

    PubMed

    Borghero, Giuseppe; Pugliatti, Maura; Marrosu, Francesco; Marrosu, Maria Giovanna; Murru, Maria Rita; Floris, Gianluca; Cannas, Antonino; Occhineri, Patrizia; Cau, Tea B; Loi, Daniela; Ticca, Anna; Traccis, Sebastiano; Manera, Umberto; Canosa, Antonio; Moglia, Cristina; Calvo, Andrea; Barberis, Marco; Brunetti, Maura; Gibbs, J Raphael; Renton, Alan E; Errichiello, Edoardo; Zoledziewska, Magdalena; Mulas, Antonella; Qian, Yong; Din, Jun; Pliner, Hannah A; Traynor, Bryan J; Chiò, Adriano

    2016-07-01

    Recently, mutations in the TANK-binding kinase 1 (TBK1) gene were identified as a cause for amyotrophic lateral sclerosis (ALS) with or without comorbid frontotemporal dementia. We have assessed the frequency and clinical characteristics of TBK1 mutations in a cohort of ALS patients of Sardinian ancestry. Whole-exome sequencing was performed on Hiseq2000 platform (Illumina). Genome analysis Toolkit was used to align and to code variants according to Human Genome (UCSC hg19). Mutation was confirmed with Sanger sequence. In our screening of 186 Sardinian ALS cases, we found 3 (1.6%) patients carrying 3 distinct novel genetic variants: a nonsynonymous SNV c.1150C>T leading to a p.Arg384Thr change in exon 9; a nonsynonymous SNV c.1331G>A causes a p.Arg444Gln change in exon 11; and a frameshift deletion c.2070delG (p.Met690fs) at the exon 20 of the gene leading to a stop at 693 codon. The latter patients also carried missense mutation c.98C>T of the SQSTM1 gene causing a substitution of an arginine with a valine at the position 33 (p.Arg33Val). All variants were found to be deleterious according to in silico predictions. All cases were apparently sporadic and one of them showed frontotemporal dementia associated to ALS. These mutations were not found in 2 cohorts of 6780 ethnic-matched controls. We have found that TBK1 mutations account for 1.6% of Sardinian ALS cases. Our data support the notion that TBK1 is a novel ALS gene, providing important evidence complementary to the first descriptions.

  9. Growth and photoluminescence characteristics of AlGaAs nanowires

    NASA Astrophysics Data System (ADS)

    Wu, Z. H.; Sun, M.; Mei, X. Y.; Ruda, H. E.

    2004-07-01

    Growth of high-quality single-crystal AlGaAs nanowires was demonstrated using the vapor-liquid-solid (VLS) mechanism with molecular-beam epitaxy (MBE). Highly ordered AlGaAs nanowire arrays and GaAs /AlGaAs multilayer nanowires were also prepared. Photoluminescence (PL) from homogeneous AlGaAs and GaAs /AlGaAs multilayer nanowires was measured. The Al composition of the AlGaAs nanowires was found to be significantly lower than that for planar MBE films grown under the same conditions, as determined from PL and energy-dispersive x-ray spectroscopy measurements. This is explained in terms of the different growth mechanisms for VLS and normal MBE. Such AlGaAs nanowires are expected to have a wide range of applications in electronic and photonic devices.

  10. Excitonic localization at macrostep edges in AlGaN/AlGaN multiple quantum wells

    NASA Astrophysics Data System (ADS)

    Hou, Mengjun; Qin, Zhixin; Zhang, Lisheng; Han, Tianyang; Wang, Mingxing; Xu, Fujun; Wang, Xinqiang; Yu, Tongjun; Fang, Zheyu; Shen, Bo

    2017-04-01

    Double peaks at wavelength of 276 and 290 nm are observed for AlGaN/AlGaN multiple quantum wells (MQWs). Cathodoluminescence (CL) mappings identify that the emission at 290 nm originates from the macrostep edges. Potential minima induced by local variation of QW thickness and Ga incorporation are found along the step edges, where quantum wires (QWRs) are formed. The lateral advance rate of macrostep (∼310 nm/h) is obtained by investigating the distribution of QWRs. Temperature-dependent CL spectrum suggest that thermal quenching for 290 nm emission is dramatically suppressed compared with that for conventional QWs emission, which shows excitonic localization characteristics of QWRs.

  11. Microstructure and Creep Properties of TiAl-Ti3Al In-Situ Composites

    SciTech Connect

    Hodge, A M; Hsiung, L L

    2004-02-18

    Objectives: {lg_bullet} Exploit thermomechanical-processing techniques to fabricate TiAl/Ti3Al in-situ laminate composites with the size of lamella width down to submicron or nanometer length-scales. {lg_bullet} Characterize microstructure and elevated-temperature creep resistance of the in-situ composites. {lg_bullet} Investigate the fundamental interrelationships among microstructures, alloying additions, and mechanical properties of the in-situ composites so as to achieve the desired properties of the in-situ composites for high-temperature structural applications.

  12. Vanishing quasiparticle density in a hybrid Al/Cu/Al single-electron transistor

    NASA Astrophysics Data System (ADS)

    Saira, O.-P.; Kemppinen, A.; Maisi, V. F.; Pekola, J. P.

    2012-01-01

    The achievable fidelity of many nanoelectronic devices based on superconducting aluminum is limited by either the density of residual nonequilibrium quasiparticles nqp or the density of quasiparticle states in the gap, characterized by Dynes parameter γ. We infer upper bounds nqp<0.033μm-3 and γ<1.6×10-7 from transport measurements performed on Al/Cu/Al single-electron transistors, improving previous results by an order of magnitude. Owing to efficient microwave shielding and quasiparticle relaxation, a typical number of quasiparticles in the superconducting leads is zero.

  13. Growth and Oxidation of Thin Film Al(2)Cu

    SciTech Connect

    SON,KYUNG-AH; MISSERT,NANCY A.; BARBOUR,J. CHARLES; HREN,J.J.; COPELAND,ROBERT GUILD; MINOR,KENNETH G.

    2000-01-18

    Al{sub 2}Cu thin films ({approx} 382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {micro} 3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30-70 {micro}m wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67 {+-} 2% Al and 33 {+-} 2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approx} 5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.

  14. Inferred Initial 26Al/27Al Ratios in Presolar Stardust Grains from Supernovae are Higher than Previously Estimated

    NASA Astrophysics Data System (ADS)

    Groopman, Evan; Zinner, Ernst; Amari, Sachiko; Gyngard, Frank; Hoppe, Peter; Jadhav, Manavi; Lin, Yangting; Xu, Yuchen; Marhas, Kuljeet; Nittler, Larry R.

    2015-08-01

    We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si3N4 grains found to contain large excesses of 26Mg, indicative of the initial presence of live 26Al. Ninety of the more than 450 presolar grains processed in this study contain well-correlated {δ }26{Mg}{/}24{Mg} and 27Al/24Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial {}26{Al}{/}27{Al} ratios that, on average, are ˜1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative {δ }26{Mg}{/}24{Mg} intercepts of the isochron lines. Al contamination is potentially due to etching of the grains’ surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial {}26{Al}{/}27{Al} ratios. The presolar grains with the highest {}26{Al}{/}27{Al} ratios are from Type II supernovae whose isochron-derived initial {}26{Al}{/}27{Al} ratios greatly exceed those predicted in the He/C and He/N zones of SN models.

  15. Simulation Study of Al-1Mn/Al-10Si Circular Clad Ingots Prepared by Direct Chill Casting

    NASA Astrophysics Data System (ADS)

    Wu, Li; Kang, Huijun; Chen, Zongning; Fu, Ying; Wang, Tongmin

    2016-02-01

    A modified direct chill casting process based on Novelis FusionTM Technology co-casting process was used recently to prepare Al-1Mn/Al-10Si circular clad ingots. In the current study, a comprehensive simulation model was developed to investigate the direct chill casting process for preparing the Al-1Mn/Al-10Si circular clad ingots, and a parametric study and experimental research of the direct chill casting process was conducted to explore potential success and failure casting conditions. The simulation results revealed the bonding mechanism of the Al-1Mn/Al-10Si interface in the direct chill casting process and identified the effect of certain parameters on casting performance. The results indicated that the effect of casting speed and Al-1Mn casting temperature on the variations of the minimum solid fraction of Al-1Mn at the interface is stronger than that of cooling water flow rate in inner mold, while Al-10Si casting temperature is the weakest of the four casting parameters. The corresponding experimental results verified that Al-1Mn/Al-10Si circular clad ingot with acceptable metallurgical bonding can be successfully prepared by direct chill casting process under the proper casting parameters. The thickness of diffusion zone is about 40 μm, and the fractured position in tensile test was located in the Al-1Mn alloy side which indicated the strength of the interfacial region is higher than that of Al-1Mn alloy.

  16. Effect of Al Doping on Optical Band Gap Energy of Al-TiO2 Thin Films.

    PubMed

    Song, Yo-Seung; Kim, Bae-Yeon; Cho, Nam-Ihn; Lee, Deuk Yong

    2015-07-01

    Al-TiO2 thin films were prepared using a sol-gel derived spin coating by varying the Al/Ti molar ratio from 0 to 0.73 to investigate the effect of Al doping on the optical band gap energy (Eg) of the films. GAXRD results indicated that Al-TiO2 is composed of anatase and FTO phases when the Al/Ti molar ratio was less than 0.18. Above 0.38, no other peaks except FTO were found and transparency of the films was severely deteriorated. Eg of Al-TiO2 decreased from 3.20 eV to 2.07 eV when the Al/Ti ratio was raised from 0 to 0.38. Eg of 2.59 eV was found for the anatase Al-TiO2 films having the Al/Ti ratio of 0.18. The absorption band of Al-TiO2 coatings shifted dramatically from the UV region to the visible region with increasing the amount of Al dopant. The Al doping was mainly attributed to the optical band gap energy of Al-TiO2.

  17. Comparison on the interaction of Al3+/nano-Al13 with calf thymus DNA /salmon sperm DNA

    NASA Astrophysics Data System (ADS)

    Ma, Fei; Ma, Yue; Du, Changwen; Yang, Xiaodi; Shen, Renfang

    2015-11-01

    The conformation change, binding mode and binding site between Al3+/nano-Al13 and calf thymus DNA/salmon sperm DNA were investigated by UV-vis absorption, FTIR spectra, Raman spectroscopy and CD spectra, as well as melting curves measurement. The UV-vis spectra and circular dichroism spectra results suggested that the phosphate group structure was changed when Al3+ interacted with DNA, while the double-helix was distorted when nano-Al13 interacted with DNA. The FTIR and Raman spectroscopy revealed that the binding sites were Al3+ … PO2, Al3+ … N7/guanine PO2 … Al13 … N7-C8/guanine with calf thymus DNA, and Al3+ … N3-O2/cytosine, Al3+ … N7-C8/guanine, PO2 … Al13 … N7-C8/guanine, PO2 … Al13 … N1/adenine with salmon sperm DNA, respectively. The electrostatic binding was existed between Al3+ and DNA, and the electrostatic binding and complexing were found between nano-Al13 and DNA.

  18. Effect of Al on the Wetting Behavior Between TiC x and Molten Ti-Al Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Xuyang; Lv, Xuewei; Dong, Hongbiao; Li, Chunxin; Bai, Chenguang

    2015-10-01

    The wetting behavior and the interfacial reactions between TiC x substrate and molten Ti-Al alloys with different Al contents were studied using the Sessile Drop method at 1758 K (1485 °C) in argon atmosphere. It is found that the wettability and interface reaction products depend on Al content in the molten alloy. The initial contact angles between the molten Ti-Al alloy and TiC0.78 surface reduces from 110 to 80 deg when Al content in the alloy changes from 40 to 80 wt pct. The reduction in the initial contact angle is due to the decrease of surface tension of the molten Ti-Al alloys with increasing Al contents. The segregation of Al atoms to the surface occurred at all bulk concentrations of Ti-Al alloys. Al with lower surface tension tends to segregate on the surface of liquid Ti-Al alloy. In the spreading stage, the interfacial reaction led to the decrease in the contact angle. The adhesion in Ti-Al/TiC x system can be interpreted in terms of strong chemical interactions, which is greatly affected by the diffusion of C. The equilibrium contact angle was measured less than 10 deg. Finally, the reaction sequence at the Ti-Al melt and TiC x substrate interface is proposed.

  19. Effect of a grain refiner cum modifier on mechanical properties of Al-7Si and Al-11Si alloys

    NASA Astrophysics Data System (ADS)

    Jigajinni, S. M.; Venkateswarlu, K.; Kori, S. A.

    2013-03-01

    This study evaluates the influence of grain refiners/modifiers on the mechanical properties of the Al-7Si and Al-11Si alloys with an experiment of quantitative and qualitative correlations with the microstructure. Modification of Al-Si alloys with strontium additions and grain refinement with Al-Ti, Al-B and Al-T-B master alloy additions are demonstrated to be efficient on Al-Si alloys. A single master alloy with combined additions of Sr and Ti and/or B was prepared and the microstructure and mechanical properties were studied. The results show that boron rich (Al-3B-Sr and Al-1Ti-3B-Sr) master alloys are more efficient than Ti rich (Al-3Ti-Sr and Al-5Ti-1B-Sr) master alloys considering their combined grain refinement and modification effect on Al-7Si and Al-11Si alloys. However, the presence of Sr does not influence the grain refinement. Similarly, presence of grain refiner does not influence the modification of eutectic Si.

  20. Mechanisms of elevated-temperature deformation in the B2 aluminides NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Yaney, D. L.; Nix, W. D.

    1988-01-01

    A strain rate change technique, developed previously for distinguishing between pure-metal and alloy-type creep behavior, was used to study the elevated-temperature deformation behavior of the intermetallic compounds NiAl and CoAl. Tests on NiAl were conducted at temperatures between 1100 and 1300 K while tests on CoAl were performed at temperatures ranging from 1200 to 1400 K. NiAl exhibits pure-metal type behavior over the entire temperature range studied. CoAl, however, undergoes a transition from pure-metal to alloy-type deformation behavior as the temperature is decreased from 1400 to 1200 K. Slip appears to be inherently more difficult in CoAl than in NiAl, with lattice friction effects limiting the mobility of dislocations at a much higher tmeperature in CoAl than in NiAl. The superior strength of CoAl at elevated temperatures may, therefore, be related to a greater lattice friction strengthening effect in CoAl than in NiAl.

  1. Motor neuron death in ALS – programmed by astrocytes?

    PubMed Central

    Pirooznia, Sheila K.; Dawson, Valina L.; Dawson, Ted M.

    2014-01-01

    Motor neurons in ALS die via cell-autonomous and non-cell autonomous mechanisms. Using adult human astrocytes and motor neurons, Re et al (2014) discover that familial and sporadic ALS derived human adult astrocytes secrete neurotoxic factors that selectively kill motor neurons through necroptosis, suggesting a new therapeutic avenue. PMID:24607221

  2. 77 FR 67689 - Fidelity Aberdeen Street Trust, et al.;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... COMMISSION Fidelity Aberdeen Street Trust, et al.; Notice of Application November 6, 2012. AGENCY: Securities... certain joint arrangements (``Prior Order'').\\1\\ \\1\\ Colchester Street Trust, et al., Investment Company..., Colchester Street Trust, et al., Investment Company Act Release Nos. 23787 (Apr. 15, 1999) (notice) and...

  3. 77 FR 45238 - Amendment of Class E Airspace; Montgomery, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-31

    ... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Montgomery, AL AGENCY... amends Class E Airspace in the Montgomery, AL area, by recognizing the name change of Prattville-Grouby... Federal Regulations (14 CFR) part 71 amends Class E airspace for the Montgomery, AL, area at the...

  4. 76 FR 80232 - Establishment of Class E Airspace; Oneonta, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-23

    ... Airspace; Oneonta, AL AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action establishes Class E Airspace at Oneonta, AL, to accommodate the new Area Navigation (RNAV) Global... establish Class E airspace at Oneonta, AL (76 FR 58728) Docket No. FAA-2011-0744. Interested parties...

  5. 77 FR 40265 - Drawbridge Operation Regulation; Tennessee River, Decatur, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-09

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Tennessee River, Decatur, AL AGENCY... across the Tennessee River, mile 304.4, at Decatur, AL. The deviation is necessary to install new rail..., at Decatur, AL. The vertical clearance of the bridge in the closed position is 10.5 feet. The...

  6. The Resurgence of Al-Qaeda in Syria and Iraq

    DTIC Science & Technology

    2014-05-01

    also spelled Al Julani). His name reflects the fact that he is probably from the Golan Heights, and is thought to have close 28 ties to Abu Musab al... ancient city of Aleppo in the northwest. The group’s social wing, Qism al-Ighatha (Relief Department), provides food and warm clothing to civilians

  7. Electronic and vibrational properties of γ-AlH3

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Yan, Jia-An; Chou, M. Y.

    2008-01-01

    Aluminum hydride (alane) AlH3 is an important material in hydrogen storage applications. It is known that AlH3 exists in multiply forms of polymorphs, where α-AlH3 is found to be the most stable with a hexagonal structure. Recent experimental studies on γ-AlH3 reported an orthorhombic structure with a unique double-bridge bond between certain Al and H atoms. This was not found in α-AlH3 or other polymorphs. Using density functional theory, we have investigated the energetics, and the structural, electronic, and phonon vibrational properties for the newly reported γ-AlH3 structure. The current calculation concludes that γ-AlH3 is less stable than α-AlH3 by 1.2KJ/mol , with the zero-point energy included. Interesting binding features associated with the unique geometry of γ-AlH3 are discussed from the calculated electronic properties and phonon vibrational modes. The binding of H-s with higher energy Al-p,d orbitals is enhanced within the double-bridge arrangement, giving rise to a higher electronic energy for the system. Distinguishable new features in the vibrational spectrum of γ-AlH3 were attributed to the double-bridge and hexagonal-ring structures.

  8. MCrAlY bond coat with enhanced Yttrium layer

    DOEpatents

    Jablonski, Paul D; Hawk, Jeffrey A

    2015-04-21

    One or more embodiments relates to an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y--Al oxides, providing advantage in the maintainability of the Yttrium reservoir within the MCrAlY bulk. The MCrAlY bond coat may be fabricated through application of a Y.sub.2O.sub.3 paste to an MCrAlY material, followed by heating in a non-oxidizing environment.

  9. To Ponder Ponderal's Length: A Question to Lester et. al.

    ERIC Educational Resources Information Center

    Scanlon, John W.

    1984-01-01

    Criticizes Lester, Als, and Brazelton's 1982 reanalysis of data presented by Scanlon, Nelson, Grylack, and Smith in 1979. Discusses (1) clinical interpretation of the ponderal index (a weight-for-length ratio); and (2) inaccurate measurement of crown-heel length; (3) Lester et al.'s suggested relationship between the ponderal index, maternal drug,…

  10. LaRhAl, La3Rh3Al4, and Ce5Rh5Al6 as a new family of ternary aluminides

    NASA Astrophysics Data System (ADS)

    Avzuragova, V. A.; Nesterenko, S. N.; Tursina, A. I.

    2017-02-01

    The structures of three aluminides of similar composition are determined via X-ray diffraction. The structures consist of coordination polyhedra built of rhodium atoms that form alternating layers extending perpendicular to the short cell parameter. Compound Ce5Rh5Al6 is built of fragments of the structures of LaRhAl and La3Rh3Al4 in a ratio of 1: 1.

  11. Screw dislocation-induced growth spirals as emissive exciton localization centers in Al-rich AlGaN/AlN quantum wells

    SciTech Connect

    Funato, Mitsuru Banal, Ryan G.; Kawakami, Yoichi

    2015-11-15

    Screw dislocations in Al-rich AlGaN/AlN quantum wells cause growth spirals with an enhanced Ga incorporation, which create potential minima. Although screw dislocations and their surrounding potential minima suggest non-radiative recombination processes within growth spirals, in reality, screw dislocations are not major non-radiative sinks for carriers. Consequently, carriers localized within growth spirals recombine radiatively without being captured by non-radiative recombination centers, resulting in intense emissions from growth spirals.

  12. U-Mo/Al-Si interaction: Influence of Si concentration

    NASA Astrophysics Data System (ADS)

    Allenou, J.; Palancher, H.; Iltis, X.; Cornen, M.; Tougait, O.; Tucoulou, R.; Welcomme, E.; Martin, Ph.; Valot, C.; Charollais, F.; Anselmet, M. C.; Lemoine, P.

    2010-04-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 °C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2Al 20, when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6Mo 4Al 43. For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3(Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2Al 20. On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

  13. Direct synthesis of nanoporous carbon nitride fibers using Al-based porous coordination polymers (Al-PCPs).

    PubMed

    Hu, Ming; Reboul, Julien; Furukawa, Shuhei; Radhakrishnan, Logudurai; Zhang, Yuanjian; Srinivasu, Pavuluri; Iwai, Hideo; Wang, Hongjing; Nemoto, Yoshihiro; Suzuki, Norihiro; Kitagawa, Susumu; Yamauchi, Yusuke

    2011-07-28

    We report a new synthetic route for preparation of nanoporous carbon nitride fibers with graphitic carbon nitride polymers, by calcination of Al-based porous coordination polymers (Al-PCPs) with dicyandiamide (DCDA) under a nitrogen atmosphere.

  14. Ab initio molecular dynamics of Al irradiation-induced processes during Al{sub 2}O{sub 3} growth

    SciTech Connect

    Music, Denis; Nahif, Farwah; Friederichsen, Niklas; Schneider, Jochen M.; Sarakinos, Kostas

    2011-03-14

    Al bombardment induced structural changes in {alpha}-Al{sub 2}O{sub 3} (R-3c) and {gamma}-Al{sub 2}O{sub 3} (Fd-3m) were studied using ab initio molecular dynamics. Diffusion and irradiation damage occur for both polymorphs in the kinetic energy range from 3.5 to 40 eV. However, for {gamma}-Al{sub 2}O{sub 3}(001) subplantation of impinging Al causes significantly larger irradiation damage and hence larger mobility as compared to {alpha}-Al{sub 2}O{sub 3}. Consequently, fast diffusion along {gamma}-Al{sub 2}O{sub 3}(001) gives rise to preferential {alpha}-Al{sub 2}O{sub 3}(0001) growth, which is consistent with published structure evolution experiments.

  15. Reduction in leakage current in AlGaN/GaN HEMT with three Al-containing step-graded AlGaN buffer layers on silicon

    NASA Astrophysics Data System (ADS)

    Yu, Xinxin; Ni, Jinyu; Li, Zhonghui; Zhou, Jianjun; Kong, Cen

    2014-05-01

    AlGaN/GaN high-electron-mobility transistor (HEMT) structures with two and three Al-containing step-graded AlGaN buffer layers (BLs) were grown on silicon (111) substrates by metal organic chemical vapor deposition. Considerable tensile stress was observed in the GaN grown with only two 0.8 µm AlGaN BLs, while a large in-plane compression in GaN grown with three 2.3 µm AlGaN BLs. The reverse gate leakage current in the HEMT with three AlGaN BLs was approximately 0.1 µA/mm, which was more than one order of magnitude smaller than that for the HEMT with two AlGaN BLs. A three-terminal off-state breakdown voltage of 265 V and a vertical gate-to-substrate breakdown voltage of 510 V were obtained in the HEMT with three AlGaN BLs. Detailed analysis was performed on the basis of the structural properties of AlGaN/GaN heterostructures.

  16. Cyclic Oxidation of FeCrAlY/Al2O3 Composites

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Draper, Susan L.; Barrett, Charles A.

    1999-01-01

    Three-ply FeCrAlY/Al2O3 composites and FeCrAlY matrix-only samples were cyclically oxidized at 1000 C and 1100 C for up to 1000 1-hr cycles. Fiber ends were exposed at the ends of the composite samples. Following cyclic oxidation, cracks running parallel to and perpendicular to the fibers were observed on the large surface of the composite. In addition, there was evidence of increased scale damage and spallation around the exposed fiber ends, particularly around the middle ply fibers. This damage was more pronounced at the higher temperature. The exposed fiber ends showed cracking between fibers in the outer plies, occasionally with Fe and Cr-rich oxides growing out of the cracks. Large gaps developed at the fiber/matrix interface around many of the fibers, especially those in the outer plies. Oxygen penetrated many of these gaps resulting in significant oxide formation at the fiber/matrix interface far within the composite sample. Around several fibers, the matrix was also internally oxidized showing Al2O3 precipitates in a radial band around the fibers. The results show that these composites have poor cyclic oxidation resistance due to the CTE mismatch and inadequate fiber/matrix bond strength at temperatures of 1000 C and above.

  17. Enhanced TC in granular and thin film Al-Al2O3 nanostructures

    NASA Astrophysics Data System (ADS)

    Higgins, J. S.; Greene, R. L.

    It is known since the 1970s that the superconducting transition temperature of granular aluminum films can be as high as two to three times the transition temperature of bulk aluminum, depending on the grain size and how strongly the nanometer size grains are connected1,2. As the strength of the grain connectivity becomes increasingly weak, the enhanced TC is suppressed. The mechanism behind this enhancement is still under debate. Recently, work on larger aluminum nanoparticles (18nm) embedded in an insulating Al2O3 matrix showed an onset of the superconducting transition as high as three times that of bulk aluminum3. In this situation, the Al grains are electrically disconnected and in a regime far removed from that of the granular films. Here we compare the two situations through electronic and thermal measurements in order to help elucidate the mechanism behind the enhancements. 1S. Pracht, et al., arXiv:1508.04270v1 [cond-mat.supr-con] (2015). 2G. Deutscher, New Superconductors From Granular to High TC, New Jersey: World Scientific, 2006, p. 72-74. 3V. N. Smolyaninova, et al., Sci. Rep. 5, 15777 (2015). Funding by NSF DMR # 1410665.

  18. A sulfur segregation study of PWA 1480, NiCrAl, and NiAl alloys

    NASA Technical Reports Server (NTRS)

    Jayne, D. T.; Smialek, J. L.

    1993-01-01

    Some nickel based superalloys show reduced oxidation resistance from the lack of an adherent oxide layer during high temperature cyclic oxidation. The segregation of sulfur to the oxide-metal interface is believed to effect oxide adhesion, since low sulfur alloys exhibit enhanced adhesion. X ray Photoelectron Spectroscopy (XPS) was combined with an in situ sample heater to measure sulfur segregation in NiCrAl, PWA 1480, and NiAl alloys. The polished samples with a 1.5 to 2.5 nm (native) oxide were heated from 650 to 1100 C with hold times up to 6 hr. The sulfur concentration was plotted as a function of temperature versus time at temperature. One NiCrAl sulfur study was performed on the same casting used by Browning to establish a base line between previous Auger Electron Spectroscopy (AES) results and the XPS results of this study. Sulfur surface segregation was similar for PWA 1480 and NiCrAl and reached a maximum of 30 at% at 800 to 850 C. Above 900 C the sulfur surface concentration decreased to about 3 at% at 1100 C. These results are contrasted to the minimal segregation observed for low sulfur hydrogen annealed materials which exhibit improved scale adhesion.

  19. High Temperature Mechanical Characterization and Analysis of Al2O3 /Al2O3 Composition

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Jaskowiak, Martha H.

    1999-01-01

    Sixteen ply unidirectional zirconia coated single crystal Al2O3 fiber reinforced polycrystalline Al2O3 was tested in uniaxial tension at temperatures to 1400 C in air. Fiber volume fractions ranged from 26 to 31%. The matrix has primarily open porosity of approximately 40%. Theories for predicting the Young's modulus, first matrix cracking stress, and ultimate strength were applied and evaluated for suitability in predicting the mechanical behavior of Al2O3/Al2O3 composites. The composite exhibited pseudo tough behavior (increased area under the stress/strain curve relative to monolithic alumina) from 22 to 1400 C. The rule-of-mixtures provides a good estimate of the Young's modulus of the composite using the constituent properties from room temperature to approximately 1200 C for short term static tensile tests in air. The ACK theory provides the best approximation of the first matrix cracking stress while accounting for residual stresses at room temperature. Difficulties in determining the fiber/matrix interfacial shear stress at high temperatures prevented the accurate prediction of the first matrix cracking stress above room temperature. The theory of Cao and Thouless, based on Weibull statistics, gave the best prediction for the composite ultimate tensile strength.

  20. Electronic transport through Al/InN nanowire/Al junctions

    SciTech Connect

    Lu, Tzu -Ming; Wang, George T.; Pan, Wei; Zhao, S.; Mi, Z.

    2016-02-10

    We report non-linear electronic transport measurement of Al/Si-doped n-type InN nanowire/Al junctions performed at T = 0.3 K, below the superconducting transition temperature of the Al electrodes. The proximity effect is observed in these devices through a strong dip in resistance at zero bias. In addition to the resistance dip at zero bias, several resistance peaks can be identified at bias voltages above the superconducting gap of the electrodes, while no resistance dip is observed at the superconducting gap. The resistance peaks disappear as the Al electrodes turn normal beyond the critical magnetic field except one which remains visible at fields several times higher than critical magnetic field. An unexpected non-monotonic magnetic field dependence of the peak position is observed. As a result, we discuss the physical origin of these observations and propose that the resistance peaks could be the McMillan-Rowell oscillations arising from different closed paths localized near different regions of the junctions.

  1. Electronic transport through Al/InN nanowire/Al junctions

    DOE PAGES

    Lu, Tzu -Ming; Wang, George T.; Pan, Wei; ...

    2016-02-10

    We report non-linear electronic transport measurement of Al/Si-doped n-type InN nanowire/Al junctions performed at T = 0.3 K, below the superconducting transition temperature of the Al electrodes. The proximity effect is observed in these devices through a strong dip in resistance at zero bias. In addition to the resistance dip at zero bias, several resistance peaks can be identified at bias voltages above the superconducting gap of the electrodes, while no resistance dip is observed at the superconducting gap. The resistance peaks disappear as the Al electrodes turn normal beyond the critical magnetic field except one which remains visible atmore » fields several times higher than critical magnetic field. An unexpected non-monotonic magnetic field dependence of the peak position is observed. As a result, we discuss the physical origin of these observations and propose that the resistance peaks could be the McMillan-Rowell oscillations arising from different closed paths localized near different regions of the junctions.« less

  2. Aesthetic Leadership (AL): Development and Implementation of Aesthetic Leadership Scale (ALS) of the School Directors

    ERIC Educational Resources Information Center

    Polat, Soner; Oztoprak-Kavak, Zehra

    2011-01-01

    This study aims to develop a scale for measuring the aesthetic leadership (AL) characteristics of the school directors and to show that it can be applicable. The population of the study is composed of the teachers who are on duty in the elementary, secondary and high schools located in Izmit, Kocaeli. Sample of this descriptive study comprises 400…

  3. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

    2009-06-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

  4. Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

    SciTech Connect

    Cherepanova, Svetlana V.; Leont’eva, Natalya N.; Arbuzov, Aleksey B.; Drozdov, Vladimir A.; Belskaya, Olga B.; Antonicheva, Nina V.

    2015-05-15

    Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl{sub 2}O{sub 4}. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl{sub 2}O{sub 4} structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-, UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al{sup 3+} ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al{sup 3+} ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/on the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides.

  5. An elliptical wiggler beamline for the ALS

    SciTech Connect

    Martynov, V.V. |; McKinney, W.R.; Padmore, H.A.

    1995-10-01

    A beamline for circularly polarized radiation produced by an elliptical wiggler has been designed at the ALS covering the broad energy range from 50 eV to 2000 eV. The rigorous theory of grating diffraction efficiency has been used to maximize transmitted flux. The nature of the elliptical wiggler insertion device creates a challenging optical problem due to the large source size in the vertical and horizontal directions. The requirement of high resolving power, combined with the broad tuning range and high heat loads complicate the design. These problems have been solved by using a variable included angle monochromator of the ``constant length`` type with high demagnification onto its entrance slit, and cooled optics.

  6. AlNb-Based Titanium Aluminide

    NASA Astrophysics Data System (ADS)

    Zhang, Kezhao; Liu, Ming; Lei, Zhenglong; Chen, Yanbin

    2014-10-01

    The microstructure of laser-tungsten inert gas hybrid welded Ti2AlNb-based joints and their tensile properties at room temperature were investigated in this paper. The results showed that good-quality joints could be obtained by hybrid welding process. The microstructure evolution was identified by means of optical microscopy, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The fusion zone mainly consisted of B2 phase due to the rapid cooling rate, as well as high Nb content. The phase compositions of the heat-affected zone were varied with different thermal cycles during the welding process. Tensile tests at room temperature showed that fracture tended to occur in the fusion zone, and the tensile strength and elongation were 950 MPa and 4.3%, respectively. The fracture mode was quasi-cleavage based on the observation of the fracture morphology.

  7. Al Eskan disease: Desert Storm pneumonitis.

    PubMed

    Korényi-Both, A L; Korényi-Both, A L; Molnár, A C; Fidelus-Gort, R

    1992-09-01

    The authors observed an acute desert-related disease when the mixture of the fine Saudi sand dust and pigeon droppings triggered a hyperergic lung condition. It was further aggravated by various kinds of organic pathogenic components contributing to an opportunistic infection of the lung. These all lead to the recognition of a new clinicopathological entity, Desert Storm pneumonitis or Al Eskan disease. For the first time, the Saudi sand dust's elemental composition was studied by ultrastructural and microanalytical means. The authors concluded that, contrary to previous beliefs, sand particles less than 1 microns (0.1 microns to 0.25 microns) in diameter are present in substantial quantities in the Saudi sand and are pathogenic, causing hyperergia. Pathogenesis of the sand dust, induced hyperergia, and its immunopathologic background are highlighted.

  8. In situ investigation of spinodal decomposition in hypermonotectic Al Bi and Al Bi Zn alloys

    NASA Astrophysics Data System (ADS)

    Schaffer, P. L.; Mathiesen, R. H.; Arnberg, L.; Di Sabatino, M.; Snigirev, A.

    2008-05-01

    Spinodal decomposition of hypermonotectic Al-6 wt.%Bi, Al-8 wt.%Bi and Al-6 wt.%Bi-8 wt.%Zn alloys has been investigated using synchrotron radiography. In the case of the 6 and 8 wt.%Bi binary alloys undercoolings of 70 and 110 K, respectively, were required to initiate the L→L1+L2 reaction, which appeared to occur very close to the monotectic reaction temperature. The nucleated L2 droplets were set in collective size-dependent motion by forces coupled to external fields (gravity and imposed temperature gradient) as well as forces arising due to internal fluctuations of the system. With experimental conditions similar to those realized during strip casting of the same materials, it was found that the size-dependant droplet velocity field combined with Stokes drag at the L1-L2 interfaces as well as attractive and repulsive diffusion-coupling between adjacent L2 droplets, yield complex meso- to microscale hydrodynamics. The hydrodynamics are the dominating mechanisms for L2 droplet coagulation, and are accordingly decisive for the final size distribution and geometrical dispersion of the soft Bi-rich component in the cast material. A different decomposition mode was observed in the Al-6 wt.%Bi-8 wt.%Zn ternary alloy, with the L2 droplets undergoing an immiscible-miscible-immiscible transition. In contrast to what was found for the binaries, L2 domains formed at relatively small undercoolings, and very little droplet motion was observed, as all L2 domains nucleated and remained on the crucible walls until they encroached on the monotectic front. At small distances from the monotectic front a Zn-rich solute boundary layer preceding the α-Al, caused the L2 domains to dissolve as Bi-Zn-Al regains complete miscibility upon reaching a critical Zn-concentration. In the shallow mush region behind the monotectic reaction, a high Zn solid solubility and a relatively fast diffusion of Zn in α-Al combine to cause a rapid diminishing Zn concentration in the mush liquid

  9. Successful Separationists in a Unity Fan Society: Al-Hirak Al-Janubi Social Movement in the Republic of Yemen

    DTIC Science & Technology

    2013-12-01

    regardless of the region, affiliation, gender , or status. 14. SUBJECT TERMS Al-Hirak Al-Janubi, Al-Houthies, Republic of Yemen, Ali Salem Al-Beedh, The...discrimination, and providing social services to its entire population regardless of the region, affiliation, gender , or status. vi THIS PAGE...and media until the occupation was forced to leave Aden. Just like their brothers in the North, the Southern revolutionaries made reunification of the

  10. Lattice gas hydrodynamics in two and three dimensions

    SciTech Connect

    Frisch, U.; d'Humieres, D.; Hasslacher, B.; Lallemand, P.; Pomeau, Y.; Rivet, J.P.

    1986-01-01

    Hydrodynamical phenomena can be simulated by discrete lattice gas models obeing cellular automata rules (U. Frisch, B. Hasslacher, and Y. Pomeau, Phys. Rev. Lett. 56, 1505, (1986); D. d'Humieres, P. Lallemand, and U. Frisch, Europhys. Lett. 2, 291, (1986)). It is here shown for a class of D-dimensional lattice gas models how the macrodynamical (large-scale) equations for the densities of microscopically conserved quantities can be systematically derived from the underlying exact ''microdynamical'' Boolean equations. With suitable restrictions on the crystallographic symmetries of the lattice and after proper limits are taken, various standard fluid dynamical equations are obtained, including the incompressible Navier-Stokes equations in two and three dimensions. The transport coefficients appearing in the macrodynamical equations are obtained using variants of fluctuation-dissipation and Boltzmann formalisms adapted to fully discrete situations.

  11. The Low-Lying States of AlCu and AlAg

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

    1994-01-01

    The singlet and triplet states of AlCu and AlAg below about 32 000/cm are studied using the internally contracted multireference configuration-interaction method. A more elaborate study of the X(sup 1)Sum(sup +) ground state of AlCu is undertaken using extended Gaussian basis sets, including the effect of inner-shell correlation and including a perturbational estimate of relativistic effects. Our best estimate of the spectroscopic constants (r(sub 0), DeltaG(sub 1/2), and D(sub 0)) for the X(sup 1)Sum(sup+) state with the experimental values in parentheses are: 4.416(4.420) a(sub 0), 295 (294) /cm, and 2.318 (2.315) eV. The calculations definitively assign the upper state in the observed transition at 14 892/cm to the lowest (sup 1)Prod state. The calculated spectroscopic constants and radiative lifetime for the (sup 1)Prod state are in good agreement with experiment. The calculations support the tentative assignments of Behm et al. for three band systems observed in the visible region between 25 000 and 28 000 / cm. However, the computed spectroscopic constants are in very poor agreement with those deduced from an analysis of the spectra. Analogous theoretical results for AlAg suggest that the (2)(sup 3)Prod, (3)(sup 3)Prod, and (3)(sup 1)Sum(sup +) states account for the bands observed, but not assigned, by Duncan and co-workers.

  12. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    PubMed Central

    Li, Jiehua; Hage, Fredrik S.; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-01-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption. PMID:27120994

  13. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys

    NASA Astrophysics Data System (ADS)

    Li, Jiehua; Hage, Fredrik S.; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-01

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP ‘patch’ dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  14. 77 FR 40492 - Revocation of Class D Airspace; Andalusia, AL; and Amendment of Class E Airspace; Fort Rucker, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-10

    ... Federal Aviation Administration 14 CFR Part 71 Revocation of Class D Airspace; Andalusia, AL; and Amendment of Class E Airspace; Fort Rucker, AL AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action removes Class D Airspace at Andalusia, AL, as the Air Traffic...

  15. Creep in Directionally Solidified NiAl-Mo Eutectics

    SciTech Connect

    Dudova, Marie; Kucharova, Kveta; Bartak, Tomas; Bei, Hongbin; George, Easo P; Somsen, Ch.; Dlouhy, A.

    2011-01-01

    A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.

  16. Diffusion Research in BCC Ti-Al-Mo Ternary Alloys

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Tang, Bin; Xu, Guanglong; Wang, Chuanyun; Kou, Hongchao; Li, Jinshan; Cui, Yuwen

    2014-04-01

    Interdiffusion in Ti-Al-Mo β solid solution was investigated at 1523 K (1250 °C) by analyzing diffusion couples. From the concentration profiles analytically represented by error function expansion (ERFEX), the ternary interdiffusion coefficients and impurity diffusivity were extracted by the Whittle-Green and generalized Hall methods. A comparison of the diffusion in five Ti-Al-X (Co, Cr, Fe, Mo, and V) ternaries reveals Ti-Al-Mo is comparably like Ti-Al-(Cr, V) while Ti-Al-(Co, Fe) are predominantly of interstitial nature.

  17. Strong adsorption of Al-doped carbon nanotubes toward cisplatin

    NASA Astrophysics Data System (ADS)

    Li, Wei; Li, Guo-Qing; Lu, Xiao-Min; Ma, Juan-Juan; Zeng, Peng-Yu; He, Qin-Yu; Wang, Yin-Zhen

    2016-08-01

    The adsorption of cisplatin molecule on Al-doped CNTs is investigated using density functional theory. The obtained results indicate that Al-doped carbon nanotubes can strongly absorb cisplatin. After absorbing cisplatin, the symmetry of CNTs has some changes. We innovatively defined a parameter of symmetry variation which relates to the adsorption. By analyzing the electronic structure, it can be concluded that under the circumstance that cisplatin was absorbed by Al-doped CNTs through aluminum atom of Al-doped CNTs. In conclusion, Al-doped CNTs is a kind of potential delivery carrier with high quality for anticancer drug cisplatin.

  18. Crystal structure of novel compounds in the systems Zr-Cu-Al, Mo-Pd-Al and partial phase equilibria in the Mo-Pd-Al system.

    PubMed

    Khan, Atta U; Rogl, P; Giester, G

    2012-02-28

    The crystal structures of three Al-rich compounds have been solved from X-ray single crystal diffractometry: τ(1)-MoPd(2-x)Al(8+x) (x = 0.067); τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) and τ(9)-ZrCu(1-x)Al(4) (x = 0.144). τ(1)-MoPd(2-x)Al(8+x) adopts a unique structure type (space group Pbcm; lattice parameters a = 0.78153(2), b = 1.02643(3) and c = 0.86098(2) nm), which can be conceived as a superstructure of the Mo(Cu(x)Al(1-x))(6)Al(4) type. Whereas Mo-atoms occupy the 4d site, Pd(2) occupies the 4c site, Al and Pd(1) atoms randomly share the 4d position and the rest of the positions are fully occupied by Al. A Bärnighausen tree documents the crystallographic group-subgroup relation between the structure types of Mo(Cu(x)Al(1-x))(6)Al(4) and τ(1). τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) has been confirmed to crystallize with the ThMn(12) type (space group I4/mmm; lattice parameters a = 0.85243(2) and c = 0.50862(3) nm). In total, 4 crystallographic sites were defined, out of which, Zr occupies site 2a, the 8f site is fully occupied by Cu, the 8i site is entirely occupied by Al, but the 8j site turned out to comprise a random mixture of Cu and Al atoms. The compound τ(9)-ZrCu(1-x)Al(4) (x = 0.144) crystallizes in a unique structure type (space group P4/nmm; lattice parameters a = 0.40275(3) and c = 1.17688(4) nm) which exhibits full atom order but a vacancy (14.4%) on the 2c site, shared with Cu atoms. τ(9)-ZrCu(1-x)Al(4) is a superstructure of Cu with an arrangement of three unit cells of Cu in the direction of the c-axis. A Bärnighausen tree documents this relationship. The ZrCu(1-x)Al(4) type (n = 3) is part of a series of structures which follow this building principle: Cu (n = 1), TiAl(3) (n = 2), τ(5)-TiNi(2-x)Al(5) (n = 4), HfGa(2) (n = 6) and Cu(3)Pd (n = 7). A partial isothermal section for the Al-rich part of the Mo-Pd-Al system at 860 °C has been established with two ternary compounds τ(1)-MoPd(2-x)Al(8+x) and τ(2) (unknown structure). The

  19. Thermoelectric properties of the Kondo insulator FeSb2

    NASA Astrophysics Data System (ADS)

    Figueira, M. S.; Silva-Valencia, J.; Franco, R.

    2012-06-01

    Recently it was shown [A. Bentien, S. Johnsen, G.K.H. Madsen, B.B. Iversen, F. Steglich, Europhys. Lett. 80, 17008 (2007)], that the strongly correlated Kondo insulator FeSb2 exhibits a colossal Seebeck coefficient; however, due to its large lattice thermal conductivity, the dimensionless thermoelectric figure of merit (zT) is only 0.005 at 12 K. This experimental result motivate us to perform a theoretical study of the thermoelectric properties of Kondo insulators, within the framework of the X-boson approach [R. Franco, M.S. Figueira, M.E. Foglio, Phys. Rev. B 66, 045112 (2002)] for the periodic Anderson model. We consider a set of parameters adequate for describing the compound FeSb2, and we calculate the resistivity, the thermoelectric power (Seebeck coefficient), the charge carrier thermal conductance, the thermoelectric factor power (zT), the Wiedemann-Franz law, the specific heat, and the Sommerfeld's γ coefficient. The result of the colossal maximum of the Seebeck coefficient, at low temperatures, has the same order of magnitude as the experimental result [A. Bentien, S. Johnsen, G.K.H. Madsen, B.B. Iversen, F. Steglich, Europhys. Lett. 80, 17008 (2007)]. We also show that those temperature region presents an intermediate valence behavior, characterized by a moderate increase of the Sommerfeld's γ coefficient.

  20. The immiscibility of InAlN ternary alloy

    PubMed Central

    Zhao, Guijuan; Xu, Xiaoqing; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Ji, Zesheng; Meng, Yulin; Wang, Lianshan; Yang, Shaoyan

    2016-01-01

    We have used two models based on the valence force field and the regular solution model to study the immiscibility of InAlN ternary alloy, and have got the spinodal and binodal curves of InAlN. Analyzing the spinodal decomposition curves, we obtain the appropriate concentration region for the epitaxial growth of the InN-AlN pseudobinary alloy. At a temperature most common for the epitaxial growth of InAlN (1000 K), the solubility of InN is about 10%. Then we introduce the mismatch strain item into the Gibbs free energy, and the effect of different substrates is taken into consideration. Considering Si, Al2O3, InN, GaN, AlN as a substrate respectively, it is found that all the five systems are stabilized with the upper critical solution temperature largely reduced. Finally, InN and GaN are potential substrates for In-rich InAlN, while AlN and GaN substrates are recommended in the Al-rich region. Si and Al2O3 may be ideal substrates for thin InAlN film. PMID:27221345