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Sample records for al eur phys

  1. Comment on ``Scattering length for fermionic alkali atoms". by S. Gautam and D. Angom, Eur. Phys. J. D 56, 173-179 (2010)

    NASA Astrophysics Data System (ADS)

    Ouerdane, H.; Jamieson, M. J.

    2010-04-01

    We suggest that Gautam and Angom [Eur. Phys. J. D 56, 173 (2010)] underestimated the influence of the van der Waals dispersion forces at long range on their calculated low energy scattering parameters and we provide numerical evidence in support. We also provide a simple proof of the relation between s-wave and p-wave scattering parameters and we comment briefly on the semiclassical formula derived by these authors.

  2. Comment on: Ab initio calculations of B2 type RHg (R = Ce,Pr,Eu and Gd) intermetallic compounds. Eur. Phys. J. B 87, 268 (2014), DOI: 10.1140/epjb/e2014-50521-6

    NASA Astrophysics Data System (ADS)

    Daoud, Salah

    2016-02-01

    In a recent article by Devi et al. [Eur. Phys. J. B 87, 268 (2014)], the structural, electronic, elastic and some thermal properties of B2 type RHg (R = Ce, Pr, Eu and Gd) intermetallic compounds have been studied by ab initio calculations. After the study of their article I found that there are some mistakes in predicted crystal density, longitudinal, transverse and average elastic wave velocities, and Debye temperature data. The crystal density has been found multiplied per 4. Also the longitudinal, transverse and average elastic wave velocities and Debye temperature are different from my reexamined values (all results represented by Devi et al. have been found divided per 2). Although these small mistakes do not influence their conclusion, it is better to correct them. In the present work, I reexamined all data again by using the right formulas, based on the lattice parameters and the elastic constants obtained in the work of Devi et al.

  3. Comment on: Measurement of the force exerted on the surface of an object immersed in a plasma. Eur. Phys. J. D 69: 91 (2015), DOI: 10.1140/epjd/e2015-50743-2

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe; Tsankov, Tsanko V.

    2015-10-01

    Surfaces exposed to a plasma experience a certain pressure that pushes them away from the volume. This effect has been investigated experimentally in a recent article by Thomas Trottenberg, Thomas Richter, and Holger Kersten from Kiel University/Germany [Eur. Phys. J. D 69, 91 (2015)]. The experimental results are impressive and have actually drawn the attention of the community to an interesting question which so far has been largely ignored. In addition to their experimental results the Kiel group proposes also a rough concept in order to explain their findings which provides certainly a basic qualitative understanding of the physical processes involved. However, on a closer inspection the picture developed so far is not entirely satisfying and the problem seems to require a more fundamental approach. This comment shows that the effect of the wall pressure can be described exactly using only analytical methods. The physical situation is analyzed by three different approaches. First, the simple case of only one spatial dimension is presented in detail. Second, the case of spherical symmetry is analyzed by some simplifying assumptions in order to investigate the effect of higher dimensionality. Third, a formal derivation for arbitrary geometry is given. This general result includes the one-dimensional case but does not allow a convenient connection between the pressures at the wall and in the center. Finally, the results are summarized and some conclusions are drawn.

  4. Comment on "Structural and Mössbauer studies of evaporated Fe100-x Pdx thin films" by A. Laggoun, A. Guittoum, S. Bahamida, M. Boudissa and A. Fnidiki. Eur. Phys. J. Appl. Phys. 68, 20301 (2014), Doi: 10.1051/epjap/2014140195

    NASA Astrophysics Data System (ADS)

    André Buffat, Philippe

    2016-03-01

    The paper "Structural and Mössbauer studies of evaporated Fe100-x Pdx thin films" by A. Laggoun et al. contains interpretation errors of XRD patterns and therefore cast some heavy doubt on the actual phases present in the Fe-Pd films.

  5. OBITUARY: Eur.Ing. Professor David Dew-Hughes in memoriam

    NASA Astrophysics Data System (ADS)

    Campbell, Archie; Dew-Hughes, Denise; Donaldson, Gordon; Palmer, Richard

    2007-06-01

    We regret to announce the death of David Dew-Hughes, the second Honorary Editor of Superconductor Science and Technology, in Autumn 2006. He was born in Manchester, the eldest of three children, attended Manchester Grammar School and took his first degree in metallurgy at Birmingham, before undertaking a Doctorate of Engineering at Yale University. After initial work for IBM on semiconductors, he returned to England as a lecturer in metallurgy at Cambridge University. There he devoted his career to superconductivity long before it became fashionable, starting a group on the properties of what we now know as type II materials, with his students Jan Evetts, Archie Campbell and Anant Narlikar. Between them they paved the way to our understanding of the magnetic vortex properties of these materials, and thus to the development of modern practical materials for superconducting magnets. Eur.Ing. Professor David Dew-Hughes 1932-2006 In 1965 he became a founding Senior Lecturer in physics at Lancaster University, moving to Brookhaven National Laboratory in 1974. His final academic post was in engineering science at Oxford University where he also held a University College Tutorial Fellowship. As long ago as 1971 David wrote an authoritative review for Reports on Progress in Physics on 'The metallurgical enhancement of type II superconductors'. Following the discovery of high-Tc superconductivity, IOP Publishing launched Superconductor Science and Technology in 1988 and he was a founder member of its Editorial Board. When Jan Evetts retired as Honorary Editor in 1992, David was the natural choice as his successor. He served a five year term and remained on the Board as Deputy Editor until the end of 2000. To mark the 10th anniversary of high-temperature superconductivity in 1997, David edited a special issue of Superconductor Science and Technology in which past and present members of the Editorial Board contributed reviews of their specialities. He noted that at that time

  6. Summary of PhysPAG Activity

    NASA Astrophysics Data System (ADS)

    Nousek, John A.

    2014-01-01

    The Physics of the Cosmos Program Analysis Group (PhysPAG) is responsible for solicitiing and coordinating community input for the development and execution of NASA's Physics of the Cosmos (PCOS) program. In this session I will report on the activity of the PhysPAG, and solicit community involvement in the process of defining PCOS objectives, planning SMD architecture, and prioritizing PCOS activities. I will also report on the activities of the PhysPAG Executive Committee, which include the chairs of the Science Analysis Groups/ Science Interest Groups which fall under the PhysPAG sphere of interest. Time at the end of the presentation willl be reserved for questions and discussion from the community.

  7. Summary of PhysPAG Activities

    NASA Astrophysics Data System (ADS)

    Ritz, Steven M.

    2013-01-01

    The Physics of the Cosmos (PCOS) Program Analysis Group (PhysPAG) provides an important interface between the scientific community and NASA in matters related to PCOS objectives, and also provides opportunities for community discussions. An Executive Committee facilitates the work of several subgroups, including an Inflation Probe Science Analysis Group (IPSAG), an X-ray group (XRSAG) , a gamma-ray,group (GRSAG), a gravitational wave group (GWSAG), and a cosmic-ray group (CRSAG). In addition to identifying opportunities and issues, these groups also help articulate technology needs. Membership in all the SAGs is completely open, with information and newsletter signups available on the PhysPAG pages at the PCOS program website. The PhysPAG reports to the Astrophysics Subcommittee of the NASA Advisory Council. A summary of PhysPAG activities will be given, along with time for questions and discussion.

  8. Comment on 'Nonlinear gyrokinetic theory with polarization drift' [Phys. Plasmas 17, 082304 (2010)

    SciTech Connect

    Leerink, S.; Parra, F. I.; Heikkinen, J. A.

    2010-12-15

    In this comment, we show that by using the discrete particle distribution function the changes of the phase-space volume of gyrocenter coordinates due to the fluctuating ExB velocity do not explicitly appear in the Poisson equation and the [Sosenko et al., Phys. Scr. 64, 264 (2001)] result is recovered. It is demonstrated that there is no contradiction between the work presented by Sosenko et al. and the work presented by [Wang et al., Phys. Plasmas 17, 082304 (2010)].

  9. Summary of PhysPAG Activities

    NASA Astrophysics Data System (ADS)

    Ritz, Steven M.

    2012-01-01

    The Physics of the Cosmos (PCOS) Program Analysis Group (PhysPAG) provides an important interface between the scientific community and NASA in matters related to PCOS objectives. An Executive Committee facilitates the work of several subgroups, including a Technology Science Analysis Group and an Inflation Probe Science Analysis Group. Work is also starting in areas of X-ray, gamma-ray, and gravitational wave astrophysics. The PAG reports to the Astrophysics Subcommittee of the NASA Advisory Council. A summary of PhysPAG activities will be given, along with time for questions and discussion.

  10. Analysis of bubbles and crashes in the TRY/USD, TRY/EUR, TRY/JPY and TRY/CHF exchange rate within the scope of econophysics

    NASA Astrophysics Data System (ADS)

    Deviren, Bayram; Kocakaplan, Yusuf; Keskin, Mustafa; Balcılar, Mehmet; Özdemir, Zeynel Abidin; Ersoy, Ersan

    2014-09-01

    In this study, we analyze the Turkish Lira/US Dollar (TRY/USD), Turkish Lira/Euro (TRY/EUR), Turkish Lira/Japanese Yen (TRY/JPY) and Turkish Lira/Swiss Franc (TRY/CHF) exchange rates in the global financial crisis period to detect the bubbles and crashes in the TRY by using a mathematical methodology developed by Watanabe et al. (2007). The methodology defines the bubbles and crashes in financial market price fluctuations by considering an exponential fitting of the associated data. This methodology is applied to detect the bubbles and crashes in the TRY/USD, TRY/EUR, TRY/JPY and TRY/CHF exchange rates from January, 1, 2005 to December, 20, 2013. In this mathematical methodology, the whole period of bubbles and crashes can be determined purely from past data, and the start of bubbles and crashes can be identified even before its bursts. In this way, the periods of bubbles and crashes in the TRY/USD, TRY/EUR, TRY/JPY and TRY/CHF are determined, and the beginning and end points of these periods are detected. The results show that the crashes in the TRY/CHF exchange rate are commonly finished earlier than in the other exchange rates; hence it is probable that the crashes in the other exchange rates would be finished soon when the crashes in the TRY/CHF exchange rate ended. We also find that the periods of crashes in the TRY/EUR exchange rate take longer time than in the other exchange rates. This information can be used in risk management and/or speculative gain. The crashes' periods in the TRY/EUR and TRY/USD exchange rates are observed to be relatively longer than in the other exchange rates.

  11. Response to 'Comment on 'Undamped electrostatic plasma waves''[Phys. Plasmas 20, 034701 (2013)

    SciTech Connect

    Valentini, F.; Perrone, D.; Veltri, P.; Califano, F.; Pegoraro, F.; Morrison, P. J.; O'Neil, T. M.

    2013-03-15

    Numerical and experimental evidence is given for the occurrence of the plateau states and concomitant corner modes proposed in Valentini et al.[Phys. Plasmas 19, 092103 (2012)]. It is argued that these states provide a better description of reality for small amplitude off-dispersion disturbances than the conventional Bernstein-Greene-Kruskal or cnoidal states such as those proposed in Schamel [Phys. Plasmas 20, 034701 (2013)].

  12. Response to ``Comment on `Undamped electrostatic plasma waves''' [Phys. Plasmas 20, 034701 (2013)

    NASA Astrophysics Data System (ADS)

    Valentini, F.; Perrone, D.; Califano, F.; Pegoraro, F.; Veltri, P.; Morrison, P. J.; O'Neil, T. M.

    2013-03-01

    Numerical and experimental evidence is given for the occurrence of the plateau states and concomitant corner modes proposed in Valentini et al. [Phys. Plasmas 19, 092103 (2012)]. It is argued that these states provide a better description of reality for small amplitude off-dispersion disturbances than the conventional Bernstein-Greene-Kruskal or cnoidal states such as those proposed in Schamel [Phys. Plasmas 20, 034701 (2013)].

  13. Comment on C. W. Wong, Maxwell equations and the redundant gauge degree of freedom 2009 Eur. J. Phys. 30, 1401-1416

    SciTech Connect

    Jackson, John David

    2009-10-22

    In the paper cited in the title, the author makes the claim that in classical electromagnetic theory the longitudinal electric field is instantaneous, corresponding to action at a distance, contrary to popular and correct belief. We point out that the determination of the speed of propagation of electromagnetic fields requires specification of the initial condition of the sources or equivalent. The Coulomb field of a stationary point charge proves nothing. We describe in detail a simple example to illustrate the universal onset of the static 'instantaneous' regime throughout a region of space that expands with the speed of light.

  14. Comment on 'Turbulent equipartition theory of toroidal momentum pinch' [Phys. Plasmas 15, 055902 (2008)

    SciTech Connect

    Peeters, A. G.; Angioni, C.; Strintzi, D.

    2009-03-15

    The comment addresses questions raised on the derivation of the momentum pinch velocity due to the Coriolis drift effect [A. G. Peeters et al., Phys. Rev. Lett. 98, 265003 (2007)]. These concern the definition of the gradient, and the scaling with the density gradient length. It will be shown that the turbulent equipartition mechanism is included within the derivation using the Coriolis drift, with the density gradient scaling being the consequence of drift terms not considered in [T. S. Hahm et al., Phys. Plasmas 15, 055902 (2008)]. Finally the accuracy of the analytic models is assessed through a comparison with the full gyrokinetic solution.

  15. Comment on "Effects of damping solitary wave in a viscosity bounded plasma" [Phys. Plasmas 21, 022118 (2014)

    NASA Astrophysics Data System (ADS)

    Ghosh, Uday Narayan; Chatterjee, Prasanta; Roychoudhury, Rajkumar

    2015-07-01

    Recently Gun Li et al. discussed "Effects of damping solitary wave in a viscosity bounded plasma" [Phys. Plasmas 21, 022118 (2014)]. The paper contains some serious errors which have been pointed out in this Comment.

  16. Comment on “Effects of damping solitary wave in a viscosity bounded plasma” [Phys. Plasmas 21, 022118 (2014)

    SciTech Connect

    Ghosh, Uday Narayan Chatterjee, Prasanta; Roychoudhury, Rajkumar

    2015-07-15

    Recently Gun Li et al. discussed “Effects of damping solitary wave in a viscosity bounded plasma” [Phys. Plasmas 21, 022118 (2014)]. The paper contains some serious errors which have been pointed out in this Comment.

  17. 78 FR 48765 - Bureau of European and Eurasian Affairs (EUR) Request for Proposals for the Fundraising...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Bureau of European and Eurasian Affairs (EUR) Request for Proposals for the Fundraising, Construction, Development, Organization, Management, Disassembly and Removal of a USA Pavilion/Exhibition at Universal Expo Milan Italy 2015, Hereafter Referred to...

  18. Back Cover: Eur. J. Immunol. 9'16.

    PubMed

    2016-09-01

    Our cover picture features an H&E staining of liver sections from mice with a mutation in the SH2 domain of the signal transducing adaptor protein slp-76. The application of concanavalin A (Con A) induces milder hepatitis in these mice than in wild-type B6 mice due to a decreased activation of invariant natural killer T (iNKT) cells. The image relates to the article by Danzer et al. (pp. 2121-2136) in which the authors describe a pivotal role of slp-76 in activation and tissue distribution of iNKT cells. PMID:27600676

  19. Inside Cover: Eur. J. Immunol. 6'16.

    PubMed

    2016-06-01

    Our inside cover features immunofluorescence staining of human tonsil sections with anti-CD4 (green) and anti-Bob1 (red) antibodies. Many plastic B cells expressing Bob1 are accumulated to form germinal centers surrounded by mantle zones. T follicular helper (Tfh) cells in and around the germinal centers are detected as cells expressing both CD4 and Bob1. The image is taken from article by Yamashita et al. (pp. 1361-1370), in which the authors show that Tfh cells highly express the transcription coactivator Bob1 and harbor a Bob1-related mechanism to restrict numerical frequency against stimuli of the T-cell receptor. PMID:27280484

  20. Back Cover: Eur. J. Immunol. 7'16.

    PubMed

    2016-07-01

    Our back cover features Luxol Fast Blue and H&E stainings of lumbar spinal cord from galectin-1 deficient (Lgals1(-/-) ) mice. Mice were immunized to induce experimental autoimmune encephalomyelitis (EAE) and treated with intravenous autoantigen. Demyelination and inflammation are apparent in the white matter of Lgals1(-/-) mice but is not present in C57BL/6 EAE mice treated with intravenous autoantigen. The image is taken from Mari et al. (pp. 1783-1796), where the authors present for the first time a role for galectin-1 in the induction of intravenous tolerance, providing new insights into the role of galectin-1 in a model of CNS autoimmune inflammation. PMID:27401873

  1. Erratum to “Comment on “Geometry effect on the magnetic ordering of geometrically frustrated rectangular and triangular magnets” [Phys. Lett. A 375 (13) (2011) 1548]” [Phys. Lett. A 375 (27) (2011) 2680-2681

    NASA Astrophysics Data System (ADS)

    Nascimento, F. S.; Mól, L. A. S.; Pereira, A. R.; Moura-Melo, W. A.

    2012-10-01

    In a recent comment [Phys. Lett. A 375 (2011) 2680] some of us argued that a misleading evaluation of dipolar interactions in spin ice systems studied by Li et al. [Phys. Lett. A 375 (2011) 1548], does not lead to the ground-state transitions that they observed. However, a bug found in our computational code showed that there is indeed the predicted transitions even for a proper evaluation of dipolar interactions.

  2. Back Cover: Eur. J. Immunol. 8'16.

    PubMed

    2016-08-01

    The cover shows a light sheet fluorescence microcopy image of a murine heart from diphtheria toxin treated CD11c-DTR mouse affected by fulminant myocarditis. The massive leukocyte infiltration was visualized by intravenous injection of fluorescent anti-CD45 antibodies. The autofluorescence channel reveals massive organ dilatation (grey). The leukocytic infiltrate is depicted in a heat map overlay from low (blue) to very high (bright yellow) and mainly affects the zone of the stimulus transduction system and the valves. The image is taken from Männ et al. (pp. 2028-2042) where the authors demonstrate, that a frequently used animal model for selective depletion of CD11c-expressing cells with diphtheria toxin suffers from a massive and 100% lethal phenotype of heart inflammation, which occurs within a few days after application of the toxin. This finding has important implications for previous and future studies using this animal model but may also provide a novel system to study fulminant myocarditis. PMID:27518704

  3. The new PhysTEC program at Boston University

    NASA Astrophysics Data System (ADS)

    Jenkins, Juliet; Duffy, Andrew

    2011-11-01

    The Boston University Physics Department was recently awarded a three-year grant from the Physics Teacher Education Coalition (PhysTEC). PhysTEC's main aims are to improve the education of future physics teachers, and to increase the number of qualified physics teachers in the school system. Although there have been over 20 PhysTEC-funded sites across the country, BU is the first PhysTEC site in New England. Our goals with this poster are to raise awareness about PhysTEC, and to talk about what we are doing and what we plan to do at BU with our PhysTEC funding. A key part of the PhysTEC program is the teacher-in-residence (TIR), an experienced physics teacher who comes to campus for a year to promote physics teaching as a profession and to lend their experience to education-related efforts. Our first TIR is Juliet Jenkins. The poster will discuss Ms. Jenkins' role in the Department of Physics and in the School of Education as we move forward with new efforts to promote teaching, including a Learning Assistant program, a pilot studio section of one of our introductory physics courses, and a new education course that allows undergraduate students to observe teachers in the classroom.

  4. MAC-bridging for multi-PHYs communication in BAN.

    PubMed

    Ullah, Sana; Khan, Pervez; Ullah, Niamat; Kwak, Kyung Sup

    2010-01-01

    Body Area Network (BAN) is a collection of low-power, miniaturised, and intelligent sensor nodes that are used for unobtrusive and ambulatory health monitoring of a patient without any additional constraints. These nodes operate on different frequency bands or Multiple Physical Layers (Multi-PHYs). Additionally, some BAN applications demand a logical connection between different nodes working on different Multi-PHYs. In this paper, the idea of controlling Multi-PHYs using one MAC protocol is introduced. Unlike existing procedures where different nodes working on different channels are connected at the link layer bridging/switching, the proposed procedure called bridging logically connects them at the MAC layer. In other words, the bridge is used to relay or filter packets between different PHYs in the same BAN. Numerical approximations are presented to analyze the stochastic behaviour of the bridges, all of them having Multi-PHYs interfaces. The MICS and the ISM bands are regarded as PHY1 and PHY2, respectively. The performance results are presented for PHY2 (given that data is already received from PHY1) in terms of probability of successful transmission, number of failed requests, power consumption, and delay. Simulations are conducted to validate the analytical results. It can be seen that the deployment of multiple bridges along with the corresponding nodes allows Multi-PHYs communication with high transmission probability, low power consumption, and tolerable delay. PMID:22163447

  5. ANN modeling for flood prediction in the upstream Eure's catchment (France)

    NASA Astrophysics Data System (ADS)

    Kharroubi, Ouissem; masson, Eric; Blanpain, Olivier; Lallahem, Sami

    2013-04-01

    Rainfall-Runoff relationship at basin scale is strongly depending on the catchment complexity including multi-scale interactions. In extreme events cases (i.e. floods and droughts) this relationship is even more complex and differs from average hydrological conditions making extreme runoff prediction very difficult to achieve. However, flood warning, flood prevention and flood mitigation rely on the possibility to predict both flood peak runoff and lag time. This point is crucial for decision making and flood warning to prevent populations and economical stakes to be damaged by extreme hydrological events. Since 2003 in France, a dedicated state service is in charge of producing flood warning from national level (i.e. SCHAPI) to regional level (i.e. SPC). This flood warning service is combining national weather forecast agency (i.e. Meteo France) together with a fully automated realtime hydrological network (i.e. Rainfall-Runoff) in order to produce a flood warning national map online and provide a set of hydro-meteorological data to the SPC in charge of flood prediction from regional to local scale. The SPC is in fact the flood service delivering hydrological prediction at operational level for decision making about flood alert for municipalities and first help services. Our research in collaboration with the SPC SACN (i.e. "Seine Aval et fleuves Côtiers Normands") is focused on the implementation of an Artificial Neural Network model (ANN) for flood prediction in deferent key points of the Eure's catchment and main subcatchment. Our contribution will focus on the ANN model developed for Saint-Luperce gauging station in the upstream part of the Eure's catchment. Prediction of extreme runoff at Saint-Luperce station is of high importance for flood warning in the Eure's catchment because it gives a good indicator on the extreme status and the downstream propagation of a potential flood event. Despite a good runoff monitoring since 27 years Saint Luperce flood

  6. Erratum: “Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Theory” [Phys. Plasmas 20, 092104 (2013)

    SciTech Connect

    Andreussi, T.; Morrison, P. J.; Pegoraro, F.

    2015-03-15

    An algebraic mistake in the rendering of the Energy Casimir stability condition for a symmetric magnetohydrodynamics plasma configuration with flows made in the article Andreussi et al. “Hamiltonian magnetohydrodynamics: Lagrangian, Eulerian, and dynamically accessible stability—Theory,” Phys. Plasmas 20, 092104 (2013) is corrected.

  7. Comment on "Replica-exchange-with-tunneling for fast exploration of protein landscapes" [J. Chem. Phys. 143, 224102 (2015)

    NASA Astrophysics Data System (ADS)

    Sakuraba, Shun

    2016-08-01

    In "Replica-exchange-with-tunneling for fast exploration of protein landscapes" [F. Yaşar et al., J. Chem. Phys. 143, 224102 (2015)], a novel sampling algorithm called "Replica Exchange with Tunneling" was proposed. However, due to its violation of the detailed balance, the algorithm fails to sample from the correct canonical ensemble.

  8. Response to 'Comment on 'Nonlinear properties of small amplitude dust ion acoustic solitary waves'' [Phys. Plasmas 15, 104703 (2008)

    SciTech Connect

    Gupta, M. R.; Sarkar, S.; Khan, Manoranjan; Ghosh, Samiran

    2008-10-15

    The objections are not justified. It should have been noted that ion charge number z{sub i}=1 throughout the referred paper [Ghosh et al., Phys. Plasmas 7, 3594 (2000)]. There is no inconsistency in the formulation of the referred paper as explained in the text.

  9. Comment on ``The application of the thermodynamic perturbation theory to study the hydrophobic hydration'' [J. Chem. Phys. 139, 024101 (2013)

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2013-09-01

    It is shown that the behaviour of the hydration thermodynamic functions obtained in the 3D Mercedes-Benz model of water by Mohoric et al. [J. Chem. Phys. 139, 024101 (2013)] is not qualitatively correct with respect to experimental data for a solute whose diameter is 1.5-fold larger than that of a water molecule. It is also pointed out that the failure is due to the fact that the used 3D Mercedes-Benz model of water [A. Bizjak, T. Urbic, V. Vlachy, and K. A. Dill, J. Chem. Phys. 131, 194504 (2009)] does not reproduce in a quantitatively correct manner the peculiar temperature dependence of water density.

  10. Comment on ``Equation of state of aluminum nitride and its shock response'' [J. Appl. Phys. 76, 4077 (1994)

    NASA Astrophysics Data System (ADS)

    Rosenberg, Z.; Brar, N. S.

    1995-11-01

    A recent article by Dandekar, Abbate, and Frankel [J. Appl. Phys. 76, 4077 (1994)] reviews existing data on high-pressure properties of aluminum nitride (AlN) in an effort to build an equation of state for this material. A rather large portion of that article is devoted to the shear strength of AlN and, in particular, to our data of 1991 with longitudinal and lateral stress gauges [Z. Rosenberg, N. S. Brar, and S. J. Bless, J. Appl. Phys. 70, 167 (1991)]. Since our highest data point has an error of 1 GPa, much of the discussion and conclusions of Dandekar and co-workers are not relevant once this error in data reduction is corrected. We also discuss the relevance of our shear strength data for various issues, such as the phase transformation of AlN at 20 GPa and the general shape of Hugoniot curves for brittle solids.

  11. Comment on "Surface electromagnetic wave equations in a warm magnetized quantum plasma" [Phys. Plasmas 21, 072114 (2014)

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2016-07-01

    In a recent article [C. Li et al., Phys. Plasmas 21, 072114 (2014)], Li et al. studied the propagation of surface waves on a magnetized quantum plasma half-space in the Voigt configuration (in this case, the magnetic field is parallel to the surface but is perpendicular to the direction of propagation). Here, we present a fresh look at the problem and obtain a new form of dispersion relation of surface waves of the system. We find that our new dispersion relation does not agree with the result obtained by Li et al.

  12. Comment on ``Undamped electrostatic plasma waves'' [Phys. Plasmas 19, 092103 (2012)

    NASA Astrophysics Data System (ADS)

    Schamel, Hans

    2013-03-01

    The relevance of linear "corner modes" for the description of coherent electrostatic structures, as proposed by Valentini et al. [Phys. Plasmas 19, 092103 (2012)], is questioned. Coherency in their on-dispersion simulation is instead found to be caused by particle trapping in agreement with Schamel's nonlinear wave model [Phys. Plasmas 19, 020501 (2012)]. The revealed small amplitude structures are hence of cnoidal electron hole type exhibiting vortices in phase space. They are ruled by trapping nonlinearity rather than by linearity or quasi-linear effects, as commonly assumed. Arguments are presented, which give preference to these cnoidal hole modes over Bernstein-Greene-Kruskal modes. To fully account for a realistic theoretical scenario, however, at least four ingredients are mandatory. Several corrections of the conventional body of thought about the proper kinetic wave description are proposed. They may prove useful for the general acceptance of this "new" nonlinear wave concept concerning structure formation, updating several prevailing concepts such as the general validity of a linear wave Ansatz for small amplitudes, as assumed in their paper. It is conjectured that this nonlinear trapping model can be generalized to the vortex structures of similar type found in the more general setting of driven turbulence of magnetized plasmas. They appear as eddies in both, the phase and the position spaces, embedded intermittently on the Debye length scale.

  13. Components of a standardised olive leaf dry extract (Ph. Eur.) promote hypothiocyanite production by lactoperoxidase.

    PubMed

    Flemmig, Jörg; Rusch, Dorothea; Czerwińska, Monika Ewa; Rauwald, Hans-Wilhelm; Arnhold, Jürgen

    2014-05-01

    We investigated in vitro the ability of a standardised olive leaf dry extract (Ph. Eur.) (OLE) as well as of its single components to circumvent the hydrogen peroxide-induced inhibition of the hypothiocyanite-producing activity of lactoperoxidase (LPO). The rate of hypothiocyanite (⁻OSCN) formation by LPO was quantified by spectrophotometric detection of the oxidation of 5-thio-2-nitrobenzoic acid (TNB). By using excess hydrogen peroxide, we forced the accumulation of inactive enzymatic intermediates which are unable to promote the two-electronic oxidation of thiocyanate. Both OLE and certain extract components showed a strong LPO-reactivating effect. Thereby an o-hydroxyphenolic moiety emerged to be essential for a good reactivity with the inactive LPO redox states. This basic moiety is found in the main OLE components oleuropein, oleacein, hydroxytyrosol, caffeic acid as well as in different other constituents including the OLE flavone luteolin. As LPO is a key player in the humoral immune response, these results propose a new mode of action regarding the well-known bacteriostatic and anti-inflammatory properties of the leaf extract of Olea europaea L. PMID:24657078

  14. Comment on 'Effects of magnetic field gradient on ion beam current in cylindrical Hall ion source' [J. Appl. Phys. 102, 123305 (2007)

    SciTech Connect

    Raitses, Y.; Smirnov, A.; Fisch, N. J.

    2008-09-15

    It is argued that the key difference in the cylindrical Hall thruster (CHT) as compared to the end-Hall ion source cannot be exclusively attributed to the magnetic field topology [Tang et al., J. Appl. Phys. 102, 123305 (2007)]. With a similar mirror-type topology, the CHT configuration provides the electric field with nearly equipotential magnetic field surfaces and a better suppression of the electron cross-field transport, as compared to both the end-Hall ion source and the cylindrical Hall ion source of [Tang et al., J. Appl. Phys. 102, 123305 (2007)].

  15. Comment on "Frequency-domain stimulated and spontaneous light emission signals at molecular junctions" [J. Chem. Phys. 141, 074107 (2014)

    NASA Astrophysics Data System (ADS)

    Galperin, Michael; Ratner, Mark A.; Nitzan, Abraham

    2015-04-01

    We discuss the derivation of the optical response in molecular junctions presented by U. Harbola et al. [J. Chem. Phys. 141, 074107 (2014)], which questions some terms in the theory of Raman scattering in molecular junctions developed in our earlier publications. We show that the terms considered in our theory represent the correct contribution to calculated Raman scattering and are in fact identical to those considered by Harbola et al. We also indicate drawbacks of the presented approach in treating the quantum transport part of the problem.

  16. PREFACE: Prospects in Neutrino Physics 2013 - NuPhys2013

    NASA Astrophysics Data System (ADS)

    2015-04-01

    The first "Prospects in Neutrino Physics 2013 - NuPhys2013" conference was held at the Institute of Physics, IoP, London, 19-20 December 2013 and was attended by about 130 delegates from institutions worldwide. Lunch and coffee breaks allowed discussions among delegates and speakers to take place in an informal setting. This conference is unique in discussing the worldwide strategy to address unresolved issues in neutrino physics, and shape the future directions of particle physics. We discussed the current status and focussed especially on the prospects of future experiments, their performance and physics reach. It is particularly timely due to the recent measurements in neutrino physics and planned worldwide experiments. The following topics were addressed: • Theory and Phenomenology Perspectives • Future Long and Short Baseline Neutrino Oscillation Experiments • Reactor neutrino and flux • Neutrinoless double beta decays • Solar, atmospheric, supernova neutrinos • Neutrino cosmology in which both the phenomenological and experimental aspects were equally addressed. World-leading experts in the different neutrino areas were invited to give review talks. To encourage and facilitate the participation of early-career researchers and PhD students, a poster session formed a key aspect of this meeting. The conference was organized by Francesca Di Lodovico and Silvia Pascoli. It was sponsored by the IoP through their Topic Research Meeting Grant, and also supported by Durham IPPP, ERC-207282, FP7 invisibles project, Queen Mary University of London.

  17. Comment on ``Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends'' [J. Chem. Phys. 138, 054903 (2013)

    NASA Astrophysics Data System (ADS)

    Colmenero, J.

    2013-05-01

    In a recent paper by Ngai and Capaccioli ["Unified explanation of the anomalous dynamic properties of highly asymmetric polymer blends," J. Chem. Phys. 138, 054903 (2013), 10.1063/1.4789585] the authors claimed that the so-called coupling model (CM) provides a unified explanation of all dynamical anomalies that have been reported for dynamically asymmetric blends over last ten years. Approximately half of the paper is devoted to chain-dynamic properties involving un-entangled polymers. According to the authors, the application of the CM to these results is based on the existence of a crossover at a time tc ≈ 1-2 ns of the magnitudes describing chain-dynamics. Ngai and Capaccioli claimed that the existence of such a crossover is supported by the neutron scattering and MD-simulation results, corresponding to the blend poly(methyl methacrylate)/poly(ethylene oxide), by Niedzwiedz et al. [Phys. Rev. Lett. 98, 168301 (2007), 10.1103/PhysRevLett.98.168301] and Brodeck et al. [Macromolecules 43, 3036 (2010), 10.1021/ma902820a], respectively. Being one of the authors of these two papers, I will demonstrate here that there is no evidence supporting such a crossover in the data reported in these papers.

  18. Comment on “Maxwell's equations and electromagnetic Lagrangian density in fractional form” [J. Math. Phys. 53, 033505 (2012)

    SciTech Connect

    Rabei, Eqab M.; Al-Jamel, A.; Widyan, H.; Baleanu, D.

    2014-03-15

    In a recent paper, Jaradat et al. [J. Math. Phys. 53, 033505 (2012)] have presented the fractional form of the electromagnetic Lagrangian density within the Riemann-Liouville fractional derivative. They claimed that the Agrawal procedure [O. P. Agrawal, J. Math. Anal. Appl. 272, 368 (2002)] is used to obtain Maxwell's equations in the fractional form, and the Hamilton's equations of motion together with the conserved quantities obtained from fractional Noether's theorem are reported. In this comment, we draw the attention that there are some serious steps of the procedure used in their work are not applicable even though their final results are correct. Their work should have been done based on a formulation as reported by Baleanu and Muslih [Phys. Scr. 72, 119 (2005)].

  19. Preface: phys. stat. sol. (b) 241/9

    NASA Astrophysics Data System (ADS)

    Morawetz, Klaus

    2004-07-01

    Modelling and Simulation in Molecular Systems, Mesoscopic Structures, and Material Science was the title of a workshop held at the University of Technology in Chemnitz from 21 to 23 April 2004. This workshop coincided with the 50th birthday of Michael Schreiber. Therefore, the idea to publish a special issue is supported by two good reasons. First, a topical collection is appropriate for giving an overview about a field and to initiate further studies. This is one intention of the present issue. Second, the birthday is a suitable occasion for reflecting on the status of the different fields where Michael Schreiber has been active himself. Motivated by the characteristic name of the workshop (MS4), which expresses the broad range of his activities, the contributions are grouped into three main chapters: Disorder and Interaction, Phase Transitions and Criticality, and Transport Properties.The first part starts with the currently intensively discussed topic of composite Fermions in the paper by B. Kramer et al. This method of rewriting correlations as new quasiparticles has amongst other things the merit of explaining such exciting phenomena as the fractional quantum Hall effect. The methodological questions of Ward identities, causality, and conservation laws are the focus of the systematic investiga-tion in the second article by V. Janis et al. which concentrates on the problem of disorder and configura-tional averaging. The interplay between disorder and correlation is treated in the third contribution by C. Schuster et al., where different theoretical methods are tested on the problem of Friedel oscillations within the one-dimensional Heisenberg and Hubbard model. In the next contribution, M. Berciu et al. focus on localization as one consequence of disorder. The localized and extended electronic states are treated, together with the magnetic degrees of freedom, like spin waves. One of the astonishing consequence of localiza-tion is the observation of resonant

  20. Comment on "In situ imaging of ultra-fast loss of nanostructure in nanoparticle aggregates" [J. Appl. Phys. 115, 084903 (2014)

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; Hwang, Yong Seok

    2016-02-01

    One of the conclusions of a recent article by Egan et al. [J. Appl. Phys. 115, 084903 (2014)] was that since the melt-dispersion mechanism (MDM) of the reaction of aluminum nanoparticles was not observed in their experiments, this mechanism is very unlikely. Our main point here is to demonstrate that, in fact, these experiments do not disprove the MDM.

  1. Comment on ''Chaotic electron trajectories in an electromagnetic wiggler free-electron laser with ion-channel guiding'' [Phys. Plasmas 17, 093103 (2010)

    SciTech Connect

    Nasr, N.; Hasanbeigi, A.

    2011-05-15

    The chaotic electron dynamics in a free-electron laser with electromagnetic-wave wiggler and ion-channel has been recently reported by A. Taghavi et al.[Phys. Plasmas 17, 093103 (2010)]. We comment on the authors use of a set of initial condition that is not correct based on the dispersion relation and steady-state orbits.

  2. Response to ``Comment on `Slow Debye-type peak observed in the dielectric response of polyalcohols' '' [J. Chem. Phys. 134, 037101 (2011)

    NASA Astrophysics Data System (ADS)

    Bergman, R.; Jansson, H.; Swenson, J.

    2011-01-01

    In our recent article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)] we investigated some polyalcohols, i.e., glycerol, xylitol, and sorbitol by dielectric spectroscopy. In the study, a low-frequency peak of Debye character that normally is hidden by the large low-frequency dispersion due to conductivity was revealed by analyzing the real part of the permittivity and by using a thin Teflon film to suppress the low-frequency dispersion. We agree with the comment by Paluch et al. [J. Chem. Phys. 134, 037101 (2011)] that the Teflon film setup will indeed create a peak due to the dc conductivity. However, due to the fact that the location of the peak was almost identical in measurement with and without Teflon, we unfortunately mainly showed the data measured with Teflon, despite that it could also be observed in the real part of the permittivity without using the Teflon setup, as shown in our original article [R. Bergman et al., J. Chem. Phys. 132, 044504 (2010)]. Here, we show that the low-frequency peak of Debye character can also be observed by subtracting the dc conductivity. Furthermore, we show that the modulus representation used in Paluch et al. [J. Chem. Phys. 134, 037101 (2011).] is also not suitable for detecting processes hidden by the conductivity.

  3. Alternative to Ph. Eur. pour-plate method for detection of microbial contamination in non-sterile pharmaceutical preparations.

    PubMed

    Palicz, A; Paul, A; Hofmann, A; Denzel, K

    2016-01-01

    The current European Pharmacopoeia (Ph. Eur.) texts for Interferon (IFN)-alfa-2 include a nonspecific photometric protein assay using albumin as calibrator and a highly variable cell-based assay for the potency determination of the protective effects. A request was expressed by the Official Medicines Control Laboratories (OMCLs) for improved methods for the batch control of recombinant interferon alfa-2 bulk and market surveillance testing of finished products, including those formulated with Human Serum Albumin (HSA). A HPLC method was developed at the Medical Products Agency (MPA, Sweden) for the testing of IFN-alfa-2 products. An initial collaborative study run under the Biological Standardisation Programme (BSP; study code BSP039) revealed the need for minor changes to improve linearity of the calibration curves, assay reproducibility and robustness. The goal of the collaborative study, coded BSP071, was to transfer and further validate this improved HPLC method. Ten laboratories participated in the study. Four marketed IFN-alfa-2 preparations (one containing HSA) together with the Ph. Eur. Chemical Reference Substance (CRS) for IFN-alfa-2a and IFN-alfa-2b, and in-house reference standards from two manufacturers were used for the quantitative assay. The modified method was successfully transferred to all laboratories despite local variation in equipment. The resolution between the main and the oxidised forms of IFN-alfa-2 was improved compared to the results from the BSP039 study. The improved method even allowed partial resolution of an extra peak after the principal peak. Symmetry of the main IFN peak was acceptable for all samples in all laboratories. Calibration curves established with the Ph. Eur. IFN-alfa-2a and IFN-alfa-2b CRSs showed excellent linearity with intercepts close to the origin and coefficients of determination greater than 0.9995. Assay repeatability, intermediate precision and reproducibility varied with the tested sample within acceptable

  4. Physics of the Cosmos Program Analysis Group (PhysPAG) Report

    NASA Astrophysics Data System (ADS)

    Nousek, John A.

    2015-01-01

    The Physics of the Cosmos Program Analysis Group (PhysPAG) serves as a forum for soliciting and coordinating input and analysis from the scientific community in support of the PCOS program objectives. I will outline the activities of the PhysPAG over the past year, since the last meeting during the AAS meeting in National Harbor, and mention the activities of the PhysPAG related Scientific Interest Groups.

  5. Response to "Comment on `Diffusion of n-type dopants in germanium' " [Appl. Phys. Rev. 2, 036101 (2015)

    NASA Astrophysics Data System (ADS)

    Bracht, H.; Südkamp, T.; Radek, M.; Chroneos, A.

    2015-09-01

    In this reply to the comment of Cowern et al., we demonstrate on the basis of full numerical simulations of radiation enhanced dopant diffusion via the kick-out mechanism that the g/λ analysis fails to consistently describe boron (B) diffusion in germanium (Ge) under irradiation. Cowern et al. missed to perform a consistency check with results for the diffusivity DI of Ge interstitials (I) determined from Ge self-diffusion under irradiation. Data deduced for DI from the exponential B profile reported by Cowern et al. deviate several orders of magnitude from the self-diffusion study. This clearly disproves the validity of the kick-out mechanism to control radiation enhanced B diffusion in Ge. Exponential B profiles like those established in Ge under irradiation are also reported for silicon by Venezia et al. [Phys. Rev. B 69, 125215 (2004)]. The characteristic shape is not described by the kick-out mechanism but rather explained qualitatively by the complex formation and dissolution of defect clusters. Modeling of B diffusion in Ge under irradiation performed by Schneider et al. [Phys. Rev. B 87, 115202 (2013)] is fully consistent with self-diffusion under irradiation. This constraint led us to conclude that the characteristic B profiles are additionally affected by the formation of immobile B clusters. Although a direct microscopic proof of B cluster formation is still lacking, the report of Venezia et al. on B clustering in Si during irradiation with similar exponential B profiles also supports our interpretation of B diffusion in Ge under irradiation.

  6. Comment on 'Dynamics of an electron driven by relativistically intense laser radiation' [Phys. Plasmas 15, 023104 (2008)

    SciTech Connect

    Tian Youwei; Bao Gang; Zheng Ying; Yang Jianping; Yu Wei; Wang Xin

    2010-06-15

    Galkin et al. [Phys. Plasmas 15, 023104 (2008)] presented the comparison of the electron dynamics in the cases of the linear and circular polarizations of the optical fields. They assume that the longitudinal component of the laser field can be neglected in the case of longitudinal displacement less than the Rayleigh range. In this comment, we point out that the longitudinal component must be considered for the minimum spot size less than 10 times wavelength for linearly polarized laser pulse and for the minimum spot size less than 15 times wavelength for circularly polarized laser pulse.

  7. Comment on "Size-efficient metamaterial absorber at low frequencies: Design, fabrication, and characterization" [J. Appl. Phys. 117, 243105 (2015)

    NASA Astrophysics Data System (ADS)

    Liu, Lulu; Liu, Shaobin; Zhang, HaiFeng; Kong, Xiangkun; Yang, Hua; Ding, Guowen; Xu, Ce; Wang, Lingling; Shi, Wei

    2016-06-01

    In a recent article, Khuyen et al. [J. Appl. Phys. 117, 243105 (2015)] proposed a metamaterial perfect absorber (MPA) with a self-asymmetric structure and claimed that it could produce dual-band "perfect absorption." In this report, we demonstrate that the self-asymmetric structure is not a true MPA. The cross-polarization reflection, which is induced by coupling between the induced magnetic field and the incident electric field, is ignored in calculation of absorptivity of that structure. The real absorption rate of this structure is below 60%, which indicates that the structure cannot be called a perfect absorber.

  8. Preface: phys. stat. sol. (a) 202/12

    NASA Astrophysics Data System (ADS)

    Neumann, Wolfgang; Stutzmann, Martin; Hildebrandt, Stefan

    2005-09-01

    The present special issue contains a collection of Original Papers dedicated to Professor Johannes Heydenreich on the occasion of his 75th birthday.Johannes Heydenreich, born on 20 June 1930 in Plauen/Vogtland near Dresden, studied physics at the Pädagogische Hochschule Potsdam, where he obtained his first academic degree Dipl. Phys. in 1958. He received his doctoral degree at the Martin Luther University in Halle in 1961 and the Habilitation degree in 1969. Already during his studies in Potsdam, he showed an interest in electron microscopy due to the influence of his teacher and supervisor Prof. Picht, one of the pioneers in electron optics. His interests were strengthened when Johannes Heydenreich did the experimental work for his Diploma degree at the Institute for Experimental Physics of the University of Halle, where he met Prof. Heinz Bethge for the first time. This was the beginning of a fruitful and longstanding collaboration. In 1962 Johannes Heydenreich joined the team of the later Institute for Solid State Physics and Electron Microscopy of the Academy of Sciences of the GDR, in Halle, for which the basis was laid by Prof. Bethge in 1960.Heydenreich has been working as Assistant Director for many years and played a decisive role in introducing and organising the various techniques of electron microscopy in the institute.The research activities of Prof. Heydenreich covered a broad spectrum over the years. At the beginning of his career he made significant contributions in the field of electron mirror microscopy. After that, his main interests were focused on transmission electron microscopy, ranging from diffraction contrast analysis of crystal defects to high-resolution electron microscopy and image processing. His favourite field was studies of defect-induced phenomena in advanced materials. The so-called Bethge-Heydenreich, the book Electron Microscopy in Solid State Physics, published at first in a German edition in 1982 and later in a revised

  9. Preface: phys. stat. sol. (a) 202/7

    NASA Astrophysics Data System (ADS)

    Pollak, Fred H.; Misiewicz, Jan; Sitarek, Piotr

    2005-05-01

    We have recently observed a growing interest in using the powerful technique of optical modulation spectroscopy. These applications are related mostly to the characterization of low dimensional semiconductor structures and devices based on them.The International Workshop on Modulation Spectroscopy of Semiconductor Structures (MS3) at the beginning of July 2004 gathered in Wrocaw (in the southwest part of Poland) almost 40 participants, half of them from abroad. The 8 invited and 16 contributed talks were presented by the leaders of research teams from the USA, Japan, Taiwan, Canada, Germany, France, the Netherlands, Sweden, Ireland, Russia, Lithuania and Poland. Part of the MS3 workshop was held at the Laboratory of Advanced Optical Spectroscopy, Institute of Physics, Wrocaw University of Technology, where discussions on technical matter of the modulation spectroscopy were carried out in a relaxing atmosphere over a cup of coffee.The topics of the MS3 workshop included: advantages of photoreflectance, electroreflectance, contactless electroreflectance, thermoreflectance, differential reflectance and wavelength-modulated surface photovoltage spectroscopy. The applications of the above methods to investigate transistor, diode and laser structures including VCSELs, low dimensional structures of both wings of the spectrum, i.e. wide band gap materials like GaN, AlGaN, ZnO and low band gap materials such as GaInN(Sb)As, InAs, InSb, and FeSi2 were demonstrated.It is our great pleasure to publish the most interesting of the MS3 workshop presentations in this issue of physica status solidi (a).The organizers acknowledge Wrocaw University of Technology, the Center of Exellence CEPHONA from the Institute of Electron Technology in Warsaw and the Polish Committee for Scientific Research for financial support of the workshop.

  10. Comment on "Diffusion of n-type dopants in germanium" [Appl. Phys. Rev. 1, 011301 (2014)

    NASA Astrophysics Data System (ADS)

    Cowern, N. E. B.; Simdyankin, S.; Goss, J. P.; Napolitani, E.; De Salvador, D.; Bruno, E.; Mirabella, S.; Ahn, C.; Bennett, N. S.

    2015-09-01

    The authors of the above paper call into question recent evidence on the properties of self-interstitials, I, in Ge [Cowern et al., Phys. Rev. Lett. 110, 155501 (2013)]. We show that this judgment stems from invalid model assumptions during analysis of data on B marker-layer diffusion during proton irradiation, and that a corrected analysis fully supports the reported evidence. As previously stated, I-mediated self-diffusion in Ge exhibits two distinct regimes of temperature, T: high-T, dominated by amorphous-like mono-interstitial clusters—i-morphs—with self-diffusion entropy ≈30 k, and low-T, where transport is dominated by simple self-interstitials. In a transitional range centered on 475 °C both mechanisms contribute. The experimental I migration energy of 1.84 ± 0.26 eV reported by the Münster group based on measurements of self-diffusion during irradiation at 550 °C < T < 680 °C further establishes our proposed i-morph mechanism.

  11. Preface: phys. stat. sol. (b) 242/9

    NASA Astrophysics Data System (ADS)

    Sánchez, Maria

    2005-07-01

    The XVII Latin American Symposium on Solid State Physics took place in the conference rooms of the Convent San Francisco de Asis, in the heart of the Old Havana. The sixteen previous editions were organized in eight different countries; the last two were in Colombia (Cartagena, 1999) and Venezuela (Merida, 2002). After eighteen years the meeting came back to Havana in 2004.The program topics included: Surfaces and interfaces analysis; Spintronics; Magnetism; Materials and energy; Ab-initio methods, simulations and modeling in solids; Nanophysics, nanomaterials and nanotechnology; New materials, properties and applications; Preparation of materials, thin films and characterization; High temperature superconductivity; Techniques of structural analysis in solids. The program included 6 plenary talks, 13 invited talks, 58 oral presentations (in eight sessions) and 200 poster contributions (in four poster sessions).The meeting attracted more than 200 participants from 14 countries. The physica status solidi Young Researcher Award sponsored by Wiley-VCH was conferred at the meeting. This prize was divided between two participants: Clara Calderón (Study of electrical transport properties of ZnO thin films used as front contact of solar cells) from Colombia and Aim?? Pelaiz Barranco (AC behavior in lanthanum modified PZT ferroelectric ceramics) from Cuba. Special Mentions went to Val??rie Halté (Femtosec-ond dynamics of transmission of gold arrays of sub-wavelength holes) from France, Erick Larramendi Cancio (Cd desorption induced by Zn exposure during atomic layer epitaxy of CdxZn1-xTe) and Julio Cesar Rimada Herrera (Quantum and conversion efficiency calculation of AlGaAs/GaAs multiple quantum well solar cells) from Cuba.Nanostructures and in general low dimensional physics related to different systems was a very hot topic during the meeting. Some talks and presentations were devoted to optoelectronic materials and devices. Characterization of solids by different

  12. Comment on ``Study of dielectric relaxations of anhydrous trehalose and maltose glasses'' [J. Chem. Phys. 134, 014508 (2011)

    NASA Astrophysics Data System (ADS)

    Kaminski, K.; Wlodarczyk, P.; Paluch, M.

    2011-10-01

    Very recently Kwon et al. [H.-J. Kwon, J.-A. Seo, H. K. Kim, and Y. H. Hwang, J. Chem. Phys. 134, 014508 (2011)] published an article on the study of dielectric relaxation in trehalose and maltose glasses. They carried out broadband dielectric measurements at very wide range of temperatures covering supercooled liquid as well as glassy state of both saccharides. It is worth to mention that authors have also applied a new method for obtaining anhydrous glasses of trehalose and maltose that enables avoiding their caramelization. Four relaxation processes were identified in dielectric spectra of both saccharides. The slower one was identified as structural relaxation process the next one, not observed by the others, was assigned as Johari-Goldstein (JG) β-relaxation, while the last two secondary modes were of the same nature as found by Kaminski et al. [K. Kaminski, E. Kaminska, P. Wlodarczyk, S. Pawlus, D. Kimla, A. Kasprzycka, M. Paluch, J. Ziolo, W. Szeja, and K. L. Ngai, J. Phys. Chem. B 112, 12816 (2008)]. In this comment we show that the authors mistakenly assigned the slowest relaxation process as structural mode of disaccharides. We have proven that this relaxation process is an effect of formation of thin layer of air or water between plate of capacitor and sample. The same effect can be observed if plates of capacitor are oxidized. Thus, we concluded that their slowest mode is connected to the dc conduction process while their β JG process is primary relaxation of trehalose and maltose.

  13. Preface: phys. stat. sol. (b) 242/1

    NASA Astrophysics Data System (ADS)

    Ginzburg, V. L.; Maksimov, E. G.

    2005-01-01

    structure. This point is discussed by J. Phillips in this issue.There are also many experimental indications in favor of the existence of a strong EPI in the HTSC cuprates. For example, the behavior of the electron relaxation, the peculiarities of the phonon spectra, the interaction of the Josephson current with phonons, and the electron mass renormalization. All these phenomena have been discussed in the recent Review Articles [3, 4]. Currently, additional evidence was provided which has thrown new light on the role played by the EPI in HTSC systems. These are the ARPES experiments conducted by the Stanford group, which have given an unambiguous proof of the electron mass renormalization due to the EPI. A Review Article of this group by T. Cuk et al. is also presented in this issue. We should also mention the contribution of L. Pintschovius who presented new interesting results on the electron-phonon coupling effects observed by means of inelastic neutron scattering.A comprehensive discussion of a major part of the electron-phonon coupling effects presented in the Review Articles [1, 3] has been based on the traditional approach of the Eliashberg type. Up to now, we consider this approach to be quite suitable for pursuing a number of goals, mainly for describing properties of the normal state. Nevertheless, we do not disclaim the importance of more detailed investigations of the EPI, which take into account the strong anisotropy, the interplay between electron-phonon and electron-electron interaction, and the non-adiabatic effects. Four Review Articles in this issue, by Schneider, by Rösch, Han, Gunnarsson and Crespi, by Kuli and Dolgov, and by Cappelluti and Pietronero are devoted to different aspects of these problems.To conclude, we would like to emphasize that the main problem related to the mechanism of superconductivity in the HTSC cuprates is the interplay between the strong EPI and the electron exchange and correlation. Unfortunately, previous work did not crack

  14. Comment on 'The diatomic dication CuZn{sup 2+} in the gas phase' [J. Chem. Phys. 135, 034306 (2011)

    SciTech Connect

    Fiser, Jiri; Diez, Reinaldo Pis; Franzreb, Klaus; Alonso, Julio A.

    2013-02-21

    In this Comment, the density functional theory (DFT) calculations carried out by Diez et al. [J. Chem. Phys. 135, 034306 (2011)] are revised within the framework of the coupled-cluster single double triple method. These more sophisticated calculations allow us to show that the {sup 2}{Sigma}{sup +} electronic ground state of CuZn{sup 2+}, characterized as the metastable ground state by DFT calculations, is a repulsive state instead. The {sup 2}{Delta} and {sup 2}{Pi} metastable states of CuZn{sup 2+}, on the other hand, should be responsible for the formation mechanism of the dication through the near-resonant electron transfer CuZn{sup +}+ Ar{sup +}{yields} CuZn{sup 2+}+ Ar reaction.

  15. Comment on “Two-dimensional positive column structure in a discharge tube with radius discontinuity” [Phys. Plasmas 21, 113503 (2014)

    SciTech Connect

    Demidova, M. V.; Kudryavtsev, A. A.; Kurlyandskaya, I. P.; Saifutdinov, A. I.; Stepanova, O. M.

    2015-09-15

    Zobnin et al. have published a paper [Phys. Plasmas, 21, 113503 (2014)] on a topic of discharge physics in the presence of a sharp change in cylindrical discharge geometry. In the comment it is pointed out that for untrapped electrons a full kinetic equation, which includes dependences on spatial coordinates and energies, has to be used for the electron velocity distribution function determination. It is also unclear what probe theories Zobnin et al. have used in their paper for the calculation of electron current to the discharge tube wall.

  16. Comment on “Frequency-domain stimulated and spontaneous light emission signals at molecular junctions” [J. Chem. Phys. 141, 074107 (2014)

    SciTech Connect

    Galperin, Michael; Ratner, Mark A.; Nitzan, Abraham

    2015-04-07

    We discuss the derivation of the optical response in molecular junctions presented by U. Harbola et al. [J. Chem. Phys. 141, 074107 (2014)], which questions some terms in the theory of Raman scattering in molecular junctions developed in our earlier publications. We show that the terms considered in our theory represent the correct contribution to calculated Raman scattering and are in fact identical to those considered by Harbola et al. We also indicate drawbacks of the presented approach in treating the quantum transport part of the problem.

  17. Comment on "Study of dielectric relaxations of anhydrous trehalose and maltose glasses" [J. Chem. Phys. 134, 014508 (2011)].

    PubMed

    Kaminski, K; Wlodarczyk, P; Paluch, M

    2011-10-28

    Very recently Kwon et al. [H.-J. Kwon, J.-A. Seo, H. K. Kim, and Y. H. Hwang, J. Chem. Phys. 134, 014508 (2011)] published an article on the study of dielectric relaxation in trehalose and maltose glasses. They carried out broadband dielectric measurements at very wide range of temperatures covering supercooled liquid as well as glassy state of both saccharides. It is worth to mention that authors have also applied a new method for obtaining anhydrous glasses of trehalose and maltose that enables avoiding their caramelization. Four relaxation processes were identified in dielectric spectra of both saccharides. The slower one was identified as structural relaxation process the next one, not observed by the others, was assigned as Johari-Goldstein (JG) β-relaxation, while the last two secondary modes were of the same nature as found by Kaminski et al. [K. Kaminski, E. Kaminska, P. Wlodarczyk, S. Pawlus, D. Kimla, A. Kasprzycka, M. Paluch, J. Ziolo, W. Szeja, and K. L. Ngai, J. Phys. Chem. B 112, 12816 (2008)]. In this comment we show that the authors mistakenly assigned the slowest relaxation process as structural mode of disaccharides. We have proven that this relaxation process is an effect of formation of thin layer of air or water between plate of capacitor and sample. The same effect can be observed if plates of capacitor are oxidized. Thus, we concluded that their slowest mode is connected to the dc conduction process while their β JG process is primary relaxation of trehalose and maltose. PMID:22047271

  18. e-Phys: a suite of intracellular neurophysiology programs integrating COM (component object model) technologies.

    PubMed

    Nguyen, Quoc-Thang; Miledi, Ricardo

    2003-09-30

    Current computer programs for intracellular recordings often lack advanced data management, are usually incompatible with other applications and are also difficult to adapt to new experiments. We have addressed these shortcomings in e-Phys, a suite of electrophysiology applications for intracellular recordings. The programs in e-Phys use Component Object Model (COM) technologies available in the Microsoft Windows operating system to provide enhanced data storage, increased interoperability between e-Phys and other COM-aware applications, and easy customization of data acquisition and analysis thanks to a script-based integrated programming environment. Data files are extensible, hierarchically organized and integrated in the Windows shell by using the Structured Storage technology. Data transfers to and from other programs are facilitated by implementing the ActiveX Automation standard and distributed COM (DCOM). ActiveX Scripting allows experimenters to write their own event-driven acquisition and analysis programs in the VBScript language from within e-Phys. Scripts can reuse components available from other programs on other machines to create distributed meta-applications. This paper describes the main features of e-Phys and how this package was used to determine the effect of the atypical antipsychotic drug clozapine on synaptic transmission at the neuromuscular junction. PMID:12948545

  19. Comments on ``The Euclidean gravitational action as black hole entropy, singularities, and space-time voids'' [J. Math. Phys. 49, 042501 (2008)

    NASA Astrophysics Data System (ADS)

    Mitra, Abhas

    2009-04-01

    We point out that the space-time void inferred by Castro [J. Math. Phys. 49, 042501 (2008)] results from his choice of a discontinuous radial gauge. Further since the integration constant α0=2M0 (G =c=1) occurring in the vacuum Hilbert/Schwarzschild solution of a neutral "point mass" is zero [Arnowitt et al., in Gravitation: An Introduction to Current Research, edited by L. Witten (Wiley, New York, 1962), Chap. 7, p. 227; also Phys. Rev. Lett. 4, 375 (1960). A. Mitra, Adv. Space Res. 38, 2917 (2006); Proceedings of the XIth Marcel-Grossmann Conference on General Relativity (World Scientific, Singapore, 2008), Vol. 3, p. 1968], Castro's gauge reduces to the well behaved and physical Hilbert gauge. Physically this means that true Hilbert/Schwarzschild black holes have unique gravitational mass M =0. Accordingly, the unphysical space-time void inferred by Castro is actually nonexistent.

  20. Role and goals of the EUR-OCEANS Consortium - Bringing marine scientists priorities and strategies to the European research planning agenda.

    NASA Astrophysics Data System (ADS)

    Cury, Philippe; Baisnée, Pierre-François

    2010-05-01

    The EUR-OCEANS Consortium is the follow-up structure of the homonym European Network of Excellence (NoE; 2005-2008, FP6 contract number 511106). It is a scientific network, benefiting from and relying upon the institutional commitment of the 27 research performing organisations forming its core (paying) membership. It aims at the long-term harmonization of European research efforts related to ocean ecosystems undergoing anthropogenic and natural forcing. More specifically, its objectives are to facilitate and promote: (1) top-level scientific research on the impacts of anthropogenic and natural forcing on ocean ecosystems, fostering collaborations across the European Research Area; (2) the optimal use of any shared technical infrastructures and scientific facilities; and (3) activities to spread excellence, such as the training of scientific personnel and students, or knowledge dissemination towards the general public and socio-economic users. A particular focus is put during the first scientific coordination mandate on the building of scenarios for marine ecosystems under anthropogenic and natural forcing in the XXI Century, and on the improvement of the science-policy interface. Through calls for projects and networking activities, the Consortium seeks to favour the emergence of coordinated projects on key hot topics on one hand, and the crystallisation of scientific priorities and strategies that could serve as input to ERA-NETs, ESFRI, Joint Programming Initiatives and European Research Planning actors in general. While being an active standalone structure, the Consortium is also engaged in the Euromarine FP7 project (submitted) aiming at the definition of a common coordinating or integrating structure for the three follow-up entities of FP6 marine science NoEs (Marine Genomics Europe, MarBEF, EUR-OCEANS). The 2009-2011 strategy and activity plan of EUR-OCEANS will be presented and the involvement of EUR-OCEANS members in other key projects or programmes will

  1. Erratum: Binary neutron stars with arbitrary spins in numerical relativity [Phys. Rev. D 92, 124012 (2015)

    NASA Astrophysics Data System (ADS)

    Tacik, Nick; Foucart, Francois; Pfeiffer, Harald P.; Haas, Roland; Ossokine, Serguei; Kaplan, Jeff; Muhlberger, Curran; Duez, Matt D.; Kidder, Lawrence E.; Scheel, Mark A.; Szilágyi, Béla

    2016-08-01

    The code used in [Phys. Rev. D 92, 124012 (2015)] erroneously computed the enthalpy at the center of the neutron stars. Upon correcting this error, density oscillations in evolutions of rotating neutron stars are significantly reduced (from ˜20 % to ˜0.5 % ). Furthermore, it is possible to construct neutron stars with faster rotation rates.

  2. Comment on ``Quantum key distribution without alternative measurements'' [Phys. Rev. A 61, 052312 (2000)

    NASA Astrophysics Data System (ADS)

    Zhang, Yong-Sheng; Li, Chuan-Feng; Guo, Guang-Can

    2001-03-01

    In a recent paper [A. Cabello, Phys. Rev. A 61, 052312 (2000)], a quantum key distribution protocol based on entanglement swapping was proposed. However, in this Comment, it is shown that this protocol is insecure if Eve uses a special strategy to attack.

  3. [EurSafety Health-Net: MRSA Eradication in Nursing Homes and Home Care - A Practice Report].

    PubMed

    Bergen, P; Rocker, D; Claußen, K; Kluba, J; Vogelsang, E; Vogelsang, G

    2016-01-01

    In 2009 the project EurSafety Health-Net, funded by Interreg IVa, was initiated in order to create a cross-border quality alliance to enhance patient safety in the field of infectious diseases. Within this framework, several studies and projects addressing key topics of infection control were carried out. We describe the two-year project "MRSA decolonisation in care settings (MSP)", which aimed at evaluating a simple and economic way of decolonisation of non-hospitalised MRSA carriers in 2 districts in Lower Saxony. In the course of the project 181 decolonisations of MRSA carriers were performed by nursing homes and nursing services for outpatients in cooperation with the local public health authorities of the districts Ammerland and Grafschaft Bentheim. Of 181 cases 134 were eligible for statistical analysis. The project provided protocols for 2 different starting situations: 1) Continuing and completing a decolonisation treatment subsequent to a hospital stay by nursing services for outpatients or in a nursing home. 2) Starting a decolonisation treatment in a nursing home or by nursing services for outpatients. The carriers were provided with the required materials either by the hospitals (situation 1) or by the local public health authorities (situation 2) free of charge. The decolonisation treatment and the testing were offered only to carriers free of properties deemed as decolonisation obstacles and was applied without involvement of the general practitioner. Short- and long-term success of the 5 day decolonisation treatment was tested afterwards by two swabs (14 days and 6 months after the end of the treatment). The results of the 6-month control swabs showed that 45% of the carriers were successfully decolonised in the long term. All parties involved regarded the procedure of the MSP project as effective with respect to the target. Thus, even after the project was finished, both districts continued applying the MSP protocol. PMID:25951112

  4. Chemistry Teacher Education Coalition: Extending the PhysTEC Model to Chemistry

    NASA Astrophysics Data System (ADS)

    Kirchhoff, Mary

    2012-02-01

    The American Association of Employment in Education reports that chemistry, like physics, faces ``some shortage'' of educators. Inspired by the success of the Physics Teacher Education Coalition (PhysTEC), the American Chemical Society (ACS) is developing the Chemistry Teacher Education Coalition (CTEC) to actively engage chemistry departments in the preparation of future chemistry teachers. Engaging chemistry departments in teacher preparation would increase the number and diversity of well-prepared high school chemistry teachers while catalyzing cultural change within chemistry departments. Many features of PhysTEC, such as a grant competition to create model teacher preparation programs and regular conferences, are directly applicable to chemistry. This presentation will provide an overview of ACS efforts to launch a successful CTEC initiative.

  5. Comment on ``Hydrophobic effects on partial molar volume'' [J. Chem. Phys. 122, 094509 (2005)

    NASA Astrophysics Data System (ADS)

    Graziano, Giuseppe

    2005-10-01

    It is pointed out that the results obtained by Imai and Hirata [ J. Chem. Phys.122, 094509 (2005)] for the partial molar volume of benzene in a detailed model of water and in a hypothetical nonpolar water model should be interpreted with care. By turning off the electrostatic interactions among water molecules, keeping fixed the molar volume and so the liquid number density, in order to produce the hypothetical nonpolar water without H bonds, the size of water molecules increases from about 2.8 to about 3.2Å. This fact is due to the bunching-up effect of H bonds. The consequences of this fact are clarified by means of calculations performed using the analytical expression of the partial molar volume derived by Lee [J. Phys. Chem.87, 112 (1983)] from the scaled particle theory equation of state for hard-sphere mixtures.

  6. Improving Science Teacher Preparation through the APS PhysTEC and NSF Noyce Programs

    NASA Astrophysics Data System (ADS)

    Williams, Tasha; Tyler, Micheal; van Duzor, Andrea; Sabella, Mel

    2013-03-01

    Central to the recruitment of students into science teaching at a school like CSU, is a focus on the professional nature of teaching. The purpose of this focus is twofold: it serves to change student perceptions about teaching and it prepares students to become teachers who value continued professional development and value the science education research literature. The Noyce and PhysTEC programs at CSU place the professional nature of teaching front and center by involving students in education research projects, paid internships, attendance at conferences, and participation in a new Teacher Immersion Institute and a Science Education Journal Reading Class. This poster will focus on specific components of our teacher preparation program that were developed through these two programs. In addition we will describe how these new components provide students with diverse experiences in the teaching of science to students in the urban school district. Supported by the NSF Noyce Program (0833251) and the APS PhysTEC Program.

  7. Comment on “Generalized dispersion relation for electron Bernstein waves in a non-Maxwellian magnetized anisotropic plasma” [Phys. Plasmas 17, 102114 (2010)

    SciTech Connect

    Sharifi, M. Parvazian, A.

    2015-02-15

    In a recent paper [Deeba et al., Phys. Plasmas 17, 102114 (2010)], a generalized dielectric constant for the electron Bernstein waves using non-Maxwellian distribution functions was derived in a collisionless, uniform magnetized plasma. Using the Neumann series expansion for the products of Bessel functions, Deeba, Ahmad, and Murtaza derived the dispersion relations for both kappa and the generalized (r, q) distributions in a straightforward manner. However, their results are questionable, since the Neumann series expansion for the products of Bessel functions is valid for small argument, while for perpendicular propagation, it is necessary to evaluate special integrands for small as well as large arguments.

  8. Comment on the article ``Solitary waves and double layers in an ultra-relativistic degenerate dusty electron-positron-ion plasma'' [Phys. Plasmas 19, 033705 (2012)

    NASA Astrophysics Data System (ADS)

    Akbari-Moghanjoughi, M.

    2012-06-01

    More recently, Roy et al. [Phys. Plasmas 19, 033705 (2012)] have investigated the occurrence of nonlinear solitary and double-layers in an ultrarelativistic dusty electron-positron-ion degenerate plasma using a Sagdeev potential method. They have considered a full parametric examination on Mach-number criteria for existence of such nonlinear excitations using the specific degeneracy limits of Chandrasekhar equation of state (EoS) for Fermi-Dirac plasmas. In this comment, we point-out a misleading extension of polytropic EoS to study the Fermi-Dirac relativistically degenerate plasmas.

  9. Comment on ``The two dimensional motion of a particle in an inverse square potential: Classical and quantum aspects'' [J. Math. Phys. 54, 053509 (2013)

    NASA Astrophysics Data System (ADS)

    Bietenholz, Wolfgang; Chryssomalakos, Chryssomalis; Salgado, Marcelo

    2015-10-01

    We comment on a fatal flaw in the analysis contained in the work of Martínez-y-Romero et al., [J. Math. Phys. 54, 053509 (2013)], which concerns the motion of a point particle in an inverse square potential, and show that most conclusions reached there are wrong. In particular, the manifestly senseless claim that, in the attractive potential case, no bounded orbits exist for negative energies, is traced to a sign error. Several more mistakes, both in the classical and the quantum cases, are pointed out.

  10. Comment on: ‘How much security does Y-00 protocol provide us?’ [Phys. Lett. A 327 (2004) 28

    NASA Astrophysics Data System (ADS)

    Yuen, Horace P.; Kumar, Prem; Corndorf, Eric; Nair, Ranjith

    2005-10-01

    It is claimed by T. Nishioka et al. in [T. Nishioka, T. Hasegawa, H. Ishiziuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28 32] that the security of Y-00 is equivalent to that of a classical stream cipher. In this Letter it is shown that the claim is false in either the use of Y-00 for direct encryption or key generation, in all the parameter ranges it is supposed to operate including those of the experiments reported thus far. The security of Y-00 type protocols is clarified.

  11. Comment on “Geometry effect on the magnetic ordering of geometrically frustrated rectangular and triangular magnets” [Phys. Lett. A 375 (13) (2011) 1548

    NASA Astrophysics Data System (ADS)

    Mól, L. A. S.; Pereira, A. R.; Moura-Melo, W. A.

    2011-07-01

    In a recent letter Li et al. [Phys. Lett. A 375 (2011) 1548] have investigated some geometric effects on the ordering of artificial spin ice materials. They have argued that the system ground-state undergoes a transition when the lattice spacing in one direction is sufficiently larger than in the other. Their results were obtained by evaluating the dipolar interactions using a restrict set of spin pairs. In this comment we show that by taking into account all the dipolar interactions among the spins no ground-state transition is observed.

  12. Comment on the article 'Solitary waves and double layers in an ultra-relativistic degenerate dusty electron-positron-ion plasma'[Phys. Plasmas 19, 033705 (2012)

    SciTech Connect

    Akbari-Moghanjoughi, M.

    2012-06-15

    More recently, Roy et al.[Phys. Plasmas 19, 033705 (2012)] have investigated the occurrence of nonlinear solitary and double-layers in an ultrarelativistic dusty electron-positron-ion degenerate plasma using a Sagdeev potential method. They have considered a full parametric examination on Mach-number criteria for existence of such nonlinear excitations using the specific degeneracy limits of Chandrasekhar equation of state (EoS) for Fermi-Dirac plasmas. In this comment, we point-out a misleading extension of polytropic EoS to study the Fermi-Dirac relativistically degenerate plasmas.

  13. Comment on “A Quantum Network System of QSS-QDC Using χ-Type Entangled States" [Chin. Phys. Lett. 29 (2012) 050303

    NASA Astrophysics Data System (ADS)

    Liu, Zhi-Hao; Chen, Han-Wu; Liu, Wen-Jie; Xu, Juan

    2013-03-01

    Two quantum secret sharing (QSS) protocols in a multiuser quantum direct communication (QDC) network system were put forward by Hong et al. [Chin. Phys. Lett. 29 (2012) 050303]. However, we find that either agent (Bob or Charlie) alone can obtain half the information about the sender's secret without collaboration with the other, which does not satisfy the security requirement of QSS. Moreover, the secret message sent by Alice in the second protocol can be eavesdropped on or its communication can be disturbed by the builder of quantum channels (Trent).

  14. Comment on “Shape transition of unstrained flattest single-walled carbon nanotubes under pressure” [J. Appl. Phys. 115, 044512 (2014)

    SciTech Connect

    Vassilev, Vassil M. Djondjorov, Peter A.; Mladenov, Ivaïlo M.

    2015-05-21

    Recently, Mu et al. [J. Appl. Phys. 115, 044512 (2014)] have developed an analytic approach to describe some special shapes of a single-wall carbon nanotube (SWCNT) under hydrostatic pressure. These authors have found approximate analytic expressions for the parametric equations of the tube cross section profile and its curvature at the convex-to-concave transition pressure using a shell-like 2D continuum model describing the shapes of such nanotubes. In this comment, we provide additional insight into this problem taking into account the exact analytic representation of the shapes that a SWCNT attains when subjected to hydrostatic pressure according to the very same continuum model.

  15. Comment on “The two dimensional motion of a particle in an inverse square potential: Classical and quantum aspects” [J. Math. Phys. 54, 053509 (2013)

    SciTech Connect

    Bietenholz, Wolfgang Chryssomalakos, Chryssomalis Salgado, Marcelo

    2015-10-15

    We comment on a fatal flaw in the analysis contained in the work of Martínez-y-Romero et al., [J. Math. Phys. 54, 053509 (2013)], which concerns the motion of a point particle in an inverse square potential, and show that most conclusions reached there are wrong. In particular, the manifestly senseless claim that, in the attractive potential case, no bounded orbits exist for negative energies, is traced to a sign error. Several more mistakes, both in the classical and the quantum cases, are pointed out.

  16. Comment on “Diffusion of n-type dopants in germanium” [Appl. Phys. Rev. 1, 011301 (2014)

    SciTech Connect

    Cowern, N. E. B. Simdyankin, S.; Goss, J. P.; Napolitani, E.; De Salvador, D.; Bruno, E.; Mirabella, S.; Ahn, C.; Bennett, N. S.

    2015-09-15

    The authors of the above paper call into question recent evidence on the properties of self-interstitials, I, in Ge [Cowern et al., Phys. Rev. Lett. 110, 155501 (2013)]. We show that this judgment stems from invalid model assumptions during analysis of data on B marker-layer diffusion during proton irradiation, and that a corrected analysis fully supports the reported evidence. As previously stated, I-mediated self-diffusion in Ge exhibits two distinct regimes of temperature, T: high-T, dominated by amorphous-like mono-interstitial clusters—i-morphs—with self-diffusion entropy ≈30 k, and low-T, where transport is dominated by simple self-interstitials. In a transitional range centered on 475 °C both mechanisms contribute. The experimental I migration energy of 1.84 ± 0.26 eV reported by the Münster group based on measurements of self-diffusion during irradiation at 550 °C < T < 680 °C further establishes our proposed i-morph mechanism.

  17. Using the PhysX engine for Physics-based Virtual Surgery with Force Feedback

    PubMed Central

    Maciel, Anderson; Halic, Tansel; Lu, Zhonghua; Nedel, Luciana P.; De, Suvranu

    2010-01-01

    Background The development of modern surgical simulators is highly challenging as they must support complex simulation environments. The demand for higher realism in such simulators has driven researchers to adopt physics-based models which are computationally very demanding. This poses a major problem since real time interactions must permit graphical updates of 30 Hz and a much higher rate of 1 kHz for force feedback (haptics). Recently several physics engines have been developed which offer multi-physics simulation capabilities including rigid and deformable bodies, cloth and fluids. While such physics engines provide unique opportunities for the development of surgical simulators, their higher latencies, compared to what is necessary for real time graphics and haptics, offer significant barriers to their use in interactive simulation environments. Methods In this work, we propose solutions to this problem and demonstrate how a multimodal surgical simulation environment may be developed based on NVIDIA’s PhysX physics library. Hence, models that are undergoing relatively low frequency updates in PhysX can exist in an environment that demands much higher frequency updates for haptics. We use a collision handling layer to interface between the physical response provided by PhysX and the haptic rendering device to provide both real time tissue response and force feedback. Results Our simulator integrates a bimanual haptic interface for force-feedback and per-pixel shaders for graphics realism in real time. To demonstrate the effectiveness of our approach, we present the simulation of the Laparoscopic Adjustable Gastric Banding (LAGB) procedure as a case study. Conclusions To develop complex and realistic surgical trainers with realistic organ geometries and tissue properties demands stable physics-based deformation methods which are not always compatible with the interaction level required for such trainers. We have shown that combining different modeling

  18. Comment on 'General nonlocality in quantum fields'[J. Math. Phys. 49, 033513 (2008)

    SciTech Connect

    Wang Haijun

    2010-05-15

    In a recent paper [H.-J. Wang, J. Math. Phys. 49, 033513 (2008)] a complex-geometry model was proposed to interpret the interaction of electromagnetism and the interaction between quarks while the nonlocal effects are involved. In that theoretical frame, from the metric matrix one can obtain a determinant-form condition to describe qualitatively the typical characteristics for the aforementioned interactions. In this comment we attempt to extend this kind of qualitative description to weak interaction by finding out an appropriate metric tensor for it.

  19. Comment on ``Quasirelativistic theory equivalent to fully relativistic theory'' [J. Chem. Phys. 123, 241102 (2005)

    NASA Astrophysics Data System (ADS)

    Filatov, Michael

    2006-09-01

    The connection between the exact quasirelativistic approach developed in the title reference [W. Kutzelnigg and W. Liu, J. Chem. Phys. 123, 241102 (2005)] and the method of elimination of the small component in matrix form developed previously by Dyall is explicitly worked out. An equation that links Hermitian and non-Hermitian formulations of the exact quasirelativistic theory is derived. Besides establishing a kinship between the existing formulations, the proposed equation can be employed for the derivation of new formulations of the exact quasirelativistic theory.

  20. Comment on: ``The hindered rotor density-of-states interpolation function'' [J. Chem. Phys. 106, 6675 (1997)] and ``The hindered rotor density- of-states'' [J. Chem. Phys. 108, 2314 (1998)

    NASA Astrophysics Data System (ADS)

    McClurg, Richard B.

    1999-10-01

    There has been some confusion regarding the various approximations for the hindered rotor partition function and its associated thermodynamic functions and density of states. This comment seeks to clarify the situation by comparing and contrasting the various functions, particularly with regard to the consistent use of reference energies. Only the tabular data of Pitzer and Gwinn [J. Chem. Phys. 10, 428 (1942)] and our analytic function [J. Chem. Phys. 106, 6675 (1997)] have consistent reference energies. The main contribution of our publication is the set of simple, asymptotically correct expressions for the thermodynamic functions. There are similar, but different approximations to the density of states given by Knyazev and co-workers [J. Phys. Chem. A 102, 3916 (1998)] and by me [J. Chem. Phys. 108, 1748 (1998)].

  1. Comment on 'Mathematical and physical aspects of Kappa velocity distribution' [Phys. Plasmas 14, 110702 (2007)

    SciTech Connect

    Hellberg, M. A.; Mace, R. L.; Baluku, T. K.; Kourakis, I.; Saini, N. S.

    2009-09-15

    A recent paper [L.-N. Hau and W.-Z. Fu, Phys. Plasmas 14, 110702 (2007)] deals with certain mathematical and physical properties of the kappa distribution. We comment on the authors' use of a form of distribution function that is different from the 'standard' form of the kappa distribution, and hence their results, inter alia for an expansion of the distribution function and for the associated number density in an electrostatic potential, do not fully reflect the dependence on {kappa} that would be associated with the conventional kappa distribution. We note that their definition of the kappa distribution function is also different from a modified distribution based on the notion of nonextensive entropy.

  2. Comment on ``Mathematical and physical aspects of Kappa velocity distribution'' [Phys. Plasmas 14, 110702 (2007)

    NASA Astrophysics Data System (ADS)

    Hellberg, M. A.; Mace, R. L.; Baluku, T. K.; Kourakis, I.; Saini, N. S.

    2009-09-01

    A recent paper [L.-N. Hau and W.-Z. Fu, Phys. Plasmas 14, 110702 (2007)] deals with certain mathematical and physical properties of the kappa distribution. We comment on the authors' use of a form of distribution function that is different from the "standard" form of the kappa distribution, and hence their results, inter alia for an expansion of the distribution function and for the associated number density in an electrostatic potential, do not fully reflect the dependence on κ that would be associated with the conventional kappa distribution. We note that their definition of the kappa distribution function is also different from a modified distribution based on the notion of nonextensive entropy.

  3. PREFACE: International Symposium "Nanoscience and Quantum Physics 2011" (nanoPHYS'11)

    NASA Astrophysics Data System (ADS)

    Saito, Susumu; Tanaka, Hidekazu; Nakamura, Takashi; Nakamura, Masaaki

    2011-07-01

    Quantum physics has developed modern views of nature for more than a century. In addition to this traditional role, quantum physics has acquired new significance in the 21st century as the field responsible for driving and supporting nanoscience research, which will have even greater importance in the future because nanoscience will be the academic foundation for new technologies. The Department of Physics, Tokyo Institute of Technology, are now conducting a "Nanoscience and Quantum Physics" project (Physics G-COE project) supported by the Global Center of Excellence Program of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT) in order to promote research and education in these important academic fields. The International Symposium on Nanoscience and Quantum Physics, held in Tokyo, Japan, 26-28 January 2011 (nanoPHYS'11) was organized by the Physics G-COE project of the Tokyo Institute of Technology to provide an international forum for the open exchange of topical information and for stimulating discussion on novel concepts and future prospects of nanoscience and quantum physics. There were a total of 118 papers including 34 invited papers. This nanoPHYS'11 is the fourth symposium of this kind organized by the Tokyo Institute of Technology. Topics focused on in the symposium included: Category 1: Novel nanostructure (Nanowires, Nanotubes, Spin-related structure, etc) Category 2: Novel transport and electronic properties (Graphene, Topological insulators, Coherent control, etc) Category 3: Electronic and optical properties of nanostructure Category 4: Fundamental physics and new concept in quantum physics Category 5: Quantum Physics - Quantum information Category 6: Quantum Physics - Nuclear and Hadron Physics Category 7: Quantum Physics - Astrophysics, etc All the papers submitted to this issue have been reviewed under a stringent refereeing process, according to the normal rules of this Journal. The editors are grateful to all the

  4. Comment on "Existence domains of slow and fast ion-acoustic solitons in two-ion space plasmas" [Phys. Plasmas 22, 032313 (2015)

    NASA Astrophysics Data System (ADS)

    Olivier, C. P.; Maharaj, S. K.; Bharuthram, R.

    2016-06-01

    In a series of papers by Maharaj et al., including "Existence domains of slow and fast ion-acoustic solitons in two-ion space plasmas" [Phys. Plasmas 22, 032313 (2015)], incorrect expressions for the Sagdeev potential are presented. In this paper, we provide the correct expression of the Sagdeev potential. The correct expression was used to generate the numerical results for the above-mentioned series of papers, so that all results and conclusions are correct, despite the wrong Sagdeev potential expressions printed in the papers. The correct expression of the Sagdeev potential presented here is a very useful generic expression in the sense that a single expression can be used to study nonlinear structures associated with any acoustic mode, despite the fact that the supersonic and subsonic species would vary if solitons associated with different linear modes are studied.

  5. Response to “Comment on ‘Twin symmetry texture of energetically condensed niobium thin films on sapphire substrate’ ” [J. Appl. Phys. 112, 016101 (2012)

    DOE PAGESBeta

    Zhao, X.; Philips, L.; Reece, C. E.; Seo, Kang; Krishnan, M.; Valderrama, E.

    2012-07-01

    Welander is correct about the misidentified crystal-directions in the top-view sapphire lattice (Fig. 4 [Zhao et al., J. Appl. Phys. 110, 033523 (2011)]). He is also correct about the misorientation of the pole figures in Fig. 4. In Fig. 1 of this response, we have corrected these errors. Perhaps because of these errors, Welander misconstrued our discussion of the Nbcrystal growth as claiming a new 3D registry. That was not our intention. Rather, we wished to highlight the role of energetic condensation that drives low-defect crystal growth by a combination of non-equilibrium sub-plantation that disturbs the substrate lattice and thermalmore » annealing that annihilates defects and promotes large-grain crystal growth.« less

  6. Comment on: ``Disentangling density and temperature effects in the viscous slowing down of glass forming liquids'' [J. Chem. Phys. 120, 6135 (2004)

    NASA Astrophysics Data System (ADS)

    Roland, C. M.; Casalini, R.

    2004-12-01

    Recently, Tarjus et al. [G. Tarjus, D. Kivelson, S. Mossa, and C. Alba-Simionesco, J. Chem. Phys. 120, 6135 (2004)] concluded from a review of data for a variety of glass formers that the supercooled dynamics are almost invariably dominated by temperature T, rather than by density ρ. By including additional published data into such a compilation, we show that for van der Waals molecular liquids, the dynamics near Tg are in fact governed as much by density as by temperature. Moreover, relaxation times measured at various temperatures and pressures can be superimposed by plotting as a function ργ/T. This scaling form can arise from an assumed inverse power law for the intermolecular repulsive potential, with γ a material constant.

  7. PyDecay/GraphPhys: A Unified Language and Storage System for Particle Decay Process Descriptions

    SciTech Connect

    Dunietz, Jesse N.; /MIT /SLAC

    2011-06-22

    To ease the tasks of Monte Carlo (MC) simulation and event reconstruction (i.e. inferring particle-decay events from experimental data) for long-term BaBar data preservation and analysis, the following software components have been designed: a language ('GraphPhys') for specifying decay processes, common to both simulation and data analysis, allowing arbitrary parameters on particles, decays, and entire processes; an automated visualization tool to show graphically what decays have been specified; and a searchable database storage mechanism for decay specifications. Unlike HepML, a proposed XML standard for HEP metadata, the specification language is designed not for data interchange between computer systems, but rather for direct manipulation by human beings as well as computers. The components are interoperable: the information parsed from files in the specification language can easily be rendered as an image by the visualization package, and conversion between decay representations was implemented. Several proof-of-concept command-line tools were built based on this framework. Applications include building easier and more efficient interfaces to existing analysis tools for current projects (e.g. BaBar/BESII), providing a framework for analyses in future experimental settings (e.g. LHC/SuperB), and outreach programs that involve giving students access to BaBar data and analysis tools to give them a hands-on feel for scientific analysis.

  8. Erratum: Studying the precision of ray tracing techniques with Szekeres models [Phys. Rev. D 92, 023532 (2015)

    NASA Astrophysics Data System (ADS)

    Koksbang, S. M.; Hannestad, S.

    2015-09-01

    This erratum serves to give corrections of two errors made in Koksbang and Hannestad [Phys. Rev. D, 92, 023532 (2015)]. One error consists of having used the expression for the Doppler convergence for a flat background to study the convergence on curved backgrounds. The other error which was made, is a typo in the numerical code used to study the convergence in onion models with curved backgrounds. After correcting this typo, the results of Sec. VI A in Koksbang and Hannestad [Phys. Rev. D, 92, 023532 (2015)] were recomputed. Contrary to the original results, the new results show that the ray-tracing scheme studied in Koksbang and Hannestad [Phys. Rev. D, 92, 023532 (2015)] can reproduce the exact results in LTB onion models very well. The corrections and new results are described more elaborately below.

  9. Erratum: Diffusive quantum criticality in three-dimensional disordered Dirac semimetals [Phys. Rev. B 90, 241112(R) (2014)

    NASA Astrophysics Data System (ADS)

    Roy, Bitan; Das Sarma, S.

    2016-03-01

    We correct erroneous conclusions from our previous article [Phys. Rev. B 90, 241112(R) (2014), 10.1103/PhysRevB.90.241112] regarding the values of various critical exponents, calculated to two-loop order. Furthermore, from a three-loop renormalization group flow equation, we argue, that ɛ -expansion near two spatial dimensions, with ɛ =d -2 , may not be reliable to address the critical properties of the disorder-driven Dirac semimetal-metal quantum phase transition in d =3 .

  10. 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}

  11. Comments on ''theory of dissipative density-gradient-driven turbulence in the tokamak edge'' (Phys. Fluids 28, 1419 (1985))

    SciTech Connect

    Krommes, J.A.

    1985-11-01

    The author critiques the model of tokamak edge turbulence by P.W. Terry and P.H. Diamond (Phys. Fluids 28, 1419, 1985). The critique includes a discussion of the physical basis, consistency and quantitative accuracy of the Terry-Diamond model. 19 refs. (WRF)

  12. Comment on ``A proposal for in vitro/GFR molecular erythema action spectrum'' [J. Appl. Phys. 104, 034701 (2008)

    NASA Astrophysics Data System (ADS)

    Björn, Lars Olof; de Gruijl, Frank R.; Diffey, Brian; Norval, Mary

    2009-06-01

    The recent article by de Souza, Lorenzini and Rizzatti [J. A. V. de Souza, F. Lorenzini, and M. R. Rizatti, J. Appl. Phys. 104, 034701 (2008)] in this journal needs corrections and clarifications on several points. The model used by them is not suitable for the study of erythema.

  13. Comment on "A new approach to optimum design in thermoelectric cooling systems" [J. Appl. Phys. 80, 5494 (1996)

    NASA Astrophysics Data System (ADS)

    Chen, Jincan; Schouten, Jan A.

    1997-12-01

    It is pointed out that there are some errors existing in a recent investigation in this journal [M. Yamanishi, J. Appl. Phys. 80, 5494 (1996)]. The correct results are given so that one can better understand the performance of real thermoelectric cooler systems.

  14. Computational Fluid Dynamics Simulation of Hydrodynamics and Stresses in the PhEur/USP Disintegration Tester Under Fed and Fasted Fluid Characteristics.

    PubMed

    Kindgen, Sarah; Wachtel, Herbert; Abrahamsson, Bertil; Langguth, Peter

    2015-09-01

    Disintegration of oral solid dosage forms is a prerequisite for drug dissolution and absorption and is to a large extent dependent on the pressures and hydrodynamic conditions in the solution that the dosage form is exposed to. In this work, the hydrodynamics in the PhEur/USP disintegration tester were investigated using computational fluid dynamics (CFD). Particle image velocimetry was used to validate the CFD predictions. The CFD simulations were performed with different Newtonian and non-Newtonian fluids, representing fasted and fed states. The results indicate that the current design and operating conditions of the disintegration test device, given by the pharmacopoeias, are not reproducing the in vivo situation. This holds true for the hydrodynamics in the disintegration tester that generates Reynolds numbers dissimilar to the reported in vivo situation. Also, when using homogenized US FDA meal, representing the fed state, too high viscosities and relative pressures are generated. The forces acting on the dosage form are too small for all fluids compared to the in vivo situation. The lack of peristaltic contractions, which generate hydrodynamics and shear stress in vivo, might be the major drawback of the compendial device resulting in the observed differences between predicted and in vivo measured hydrodynamics. PMID:26017815

  15. Comment on ``Model of saturated lithium ammonia as a single-component liquid metal'' [J. Chem. Phys. 124, 074702 (2006)

    NASA Astrophysics Data System (ADS)

    Chuev, Gennady N.; Quémerais, Pascal

    2008-01-01

    We demonstrate in this Comment that the theory of simple metals applied to the saturated Li -NH3 solution in the titled paper [U. Pinsook and S. Hannongbua, J. Chem. Phys.124, 074702 (2006)] should account for the peculiarities of the solution, namely, the high solvent polarizability and different energy scales for ion-ion and electron-electron interactions. Calculations not taking into account these peculiarities contradict the experimental phase diagram of the Li -NH3 solution.

  16. Comments on ``Gazeau-Klauder coherent states for trigonometric Rosen-Morse potential'' [J. Math. Phys. 49, 022104 (2008)

    NASA Astrophysics Data System (ADS)

    Fakhri, H.; Dehghani, A.

    2008-05-01

    In a recently published paper in this journal [A. Cheaghlou and O. Faizy, J. Math. Phys. 49, 022104 (2008)], the authors introduce the Gazeau-Klauder coherent states for the trigonometric Rosen-Morse potential as an infinite superposition of the wavefunctions. It is shown that their proposed measure to realize the resolution of the identity condition is not positive definite. Consequently, the claimed coherencies for the trigonometric Rosen-Morse wavefunctions cannot actually exist.

  17. Corrigendum to “Robust limits on Lorentz violation from gamma-ray bursts” [Astropart. Phys. 25 (2006) 402

    NASA Astrophysics Data System (ADS)

    Ellis, John; Mavromatos, N. E.; Nanopoulos, D. V.; Sakharov, A. S.; Sarkisyan, E. K. G.

    2008-03-01

    We correct the fitting formula used [J.R. Ellis, N.E. Mavromatos, D.V. Nanopoulos, A.S. Sakharov, E.K.G. Sarkisyan, Astropart. Phys. 25 (2006) 402. Available from: arxiv:] to obtain a robust limit on a violation of Lorentz invariance that depends linearly on the photon energy. The correction leads to a slight increase of the limit on the scale of the violation, to M > 1.4 ×1016GeV .

  18. Comment on "Non-thermal mechanism of weak microwave fields influence on neurons" [J. Appl. Phys. 114, 104701 (2013)

    NASA Astrophysics Data System (ADS)

    Pekker, M.; Shneider, M. N.

    2016-02-01

    This comment is directly related to previously published work [M. N. Shneider and M. Pekker, J. Appl. Phys. 114, 104701 (2013)], in which we outlined the effect of a non-thermal mechanism of microwave radiation on the activity of neural tissue. In this note, we provide more realistic estimates of the longitudinal sound velocity in the lipid membranes and the corresponding estimates of the microwave resonance frequencies.

  19. Comment on 'Power loss in open cavity diodes and a modified Child-Langmuir law' [Phys. Plasmas 12, 093102 (2005)

    SciTech Connect

    Swanekamp, S. B.; Ottinger, P. F.

    2007-09-15

    In this Comment, it is shown that no modification of the Child-Langmuir law [Phys. Rev.32, 492 (1911); Phys. Rev. 2, 450 (1913)] is necessary to treat the space-charge-limited flow from a diode with an open boundary as reported in Phys. Plasmas 12, 093102 (2005). The open boundary condition in their simulations can be represented by a voltage source and a resistor whose value is the vacuum-wave impedance of the opening. The diode can be represented as a variable resistor whose value depends on the voltage drop across the diode (as measured by the line integral of E across the diode gap). This is a simple voltage-divider circuit whose analysis shows that the real diode voltage drops as the vacuum-wave impedance increases. Furthermore, it is shown that in equilibrium, the voltage drop between the anode and cathode is independent of the path chosen for the line integral of the electric field so that E=-{nabla}{phi} is valid. In this case, the equations of electrostatics are applicable. This clearly demonstrates that the electric field is electrostatic and static fields DO NOT RADIATE. It is shown that the diode voltage drops as the vacuum wave impedance increases and the current drops according to the Child-Langmuir law. Therefore, the observed drop in circuit current can be explained by a real drop in voltage across the diode and not an effective drop as claimed by the authors.

  20. Response to Comment on '#28;Twin Symmetry Texture of Energetically Condensed 2 Niobium Thin Films on Sapphire Substrate' #29; [J. Appl. Phys. 110, 033523(2011)

    SciTech Connect

    Xin Zhao, Charles Reece, Phillips Larry, Mahadevan Krishnan, Kang Seo

    2012-07-01

    Welander commented that in our article [J. Appl. Phys. 110, 033523(2011)] , Zhao et al claim to have found a new three-dimensional (3D) relationship for niobium-on-sapphire epitaxy”. Welander might have misunderstood the purpose of our article, which was to show that energetic condensation of Nb on sapphire drives crystal growth that is quite distinct from the type of epitaxy encountered in lower energy deposition. Welander is correct about the misidentified crystal-directions in the top-view sapphire lattice (Fig.4[ref.1]). He is also correct about the misorientation of the pole figures in Fig4[ref.1]. In Fig.1 of this response, we have corrected these errors. Perhaps because of these errors, Welander misconstrued our discussion of the Nb crystal growth as claiming a new 3D registry. That was not our intention. Rather, we wished to highlight the role of energetic condensation that drives low-defect crystal growth by a combination of non-equilibrium sub-plantation that disturbs the substrate lattice and thermal annealing that annihilates defects and promotes large-grain crystal growth.

  1. Reply to 'Comment on 'All quantum observables in a hidden-variable model must commute simultaneously'' [Phys. Rev. A 73, 066101 (2006)

    SciTech Connect

    Malley, J. D.; Fine, A.

    2006-06-15

    Nagata [Phys. Rev. A 73, 066101 (2006)] questions whether a general no-go theorem of Malley [Phys. Rev. A 69, 022118 (2004)] applies to local hidden variables and outlines a 'counterexample.' In fact this is not a counterexample at all, but in seeing why it fails we clarify the significance of Malley's result and its relation to other no-go theorems.

  2. Same Initial States Attack in Yang et al.'s Quantum Private Comparison Protocol and the Improvement

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Jie; Liu, Chao; Liu, Zhi-Hao; Liu, Jing-Fa; Geng, Huan-Tong

    2014-01-01

    In Yang et al.'s literatures (J. Phys. A: Math. 42, 055305, 2009; J. Phys. A: Math. 43, 209801, 2010), a quantum private comparison protocol based on Bell states and hash function is proposed, which aims to securely compare the equality of two participants' information with the help of a dishonest third party (TP). However, this study will point out their protocol cannot resist a special kind of attack, TP's same initial states attack, which is presented in this paper. That is, the dishonest TP can disturb the comparison result without being detected through preparing the same initial states. Finally, a simple improvement is given to avoid the attack.

  3. Comment on ``Free energy simulations of single and double ion occupancy in gramicidin A'' [J. Chem. Phys. 126, 105103 (2007)

    NASA Astrophysics Data System (ADS)

    Roux, Benoît; Andersen, Olaf S.; Allen, Toby W.

    2008-06-01

    In a recent article published by Bastug and Kuyucak [J. Chem. Phys.126, 105103 (2007)] investigated the microscopic factors affecting double ion occupancy in the gramicidin channel. The analysis relied largely on the one-dimensional potential of mean force of ions along the axis of the channel (the so-called free energy profile of the ion along the channel axis), as well as on the calculation of the equilibrium association constant of the ions in the channel binding sites. It is the purpose of this communication to clarify this issue.

  4. Comment on ``Experimental observation of carbon dioxide reduction in exhaust gas from hydrocarbon fuel burning'' [Phys. Plasmas 16, 114502 (2009)

    NASA Astrophysics Data System (ADS)

    Byun, Youngchul; Shin, Dong Nam

    2010-01-01

    The following comments are intended to clarify whether it is possible to convert CO2 into C+O2 by supplying just one-twentieth of energy required thermodynamically, only under the condition that the negative high voltage of dc is applied to the gas stream perpendicularly, in a recent article by Uhm and Kim [H. S. Uhm and C. H. Kim, Phys. Plasmas 16, 114502 (2009)]. Of particular concern is the disobedience of the first and second laws of thermodynamics together with the indistinct measurement of experimental data.

  5. Comment on ``Dynamics of glass-forming liquids. XIII. Microwave heating in slow motion'' [J. Chem. Phys. 130, 194509 (2009)

    NASA Astrophysics Data System (ADS)

    Johari, G. P.

    2012-07-01

    Critical reading of the dielectric method and data in the paper [W. Huang and R. Richert, J. Chem. Phys. 130, 194509 (2009)], 10.1063/1.3139519 showed that (i) the large inter-electrode area of the Teflon spacer used in the dielectric cell affected the spectral data and (ii) the measured Δɛ of propylene carbonate after making the spacer area correction is 1.8-times the known value, indicating errors from unknown sources. This puts into question their support for the dynamic heterogeneity view, and their inference on the magnitude of configurational heat capacity.

  6. Comment on 'Experimental observation of carbon dioxide reduction in exhaust gas from hydrocarbon fuel burning' [Phys. Plasmas 16, 114502 (2009)

    SciTech Connect

    Byun, Youngchul; Shin, Dong Nam

    2010-01-15

    The following comments are intended to clarify whether it is possible to convert CO{sub 2} into C+O{sub 2} by supplying just one-twentieth of energy required thermodynamically, only under the condition that the negative high voltage of dc is applied to the gas stream perpendicularly, in a recent article by Uhm and Kim [H. S. Uhm and C. H. Kim, Phys. Plasmas 16, 114502 (2009)]. Of particular concern is the disobedience of the first and second laws of thermodynamics together with the indistinct measurement of experimental data.

  7. Olea europaea leaf (Ph.Eur.) extract as well as several of its isolated phenolics inhibit the gout-related enzyme xanthine oxidase.

    PubMed

    Flemmig, J; Kuchta, K; Arnhold, J; Rauwald, H W

    2011-05-15

    In Mediterranean folk medicine Olea europaea L. leaf (Ph.Eur.) preparations are used as a common remedy for gout. In this in vitro study kinetic measurements were performed on both an 80% ethanolic (v/v) Olea europaea leaf dry extract (OLE) as well as on nine of its typical phenolic constituents in order to investigate its possible inhibitory effects on xanthine oxidase (XO), an enzyme well known to contribute significantly to this pathological process. Dixon and Lineweaver-Burk plot analysis were used to determine K(i) values and the inhibition mode for the isolated phenolics, which were analysed by RP-HPLC for standardisation of OLE. The standardised OLE as well as some of the tested phenolics significantly inhibited the activity of XO. Among these, the flavone aglycone apigenin exhibited by far the strongest effect on XO with a K(i) value of 0.52 μM. In comparison, the known synthetic XO inhibitor allopurinol, used as a reference standard, showed a K(i) of 7.3 μM. Although the phenolic secoiridoid oleuropein, the main ingredient of the extract (24.8%), had a considerable higher K(i) value of 53.0 μM, it still displayed a significant inhibition of XO. Furthermore, caffeic acid (K(i) of 11.5 μM; 1.89% of the extract), luteolin-7-O-β-D-glucoside (K(i) of 15.0 μM; 0.86%) and luteolin (K(i) of 2.9 μM; 0.086%) also contributed significantly to the XO inhibiting effect of OLE. For oleuropein, a competitive mode of inhibition was found, while all other active substances displayed a mixed mode of inhibition. Tyrosol, hydroxytyrosol, verbascoside, and apigenin-7-O-β-D-glucoside, which makes up for 0.3% of the extract, were inactive in all tested concentrations. Regarding the pharmacological in vitro effect of apigenin-7-O-β-D-glucoside, it has to be considered that it is transformed into the active apigenin aglycone in the mammalian body, thus also contributing substantially to the anti-gout activity of olive leaves. For the first time, this study provides a

  8. PhysBinder: Improving the prediction of transcription factor binding sites by flexible inclusion of biophysical properties.

    PubMed

    Broos, Stefan; Soete, Arne; Hooghe, Bart; Moran, Raymond; van Roy, Frans; De Bleser, Pieter

    2013-07-01

    The most important mechanism in the regulation of transcription is the binding of a transcription factor (TF) to a DNA sequence called the TF binding site (TFBS). Most binding sites are short and degenerate, which makes predictions based on their primary sequence alone somewhat unreliable. We present a new web tool that implements a flexible and extensible algorithm for predicting TFBS. The algorithm makes use of both direct (the sequence) and several indirect readout features of protein-DNA complexes (biophysical properties such as bendability or the solvent-excluded surface of the DNA). This algorithm significantly outperforms state-of-the-art approaches for in silico identification of TFBS. Users can submit FASTA sequences for analysis in the PhysBinder integrative algorithm and choose from >60 different TF-binding models. The results of this analysis can be used to plan and steer wet-lab experiments. The PhysBinder web tool is freely available at http://bioit.dmbr.ugent.be/physbinder/index.php. PMID:23620286

  9. Comment on “Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma” [Phys. Plasmas 20, 072703 (2013)

    SciTech Connect

    Habibi, M.; Ghamari, F.

    2014-06-15

    Patil and Takale in their recent article [Phys. Plasmas 20, 072703 (2013)], by evaluating the quantum dielectric response in thermal quantum plasma, have modeled the relativistic self-focusing of Gaussian laser beam in a plasma. We have found that there are some important shortcomings and fundamental mistakes in Patil and Takale [Phys. Plasmas 20, 072703 (2013)] that we give a brief description about them and refer readers to important misconception about the use of the Fermi temperature in quantum plasmas, appearing in Patil and Takale [Phys. Plasmas 20, 072703 (2013)].

  10. Comment on ``On the role of dissipation on the Casimir-Polder potential between molecules in dielectric media'' [J. Chem. Phys. 133, 164501 (2010)

    NASA Astrophysics Data System (ADS)

    Dalvit, D. A. R.; Milonni, P. W.

    2011-07-01

    J. J. Rodriguez and A. Salam [J. Chem. Phys. 133, 164501 (2010)], 10.1063/1.3495954 find discrepancies between their calculation and a previously published one [S. Spagnolo, D. A. R. Dalvit, and P. W. Milonni, Phys. Rev. A 75, 052117 (2007)], 10.1103/PhysRevA.75.052117 for the van der Waals interaction of two guest molecules in a host dielectric medium. We trace these discrepancies to what we regard as fundamental errors in the calculation by Rodriguez and Salam.

  11. Comment on ‘Using non-positive maps to characterize entanglement witnesses’ by Mozrzymas et al (2015 J. Phys. A: Math. Theor. 48 395302)

    NASA Astrophysics Data System (ADS)

    Chruściński, Dariusz; Sarbicki, Gniewomir

    2016-05-01

    We show that the non-positive maps used by authors are uniquely defined in terms of positive maps. This way we restore the well known result that entanglement witnesses are fully characterized by positive maps which are not completely positive.

  12. ALS - resources

    MedlinePlus

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

  13. ALS Association

    MedlinePlus

    ... ALS. Find Out How Our Mission Leading the fight to treat and cure ALS through global research ... you participate, advocate, and donate, you advance the fight to find the cure and lead us toward ...

  14. 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.

  15. 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.

  16. Comment on "Laser ablation of Cu and plume expansion into 1 atm ambient gas" [J. Appl. Phys. 97, 063305 (2005)

    NASA Astrophysics Data System (ADS)

    Autrique, D.; Alexiades, V.

    2014-04-01

    A hydrodynamic model used for the study of ns-laser ablation in an ambient environment [Z. Chen and A. Bogaerts, J. Appl. Phys. 97, 063305 (2005)] was investigated and compared with an in-house developed code. After a detailed analysis of the source code and the underlying theoretical framework, significant flaws were detected in the model. It was found that the respective model as well as the ones presented in some earlier and later manuscripts is not able to simulate the ablation process, i.e., target heating, material removal, breakdown, plasma formation, and plume expansion, self-consistently. The present findings indicate that their use should be discontinued when modeling the overall ablation process. Based on existing models in the literature, alternative theoretical pathways are proposed to facilitate future computational studies of ns-laser ablation.

  17. Comment on ``On the tensile strength distribution of multiwalled carbon nanotubes'' [Appl. Phys. Lett. 87, 203106 (2005)

    NASA Astrophysics Data System (ADS)

    Lu, Chunsheng

    2008-05-01

    In a recent letter, Barber, Andrews, Schadler, and Wagner, Appl. Phys. Lett. 87, 203106 (2005). indicated that Weibull-Poisson statistics could accurately model the nanotube tensile strength data, and then concluded that the apparent strengthening mechanism in a multiwalled carbon nanotube (MWCNT) grown by chemical vapor deposition (CVD) is most likely caused by an enhanced interaction between the walls of the nanotube. In this comment, we show that their conclusion seems to be inconsistent with the assumption introduced in the data analysis by using a two-parameter Weibull distribution. Further statistical analysis provides a new explanation on the scattered strengths of MWCNTs. The effectiveness of Weibull-Poisson statistics at nanoscales is also discussed.

  18. Response to 'Comment on 'Pinch current limitation effect in plasma focus'' [Appl. Phys. Lett. 94, 076101 (2009)

    SciTech Connect

    Lee, S.; Saw, S. H.

    2009-02-16

    The main point of the comment [Appl. Phys. Lett. 94, 076101 (2009)] is that Eq. (2) and consequentially Eq. (3) of the commented paper [Appl. Phys. Lett. 92, 021503 (2008)] require correction. The alternative equation suggested in the comment is derived using Kirchhoff's voltage rule. The comment consider only the energy distribution in the inductive components and the resultant equation confirms a progressive lowering of the I{sub pinch}/I{sub peak} ratio as the static inductance L{sub 0} is reduced, lowering from 0.87 to 0.31 as L{sub 0} is reduced from 100 to 5 nH according to the revised formula corresponding to Eq. (3), compared to 0.63-0.25 according to Eq. (3). This progressive lowering of the ratio I{sub pinch}/I{sub peak} due to the inductive energy distribution is one of two factors responsible for the pinch current limitation. The other factor is the progressive reduction in the L-C interaction time compared to the current dip duration denoted by {delta}{sub cap} in Eq. (2). The comment does not deal with {delta}{sub cap} at all; hence, its conclusion based on inductive energy distribution only is not useful, since in the low L{sub 0} region when pinch current limitation begins to manifest, {delta}{sub cap} becomes more and more the dominant factor. In any case, the results of the paper do not depend on Eqs. (2) and (3), which are used in the paper only for illustrative purposes.

  19. Comment on ``Multiconfiguration Dirac-Fock energy levels and radiative rates for Br-like tungsten'' by S. Aggarwal, A.K.S. Jha, and M. Mohan [Can. J. Phys. 91, 394 (2013)

    NASA Astrophysics Data System (ADS)

    Aggarwal, Kanti M.; Keenan, Francis P.

    2014-06-01

    We report calculations of energy levels and oscillator strengths for transitions in W XL, undertaken with the general-purpose relativistic atomic structure package ({\\sc grasp}) and flexible atomic code ({\\sc fac}). Comparisons are made with existing results and the accuracy of the data is assessed. Discrepancies with the most recent results of S. Aggarwal et al. [Can. J. Phys. {\\bf 91} (2013) 394] are up to 0.4 Ryd and up to two orders of magnitude for energy levels and oscillator strengths, respectively. Discrepancies for lifetimes are even larger, up to four orders of magnitude for some levels. Our energy levels are estimated to be accurate to better than 0.5% (i.e. 0.2 Ryd), whereas results for oscillator strengths and lifetimes should be accurate to better than 20%.

  20. Renormalization scheme dependence of the two-loop QCD corrections to the neutral Higgs-boson masses in the MSSM

    NASA Astrophysics Data System (ADS)

    Borowka, S.; Hahn, T.; Heinemeyer, S.; Heinrich, G.; Hollik, W.

    2015-09-01

    Reaching a theoretical accuracy in the prediction of the lightest MSSM Higgs-boson mass, , at the level of the current experimental precision requires the inclusion of momentum-dependent contributions at the two-loop level. Recently two groups presented the two-loop QCD momentum-dependent corrections to (Borowka et al., Eur Phys J C 74(8):2994, 2014; Degrassi et al., Eur Phys J C 75(2):61, 2015), using a hybrid on-shell- scheme, with apparently different results. We show that the differences can be traced back to a different renormalization of the top-quark mass, and that the claim in Ref. Degrassi et al. (Eur Phys J C 75(2):61, 2015) of an inconsistency in Ref. Borowka et al. (Eur Phys J C 74(8):2994, 2014) is incorrect. We furthermore compare consistently the results for obtained with the top-quark mass renormalized on-shell and . The latter calculation has been added to the FeynHiggs package and can be used to estimate missing higher-order corrections beyond the two-loop level.

  1. Comment on ‘An educational path for the magnetic vector potential and its physical implications’

    NASA Astrophysics Data System (ADS)

    Heras, José A.

    2014-03-01

    In their recent paper, Barbieri et al (2013 Eur. J. Phys. 34 1209) proposed an educational path for the magnetic vector potential. In this comment I point out that this educational path involves several inconsistencies and is therefore unattractive from a pedagogical point of view.

  2. On the Heat Transfer through a Solid Slab Heated Uniformly and Continuously on One of Its Surfaces

    ERIC Educational Resources Information Center

    Marin, E.; Lara-Bernal, A.; Calderon, A.; Delgado-Vasallo, O.

    2011-01-01

    Some peculiarities of the heat transfer through a sample that is heated by the superficial absorption of light energy under continuous uniform illumination are discussed. We explain, using a different approach to that presented in a recent article published in this journal (Salazar "et al" 2010 "Eur. J. Phys." 31 1053-9), that the front surface of…

  3. Erratum to “The dimension formula for the Lorenz attractor” [Phys. Lett. A 375 (8) (2011) 1179

    NASA Astrophysics Data System (ADS)

    Leonov, G. A.; Pogromsky, A. Yu.; Starkov, K. E.

    2012-10-01

    In our recent publication (G.A. Leonov et al., 2011 [1]) we formulated a result on Lyapunov dimension formula for the Lorenz system. The proof of this result contains a flaw which is corrected in this Erratum.

  4. Reply to: “Comment on: ‘How much security does Y-00 protocol provide us?’ ” [Phys. Lett. A 346 (2005) 1

    NASA Astrophysics Data System (ADS)

    Nishioka, Tsuyoshi; Hasegawa, Toshio; Ishizuka, Hirokazu; Imafuku, Kentaro; Imai, Hideki

    2005-10-01

    In a recent paper titled “Comment on: ‘How much security does the Y-00 protocol provide us?’ ” [H.P. Yuen, P. Kumar, E. Corndorf, Phys. Lett. A 346 (2005) 1 6], the authors critically examine our idea [T. Nishioka, T. Hasegawa, H. Ishizuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28 32] that the Y-00 protocol is essentially as secure as classical stream ciphers. We clarify our idea in more detail than our previous paper and show that the Y-00 protocol can be considered as a classical non-random stream cipher, as was claimed in [T. Nishioka, T. Hasegawa, H. Ishizuka, K. Imafuku, H. Imai, Phys. Lett. A 327 (2004) 28 32]. We also provide an analysis on key generation with the improved Y-00 protocol, which is implemented with weak coherent states.

  5. Comment on "Ion distribution function in a plasma with uniform electric field" [Phys. Plasmas 19, 113703 (2012)].

    NASA Astrophysics Data System (ADS)

    Mustafaev, Alex; Sukhomlinov, Vladimir; Timofeev, Nikolay

    2016-08-01

    The comparison between experimental data of ion distribution function at the parent gas plasma obtained by the authors and results of calculations presented by Lampe et al. are considered. It is shown that the experimental and calculated angular distributions of ions in the case at least of argon differ considerably. The analysis of Lampe et al. assumptions showed that the main reasons of these discrepancies were the assumptions of ion distribution function independence on field orientation and independence of charge exchange cross-section on the relative velocity of ion and atom.

  6. 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.

  7. Comment on ``Barut-Girardello and Klauder-Perelomov coherent states for the Kravchuk functions'' [J. Math. Phys. 48, 112106 (2007)

    NASA Astrophysics Data System (ADS)

    Fakhri, H.; Dehghani, A.

    2008-04-01

    We call attention to the misconstructions in a paper recently published in this journal [A. Chenaghlou and O. Faizy, J. Math. Phys. 48, 112106 (2007)]. It is shown that the constructed Barut-Girardello coherent states are problematic from the view points of the definition and the measure. The claimed coherencies for the Kravchuk functions cannot actually exist.

  8. Note: Derivation of two-photon circular dichroism—Addendum to “Two-photon circular dichroism” [J. Chem. Phys. 62, 1006 (1975)

    SciTech Connect

    Friese, Daniel H.

    2015-09-07

    This addendum shows the detailed derivation of the fundamental equations for two-photon circular dichroism which are given in a very condensed form in the original publication [I. Tinoco, J. Chem. Phys. 62, 1006 (1975)]. In addition, some minor errors are corrected and some of the derivations in the original publication are commented.

  9. Erratum to: “Weak corrections to gluon-induced top antitop hadro-production” [Phys. Lett. B 639 (2006) 513

    NASA Astrophysics Data System (ADS)

    Moretti, S.; Nolten, M. R.; Ross, D. A.

    2008-03-01

    This is an Erratum to a Letter of ours [S. Moretti, M.R. Nolten, D.A. Ross, Phys. Lett. B 639 (2006) 513]. After its publication, we have discovered a mistake in a numerical program that affects the results presented therein. We provide here the corrected version.

  10. A few remarks on the paper ``Necessary versus sufficient conditions for exact solubility of statistical models on lattices'' [J. Math. Phys. 27, 593 (1986)

    NASA Astrophysics Data System (ADS)

    Gutkin, Eugene

    1987-05-01

    Lochak and Maillard [J. Math. Phys. 27, 593 (1986)] claim that the Baxter condition, which was known to be sufficient for the commutativity of transfer matrices, is also necessary (under some additional technical assumptions). Although the claim is correct, the proof in that paper is false. In this paper the errors of Lochak and Maillard are pointed out and correct proofs are outlined.

  11. Comment on 'Wave functions for a Duffin-Kemmer-Petiau particle in a time-dependent potential' [J. Math. Phys. 48, 073515 (2007)

    SciTech Connect

    Castro, L. B.; Castro, A. S. de

    2010-03-15

    It is shown that the paper 'Wave functions for a Duffin-Kemmer-Petiau particle in a time-dependent potential' by Merad and Bensaid [J. Math. Phys. 48, 073515 (2007)] is not correct in using inadvertently a non-Hermitian Hamiltonian in a formalism that does require Hermitian Hamiltonians.

  12. Comment on ``Note on the relation between thermophoresis and slow uniform flow problems for a rarefied gas'' [Phys. Fluids 21, 112001 (2009)

    NASA Astrophysics Data System (ADS)

    Sharipov, Felix

    2010-04-01

    This comment responds to the unjustified criticisms by Takata [Phys. Fluids 21, 112001 (2009)] to papers by Sharipov on the Onsager-Casimir reciprocal relations. It is shown that such relations obtained by Sharipov [Physica A 203, 437 (1994)], where the thermophoresis problem is not considered, are correct in the frame of assumptions made in the paper.

  13. Comment on ``Elastic wave propagation in a solid layer with laser-induced point defects'' [J. Appl. Phys. 110, 064906 (2011)

    NASA Astrophysics Data System (ADS)

    Martin, P. A.

    2012-09-01

    Mirzade [J. Appl. Phys. 110, 064906 (2011)] developed a linear theory for the propagation of waves in an elastic solid with atomic point defects, and then sought time-harmonic solutions. It is shown that Mirzade's analysis is incomplete: substantial corrections are required.

  14. Response to ``Comment on `Scaling of asymmetric magnetic reconnection: General theory and collisional simulations' '' [Phys. Plasmas 16, 034701 (2009)

    NASA Astrophysics Data System (ADS)

    Cassak, P. A.; Shay, M. A.

    2009-03-01

    The comment by Semenov et al. has called into question our derivation of the outflow velocity in asymmetric magnetic reconnection. We present three reasons that the analysis presented in the comment is incorrect. Most importantly, the authors of the comment have incorrectly applied results from one-dimensional shock theory to the problem of conservation through a two-dimensional dissipation region. For completeness, we compare their predictions to numerical simulation results, finding that their theory does not describe the data. We conclude the analysis in the comment is without merit.

  15. Al Composites

    NASA Astrophysics Data System (ADS)

    Chandanayaka, Tharaka; Azarmi, Fardad

    2014-05-01

    In the present study, cold spraying technique was used to fabricate a metal matrix composite (MMC) that consists of Ni matrix and 20 vol.% Ni3Al particles at two different particle sizes as reinforcement. This study intends to investigate the effect of reinforcement particle size on microstructural and mechanical properties of cold sprayed MMCs. Two different Ni3Al powders with nominal particle size of -45 to +5 and +45 to 100 μm were used as reinforcement in this study. Cold sprayed Ni-Ni3Al samples were subjected to the microstructural observation and characterization prior to any mechanical testing. Then, samples were tested using nano-indentation, Knoop hardness, Vickers hardness, and Resonance frequency to evaluate their mechanical properties. No significant changes were observed in microstructural characteristics due to different particle sizes. The results obtained from a variety of mechanical testings indicated that the increasing reinforcement particle size resulted in the slight reduction of mechanical properties such as elastic modulus and hardness in cold sprayed MMCs. The mechanical interlock between deposited particles defines the bonding strength in cold sprayed samples. Small size particles have a higher velocity and impact resulting in stronger interlock between deformed particles.

  16. Comment on “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation” [Phys. Fluids 26, 065105 (2014)

    SciTech Connect

    Hietala, Niklas Hänninen, Risto

    2014-11-15

    Van Gorder considers a formulation of the local induction approximation, which allows the vortex to move in the direction of the reference axis [“General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014)]. However, in his analytical and numerical study he does not use it. A mistake in the torsion of a helical vortex is also corrected.

  17. Response to “Comment on ‘Stationary self-focusing of Gaussian laser beam in relativistic thermal quantum plasma’” [Phys. Plasmas 21, 064701 (2014)

    SciTech Connect

    Patil, S. D.; Takale, M. V.

    2014-06-15

    Habibi and Ghamari have presented a Comment on our paper [Phys. Plasmas 20, 072703 (2013)] by examining quantum dielectric response in thermal quantum plasma. They have modeled the relativistic self-focusing of Gaussian laser beam in cold and warm quantum plasmas and reported that self-focusing length does not change in both situations. In this response, we have reached the following important conclusions about the comment itself.

  18. 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

  19. Response to 'Comment on 'Three-dimensional numerical investigation of electron transport with rotating spoke in a cylindrical anode layer Hall plasma accelerator''[Phys. Plasmas 20, 014701 (2013)

    SciTech Connect

    Tang, D. L.; Qiu, X. M.; Geng, S. F.; Chu, Paul K.

    2013-01-15

    The numerical simulation described in our paper [D. L. Tang et al., Phys. Plasmas 19, 073519 (2012)] shows a rotating dense plasma structure, which is the critical characteristic of the rotating spoke. The simulated rotating spoke has a frequency of 12.5 MHz with a rotational speed of {approx}1.0 Multiplication-Sign 10{sup 6} m/s on the surface of the anode. Accompanied by the almost uniform azimuthal ion distribution, the non-axisymmetric electron distribution introduces two azimuthal electric fields with opposite directions. The azimuthal electric fields have the same rotational frequency and speed together with the rotating spoke. The azimuthal electric fields excite the axial electron drift upstream and downstream due to the additional E{sub {theta}} x B field and then the axial shear flow is generated. The axial local charge separation induced by the axial shear electron flow may be compensated by the azimuthal electron transport, finally resulting in the azimuthal electric field rotation and electron transport with the rotating spoke.

  20. Comment on “Magnetic field mediated low-temperature resistivity upturn in electron-doped La{sub 1−x}Hf{sub x}MnO{sub 3} manganite oxides” [J. Appl. Phys. 112, 123710 (2012)

    SciTech Connect

    Rozenberg, E.

    2014-01-21

    In a recent paper, Guo et al. [J. Appl. Phys. 112, 123710 (2012)] reported on characteristic features of the temperature (T) and magnetic field (H) dependences of electrical resistivity (ρ) in polycrystalline La{sub 1−x}Hf{sub x}MnO{sub 3} (x = 0.2 and 0.3) manganites. In particular, shallow minima were observed at some T{sub min} below 100 K on ρ(T) curves. Application of an external H ≤ 5 T leads first to a decrease in the T{sub min} value, while this value increases notably at H > 0.75 T. The authors attributed this complex behavior to competitive electron-electron interaction and Kondo-like spin dependent scattering of carriers. It is shown in the comment that such interpretation is very questionable due to the fundamental inapplicability of this approach for analysis of low-T conductivity in polycrystalline manganites. It seems that the most likely reason for the appearance of the low temperature minima on ρ(T) curves and their evolution upon field application is the well known grain boundary effects in magnetically and structurally inhomogeneous samples.

  1. Comment on “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” [Phys. Plasmas 20, 033106 (2013)

    SciTech Connect

    Petrillo, V.; Rossi, A. R.; Serafini, L.

    2013-12-15

    We point out that in the equation for the electron distribution evolution during Thomson/Compton or undulator radiation used in the paper: “Competition between coherent emission and broadband spontaneous emission in the quantum free electron laser” by G. R. M. Robb and R. Bonifacio [Phys. Plasmas 20, 033106 (2013)], the weight function should be the distribution of the number of emitted photons and not the photon energy distribution. Nevertheless, the considerations expressed in this comment do not alter the conclusions drawn in the paper in object.

  2. Comment on "Propagation of a TE surface mode in a relativistic electron beam-quantum plasma system" [Phys. Lett. A 376 (2012) 169

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2016-07-01

    In a recent paper Abdel Aziz [Phys. Lett. A 376 (2012) 169] obtained the dispersion properties of TE surface modes propagating at the interface between a magnetized quantum plasma and vacuum in the Faraday configuration, where these TE surface waves are excited during the interaction of relativistic electron beam with magnetized quantum plasma. The present Comment points out that in the Faraday configuration the surface waves acquire both TM and TE components due to the cyclotron motion of electrons. Therefore, the TE surface waves cannot propagate on surface of the present system and the general dispersion relations for surface waves, derived by Abdel Aziz are incorrect.

  3. Muon sites in Ce(Ru,Rh)2Al10 investigated by using Density Functional Theory from the view point of electronic potential

    NASA Astrophysics Data System (ADS)

    Adam, N.; Suprayoga, E.; Adiperdana, B.; Guo, H.; Tanida, H.; Mohd-Tajudin, S. S.; Kobayashi, R.; Sera, M.; Nishioka, T.; Matsumura, M.; Sulaiman, S.; Mohamed-Ibrahim, M. I.; Watanabe, I.

    2014-12-01

    Numerical investigations on muon sites in Ce-based Kondo semiconductors, Ce(Ru,Rh)2Al10 were carried out by using the Density Functional Theory. From the view point of simple electrostatic potential calculations, we found all the previously reported muon sites, suggested by different groups (Kambe S et al. 2010 J. Phys. Soc. Jpn. 79 053708 and Khalyavin D D et al., 2010 Phys. Rev. B 82 100405(R)), can be possibly chosen as muon stopping sites. We also investigated the changes in the potential of the Rh-doped case. We discovered that the electronic potential around the nearest Ru atom to the substituted Rh atom is affected and the potential becomes asymmetric around the nearest Ru ion. Although big changes in hyperfine fields at muon sites have been reported (Guo H et al. 2013 Phys. Rev. B 88 115206), the muon positions estimated from the potential calculations do not change much.

  4. 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).

  5. Pure AlN layers in metal-polar AlGaN/AlN/GaN and AlN/GaN heterostructures grown by low-temperature ammonia-based molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Kaun, Stephen W.; Mazumder, Baishakhi; Fireman, Micha N.; Kyle, Erin C. H.; Mishra, Umesh K.; Speck, James S.

    2015-05-01

    When grown at a high temperature (820 °C) by ammonia-based molecular beam epitaxy (NH3-MBE), the AlN layers of metal-polar AlGaN/AlN/GaN heterostructures had a high GaN mole fraction (∼0.15), as identified by atom probe tomography in a previous study (Mazumder et al 2013 Appl. Phys. Lett. 102 111603). In the study presented here, growth at low temperature (<740 °C) by NH3-MBE yielded metal-polar AlN layers that were essentially pure at the alloy level. The improved purity of the AlN layers grown at low temperature was correlated to a dramatic increase in the sheet density of the two-dimensional electron gas (2DEG) at the AlN/GaN heterointerface. Through application of an In surfactant, metal-polar AlN(3.5 nm)/GaN and AlGaN/AlN(2.5 nm)/GaN heterostructures grown at low temperature yielded low 2DEG sheet resistances of 177 and 285 Ω/□, respectively.

  6. Comment on 'Continuum modes in rotating plasmas: General equations and continuous spectra for large aspect ratio tokamaks'[Phys. Plasmas 18, 092103 (2011)

    SciTech Connect

    Goedbloed, J. P.

    2012-06-15

    It is shown that some of the main results of the recent paper by Lakhin and Ilgisonis [Phys. Plasmas 18, 092103 (2011)], viz. the derivation of the equations for the continuous spectra of poloidally and toroidally rotating plasmas and their special solution for large aspect ratio tokamaks with large parallel flows were obtained before by Goedbloed, Belieen, van der Holst, and Keppens [Phys. Plasmas 11, 28 (2004)]. A further rearrangement of the system of equations for the coupled Alfven and slow continuous spectra clearly exhibits: (a) coupling through a single tangential derivative, which is a generalization of the geodesic curvature; (b) the 'transonic' transitions of the equilibrium, which need to be carefully examined in order to avoid entering hyperbolic flow regimes where the stability formalism breaks down. A critical discussion is devoted to the implications of this failure, which is generally missed in the tokamak literature, possibly as a result of the wide-spread use of the sonic Mach number of gas dynamics, which is an irrelevant and misleading parameter in 'transonic' magnetohydrodynamics. Once this obstacle in understanding is removed, further application of the theory of trans-slow Alfven continuum instabilities to both tokamaks, with possible implications for the L-H transition, and astrophysical objects like 'fat' accretion disks, with a possible new route to magnetohydrodynamic turbulence, becomes feasible.

  7. Stripe-teeth metamaterial Al- and Nb-based rectennas (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Osgood, Richard M.; Giardini, Stephen A.; Carlson, Joel B.; Joghee, Prabhuram; O'Hayre, Ryan P.; Diest, Kenneth; Rothschild, Mordechai

    2015-09-01

    Unlike a semiconductor, where the absorption is limited by the band gap, a "microrectenna array" could theoretically very efficiently rectify any desired portion of the infrared frequency spectrum (25 - 400 THz). We investigated vertical metal-insulator-metal (MIM) diodes that rectify vertical high-frequency fields produced by a metamaterial planar stripe-teeth Al or Au array (above the diodes), similar to stripe arrays that have demonstrated near-perfect absorption in the infrared due to critical coupling [1]. Using our design rules that maximize asymmetry (and therefore the component of the electric field pointed into the substrate, analogous to Second Harmonic Generation), we designed, fabricated, and analyzed these metamaterial-based microrectenna arrays. NbOx and Al2O3 were produced by anodization and ALD, respectively. Smaller visible-light Pt-NbOx-Nb rectennas have produced output power when illuminated by visible (514 nm) light [2]. The resonances of these new Au/NbOx/Nb and Al/Al2O3/Al microrectenna arrays, with larger dimensions and more complex nanostructures than in Ref. 1, were characterized by microscopic FTIR microscopy and agreed well with FDTD models, once the experimental refractive index values were entered into the model. Current-voltage measurements were carried out, showed that the Al/Al2O3/Al diodes have very large barrier heights and breakdown voltages, and were compared to our model of the MIM diode. We calculate expected THz-rectification using classical [3] and quantum [4] rectification models, and compare to measurements of direct current output, under infrared illumination. [1] C. Wu, et. al., Phys. Rev. B 84 (2011) 075102. [2] R. M. Osgood III, et. al., Proc. SPIE 8096, 809610 (2011). [3] A. Sanchez, et. al., J. Appl. Phys. 49 (1978) 5270. [4] J. R. Tucker and M. J. Feldman, Rev. of Mod. Phys. 57, (1985)1055.

  8. GW calculations of band offsets at AlN/GaN interfaces.

    NASA Astrophysics Data System (ADS)

    Cociorva, Daniel; Wilkins, John W.

    1998-03-01

    We study the quasiparticle bands at the interface of AlN and GaN using the GW approximation for the electron self-energy. Two structures are studied: the zinc-blende (cubic) interface in the (111) direction and the wurtzite (hexagonal) interface in the (001) direction. Our short superlattices are consistent with 4×4 LDA work(F. Bernardini et al.), Materials Research Society symposia proceedings 449, 923 (1997). and ``1×2'' GW work.(A. Rubio et al.), Phys. Rev. B 49, 1952 (1994). For comparison with recent experiments we are implementing a scalable parallel algorithm based on the reciprocal space formulation(M. S. Hybertsen and S. G. Louie, Phys. Rev. Lett. 55), 1418 (1985). to determine the self energy for thicker superlattices.

  9. 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.

  10. Comment on “Rethinking first-principles electron transport theories with projection operators: The problems caused by partitioning the basis set” [J. Chem. Phys. 139, 114104 (2013)

    SciTech Connect

    Brandbyge, Mads

    2014-05-07

    In a recent paper Reuter and Harrison [J. Chem. Phys. 139, 114104 (2013)] question the widely used mean-field electron transport theories, which employ nonorthogonal localized basis sets. They claim these can violate an “implicit decoupling assumption,” leading to wrong results for the current, different from what would be obtained by using an orthogonal basis, and dividing surfaces defined in real-space. We argue that this assumption is not required to be fulfilled to get exact results. We show how the current/transmission calculated by the standard Greens function method is independent of whether or not the chosen basis set is nonorthogonal, and that the current for a given basis set is consistent with divisions in real space. The ambiguity known from charge population analysis for nonorthogonal bases does not carry over to calculations of charge flux.

  11. Breaking with Traditional Phys Ed.

    ERIC Educational Resources Information Center

    Siegel, Dorothy

    1978-01-01

    Project ACTIVE (All Children Totally Involved Exercising) is an individualized physical education program which started in Oakhurst, New Jersey, and has spread nationally. An exercise program is tailored to each participant's personal needs, determined by medical examination and fitness tests. Nutrition instruction may be combined with the…

  12. Energetic ion bombarded Fe/Al multilayers

    SciTech Connect

    Al-Busaidy, M.S.; Crapper, M.D.

    2006-05-15

    The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

  13. Entropic uncertainty and measurement reversibility

    NASA Astrophysics Data System (ADS)

    Berta, Mario; Wehner, Stephanie; Wilde, Mark M.

    2016-07-01

    The entropic uncertainty relation with quantum side information (EUR-QSI) from (Berta et al 2010 Nat. Phys. 6 659) is a unifying principle relating two distinctive features of quantum mechanics: quantum uncertainty due to measurement incompatibility, and entanglement. In these relations, quantum uncertainty takes the form of preparation uncertainty where one of two incompatible measurements is applied. In particular, the ‘uncertainty witness’ lower bound in the EUR-QSI is not a function of a post-measurement state. An insightful proof of the EUR-QSI from (Coles et al 2012 Phys. Rev. Lett. 108 210405) makes use of a fundamental mathematical consequence of the postulates of quantum mechanics known as the non-increase of quantum relative entropy under quantum channels. Here, we exploit this perspective to establish a tightening of the EUR-QSI which adds a new state-dependent term in the lower bound, related to how well one can reverse the action of a quantum measurement. As such, this new term is a direct function of the post-measurement state and can be thought of as quantifying how much disturbance a given measurement causes. Our result thus quantitatively unifies this feature of quantum mechanics with the others mentioned above. We have experimentally tested our theoretical predictions on the IBM quantum experience and find reasonable agreement between our predictions and experimental outcomes.

  14. Comment on "Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake" [Phys. Plasmas 20, 102507 (2013)

    NASA Astrophysics Data System (ADS)

    Ryutov, D. D.; Cohen, R. H.; Rognlien, T. D.; Soukhanovskii, V. A.; Umansky, M. V.

    2014-05-01

    In the recently published paper "Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake" [Phys. Plasmas 20, 102507 (2013)], the authors raise interesting and important issues concerning divertor physics and design. However, the paper contains significant errors: (a) The conceptual framework used in it for the evaluation of divertor "quality" is reduced to the assessment of the magnetic field structure in the outer Scrape-Off Layer. This framework is incorrect because processes affecting the pedestal, the private flux region and all of the divertor legs (four, in the case of a snowflake) are an inseparable part of divertor operation. (b) The concept of the divertor index focuses on only one feature of the magnetic field structure and can be quite misleading when applied to divertor design. (c) The suggestion to rename the divertor configurations experimentally realized on NSTX (National Spherical Torus Experiment) and DIII-D (Doublet III-D) from snowflakes to X-divertors is not justified: it is not based on comparison of these configurations with the prototypical X-divertor, and it ignores the fact that the NSTX and DIII-D poloidal magnetic field geometries fit very well into the snowflake "two-null" prescription.

  15. Comment on “Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake” [Phys. Plasmas 20, 102507 (2013)

    SciTech Connect

    Ryutov, D. D. Cohen, R. H.; Rognlien, T. D.; Soukhanovskii, V. A.; Umansky, M. V.

    2014-05-15

    In the recently published paper “Magnetic geometry and physics of advanced divertors: The X-divertor and the snowflake” [Phys. Plasmas 20, 102507 (2013)], the authors raise interesting and important issues concerning divertor physics and design. However, the paper contains significant errors: (a) The conceptual framework used in it for the evaluation of divertor “quality” is reduced to the assessment of the magnetic field structure in the outer Scrape-Off Layer. This framework is incorrect because processes affecting the pedestal, the private flux region and all of the divertor legs (four, in the case of a snowflake) are an inseparable part of divertor operation. (b) The concept of the divertor index focuses on only one feature of the magnetic field structure and can be quite misleading when applied to divertor design. (c) The suggestion to rename the divertor configurations experimentally realized on NSTX (National Spherical Torus Experiment) and DIII-D (Doublet III-D) from snowflakes to X-divertors is not justified: it is not based on comparison of these configurations with the prototypical X-divertor, and it ignores the fact that the NSTX and DIII-D poloidal magnetic field geometries fit very well into the snowflake “two-null” prescription.

  16. Comment on "Application of the extended Lie group analysis to the Hopf functional formulation of the Burgers equation" [J. Math. Phys. 54, 072901 (2013)

    NASA Astrophysics Data System (ADS)

    Frewer, Michael; Khujadze, George; Foysi, Holger

    2016-03-01

    The quest to find new statistical symmetries in the theory of turbulence is an ongoing research endeavor which is still in its beginning and exploratory stage. In our comment we show that the recently performed study of Wacławczyk and Oberlack [J. Math. Phys. 54, 072901 (2013)] failed to present such new statistical symmetries. Despite their existence within a functional Fourier space of the statistical Burgers equation, they all can be reduced to the classical and well-known symmetries of the underlying deterministic Burgers equation itself, except for one symmetry, but which, as we will demonstrate, is only a mathematical artefact without any physical meaning. Moreover, we show that the proposed connection between the translation invariance of the multi-point moments and a symmetry transformation associated to a certain invariant solution of the inviscid functional Burgers equation is invalid. In general, their study constructs and discusses new particular solutions of the functional Burgers equation without referring them to the well-established general solution. Finally, we also see a shortcoming in the presented methodology as being too restricted to construct a complete set of Lie point symmetries for functional equations. In particular, for the considered Burgers equation essential symmetries are not captured.

  17. Comment on "A model for phosphate glass topology considering the modifying ion sub-network" [J. Chem. Phys. 140, 154501 (2014)

    NASA Astrophysics Data System (ADS)

    Sidebottom, David L.

    2015-03-01

    In a recent paper, Hermansen, Mauro, and Yue [J. Chem. Phys. 140, 154501 (2014)] applied the temperature-dependent constraint theory to model both the glass transition temperature, Tg, and fragility, m, of a series of binary alkali phosphate glasses of the form (R2O)x (P2 O 5) 1 - x , where R represents an alkali species. Key to their success seems to be the retention of linear constraints between the alkali ion (R+) and the non-bridging oxygens near Tg, which allows the model to mimic a supposed minimum for both Tg(x) and m(x) located near x = 0.2. However, the authors have overlooked several recent studies that clearly show there is no minimum in m(x). We argue that the retention of the alkali ion constraints at these temperatures is unjustified and question whether the model calculations can be revised to meet the actual experimental data. We also discuss alternative interpretations for the fragility based on two-state thermodynamics that can accurately account for its compositional dependence.

  18. Comment on “A model for phosphate glass topology considering the modifying ion sub-network” [J. Chem. Phys. 140, 154501 (2014)

    SciTech Connect

    Sidebottom, David L.

    2015-03-14

    In a recent paper, Hermansen, Mauro, and Yue [J. Chem. Phys. 140, 154501 (2014)] applied the temperature-dependent constraint theory to model both the glass transition temperature, T{sub g}, and fragility, m, of a series of binary alkali phosphate glasses of the form (R{sub 2}O){sub x}(P{sub 2}O{sub 5}){sub 1−x}, where R represents an alkali species. Key to their success seems to be the retention of linear constraints between the alkali ion (R{sup +}) and the non-bridging oxygens near T{sub g}, which allows the model to mimic a supposed minimum for both T{sub g}(x) and m(x) located near x = 0.2. However, the authors have overlooked several recent studies that clearly show there is no minimum in m(x). We argue that the retention of the alkali ion constraints at these temperatures is unjustified and question whether the model calculations can be revised to meet the actual experimental data. We also discuss alternative interpretations for the fragility based on two-state thermodynamics that can accurately account for its compositional dependence.

  19. Phase equilibrium and structural properties in the Ca-Al-Si-O system up to the P,T conditions of the Earth's lowermost transition zone.

    NASA Astrophysics Data System (ADS)

    Gréaux, S.; Nishiyama, N.; Kono, Y.; Shinmei, T.; Irifune, T.

    2008-12-01

    Ca- and Al-bearing silicates have been extensively investigated for their importance into the mantle processes. In the transition zone, majorite garnet and Ca-perovskite are reported to be the major hosts of Ca as well as deposits of Al [1]. At higher P, Ca gets completely exsolved from the majorite to the Ca-pv. It is observed that Al plays a significant role in the Ca-Si-O system by inducing new phase equilibriums [2,3,4], and influencing the physical properties of the Ca-pv [5]. It is then suggested that phase transitions and chemical reactions involving Ca- and Al-bearing silicates could conciliate mineralogical results and seismological observations in the region of the transition zone [3,6]. We studied the phase equilibrium at HP-HT in the grossular and anorthite systems using a Kawai-type multi- anvil apparatus up to 25 GPa and 2000 K. Grossular garnet is reported to decompose into a mix of corundum and Ca-pv [3] or to transform into a perovskite of grossular composition [7]. Our study shows that grossular mainly decomposes into a mix of Al-Ca-pv and CAS phase in the same P range and higher T. Anorthite is also found to mainly decompose into a mix of Al-Ca-pv and CAS phase. Despite some Al-content in the Ca-pv, the CAS phase is the major host of Al, which suggests according to previous studies [3,5], a lower solubility of Al into the perovskite structure at high T. The Al-content of the Ca-pv as well as the presence of another Al-rich Ca-bearing silicate in zone of variable temperatures and composition as subducting slabs are discussed for their possible implication into the transition zone processes. [1] T. Irifune, 1994. Nature 370, 131-133 [2] L. Gautron et al., 1996. Phys. Earth Planet. Int. 94, 71-81 [3] N. Takafuji et al., 2002. Phys. Chem. Mineral 29, 532-537 [4] S. Zhai and E. Ito, 2008. Phys. Earth Planet. Int. In press [5] T. Kurashina et al., 2004. Phys. Earth Planet. Int. 145, 67-7 [6] L. Stixrude et al., 1996. Am. Mineral. 81, 1293-1296 [7] H

  20. Comment on “Structural, dielectric, optical and ferroelectric property of urea succinic acid crystals grown in aqueous solution containing maleic acid” by B.K. Singh et al. [J. Phys. Chem. Solids 71 (2010) 1774

    NASA Astrophysics Data System (ADS)

    Tylczyński, Zbigniew

    2012-07-01

    The volume of elementary cell of the urea succinic acid (M-USA) growing from a solution containing 1 mol% maleic acid is 69% greater than that of urea succinic acid (USA) grown in the usual conditions. M-USA crystallises in the monoclinic system with a centre of symmetry, which excludes the piezoelectric and ferroelectric properties. The results presented in the paper commented on are artefacts.

  1. Electrodynamic force law controversy.

    PubMed

    Graneau, P; Graneau, N

    2001-05-01

    Cavalleri et al. [Phys. Rev. E 52, 2505 (1998); Eur. J. Phys. 17, 205 (1996)] have attempted to resolve the electrodynamic force law controversy. This attempt to prove the validity of either the Ampère or Lorentz force law by theory and experiment has revealed only that the two are equivalent when predicting the force on part of a circuit due to the current in the complete circuit. However, in our analysis of internal stresses, only Ampère's force law agrees with experiment. PMID:11415053

  2. Response to {open_quotes}Comment on {open_quote}Reversible work of formation of an embryo of a new phase within a uniform macroscopic mother phase{close_quote}thinsp{close_quotes} [J. Chem. Phys. {bold 111}, 3769 (1999)

    SciTech Connect

    Debenedetti, P.G.; Reiss, H.

    1999-08-01

    External constraints are necessary in order to calculate the energetics of embryo formation when the embryo is not a critical nucleus. The expression for the reversible work of formation obtained in by Debenedetti and Reiss [J. Chem. Phys. {bold 108}, 5498 (1998)] is rigorous and valid regardless of the relative densities of the embryo and mother phase. {copyright} {ital 1999 American Institute of Physics.}

  3. Comment on "Is the regulation of the electronic properties of organic molecules by polynuclear superhalogens more effective than that by mononuclear superhalogens? A high-level ab initio case study" by M.-M. Li, J.-F. Li, H.-C. Bai, Y.-Y. Sun, J.-L. Li and B. Yin, Phys. Chem. Chem. Phys., 2015, 17, 20338.

    PubMed

    Díaz-Tinoco, Manuel; Ortiz, J V

    2016-06-01

    The Outer Valence Green Function (OVGF) and coupled-cluster singles and doubles plus approximate triples, or CCSD(T), methods yield similar results for the vertical detachment energies of superhalides studied recently by Li et al. The success of the OVGF method contradicts claims by Li et al. in their recent article. PMID:27194225

  4. The fragility of Al Ni-based glass-forming melts

    NASA Astrophysics Data System (ADS)

    Si, Pengchao; Bian, Xiufang; Zhang, Junyan; Li, Hui; Sun, Minhua; Zhao, Yan

    2003-08-01

    In the original description of fragility, Angell (1988 J. Phys. Chem. Solids 49 863) determined the degree of fragility from the curvature on an Arrhenius plot. This paper discusses a new measurement of the fragility value. The fragility of Al-Ni-based glass-forming melts, which is seldom reported in this field, can be analysed by using data from their viscosity and thermal properties. The fragility is observed to be very high, which is in very good agreement with the low glass-forming ability of Al-Ni-based alloys.

  5. Impact of Duality Violations on Spectral Sum Rule analyses

    NASA Astrophysics Data System (ADS)

    Catà, Oscar

    2007-02-01

    Recent sum rule analyses on the two-point correlator have led to significant discrepancies in the values found for the OPE condensates, most dramatically in the dimension eight condensate and to a lesser extent in the dimension six one [R. Barate et al., ALEPH Collaboration, Eur. Phys. J. C 4 (1998) 409; K. Ackerstaff et al., OPAL Collaboration, Eur. Phys. J. C 7 (1999) 571, arXiv:hep-ex/9808019; S. Peris, B. Phily and E. de Rafael, Phys. Rev. Lett. 86 (2001) 14, arXiv:hep-ph/0007338; S. Friot, D. Greynat and E. de Rafael, JHEP 0410 (2004) 043, arXiv:hep-ph/0408281; M. Davier, L. Girlanda, A. Hocker and J. Stern, Phys. Rev. D 58 (1998) 096014, arXiv:hep-ph/9802447; B.L. Ioffe and K.N. Zyablyuk, Nucl. Phys. A 687 (2001) 437, arXiv:hep-ph/0010089. K.N. Zyablyuk, Eur. Phys. J. C 38 (2004) 215, arXiv:hep-ph/0404230; J. Bijnens, E. Gamiz and J. Prades, JHEP 0110 (2001) 009, arXiv:hep-ph/0108240; C.A. Dominguez and K. Schilcher, Phys. Lett. B 581 (2004) 193, arXiv:hep-ph/0309285; J. Rojo and J. I. Latorre, JHEP 0401 (2004) 055, arXiv:hep-ph/0401047; V. Cirigliano, E. Golowich and K. Maltman, Phys. Rev. D 68 (2003) 054013, arXiv:hep-ph/0305118; S. Ciulli, C. Sebu, K. Schilcher and H. Spiesberger, Phys. Lett. B 595 (2004) 359, arXiv:hep-ph/0312212. S. Narison, arXiv:hep-ph/0412152]. Precise knowledge of these condensates is of relevance in kaon decays [M. Knecht, S. Peris and E. de Rafael, Phys. Lett. B 457 (1999) 227, arXiv:hep-ph/9812471; J.F. Donoghue and E. Golowich, Phys. Lett. B 478 (2000) 172, arXiv:hep-ph/9911309; M. Knecht, S. Peris and E. de Rafael, Phys. Lett. B 508 (2001) 117, arXiv:hep-ph/0102017] and therefore it seems mandatory to assess the actual impact of what is commonly neglected in spectral sum rules, most prominently the issue of duality violations. We will explicitly compute them in a toy model and show that they are a priori non-negligible.

  6. Determination of the thermophysical properties of evolutive porous media: application to Civil Engineering materials

    NASA Astrophysics Data System (ADS)

    Poullain, P.; Mounanga, P.; Bastian, G.; Coué, R.

    2006-01-01

    The purpose of this paper is to describe the development and the use of two measurement techniques especially adapted to the rapid determination of the thermophysical properties of evolutive porous media. The first technique exploits the method of the “heated and non-heated wires” and is validated on wet clay by comparison with previous works [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004)]. It is then used to quantify the evolution of both thermal conductivity and volumetric heat capacity of hardening cement pastes maintained at 294 ± 1 K. The second technique is based on the classical method of the “heating film” and a data treatment using forward calculation. This technique is first used to measure the properties of well-known materials (hardened mortars, wet sand [Mounanga et al., Eur. Phys. J. Appl. Phys. 26, 65 (2004); Delacre, Ph.D. thesis, University of Artois, 2000] and glass [Bastian, Rev. Phys. Appl. 22, 431 (1987)] and then applied to media whose properties evolve both over time and through space (drying sand).

  7. Comment on “Comparative study of beta-decay data for eight nuclides measured at the Physikalisch-Technische Bundesanstalt” [Astropart. Phys. 59 (2014) 47-58

    NASA Astrophysics Data System (ADS)

    Nähle, Ole; Kossert, Karsten

    2015-06-01

    We would like to comment on a recent paper by Sturrock et al. (2014) in which the authors analyze decay data acquired by an ionization chamber in our institute. They interpret the variations in the data as solar-driven changes in the decay rates of the radionuclides under study. In brief we would like to discuss and elucidate the properties and the origin of the data used by the authors and explain why these data are not a sound basis for claiming evidence for new physics.

  8. ALS - The cost cutter

    NASA Astrophysics Data System (ADS)

    Colucci, Frank

    1987-10-01

    The Advanced Launch System (ALS) development program will avail itself of existing technologies in the short term in order to produce an interim 'core' vehicle that may be operational by 1993; the full, booster-incorporating system objective will then be achieved in 1998. This programmatic 'decoupling' of booster and core vehicle development efforts will separate their funding peaks. The ALS program will cut costs by colocating manufacturing and launch facilities, using Al-Li alloys in booster primary structures, and aggressively applying 'paperless' CIM. The ALS launch vehicle configuration will be primarily determined by both payload requirements and flight frequency.

  9. Kinetic water-bag model of global collisional drift waves and ion temperature gradient instabilities in cylindrical geometry

    SciTech Connect

    Gravier, E.; Plaut, E.

    2013-04-15

    Collisional drift waves and ion temperature gradient (ITG) instabilities are studied using a linear water-bag kinetic model [P. Morel et al., Phys. Plasmas 14, 112109 (2007)]. An efficient spectral method, already validated in the case of drift waves instabilities [E. Gravier et al., Eur. Phys. J. D 67, 7 (2013)], allows a fast solving of the global linear problem in cylindrical geometry. The comparison between the linear ITG instability properties thus computed and the ones given by the COLUMBIA experiment [R. G. Greaves et al., Plasma Phys. Controlled Fusion 34, 1253 (1992)] shows a qualitative agreement. Moreover, the transition between collisional drift waves and ITG instabilities is studied theoretically as a function of the ion temperature profile.

  10. Generalized Kolbenstvedt model for electron impact ionization of the K-, L- and M-shell ions

    NASA Astrophysics Data System (ADS)

    Haque, A. K. F.; Shahjahan, M.; Uddin, M. A.; Patoary, M. A. R.; Basak, A. K.; Saha, B. C.; Malik, F. B.

    2010-04-01

    The recently proposed generalized Kolbenstvedt model (GKLV) of Haque et al (2007 Eur. Phys. J. D 42 203), for the electron impact ionization (EII) of atoms, was applied to a wide range of K-, L- and M-shell electrons of ionic targets from threshold to 1 MeV incident energy. The set of species-independent parameters, two for each of the ionized orbits, is the same as that for neutral targets, and provides an excellent account of the EII cross-sectional data for 36 ions, including those belonging to Li, Be, B, C, N, O and Ne electronic sequences as well as those having 3s-, 3p- and 3d-configurations of the M-shell in a consistent manner. The performance of GKLV is found to be better than that of the modified version of the BELL model (Haque et al 2006 Phys. Rev. A 73 052703, Haque et al 2006 Phys. Scr. 74 377).

  11. Alternative Tsunami Models

    ERIC Educational Resources Information Center

    Tan, A.; Lyatskaya, I.

    2009-01-01

    The interesting papers by Margaritondo (2005 "Eur. J. Phys." 26 401) and by Helene and Yamashita (2006 "Eur. J. Phys." 27 855) analysed the great Indian Ocean tsunami of 2004 using a simple one-dimensional canal wave model, which was appropriate for undergraduate students in physics and related fields of discipline. In this paper, two additional,…

  12. Comment on “A study of vertical and in-plane electron mobility due to interface roughness scattering at low temperature in InAs-GaSb superlattices” [J. Appl. Phys. 114, 053712 (2013)

    SciTech Connect

    Szmulowicz, F.

    2014-04-14

    The purpose of this comment is to point out that the paper by Safa, Asgari, and Faraone [J. Appl. Phys. 114, 053712 (2013)] (SAF) on electronic transport in superlattices contains a number of errors in physics and execution. By dealing with a finite number of periods and forcing the wave function to be zero at the upper and lower boundaries of the superlattice stack, SAF have turned the system into a quantum well for which the momentum along the growth axis is not a good quantum number, so that the bands in the growth direction are flat and the corresponding carrier velocities and vertical mobilities are zero. A number of other errors allow the authors to get nonzero results and to reach conclusions that qualitatively mirror those of Szmulowicz, Haugan, Elhamri, and Brown [Phys. Rev. B 84, 155307 (2011)].

  13. Translationally Invariant Calculations of Form Factors, Densities and Momentum Distributions for Finite Nuclei with Short-Range Correlations Included: A Fresh Look

    NASA Astrophysics Data System (ADS)

    Shebeko, A.; Grigorov, P.; Iurasov, V.

    2014-08-01

    The approach proposed in the 70s (Dementiji et al. in Sov J Nucl Phys 22:6-9, 1976), when describing the elastic and inelastic electron scattering off 4 He, and elaborated in (Shebeko et al.in Eur Phys J A27:143-155, 2006) for calculations of the one-body, two-body and more complex density matrices of finite bound systems has been applied (Shebeko and Grigorov in Ukr J Phys 52:830-842, 2007; Shebeko et al. in Eur. Phys. J. A48:153-172, 2012) in studying a combined effect of the center-of-mass motion and nucleon-nucleon short-range correlations on the nucleon density and momentum distributions in light nuclei beyond the independent particle model. Unlike a common practice, suitable for infinite bound systems, these distributions are determined as expectation values of appropriate intrinsic operators that depend upon the relative coordinates and momenta (Jacobi variables) and act on the intrinsic ground-state wave functions (WFs). The latter are constructed in the so-called fixed center-of-mass approximation, starting with a mean-field Slater determinant modified by some correlator (e.g., after Jastrow or Villars). Our numerical calculations of the charge form factors ( F CH ( q)), densities and momentum distributions have been carried out for nuclei 4 He and 16 O choosing, respectively, the 1 s and 1 s-1 p Slater determinants of the harmonic oscillator model as trial, nontranslationally invariant WFs.

  14. Al-Anon/Alateen

    MedlinePlus

    Find an Al-Anon meeting Español | Français 2018 Int'l Convention Home About Group Meetings What If I'm not ready ... a meeting? What can I expect at an Al-Anon meeting? What was my first meeting like? ...

  15. Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)

    SciTech Connect

    Van Gorder, Robert A.

    2014-11-15

    In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it was clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.

  16. [Environmental factors in ALS].

    PubMed

    Juntas-Morales, Raul; Pageot, Nicolas; Corcia, Philippe; Camu, William

    2014-05-01

    ALS is likely to be a disorder of multifactorial origin. Among all the factors that may increase the risk of ALS, environmental ones are being studied for many years, but in the recent years, several advances have pointed to a new interest in their potential involvement in the disease process, especially for the cyanotoxin BMAA. Food containing BMAA has been found on Guam, a well-known focus of ALS/parkinsonism/dementia and high levels of BMAA have been identified into the brain of these patients. The BMAA cyanotoxin is potentially ubiquitous and have also been found into the food of patients who died from ALS both in Europe and USA. BMAA can be wrongly integrated into the protein structure during mRNA traduction, competing with serine. This may induce abnormal protein folding and a subsequent cell death. Heavy metals, such as lead or mercury may be directly toxic for neuronal cells. Several works have suggested an increased risk of ALS in individuals chronically exposed to these metals. Exposure to pesticides has been suggested to be linked to an increased risk of developing ALS. The mechanism of their toxicity is likely to be mediated by paraoxonases. These proteins are in charge of detoxifying the organism from toxins, and particularly organophosphates. To date, there are insufficient scientific data to suggest that exposure to electromagnetic fields may increase the risk of having ALS. We are particularly missing longitudinal cohorts to demonstrate that risk. PMID:24703731

  17. All About ALS

    MedlinePlus

    ... External link, please review our exit disclaimer . Subscribe All About ALS Understanding a Devastating Disorder In the ... a coffee pot, or button a shirt. Eventually, all muscles under voluntary control are affected, and people ...

  18. Amyotrophic Lateral Sclerosis (ALS)

    MedlinePlus

    ... Pictures of ALS Mutant Proteins Support Two Major Theories About How the Disease is Caused May 2003 ... All NINDS-prepared information is in the public domain and may be freely copied. Credit to the ...

  19. 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 ...

  20. ALS synchrotron radiation shielding

    SciTech Connect

    Donahue, R.J.

    1995-10-01

    This note discusses the assumptions and results of synchrotron radiation shielding estimates for ALS bend magnet and wiggler beamlines. Estimates of gas bremsstrahlung production are not included and are dealt with elsewhere.

  1. What Is ALS?

    MedlinePlus

    ... scarring or hardening ("sclerosis") in the region. Motor neurons reach from the brain to the spinal cord ... the body. The progressive degeneration of the motor neurons in ALS eventually leads to their demise. When ...

  2. 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.

  3. Response to “Comment on ‘Rethinking first-principles electron transport theories with projection operators: The problems caused by partitioning the basis set’” [J. Chem. Phys. 140, 177103 (2014)

    SciTech Connect

    Reuter, Matthew G.; Harrison, Robert J.

    2014-05-07

    The thesis of Brandbyge's comment [J. Chem. Phys. 140, 177103 (2014)] is that our operator decoupling condition is immaterial to transport theories, and it appeals to discussions of nonorthogonal basis sets in transport calculations in its arguments. We maintain that the operator condition is to be preferred over the usual matrix conditions and subsequently detail problems in the existing approaches. From this operator perspective, we conclude that nonorthogonal projectors cannot be used and that the projectors must be selected to satisfy the operator decoupling condition. Because these conclusions pertain to operators, the choice of basis set is not germane.

  4. COMMENT: Comment on `Structure of supercooled liquid silicon' by Ansell et al

    NASA Astrophysics Data System (ADS)

    Angell, C. A.; Borick, S. S.

    1999-10-01

    We correct a statement made in a recent paper (Angell S et al 1998 J. Phys.: Condens. Matter 10 L73-8) that computer simulations on supercooled liquid silicon were not available. We further point out that the simulations that have been made provide an important confirmation of the findings of Angell et al, from the x-ray diffraction studies, that the Si coordination number rapidly decreases in the supercooling range. Of particular interest is the observation that, at the limit of the 340 K supercooling reported in Angell et al, the laboratory liquid has the same coordination number that the simulated system reaches at the temperature of its first order liquid-liquid transition. This implies that the crystallization is promoted by the liquid-liquid transition, as is also seen in the simulation. We point out other systems in which such provocative behaviour should be found.

  5. Combined HREELS and Raman study of GaAs-AlAs superlattices

    NASA Astrophysics Data System (ADS)

    Tsuruoka, T.; Sekoguchi, M.; Uehara, Y.; Ushioda, S.; Kojima, T.; Ohta, K.

    1994-07-01

    GaAs-AlAs superlattices have been investigated by combining high-resolution electron-energy-loss spectroscopy (HREELS) and Raman spectroscopy. The superlattices were grown on GaAs(100) substrates by molecular-beam epitaxy. The sample surface was protected by an As capping layer formed in situ after growth, so that a well-ordered surface could be obtained by heating the sample mildly in UHV prior to HREELS measurements. The experimental results were compared with the dielectric theory of HREELS reported by Lambin et al. [Phys. Rev. B 32, 8203 (1985)]. The TO phonon frequencies and damping constants of GaAs and AlAs of individual samples, required for the theoretical calculations, were determined by Raman-scattering measurements. Excellent agreement was obtained between the theoretical and experimental results for all the samples with different layer thicknesses and for all the electron impact energies (from 4 to 35 eV) observed.

  6. Modulus measurements in ordered Co-Al, Fe-Al, and Ni-Al alloys

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The composition and/or temperature dependence of the dynamic Young's modulus for the ordered B2 Co-Al, Fe-Al, and Ni-Al aluminides has been investigated using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The modulus has been measured in the composition interval 48.49 to 52.58 at. pct Co, 50.87 to 60.2 at. pct Fe, and 49.22 to 55.95 at. pct Ni for Co-Al, Fe-Al, and Ni-Al, respectively. The measured values for Co-Al are in the temperature interval 300 to 1300 K, while those for the other systems are for ambient temperature only. The data points show that Co-Al is stiffer than Fe-Al, which is stiffer than Ni-Al. The data points for Fe-Al and Ni-Al are slightly higher than those reported in the literature.

  7. Localized magnetic excitation in the hybridization gap of YbAl3

    NASA Astrophysics Data System (ADS)

    Lawrence, J. M.; Goremychkin, E. A.; Bauer, E. D.

    2005-03-01

    YbAl3 is an intermediate valence (IV) compound which enters the coherent Fermi liquid phase below Tcoh = 50K.^[1] We have recently measured the magnetic scattering on the MAPS spectrometer at ISIS using high-quality single crystals. For T < 50K, the data can be fit as the sum of a background of nonmagnetic scattering and a pair of peaks at E1 = 50meV and E2 = 33meV which, in the extended zone scheme, scale with Q as the 4f form factor, as expected for magnetic scattering. The scattering near 50meV exhibits a peak in intensity near Q = (1.2, 0.5, 0.5) which also disperses somewhat with Q. Such Q-dependence is as expected for interband scattering across the hybridization gap in IV compounds. The scattering near 33meV, however, is independent of Q in both intensity and position and hence is the result of a spatially localized excitation. The energy of this excitation coincides with a deep minimum in the optical conductivity^[2], and hence the excitation energy lies in the middle of the hybridization gap. Both the magnetic excitation and the deep minimum in the conductivity gradually disappear above 50K, indicating that they are properties of the renormalized ground state. 1 A. L. Cornelius, et al, Phys. Rev. Lett. 88 (2002) 117201. 2. H. Okamura et al, Journ. Phys. Soc. Japan 73 (2004) 2045.

  8. Ab initio local energy and local stress: application to tilt and twist grain boundaries in Cu and Al.

    PubMed

    Wang, Hao; Kohyama, Masanori; Tanaka, Shingo; Shiihara, Yoshinori

    2013-07-31

    The energy-density and stress-density schemes (Shiihara et al 2010 Phys. Rev. B 81 075441) within the projector augmented wave (PAW) method based on the generalized gradient approximation (GGA) have been applied to tilt and twist grain boundaries (GBs) and single vacancies in Cu and Al. Local energy and local stress at GBs and defects are obtained by integrating the energy and stress densities in each local region by the Bader integration using a recent algorithm (Yu et al 2011 J. Chem. Phys. 134 064111) as well as by the layer-by-layer integration so as to settle the gauge-dependent problem in the kinetic terms. Results are compared with those by the fuzzy-Voronoi integration and by the embedded atom method (EAM). The features of local energy and local stress at GBs and vacancies depend on the bonding nature of each material. Valence electrons in Al mainly located in the interatomic regions show remarkable response to structural disorder as significant valence charge redistribution or bond reconstruction, often leading to long-range variations of charges, energies and stresses, quite differently from d electrons in Cu mainly located near nuclei. All these features can be well represented by our local energy and local stress. The EAM potential for Al does not reproduce correct local energy or local stress, while the EAM potential for Cu provides satisfactory results. PMID:23835349

  9. Hydrogen and Carbon Effects on Al2O3 Surface Phases and Metal Deposition

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Smith, John

    2005-03-01

    Effects of H and C impurities on α-Al2O3 (0001) surface stability and metal wetting behavior are determined from first principles[1]. The ab initio surface phase diagram for H and C on the alumina surface reveals six distinct surface phases. These different surface phases exhibit a variety of adhesion strengths with Cu and Co, and correspondingly different wetting behaviors. These results are consistent with the varied wetting characteristics observed experimentally. [1] Xiao-Gang Wang and John R. Smith, Phys. Rev. B70, Rapid communications, 081401 (2004).

  10. Ordering and growth of rare gas films (Xe, Kr, Ar, and Ne) on the pseudo-ten-fold quasicrystalline approximant Al₁₃Co₄(100) surface.

    PubMed

    Petucci, J; Karimi, M; Huang, Y-T; Curtarolo, S; Diehl, R D

    2014-03-01

    Adsorption of the rare gases Kr, Ar, and Ne on the complex alloy surface Al₁₃Co₄(100) was studied using grand canonical Monte Carlo (GCMC) computer simulations. This surface is an approximant to the ten-fold decagonal Al-Ni-Co quasicrystalline surface, on which rare gas adsorption was studied previously. Comparison of adsorption results on the periodic Al₁₃Co₄(100) surface with those of the quasiperiodic Al-Ni-Co surface indicates some similarities, such as layer-by-layer growth, and some dissimilarities, such as the formation of Archimedes tiling phases (Mikhael et al 2008 Nature 454 501, Shechtman et al 1984 Phys. Rev. Lett. 53 1951, Macia 2006 Rep. Prog. Phys. 69 397, Schmiedeberg et al 2010 Eur. Phys. J. E 32 25-34, Kromer et al 2012 Phys. Rev. Lett. 108 218301, Schmiedeberg and Stark 2008 Phys. Rev. Lett. 101 218302). The conditions under which Archimedes tiling phases (ATP) emerge on Al₁₃Co₄(100) are examined and their presence is related to the gas-gas and gas-surface interaction parameters. PMID:24521558

  11. 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…

  12. ALS renewal moves forward

    NASA Astrophysics Data System (ADS)

    Falcone, R. W.; Feinberg, B.; Hussain, Z.; Kirz, J.; Krebs, G. F.; Padmore, H. A.; Robin, D. S.; Robinson, A. L.

    2007-11-01

    As the result of an extensive long-term planning process involving all its stakeholders—management, staff, and users—the ALS has seen its future and is aggressively moving ahead to implement its vision for keeping the facility at the cutting edge for the next 2-3 decades. The evolving strategic plan now in place aims to renew the ALS so it can address a new generation of fundamental questions about size dependent and dimensional-confinement phenomena at the nanoscale; correlation and complexity in physical, biological, and environmental systems; and temporal evolution, assembly, dynamics and ultrafast phenomena. The renewal spans three areas: (1) increased staffing at beamlines to support the growing user community and safety professionals to keep an increasingly complex facility hazard free; (2) implementing advances in accelerator, insertion device, beamline, and detector technology that will make it possible for ALS users to address emerging grand scientific and technological challenges with incisive world-class tools; and (3) construction of a user support building and guest housing that will increase the safety and user friendliness of the ALS by providing users office, meeting, experiment staging, and laboratory space for their work and on-site accommodations at reasonable rates.

  13. 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

  14. Energy band structure calculations based on screened Hartree-Fock exchange method: Si, AlP, AlAs, GaP, and GaAs.

    PubMed

    Shimazaki, Tomomi; Asai, Yoshihiro

    2010-06-14

    The screening effect on the Hartree-Fock (HF) exchange term plays a key role in the investigation of solid-state materials by first-principles electronic structure calculations. We recently proposed a novel screened HF exchange potential, in which the inverse of the dielectric constant represents the fraction of the HF exchange term incorporated into the potential. We demonstrated that this approach can be used to reproduce the energy band structure of diamond well [T. Shimazaki and Y. Asai, J. Chem. Phys. 130, 164702 (2009)]. In the present paper, we report that the screened HF exchange method is applicable to other semiconductors such as silicon, AlP, AlAs, GaP, and GaAs. PMID:20550388

  15. Existence of traversable wormholes in the spherical stellar systems

    NASA Astrophysics Data System (ADS)

    Övgün, A.; Halilsoy, M.

    2016-07-01

    Potentiality of the presence of traversable wormholes in the outer/inner regions of the halos of galaxies, situated on the Navarro-Frenk-White (NFW) density profile and Universal Rotation Curve (URC) dark matter models have been investigated recently (Rahaman et al. in Eur. Phys. J. C 74:2750, 2014a; Rahaman et al. in Ann. Phys. 350:561-567, 2014b; Kuhfittig in Eur. Phys. J. C 74:2818, 2014a; Kuhfittig in Found. Phys. 7:111-119, 2014b; Kuhfittig in Int. J. Mod. Phys. D 24(03):1550023, 2015; Rahaman et al. in Astrophys. Space Sci. 361(1):37, 2016a; Rahaman et al. in Astrophys. Space Sci. 361(3):90, 2016b). Since this covers our own galaxy also as a possible home for traversable wormholes it prompts us to further the subject by considering alternative density distributions. From this token herein we make use of the Einasto model (Einasto in Tr. Inst. Astrofiz. Alma-Ata 5:87, 1965; Einasto and Haud in Galaxy Astron. Astrophys. 223:89, 1989; Merritt et al. in Astron. J. 132:6, 2006) to describe the density profiles for the same purpose. Our choice for the latter is based on the fact that theoretical dark matter halos produced in computer simulations are best described by such a profile. For technical reasons we trim the number of parameters in the Einasto profile to a possible minimum. Based on such a model it is shown that traversable wormholes in the outer regions of spiral galaxies are possible while the inner part regions prohibit such formations.

  16. Structural investigations of Al5Co2(2 1 ¯ 0 ) and (100) surfaces: Influence of bonding strength and annealing temperature on surface terminations

    NASA Astrophysics Data System (ADS)

    Meier, M.; Ledieu, J.; De Weerd, M.-C.; Fournée, V.; Gaudry, É.

    2016-02-01

    Structural investigations of the (2 1 ¯0 ) and (100) surfaces of Al5Co2 using experimental ultrahigh vacuum techniques and ab initio computational methods are presented in this work. Both surfaces are identified and show bulk terminations where only specific atoms remain. These atoms can be seen as truncated parts of chemically bonded atomic motifs which have been identified in the bulk in a previous work [M. Meier et al., Phys. Rev. B 91, 085414 (2015), 10.1103/PhysRevB.91.085414]. Whereas the (2 1 ¯0 ) surface presents a single termination, the structure of the (100) topmost layers is found to be highly dependent on the preparation conditions, especially on the annealing temperature. This behavior, also observed for the (001) surface studied previously, can be partly explained when considering the bonding strength of the truncated motif parts with the subsurface.

  17. 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.

  18. ALS Project Management Manual

    SciTech Connect

    Krupnick, Jim; Harkins, Joe

    2000-05-01

    This manual has been prepared to help establish a consistent baseline of management practices across all ALS projects. It describes the initial process of planning a project, with a specific focus on the production of a formal project plan. We feel that the primary weakness in ALS project management efforts to date stems from a failure to appreciate the importance of ''up-front'' project planning. In this document, we present a guide (with examples) to preparing the documents necessary to properly plan, monitor, and control a project's activities. While following the manual will certainly not guarantee good project management, failure to address the issues we raise will dramatically reduce the chance of success. Here we define success as meeting the technical goals on schedule and within the prescribed budget.

  19. ALS insertion devices

    SciTech Connect

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

    1990-11-01

    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. 18 refs., 9 figs., 5 tabs.

  20. Ausbildung als zentrale Aufgabe

    NASA Astrophysics Data System (ADS)

    Krämer, Walter; Schmerbach, Sibylle

    Anders als Lesen und Schreiben zählen Grundkenntnisse in Statistik heute noch nicht zu den Voraussetzungen einer sinnvollen Teilhabe am Sozialgeschehen. Und auch in der akademischen Statistik-Ausbildung gibt es noch einiges zu tun. Das vorliegende Kapitel zeichnet die Geschichte dieser akademischen Ausbildung an deutschen Universitäten nach dem zweiten Weltkrieg nach, stellt aktuelle Defizite vor und weist auf mögliche Verbesserungen hin.

  1. Top Quarks Spin Correlations with Graviton in ADD and RS Models at the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Arai, Masato; Okada, Nobuchika; Smolek, Karel; Šimák, Vladislav

    2008-03-01

    In LHC physics we study the spin correlation of top-antitop pairs production to investigate the production mechanism of heavy quarks[F. Hubard et al. Eur. Phys. J. C 44 (2006) 13]. The s-channel process mediated by graviton Kaluza-Klein modes in ADD model with several extra dimensions[N. Arkani-Hamed, S. Dimopoulos and G. Dvali, Phys. Lett. 429B (1998) 263, hep-ph/9803315] or in the Randall-Sundrum model with only one extra dimension[L. Randall and R. Sundrum, Phys. Rev. Lett. 83 (1999) 3370 hep-ph/9905221] contribute to the top-antitop pair production and affects the resulting top spin correlations. We calculated the full density matrix for the top-antitop pair production. We find a sizable deviation of the top spin correlations from the Standard.

  2. Comment on "Effective thermal conductivity of metal and non-metal particulate composites with interfacial thermal resistance at high volume fraction of nano to macro-sized spheres" [J. Appl. Phys. 117, 055104 (2015)

    NASA Astrophysics Data System (ADS)

    Pal, Rajinder

    2015-06-01

    In a recent article, Faroughi and Huber [J. Appl. Phys. 117, 055104 (2015)] propose two theoretical models to compute the effective thermal conductivity of metal and dielectric spherical particle reinforced composites with interfacial thermal resistance. The models are based on the differential effective medium (DEM) theory. The authors have failed to cite and discuss the paper of Pal [Mater. Sci. Eng., A 498, 135-141 (2008)] where similar models have been derived using the same approach (DEM theory). Furthermore, the models proposed by Faroughi and Huber are seriously flawed in that the "excluded volume effect" is taken into account two times, instead of once, in their derivations. Last but not least, there are typos in their models.

  3. Comment on “Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation” [Phys. Fluids 25, 085101 (2013)

    SciTech Connect

    Hietala, Niklas Hänninen, Risto

    2014-01-15

    We comment on the paper by Van Gorder [“Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation,” Phys. Fluids 25, 085101 (2013)]. We point out that the flow of the normal fluid component parallel to the vortex will often lead into the Donnelly–Glaberson instability, which will cause the amplification of the Kelvin wave. We explain why the comparison to local nonlinear equation is unreasonable, and remark that neglecting the motion in the x-direction is not reasonable for a Kelvin wave with an arbitrary wavelength and amplitude. The correct equations in the general case are also derived.

  4. Response to ``Comment on `Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2' '' [J. Appl. Phys. 96, 4656 (2004)

    NASA Astrophysics Data System (ADS)

    Gruber, John B.

    2004-10-01

    We present a reply to the preceding comment made by C. Cascales and C. Zaldo concerning an analysis of the "Spectra and energy levels of Er3+(4f11) in NaBi(WO4)2" [J. Appl. Phys. 94, 7128 (2003)] by J. B. Gruber, Department of Physics, San José State University, San Jose, CA 95192-0106; D. K. Sardar, C. C. Russell III, and R. M. Yow, Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249-0063, B. Zandi, ARL/Adelph Laboratory Center, 2800 Powder Mill Road, Adelphi, Maryland 20783-1197; and E. P. Kokanyan, Institute for Physical Research, Armenian National Academy of Sciences, Ashtarak, Armenia 378410.

  5. Response to 'Comment on 'Resonant dissociative electron transfer of the presolvated electron to CCl{sub 4} in liquid: Direct observation and lifetime of the CCl{sub 4}*{sup -} transition state' [J. Chem. Phys. 129, 027101 (2008)]'

    SciTech Connect

    Wang, C.-R.; Drew, K.; Luo, T.; Lu, M.-J.; Lu, Q.-B.

    2008-07-14

    In our recent paper [J. Chem. Phys.128, 041102 (2008)], we reported a femtosecond time-resolved laser spectroscopic study of the electron transfer reaction of CCl{sub 4} in liquid ethanol. Our results provide direct evidence of the resonant dissociative electron transfer (RDET) of the presolvated electron to CCl{sub 4}, and indicate that RDET can be an efficient process in an aqueous environment. In a recent Comment, the author argues that the relevance of diethanolamine (DEA) induced destruction of chlorofluorocarbons (CFCs) in the polar stratosphere as a possible pathway for chemical ozone destruction should not be a motivation for further studies of DEA on CFC molecules, as no correlation is observed between polar chemical ozone loss and cosmic ray activity. Here, we show that this claim is misleading: it is made by using inconclusive and ambiguous data while ignoring pronounced and well-documented data.

  6. Insulator -- polaron conductor -- metal transitions in a complex oxide 12CaO.7Al2O3.

    NASA Astrophysics Data System (ADS)

    Sushko, P.; Shluger, A.; Stoneham, A.; Hayashi, K.; Matsuishi, S.; Hirano, M.; Hosono, H.

    2006-03-01

    Recent experiments have demonstrated that a complex nano-porous oxide 12CaO.7Al2O3 (C12A7) built of positively charged sub-nanometer cages can be converted from a transparent insulator to a transparent conductor by H2 doping followed by UV-light irradiation with 4--4.5 eV photons [1]. This irradiation induces optical absorption bands with maxima at 0.4 eV and 2.8 eV and high concentrations of unpaired electrons. We use ab initio calculations to reveal the mechanism of photo-induced insulator--conductor transition and the role of H atoms in this process and to elucidate the transport properties of the electrons in this system as a function of electron concentration. Our theoretical modeling suggests that at concentration below 10^20 cm-3 electrons are responsible for the polaron type electrical conductivity with the activation energy close to 0.1 eV as well as for the optical absorption at 0.4 eV and 2.8 eV [2]. We demonstrate that, as the electron concentration exceeds 10^20 cm-3, the character of electronic conductivity changes from polaron type to metallic. [1] K. Hayashi et al., Nature 419, 462 (2002). [2] P.V. Sushko, et al., Phys. Rev. Lett. 91, 126401 (2003); P.V. Sushko et al., Appl. Phys. Lett. 86, 092101 (2005).

  7. Effects of mass anisotropy, thickness and disorder on the spin susceptibility of the 2DEG in AlAs QWs

    NASA Astrophysics Data System (ADS)

    Marchi, Mariapia; de Palo, Stefania; Senatore, Gaetano; Moroni, Saverio

    2008-03-01

    We present predictions of the spin susceptibility χs, obtained from extensive DMC simulations, for a two dimensional (2D) electron gas (EG) with mass anisotropy appropriate to AlAs QWs[1], both in the strictly 2D limit and with thickness included. We demonstrate that in the one-valley case anisotropy suppresses χs substantially at all densities and in particular at those relevant to experiments[1], the effect being larger at lower density. This suppression adds onto the one due to thickness[2,1]. The comparison of our results for a model EG including both thickness and anisotropy with experiments for AlAs QW's[1] reveals the role of disorder in determining the measured spin susceptibility. In the two-valley case we find an interesting interplay of anisotropy and valley degree of freedom in determining the EG properties and in particular the spin susceptibility. [1] T. Gokmen et. al., Phys. Rev. B in press and cond-mat 0711.1294. [2] S. De Palo et. al., Phys. Rev. Lett. 94, 226405 (2005); and to be published

  8. PHYS-MA-TECH. An Integrated Partnership.

    ERIC Educational Resources Information Center

    Scarborough, Jule Dee

    This document contains 45 integrated physics, mathematics, and technology curriculum modules developed by teachers at 5 Illinois schools. An introduction discusses the collaborative project, in which teams of one mathematics, physics, and technology teacher from each school developed innovative instructional delivery models that enabled the three…

  9. Optical gain characteristics in Al-rich AlGaN/AlN quantum wells

    SciTech Connect

    Oto, Takao; Banal, Ryan G.; Funato, Mitsuru; Kawakami, Yoichi

    2014-05-05

    The optical gain characteristics of Al-rich AlGaN/AlN quantum wells (QWs) were assessed by the variable stripe length method at room temperature. An Al{sub 0.79}Ga{sub 0.21}N/AlN QW with a well width of 5 nm had a large optical gain of 140 cm{sup −1}. Increasing the excitation length induced a redshift due to the gain consumption and the consequent saturation of the amplified spontaneous emission. Moreover, a change in the dominant gain polarization with Al composition, which was attributed to switching of the valence band ordering of strained AlGaN/AlN QWs at Al compositions of ∼0.8, was experimentally demonstrated.

  10. 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 ...

  11. Corrigendum to "Resonance scattering of a dielectric sphere illuminated by electromagnetic Bessel non-diffracting (vortex) beams with arbitrary incidence and selective polarizations" [Ann. Phys. 361 (2015) 120-147

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.; Li, R. X.; Guo, L. X.; Ding, C. Y.

    2015-12-01

    In the concerned article Mitri et al. (2015), misprints that have occurred are corrected in six equations. They are Eqs. (60)-(64) and (68). These corrections do neither alter the results and plots displayed in Mitri et al. (2015), nor the conclusions as the numerical computations used the correct equations.

  12. Al(+)-ligand binding energies

    NASA Technical Reports Server (NTRS)

    Sodupe, M.; Bauschlicher, Charles W., Jr.

    1991-01-01

    Ab initio calculations are used to optimize the structure and determine the binding energies of Al(+) to a series of ligands. For Al(+)-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al(+) are compared with those previously reported for Mg(+).

  13. 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.

  14. Dry etching of Al-rich AlGaAs with silicon nitride masks for photonic crystal fabrication

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuyu; Togano, Yuji; Hashimura, Kentaro; Morifuji, Masato; Kondow, Masahiko

    2015-04-01

    We investigate inductively coupled plasma (ICP) deep dry etching of Al0.8Ga0.2As for photonic crystal (PC) fabrication using a Cl2/BCl3/CH4 gas mixture. On the basis of our previous report [Y. Kitabayashi et al., Jpn. J. Appl. Phys. 52, 04CG07 (2013)], we obtained a PC structure having air holes deeper than 1.5 µm and a diameter of 120 nm by adjusting the gas flow rate and increasing the process pressure. In this study, silicon nitride (SiNx) and SiO2 were both used as the mask layer. Furthermore, samples with SiNx and SiO2 masks for ICP deep dry etching were also fabricated and compared. The vertical profile of the PC structure with the SiNx mask layer displayed a rounded shape that was caused by the charge up in the mask layer. Then, a thinner mask layer was used to ease the effects of mask retardation and charge up. As a result, a PC structure with a SiNx mask layer having air holes deeper than 1.7 µm and a diameter of 190 nm was successfully fabricated.

  15. 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.

  16. 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.

  17. Excitonic recombination dynamics in non-polar GaN/AlGaN quantum wells

    SciTech Connect

    Rosales, D.; Gil, B.; Bretagnon, T.; Guizal, B.; Zhang, F.; Okur, S.; Monavarian, M.; Izyumskaya, N.; Avrutin, V.; Özgür, Ü.; Morkoç, H.; Leach, J. H.

    2014-02-21

    The optical properties of GaN/Al{sub 0.15}Ga{sub 0.85}N multiple quantum wells are examined in 8 K–300 K temperature range. Both polarized CW and time resolved temperature-dependent photoluminescence experiment are performed so that we can deduce the relative contributions of the non-radiative and radiative recombination processes. From the calculation of the proportion of the excitonic population having wave vector in the light cone, we can deduce the variation of the radiative decay time with temperature. We find part of the excitonic population to be localized in concert with the report of Corfdir et al. (Jpn. J. Appl. Phys., Part 2 52, 08JC01 (2013)) in case of a-plane quantum wells.

  18. Studies of 27Al NMR in EuAl4

    NASA Astrophysics Data System (ADS)

    Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; Ōnuki, Y.; Harima, H.

    2015-03-01

    EuAl4 orders antiferromagnetically at TN ≈ 16 K with an effective magnetic moment of 8.02 μB. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature θP = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy νQ are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with θP = +14 K, which is consistent with that of the magnetic susceptibility. From the K - χ plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/μB for Al(I) site, and -1.823 and -0.264 kOe/μB for Al(II) site, respectively. The values of νQ of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

  19. Postnatal Depression. A Review. EUR/HFA Target 8.

    ERIC Educational Resources Information Center

    World Health Organization, Copenhagen (Denmark). Regional Office for Europe.

    This document contains three reports on postnatal depression. The first, "The Maternity Blues," by Flemming Warborg Larsen, presents a literature review on the topic. It concludes that most women look back at the "blues" as an episode that was brief, unpleasant, and difficult to explain. The second report, "Postnatal Depressions," by Lene Lier,…

  20. Interfacial characterization of Al-Al thermocompression bonds

    NASA Astrophysics Data System (ADS)

    Malik, N.; Carvalho, P. A.; Poppe, E.; Finstad, T. G.

    2016-05-01

    Interfaces formed by Al-Al thermocompression bonding were studied by the transmission electron microscopy. Si wafer pairs having patterned bonding frames were bonded using Al films deposited on Si or SiO2 as intermediate bonding media. A bond force of 36 or 60 kN at bonding temperatures ranging from 400-550 °C was applied for a duration of 60 min. Differences in the bonded interfaces of 200 μm wide sealing frames were investigated. It was observed that the interface had voids for bonding with 36 kN at 400 °C for Al deposited both on Si and on SiO2. However, the dicing yield was 33% for Al on Si and 98% for Al on SiO2, attesting for the higher quality of the latter bonds. Both a bond force of 60 kN applied at 400 °C and a bond force of 36 kN applied at 550 °C resulted in completely bonded frames with dicing yields of, respectively, 100% and 96%. A high density of long dislocations in the Al grains was observed for the 60 kN case, while the higher temperature resulted in grain boundary rotation away from the original Al-Al interface towards more stable configurations. Possible bonding mechanisms and reasons for the large difference in bonding quality of the Al films deposited on Si or SiO2 are discussed.

  1. 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.

  2. ALS Performance Summary - Update

    SciTech Connect

    Waters, A M; Brown, W D; Martz, Jr., H E

    2004-09-30

    High Energy Density Physics (HEDP) experiments play an important role in corroborating the improved physics codes that underlie LLNL's Stockpile Stewardship mission. Conducting these experiments, whether on the National Ignition Facility (NIF) or another national facility such as Omega, will require not only improvement in the diagnostics for measuring the experiment, but also detailed knowledge of the as-built target components and assemblies themselves. To assist in this effort, a defined set of well-known reference standards designed to represent a range of HEDP targets have been built and are being used to quantify the performance of different characterization techniques [Hibbard, et al. 2004]. Without the critical step of using reference standards for qualifying characterization tools there can be no verification of either commercial or internally-developed characterization techniques and thus an uncertainty in the input to the physics code models would exist.

  3. Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

    NASA Astrophysics Data System (ADS)

    Borges, L. H. C.; Barone, F. A.

    2016-02-01

    Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.

  4. Comment on ‘Exact electromagnetic fields produced by a finite wire with constant current’

    NASA Astrophysics Data System (ADS)

    Ferreira, J. M.; Anacleto, Joaquim

    2016-07-01

    This comment addresses the Jiménez et al paper (2008 Eur. J. Phys. 29 163–75). We correct these authors’ expressions for the electric field and the Poynting vector, and also correct their expressions for the magnetic field. Contrary to the authors, we find that the contribution of the second term in Jefimenko’s formula for the electric field is not zero. These corrections in no way affect the main points made by the authors of the aforementioned paper, and help strengthen their work.

  5. Sivers effect in Drell-Yan processes

    SciTech Connect

    Anselmino, M.; Boglione, M.; Melis, S.; Prokudin, A.; D'Alesio, U.; Murgia, F.

    2009-03-01

    The Sivers distributions recently extracted from semi-inclusive deep inelastic scattering data [M. Anselmino et al., Eur. Phys. J. A 39, 89 (2009)] are used to compute estimates for Sivers asymmetries in Drell-Yan processes which are being planned at several facilities (RHIC, COMPASS, J-PARC, PAX, PANDA, NICA (JINR) and SPASCHARM (IHEP)). Most of these asymmetries turn out to be large and could allow a clear test of the predicted sign change of the Sivers distributions when active in SIDIS and Drell-Yan processes. This is regarded as a fundamental test of our understanding, within QCD and the factorization scheme, of single spin asymmetries.

  6. Isomeric state in {sup 53}Co: A mean field analysis

    SciTech Connect

    Patra, S. K.; Bhat, F. H.; Panda, R. N.; Arumugam, P.; Gupta, Raj K.

    2009-04-15

    We study the ground and the first excited intrinsic states of {sup 53}Co and its mirror nucleus {sup 53}Fe, within the frameworks of the relativistic and nonrelativistic mean field formalisms. The analysis of the single-particle energy spectra of these nuclei show a competition of spins 1/2{sup -} and 3/2{sup -} in a low-lying excited state, which agrees well with the recent experimental observation [D. Rudolph et al., Eur. Phys. J. A 36, 131 (2008)] of spin and parity J{sup {pi}}=3/2{sup -} for the isomeric configuration in {sup 53}Co.

  7. Vibrational properties of C_{20}-based solids

    NASA Astrophysics Data System (ADS)

    Spagnolatti, I.; Mussi, A.; Bernasconi, M.; Benedek, G.

    2004-01-01

    The phonon dispersion relations and IR spectrum of a C{20}-based solid recently identified experimentally [Iqbal et al., Eur. Phys. J. B 31, 509 (2003)] have been computed by density functional perturbation theory. Other competitive structures made by assembling C{20} clusters have been considered as well. In particular, we have computed the structure and the Raman spectra of two-dimensional polymeric phases of hydrogenated C{20} clusters which might be formed under different synthesis conditions. Fingerprints of the different phases have been identified in the vibrational spectra which could be used in the experimental search of C{20}-based solids.

  8. Spectroscopy of the hydrogen 1 S -3 S transition with chirped laser pulses

    NASA Astrophysics Data System (ADS)

    Yost, D. C.; Matveev, A.; Grinin, A.; Peters, E.; Maisenbacher, L.; Beyer, A.; Pohl, R.; Kolachevsky, N.; Khabarova, K.; Hänsch, T. W.; Udem, Th.

    2016-04-01

    We identify a systematic present in two-photon direct frequency comb spectroscopy (DFCS) which is a result of chirped laser pulses and is a manifestation of the first-order Doppler effect. We carefully analyze this systematic and propose methods for its mitigation within the context of our measurement of the hydrogen 1 S -3 S transition. We also report on our determination of the absolute frequency of this transition, which is comparable to a previous measurement using continuous-wave spectroscopy [O. Arnoult et al., Eur. Phys. J. D 60, 243 (2010), 10.1140/epjd/e2010-00249-6], but was obtained with a different experimental method.

  9. Doppelthydrophile Blockcopolymere als Mineralisationstemplate

    NASA Astrophysics Data System (ADS)

    Kasparova, Pavla

    2002-07-01

    Die vorliegende Arbeit beschäftigt sich mit der Synthese und den Eigenschaften von doppelthydrophilen Blockcopolymeren und ihrer Anwendung in einem biomimetischen Mineralisationsprozeß von Calciumcarbonat und Bariumsulfat. Doppelthydrophile Blockcopolymere bestehen aus einem hydrophilen Block, der nicht mit Mineralien wechselwirkt und einem zweiten Polyelektrolyt-Block, der stark mit Mineraloberflächen wechselwirkt. Diese Blockcopolymere wurden durch ringöffnende Polymerisation von N-carboxyanhydriden (NCA's) und a-methoxy-ω-amino[poly(ethylene glycol)] PEG-NH2 als Initiator hergestellt. Die hergestellten Blockcopolymere wurden als effektive Wachstumsmodifikatoren für die Kristallisation von Calciumcarbonat und Bariumsulfat Mineralien eingesetzt. Die so erhaltenen Mineralpartikel (Kugeln, Hantel, eiförmige Partikel) wurden durch Lichtmikroskopie in Lösung, SEM und TEM charakterisiert. Röntgenweitwinkelstreuung (WAXS) wurde verwendet, um die Modifikation von Calciumcarbonat zu ermitteln und die Größe der Calciumcarbonat- und Bariumsulfat-Nanopartikel zu ermitteln. This work describes the synthesis and characterization of double hydrophilic block copolymers and their use in a biomimetic mineralization process of Calcium Carbonate and Barium Sulfate. Double hydrophilic block copolymers consist of a hydrophilic block that does not interact with minerals and another hydrophilic polyelectrolyte block that strongly interacts with mineral surfaces. These polymers were synthesised via ring opening polymerisation of N-carboxyanhydride (NCA), and the first hydrophilic block a-methoxy-ω-amino[poly(ethylene glycol)] PEG-NH2 was used as an initiator. The prepared block copolymers were used as effective crystal growth modifiers to control the crystallization of Calcium Carbonate and Barium Sulfate minerals. The resulting mineral particles (spheres, dumbbells, egg-like particles) were characterised by light microscopy in solution, by SEM, and by TEM. X-Ray scattering

  10. Internal quantum efficiency in yellow-amber light emitting AlGaN-InGaN-GaN heterostructures

    SciTech Connect

    Ngo, Thi Huong; Gil, Bernard; Valvin, Pierre; Damilano, Benjamin; Lekhal, Kaddour; De Mierry, Philippe

    2015-09-21

    We determine the internal quantum efficiency of strain-balanced AlGaN-InGaN-GaN hetero-structures designed for yellow-amber light emission, by using a recent model based on the kinetics of the photoluminescence decay initiated by Iwata et al. [J. Appl. Phys. 117, 075701 (2015)]. Our results indicate that low temperature internal quantum efficiencies sit in the 50% range and we measure that adding an AlGaN layer increases the internal quantum efficiency from 50% up to 57% with respect to the GaN-InGaN case. More dramatic, it almost doubles from 2.5% up to 4.3% at room temperature.

  11. Temporally resolved characterization of shock-heated foam target with Al absorption spectroscopy for fast electron transport study

    SciTech Connect

    Yabuuchi, T.; Sawada, H.; Wei, M. S.; Beg, F. N.; Regan, S. P.; Anderson, K.; Betti, R.; Hund, J.; Paguio, R. R.; Saito, K. M.; Stephens, R. B.; Key, M. H.; Mackinnon, A. J.; McLean, H. S.; Patel, P. K.; Wilks, S. C.

    2012-09-15

    The CH foam plasma produced by a laser-driven shock wave has been characterized by a temporally resolved Al 1s-2p absorption spectroscopy technique. A 200 mg/cm{sup 3} foam target with Al dopant was developed for this experiment, which used an OMEGA EP [D. D. Meyerhofer et al., J. Phys.: Conf. Ser. 244, 032010 (2010)] long pulse beam with an energy of 1.2 kJ and 3.5 ns pulselength. The plasma temperatures were inferred with the accuracy of 5 eV from the fits to the measurements using an atomic physics code. The results show that the inferred temperature is sustained at 40-45 eV between 6 and 7 ns and decreases to 25 eV at 8 ns. 2-D radiation hydrodynamic simulations show a good agreement with the measurements. Application of the shock-heated foam plasma platform toward fast electron transport experiments is discussed.

  12. Structure of V{sub 2}AlC studied by theory and experiment

    SciTech Connect

    Schneider, Jochen M.; Mertens, Raphael; Music, Denis

    2006-01-01

    We have studied V{sub 2}AlC (space group P6{sub 3}/mmc, prototype Cr{sub 2}AlC) by ab initio calculations. The density of states (DOS) of V{sub 2}AlC for antiferromagnetic, ferromagnetic, and paramagnetic configurations have been discussed. According to the analysis of DOS and cohesive energy, no significant stability differences between spin-polarized and non-spin-polarized configurations were found. Based on the partial DOS analysis, V{sub 2}AlC can be classified as a strongly coupled nanolaminate according to our previous work [Z. Sun, D. Music, R. Ahuja, S. Li, and J. M. Schneider, Phys. Rev. B 70, 092102 (2004)]. Furthermore, this phase has been synthesized in the form of thin films by magnetron sputtering. The equilibrium volume, determined by x-ray diffraction, is in good agreement with the theoretical data, implying that ab initio calculations provide an accurate description of V{sub 2}AlC.

  13. Interfacial reactions and oxidation behavior of Al 2O 3 and Al 2O 3/Al coatings on an orthorhombic Ti 2AlNb alloy

    NASA Astrophysics Data System (ADS)

    Li, H. Q.; Wang, Q. M.; Gong, J.; Sun, C.

    2011-02-01

    The uniform and dense Al2O3 and Al2O3/Al coatings were deposited on an orthorhombic Ti2AlNb alloy by filtered arc ion plating. The interfacial reactions of the Al2O3/Ti2AlNb and Al2O3/Al/Ti2AlNb specimens after vacuum annealing at 750 °C were studied. In the Al2O3/Ti2AlNb specimens, the Al2O3 coating decomposed significantly due to reaction between the Al2O3 coating and the O-Ti2AlNb substrate. In the Al2O3/Al/Ti2AlNb specimens, a γ-TiAl layer and an Nb-rich zone came into being by interdiffusion between the Al layer and the O-Ti2AlNb substrate. The γ-TiAl layer is chemically compatible with Al2O3, with no decomposition of Al2O3 being detected. No internal oxidation or oxygen and nitrogen dissolution zone was observed in the O-Ti2AlNb alloy. The Al2O3/Al/Ti2AlNb specimens exhibited excellent oxidation resistance at 750 °C.

  14. Model for roughening and ripple instability due to ion-induced mass redistribution [Addendum to H. Hofsäss, Appl. Phys. A 114 (2014) 401, "Surface instability and pattern formation by ion-induced erosion and mass redistribution"

    NASA Astrophysics Data System (ADS)

    Hofsäss, Hans

    2015-05-01

    Carter and Vishnyakov introduced a model (CV model) to describe roughening and ripple instability due to ion-induced mass redistribution. This model is based on the assumption that the irradiated surface layer on a static solid substrate is described by a viscous incompressible thin film bound to the substrate by a "no slip" and "no transport" kinematic boundary condition, i.e. similar to a thin film of viscous paint. However, this boundary condition is incomplete for a layer under ion irradiation. The boundary condition must allow exchange of atoms between the substrate and the irradiated film, so that the thickness of the film is always determined by the size of the collision cascade, independent of the evolution of the surface height profile. In addition, the film thickness depends on the local ion incidence angle, which leads to a time dependence of the film thickness at a given position. The equation of motion of the surface and interface profiles for these boundary conditions is introduced, and a new curvature-dependent coefficient is found which is absent in the CV model. This curvature coefficient depends on the angular derivative of the layer thickness and the atomic drift velocity at the film surface induced by recoil events. Such a stabilizing curvature coefficient was introduced in Appl. Phys. A 114 (2014) 401 and is most pronounced at intermediate angles.

  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. Special issue: diagnostics of atmospheric pressure microplasmas

    NASA Astrophysics Data System (ADS)

    Bruggeman, Peter; Czarnetzki, Uwe; Tachibana, Kunihide

    2013-11-01

    464004 [14] Sousa J S and Puech V 2013 J. Phys. D: Appl. Phys. 46 464005 [15] Takeda K et al 2013 J. Phys. D: Appl. Phys. 46 464006 [16] Vallade J and Massines F 2013 J. Phys. D: Appl. Phys. 46 464007 [17] Wang C and Wu W 2013 J. Phys. D: Appl. Phys. 46 464008 [18] Schröter S et al 2013 J. Phys. D: Appl. Phys. 46 464009 [19] Rusterholtz D L et al 2013 J. Phys. D: Appl. Phys. 46 464010 [20] Huang B-D et al 2013 J. Phys. D: Appl. Phys. 46 464011 [21] Pothiraja R et al 2013 J. Phys. D: Appl. Phys. 46 464012 [22] Marinov I et al 2013 J. Phys. D: Appl. Phys. 46 464013 [23] Akishev Y et al 2013 J. Phys. D: Appl. Phys. 46 464014 [24] Brandenburg R et al 2013 J. Phys. D: Appl. Phys. 46 464015 [25] Houlahan T J Jret al 2013 J. Phys. D: Appl. Phys. 46 464016 [26] Benedikt J et al 2013 J. Phys. D: Appl. Phys. 46 464017 [27] McKay K et al 2013 J. Phys. D: Appl. Phys. 46 464018 [28] Selected papers from the 2nd International Workshop on Microplasmas 2005 J. Phys. D: Appl. Phys. 38 1633-759 [29] Special issue: 3rd International Workshop on Microplasmas 2007 Control. Plasma Phys. 47 3-128 [30] Cluster issue on Microplasmas: 4th International Workshop on Microplasmas 2008 J. Phys. D: Appl. Phys. 41 1904001 [31] Microplasmas: scientific challenges and technological opportunities 2010 Eur. Phys. J. D 60 437-608 [32] Becker K H, Schoenbach K H and Eden J G 2006 J. Phys. D: Appl. Phys. 39 R55 [33] Iza F, Kim G J, Lee S M, Lee J K, Walsh J L, Zhang Y T and Kong M G 2008 Plasma Process. Polym. 5 322-44 [34] Tachibana K 2006 Trans. Electr. Electron. Eng. 1 145-55 [35] Samukawa S et al 2012 J. Phys. D: Appl. Phys. 45 253001

  17. 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.

  18. Undulators at the ALS

    SciTech Connect

    Hoyer, E.; Akre, J.; Chin, J.

    1994-07-01

    At Lawrence Berkeley Laboratory`s (LBL) Advanced Light Source (ALS), three 4.6 m long undulators have been completed, tested and installed. A fourth is under construction. The completed undulators include two 5.0 cm period length, 89 period devices (U5.0s) which achieve a 0.85 T effective field at a 14 mm minimum gap and a 8.0 cm period length, 55 period device (U8.0) that reaches a 1.2 T effective field at a 14 mm minimum gap. The undulator under construction is a 10.0 cm period length, 43 period device (U10.0) that is designed to achieve 0.98 T at a 23 mm gap. Undulator magnetic gap variation (rms) is within 25 microns over the periodic structure length. Reproducibility of the adjustable magnetic gap has been measured to be within +/{minus} 5 microns. Gap adjusting range is from 14 mm to 210 mm, which can be scanned in one minute. The 5.1 m long vacuum chambers are flat in the vertical direction to within 0.74 mm and straight in the horizontal direction to within 0.08 mm over the 4.6 m magnetic structure sections. Vacuum chamber base pressures after UHV beam conditioning are. in the mid 10{sup {minus}11} Torr range and storage ring operating pressures with full current are in the low 10{sup {minus}10} Torr range. Measurements show that the uncorrelated magnetic field errors are 0.23%, and 0.20% for the two U5.Os and the U8.0 respectively and that the field integrals are small over the 1 cm by 6 cm beam aperture. Device description, fabrication, and measurements are presented.

  19. Calculation of the electron affinities of the second row atoms: Al--Cl

    SciTech Connect

    Woon, D.E.; Dunning, T.H. Jr. )

    1993-09-01

    The electron affinities (EAs) of aluminum through chlorine have been calculated with multireference single and double excitation configuration interaction calculations (MRSD-CI) with the augmented correlation consistent basis sets of Woon and Dunning [J. Chem. Phys. [bold 98], 1358 (1993)]. The orbital space for the complete active space (CAS) wave functions is systematically expanded beyond the Hartree--Fock wave function by inclusion of additional [ital s], [ital p], and [ital d] orbitals. This approach provides a well balanced treatment of the neutral and ionic charge states and led to accurate EAs for hydrogen and the first row atoms [R. A. Kendall, T. H. Dunning, Jr., and R. J. Harrison, J. Chem. Phys. [bold 96], 6796 (1992)]. The best MRSD-CI values for the EAs (in eV) of the second row atoms are Al, 0.440; Si, 1.413; P, 0.689; S, 2.023; and Cl, 3.606. Inclusion of spin--orbit effects in the calculated EAs yields (experimental values in parentheses): Al, 0.437 (0.441); Si, 1.395 (1.385); P, 0.700 (0.746); S, 2.019 (2.077); and Cl, 3.570 (3.613). The amenability of the correlation consistent basis sets for extrapolating to the complete basis set limit has also been exploited in this work. The neutral and anion energies are extrapolated separately in order to account for the different convergence rates in the energies of the two species. The extrapolated values of the EAs, including an empirical spin--orbit correction, are Al, 0.438; Si, 1.395; P, 0.713; S, 2.047; and Cl, 3.596. Additional calculations suggest that the remaining error is a measure of the residual imbalance in the MRSD-CI treatments of the neutral and anion. Extrapolated EAs for the first row atoms are also reported.

  20. 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.

    2016-07-01

    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.

  1. Modeling neuronal vulnerability in ALS.

    PubMed

    Roselli, Francesco; Caroni, Pico

    2014-08-20

    Using computational models of motor neuron ion fluxes, firing properties, and energy requirements, Le Masson et al. (2014) reveal how local imbalances in energy homeostasis may self-amplify and contribute to neurodegeneration in ALS. PMID:25144872

  2. 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.

  3. 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.

  4. Jack Steinberger: Memories of the PS and of LEP

    NASA Astrophysics Data System (ADS)

    Tsesmelis, Emmanuel

    2012-03-01

    This contribution, a personal recollection by the author, is part of a special issue - CERN's accelerators, experiments and international integration 1959-2009. Guest Editor: Herwig Schopper [Schopper, Herwig. 2011. Editorial. Eur. Phys. J. H 36: 437

  5. LETTERS AND COMMENTS: Note on the 'log formulae' for pendulum motion valid for any amplitude

    NASA Astrophysics Data System (ADS)

    Qing-Xin, Yuan; Pei, Ding

    2010-01-01

    In this note, we present an improved approximation to the solution of Lima (2008 Eur. J. Phys. 29 1091), which decreases the maximum relative error from 0.6% to 0.084% in evaluating the exact pendulum period.

  6. K -shell ionization cross sections of Al, Si, S, Ca, and Zn for oxygen ions in the energy range 1. 1--8 MeV

    SciTech Connect

    Geretschlaeger, M. ); Smit, Z. ); Steinbauer, E. )

    1992-03-01

    {ital K}-shell ionization cross sections induced by 1.1--8-MeV oxygen ions in Al, Si, S, Ca, and Zn were measured using different target thicknesses. The cross sections for vanishingly thin and for charge-equilibrium targets were obtained by extrapolation. The experimental results are compared to the perturbed stationary-state approximation with energy-loss, Coulomb, and relativistic corrections (ECPSSR) cross sections (Brandt and Lapicki, Phys. Rev. A 23, 1717 (1981)), to the modification of the ECPSSR theory (MECPSSR) (Benka, Geretschlaeger, and Paul, J. Phys. (Paris) Colloq. Suppl. 12, C9-251 (1987)), to the theory for direct Coulomb ionization of the 1{ital s}{sigma} molecular orbital (Montenegro and Sigaud, J. Phys. B 18, 299 (1985)), and to several semiclassical approximation codes using either the united atom binding procedure or the variational approach of Andersen {ital et} {ital al}. (Nucl. Instrum. Methods 192, 79 (1982)). The cross sections were also compared to the statistical molecular-orbital theory of inner-shell ionization for (nearly) symmetric atomic collisions (Mittelman and Wilets, Phys. Rev. 154, 12 (1967)). For fast collisions ({xi}{similar to}1), the ionization cross sections are well reproduced by theories for direct Coulomb ionization. For slower collisions ({xi}{lt}1), the experimental cross sections are systematically higher than the direct-ionization values, but they agree satisfactorily with the summed cross sections for direct Coulomb ionization and for molecular-orbital ionization. Best agreement (within a factor of 2) was found for the sums of MECPSSR and statistical cross sections.

  7. Thermal vacancy formation and positron-vacancy interaction in Ti3Al at high temperatures

    NASA Astrophysics Data System (ADS)

    Würschum, R.; Kümmerle, E. A.; Badura-Gergen, K.; Seeger, A.; Herzig, Ch.; Schaefer, H.-E.

    1996-07-01

    In order to study the formation of thermal vacancies in the Ti-Al alloy system, high-temperature positron lifetime measurements together with a modeling of defect formation in the framework of nearest-neighbor pair bonds were performed for α2Ti3Al and compared to recent results on γTiAl [U. Brossmann, R. Würschum, K. Badura, and H.-E. Schaefer, Phys. Rev. B 49, 6457 (1994)]. Substantial increases of the positron lifetime τ were observed for Ti65.6Al34.4 and Ti77.1Al22.9 in the temperature range T≳1200 K where thermal vacancy concentrations above the detection limit of positron annihilation are expected from the model calculations for the α2 phase. Within the high-temperature increase of the positron lifetime in the α2 and the β phase single-component positron lifetime spectra were observed. This behavior is in contrast to the two-component spectra observed conventionally at intermediate positron trapping rates and is attributed to a fast detrapping and retrapping of positrons at vacancies due to a low positron-vacancy binding energy. For this case, a vacancy formation enthalpy of HFV=(1.55±0.2) eV in α2Ti65.6Al34.4 and HFV=(1.8±0.2) eV in βTi77.1Al22.9 can be derived. These results are discussed in the context of recent 44Ti tracer diffusion studies.

  8. Conduction electron spin resonance in the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds

    NASA Astrophysics Data System (ADS)

    Holanda, L. M.; Lesseux, G. G.; Magnavita, E. T.; Ribeiro, R. A.; Nakatsuji, S.; Kuga, K.; Fisk, Z.; Oseroff, S. B.; Urbano, R. R.; Rettori, C.; Pagliuso, P. G.

    2015-06-01

    β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb3+ local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB4 possesses a previously known structural variant, namely the α-YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB4. For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB4. This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal.

  9. Stimulated emission in AlGaN/AlGaN quantum wells with different Al content

    NASA Astrophysics Data System (ADS)

    Mickevičius, J.; Jurkevičius, J.; Kazlauskas, K.; Žukauskas, A.; Tamulaitis, G.; Shur, M. S.; Shatalov, M.; Yang, J.; Gaska, R.

    2012-02-01

    Stimulated emission (SE) is studied in AlGaN/AlGaN multiple quantum wells (MQWs) with different Al content grown on sapphire substrate. The spectra of spontaneous and stimulated emission and their transformations with increasing temperature as well as stimulated emission thresholds were measured in the temperature range from 8 to 300 K. Phonon-assisted band broadening in low-Al-content MQWs and double-scaled potential profile in high-Al-content MQWs were observed in the samples and linked with carrier localization conditions. The temperature dependence of the stimulated emission threshold was similar in the samples where the stimulated transitions occur between extended states and in the samples where the transitions occur in localized states. The stimulated emission threshold depends predominantly on the density of nonradiative recombination centers.

  10. Corrigendum to Aerosol impacts on California winter clouds and precipitation during CalWater 2011: local pollution versus long-range transported dust published in Atmos. Chem. Phys., 14, 81–101, 2014

    SciTech Connect

    Fan, Jiwen; Leung, Lai-Yung R.; DeMott, Paul J.; Comstock, Jennifer M.; Singh, Balwinder; Rosenfeld, Daniel; Tomlinson, Jason M.; White, A.; Prather, Kimberly; Minnis, Patrick; Ayers, J. K.; Min, Qilong

    2014-05-01

    In the paper “Aerosol impacts on California winter clouds and precipitation during CalWater 2011: local pollution versus long-range transported dust” by J. Fan et al., wrong versions of Fig. 8 and Fig. 12 were published. Please find the correct figures below.

  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. 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.

  13. 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.

  14. Microwave cyclotron resonance of two-dimensional holes in GaAs/AlGaAs quantum wells on (100) substrates

    NASA Astrophysics Data System (ADS)

    Zhu, Han; Lai, K.; Tsui, D. C.; Ong, N. P.; Manfra, M.; Pfeiffer, L.; West, K.

    2006-03-01

    Cyclotron resonance at microwave frequencies is used to measure the band mass (mb) of two-dimensional holes (2DH’s) in the GaAs/AlxGa1-xAs quantum wells grown on (100) GaAs substrates [1]. The measured mb shows strong dependences on both the 2DH density (p) and the well width (W). For a fixed W, in the density range (0.4x10^11 to 1.1x10^11cm-2) studied here, mb increases with p, consistent with previous studies of the 2DH’s on the (311)A surface [2]. However, the density dependence is significantly weaker on the (100) surface than that on the (311)A surface for the same well width of 30nm. For a fixed p = 1.1x10^11cm-2, mb increases from 0.22me at W = 10nm to 0.54 me at W = 20nm, and stays around 0.51me for W up to 1000nm. With the transport measurement at 0.3K in the dark, the DC scattering time τDC deduced for p = 1.1x10^11cm-2 shows a maximum of 0.6ns at W = 20nm. [1] M. J. Manfra et al., Appl. Phys. Lett. 86, 16 (2005). [2] W. Pan et al., Appl. Phys. Lett. 83, 3519 (2003).

  15. News Report: The career paths of physics graduates Education: Network day to hold workshops for teaching ideas Experiments: PhysHOME brings innovators together Meeting: Physics Education Networks collaborate at WCPE Workshop: World experts in physics education meet Training: Something for everyone at SPEED 2012 Conference: Sun, cocktails and physics create a buzz at WCPE Students: The physics paralympian 2012 Forthcoming events

    NASA Astrophysics Data System (ADS)

    2012-09-01

    Report: The career paths of physics graduates Education: Network day to hold workshops for teaching ideas Experiments: PhysHOME brings innovators together Meeting: Physics Education Networks collaborate at WCPE Workshop: World experts in physics education meet Training: Something for everyone at SPEED 2012 Conference: Sun, cocktails and physics create a buzz at WCPE Students: The physics paralympian 2012 Forthcoming events

  16. PhysDoc: A Distributed Network of Physics Institutions: Collecting, Indexing, and Searching High Quality Documents by Using Harvest; The Dublin Core Metadata Initiative: Mission, Current Activities, and Future Directions; Information Services for Higher Education: A New Competitive Space; Intellectual Property Conservancies.

    ERIC Educational Resources Information Center

    Severiens, Thomas; Hohlfeld, Michael; Zimmermann, Kerstin; Hilf, Eberhard R.; von Ossietzky, Carl; Weibel, Stuart L.; Koch, Traugott; Hughes, Carol Ann; Bearman, David

    2000-01-01

    Includes four articles that discuss a variety to topics, including a distributed network of physics institutions documents called PhysDocs which harvests information from the local Web-servers of professional physics institutions; the Dublin Core metadata initiative; information services for higher education in a competitive environment; and…

  17. 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.

  18. Corrosion Behavior of Al-Al3Ni and Al-Al2Cu Functionally Graded Materials Fabricated by a Centrifugal Method

    NASA Astrophysics Data System (ADS)

    Noda, Kazuhiko; Miyahara, Keita; Watanabe, Yoshimi

    2008-02-01

    Intermetallic compounds, such as Al3Ni and Al2Cu, are effective for enhancing the mechanical properties of an alloy. Al-Al3Ni and Al-Al2Cu functionally graded materials (FGMs) might be attractive materials for advanced materials. Al-Al3Ni and Al-Al2Cu FGMs were fabricated by a centrifugal method; the centrifugal method is an extremely effective method for fabricating FGMs. Al-Al3Ni and Al-Al2Cu FGMs that had a graded distribution of intermetallic compounds could be produced by this in-situ centrifugal method. Particle size, particle shape and the distribution of intermetallic compounds were controlled by varying the content of the alloy element (Ni, Cu) in the master alloy, the cooling rate in casting and the gravity number. The casting mechanism is explained in terms of the microstructures of the Al-Al3Ni and Al-Al2Cu FGMs fabricated by this method. The corrosion behavior of the FGMs was investigated by electrochemical analysis. Polarization curves of the FGMs in a borate solution were measured by a potentiodynamic method. The presence of Al2Cu exerted a larger effect on the corrosion behavior of the FGMs than Al3Ni. Analysis of the polarization curve parameters was effective for evaluating the corrosion resistance of the FGMs.

  19. Reply to ``Comment on `Anti-cooperativity in hydrophobic interactions: A simulation study of spatial dependence of three-body effects and beyond' '' [J. Chem. Phys. 116, 2665 (2002)

    NASA Astrophysics Data System (ADS)

    Shimizu, Seishi; Chan, Hue Sun

    2002-02-01

    An accurate, physically justifiable procedure for determining zero-PMF baselines is essential in addressing the important issue of anti-cooperativity or cooperativity in hydrophobic interactions. For this purpose, the test-particle insertion technique is less dependent on unproven assumptions than other procedures. Its application is recommended for studies in which the technique is computationally feasible. We agree with Czaplewski et al. that much remains to be learned about hydrophobic interactions nonadditivity, and that sustained efforts are needed to overcome numerical uncertainties in the simulation results reported thus far. Nonetheless, with data available to date, there is apparently stronger support for anti-cooperativity than for cooperativity for a significant fraction of solute configurations of the three-methane system in question. This is illustrated by a reanalysis of a three-methane PMF reported previously by Czaplewski et al. [Protein Sci. 9, 1235 (2000)] in light of the new two-methane PMF presented in their Comment.

  20. Corrigendum to "Aerosol indirect effects from shipping emissions: sensitivity studies with the global aerosol-climate model ECHAM-HAM" published in Atmos. Chem. Phys., 12, 5985-6007, 2012

    NASA Astrophysics Data System (ADS)

    Peters, K.; Stier, P.; Quaas, J.; Graßl, H.

    2013-07-01

    An error in the calculation of the emitted number of primary sulfate particles for a given mass of emitted elementary sulfur has recently been identified in HAM, i.e. the aerosol module utilised in the ECHAM-HAM aerosol climate model. Correcting for this error substantially alters the estimates of top-of-atmosphere radiative forcing due to aerosol indirect effects from global shipping emissions (year 2000) as presented in Peters et al. (2012). Here, we shortly present these new results.

  1. Erratum to "Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23-Paper 1" [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2009-01-01

    One of the figures (Fig. 4) in "Solar sources and geospace consequences of interplanetary magnetic Clouds observed during solar cycle 23 -- Paper 1" by Gopalswamy et al. (2008, JASTP, Vol. 70, Issues 2-4, February 2008, pp. 245-253) is incorrect because of a software error in t he routine that was used to make the plot. The source positions of various magnetic cloud (MC) types are therefore not plotted correctly.

  2. Electronic structure of Sc 2AC (A=Al, Ga, In, Tl)

    NASA Astrophysics Data System (ADS)

    Music, Denis; Sun, Zhimei; Schneider, Jochen M.

    2005-02-01

    Using ab initio calculations, we have studied Sc 2AC with A=Al, Ga, In and Tl. We show that C 2p and Sc 3d as well as A p and Sc 3d states are hybridized, but the antibonding states in the vicinity of the Fermi level weaken the overall bonding. In terms of the chemical bonding, the influence of the size of the A element is minute. Furthermore, the bulk modulus of the corresponding binary transition metal carbide is not conserved in these phases. Therefore, Sc 2AC can be classified as weakly coupled MAX phases according to Sun and co-workers [Z. Sun, D. Music, R. Ahuja, S. Li, J.M. Schneider, Phys. Rev. B 70 (2004) 092102]. It is our ambition that these calculations will stimulate experimental research on these compounds.

  3. Hydrogen bridging in the compounds X2H (X=Al,Si,P,S)

    NASA Astrophysics Data System (ADS)

    Owens, Zachary T.; Larkin, Joseph D.; Schaefer, Henry F.

    2006-10-01

    X2H hydrides (X =Al, Si, P, and S) have been investigated using coupled cluster theory with single, double, and triple excitations, the latter incorporated as a perturbative correction [CCSD(T)]. These were performed utilizing a series of correlation-consistent basis sets augmented with diffuse functions (aug-cc-pVXZ, X =D, T, and Q). Al2H and Si2H are determined to have H-bridged C2v structures in their ground states: the Al2H ground state is of B12 symmetry with an Al-H-Al angle of 87.6°, and the Si2H ground state is of A12 symmetry with a Si-H-Si angle of 79.8°. However, P2H and S2H have nonbridged, bent Cs structures: the P2H ground state is of A'2 symmetry with a P-P-H angle of 97.0°, and the S2H ground state is of A'2 symmetry with a S-S-H angle of 93.2°. Ground state geometries, vibrational frequencies, and electron affinities have been computed at all levels of theory. Our CCSD(T)/aug-cc-pVQZ adiabatic electron affinity of 2.34eV for the Si2H radical is in excellent agreement with the photoelectron spectroscopy experiments of Xu et al. [J. Chem. Phys. 108, 7645 (1998)], where the electron affinity was determined to be 2.31±0.01eV.

  4. 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). PMID:23248170

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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. The formation of a zincblende AlN thin film is determined to be a kinetically driven process, not a thermodynamically driven process.

  6. High Density Sliding at Ta/Al and Al/Al Interfaces

    SciTech Connect

    Hammerberg, J. E.; Germann, T. C.; Ravelo, R.

    2006-07-28

    We present 3D-nonequilibrium molecular dynamics results for the velocity dependence of the frictional force at smooth sliding interfaces for Ta and Al single crystals. For Ta/Al we consider Al(100)/Ta(100) and Al(111)/Ta(110) interfaces sliding along [001] and [11(bar sign)0]fcc /[001]bcc respectively. These are compared with Al(111)/Al(100) interfaces at the same loads, corresponding to a pressure of 15 GPa. Both interfacial pairs show similar behavior in the velocity dependence of the frictional force: a low velocity regime with an increasing frictional force followed by a strain induced transformation regime at velocities above approximately 1/10 the transverse sound speed, followed by a fluidized interface at high velocities. For both interfacial pairs, the high velocity dependence of the frictional force exhibits power law behavior, Ft {proportional_to} v-{beta} with {beta}=3/4. We discuss the structural changes that influence dissipation in each of these regimes.

  7. Fluctuations and symmetries in two-dimensional active gels.

    PubMed

    Sarkar, N; Basu, A

    2011-04-01

    Motivated by the unique physical properties of biological active matter, e.g., cytoskeletal dynamics in eukaryotic cells, we set up effective two-dimensional (2d) coarse-grained hydrodynamic equations for the dynamics of thin active gels with polar or nematic symmetries. We use the well-known three-dimensional (3d) descriptions (K. Kruse et al., Eur. Phys. J. E 16, 5 (2005); A. Basu et al., Eur. Phys. J. E 27, 149 (2008)) for thin active-gel samples confined between parallel plates with appropriate boundary conditions to derive the effective 2d constitutive relations between appropriate thermodynamic fluxes and generalised forces for small deviations from equilibrium. We consider three distinct cases, characterised by spatial symmetries and boundary conditions, and show how such considerations dictate the structure of the constitutive relations. We use these to study the linear instabilities, calculate the correlation functions and the diffusion constant of a small tagged particle, and elucidate their dependences on the activity or nonequilibrium drive. PMID:21533956

  8. Many-Body Effect in Spin Dephasing in n-Type GaAs Quantum Wells

    NASA Astrophysics Data System (ADS)

    Weng, Ming-Qi; Wu, Ming-Wei

    2005-03-01

    By constructing and numerically solving the kinetic Bloch equations we perform a many-body study of the spin dephasing due to the D'yakonov-Perel' effect in n-type GaAs (100) quantum wells for high temperatures. In our study, we include the spin-conserving scattering such as the electron-phonon, the electron-nonmagnetic impurity as well as the electron-electron Coulomb scattering into consideration. The dephasing obtained from our theory contains both the single-particle and the many-body contributions with the latter originating from the inhomogeneous broadening introduced by the DP term [J. Supercond.: Incorp. Novel Magn. 14 (2001) 245 Eur. Phys. J. B 18 (2000) 373]. Our result agrees very well with the experimental data [Phys. Rev. B 62 (2000) 13034] of Malinowski et al. We further show that in the case we study, the spin dephasing is dominated by the many-body effect.

  9. 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.

  10. 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.

  11. AlN/Fe/AlN nanostructures for magnetooptic magnetometry

    SciTech Connect

    Lišková-Jakubisová, E. Višňovský, Š.; Široký, P.; Hrabovský, D.; Pištora, J.

    2014-05-07

    AlN/Fe/AlN/Cu nanostructures with ultrathin Fe grown by sputtering on Si substrates are evaluated as probes for magnetooptical (MO) mapping of weak currents. They are considered for a laser wavelength of λ = 410 nm (3.02 eV) and operate at oblique light incidence angles, φ{sup (0)}, to enable detection of both in-plane and out-of-plane magnetization. Their performance is evaluated in terms of MO reflected wave electric field amplitudes. The maximal MO amplitudes in AlN/Fe/AlN/Cu are achieved by a proper choice of layer thicknesses. The nanostructures were characterized by MO polar Kerr effect at φ{sup (0)} ≈ 5° and longitudinal Kerr effect spectra (φ{sup (0)} = 45°) at photon energies between 1 and 5 eV. The nominal profiles were refined using a model-based analysis of the spectra. Closed form analytical expressions are provided, which are useful in the search for maximal MO amplitudes.

  12. Effect of Hydrogen on Interfacial Structure and Adhesion of Metal/Al_2O_3

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Gang; Scheffler, Matthias

    2001-03-01

    Metal/sapphire interfaces have been intensively studying because of their importance in many technological applications. A large work of adhesion was found for the oxygen-terminated Al_2O_3(0001)/metal interfaces. As well known, the clean oxygen-terminated Al_2O3 surface is not stable even under a high oxygen pressure[1]. The understanding of how the oxygen-terminated interfaces can be formed is limited. Using an ab initio full-potential linearized augmented plane wave method, we investigated the effect of hydrogen on the formation of metal/Al_2O_3(0001) interfaces. Our results reveal that hydrogen plays an important role in the formation of the oxygen-terminated interfaces. Hydrogen impurities greatly decrease the work of adhesion. The behavior of hydrogen in deposition process of ultrathin metal films on sapphire substrates and the possible structures of the ultrathin films are discussed also. [1] Xiao-Gang Wang, Anne Chaka, Matthias Scheffler, Phys. Rev. Lett. 84, 3650 (2000).

  13. Temperature-dependent stability of stacking faults in Al, Cu and Ni: first-principles analysis.

    PubMed

    Bhogra, Meha; Ramamurty, U; Waghmare, Umesh V

    2014-09-24

    We present comparative analysis of microscopic mechanisms relevant to plastic deformation of the face-centered cubic (FCC) metals Al, Cu, and Ni, through determination of the temperature-dependent free energies of intrinsic and unstable stacking faults along [1 1̄ 0] and [1 2̄ 1] on the (1 1 1) plane using first-principles density-functional-theory-based calculations. We show that vibrational contribution results in significant decrease in the free energy of barriers and intrinsic stacking faults (ISFs) of Al, Cu, and Ni with temperature, confirming an important role of thermal fluctuations in the stability of stacking faults (SFs) and deformation at elevated temperatures. In contrast to Al and Ni, the vibrational spectrum of the unstable stacking fault (USF[1 2̄ 1]) in Cu reveals structural instabilities, indicating that the energy barrier (γusf) along the (1 1 1)[1 2̄ 1] slip system in Cu, determined by typical first-principles calculations, is an overestimate, and its commonly used interpretation as the energy release rate needed for dislocation nucleation, as proposed by Rice (1992 J. Mech. Phys. Solids 40 239), should be taken with caution. PMID:25185834

  14. Temperature-dependent stability of stacking faults in Al, Cu and Ni: first-principles analysis

    NASA Astrophysics Data System (ADS)

    Bhogra, Meha; Ramamurty, U.; Waghmare, Umesh V.

    2014-09-01

    We present comparative analysis of microscopic mechanisms relevant to plastic deformation of the face-centered cubic (FCC) metals Al, Cu, and Ni, through determination of the temperature-dependent free energies of intrinsic and unstable stacking faults along [1 \\bar{1} 0] and [1 \\bar{2} 1] on the (1 1 1) plane using first-principles density-functional-theory-based calculations. We show that vibrational contribution results in significant decrease in the free energy of barriers and intrinsic stacking faults (ISFs) of Al, Cu, and Ni with temperature, confirming an important role of thermal fluctuations in the stability of stacking faults (SFs) and deformation at elevated temperatures. In contrast to Al and Ni, the vibrational spectrum of the unstable stacking fault (USF_{[1\\,\\bar{2}\\,1]}) in Cu reveals structural instabilities, indicating that the energy barrier (γusf) along the (1 1 1)[1 \\bar{2} 1] slip system in Cu, determined by typical first-principles calculations, is an overestimate, and its commonly used interpretation as the energy release rate needed for dislocation nucleation, as proposed by Rice (1992 J. Mech. Phys. Solids 40 239), should be taken with caution.

  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. Taylor-Couette flow control by amplitude variation of the inner cylinder cross-section oscillation

    NASA Astrophysics Data System (ADS)

    Oualli, Hamid; Mekadem, Mahmoud; Lebbi, Mohamed; Bouabdallah, Ahcene

    2015-07-01

    The hydrodynamic stability of a viscous fluid flow evolving in an annular space between a rotating inner cylinder with a periodically variable radius and an outer fixed cylinder is considered. The basic flow is axis-symmetric with two counter-rotating vortices each wavelength along the whole filled system length. The numerical simulations are implemented on the commercial Fluent software package, a finite-volume CFD code. It is aimed to make investigation of the early flow transition with assessment of the flow response to radial pulsatile motion superimposed to the inner cylinder cross-section as an extension of a previous developed work in Oualli et al. [H. Oualli, A. Lalaoua, S. Hanchi, A. Bouabdallah, Eur. Phys. J. Appl. Phys. 61, 11102 (2013)] where a comparative controlling strategy is applied to the outer cylinder. The same basic system is considered with similar calculating parameters and procedure. In Oualli et al. [H. Oualli, A. Lalaoua, S. Hanchi, A. Bouabdallah, Eur. Phys. J. Appl. Phys. 61, 11102 (2013)], it is concluded that for the actuated outer cylinder and relatively to the non-controlled case, the critical Taylor number, Tac1, characterizing the first instability onset illustrated by the piled Taylor vortices along the gap, increases substantially to reach a growing rate of 70% when the deforming amplitude is ɛ = 15%. Interestingly, when this controlling strategy is applied to the inner cylinder cross-section with a slight modification of the actuating law, this tendency completely inverts and the critical Taylor number decreases sharply from Tac1 = 41.33 to Tac1 = 17.66 for ɛ = 5%, corresponding to a reduction rate of 57%. Fundamentally, this result is interesting and can be interpreted by prematurely triggering instabilities resulting in rapid development of flow turbulence. Practically, important applicative aspects can be met in several industry areas where substantial intensification of transport phenomena (mass, momentum and heat) is

  17. Oxygen-induced changes in electron-energy-loss spectra for Al, Be and Ni. [Al; Be; Ni

    SciTech Connect

    Madden, H.H.; Landers, R.; Kleiman, G.G. , 13081-970 Campinas, Sao Paulo, Brasil); Zehner, D.M. )

    1999-09-01

    Electron-energy-loss spectroscopy (EELS) data are presented to illustrate line shape changes that occur as a result of oxygen interaction with metal surfaces. The metals were aluminum, beryllium and nickel. Core-level EELS data were taken for excitations from Al(2p), Be(1s), Ni(3p/3s) and O(1s) levels to the conduction band (CB) density of states (DOS) of the materials. The primary beam energies for the spectra were 300, 450, 300, and 1135 eV, respectively. The data are presented in both the (as measured) first-derivative and the integral forms. The integral spectra were corrected for coherent background losses and analyzed for CB DOS information. These spectra were found to be in qualitative agreement with published experimental and theoretical studies of these materials. One peak in the spectra for Al oxide is analyzed for its correlation with excitonic screening of the Al(2p) core hole. Similar evidence for exciton formation is found in the Ni(3p) spectra for Ni oxide. Data are also presented showing oxygen-induced changes in the lower-loss-energy EELS curves that, in the pure metal, are dominated by plasmon-loss and interband-transition signals. Single-scattering loss profiles in the integral form of the data were calculated using a procedure of Tougaard and Chorkendorff [S. Tougaard and I. Chorkendorff, Phys. Rev. B. [bold 35], 6570 (1987)]. For all three oxides these profiles are dominated by a feature with a loss energy of around 20[endash]25 eV. Although this feature has been ascribed by other researchers as due to bulk plasmon losses in the oxide, an alternative explanation is that the feature is simply due to O(2s)-to-CB-level excitations. An even stronger feature is found at 7 eV loss energy for Ni oxide. Speculation is given as to its source. The line shapes in both the core-level and noncore-level spectra can also be used simply as [open quotes]fingerprints[close quotes] of the surface chemistry of the materials. Our data were taken using commercially

  18. Al 1s-2p Absorption Spectroscopy of Shock-Wave Heating and Compression in Laser-Driven Planar Foil

    SciTech Connect

    Sawada, H.; Regan, S.P.; Radha, P.B.; Epstein, R.; Li, D.; Goncharov, V.N.; Hu, S.X.; Meyerhofer, D.D.; Delettrez, J.A.; Jaanimagi, P.A.; Smalyuk, V.A.; Boehly, T.R.; Sangster, T.C.; Yaakobi, B.; Mancini, R.C.

    2009-05-19

    Time-resolved Al 1s-2p absorption spectroscopy is used to diagnose direct-drive, shock-wave heating and compression of planar targets having nearly Fermi-degenerate plasma conditions (Te ~ 10–40 eV, rho ~ 3–11 g/cm^3) on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. A planar plastic foil with a buried Al tracer layer was irradiated with peak intensities of 10^14–10^15 W/cm^2 and probed with the pseudocontinuum M-band emission from a point-source Sm backlighter in the range of 1.4–1.7 keV. The laser ablation process launches 10–70 Mbar shock waves into the CH/Al/CH target. The Al 1s-2p absorption spectra were analyzed using the atomic physic code PRISMSPECT to infer Te and rho in the Al layer, assuming uniform plasma conditions during shock-wave heating, and to determine when the heat front penetrated the Al layer. The drive foils were simulated with the one-dimensional hydrodynamics code LILAC using a flux-limited (f =0.06 and f =0.1) and nonlocal thermal-transport model [V. N. Goncharov et al., Phys. Plasmas 13, 012702 (2006)]. The predictions of simulated shock-wave heating and the timing of heat-front penetration are compared to the observations. The experimental results for a wide variety of laser-drive conditions and buried depths have shown that the LILAC predictions using f = 0.06 and the nonlocal model accurately model the shock-wave heating and timing of the heat-front penetration while the shock is transiting the target. The observed discrepancy between the measured and simulated shock-wave heating at late times of the drive can be explained by the reduced radiative heating due to lateral heat flow in the corona.

  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. 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.

  1. 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.

  2. 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.

  3. Supplement to the paper "Quadratic Sagnac effect — the influence of the gravitational potential of the Coriolis force on the phase difference between the arms of a rotating Michelson interferometer (an explanation of D C Miller's experimental results, 1921 - 1926)" (Usp. Fiz. Nauk 185 431 (2015) [Phys. Usp. 58 398 (2015)])

    NASA Astrophysics Data System (ADS)

    Malykin, G. B.; Pozdnyakova, V. I.

    2015-08-01

    The paper "Quadratic Sagnac effect — the influence of the gravitational potential of the Coriolis force on the phase difference between the arms of a rotating Michelson interferometer (an explanation of D C Miller's experimental results, 1921 - 1926)" (Usp. Fiz. Nauk 185 431 (2015) [Phys. Usp. 58 398 (2015)]) is amended and supplemented with information concerning earlier work on the influence of rotation on Michelson - Morley's nonzero results.

  4. The effect of Si in Al-alloy on electromigration performance in Al filled vias

    NASA Astrophysics Data System (ADS)

    Kageyama, Makiko; Hashimoto, Keiichi; Onoda, Hiroshi

    1998-01-01

    Electromigration performance of vias filled with Al-Si-Cu alloys on Ti glue layers was investigated in comparison with W-stud vias. In Al-Si-Cu filled vias, voids were formed at only a few locations in the test structure, while voids were formed at every via in W-stud via chains. It is supposed that Al moves through the Al-Si-Cu via during electromigration in spite of the existence of a glue layer at the via bottom. This phenomenon was observed only in the vias filled with Al-Si-Cu alloy. Al movement was prohibited in Al-Cu filled vias. In Al-Si-Cu filled vias, an Al-Ti-Si alloy was formed at the via bottom while Al3Ti was formed at Al-Cu filled vias. Al is speculated to move through this Al-Ti-Si alloy during electromigration.

  5. Secure Quantum Private Comparison of Equality Based on Asymmetric W State

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Jie; Liu, Chao; Wang, Hai-bin; Liu, Jing-Fa; Wang, Fang; Yuan, Xiao-Min

    2014-06-01

    Recently, Liu et al. (Opt. Commun. 284:3160, 2011) proposed a protocol for quantum private comparison of equality (QPCE) based on symmetric W state. However, Li et al. (Eur. Phys. J. D 66:110, 2012) pointed out that there is a flaw of information leak, and they proposed a new protocol based on EPR pairs. While examining these two protocols, we find that there exists a same flaw: the third party (TP) can know the comparison result. In this paper, through introducing and constructing a special class of asymmetric W state, a secure QPCE protocol based on this asymmetric W state is presented. Analysis shows the present protocol can not only effectively avoid the information leak found by Li et al., but also ensure TP would not get any information about the comparison result.

  6. New Particle Formation Events During 2013 in Hada Al Sham, Saudi-Arabia

    NASA Astrophysics Data System (ADS)

    Neitola, K.; Hyvärinen, A.; Lihavainen, H.; Alghamdi, M.; Hussein, T.; Khodeir, M.; Shehata, A.; Laaksonen, A. J.; Kulmala, M. T.

    2014-12-01

    clear growth, S is clear shrinkage, G + S is both growth and shrinkage and unclear is not clear in either way.ReferencesM. Dal Maso, et al. (2005). Bor. Env. Res., 10, 323-336.M. Kulmala, et al. (2006). Atmos. Chem. Phys., 6, 787-793. M. Kulmala, et al. (2013). Science, 336, 943-946.

  7. Emerging mechanisms of molecular pathology in ALS

    PubMed Central

    Peters, Owen M.; Ghasemi, Mehdi; Brown, Robert H.

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a devastating degenerative disease characterized by progressive loss of motor neurons in the motor cortex, brainstem, and spinal cord. Although defined as a motor disorder, ALS can arise concurrently with frontotemporal lobal dementia (FTLD). ALS begins focally but disseminates to cause paralysis and death. About 10% of ALS cases are caused by gene mutations, and more than 40 ALS-associated genes have been identified. While important questions about the biology of this disease remain unanswered, investigations of ALS genes have delineated pathogenic roles for (a) perturbations in protein stability and degradation, (b) altered homeostasis of critical RNA- and DNA-binding proteins, (c) impaired cytoskeleton function, and (d) non-neuronal cells as modifiers of the ALS phenotype. The rapidity of progress in ALS genetics and the subsequent acquisition of insights into the molecular biology of these genes provide grounds for optimism that meaningful therapies for ALS are attainable. PMID:25932674

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

    DOE PAGESBeta

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

    2016-06-14

    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

  9. 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.

  10. Determination of the structure factor of simple liquid metals from the pseudopotential theory and optimized random-phase approximation: Application to Al and Ga

    NASA Astrophysics Data System (ADS)

    Bretonnet, J. L.; Regnaut, C.

    1985-04-01

    We present the results of calculations of the static structure factor S(q) of liquid Al and Ga at the melting point. These calculations were motivated because many simple liquid metals exhibit structure anomalies taking the form of a shoulder on the main peak or even an asymmetry in the peak itself, while other liquid metals are correctly predicted by the standard models of liquid structure. Al and Ga have similar valence, electronic density, and size of their ionic radius; therefore, their pair potentials are somewhat similar. Despite this, their structure factors display most of the differences that can be observed among the variety of liquid metals. Starting from the Shaw optimized model potential [Phys. Rev. 174, 769 (1968)], a pair potential is constructed. A comparative examination of the electron-gas response function of Vashishta and Singwi [Phys. Rev. B 6, 875 (1972)] and of Ichimaru and Utsumi [Phys. Rev. B 24, 7385 (1981)] is carried out. Different depletion hole distributions are also used and full nonlocality is taken into account through effective masses. So S(q) is calculated by means of the optimized random-phase approximation. Particular attention is also devoted to the low-q region. By comparison with Monte Carlo computation, we show the limitation of various thermodynamic perturbation methods, such as the random-phase approximation or the soft-sphere model. The study of S(q) provides a stringent test of the model potential, where the electron-ion pseudopotential and the local-field correction are of prime importance, but where effective masses and depletion hole distribution may also have a role to play.

  11. Synthesis of Al-Al2O3 and Al-Aln Nanoparticle Composites Via Electric Explosion of Wires

    NASA Astrophysics Data System (ADS)

    Lerner, M. I.; Lozhkomoev, A. S.; Pervikov, A. V.; Bakina, O. V.

    2016-07-01

    Composite Al-Al2O3 and Al-AlN nanoparticles were synthesized via electric explosion of aluminum wires in an argon-oxygen gas mixture and in nitrogen. The parameters of electric explosion and gas medium affect the size and relative content of nitride and aluminum oxide in the nanoparticles. Processes of forming chemical compounds during aluminum oxidation at the contact surface between explosive products and gas and of nitrogen diffusions into the nanoparticles of the condensed phase are considered.

  12. Investigation of Wear Anisotropy in a Severely Deformed Al-Al3Ti Composite

    NASA Astrophysics Data System (ADS)

    El-Hadad, Shimaa; Sato, Hisashi; Watanabe, Yoshimi

    2012-09-01

    In the current investigation, Al-Al3Ti composite was processed by equal channel angular pressing (ECAP). ECAP was carried out using routes A and BC up to eight passes of deformation. It was observed that increasing the number of ECAP passes causes fragmentation of Al3Ti platelet particles and decreases their sizes compared to their original sizes in the undeformed Al-Al3Ti specimens. Moreover, the microstructure of route A-ECAPed Al-Al3Ti composite samples showed a strong alignment of the fragmented Al3Ti particles parallel to the pressing axis. On the other hand, ECAPed Al-Al3Ti alloy specimens by route BC have a relatively homogeneous distribution of Al3Ti particles. Because of the platelet Al3Ti particle fragmentation by ECAP, all the ECAPed specimens showed small anisotropy in their wear property in spite of this observed anisotropic microstructure induced by route A-ECAP.

  13. Investigation of Wear Anisotropy in a Severely Deformed Al-Al3Ti Composite

    NASA Astrophysics Data System (ADS)

    El-Hadad, Shimaa; Sato, Hisashi; Watanabe, Yoshimi

    2012-05-01

    In the current investigation, Al-Al3Ti composite was processed by equal channel angular pressing (ECAP). ECAP was carried out using routes A and BC up to eight passes of deformation. It was observed that increasing the number of ECAP passes causes fragmentation of Al3Ti platelet particles and decreases their sizes compared to their original sizes in the undeformed Al-Al3Ti specimens. Moreover, the microstructure of route A-ECAPed Al-Al3Ti composite samples showed a strong alignment of the fragmented Al3Ti particles parallel to the pressing axis. On the other hand, ECAPed Al-Al3Ti alloy specimens by route BC have a relatively homogeneous distribution of Al3Ti particles. Because of the platelet Al3Ti particle fragmentation by ECAP, all the ECAPed specimens showed small anisotropy in their wear property in spite of this observed anisotropic microstructure induced by route A-ECAP.

  14. 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.

  15. Quantum Criticality and Superconductivity in β-YbAlB4

    NASA Astrophysics Data System (ADS)

    Nakatsuji, Satoru

    2009-03-01

    Heavy fermion systems have provided a number of prototypical compounds to study unconventional superconductivity and non-Fermi-liquid (NFL) states. A long standing issue in the research of heavy fermion superconductivity in 4f intermetallics is the dramatically different behavior between the electron like Ce (4f^1) and hole like Yb (4f^13) compounds. While superconductivity has been found in a number of Ce based heavy fermion compounds, no superconductivity has been reported for the corresponding Yb systems. In this talk, I present our recent finding of the superconductivity in the new heavy fermion system β-YbAlB4 [1-3]. The superconducting transition temperature is 80 mK, and above it, the system exhibits pronounced NFL behavior in the transport and thermodynamic properties [2,3]. Furthermore, the magnetic field dependence of the NFL behavior indicates that the system is a rare example of a pure metal that displays quantum criticality at ambient pressure and under zero magnetic field. Using our latest results, we discuss the detailed properties of superconductivity and quantum criticality. This is the work performed in collaboration with K. Kuga, Y. Matsumoto, T. Tomita, Y. Machida, T. Tayama, T. Sakakibara, Y. Karaki, H. Ishimoto, S. Yonezawa, Y. Maeno, E. Pearson, G. G. Lonzarich, L.Balicas, H. Lee, and Z. Fisk. [4pt] [1] Robin T. Macaluso, Satoru Nakatsuji, Kentaro Kuga, Evan Lyle Thomas, Yo Machida, Yoshiteru Maeno, Zachary Fisk, and Julia Y. Chan, Chem. Mater. 19 1918 (2007). [0pt] [2] S. Nakatsuji, K.Kuga, Y. Machida, T. Tayama, T. Sakakibara, Y. Karaki, H. Ishimoto, S. Yonezawa, Y. Maeno, E. Pearson, G. G. Lonzarich, L.Balicas, H. Lee, and Z. Fisk, Nature Phys 4, 603-607 (2008). [0pt] [3] K. Kuga, Y. Karaki, Y. Matsumoto, Y. Machida, and S. Nakatsuji, Phys. Rev. Lett. 101, 137004 (2008).

  16. 77 FR 73732 - In the Matter of Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-11

    ... Matter of Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al-Jihad, aka The... al-Rafidayn, aka The Organization of al-Jihad's Base of Operations in Iraq, aka al-Qaida of Jihad in Iraq, aka al-Qaida in Iraq, aka al-Qaida in Mesopotamia, aka al-Qaida in the Land of the Two...

  17. The Al-Al3Ni Eutectic Reaction: Crystallography and Mechanism of Formation

    NASA Astrophysics Data System (ADS)

    Fan, Yangyang; Makhlouf, Makhlouf M.

    2015-09-01

    The characteristics of the Al-Al3Ni eutectic structure are examined with emphasis on its morphology and crystallography. Based on these examinations, the mechanism of formation of this technologically important eutectic is postulated. It is found that a thin shell of α-Al forms coherently around each Al3Ni fiber. The excellent thermal stability of the Al-Al3Ni eutectic may be attributed to the presence of this coherent layer.

  18. 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.

  19. Response to “Comment on ‘Motion of a helical vortex filament in superfluid {sup 4}He under the extrinsic form of the local induction approximation”’ [Phys. Fluids 26, 019101 (2014)

    SciTech Connect

    Van Gorder, Robert A.

    2014-01-15

    I agree with the authors regarding their comments on the Donnelly-Glaberson instability for such helical filaments as those obtained in my paper. I also find merit in their derivation of the quantum LIA (local induction approximation) in the manner of the LIA of Boffetta et al. However, I disagree with the primary criticisms of Hietala and Hänninen. In particular, though they suggest LIA and local nonlinear equation modes are not comparable since the former class of models contains superfluid friction parameters, note that since these parameters are small one may take them to zero and consider a qualitative comparison of the models (which is what was done in my paper). Second, while Hietala and Hänninen criticize certain assumptions made in my paper (and the paper of Shivamoggi where the model comes from) since the results break-down when Ak → ∞, note that in my paper I state that any deviations from the central axis along which the filament is aligned must be sufficiently bounded in variation. Therefore, it was already acknowledged that Ak(=|Φ{sub x}|) should be sufficiently bounded, precluding the Ak → ∞ case. I also show that, despite what Hietala and Hänninen claim, the dispersion relation obtained in my paper is consistent with LIA, where applicable. Finally, while Hietala and Hänninen claim that the dispersion parameter should be complex valued, I show that their dispersion relation is wrong, since it was derived incorrectly (they assume the complex modulus of the potential function is constant, yet then use this to obtain a potential function with non-constant modulus)

  20. Reply to Pachai et al.

    PubMed

    Harrison, William J; Bex, Peter J

    2016-05-01

    Peripheral vision is fundamentally limited by the spacing between objects. When asked to report a target's identity, observers make erroneous reports that sometimes match the identity of a nearby distractor and sometimes match a combination of target and distractor features. The classification of these errors has previously been used to support competing 'substitution' [1] or 'averaging' [2] models of the phenomenon known as 'visual crowding'. We recently proposed a single model in which both classes of error occur because observers make their reports by sampling from a biologically-plausible population of weighted responses within a region of space around the target [3]. It is critical to note that there is no probabilistic substitution or averaging process in our model; instead, we argue that neither substitution nor averaging occur, but that these are misclassifications of the distribution of reports that emerge when a population response distribution is sampled. This is a fundamentally different way of thinking about crowding, and on this basis we claim to have provided a mechanism unifying categorically distinct perceptual errors. Our goal was not to model all crowding phenomena, such as the release from crowding when target and flanks differ in color or depth [4]. Pachai et al.[5] have suggested that our model is not unifying because it inaccurately predicts perceptual performance for a particular stimulus. Although we agree that our model does not predict their data, this specific demonstration overlooks the critical aspect of the model: perceptual reports are drawn from a weighted population code. We show that Pachai et al.'s [5] own data actually provide evidence for the population code we have described [3], and we suggest a biologically-plausible analysis of their stimuli that provides a computational basis for their 'grouping' account of crowding. PMID:27166690

  1. Mechanical properties of submicron-grained TiAl alloys prepared by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Oehring, M.; Appel, F.; Pfullmann, Th.; Bormann, R.

    1995-02-01

    Ti-48 at. % Al powders of the metastable hexagonal-closed-packed solid solution with a grain size of 15 nm were prepared by mechanical alloying. The powders were consolidated to a density of greater than 99.5% by hot isostatic pressing (HIP) at 800 °C. After HIP the material exhibits a globular microstructure of the equilibrium phases α2 and γ with a mean grain size of 150 nm. Microhardness measurements show a Hall-Petch type [E. O. Hall, Proc. Phys. Soc. B 64, 747 (1951); N. J. Petch, J. Iron Steel Inst. 174, 25 (1953)] dependence on grain size. Room temperature compression tests reveal low ductility, but high fracture strengths ≥1800 MPa. On increasing the test temperature the yield strength drops sharply in the temperature range 600-800 °C to very low values. The results indicate that submicron-grained TiAl alloys can be deformed at much lower temperatures than coarse-grained material, making them suitable as precursors for net shaping, in particular if high deformation ratios are required.

  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. Everyday Life with ALS: A Practical Guide

    MedlinePlus

    ... course of ALS. ALS also will require some adaptations to your environment, both for safety and to ... the way, Chapter 6 will include information on adaptations for computer access. Though the chapter is called “ ...

  4. Benefits for Military Veterans with ALS

    MedlinePlus

    ... Chapters Certified Centers and Clinics Support Groups About ALS About Us Our Research In Your Community Advocate ... Veterans Resources for Military Veterans, Families & Survivors The ALS Association is working everyday to support people with ...

  5. Pressure dependence of the electronic structure of a [311] piezoelectric Ga0.85In0.15As/AlAs superlattice

    NASA Astrophysics Data System (ADS)

    Reparaz, J. S.; Muniz, L. R.; Goñi, A. R.; Alonso, M. I.; Rozas, G.; Fainstein, A.; Saravanan, S.; Vaccaro, P. O.

    2010-09-01

    We have studied the electronic subband structure of a piezoelectric [311] Ga0.85In0.15As/AlAs superlattice by means of high-hydrostatic pressure and excitation-power-dependent photoluminescence at 78 K. In particular, we unraveled the origin of two optical transitions at around 1.96 and 2 eV at ambient pressure, which were recently found to give rise to an unexpectedly strong resonant enhancement of the acoustic-phonon Raman scattering for such samples with permanent built-in piezoelectric fields [G. Rozas , Phys. Rev. B 77, 165314 (2008)10.1103/PhysRevB.77.165314]. Here we demonstrate that these transitions are doubly indirect, in real and reciprocal space, corresponding to radiative recombination processes between electrons at the X valleys of the AlAs barriers and heavy holes at the Γ point of the Brillouin zone but confined to the GaInAs quantum wells. In addition, the partial screening of the piezoelectric field induced by carrier photoexcitation under illumination becomes largely suppressed for pressures above 1.1 GPa due to conduction-band Γ-X crossover effects.

  6. Aluminium distribution in ZSM-5 revisited: The role of Al-Al interactions

    SciTech Connect

    Ruiz-Salvador, A. Rabdel; Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W.

    2013-02-15

    We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al-Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si{sub 94}Al{sub 2}O{sub 192} cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g., the T14 site), and the Al-Al interaction, which at this Si/Al maximises Al-Al distances in general agreement with Dempsey's rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al-Al distances. - Graphical abstract: Role of Al-Al interactions in high silica ZSM-5 is shown to be anisotropic in nature and not dependent solely on Coulombic interactions. Highlights: Black-Right-Pointing-Pointer Si-Al distribution in ZSM-5 is revisited, stressing the role of the Al-Al interaction. Black-Right-Pointing-Pointer Coulomb interactions are not the key factors controlling the Al siting. Black-Right-Pointing-Pointer Anisotropy of the framework is identified as a source of departure from Dempsey's rule.

  7. 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.

  8. Nonstoichiometry of Al-Zr intermetallic phases

    SciTech Connect

    Radmilovic, V.; Thomas, G.

    1994-06-01

    Nonstoichiometry of metastable cubic {beta}{prime} and equilibrium tetragonal {beta} Al-Zr intermetallic phases of the nominal composition Al{sub 3}Zr in Al-rich alloys has been extensively studied. It is proposed that the ``dark contrast`` of {beta}{prime} core in {beta}{prime}/{sigma}{prime} complex precipitates, in Al-Li-Zr based alloys, is caused by incorporation of Al and Li atoms into the {beta}{prime} phase on Zr sublattice sites, forming nonstoichiometric Al-Zr intermetallic phases, rather than by Li partitioning only. {beta}{prime} particles contain very small amounts of Zr, approximately 5 at.%, much less than the stoichiometric 25 at.% in the Al{sub 3}Zr metastable phase. These particles are, according to simulation of high resolution images, of the Al{sub 3}(Al{sub 0.4}Li{sub 0.4}Zr{sub 0.2}) type. Nonstoichiometric particles of average composition Al{sub 4}Zr and Al{sub 6}Zr are observed also in the binary Al-Zr alloy, even after annealing for several hours at 600{degree}C.

  9. Cyclic oxidation resistance of a reaction milled NiAl-AlN composite

    NASA Technical Reports Server (NTRS)

    Lowell, Carl E.; Barrett, Charles A.; Whittenberger, J. D.

    1990-01-01

    Based upon recent mechanical property tests a NiAl-AlN composite produced by cryomilling has very attractive high temperature strength. This paper focuses on the oxidation resistance of the NiAl-AlN composite at 1473 and 1573 K as compared to that of Ni-47Al-0.15Zr, one of the most oxidation resistant intermetallics. The results of cyclic oxidation tests show that the NiAl-AlN composite has excellent properties although not quite as good as those of Ni-47Al-0.15Zr. The onset of failure of the NiAl-AlN was unique in that it was not accompanied by a change in scale composition from alumina to less protective oxides. Failure in the composite appears to be related to the entrapment of AlN particles within the alumina scale.

  10. 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.

  11. 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.

  12. Parallel magnetic field-induced conductance fluctuations in GaAs/AlGaAs ballistic quantum dots.

    NASA Astrophysics Data System (ADS)

    Faniel, S.; Gustin, C.; Melinte, S.; Hackens, B.; Bayot, V.; Shayegan, M.

    2004-03-01

    We present magnetotransport measurements in ballistic quantum dots under a parallel magnetic field. The dots were fabricated on two different GaAs/AlGaAs quantum wells with thicknesses of 15 and and 45 nm and with one and two subbands occupied, respectively. The samples were patterned using e-beam lithography and wet etching. A Cr/Au electrostatic top gate was used in order to tune the width of the dot openings. The measurements were performed down to 300 mK with the magnetic field applied strictly parallel to the plane of the two-dimensional electron gas. For both dots, we observe universal conductance fluctuations and, in the case of the wide quantum well, a reduction of their amplitude at large magnetic field. We discuss these conductance fluctuations in terms of orbital effect(V.I. Fal'ko and T. Jungwirth, Phys Rev B 65), 081306 (2002) and magnetic subband depopulation.

  13. 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.

  14. A reply to Wang T, Shan L, Du L, Feng J, Xu Z, Staal WG, Jia F. Serum concentration of 25-hydroxyvitamin D in autism spectrum disorder: a systematic review and meta-analysis. Eur Child Adolesc Psychiatry. 2015; doi: 10.1007/s00787-015-0786-1.

    PubMed

    Fluegge, Keith

    2016-04-01

    The author of this correspondence has recently published findings of an ecological investigation wherein herbicide use was proposed as an instrumental variable that predicts healthcare utilization among subjects with severe ADHD impairment via individual exposure to nitrous oxide (N2O) emissions. Vitamin D deficiency, a possible risk factor for autism spectrum disorders (ASD) as discussed by Wang et al., may be a homeostatic response to increasing chronic environmental N2O exposures. The author explains how deficient and insufficient states of vitamin D may promote vagal withdrawal and tolerance to increasing opioid exposures in the environment and how these characteristics are particularly relevant in neurodevelopmental disorders, like ASD and ADHD. PMID:26662808

  15. 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

  16. Conduction electron spin resonance in the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds.

    PubMed

    Holanda, L M; Lesseux, G G; Magnavita, E T; Ribeiro, R A; Nakatsuji, S; Kuga, K; Fisk, Z; Oseroff, S B; Urbano, R R; Rettori, C; Pagliuso, P G

    2015-07-01

    β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb(3+) local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB4 possesses a previously known structural variant, namely the α-YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB4. For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB4. This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal. PMID:26045483

  17. Immunomodulatory drugs in AL amyloidosis.

    PubMed

    Jelinek, T; Kufova, Z; Hajek, R

    2016-03-01

    Immunoglobulin light chain amyloidosis (AL amyloidosis) is indeed a rare plasma cell disorder, yet the most common of the systemic amyloidoses. The choice of adequate treatment modality is complicated and depends dominantly on the risk stratification of these fragile patients. Immunomodulatory drugs (IMiDs) are currently used in newly diagnosed patients as well as in salvage therapy in relapsed/refractory patients. IMiDs have a pleiotropic effect on malignant cells and the exact mechanism of their action has been described recently. Thalidomide is the most ancient representative, effective but toxic. Lenalidomide seems to be more effective, nevertheless the toxicity remains high, especially in patients with renal insufficiency. Pomalidomide is the newest IMiD used in this indication with a good balance between efficacy and tolerable toxicity and represents the most promising compound. This review is focused on the evaluation of all three representatives of IMiDs and their roles in the treatment of this malignant disorder. PMID:26806146

  18. 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.

  19. 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.

  20. Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder

    NASA Astrophysics Data System (ADS)

    Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

    2013-12-01

    Reactive plasma spraying (RPS) is a promising technology for in situ formation of aluminum nitride (AlN) coatings. Recently, AlN-based coatings were fabricated by RPS of alumina (Al2O3) powder in N2/H2 thermal plasma. This study investigated the feasibility of RPS of a fine Al2O3/AlN mixture and the influence of the plasma gases (N2, H2) on the nitriding conversion, and coating microstructure and properties. Thick AlN/Al2O3 coatings with high nitride content were successfully fabricated. The coatings consist of h-AlN, c-AlN, Al5O6N, γ-Al2O3, and a small amount of α-Al2O3. Use of fine particles enhanced the nitriding conversion and the melting tendency by increasing the surface area. Furthermore, the AlN additive improved the AlN content in the coatings. Increasing the N2 gas flow rate improved the nitride content and complete crystal growth to the h-AlN phase, and enhanced the coating thickness. On the other hand, though the H2 gas is required for plasma nitriding of the Al2O3 particles, increasing its flow rate decreased the nitride content and the coating thickness. Remarkable influence of the plasma gases on the coating composition, microstructure, and properties was observed during RPS of the fine particles.

  1. Al/Al-N/AlN compositional gradient film synthesized by ion-beam assisted deposition method

    SciTech Connect

    Amamoto, Yoshiki; Uchiyama, Shingo; Watanabe, Yoshihisa; Nakamura, Yoshikazu

    1997-12-01

    Al/Al-N-AlN compositional gradient thin film was deposited on a Si(100) substrate at room temperature by ion-beam assisted deposition method, with a diminishing ion beam current from 1.4 to 0 mA at increments of 0.3 mA in order to gradually decrease the nitrogen to aluminum ratio at the substrate. The gradual Al and AlN variation in composition was shown by the change of the Al/N atomic ratio analyzed by the energy dispersive X-ray spectroscopy (EDX) and the X-ray photoelectron spectroscopy (XPS) in the cross section of the film. The formation of crystalline Al metal and AlN ceramic layer on the Si substrate was revealed by X-ray diffraction (XRD). The cross sectional image taken by high resolution transmission electron microscope (HRTEM) showed a nano-sized crystalline Al-N ceramic material and the flat interface between the Si substrate and the AlN film.

  2. Accumulation of Al in Root Mucilage of an Al-Resistant and an Al-Sensitive Cultivar of Wheat.

    PubMed Central

    Archambault, D. J.; Zhang, G.; Taylor, G. J.

    1996-01-01

    To estimate rates of Al accumulation within the symplasm, all apoplastic pools of Al need to be eliminated or accounted for. We have developed a revised kinetic protocol that allows us to estimate the contribution of mucilage-bound Al to total, nonexchangeable Al, and to eliminate the mucilage as an apoplastic pool of Al. By comparing the Al content of excised root tips (2 cm) of wheat (Triticum aestivum L.) with and without the removal of the mucilage (using a 10-min wash in 1 M NH4Cl), we found that Al bound to the mucilage accounted for approximately 25 to 35% of Al remaining after desorption in citric acid. The kinetics of Al uptake into mucilage were biphasic, with a rapid phase occurring in the first 30 min of uptake, followed by a linear phase occurring in the remainder of the experimental period (180 min). By adopting a step for removal of mucilage into our existing kinetic protocol, we have been able to isolate a linear phase of uptake with only a slight deviation from linearity in the first 5 min. Although we cannot unambiguously identify this phase of uptake as uptake into the symplasm, we believe this new protocol provides us with the most accurate quantitative estimate of symplastic Al yet available. PMID:12226458

  3. Twice-Hadamard-CNOT attack on Li et al.'s fault-tolerant quantum private comparison and the improved scheme

    NASA Astrophysics Data System (ADS)

    Ji, Sai; Wang, Fang; Liu, Wen-Jie; Yuan, Xiao-Min

    2015-04-01

    Recently, Li et al. presented a two-party quantum private comparison scheme using Greenberger-Horne-Zeilinger (GHZ) states and error-correcting code (ECC) [ Int. J. Theor. Phys. 52, 2818 (2013)], claiming it is fault-tolerant and could be performed in a non-ideal scenario. However, there exists a fatal loophole in their private comparison scheme under a special attack, namely the twice-Hadamard-CNOT attack. Specifically, a malicious party may intercept the other party's particles and execute Hadamard operations on the intercepted particles as well as on his or her own particles. Then, the malicious party could sequentially perform a controlled-NOT (CNOT) operation between intercepted particles and the auxiliary particles, as well as between his or her own particles and the auxiliary particles prepared in advance. By measuring the auxiliary particles, the secret input will be revealed to the malicious party without being detected. For resisting this special attack, a feasible improved scheme is proposed by introducing a permutation operator before the third party (TP) sends the particle sequences to each participant.

  4. Analysis of a laboratory experiment on neutron generation by discharges in the open atmosphere

    NASA Astrophysics Data System (ADS)

    Babich, L. P.

    2015-10-01

    A recently reported laboratory experiment with a high-voltage long discharge in the open atmosphere producing neutrons "…up to energies above 10 MeV…" [Agafonov et al., Phys. Rev. Lett. 111, 115003 (2013), 10.1103/PhysRevLett.111.115003] is critically analyzed. Known elementary processes, namely, nuclear synthesis 2H(2H,n )3He and 2H(14N,n )15O , photonuclear, electrodisintegration Anm(e-,n )mprescripts>m n -1 and opposite to the β-decay e-(p+,n ) νe reactions, as well as unconventional mechanisms and the hypothetical increase in the nuclear synthesis cross sections are not capable of accounting for the neutron generation under conditions of the experiment analyzed. In particular, total energy yields of reactions 2H(2H,n )3He and 2H(14N,n )15O are less than the claimed neutron energy above 10 MeV. Trustworthiness of the neutron measurements on the basis of the available study of the C-39 track detectors behavior carried out by Faccini et al. [Eur. Phys. J. C 74, 2894 (2014), 10.1140/epjc/s10052-014-2894-3] in connection with claimed observations of neutron emission in electrolytic cells is discussed. Real-time measurements of x-ray and neutron pulses by Agafonov et al. are commented on using the thorough study of the x-ray emissions by discharges under similar conditions [Kochkin et al., J. Phys. D: Appl. Phys. 45, 425202 (2012), 10.1088/0022-3727/45/42/425202].

  5. Triaxial Superdeformed Bands in ^163Tm

    NASA Astrophysics Data System (ADS)

    Pattabiraman, N. S.; Ghugre, S. S.; Garg, Umesh; Li, T.; Nayak, B. K.; Zhu, S.; Chakrawarthy, R. S.; Macchiavelli, A. O.; Janssens, R. V. F.

    2002-10-01

    Following the recent discovery of triaxial superdeformation bands in the Z = 71, 72 nuclei [1,2], we have investigated the Z = 69 nucleus ^163 Tm using the reaction ^130 Te( ^37 Cl, 4n) ^163 Tm with a beam energy of 170 MeV. Gamma-ray spectroscopy was performed using the Gammasphere array at LBNL. The data were sorted into a hypercube. The preliminary results have indicated two bands with δ E _γ 60 keV above the previously known 5286 keV, 49/2^- state. These bands appear to talk to one another. It may be recalled that evidence for wobbling motion has recently been reported in the isobaric nucleus ^163 Lu The detailed experimental results and comparisons with the neighboring nuclei will be presented. [1] H. Amro et al, Phys. Lett. B 506, 39(2001). [2] G. Schonwasser eet al., Eur. Phys. J. A13, 291(2002). [3] D. R. Jensen et al, Nucl. Phys. A 703, 3 (2002).

  6. In-plane electrical transport in n-type selectively doped GaSb/AlGaSb multiquantum wells

    NASA Astrophysics Data System (ADS)

    Ghezzi, C.; Cioce, B.; Magnanini, R.; Parisini, A.

    2001-11-01

    Results are reported regarding in-plane electrical transport in n-type selectively doped GaSb/AlGaSb multiquantum wells. In the samples, which were grown by molecular beam epitaxy, only the central regions of the Al0.40Ga0.60Sb barriers were Te doped. Low-field, low-temperature Hall measurements in the dark demonstrated the presence in the GaSb wells of a degenerate electron gas with nonzero occupancy only for the lowest miniband. A positive persistent photoconductivity effect, related to the DX character of the Te impurity, was also observed. This behavior enabled the μ electron mobility to be measured at T=10 K as a function of the nS sheet carrier density. Since the experimental data were consistent with a dominant role of the interface roughness scattering in the limiting of μ, the height, Δ, and the lateral size, Λ, of the interface roughness were determined from the analysis of the μ=μ(nS) dependence. Acceptable values of Δ were obtained, consistent with results of structural investigations in single quantum well samples of GaSb/Al0.40Ga0.60Sb [E. Kh. Mukhamedzhanov, C. Bocchi, S. Franchi, A. Baraldi, R. Magnanini, and L. Nasi, J. Appl. Phys. 87, 4234 (2000)].

  7. Beyond detection: biological physics informing progression and treatment of cancer Beyond detection: biological physics informing progression and treatment of cancer

    NASA Astrophysics Data System (ADS)

    Newman, T. J.; Thompson, A. M.

    2012-12-01

    The full text of the Preface is given in the PDF file. References [1] Kaur P et al 2012 Phys. Biol. 9 065001 [2] Lobikin M et al 2012 Phys. Biol. 9 065002 [3] Tanner K 2012 Phys. Biol. 9 065003 [4] Liu S V et al 2012 Phys. Biol. 9 065004 [5] Liao D et al 2012 Phys. Biol. 9 065005 [6] Liao D et al 2012 Phys. Biol. 9 065006 [7] Orlando P A et al 2012 Phys. Biol. 9 065007

  8. Fabrication of Nb/AlO x/Al/AlO x/Nb junctions for voltage standard applications

    NASA Astrophysics Data System (ADS)

    Maezawa, M.; Urano, C.; Kaneko, N.; Kiryu, S.

    2007-10-01

    We present an overdamped superconductor-insulator-normal-insulator-superconductor (SINIS) junction technology for ac voltage standard applications. Modifying our standard Nb-junction process, we developed a simple process for Nb/AlOx/Al/AlOx/Nb-junction circuits. A Josephson arbitrary waveform synthesizer device which consisted of a 100-SINIS-junction array embedded in a 50 Ω coplanar waveguide was fabricated and successfully tested.

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

    SciTech Connect

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

    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.

  10. 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

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

    PubMed

    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

  12. The Parr formula for the superheating field in a semi-infinite film

    NASA Astrophysics Data System (ADS)

    Del Castillo, Pierre

    2005-05-01

    Di Bartolo, Dolgert, and Dorsey [Phys. Rev. B 53, 5650-5660 (1996)] have constructed asymptotic matched solutions at order 2 for the half-space Ginzburg-Landau model in the weak-κ limit. These authors deduced a formal expansion for the superheating field hsh(κ) up to order 4, extending the de Gennes formula [Proceedings of the Eighth Latin American School of Physics, Caracas, 1966] and the two terms in Parr's formula [Z. Phys. B 25, 359-361 (1976)]. On the other hand, the present author [Eur. J. Appl. Math 13, 519-547 (2002)] obtained two terms in the lower bound for hsh(κ). In this paper, we prove rigorously that the second term of the expansion of hsh(κ) is of the order of O(κ1/2) and we get the Parr formula. We improve the upper bound obtained by Bolley and Helffer [Ann. Inst. Henri Poincaré, Anal. Non Linéaire 14, 597-613 (1997)] and we get κ(hsh(κ))2⩽2-3/2=15/32κ+O(κ1+ρ), ρ >0. The proof is based on new estimates for f', A, and A'. To achieve this, we are guided by the analysis of the properties of the approximate solution constructed previously in [Del Castillo, Math Modell. Numer. Anal. 36, 971-973 (2002); J. Math. Phys. 44, 2416-2450 (2003); Dolgert et al., Phys. Rev. B 53, 5650-5660 (1996)].

  13. 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.

  14. X-ray computed microtomography of sea ice - comment on "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow" by Bartels-Rausch et al. (2014)

    NASA Astrophysics Data System (ADS)

    Obbard, R. W.

    2015-07-01

    This comment addresses a statement made in "A review of air-ice chemical and physical interactions (AICI): liquids, quasi-liquids, and solids in snow" by Bartels-Rausch et al. (Atmos. Chem. Phys., 14, 1587-1633, doi:10.5194/acp-14-1587-2014, 2014). Here we rebut the assertion that X-ray computed microtomography of sea ice fails to reveal liquid brine inclusions by discussing the phases present at the analysis temperature.

  15. Laser fields at flat interfaces: II. Plasmon resonances in aluminium photoelectron spectra

    NASA Astrophysics Data System (ADS)

    Raşeev, G.

    2012-07-01

    Using the model derived in paper I [G. Raşeev, Eur. Phys. J. D 66, 167 (2012)], this work presents calculations of the photoelectron spectrum (PES) of low index aluminium surfaces in the 10-30 eV region. The laser is p or transverse magnetic linearly polarized incident on a flat structureless surface and its fields are modeled in I using the vector potential in the temporal gauge. This model uses a tensor and non-local isotropic (TNLI) susceptibility and solves the classical Ampère-Maxwell equation through the use of the vector potential from the electron density-coupled integro-differential equations (VPED-CIDE). The PE cross sections are the squares of the PE transition moments calculated using the VPED-CIDE vector potential function of the penetration coordinate. The PES is obtained in a one step model using either the Fermi golden rule or the Weisskopf-Wigner (WW) expressions. The WW cross section PES compares favorably with the experimental angle and energy resolved photoelectron yield (AERPY) spectrum of Levinson et al. [Phys. Rev. Lett. 43, 952 (1979)], Levinson and Plummer [Phys. Rev. B 24, 628 (1981)] for Al(001) and of Barman et al. [Phys. Rev. B 58, R4285 (1998)], Barman [Curr. Sci. 88, 54 (2005)] for Al(111) surfaces. As in the experiment, our theoretical AERPY displays the multipole surface plasmon resonance at 11.32/12.75 eV for Al(001)/Al(111), mainly due to the surface contribution |⟨ψf|p·A|ψi⟩|2, the bulk plasmon minimum at 15 eV and the two single particle excitation resonances at about 16 and 22 eV. The nature of the plasmon resonances of the PES is analyzed using the reflectance, the electron density induced by the laser and Feibelman's parameter d⊥ all introduced in paper I.

  16. 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.

  17. Effects of Al Contents on Carburization Behavior and Corrosion Resistance of TiAl Alloys

    NASA Astrophysics Data System (ADS)

    Liao, Cui Jiao; He, Yue Hui; Ming, Xing Zu

    2015-10-01

    TiAl alloys with Al contents of 30.7, 37, 46.5, and 54.2 at.% were carburized. Corrosion resistance of the untreated and the carburized TiAl alloys was comparatively analyzed. The phase and microstructure of the carburized TiAl alloys were studied by x-ray diffraction and scanning electron microscopy, respectively. Electrochemical corrosion behavior of the untreated and the carburized TiAl alloys was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Experimental results indicate that different Al contents bring about distinct microstructure of the carburized layers. The lower Al content leads to the formation of the thicker binary carbides and the thinner Ti2AlC phase. Additionally, the lower Al content leads to higher corrosion resistance in the untreated and the carburized states.

  18. 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

  19. Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites

    NASA Technical Reports Server (NTRS)

    Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

    1995-01-01

    The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

  20. A New Phase in ALS Research.

    PubMed

    Chong, P Andrew; Forman-Kay, Julie D

    2016-09-01

    In this issue of Structure, Conicella et al. (2016) present evidence that the low complexity C-terminal region of TDP-43 undergoes liquid-liquid phase separation. ALS-associated mutations alter this phase separation process, providing a possible mechanism for the pathology caused by these TDP-43 mutations. The work is strongly supportive of toxic loss of RNA processing function in ALS. PMID:27602988

  1. Memory deficits and retrieval processes in ALS.

    PubMed

    Mantovan, M C; Baggio, L; Dalla Barba, G; Smith, P; Pegoraro, E; Soraru', G; Bonometto, P; Angelini, C

    2003-05-01

    Subtle neuropsychological deficits have been described in patients affected by amyotrophic lateral sclerosis (ALS) without dementia. Overall, selective impairment in memory function has been reported, but the source of memory impairment in ALS has yet to be defined. We performed neuropsychological screening in 20 ALS patients. Semantic encoding and post-encoding cue effects on the retrieval of word lists were investigated in the ALS patients and normal controls. Severity of memory impairment was correlated to cerebral blood perfusion detected by single photon emission computed tomography (SPECT). ALS patients showed moderate impairments in frontal and memory tests. Short-term memory was normal, while serial position retrieval of word lists with normal recency effect but poor primacy effect showed long-term memory deficit. ALS patients performed better in cued encoding than in cued post-encoding recall condition. In the cued post-encoding condition, the primacy effect in word list recall improved significantly in controls, but not in ALS patients, as compared with both the free recall and cued encoding conditions. SPECT hypoperfusion was observed in frontal and temporal areas in ALS patients. ALS patients showed a long-term memory deficit which did not improve in cued post-encoding condition as it does for controls. We hypothesize abnormal retrieval processes related to frontal lobe dysfunction which entails difficulties in generating stable long-memory traces at encoding. PMID:12752394

  2. 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.

  3. Al-doped ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Kadam, Pratibha; Agashe, Chitra; Mahamuni, Shailaja

    2008-11-01

    Al3+-doped ZnO nanocrystals were differently obtained by wet chemical and an electrochemical route. An increase in forbidden gap due to change in crystal size and also due to Al3+ doping in ZnO is critically analyzed. The Moss-Burstein type shift in Al3+-doped ZnO nanocrystals provides an evidence of successful Al3+ doping in ZnO nanocrystals. The possibility of varying the carrier concentration in ZnO nanocrystals is the indirect implication of the present investigations.

  4. Genetics of Familial and Sporadic ALS

    ClinicalTrials.gov

    2016-03-21

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

  5. 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.

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

    SciTech Connect

    Jiang, Y; He, Y H; Zou, J; Huang, B; Liu, C

    2008-01-01

    PorousTi Alalloys 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 porousTi Alalloys can have three crystalline phases (i.e., 2-Ti3Al, -TiAl, and TiAl3) when using different compositions. The fundamental reasons behind these phenomena have been explored.

  7. Response to Signorovitch et al.

    PubMed

    Flot, Jean-François; Debortoli, Nicolas; Hallet, Bernard; Van Doninck, Karine

    2016-08-22

    Signorovitch et al.[1] comment that an Oenothera-like meiosis [2] could produce a pattern similar to what we observed in our study of natural isolates of the bdelloid rotifer Adineta vaga, which we attributed to horizontal gene transfers (HGTs) [3]. Indeed, our HGT hypothesis appears at first sight difficult to conciliate with their observation of a congruent pattern of allele sharing at four large loci possibly located on different chromosomes [4]. However, one might imagine conditions under which massive horizontal gene transfer between bdelloid individuals could produce such a pattern, notably if the individuals involved had previously lost most of their heterozygosity because of their exposure to frequent desiccation (which produces DNA double-strand breaks [5]). In the published A. vaga genome the loss of heterozygosity due to large-scale gene conversion events or break-induced replication covers only about 10% of the genome [6], but this percentage may be much higher in environmental isolates that often experience dessication. Besides, if an Oenothera-like mode of meiosis occurs in bdelloids frequently enough to be detected in a single sampling of 29 individuals (as in [4]), one would expect males and meiosis to be observed at least occasionally, and instances of congruent allele sharing across loci should turn up frequently in genetic surveys. This was not the case in [3]: among the 82 A. vaga individuals sequenced for four nuclear markers, no trio of individuals presented congruent patterns of shared sequences at different loci. For these reasons, and in the absence of any direct evidence for an Oenothera-like meiosis in bdelloids, we still consider inter-bdelloid HGTs a more parsimonious explanation for our results. PMID:27554651

  8. 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.

  9. 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

  10. 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

    2016-01-01

    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

  11. Phase diagram of LaVO3 under epitaxial strain: Implications for thin films grown on SrTiO3 and LaAlO3 substrates

    NASA Astrophysics Data System (ADS)

    Weng, Hongming; Terakura, Kiyoyuki

    2010-09-01

    Various exotic phenomena have been observed in epitaxially grown films and superlattices of transition-metal oxides. In these systems, not only the interface properties but also the strain-induced modification in the bulk properties play important roles. With the recent experimental activities [Y. Hotta, T. Susaki, and H. Y. Hwang, Phys. Rev. Lett. 99, 236805 (2007)10.1103/PhysRevLett.99.236805] in mind, we have studied the epitaxial strain effects on the electronic structure of Mott insulator LaVO3 . The present work is based on the calculations using density-functional theory supplemented by adding local Coulomb repulsion U for Vd orbitals. The range of strain studied here extends from c/a=0.98 (bulk LaVO3 case) to c/a=1.107 ( LaAlO3 substrate case). In this range of the strain, we have found the following three different antiferromagnetic spin-ordering (SO) phases. For 0.981.095 , G -type SO with ferromagnetic OO becomes the ground state. This range includes the case of LaAlO3 substrate. The implications of these results with regard to the experimental data for thin films of LaVO3 on SrTiO3 and LaAlO3 substrates will be described. Detailed discussion is given on the mechanisms of stabilizing particular combination of SO and OO in each of three phases.

  12. 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.

  13. 76 FR 18783 - United States et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-05

    ... Antitrust Division United States et al. v. Dean Foods Company; Proposed Final Judgment, Stipulation and... of America, et al. v. Dean Foods Company, Civil Action No. 2:10-cv-00059 (JPS). On January 22, 2010, the United States and its co-plaintiffs filed a Complaint alleging that Dean Foods...

  14. 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…

  15. 75 FR 62858 - United States, et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-13

    ... Antitrust Division United States, et al. v. American Express Company, et al.; Proposed Final Judgment and... been filed with the United States District Court for the Eastern District of New York in United States..., 2010, the United States and seven States filed a Complaint alleging that certain rules, policies,...

  16. 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

  17. Characteristics of heat resistant alloys Ti10Nb45Al and Ti18Nb48Al

    SciTech Connect

    Weijun Zhang; Guoliang Chen; Yandong Wang; Zuqing Sun )

    1993-05-01

    Based on a systematic study of the ternary Ti-Nb-Al system, two attractive heat resistant alloys, Ti10Nb45Al and Ti18Nb48Al, were developed, and the characteristics of these alloys were discussed: (1) After annealing at 1,200 C for 240 h and furnace cooling to room temperature, the Ti10Nb45Al alloy exhibits an [alpha][sub 2] + [gamma] lamellar microstructure, and the Ti18Nb48Al alloy shows a plate-like structure consisting of [alpha][sub 2], [gamma] and [gamma][sub 1] phases. (2) The specific strengths of Ti10Nb45Al and Ti18Nb48Al are much higher than TiAl and superalloys in the temperature range of 800 [approximately] 1,100 C. The compressive yield strengths of these alloys are on the order of 700 MPa at 800 C and 350 MPa at 1,100 C. The density of these alloys is about 4.3 g/cm[sup 3]. (3) The annealed Ti10Nb45Al and Ti18Nb48Al exhibit some ductility at room temperature, with the compressive elongation on the order of 12% and the fracture toughness as high as 16 MPa[radical]m. The ductile-brittle transformation temperatures for Ti10Nb45Al and Ti18Nb48Al are 650 C and 750 C, respectively. (4) The parabolic constant K[sub p] for oxidation of Ti10Nb45Al and Ti18Nb48Al are 0.88 and 0.29 mg[sup 2]cm[sup [minus]4]h[sup [minus]1] respectively, which are two orders of magnitude lower than that of TiAl and Ti[sub 3]Al alloys.

  18. Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys

    NASA Astrophysics Data System (ADS)

    Knipling, Keith E.; Dunand, David C.; Seidman, David N.

    2007-10-01

    Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375 °C or 425 °C. This is due to the absence of Al3Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al3Zr (L12) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in α-Al is much greater than that of Zr in α-Al; and (2) the relatively small liquid solubility of Ti in α-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al3Ti (L12) with α-Al is also larger than that of Al3Zr (L12), further hindering nucleation of Al3Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al3Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al3Ti precipitation and the presence of Al3Zr precipitation.

  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. 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

  2. Al-Akhawayni's description of pulmonary circulation.

    PubMed

    Yarmohammadi, Hassan; Dalfardi, Behnam; Rezaian, Jafar; Ghanizadeh, Ahmad

    2013-10-01

    Since antiquity, heart function and the mechanism of blood circulation within the human body have been the focus of attention of scientists from different parts of the world. Over the passage of time, the theories and works of these scientists have resulted in the achievement of today's knowledge of circulation. The medieval Persian scholar, Al-Akhawayni Bukhari (?-983AD), is among the physicians who investigated both the anatomy and the physiology of the human body. Al-Akhawayni describes the mechanism of pulmonary circulation in his only extant book, "Hidayat al-Muta`llemin fi al-Tibb" (A Scholar's Guide to Medicine) with which he made a contribution to the development of knowledge regarding this mechanism in the medicine of the Islamic world. In this paper, Al-Akhawayni's viewpoints on anatomy and the function of the heart, its related vessels, and also pulmonary circulation will be briefly discussed. PMID:23890868

  3. Opportunities for improving therapy development in ALS.

    PubMed

    Bruijn, Lucie; Cudkowicz, Merit

    2014-06-01

    In May 2013, The ALS Association and The Northeast ALS Consortium (NEALS) convened a meeting of stakeholders for a round-table discussion of ways to improve therapy development in ALS. The following overview summarizes issues raised and potential new directions discussed at the meeting. We recommend that future phase II clinical trials in ALS proceed when the proposed treatment is directed at targets that are likely to be involved in ALS pathogenesis in a defined subgroup of patients, and be accompanied by one or more biomarkers to track both clinical progression and pharmacodynamic engagement of the target. Innovations in trial structure and design, and greater involvement of patient advocates, may also improve trials. PMID:24472060

  4. AL(0) in municipal waste incinerator ash

    NASA Astrophysics Data System (ADS)

    Stipp, S. L.; Ronsbo, J. G.; Zunic, T. B.; Christensen, T. H.

    2003-04-01

    Disposal of municipal waste is a challenge to society. Waste volume is substantially decreased by incineration but residual ash usually contains a number of toxic components which must be immobilised to insure environmental protection. One element, chromium, is mobile and toxic in its oxidised state as Cr(VI) but it can be reduced to Cr(III) and immobilised. Reduction can be promoted by ash treatment with Fe(0) or Fe(II), but recent evidence shows that at least some Cr(VI) is reduced spontaneously in the ash. Aspects of ash behaviour suggest metallic aluminium as the reducing agent, but no direct evidence of Al(0) has been found until now. We examined filter ash from an energy-producing, municipal-waste incinerator (Vest-forbrænding) near Copenhagen. X-ray diffraction (XRD) identified expected salts of Na, K and Ca such as halite, sylvite, calcite, anhydrite and gypsum as well as quartz, feldspar and some hematite. Wave-dispersive electron microprobe produced elemen-tal maps of the ash; Al-rich areas were analysed quantitatively by comparison with standards. We identified metallic Al particles, averaging 50 to 100 micrometers in di-ameter, often with a fractured, glassy border of aluminum oxide. The particles were porous, explaining fast Cr(VI) reduction and they contained thin exsolution lamellae of Al-alloys of Pb and Cu or Mn, Fe and Ag, which provide clues of the Al(0) origin in the waste. Sometimes Al(0) occurred inside glassy globes of Al2O3. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) proved that surface Al concentrations on ash particles were below detection, confirming reactivity of the Al(0) bulk. The persistence of reduced Al through the highly oxidising combustion procedure comes as a surprise and is a benefit in the immobilisation of Cr(VI) from municipal-waste incineration residues.

  5. Al 1s-2p absorption spectroscopy of shock-wave heating and compression in laser-driven planar foil

    SciTech Connect

    Sawada, H.; Regan, S. P.; Radha, P. B.; Epstein, R.; Li, D.; Goncharov, V. N.; Hu, S. X.; Meyerhofer, D. D.; Delettrez, J. A.; Jaanimagi, P. A.; Smalyuk, V. A.; Boehly, T. R.; Sangster, T. C.; Yaakobi, B.; Mancini, R. C.

    2009-05-15

    Time-resolved Al 1s-2p absorption spectroscopy is used to diagnose direct-drive, shock-wave heating and compression of planar targets having nearly Fermi-degenerate plasma conditions (T{sub e}{approx}10-40 eV, {rho}{approx}3-11 g/cm{sup 3}) on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. A planar plastic foil with a buried Al tracer layer was irradiated with peak intensities of 10{sup 14}-10{sup 15} W/cm{sup 2} and probed with the pseudocontinuum M-band emission from a point-source Sm backlighter in the range of 1.4-1.7 keV. The laser ablation process launches 10-70 Mbar shock waves into the CH/Al/CH target. The Al 1s-2p absorption spectra were analyzed using the atomic physic code PRISMSPECT to infer T{sub e} and {rho} in the Al layer, assuming uniform plasma conditions during shock-wave heating, and to determine when the heat front penetrated the Al layer. The drive foils were simulated with the one-dimensional hydrodynamics code LILAC using a flux-limited (f=0.06 and f=0.1) and nonlocal thermal-transport model [V. N. Goncharov et al., Phys. Plasmas 13, 012702 (2006)]. The predictions of simulated shock-wave heating and the timing of heat-front penetration are compared to the observations. The experimental results for a wide variety of laser-drive conditions and buried depths have shown that the LILAC predictions using f=0.06 and the nonlocal model accurately model the shock-wave heating and timing of the heat-front penetration while the shock is transiting the target. The observed discrepancy between the measured and simulated shock-wave heating at late times of the drive can be explained by the reduced radiative heating due to lateral heat flow in the corona.

  6. Osmotic self-propulsion of slender particles

    NASA Astrophysics Data System (ADS)

    Schnitzer, Ory; Yariv, Ehud

    2015-03-01

    We consider self-diffusiophoresis of axisymmetric particles using the continuum description of Golestanian et al. ["Designing phoretic micro-and nano-swimmers," New J. Phys. 9, 126 (2007)], where the chemical reaction at the particle boundary is modelled by a prescribed distribution of solute absorption and the interaction of solute molecules with that boundary is represented by diffusio-osmotic slip. With a view towards modelling of needle-like particle shapes, commonly employed in experiments, the self-propulsion problem is analyzed using slender-body theory. For a particle of length 2L, whose boundary is specified by the axial distribution κ(z) of cross-sectional radius, we obtain the approximation - /μ 2 D L ∫- L L j ( z ) /d κ ( z ) d z d z for the particle velocity, wherein j(z) is the solute-flux distribution, μ the diffusio-osmotic slip coefficient, and D the solute diffusivity. This approximation can accommodate discontinuous flux distributions, which are commonly used for describing bimetallic particles; it agrees strikingly well with the numerical calculations of Popescu et al. ["Phoretic motion of spheroidal particles due to self-generated solute gradients," Eur. Phys. J. E: Soft Matter Biol. Phys. 31, 351-367 (2010)], performed for spheroidal particles.

  7. Recoil Separators for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Blackmon, J. C.

    2004-10-01

    Hydrogen and helium capture reactions are important in many astrophysical environments. Measurements in inverse kinematics using recoil separators have demonstrated a particularly sensitive technique for studying low-yield capture reactions.(M. S. Smith, C. E. Rolfs, and C. A. Barnes, Nucl. Instrum. Meth. Phys. Res. A306) (1991) 233. This approach allows a low background rate to be achieved with a high detection efficiency (about 50%) for the particles of interest using a device with only modest acceptance. Recoil separators using a variety of ion-optic configurations have been installed at numerous accelerator facilities in the past decade and have been used to measure, for example, alpha capture reactions using stable beams(D. Rogalla et al.), Eur. Phys. J. 6 (1999) 471. and proton capture reactions using radioactive ion beams.(S. Bishop et al.), Phys. Rev. Lett. 90 (2003) 162501. Measurements in inverse kinematics are the only viable means for studying reactions on short-lived nuclei that are crucial for understanding stellar explosions, and a recoil separator optimized for the measurement of capture reactions with radioactive ion beams figures prominently into the design of the low energy experimental area at the Rare Isotope Accelerator (RIA). The operational requirements for such a device will be outlined, and recoil separator designs and characteristics will be presented.

  8. Duality and Stationary Distributions of the "Immediate Exchange Model" and Its Generalizations

    NASA Astrophysics Data System (ADS)

    van Ginkel, Bart; Redig, Frank; Sau, Federico

    2016-04-01

    We study the "Immediate Exchange Model", a wealth distribution model introduced in Heinsalu and Patriarca (Eur Phys J B 87:170, 2014). We prove that the model has a discrete dual, where the duality functions are natural polynomials associated to the Gamma distribution with shape parameter 2 and are exactly those connecting the Brownian Energy Process (with parameter 2) and the corresponding Symmetric Inclusion Process in Carinci et al. (J Stat Phys 152:657-697, 2013) and Giardinà et al. (J Stat Phys 135(1):25-55, 2009). As a consequence, we recover invariance of products of Gamma distributions with shape parameter 2, and obtain ergodicity results. Next we show similar properties for a more general model, where the exchange fraction is Beta(s, t) distributed, and product measures with text{ Gamma }(s+t) marginals are invariant. We also show that the discrete dual model itself is self-dual and has the original continuous model as its scaling limit. We show that the self-duality is linked with an underlying SU(1, 1) symmetry, reminiscent of the one found before for the Symmetric Inclusion Process and related processes.

  9. Anomalous Diffusion in Low-temperature-grown AlAs/GaAs Heterostructures

    NASA Astrophysics Data System (ADS)

    Lahiri, I.; Chang, J. C. P.; Woodall, J. M.; Melloch, M. R.; Nolte, D. D.

    1996-03-01

    The interdiffusion of heterojunctions can be detrimental or beneficial for applications. Low-temperature-grown (LTG) GaAs which incorporates excess arsenic has attracted attention as a significant marketable new material system. The recent discovery(I. Lahiri, D. D. Nolte, E. S. Harmon, M. R. Melloch and J. M. Woodall, Appl. Phys. Lett. 66), 2519 (1995) of simultaneous ultrafast lifetimes and sharp excitonic transitions in AlAs/GaAs quantum wells grown at low substrate temperatures has made LTG MQWs an attractive candidate for applications. Excess arsenic in these materials provides a mechanism for enhanced and nonequilibrium interdiffusion. We have measured anomalously low effective migration enthalpies as small as 0.32 eV. This value is much smaller than physically recognized mechanisms, such as the migration enthalpy of 1.7 eV attributed to Ga vacancy diffusion. By performing isochronal and isothermal anneals we have recovered a migration enthalpy consistent with gallium vacancy diffusion, but with a time-dependent diffusion coefficient expected to be caused by the thermal annealing of the vacancies.

  10. A multicharge ion source (Supernanogan) for the OLIS facility at ISAC/TRIUMF

    SciTech Connect

    Jayamanna, K.; Wight, G.; Gallop, D.; Dube, R.; Jovicic, V.; Laforge, C.; Marchetto, M.; Leross, M.; Louie, D.; Laplante, R.; Laxdal, R.; McDonald, M.; Wiebe, G. J.; Wang, V.; Yan, F.

    2010-02-15

    The Off-Line Ion Source (OLIS) [K. Jayamanna, D. Yuan, T. Kuo, M. MacDonald, P. Schmor, and G. Dutto, Rev. Sci. Instrum. 67, 1061 (1996); K. Jayamanna, Rev. Sci. Instrum. 79, 02711 (2008)] facility consists of a high voltage terminal containing a microwave cusp ion source, either a surface ion source or a hybrid surface-arc discharge ion source [K. Jayamanna and C. Vockenhuber, Rev. Sci. Instrum. 79, 02C712 (2008)], and an electrostatic switch that allows the selection of any one of the sources without mechanical intervention. These sources provide a variety of +1 beams up to mass 30 for Isotope Separator and ACcelerator (ISAC) [R. E. Laxdal, Nucl. Instrum. Methods Phys. Res. B 204, 400 (2003)] experiments, commissioning the accelerators, setting up the radioactive experiments, and for tuning the beam lines. The radio frequency quadrupole (RFQ) [M. Marchetto, Z. T. Ang, K. Jayamanna, R. E. Laxdal, A. Mitra, and V. Zvyagintsev, Eur. Phys. J. Spec. Top. 150, 241 (2005)] injector accelerator is a constant velocity machine designed to accept only 2 keV/u and the source extraction energy is limited to 60 kV. Further stripping is then needed downstream of the RFQ to inject the beam into the drift tube linac [M. Marchetto, Z. T. Ang, K. Jayamanna, R. E. Laxdal, A. Mitra, and V. Zvyagintsev, Eur. Phys. J. Spec. Top. 150, 241 (2005)] accelerator that requires A/q up to 6. Base on this constraints a multicharge ion source capable to deliver beams above mass 30 with A/q up to 6 was needed in order to reach full capability of the ISAC facility. A Supernanogan [C. Bieth et al., Nucleonika 48, S93 (2003)] multicharge ion source was then purchased from Pantechnik and was installed in the OLIS terminal. Commissioning and performance of the Supernanogan with some results such as emittance dependence of the charge states as well as charge state efficiencies are presented.

  11. A multicharge ion source (Supernanogan) for the OLIS facility at ISAC/TRIUMFa)

    NASA Astrophysics Data System (ADS)

    Jayamanna, K.; Wight, G.; Gallop, D.; Dube, R.; Jovicic, V.; Laforge, C.; Marchetto, M.; Leross, M.; Louie, D.; Laplante, R.; Laxdal, R.; McDonald, M.; Wiebe, G. J.; Wang, V.; Yan, F.

    2010-02-01

    The Off-Line Ion Source (OLIS) [K. Jayamanna, D. Yuan, T. Kuo, M. MacDonald, P. Schmor, and G. Dutto, Rev. Sci. Instrum. 67, 1061 (1996); K. Jayamanna, Rev. Sci. Instrum. 79, 02711 (2008)] facility consists of a high voltage terminal containing a microwave cusp ion source, either a surface ion source or a hybrid surface-arc discharge ion source [K. Jayamanna and C. Vockenhuber, Rev. Sci. Instrum. 79, 02C712 (2008)], and an electrostatic switch that allows the selection of any one of the sources without mechanical intervention. These sources provide a variety of +1 beams up to mass 30 for Isotope Separator and ACcelerator (ISAC) [R. E. Laxdal, Nucl. Instrum. Methods Phys. Res. B 204, 400 (2003)] experiments, commissioning the accelerators, setting up the radioactive experiments, and for tuning the beam lines. The radio frequency quadrupole (RFQ) [M. Marchetto, Z. T. Ang, K. Jayamanna, R. E. Laxdal, A. Mitra, and V. Zvyagintsev, Eur. Phys. J. Spec. Top. 150, 241 (2005)] injector accelerator is a constant velocity machine designed to accept only 2 keV/u and the source extraction energy is limited to 60 kV. Further stripping is then needed downstream of the RFQ to inject the beam into the drift tube linac [M. Marchetto, Z. T. Ang, K. Jayamanna, R. E. Laxdal, A. Mitra, and V. Zvyagintsev, Eur. Phys. J. Spec. Top. 150, 241 (2005)] accelerator that requires A/q up to 6. Base on this constraints a multicharge ion source capable to deliver beams above mass 30 with A/q up to 6 was needed in order to reach full capability of the ISAC facility. A Supernanogan [C. Bieth et al., Nucleonika 48, S93 (2003)] multicharge ion source was then purchased from Pantechnik and was installed in the OLIS terminal. Commissioning and performance of the Supernanogan with some results such as emittance dependence of the charge states as well as charge state efficiencies are presented.

  12. Preface: phys. stat. sol. (c) 1/7

    NASA Astrophysics Data System (ADS)

    Cheikhrouhou, Abdelwaheb

    2004-05-01

    The Third International Conference on Magnetic and Superconducting Materials (MSM03) belongs to a series of conferences, held biannually, aiming at providing a forum to the scientists in the magnetic and superconducting materials areas over the world.The first conference of the series (MSM99) was held in Iran with the proceedings published by World Scientific in 2000, and the second conference (MSM01) was held in Jordan with the proceedings published in Physica B 321 (2002).MSM03 was organized by the Materials Physics Laboratory, Sfax University (Laboratoire de Physique des Matériaux de la Faculté des Sciences de Sfax), with many domestic and international supporting institutions. It was held in Monastir (Tunisia), 1-4 September 2003, with over 150 participants and keynote lecturers attending from the following countries: Algeria, Austria, China, Czech Republic, Egypt, France, Germany, Hungary, Iran, Italy, Japan, Jordan, Morocco, Netherlands, Pakistan, Poland, Russia, Spain, Sudan, Sultanate of Oman, Taiwan, Tunisia, United Kingdom and United States of America.Altogether, about 170 papers on a variety of subjects relevant to the topic of the conference were presented, out of which 42 were keynote lectures. The submissions were peer-reviewed, and ultimately 115 articles were selected for publication in this journal. However, it must be noted that 13 of 39 keynote speakers did not submit their manuscripts for publication. Invited and other speakers were distinguished members of the international scientific community who are interested in pure sciences and materials research, and involved in the fabrication, characterization and investigation of the physical properties of magnetic and superconducting materials. High-caliber scientists attended the conference contributing to its success and the event resulted in new international relationships in research and cooperation. The Chairman of the Organizing Committee was Professor Abdelwaheb Cheikhrouhou, Materials Physics Laboratory, Sciences Faculty of Sfax (Tunisia) and the Co-Chairmen were Professor Sami Mahmood, Dean of Sciences at Yarmouk University (Jordan) and Professor Mohamed Akhavan from the Sharif University of Technology (Iran). The four-day conference consisted of several oral and poster sessions, followed by social programs in the evenings. The success of the event could be measured during the closing session on the last day, when several delegates emphasized the high-quality science that had been evident at the conference. A post conference three-day tour to the south of Tunisia (Matmata, Douz City: the gate of desert and the mountains oasis: Tamerza, Mides and Chebika) was also arranged. The conference was generously sponsored by: - The Tunisian Ministry of High Education, Scientific Research and Technology - The Tunisian Secretary of State for Scientific Research and Technology - The Tunisian National Office of Tourism - The Abdus Salam International Centre for Theoretical Physics (ICTP) - French Institute for Cooperation in Tunisia - Tunisian-Italian Scientific Partnership - British Gas - Tunisian Society for Electricity and Gas - Imex Olive Oil -Confiserie TRIKI Le Moulin The next MSM conference in 2005 will be held in Morocco.

  13. Preface: phys. stat. sol. (c) 1/9

    NASA Astrophysics Data System (ADS)

    Leitch, Andrew; Botha, Reinhardt

    2004-08-01

    The Conference on Photo-responsive Materials took place at the Kariega Game Reserve in the Eastern Cape, South Africa from 25-29 February 2004. More than 60 delegates from 12 different countries participated in the four-day event.The purpose of the conference was to bring together scientists working on various aspects of photo-responsive materials, so as to stimulate this important field of solid state physics in Southern Africa. As may be seen from the list of papers appearing in these proceedings, there was much interest in copper indium diselenide as a thin film material for photovoltaic applications. Also worth mentioning were the valuable contributions on ZnO, GaN and other materials that are currently attracting attention worldwide.The conference program allowed sufficient time for interaction and exchanging of views. Being in a game reserve in the heart of the beautiful Eastern Cape, delegates were also taken on game drives and had the opportunity of taking a river cruise up the Kariega River to view the majestic fish eagle.The members of the academic program committee were: Vivian Alberts (Rand Afrikaans University), Danie Auret (University of Pretoria), Darrell Comins (University of the Witwatersrand), and Reinhardt Botha and Andrew Leitch (University of Port E All papers appearing in these proceedings underwent a strict reviewing process separate from the conference. We express our appreciation to the referees for their diligence in this important task. The conference was organized by the Department of Physics at the University of Port Elizabeth, under the auspices of the Condensed Matter Physics and Materials Science (CMPMS) subgroup of the South African Institute of Physics. It was sponsored by EMF Limited (UK), Sensors Unlimited Inc. (USA), and Carl Zeiss (Pty) Ltd. Special thanks must go to Dr Eunete van Wyk for her professional assistance in the preparation of these proceedings.

  14. Preface: phys. stat. sol. (c) 1/6

    NASA Astrophysics Data System (ADS)

    Kavokin, Alexey

    2004-04-01

    This volume contains some of the papers presented at the Third International Conference on Physics of Light-Matter Coupling in Nanostructures (PLMCN3) which took place in Acireale, Sicily, from 1 to 4 October 2003. This meeting was fourth in the series started by PLMCN (St. Nectaire, 2000) and continued by PLMCN1 (Rome, 2001) and PLMCN2 (Rithymnon, 2002). All four conferences had the same format (about 70 participants), similar subject scope (interface between fundamental physics of light-matter coupling phenomena and applied research on new semiconductor materials and low-dimensional structures), and the proceedings of all of them have been published in physica status solidi.During these four years, a huge progress has been achieved in the understanding of exciton-polariton effects in microcavities. From the discovery of stimulated scattering of polaritons in 1999 to the first experimental reports of polariton Bose condensation and lasing, attention to this rapidly developing research area has been increased drastically. It is clear now that realization of a new generation of opto-electronic devices, referred to as polariton devices, is a realistic task for the coming decade. To achieve this target, much work has to be done both in fundamental research on dynamics of exciton-polaritons in microcavities and experimental realization of high-quality microcavities presumably based on wide-band gap semiconductors like GaN, ZnO, ZnSe, suitable for the observation of strong exciton-light coupling at room temperature. Forty nine research teams from twelve European countries have created a Polariton Consortium aimed at integration of the European research effort towards fabrication of polariton devices. PLMCN3 was not only an international conference devoted, in particular, to the research on polariton devices, but also the first scientific meeting of this community.The PLMCN meetings since the very first one have been sponsored by the US Army European Research Office (ERO). This time, with the initiative of Jim Harvey from ERO, a special session has been organized on the devices of 21st century, where a number of intriguing ideas have been proposed on new light sources, polariton lasers, and quantum memory elements based on microcavities. A special prize for the most crazy but realizable idea has been won by Misha Portnoi (Exeter) for the concept of a white diode based on a microcavity.Each PLMCN meeting brings participants from new countries. This time, the traditionally strong participation from Japan, Russia, the European Union and the USA has been enforced by a representative delegation from Israel and two speakers from Mexico. We are looking forward for new-comers from other countries not yet involved in the PLMCN community, to join us for the next meeting to be held in St. Petersburg on 29 June-3 July 2004. Sergey Ivanov from the A. F. Ioffe Institute chairs the local Organizing Committee of this future conference. We are going to keep a unique informal and creative atmosphere being characteristic of the PLMCN meetings. We invite all those who wish to know more about light-matter coupling in solids or to present any new interesting results in this area and at the same time to enjoy the beautiful city of St. Petersburg, to contact Sergey Ivanov (ivan@beam.ioffe.rssi.ru) or myself (kavokin@lasmea.univ-bpclermont.fr). We are looking forward to welcoming you in St. Petersburg!

  15. Editorial: phys. stat. sol. (c) 3/1

    NASA Astrophysics Data System (ADS)

    Stutzmann, Martin

    2006-01-01

    Dear Colleagues and Friends,on behalf of the Publishers, the Editorial Office, and the Editors of physica status solidi we wish you all the best for the coming year 2006! It is our sincere hope that your personal and professional experience with our journal has been a positive one and that you will continue to choose physica status solidi for the publication of your scientific findings in solid state physics also in the future.In doing so, you will be in increasingly good company! As a matter of fact, 2005 has been a year of exceptional growth in the number of manuscripts submitted to physica status solidi . Thus, the number of Original Papers which have reached our Editorial Office in Berlin has increased by as much as 30% compared to the long term average over the last ten years. For the Rapid Research Letter section, the corresponding increase has been even more impressive: more than +100% just in the last two years. We view this development as a confirmation of our longstanding efforts to ensure a timely publication service of high scientific quality. One relevant indicator for the high scientific standards expected from articles which are submitted for publication in physica status solidi is the average acceptance rate, which currently is less than 40%. This rate has continuously decreased from a value of about 60% ten years ago and bears witness to our efforts to strive for quality rather than quantity.Also, physica status solidi has been able to continue its long tradition as a truly international journal, despite of the strong competition in an established field such as solid state physics. In 2005, submitted papers have originated almost equally from the Americas, Europe, and Asia, with a clearly growing contribution from China, India, and Japan. We are actively working together with our international Editorial Boards and the Regional Editors to maintain a reasonable balance among papers from different parts of the world. The increasing international visibility of physica status solidi is impressively documented by the ever rising numbers of article downloads via the internet: on the average, each of the 2000 articles published annually in physica status solidi is presently accessed about 100 times via the www. Finally, let me mention some other recent developments, which are not so directly visible from the outside. Thus, a new all electronic publishing system has become operative in our Berlin Editorial Office in 2005, which allows a more efficient and timely handling of manuscripts from submission to publication (www.manuscriptXpress.com) and is particularly valuable for the editing of conference proceedings (conferences.wiley-vch.de). In addition, the functionality of the journal within the Wiley InterScience website has been enhanced by new features such as Citation Tracking. Together with the ongoing digitization of all physica status solidi issues since the 1960s, which is expected to be complete in 2006, this makes the physica status solidi homepage at Wiley InterScience a very valuable tool for literature search in solid state physics, past and present. Try it out at www.interscience.wiley.com! All of us from physica status solidi would like to convey to you our very best wishes for good health and success in the coming year 2006!

  16. Editorial: phys. stat. sol. (a) 203/1

    NASA Astrophysics Data System (ADS)

    Stutzmann, Martin

    2006-01-01

    Dear Colleagues and Friends,on behalf of the Publishers, the Editorial Office, and the Editors of physica status solidi we wish you all the best for the coming year 2006! It is our sincere hope that your personal and professional experience with our journal has been a positive one and that you will continue to choose physica status solidi for the publication of your scientific findings in solid state physics also in the future.In doing so, you will be in increasingly good company! As a matter of fact, 2005 has been a year of exceptional growth in the number of manuscripts submitted to physica status solidi. Thus, the number of Original Papers which have reached our Editorial Office in Berlin has increased by as much as 30% compared to the long term average over the last ten years. For the Rapid Research Letter section, the corresponding increase has been even more impressive: more than +100% just in the last two years. We view this development as a confirmation of our longstanding efforts to ensure a timely publication service of high scientific quality. One relevant indicator for the high scientific standards expected from articles which are submitted for publication in physica status solidi is the average acceptance rate, which currently is less than 40%. This rate has continuously decreased from a value of about 60% ten years ago and bears witness to our efforts to strive for quality rather than quantity.Also, physica status solidi has been able to continue its long tradition as a truly international journal, despite of the strong competition in an established field such as solid state physics. In 2005, submitted papers have originated almost equally from the Americas, Europe, and Asia, with a clearly growing contribution from China, India, and Japan. We are actively working together with our international Editorial Boards and the Regional Editors to maintain a reasonable balance among papers from different parts of the world. The increasing international visibility of physica status solidi is impressively documented by the ever rising numbers of article downloads via the internet: on the average, each of the 2000 articles published annually in physica status solidi is presently accessed about 100 times via the www.Finally, let me mention some other recent developments, which are not so directly visible from the outside. Thus, a new all electronic publishing system has become operative in our Berlin Editorial Office in 2005, which allows a more efficient and timely handling of manuscripts from submission to publication (www.manuscriptXpress.com) and is particularly valuable for the editing of conference proceedings (conferences.wiley-vch.de). In addition, the functionality of the journal within the Wiley InterScience website has been enhanced by new features such as Citation Tracking. Together with the ongoing digitization of all physica status solidi issues since the 1960s, which is expected to be complete in 2006, this makes the physica status solidi homepage at Wiley InterScience a very valuable tool for literature search in solid state physics, past and present. Try it out at www.interscience.wiley.com!All of us from physica status solidi would like to convey to you our very best wishes for good health and success in the coming year 2006!

  17. Editorial: phys. stat. sol. (b) 243/1

    NASA Astrophysics Data System (ADS)

    Stutzmann, Martin

    2006-01-01

    Dear Colleagues and Friends,on behalf of the Publishers, the Editorial Office, and the Editors of physica status solidi we wish you all the best for the coming year 2006! It is our sincere hope that your personal and professional experience with our journal has been a positive one and that you will continue to choose physica status solidi for the publication of your scientific findings in solid state physics also in the future.In doing so, you will be in increasingly good company! As a matter of fact, 2005 has been a year of exceptional growth in the number of manuscripts submitted to physica status solidi . Thus, the number of Original Papers which have reached our Editorial Office in Berlin has increased by as much as 30% compared to the long term average over the last ten years. For the Rapid Research Letter section, the corresponding increase has been even more impressive: more than +100% just in the last two years. We view this development as a confirmation of our longstanding efforts to ensure a timely publication service of high scientific quality. One relevant indicator for the high scientific standards expected from articles which are submitted for publication in physica status solidi is the average acceptance rate, which currently is less than 40%. This rate has continuously decreased from a value of about 60% ten years ago and bears witness to our efforts to strive for quality rather than quantity.Also, physica status solidi has been able to continue its long tradition as a truly international journal, despite of the strong competition in an established field such as solid state physics. In 2005, submitted papers have originated almost equally from the Americas, Europe, and Asia, with a clearly growing contribution from China, India, and Japan. We are actively working together with our international Editorial Boards and the Regional Editors to maintain a reasonable balance among papers from different parts of the world. The increasing international visibility of physica status solidi is impressively documented by the ever rising numbers of article downloads via the internet: on the average, each of the 2000 articles published annually in physica status solidi is presently accessed about 100 times via the www.Finally, let me mention some other recent developments, which are not so directly visible from the outside. Thus, a new all electronic publishing system has become operative in our Berlin Editorial Office in 2005, which allows a more efficient and timely handling of manuscripts from submission to publication (www.manuscriptXpress.com) and is particularly valuable for the editing of conference proceedings (conferences.wiley-vch.de). In addition, the functionality of the journal within the Wiley InterScience website has been enhanced by new features such as Citation Tracking. Together with the ongoing digitization of all physica status solidi issues since the 1960s, which is expected to be complete in 2006, this makes the physica status solidi homepage at Wiley InterScience a very valuable tool for literature search in solid state physics, past and present. Try it out at www.interscience.wiley.com!All of us from physica status solidi would like to convey to you our very best wishes for good health and success in the coming year 2006!

  18. Preface: phys. stat. sol. (a) 201/11

    NASA Astrophysics Data System (ADS)

    Bergonzo, Philippe; Haenen, Ken; Nebel, Christoph; Nesládek, Milo; Vanek, Milan

    2004-09-01

    The present issue of physica status solidi (a) contains a collection of 24 papers presented at the 9th International Workshop on Surface and Bulk Defects in CVD Diamond Films held in Diepen- beek-Hasselt, Belgium, 18-20 February 2004. The concept of this workshop originated in 1996 with the idea of bringing together scientists who are active and innovative in the field of electronic and optical properties of thin film diamond. Since then, this meeting have grown up to a regular conference devoted to new issues in CVD diamond research and related to diamond as a material for electronics and nanobioelectronics. This year the programme was spread over two and a half days, including 8 invited lectures from a total of 39 talks, and a poster session featuring 15 posters. In addition we were able to connect this meeting with a workshop on Defects and Impurities in Crystalline Boron Nitride Compounds, scientifically organized from the University of Antwerp and leading finally to a joint meeting lasting four days. The papers from the BN workshop are joining this proceeding issue on pages 2559-2598.At SBDD IX, topics ranged from homo- and heteroepitaxial growth, doping, hydrogen induced surface conductivity, defects and their characterization, to devices including bio-sensing applications. As usual, very intense and lively discussions took place among participants, from young students to established scientists, after talks, during breaks and in the evenings while enjoying the hospitality of the Limburgs Universitair Centrum and especially the city of Hasselt. The number of participants reached a record breaking 96 this year, with participants coming from fifteen different countries (Australia, Austria, Belgium, Czech Republic, France, Germany, Israel, Italy, Japan, Mexico, Romania, Russia, Sweden, UK, USA). This yearly increasing number indicates that this workshop is continuing to be very attractive to a large scientific community, as it summarizes the up-to-date research on diamond as a wide band gap semiconductor.The workshop would have not been possible without the support of many people and institutions. For financial aid we are especially indebted to the Scientific Research Community Surface Modification of Materials of the F. W. O.-Vlaanderen (Belgium) and its continuous support since starting this workshop 9 years ago. We also thank the Limburgs Universitair Centrum for offering the lecture hall and infrastructure facilities. Finally we highly appreciate the active approach of the editorial staff of physica status solidi in this conference and would like to thank most notably Stefan Hildebrandt and Katharina Fröhlich, for their excellent and patient work, making this already the sixth successfully published proceedings of SBDD in pss (a).To finish, we would all like to invite you for the 10th anniversary of the SBDD series in February 2005 in Diepenbeek-Hasselt and we look forward to seeing you at:Surface and Bulk Defects in CVD Diamond Films, X23-25 February 2005Limburgs Universitair Centrum, Diepenbeek - Hasselt, Belgiumhttp://www.imo.luc.ac.be/SBDD2005

  19. Preface: phys. stat. sol. (a) 203/12

    NASA Astrophysics Data System (ADS)

    Jackman, Richard B.; Nesládek, Milo; Haenen, Ken

    2006-09-01

    The 30 papers gathered in this issue of physica status solidi (a) give a thorough overview over different topics that were presented during the 11th edition of the International Workshop on Surface and Bulk Defects in CVD Diamond Films (SBDD), which took place from 22 to 24 February 2006, at the Hasselt University in Diepenbeek-Hasselt, Belgium. Since its start more than 10 years ago, the SBDD Workshop has grown into a well-established, yearly early bird meeting place, addressing new emerging science related to the progress in the CVD diamond field. The 10 invited lectures, 29 contributed oral presentations and 26 posters were presented in several sessions during an intense two and a half day long meeting.The number of participants reached 115 this year with participants coming from fifteen countries: Austria, Belgium, Czech Republic, France, Germany, Israel, Italy, Japan, Mexico, Poland, Russia, Singapore, Slovak Republic, Sweden, UK, and USA. The mixture of young and established scientists, including a great proportion of students, made this meeting a hot spot of lively discussions on a wide range of scientific subjects, not only during the meeting itself, but also at several occasions throughout many social events offered by the hospitality of the city of Hasselt.It stands for itself that the workshop would not have been possible without the support of many people and institutions. For financial aid we are especially indebted to the Scientific Research Community Surface Modification of Materials of the F.W.O.-Vlaanderen (Belgium), whose incessant support plays an important role in keeping this meeting going. We also thank the Hasselt University for offering the lecture hall and infrastructure facilities and Seki Technotron Corp. for sponsoring the poster reception and their presence with a table top exhibit. Finally we highly appreciate the active approach of the editorial staff of physica status solidi in this conference and would like to thank most notably Stefan Hildebrandt, Ron Schulz-Rheinländer, Christoph Lellig, and Julia Hübner, for their excellent and patient work, bringing the number of successfully published proceedings of SBDD in pss (a) up to 8 already!To finish, we would all like to invite you to the 12th edition of the SBDD series, newly renamed as Hasselt Diamond Workshop, to be held at its established location of Diepenbeek-Hasselt. We look forward meeting you again at SBDD XII in 2007:Hasselt Diamond Workshop - SBDD XII28 February-2 March 2007Hasselt University, Diepenbeek-Hasselt, Belgiumhttp://www.imo.uhasselt.be/SBDD2007London, Paris, Hasselt, August 2006

  20. Preface: phys. stat. sol. (c) 1/10

    NASA Astrophysics Data System (ADS)

    Suh, Eun-Kyung; Yoon, Euijoon; Lee, Hyung Jae

    2004-09-01

    The Fifth International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004) was held in Gyeongju, Korea from 15-19 March 2004. Gyeongju, the ancient capital of the thousand-year Silla kingdom (57 B.C. to 935 A.D.) provided additional pleasure to the participants as an exceptional open-air museum with antique treasures scattered all around the city.During the last decade we have witnessed remarkable developments in wide-gap semiconductors and light emitting devices in the spectral range from the visible to deep UV. The purpose of the Symposium was to provide a forum for intensive discussion on the issues and main progress especially in optoelectronic devices, material growth and characterization, and quantum structures of wide bandgap semiconductors. A total of 243 papers including 220 contributed and 23 invited ones were presented and discussed by 487 participants from 17 countries world-wide. Among them, 154 manuscripts were submitted and reviewed by the usual evaluation process of physica status solidi. Some were rejected or withdrawn, and finally 139 papers are published in the special issues of physica status solidi (a), (b), and (c). We gratefully acknowledge the referees for their careful review. The papers are grouped into 7 categories. The subheadings and the number of papers in each are as follows: Optoelectronic devices, 43; Growth and characterization, 45; Nano and quantum structures, 21; Contacts, 8; Zinc oxide, 9; Indium nitride and indium rich InGaN, 6; Others, 7. The special session of the Symposium, The LED Highlight, designed partially to meet the challenging targets of the technology, i.e., energy savings and clean environment preservation, drew much attention and is edited as a special coloured section in this issue.The next symposium is scheduled for Montpellier, France, in 2006. We wish the organizers of that symposium the best of luck and hope to see all of the ISBLLED-2004 participants again at ISBLLED-2006.ISBLLED-2004 was sponsored by The Research Society for the Wide-gap Semiconductors, Korean Physical Society, Office of Naval Research, Korea Science and Engineering Foundation, Korea Research Foundation, Korea Association for Photonics Industry Development, Asian Office of Aerospace Research and Development, and Korea Photonics Technology Institute. We would like to thank Ms. E. S. Hwang for her devotion to the preparation and the Proceedings of the symposium including the manuscript handling for publication.

  1. Preface: phys. stat. sol. (a) 201/8

    NASA Astrophysics Data System (ADS)

    Shin, Sung-Chul

    2004-06-01

    The KMS/SOMMA Meeting 2003 was held 3-6 December 2003 at Spapia Hotel, Daejeon, Korea. It was the 5th SOMMA (International Symposium on Magnetic Materials and Applications) organized by ReCAMM (Research Center for Advanced Magnetic Materials) of Chungnam National University. Since 2002, the Korean Magnetics Society (KMS) winter conference has been jointly held with SOMMA. This was the second time to have a KMS/SOMMA joint meeting. The main objective of the meeting was to provide an international forum to discuss up-to-date results on magnetism and magnetic materials. The conference brought together 360 participants from 12 countries. Sessions of the meeting were: Theory and Fundamentals, Magnetic Random Access Memory, Spintronics, Information Storage, Nanostructured Materials, Sensors, and Interdisciplinary. In these seven sessions, 325 papers were presented including 66 oral and 259 poster presentations. Since the symposium was held in Korea, this enabled a large number of Asian scientists to attend: 239 from Korea, 41 from Japan, 7 from Taiwan, and 5 from China.The conference program had 25 invited and plenary speakers. They were Y. Ando (Tohoku U.), M. Inoue (Toyohashi U. Tech), H. Kubota (Tohoku U.), K. Mohri (Nagoya U.), M. Sahashi, M. Takahashi, K. Takanashi, M. Tsunoda (Tohoku U.), and H. Yoda (Toshiba) from Japan; A. J. Freeman (Northwestern U.), A. T. Hanbicki (NRL), F. B. Humphrey (Boston U.), and S. Sun (IBM) from the USA; J. D. Boeck (IMEC, Belgium), B. Dieny (CEA, France), N. Garcia (CSIS, Spain), G. Reiss (Bielefeld U., Germany), T. Stobiecki (U. M. & M. Krakow, Poland), and M. Wolfram (Singulus Tech, Germany) from Europe; C. G. Kim, D. J. Kim (CNU), T. W. Kim (SAIT), S. H. Lim (KIST), Sung-Chul Shin (KAIST), and Yoon Hee Chung (POSTEC) from Korea.For the first time, the SOMMA Proceedings appear in physica status solidi. The Editors hope that the Proceedings could provide chances for deeper and wider understanding of the presentations as well as for enhanced relationship between all participants. We deeply appreciate the help of the editorial staff of physica status solidi for their efficient and kind help during the paper preparations and publications.Finally, we would like to take this opportunity to thank all members of the Advisory Committee, Organizing Committee, referees, and KMS staff for their effort before, during, and after the meeting.

  2. Preface: phys. stat. sol. (b) 241/7

    NASA Astrophysics Data System (ADS)

    Shin, Sung-Chul

    2004-06-01

    The KMS/SOMMA Meeting 2003 was held 3-6 December 2003 at Spapia Hotel, Daejeon, Korea. It was the 5th SOMMA (International Symposium on Magnetic Materials and Applications) organized by ReCAMM (Research Center for Advanced Magnetic Materials) of Chungnam National University. Since 2002, the Korean Magnetics Society (KMS) winter conference has been jointly held with SOMMA. This was the second time to have a KMS/SOMMA joint meeting.The main objective of the meeting was to provide an international forum to discuss up-to-date results on magnetism and magnetic materials. The conference brought together 360 participants from 12 countries. Sessions of the meeting were: Theory and Fundamentals, Magnetic Random Access Memory, Spintronics, Information Storage, Nanostructured Materials, Sensors, and Interdisciplinary. In these seven sessions, 325 papers were presented including 66 oral and 259 poster presentations. Since the symposium was held in Korea, this enabled a large number of Asian scientists to attend: 239 from Korea, 41 from Japan, 7 from Taiwan, and 5 from China.The conference program had 25 invited and plenary speakers. They were Y. Ando (Tohoku U.), M. Inoue (Toyohashi U. Tech), H. Kubota (Tohoku U.), K. Mohri (Nagoya U.), M. Sahashi, M. Takahashi, K. Takanashi, M. Tsunoda (Tohoku U.), and H. Yoda (Toshiba) from Japan; A. J. Freeman (Northwestern U.), A. T. Hanbicki (NRL), F. B. Humphrey (Boston U.), and S. Sun (IBM) from the USA; J. D. Boeck (IMEC, Belgium), B. Dieny (CEA, France), N. Garcia (CSIS, Spain), G. Reiss (Bielefeld U., Germany), T. Stobiecki (U. M. & M. Krakow, Poland), and M. Wolfram (Singulus Tech, Germany) from Europe; C. G. Kim, D. J. Kim (CNU), T. W. Kim (SAIT), S. H. Lim (KIST), Sung-Chul Shin (KAIST), and Yoon Hee Chung (POSTEC) from Korea.For the first time, the SOMMA Proceedings appear in physica status solidi. The Editors hope that the Proceedings could provide chances for deeper and wider understanding of the presentations as well as for enhanced relationship between all participants. We deeply appreciate the help of the editorial staff of physica status solidi for their efficient and kind help during the paper preparations and publications.Finally, we would like to take this opportunity to thank all members of the Advisory Committee, Organizing Committee, referees, and KMS staff for their effort before, during, and after the meeting.

  3. Preface: phys. stat. sol. (b) 242/13

    NASA Astrophysics Data System (ADS)

    Esser, Norbert; Zahn, Dietrich R. T.

    2005-11-01

    Wolfgang Richter celebrated his 65th birthday on 2 January 2005. On such an occasion, usually marking retirement, achievements and breakthroughs in research are reviewed. But Wolfgang Richter is not retiring: he has accepted an offer of a professorship at the University Rome II Tor Vergata. As he explained to us with his famous smile, he plans to concentrate his future efforts even more on his true love in science - the optical diagnostics of interfaces.Wolfgang Richter has been working in the field of optical spectroscopy of solids since his PhD studies at the University of Cologne. Having finished his PhD in 1969 in the field of infrared spectroscopy he decided to reduce the probed volume by increasing the energy of probing photons: Raman spectroscopy! During his postdoctoral and Habilitation periods (1970-1979) at Pennsylvania State University, Max-Planck-Institut für Festkörperforschung, and RWTH Aachen, he pursued his interest in resonance Raman spectroscopy on semiconductors.In 1979 he received his first appointment as full professor at the University of Ulm. He returned to RWTH Aachen in 1981 and discovered his true destiny: semiconductor interfaces. At that time in the Department of Semiconductor Technology, metal-organic vapour phase epitaxy (MOVPE) was under development as a new technique for growing semiconductor layers. The underlying processes in MOVPE were known to be complex and very difficult to analyse with available experimental techniques, due to the unfriendly, reactive gas phase environment. Optical diagnostics turned out to be the key to a better understanding of MOVPE processes. Wolfgang Richter moved from RWTH Aachen to TU Berlin at the end of 1988 and began building a strong research group concentrating on interface analysis from two complementary sides: on the one hand, tracking MOVPE growth processes online by in situ optics and, on the other hand, advancing the fundamental understanding of optical spectra of interfaces by relating the optical response to atomic structures. Combining both aspects has finally led to considerable progress in surface and interface optics, as well as in vapour phase epitaxy and, moreover, the in situ optical tools developed are nowadays available as standard options in commercial MOVPE machines.The advances largely concerned the development of reflectance anisotropy spectroscopy and spectroscopic ellipsometry as in situ optical tools. However, considerable progress in Raman spectroscopy was also made: analysis of surfaces, ultrathin layers down to a single monolayer or even sub-monolayer coverages, and sub-wavelength spatial resolution were demonstrated in recent years. Current challenges concern, in particular, organic materials, molecule-solid interfaces and bio-interfaces, which will help in the development of many new applications and devices. Interfaces will play a crucial role in many of these developments and optical spectroscopy offers promising capabilities for analysing such interfaces. Wolfgang Richter and his group at University of Rome II Tor Vergata are sure to be active in this emerging field for a long time to come.Based on a symposium on Optical Spectroscopy of Interfaces at the Spring Meeting of the German Physical Society in Berlin 2005, we have asked former and present colleagues of Wolfgang Richter to contribute to this special issue of physica status solidi (b) on Advanced Optical Diagnostics of Surfaces, Nanostructures and Ultrathin Films. We think that the collection of 26 papers gives an excellent overview on recent achievements and future developments in the field of linear optics. In addition to a number of Original Papers on experimental work and some Review Articles, the issue includes examples of the current approaches of computational theory to solid state optics and interface optics. We hope that this issue will stimulate the expansion of the growing field of optical analysis of interfaces, nanostructures and ultrathin layers into new areas of basic and applied science. After the success in characterising inorganic materials, it is

  4. Dedication: phys. stat. sol. (a) 202/15

    NASA Astrophysics Data System (ADS)

    Albrecht, Martin

    2005-12-01

    The papers in this issue are dedicated to Professor Horst Paul Strunk on the occasion of his 65th birthday and his retirement from active teaching. This volume honours a scientist who has made a lasting impact on the field in electron microscopic characterisation of growth and relaxation phenomena in epitaxial growth of semiconductors. Born in The Hague, The Netherlands, on 13 June 1940, he studied physics in Stuttgart where he received his degree in Physics in 1968. He joined the group of Prof. Seeger at the Max-Planck-Institut für Metallforschung and defended his Ph.D. on defects in NaCl at Stuttgart University in 1973. He spent one year at Cornell University as a visiting Professor before joining Technische Universität Hamburg-Harburg in 1983. There he created the Zentralbereich Elektronenmikroskopie and was a professor for materials analytics from 1983 till 1989. In 1989 he changed to the University of Erlangen-Nürnberg, where he established the Verbundlabor für hochauflösende Elektronenmikroskopie and directed the Lehrstuhl Mikrocharakterisierung at the Institut für Werkstoffwissenschaften of the same university. He spent two research periods at the Universities of Rennes in France and Campinas in Brazil. Together with his colleague Prof. Jürgen Werner he created the series of conferences on polycrystalline semiconductors POLYSE which he has been supervising together with Jürgen Werner since 1990.The research activities of Horst P. Strunk are focused on microstructure of materials and their relation to macroscopic physical properties. Main topics are dislocations, their formation and interaction mechanisms, strain relaxation as well as fundamental mechanisms of epitaxial growth. The spectrum of materials covers a wide range starting from metals over ionic crystals, e.g. NaCl to elemental and compound semiconductors. From the beginning, the main tool of study has been the transmission electron microscope. However, Horst P. Strunk recognised that a thorough understanding of materials problems would require the combined use of structural characterisation, advanced spectroscopy and modelling. Therefore he complemented electron microscopic approaches by optical methods e.g. Raman spectroscopy and cathodoluminescence. Modelling of strain states by finite elements and of defect structures by ab-initio calculations became an important topic especially in the last years. It is characteristic for the scientific approach of Horst Strunk that methodological developments were not an end in itself but linked to problems in solid state physics and materials sciences. Among the scientific works of Strunk, a few examples should be highlighted which mark important stages in his scientific career. Pioneering work has been done on the influence of dislocations in homoepitaxial growth of Si and GaAs in collaboration with Elisabeth Bauser in Stuttgart. Strunk correlated growth spirals on the surface to dislocations that caused these step sources. Studying the dislocation structure of heteroepitaxial Ge/GaAs layers, Strunk discovered that a new dislocation multiplication source works which, later known as Hagen-Strunk source, had a strong impact on understanding of relaxation processes by dislocations in heteroepitaxial semiconductor systems. Work on electrical and structural properties of grain boundaries in silicon was performed together with Jürgen Werner. This was the starting point of a long lasting research on photovoltaic materials that accompanies Strunk till today. Fundamental studies on heteroepitaxial growth were performed in the system SiGe grown from solution. In this context, finite elements were established for the first time in the study of nanostructured materials. In the last years correlated studies on structural and optical properties on III-nitride heterostructures were done by cathodoluminescence in the transmission electron microscope. The impact of Horst P. Strunk's work is evident from the fact that his lab became part of collaborative international projects based on the unique facilities at the Verbundlabor für Hochauflösende Elektronenmikroskopie and the profound knowledge in the field of crystal growth and solid state physics present in his group. The articles in this issue contain original research results contributed by his friends, collaborators and former students. They are a testimony of the lasting impact of Horst P. Strunk's work and they express the authors' gratefulness for benefiting from his work. This volume gives us a unique opportunity to say thank you to Horst P. Strunk and to wish him a new period in his life that should continue to be scientifically as fruitful as up to now but less affected by the burden of administrative work than during the last years.

  5. Preface: phys. stat. sol. (b) 243/5

    NASA Astrophysics Data System (ADS)

    Artacho, Emilio; Beck, Thomas L.; Hernández, Eduardo

    Between 20 and 24 June 2005 the Centre Européen de Calcul Atomique et Moléculaire - or CECAM, as it is more widely known - hosted a workshop entitled State-of-the-art, developments and perspectives of real-space electronic structure methods in condensed-matter and chemical physics, organized with the support of CECAM itself and the ?k network. The workshop was attended by some forty participants coming from fifteen countries, and about thirty presentations were given. The workshop provided a lively forum for the discussion of recent methodological developments in electronic structure calculations, ranging from linear-scaling methods, mesh techniques, time-dependent density functional methods, and a long etcetera, which had been our ultimate objective when undertaking its organization.The first-principles simulation of solids, liquids and complex matter in general has jumped in the last few years from the relatively confined niches in condensed matter and materials physics and in quantum chemistry, to cover most of the sciences, including nano, bio, geo, environmental sciences and engineering. This effect has been propitiated by the ability of simulation techniques to deal with an ever larger degree of complexity. Although this is partially to be attributed to the steady increase in computer power, the main factor behind this change has been the coming of age of the main theoretical framework for most of the simulations performed today, together with an extremely active development of the basic algorithms for its computer implementation. It is this latter aspect that is the topic of this special issue of physica status solidi.There is a relentless effort in the scientific community seeking to achieve not only higher accuracy, but also more efficient, cost-effective and if possible simpler computational methods in electronic structure calculations [1]. From the early 1990s onwards there has been a keen interest in the computational condensed matter and chemical physics communities in methods that had the potential to overcome the unfavourable scaling of the computational cost with the system size, implicit in the momentum-space formalism familiar to solid-state physicists and the quantum chemistry approaches more common in chemical physics and physical chemistry. This interest was sparkled by the famous paper in which Weitao Yang [2] introduced the Divide and Conquer method. Soon afterwards several practical schemes aiming to achieve linear-scaling calculations, by exploiting what Walter Kohn called most aptly the near-sightedness of quantum mechanics [3], were proposed and explored (for a review on linear-scaling methods, see [4]). This search for novel, more efficient and better scaling algorithms proved to be fruitful in more than one way. Not only was it the start of several packages which are well-known today (such as Siesta, Conquest, etc.), but it also leads to new ways of representing electronic states and orbitals, such as grids [5, 6], wavelets [7], finite elements, etc. Also, the drive to exploit near-sightedness attracted computational solid state physicists to the type of atomic-like basis functions traditionally used in the quantum chemistry community. At the same time computational chemists learnt about plane waves and density functional theory, and thus a fruitful dialogue was started between two communities that hitherto had not had much contact.Another interesting development that has begun to take place over the last decade or so is the convergence of several branches of science, notably physics, chemistry and biology, at the nanoscale. Experimentalists in all these different fields are now performing highly sophisticated measurements on systems of nanometer size, the kind of systems that us theoreticians can address with our computational methods, and this convergence of experiment and theory at this scale has also been very fruitful, particularly in the fields of electronic transport and STM image simulation. It is now quite common to find papers at the cutting edge of nanoscience and nanotechnology co-authored by experimentalists and theorists, and it can only be expected that this fruitful interplay between theory and experiment will increase in the future.It was considerations such as these that moved us to propose to CECAM and ?k the celebration of a workshop devoted to the discussion of recent developments in electronic structure techniques, a proposal that was enthusiastically received, not just by CECAM and ?k, but also by our invited speakers and participants. Interest in novel electronic structure methods is now as high as ever, and we are therefore very happy that physica status solidi has given us the opportunity to devote a special issue to the topics covered in the workshop. This special issue of physica status solidi gathers invited contributions from several attendants to the workshop, contributions that are representative of the range of topics and issues discussed then, including progress in linear scaling methods, electronic transport, simulation of STM images, time-dependent DFT methods, etc. It rests for us to thank all the contributors to this special issue for their efforts, CECAM and ?k for funding the workshop, physica status solidi for agreeing to devote this special issue to the workshop, and last but not least Emmanuelle and Emilie, the CECAM secretaries, for their invaluable practical help in putting this workshop together

  6. Preface: phys. stat. sol. (a) 203/4

    NASA Astrophysics Data System (ADS)

    Kittler, Martin; Yang, Deren

    2006-03-01

    This issue of physica status solidi (a) contains the majority of papers presented at the 2nd Sino-German Symposium The Silicon Age which was held at the Lindner Hotel Cottbus, Germany, 19-24 September 2005. This meeting followed the 1st Symposium Progress in Silicon Materials held in June 2002 in Hangzhou, P.R. China. 8 Chinese and 14 German scientists from universities, research institutes and industry were invited to present their views about different aspects of silicon.There was a continuous progress in silicon materials development during the last 40-50 years, driven by the need of the IC industry for better and larger monocrystalline silicon wafers. Moreover, low-cost crystalline silicon now dominates the world's production of solar cells in the photovoltaics industry. Furthermore, there are intensive research activities worldwide for on-chip integration of Si-based photonics in CMOS technology. In addition, new areas being connected with silicon are starting to appear, namely Si-based biochips and nanoelectronics. Silicon, one can reasonably argue, is already the most investigated of all materials. However, there is still a need for continuation of research and development regarding numerous aspects of Si and also SiGe, including related technologies, advanced diagnostics or the role of crystal defects, which are the working fields of many laboratories all over the world. This was also shown by the presentations at the symposium and can be found in the contributions contained in this issue.The organizers would like to thank the participants for their high level contributions and discussions during the symposium. This intensive and open communication allowed the participants to create synergies between the different fields of silicon research and also to build up relationships for cooperation between Chinese and German research groups.Finally, we would like to thank the Sino-German Science Center for the financial support of the symposium.

  7. 75 FR 23729 - Orders Finding that the (1) Phys,1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-04

    ....3(c) promulgated thereunder. \\10\\ 74 FR 53724 (October 20, 2009). DATES: Effective Date: April 28... determined closing, settlement or other daily price of another contract. \\13\\ 74 FR 12178 (Mar. 23, 2009...., 2d Sess. 978, 986 (Conference Committee Report). See also 73 FR 75888, 75894 (Dec. 12, 2008)....

  8. Schools in Most States Skimp on Phys Ed, Study Finds

    MedlinePlus

    ... news is that school districts, under a recent law, will be able to get federal funding to improve their programs, the report said. SOURCE: Voices for Healthy Kids, news release, April 8, 2016 HealthDay Copyright (c) 2016 HealthDay . All rights reserved. News stories ...

  9. 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. PMID:27423564

  10. 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.

  11. 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}.

  12. 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.

  13. Orthorhombic aluminium oxyfluoride, AlOF.

    PubMed

    Vasiliev, Alexander D; Melnikova, Svetlana V; Isaenko, Lyudmila I

    2009-04-01

    Crystals of the title compound were extracted from the bulk of grown SrAlF(5) crystals as unexpected inclusions that were identified as the long sought after aluminium oxyfluoride. The structure of AlOF is built up from tetrahedral and octahedral polyhedra. Each tetrahedron is bisected by a mirror plane, with the Al atom and two vertex anions in the plane. All tetrahedral vertices are positions of competing oxide and fluoride ions and are shared with octahedra. These shared vertices belong to two octahedral edges which join the octahedra to form infinite zigzag chains. The chains are strung along twofold screw axes that run parallel to the unit-cell b axis. The remaining two octahedral vertices are occupied only by fluoride ions. A small deficiency in the occupation of the octahedral Al position was suggested by the refinement. However, the stoichiometry of the compound is AlOF within experimental uncertainty. The Al-F(O) distances are separated into three groups with average values of 1.652 (3) (tetrahedra), 1.800 (2) (octahedra) and 1.894 (2) A (octahedra). This structure differs widely from the reported tetragonal phase Al(1-x)O(1-3x)F(1+3x) (x = 0.0886) [Kutoglu (1992). Z. Kristallogr. 199, 197-201], which consists solely of octahedral structural units. PMID:19346595

  14. Electrical conductivity of Al-bearing bridgmanite

    NASA Astrophysics Data System (ADS)

    Yoshino, T.; Kamada, S.; Ohtani, E.; Hirao, N.

    2015-12-01

    Electrical conductivity measurements of bridgmanite with various Al contents and constant Mg# 90 at room temperature up to 2000 K and 26-28 GPa were performed in Kawai-type multianvil apparatus using impedance spectroscopic analyses. The incorporation of Al into bridgmanite significantly raises the electrical conductivity but it is small conductivity variation with respect to the amount of Al. Synchrotron Mössbauer spectroscopy of recovered samples showed a significant amount of ferric iron in aluminous bridgmanite. The mobility of charge carriers in bridgmanite was calculated from the conductivity and Fe3+/ΣFe. A relation between the logarithm of electrical conductivity and reciprocal temperature is consistent with Fe2+-Fe3+ electron hopping (small polaron) as the dominant conduction mechanism at low temperatures (< 1400 K) and ionic conduction at high temperatures (> 1600 K). Taking various conduction mechanisms into account, we develop an electrical conductivity model for aluminous bridgmanite as a function of Al and Fe content. This conductivity model suggests that the electrical conductivity of aluminous bridgmanite has a maximum at around 0.13 Al per formula unit, and further increase of Al in bridgmanite reduces the conductivity. The conductivity increase observed in the uppermost lower mantle by electromagnetic studies can be explained by increases of Fe and Na content in combination with substitution of Al into bridgmanite with increasing pressure due to the gradual decomposition of majorite garnet.

  15. Comparative study on interface and bulk charges in AlGaN/GaN metal-insulator-semiconductor heterostructures with Al2O3, AlN, and Al2O3/AlN laminated dielectrics

    NASA Astrophysics Data System (ADS)

    Zhu, Jie-Jie; Ma, Xiao-Hua; Chen, Wei-Wei; Hou, Bin; Xie, Yong; Hao, Yue

    2016-05-01

    In this paper, the interface and bulk charges in AlGaN/GaN metal-insulator-semiconductor (MIS) heterostructures with AlN, Al2O3, and Al2O3/AlN laminated dielectrics were studied. In situ plasma pretreatment resulted negligible interface trap states and voltage hysteresis. The fixed charge density at Al2O3/AlN (or Al2O3/barrier) interface was estimated to be 1.66 × 1013 cm-2 by using flat-band voltage shift, and the oxide bulk charge concentration was 2.86 × 1017 cm-3. The interface charge density at other interfaces were at the order of 1011 cm-2. Simulation results using the above charge density/concentration indicated that Al2O3/AlN interface fixed charges dominated the dielectric-related voltage shift in AlGaN/GaN MIS heterostructures, which caused a large voltage shift of -3 V with 10 nm Al2O3 thickness, while the flat-band voltage variety resulting from other types of charges was within 0.1 V.

  16. 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. PMID:26613179

  17. Hybrid Al + Al3Ni metallic foams synthesized in situ via laser engineered net shaping

    NASA Astrophysics Data System (ADS)

    Zheng, Baolong; Li, Ying; Smugeresky, John E.; Zhou, Yizhang; Baker, Dean; Lavernia, Enrique J.

    2011-09-01

    A hybrid, Al + Al3Ni metallic foam was synthesized in situ via laser engineered net shaping (LENS®) of Ni-coated 6061 Al powder in the absence of a foaming agent. During LENS® processing, the Ni coating reacted with the Al matrix, resulting in the simultaneous formation of a fine dispersion of Al3Ni, and a high volume fraction of porosity. As a reinforcement phase, the intermetallic compound formed particles with a size range of 1-5 µm and a volume fraction of 63%, with accompanying 35-300 µm pores with a 60% volume fraction. The microstructure of the as-deposited Al + Al3Ni composite foams was characterized using SEM, EDS, XRD and TEM/HRTEM techniques. The evolution of the microstructure was analyzed on the basis of the thermal field present during deposition, paying particular attention to the thermodynamics of the Al3Ni intermetallic compound formation as well as discussing the mechanisms that may be responsible for the observed porosity. The mechanical behavior of the as-deposited material was characterized using compression and microhardness testing, indicating that the yield strength and hardness are 190 MPa and 320 HV, respectively, which represents an increase of over three times higher than that of annealed Al6061, or similar to heat-treated Al6061 fully dense matrix, and much higher than those of traditional Al alloy foams, and with a low density of 1.64 g/m3.

  18. Optical characterization of Al- and N-polar AlN waveguides for integrated optics

    NASA Astrophysics Data System (ADS)

    Rigler, Martin; Buh, Jože; Hoffmann, Marc P.; Kirste, Ronny; Bobea, Milena; Mita, Seiji; Gerhold, Michael D.; Collazo, Ramon; Sitar, Zlatko; Zgonik, Marko

    2015-04-01

    Dispersion of the extraordinary and ordinary refractive indices of Al- and N-polar AlN waveguides is measured by multiple angle-of-incidence and spectroscopic ellipsometry techniques. The polarity-controlled AlN layers are grown by metal-organic chemical vapor deposition on (0001)-sapphire substrates. Taking into consideration the different surface morphologies of the Al- and N-polar AlN waveguides, we propose two optical models to describe the measured ellipsometry data. The results indicate that there is no difference between the refractive indices of the AlN grown in opposite directions, which confirms the potential of the AlN lateral polar structures for use in nonlinear optical applications based on quasi phase matching.

  19. A Rechargeable Al/S Battery with an Ionic-Liquid Electrolyte.

    PubMed

    Gao, Tao; Li, Xiaogang; Wang, Xiwen; Hu, Junkai; Han, Fudong; Fan, Xiulin; Suo, Liumin; Pearse, Alex J; Lee, Sang Bok; Rubloff, Gary W; Gaskell, Karen J; Noked, Malachi; Wang, Chunsheng

    2016-08-16

    Aluminum metal is a promising anode material for next generation rechargeable batteries owing to its abundance, potentially dendrite-free deposition, and high capacity. The rechargeable aluminum/sulfur (Al/S) battery is of great interest owing to its high energy density (1340 Wh kg(-1) ) and low cost. However, Al/S chemistry suffers poor reversibility owing to the difficulty of oxidizing AlSx . Herein, we demonstrate the first reversible Al/S battery in ionic-liquid electrolyte with an activated carbon cloth/sulfur composite cathode. Electrochemical, spectroscopic, and microscopic results suggest that sulfur undergoes a solid-state conversion reaction in the electrolyte. Kinetics analysis identifies that the slow solid-state sulfur conversion reaction causes large voltage hysteresis and limits the energy efficiency of the system. PMID:27417442

  20. 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.

  1. High performance AlGaN/GaN HEMTs with AlN/SiNx passivation

    NASA Astrophysics Data System (ADS)

    Xin, Tan; Yuanjie, Lü; Guodong, Gu; Li, Wang; Shaobo, Dun; Xubo, Song; Hongyu, Guo; Jiayun, Yin; Shujun, Cai; Zhihong, Feng

    2015-07-01

    AlGaN/GaN high electron-mobility transistors (HEMTs) with 5 nm AlN passivation by plasma enhanced atomic layer deposition (PEALD) were fabricated, covered by 50 nm SiNx which was grown by plasma enhanced chemical vapor deposition (PECVD). With PEALD AlN passivation, current collapse was suppressed more effectively and the devices show better subthreshold characteristics. Moreover, the insertion of AlN increased the RF transconductance, which lead to a higher cut-off frequency. Temperature dependence of DC characteristics demonstrated that the degradations of drain current and maximum transconductance at elevated temperatures for the AlN/SiNx passivated devices were much smaller compared with the devices with SiNx passivation, indicating that PEALD AlN passivation can improve the high temperature operation of the AlGaN/GaN HEMTs. Project supported by the National Natural Science Foundation of China (No. 60890192).

  2. 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.

  3. Suspected variables among Al Sufi stars.

    NASA Astrophysics Data System (ADS)

    Hoffleit, D.

    In the tenth century Al Sufi compiled a catalogue of some 1100 stars. J.E. Gore, around 1900, wrote extensively on the magnitudes of these stars. On intercomparing them with a few other catalogues, Gore surmised that some 38 stars appeared to show secular variations. Here all the Al Sufi magnitudes have been compared with numerous additional sources, but smooth secular variations are not substantiated although some stars seem to have undergone comparatively sudden changes after about 1600. About 70 Al Sufi stars are now named or suscpected variable stars, but nearly all with amplitudes under 0.3 V.

  4. Optical emission spectroscopy and time-of-flight investigations of plasmas generated from AlN targets in cases of pulsed laser deposition with sub-ps and ns ultraviolet laser pulses

    NASA Astrophysics Data System (ADS)

    Ristoscu, Carmen; Mihailescu, Ion N.; Velegrakis, Michalis; Massaouti, Maria; Klini, Argyro; Fotakis, Costas

    2003-02-01

    We performed a comparative study of the plasma generated from AlN targets under sub-ps vs ns UV (λ=248 nm) excimer laser pulses. Optical emission and time-of-flight spectra recorded in cases of samples irradiated with ns laser pulses showed the presence of Al lines, which became prevalent after the first laser pulse was incident on the target. These observations are congruent with the metallization of AlN targets inside each crater under multipulse ns laser action at laser fluences above the ablation threshold, observed by visual inspection and optical microscopy. Metallization was not observed when working with sub-ps laser pulses. Moreover, our studies confirmed the predominant presence of AlN positive molecular ions in the plasma generated in front of AlN targets submitted to sub-ps multipulse laser irradiation. The optical emission data are in good agreement with time-of-flight mass analysis. We emphasize that all investigations support the experimental evidence reported by György et al. [E. György et al., J. Appl. Phys. 90, 456 (2001)], according to which thin films obtained by pulsed laser deposition with ns laser pulses contain a significant amount of metallic Al, while only AlN is detected in films obtained with sub-ps laser pulses. Measurements of the velocity and kinetic energy distributions of AlN+ indicate that in the case of ns-laser ablation the ions are emitted with thermal energy, while in the case of sub-ps-laser ablation a bimodal distribution exists and has thermal (1 eV) and hyperthermal (10 eV) energy components. This points to different plasma formation mechanisms for the two cases.

  5. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    NASA Astrophysics Data System (ADS)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-05-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1} 2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1} 2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  6. Characterization of AlInN/AlN/GaN Heterostructures with Different AlN Buffer Thickness

    NASA Astrophysics Data System (ADS)

    Çörekçi, S.; Dugan, S.; Öztürk, M. K.; Çetin, S. Ş.; Çakmak, M.; Özçelik, S.; Özbay, E.

    2016-07-01

    Two AlInN/AlN/GaN heterostructures with 280-nm- and 400-nm-thick AlN buffer grown on sapphire substrates by metal-organic chemical vapor deposition (MOCVD) have been investigated by x-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) and Hall-effect measurements. The symmetric (0002) plane with respect to the asymmetric (10bar{1}2) plane in the 280-nm-thick AlN buffer has a higher crystal quality, as opposed to the 400-nm-thick buffer. The thinner buffer improves the crystallinity of both (0002) and (10bar{1}2) planes in the GaN layers, it also provides a sizeable reduction in dislocation density of GaN. Furthermore, the lower buffer thickness leads to a good quality surface with an rms roughness of 0.30 nm and a dark spot density of 4.0 × 108 cm-2. The optical and transport properties of the AlInN/AlN/GaN structure with the relatively thin buffer are compatible with the enhancement in its structural quality, as verified by XRD and AFM results.

  7. 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.

  8. Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2012-03-01

    Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ˜0 eV results from electroforming. Electroforming of Al-Al2O3-Ag diodes with amorphous anodic Al2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of Al2O3 and negative charge in Al2O3 are much larger when Al2O3 is formed in bor-H2O solution than when Al is anodized in bor-gly solution. Electroforming of Al-Al2O3-Ag diodes results in an Ohmic contact at the Al-Al2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for Al-Al2O3-Ag diodes. α-forming occurs for 2.5 V ≲ VS ≲ 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. β-forming occurs for VS ≳ 7 V. I-V curves, EL, and EM develop gradually and are smaller than for α-forming. Electroforming occurs more readily for diodes with Al2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after α-forming or β-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic Al2O3, form defect conduction bands. Electroforming that results in an Ohmic

  9. Stability, elastic properties and fracture toughness of Al0.75X0.75B14 (X=Sc, Ti, V, Cr, Y, Zr, Nb, Mo) investigated using ab initio calculations.

    PubMed

    Emmerlich, Jens; Thieme, Niklas; to Baben, Moritz; Music, Denis; Schneider, Jochen M

    2013-08-21

    The effect of the transition metal valence electron concentration on the energy of formation, effective charge of B icosahedra, elastic properties, surface energy and fracture toughness was calculated using density functional theory for icosahedral transition metal borides of AlXB14 (X=Sc, Ti, V, Cr, Y, Zr, Nb, Mo). Consistent with previous work on AlYB14 (Kölpin et al 2009 J. Phys.: Condens. Matter 21 355006) it is shown that phase stability is generally dependent on the effective charge of the icosahedral transition metal borides. Also, ionization potential and electronegativity are identified as parameters affecting the effective charge of B icosahedra suitable for use in predicting the phase stability. Al0.75Y0.75B14, Al0.75Sc0.75B14 and Al0.75Zr0.75B14 have been identified as promising phases for application as protective coatings as they exhibit high phase stability and stiffness combined with a comparatively high fracture toughness. PMID:23877961

  10. Molecular modeling of Al 3+ and benzene interactions with Suwannee fulvic acid

    NASA Astrophysics Data System (ADS)

    Trout, Chad C.; Kubicki, James D.

    2007-08-01

    The effects that Al 3+ and benzene interactions exhibit on a model fulvic acid were investigated. Energy minimizations of the structures mimicking the interactions of Al 3+-Suwannee fulvic acid (SFA), benzene-SFA and Al 3+-benzene-SFA were run with a solvation sphere of 60 H 2O molecules with the semi-empirical methods PM3 and PM5. The semi-empirical method PM3 was run with Gaussian 98 and CAChe Workstation Pro 6.1.1 to compare the results of the energy minimization algorithms in the two programs. PM5 calculations were run with CAChe Workstation Pro 6.1.1. Molecular dynamics (MD) simulations were run in Cerius 2 (Accelrys Inc., San Diego, CA) using the Universal Force Field (UFF) 1.02 [Rappé A. K., Casewit C., Colwell K., Goddard W., and Skiff W. (1992) UFF, a full periodic-table force-field for molecular mechanics and molecular dynamics simulations. J. Am. Chem. Soc.114(25), 10024-10035] and COMPASS force field [Sun H. (1998) COMPASS: an ab initio force-field optimized for condensed-phase applications—overview with details on alkane and benzene compounds. J. Phys. Chem. B102, 7338-7364]. Single point calculations were run on the minimized structures at the B3LYP/6-31G(d) level to obtain more accurate estimates of the energy on the minimized structures derived from the PM3, PM5, and UFF methods and to normalize energies to the same reference state. This methodology was used as the standard of comparison for all the models to assess whether or not a given configuration was reasonably stable. The PM3/G03 energy minimizations predicted the lowest B3LYP/6-31G(d) potential energies of the methodologies examined in this study. Thus, this method is considered the most reliable of those tested. The PM3/G03 method predicted that there would be aromatic-aromatic interactions between benzene and SFA. The presence of Al 3+ was predicted not to interfere with aromatic-aromatic interactions between benzene and SFA, but benzene may influence the location of metal complexation

  11. Stem Cells Deemed Safe for ALS Patients

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_159627.html Stem Cells Deemed Safe for ALS Patients But further research ... June 29, 2016 (HealthDay News) -- Scientists report that stem cell therapy appears to be safe for people with ...

  12. Pesticides Linked to Raised Risk of ALS

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_158737.html Pesticides Linked to Raised Risk of ALS One toxin ... MONDAY, May 9, 2016 (HealthDay News) -- Exposure to pesticides and other chemicals may increase the risk for ...

  13. Stem Cells Deemed Safe for ALS Patients

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_159627.html Stem Cells Deemed Safe for ALS Patients But further ... June 29, 2016 (HealthDay News) -- Scientists report that stem cell therapy appears to be safe for people ...

  14. 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

  15. Glial cells in ALS: the missing link?

    PubMed

    Raibon, Elsa; Todd, Lisa Marie; Möller, Thomas

    2008-08-01

    Amyotrophic lateral sclerosis (ALS) was initially known as Charcot's sclerosis, named after the French neurobiologist and physician Jean-Martin Charcot who first described this type of muscular atrophy in the early nineteenth century. In the United States, ALS became widely known as Lou Gehrig's disease after the famous baseball player who succumbed to the disease in the late 1930s. Currently, ALS is the most common motor neuron disease, with a worldwide incidence of 8 cases per 100,000 population per year. Familial forms constitute approximately 5% to 10% of all cases. Onset increases with age, with a peak in the seventh decade and a slight preponderance (relative risk, 1.3-1.5) among men compared with women. Rapid progression of motor neuron loss leads to death an average of 3 to 5 years after symptom onset. The cause of ALS remains unknown and there is still no curative therapy. PMID:18625409

  16. Thermal Conductivity of Al-Salt Composites

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Mei; Wang, Lijun; Seetharaman, Seshadri

    2015-11-01

    With a view to examine the possibility of estimating the content of entrapped metallic aluminium in the salt cake from aluminium remelting, the thermal diffusivity of reference composites of KCl-NaCl-Al was measured as a function of aluminium metal content at room temperature. The thermal conductivity of the reference composites was found to increase with the metallic Al content. The lumped parameter model approach was carried out to discuss the influence of different geometry arrangements of each phase, viz. air, salts and metallic aluminium on the thermal conductivity. Application of the present results to industrial samples indicates that factors such as the interfacial condition of metallic Al particles have to be considered in order to estimate the amount of entrapped Al in the salt cake.

  17. ALS: Recent Developments from Genetics Studies.

    PubMed

    Therrien, Martine; Dion, Patrick A; Rouleau, Guy A

    2016-06-01

    Amyotrophic lateral sclerosis (ALS) is a fatal disorder that is characterized by a progressive degeneration of the upper and lower motor neurons. Most cases appear to be sporadic, but 5-10 % of cases have a family history of the disease. High-throughput DNA sequencing and related genomic capture tools are methodological advances which have rapidly contributed to an acceleration in the discovery of genetic risk factors for both familial and sporadic ALS. It is interesting to note that as the number of ALS genes grows, many of the proteins they encode are in shared intracellular processes. This review will summarize some of the recent advances and gene discovery made in ALS. PMID:27113253

  18. Pesticides Linked to Raised Risk of ALS

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_158737.html Pesticides Linked to Raised Risk of ALS One toxin ... MONDAY, May 9, 2016 (HealthDay News) -- Exposure to pesticides and other chemicals may increase the risk for ...

  19. 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.

  20. Itinerant antiferromagnetism of TiAl alloys

    NASA Astrophysics Data System (ADS)

    Petrişor, T.; Pop, I.; Giurgiu, A.; Farbaş, N.

    1986-06-01

    Magnetic susceptibility measurements of TiAl alloys are reported. Aluminium, by alloying, acts on the Néel temperature of pure titanium giving rise to a complicated phase diagram. A theoretical model, based on the itinerant antiferromagnetism model of chromium is proposed in order to explain the magnetic phase diagram of TiAl alloys. The experimental and theoretical magnetic phase diagram are in good agreement.

  1. Magnetism of Al-Mn quasicrystals

    SciTech Connect

    Liu, F.; Khanna, S.N.; Magaud, L.; Jena, P. ); de Coulon, V.; Reuse, F. ); Jaswal, S.S.; He, X. ); Cyrot-Lackman, F. )

    1993-07-01

    The effect of symmetry and concentration of Mn on the magnetism of Al-Mn quasicrystals has been investigated through self-consistent density-functional calculations using molecular clusters and supercell band-structure schemes. A single Mn atom surrounded by 54 Al atoms in an icosahedral or a cuboctahedral structure is found to be nonmagnetic. However, as the Mn concentration is increased, moments develop on Mn sites whose magnitude and coupling depend on their location.

  2. Next-generation sequencing of 28 ALS-related genes in a Japanese ALS cohort.

    PubMed

    Nakamura, Ryoichi; Sone, Jun; Atsuta, Naoki; Tohnai, Genki; Watanabe, Hazuki; Yokoi, Daichi; Nakatochi, Masahiro; Watanabe, Hirohisa; Ito, Mizuki; Senda, Jo; Katsuno, Masahisa; Tanaka, Fumiaki; Li, Yuanzhe; Izumi, Yuishin; Morita, Mitsuya; Taniguchi, Akira; Kano, Osamu; Oda, Masaya; Kuwabara, Satoshi; Abe, Koji; Aiba, Ikuko; Okamoto, Koichi; Mizoguchi, Kouichi; Hasegawa, Kazuko; Aoki, Masashi; Hattori, Nobutaka; Tsuji, Shoji; Nakashima, Kenji; Kaji, Ryuji; Sobue, Gen

    2016-03-01

    We investigated the frequency and contribution of variants of the 28 known amyotrophic lateral sclerosis (ALS)-related genes in Japanese ALS patients. We designed a multiplex, polymerase chain reaction-based primer panel to amplify the coding regions of the 28 ALS-related genes and sequenced DNA samples from 257 Japanese ALS patients using an Ion Torrent PGM sequencer. We also performed exome sequencing and identified variants of the 28 genes in an additional 251 ALS patients using an Illumina HiSeq 2000 platform. We identified the known ALS pathogenic variants and predicted the functional properties of novel nonsynonymous variants in silico. These variants were confirmed by Sanger sequencing. Known pathogenic variants were identified in 19 (48.7%) of the 39 familial ALS patients and 14 (3.0%) of the 469 sporadic ALS patients. Thirty-two sporadic ALS patients (6.8%) harbored 1 or 2 novel nonsynonymous variants of ALS-related genes that might be deleterious. This study reports the first extensive genetic screening of Japanese ALS patients. These findings are useful for developing genetic screening and counseling strategies for such patients. PMID:26742954

  3. Metastability in the MgAl2O4-Al2O3 System

    DOE PAGESBeta

    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

  4. Excitotoxicity in ALS: Overstimulation, or overreaction?

    PubMed

    King, Anna E; Woodhouse, Adele; Kirkcaldie, Matthew T K; Vickers, James C

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease that results in motor dysfunction and death, generally from respiratory failure. 90% of ALS cases are sporadic with no known cause. Familial cases have been linked with mutations in several disparate classes of genes, including those involved in DNA/RNA metabolism, protein misfolding, oxidative stress and the cytoskeleton, leading to the proposition that ALS could be a multi-factorial disease. However, alterations in excitability have been reported in all types of ALS cases, and may be a common disease mechanism predisposing neurons to degeneration. Excitotoxicity has long been suspected as a mediator in the disease process, and may arise from changes in synaptic inputs, or alterations in the excitability of the neurons being stimulated. Although the glutamatergic system is widely recognised as a therapeutic avenue with the potential to extend lifespan and delay disease onset, the causes of altered excitability in ALS are currently unclear and warrant further investigation. This article reviews current evidence of alterations to excitatory and inhibitory signalling in the cortex and spinal cord, and in the intrinsic excitability of motor neurons, in ALS. PMID:26584004

  5. Clinical trials for neuroprotection in ALS.

    PubMed

    Siciliano, G; Carlesi, C; Pasquali, L; Piazza, S; Pietracupa, S; Fornai, F; Ruggieri, S; Murri, L

    2010-07-01

    Owing to uncertainty on the pathogenic mechanisms underlying motor neuron degeneration in amyotrophic lateral sclerosis (ALS) riluzole remains the only available therapy, with only marginal effects on disease survival. Here we review some of the recent advances in the search for disease-modifying drugs for ALS based on their putative neuroprotective effetcs. A number of more or less established agents have recently been investigated also in ALS for their potential role in neuroprotection and relying on antiglutamatergic, antioxidant or antiapoptotic strategies. Among them Talampanel, beta-lactam antibiotics, Coenzyme Q10, and minocycline have been investigated. Progress has also been made in exploiting growth factors for the treatment of ALS, partly due to advances in developing effective delivery systems to the central nervous system. A number of new therapies have also been identified, including a novel class of compounds, such as heat-shock protein co-inducers, which upregulate cell stress responses, and agents promoting autophagy and mitochondriogenesis, such as lithium and rapamycin. More recently, alterations of mRNA processing were described as a pathogenic mechanism in genetically defined forms of ALS, as those related to TDP-43 and FUS-TLS gene mutations. This knowledge is expected to improve our understanding of the pathogenetic mechanism in ALS and developing more effective therapies. PMID:20406180

  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. How common are ALS plateaus and reversals?

    PubMed Central

    Vaughan, Timothy; Wicks, Paul; Heywood, Jamie; Sinani, Ervin; Selsov, Roger; Macklin, Eric A.; Schoenfeld, David; Cudkowicz, Merit; Sherman, Alex

    2016-01-01

    Objective: To determine the frequency of amyotrophic lateral sclerosis (ALS) plateaus and reversals in the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) database. Methods: We analyzed Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS) and ALSFRS–revised (ALSFRS-R) data from PRO-ACT participants. The frequencies of participants experiencing plateaus (periods where scores did not change) were calculated over 6-, 12-, and 18-month epochs. The percentage of participants ever experiencing reversals (periods where scores improved) of different lengths were also calculated and plotted. Results: Over 6 months, 25% of 3,132 participants did not decline. Over 12 months, 16% of 2,105 participants did not decline. Over 18 months, 7% of 1,218 participants did not decline. Small ALS reversals were also common, especially over shorter follow-up intervals; 14% of 1,343 participants had a 180-day interval where their ALSFRS-R slope was greater than zero. Fewer than 1% of participants ever experienced improvements of 4 or more ALSFRS-R points lasting at least 12 months. Conclusion: ALS plateaus and small reversals are common, especially over brief intervals. In light of these data, stable disease, especially for a short period of time, should not be interpreted as an ALS treatment effect. Large sustained ALS reversals, on the other hand, are rare, potentially important, and warrant further study. PMID:26658909

  8. Ionization of Atoms by Slow Heavy Particles, Including Dark Matter

    NASA Astrophysics Data System (ADS)

    Roberts, B. M.; Flambaum, V. V.; Gribakin, G. F.

    2016-01-01

    Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9 σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times.

  9. Ionization of Atoms by Slow Heavy Particles, Including Dark Matter.

    PubMed

    Roberts, B M; Flambaum, V V; Gribakin, G F

    2016-01-15

    Atoms and molecules can become ionized during the scattering of a slow, heavy particle off a bound electron. Such an interaction involving leptophilic weakly interacting massive particles (WIMPs) is a promising possible explanation for the anomalous 9σ annual modulation in the DAMA dark matter direct detection experiment [R. Bernabei et al., Eur. Phys. J. C 73, 2648 (2013)]. We demonstrate the applicability of the Born approximation for such an interaction by showing its equivalence to the semiclassical adiabatic treatment of atomic ionization by slow-moving WIMPs. Conventional wisdom has it that the ionization probability for such a process should be exponentially small. We show, however, that due to nonanalytic, cusplike behavior of Coulomb functions close to the nucleus this suppression is removed, leading to an effective atomic structure enhancement. We also show that electron relativistic effects actually give the dominant contribution to such a process, enhancing the differential cross section by up to 1000 times. PMID:26824537

  10. Short-time dynamics of isotropic and anisotropic Bak-Sneppen model: extensive simulation results

    NASA Astrophysics Data System (ADS)

    Tirnakli, Ugur; Lyra, Marcelo L.

    2004-12-01

    In this work, the short-time dynamics of the isotropic and anisotropic versions of the Bak-Sneppen (BS) model has been investigated using the standard damage spreading technique. Since the system sizes attained in our simulations are larger than the ones employed in previous studies, our results for the dynamic scaling exponents are expected to be more accurate than the results of the existing literature. The obtained scaling exponents of both versions of the BS model are found to be greater than the ones given in previous works. These findings are in agreement with the recent claim of Cafiero et al. (Eur. Phys. J. B7 (1999) 505). Moreover, it is found that the short-time dynamics of the anisotropic model is only slightly affected by finite-size effects and the reported estimate of α≃0.53 can be considered as a good estimate of the true exponent in the thermodynamic limit.

  11. Scheme for implementing perfect quantum teleportation with four-qubit entangled states in cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Tang, Jing-Wu; Zhao, Guan-Xiang; He, Xiong-Hui

    2011-05-01

    Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω4>1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics.

  12. On the critical packet injection rate of a preferential next-nearest neighbor routing traffic model on Barabási-Albert networks

    NASA Astrophysics Data System (ADS)

    Chau, H. F.; Chan, H. Y.; Chow, F. K.

    2009-12-01

    Recently, Yin et al. [Eur. Phys. J. B 49, 205 (2006)] introduced an efficient small-world network traffic model using preferential next-nearest neighbor routing strategy with the so-called path iteration avoidance (PIA) rule to study the jamming transition of internet. Here we study their model without PIA rule by a mean-field analysis which carefully divides the message packets into two types. Then, we argue that our mean-field analysis is also applicable in the presence of PIA rule in the limit of a large number of nodes in the network. Our analysis gives an explicit expression of the critical packet injection rate Rc as a function of a bias parameter of the routing strategy α in their model with or without PIA rule. In particular, we predict a sudden change in Rc at a certain value of α. These predictions agree quite well with our extensive computer simulations.

  13. Stabilization of traffic flow in optimal velocity model via delayed-feedback control

    NASA Astrophysics Data System (ADS)

    Jin, Yanfei; Hu, Haiyan

    2013-04-01

    Traffic jams may occur due to various reasons, such as traffic accidents, lane reductions and on-ramps. In order to suppress the traffic congestion in an optimal velocity traffic model without any driver's delay taken into account, a delayed-feedback control of both displacement and velocity differences is proposed in this study. By using the delay-independent stability criteria and the H∞-norm, the delayed-feedback control can be determined to stabilize the unstable traffic flow and suppress the traffic jam. The numerical case studies are given to demonstrate and verify the new control method. Furthermore, a comparison is made between the new control method and the method proposed by Konishi et al. [K. Konishi, M. Hirai, H. Kokame, Decentralized delayed-feedback control of an optimal velocity traffic model, Eur. Phys. J. B 15 (2000) 715-722]. The results show that the new control method makes the traffic flow more stable and improves the control performance.

  14. λ-DNA thermal migration in a microchannel

    NASA Astrophysics Data System (ADS)

    Kreft, Jennifer; Chen, Yeng-Long

    2007-03-01

    The Ludwig-Soret effect, the migration of a species due to a temperature gradient, has been extensively studied without a complete picture of its cause. Many particle and polymer solutions have been used to study the phenomena; here we investigate the dynamics of DNA confined to a microchannel and subjected to a thermal gradient using a combination of Brownian dyanmics and the lattice Boltzmann method. We observe that the DNA molecules will migrate to colder regions of the channel, an observation also made in the experiments of Duhr, et al (Eur. Phys. J. E, 15, (2004)). In fact, the thermal diffusion coefficient found for a range of temperature gradients and DNA molecular weights agrees nearly quantitatively with the experimental value. Furthermore, we use the simulation to understand how the interaction of the DNA with the solvent leads to thermal migration via the thermal fluctuations-fluid momentum flux coupling.

  15. Motif-based success scores in coauthorship networks are highly sensitive to author name disambiguation

    NASA Astrophysics Data System (ADS)

    Klosik, David F.; Bornholdt, Stefan; Hütt, Marc-Thorsten

    2014-09-01

    Following the work of Krumov et al. [Eur. Phys. J. B 84, 535 (2011), 10.1140/epjb/e2011-10746-5] we revisit the question whether the usage of large citation datasets allows for the quantitative assessment of social (by means of coauthorship of publications) influence on the progression of science. Applying a more comprehensive and well-curated dataset containing the publications in the journals of the American Physical Society during the whole 20th century we find that the measure chosen in the original study, a score based on small induced subgraphs, has to be used with caution, since the obtained results are highly sensitive to the exact implementation of the author disambiguation task.

  16. A New Method to Retrieve the Orbital Parameters of the Galilean Satellites Using Small Telescopes: A Teaching Experiment

    NASA Astrophysics Data System (ADS)

    Sanchez-Lavega, Agustin; Ordoñez-Etxebarria, Iñaki; del Rio-Gaztelurrutia, Teresa

    2014-11-01

    We show in this communication how it is possible to deduce the radius of the orbits of Galilean satellites around Jupiter using a small number of well-planned observations. This allows the instructor to propose a complete student activity that involves planning an observation, the observation itself, processing and analyzing the images and deduction of relevant magnitudes [1]. This work was performed in the Aula EspaZio Gela under the Master in Space Science and Technology [2].References[1] I. Ordoñez-Etxebarria, T. del Río Gaztelurrutia and A. Sánchez Lavega, European Journal of Physics, Eur. J. Phys., 35, 045020 (14pp), (2014)[2] A. Sánchez-Lavega et al., European Journal of Engineering Education, doi:10.1080/03043797.2013.788611 (2013)AcknowledgementsThis work was supported by a grant from Diputaciõn Foral de Bizkaia — Bizkaiko Foru Aldundia to the Aula Espazio Gela.

  17. Effects of the generalised uncertainty principle on quantum tunnelling

    NASA Astrophysics Data System (ADS)

    Blado, Gardo; Prescott, Trevor; Jennings, James; Ceyanes, Joshuah; Sepulveda, Rafael

    2016-03-01

    In a previous paper (Blado et al 2014 Eur. J. Phys. 35 065011), we showed that quantum gravity effects can be discussed with only a background in non-relativistic quantum mechanics at the undergraduate level by looking at the effect of the generalised uncertainty principle (GUP) on the finite and infinite square wells. In this paper, we derive the GUP corrections to the tunnelling probability of simple quantum mechanical systems which are accessible to undergraduates (alpha decay, simple models of quantum cosmogenesis and gravitational tunnelling radiation) and which employ the WKB approximation, a topic discussed in undergraduate quantum mechanics classes. It is shown that the GUP correction increases the tunnelling probability in each of the examples discussed.

  18. Stretching short DNAs in electrolytes.

    PubMed

    Wang, Jizeng; Fan, Xiaojun; Gao, Huajian

    2006-03-01

    This paper is aimed at a combined theoretical and numerical study of the force-extension relation of a short DNA molecule stretched in an electrolyte. A theoretical formula based on a recent discrete wormlike chain (WLC) model of Kierfeld et al. (Eur Phys. J. E, Vol. 14, pp.17-34, 2004) and the classical OSF mean-field theory on electrostatic stiffening of a charged polymer is numerically verified by a set of Brownian dynamics simulations based on a generalized bead-rod (GBR) model incorporating long-ranged electrostatic interactions via the Debye-Hueckel potential (DH). The analysis indicates that the stretching of a short DNA can be well described as a WLC with a constant effective persistent length. This contrasts the behavior of long DNA chains that are known to exhibit variable persistent lengths depending on the ion concentration levels and force magnitudes. PMID:16711068

  19. Influence of carriers injection conditions on current-voltage characteristic of InGaAs/InAlAs-based three-terminal ballistic junctions

    NASA Astrophysics Data System (ADS)

    Farhi, G.; Hackens, B.; Faniel, S.; Gustin, C.; Bayot, V.; Wallart, X.; Bollaert, S.; Cappy, A.; Vasallo, B. G.; Mateos, J.; Gonzalez, T.

    2004-03-01

    We report on nonlinear electrical properties of three-terminal ballistic junctions (TBJs), etched on a two-dimensional electron gas confined in an InGaAs/InAlAs heterostructure. Measurements are performed in the six-probe configuration between 4.2K and room temperature. We measure the voltage Vc generated at the central stem when voltages Vl and Vr are applied on the left and right branches of the TBJs in push-pull fashion (Vl = -Vr =V_0). We observe that the sign and the amplitude of the nonlinear Vc vs V0 characteristic are strikingly influenced by voltage biases applied on side gates as well as by the carriers injection conditions at the left and right branches (injection angle, collimation). In particular, sign reversal is observed in some conditions. The experimental results are compared with predictions by Xu (H.Q. Xu, Appl. Phys. Lett. 78, 2064 (2001)).

  20. 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)].

  1. Scattering induced by Al segregation in AlGaN/GaN heterostructures

    SciTech Connect

    Liu, Xiwen; Lu, Yanwu; Ji, Dong

    2015-08-17

    The effect of Al segregation near dislocations on the mobility of two-dimensional electron gas in AlGaN/GaN heterostructure-based high-electron-mobility transistors was investigated. Exponentially varied composition fluctuation was effective in describing Al segregation near dislocations when calculating scattering behavior. Mobility, which was limited by Al segregation surrounding dislocation lines, was calculated to be in the order of 10{sup 3} cm{sup 2}/Vs to 10{sup 6} cm{sup 2}/Vs. Results indicated that the mobility in AlGaN/GaN heterojunction was enhanced upon the reduction of dislocation density at low temperature. This study contributes to generating higher electron mobility in AlGaN/GaN heterojunctions.

  2. Thermal Properties in the MgAl2O4-Al2O3 System

    SciTech Connect

    Wilkerson, Dr. Kelley R.; Smith, Jeffrey D; Hemrick, James Gordon

    2013-01-01

    Compositional effects on the thermal diffusivity in the MgAl2O4-Al2O3 system were studied. The lowest thermal diffusivity, 0.0258 +/-5% cm/s, was measured between 79.8 and 83.9 wt% Al2O3 quenched from various temperatures between 1500 and 1700C. All of the chemistries in this range extend past the solvus, but still form a singe super-saturated spinel solid solution, regardless of quenching tempeature. A super-saturated metastable solid solution region was observed at 1500, 1600, and 1700C extending to 83.9, 85.2, and 87.1 wt% Al2O3, respectively. Beyond 83.9% Al2O3 a significant increase in thermal diffusivity, 11.7%, was observed and its attributed to precipiation of Al2O3 through spinodal decomposition.

  3. 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. PMID:22163924

  4. TEM studies of oxidized NiAl and Ni3Al cross sections

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Ruhle, M.

    1989-01-01

    Cross sections of oxide scale/(Ni-Al) intermetallics were prepared by a new method and studied using primarily TEM. The cross sections were prepared by encasing an oxidized metal specimen sandwich in a low-melting-temperature zinc alloy. Observations of oxidized zirconium-doped beta-NiAl cross sections revealed crystallographic voids beneath an adherent Al2O3 scale. The oxide-metal interface was incoherent, but a high dislocation density in the metal near the interface suggested that a large tensile stress was induced by the attached oxide scale. A duplex Al2O3-NiAl2O4 scale formed on zirconium-doped and zirconium/boron-doped gamma-prime-Ni3Al alloys. Additional results are presented involving oxidation mechanisms and oxide-metal interface structures.

  5. 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.

  6. 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.

  7. Remarks on Peinado et al.'s Analysis of J3Gen.

    PubMed

    Garcia-Alfaro, Joaquin; Herrera-Joancomartí, Jordi; Melià-Seguí, Joan

    2015-01-01

    Peinado et al. analyzed the security of the J3Gen pseudorandom number generator proposed by Melià-Seguí et al., and claimed weaknesses regarding its security properties. They also presented a deterministic attack based on the decimation of the J3Gen output sequences. We show that the assumptions made by Peinado et al. are not correct and that the proposed deterministic attack against J3Gen does not hold in practice. PMID:25781510

  8. 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)

  9. 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.

  10. Excited states of 26Al studied via the reaction 27Al(d,t)

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishal; Bhattacharya, C.; Rana, T. K.; Manna, S.; Kundu, S.; Bhattacharya, S.; Banerjee, K.; Roy, P.; Pandey, R.; Mukherjee, G.; Ghosh, T. K.; Meena, J. K.; Roy, T.; Chaudhuri, A.; Sinha, M.; Saha, A. K.; Asgar, Md. A.; Dey, A.; Roy, Subinit; Moin Shaikh, Md.

    2016-05-01

    The reaction 27Al(d,t) at 25 MeV was utilized to study the excited states of 26Al. The angular distributions of the observed excited states of 26Al were analyzed with zero range distorted wave Born approximation as well as by incorporating finite range correction parameters to extract spectroscopic factors. The two sets of extracted spectroscopic factors were compared with each other to see the effect of using finite range correction in the transfer form factor.

  11. Temperature dependence diode parameters studies of Al/CuPc/n-Si/Al structure

    NASA Astrophysics Data System (ADS)

    Kumar, Ratnesh; Kaur, Ramneek; Sharma, Mamta; Kaur, Maninder; Tripathi, S. K.

    2015-08-01

    This paper presents the fabrication of Al/CuPc/n-Si/Al metal-organic-semiconductor diode. The copper phthalocyanine as organic layer is deposited on Si substrate by thermal evaporation technique. The temperature dependent current-voltage measurements are performed on Al/CuPc/n-Si structure. The important diode parameters i.e. the barrier height and ideality factor have been calculated. The temperature dependence of barrier height and ideality factor has been studied.

  12. 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.

  13. The new structure type Gd3Ni7Al14.

    PubMed

    Pukas, Svitlana; Gladyshevskii, Roman

    2015-11-01

    The crystal structure of Gd3Ni7Al14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (Al4Gd2 and Al6) are observed, the Al atoms are inside tetragonal (Ni2Al2Gd4, Ni2Al4Gd2, Al4Gd4, Ni4Al4 and Al8) and pentagonal (Ni4Al6 and Al10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4Al6) and hexagonal (Ni4Al8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7Al14 are similar to those of the intermetallides PrNi2Al3 and ZrNiAl. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2Al3 and ZrNiAl types. In the case of Gd3Ni7Al14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges. PMID:26524174

  14. Long range order and vacancy properties in Al-rich Fe{sub 3}Al and Fe{sub 3}Al(Cr) alloys

    SciTech Connect

    Kim, S.M.; Morris, D.G.

    1998-05-01

    Neutron powder diffraction measurements have been carried out in situ from room temperature to about 100 C in Fe28Al (28 at.% Al), Fe32.5Al (32.5 at.% Al) and Fe28Al15Cr (28 at.% Al, 5 at.% Cr) alloys. X-ray diffraction and TEM studies provided supporting information. The data were analyzed to obtain information about the temperature dependence of the DO{sub 3} and B2 long range order parameters, the location of the Cr atoms and their effect on the ordering energies, and on the vacancy formation and migration properties in Fe28Al and Fe32.5Al alloys. The location of the ternary alloying addition in DO{sub 3} and B2 ordered Al-rich Fe{sub 3}Al is shown to be consistent with considerations of interatomic bond energies.

  15. Strain Rates and Grain Growth in Al 5754 and Al 6061 Friction Stir Spot Welds

    NASA Astrophysics Data System (ADS)

    Gerlich, A.; Yamamoto, M.; North, T. H.

    2007-06-01

    The stir zone temperature and microstructures are compared in friction stir spot welds produced in Al 5754 and Al 6061 alloys. Electron backscattered diffraction was used to determine the relationship between tool rotation speed during welding and final stir zone grain size. Comparison of the grain sizes in rapidly quenched welds with those in air-cooled joints confirmed that grain growth occurred only in Al 6061 spot welds. There was no evidence of abnormal grain growth in the stir zones of Al 6061 welds; the final grain size could be represented using an Arrhenius equation. The strain rates during welding were determined by incorporating the stir zone temperature and average subgrain sizes in quenched spot welds in the Zener-Hollomon relation. When the tool rotation speed increased from 750 to 3000 RPM, the strain rate values ranged from 180 to 497 s-1 in Al 5754 spot welds and from 55 to 395 s-1 in Al 6061 spot welds. It is suggested that a no-slip boundary condition may be appropriate during numerical modeling of Al 5754 and 6061 friction stir spot welding. This is not the case during Al 7075, Al 2024, and Mg-alloy AZ91 spot welding because spontaneous melting facilitates slippage at the tool contact interface.

  16. 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.

  17. 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.

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

    PubMed

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

    2016-05-20

    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. PMID:27053603

  19. HYDROGEN ADSORPTION ON β-TiAl (001) AND Ni/TiAl (001) SURFACES

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A. Karim; Alelaimi, Mahmoud

    2014-04-01

    In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni/TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the β-TiAl system. This absorption reduces the cohesive energy of β-TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al. The adsorption of H atom on both terminations of H/Ni/TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d-Ni bands and TiAl substrate band.

  20. 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.

  1. AlN/IDT/AlN/Sapphire SAW Heterostructure for High-Temperature Applications.

    PubMed

    Legrani, Ouarda; Aubert, Thierry; Elmazria, Omar; Bartasyte, Ausrine; Nicolay, Pascal; Talbi, Abdelkrim; Boulet, Pascal; Ghanbaja, Jaafar; Mangin, Denis

    2016-06-01

    Recent studies have evidenced that Pt/AlN/Sapphire surface acoustic wave (SAW) devices are promising for high-temperature high-frequency applications. However, they cannot be used above 700°C in air atmosphere as the Pt interdigital transducers (IDTs) agglomerate and the AlN layer oxidizes in such conditions. In this paper, we explore the possibility to use an AlN protective overlayer to concurrently hinder these phenomena. To do so, AlN/IDT/AlN/Sapphire heterostructures undergo successive annealing steps from 800°C to 1000°C in air atmosphere. The impact of each step on the morphology, microstructure, and phase composition of AlN and Pt films is evaluated using optical microscopy, scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), and secondary ion mass spectroscopy (SIMS). Finally, acoustical performance at room temperature of both protected and unprotected SAW devices are compared, as well as the effects of annealing on these performance. These investigations show that the use of an overlayer is one possible solution to strongly hinder the Pt IDTs agglomeration up to 1000°C. Moreover, AlN/IDT/AlN/Sapphire SAW heterostructures show promising performances in terms of stability up to 800°C. At higher temperatures, the oxidation of AlN is more intense and makes it inappropriate to be used as a protective layer. PMID:27076407

  2. Microstructure and strengthening of creep-tested cryomilled NiAl-AlN

    SciTech Connect

    Garg, A.; Whittenberger, J.D.; Luton, M.J.

    1997-12-31

    The B2 intermetallic NiAl is considered to be a prime candidate material for use as very high temperature structural components in gas turbine engines. The mechanical grinding of prealloyed NiAl powder in liquid nitrogen (cryomilling) results in an intermetallic matrix composite where micron sized particle free aluminide cores (grains) are surrounded by thin mantles comprised of nanometer sized AlN particles and NiAl grains. Under high temperature, slow strain rate conditions both compressive and tensile creep testing have shown that the mechanical strength of hot extruded cryomilled NiAl approaches the levels exhibited by advanced NiAl-based single crystals and simple Ni-based superalloys. Transmission electron microscopy of cryomilled materials tested between 1,100 and 1,300 K revealed little, if any, dislocation structure within the mantle regions, while the NiAl cores contained subgrains and dislocation networks after testing at all strain rates between 10{sup {minus}4} and 10{sup {minus}8} s{sup {minus}1}. These and other microstructural observations suggest that creep strength is the result of a fine NiAl grain/subgrain size, the inability of dislocations to move through the mantle and stabilization of the microstructure by the AlN particles.

  3. Quantum chemical study of the reactions of Al, AlO and AlOH with H2O2

    NASA Astrophysics Data System (ADS)

    Sharipov, Alexander S.; Starik, Alexander M.

    2016-02-01

    Quantum chemical calculations with the use of hybrid density functional with perturbative second-order correlation and dispersion correction are carried out to study the reactions of Al, AlO and AlOH with the H2O2 molecule. The values of energy barriers are estimated by means of extrapolation to the basis set limit. The energetically favorable reaction pathways have been revealed during the examination of the potential energy surfaces. Complex character of the processes under study has been established. It has been found that the initial stages of the considered processes are barrierless. Appropriate rate constants for principal channels of the reactions under study have been estimated by using capture model and canonical variational theory. The Arrhenius approximations for these channels have been proposed for the temperature range T = 300-4000 K.

  4. Reactions of CO2 on solid and liquid Al100+.

    PubMed

    Leslie, Katheryne L; Shinholt, Deven; Jarrold, Martin F

    2013-02-14

    The reactions of CO(2) on the Al(100)(+) cluster have been investigated as a function of cluster temperature (300-1100 K) and relative kinetic energy (0.2-10 eV). Two main products are observed at low cluster temperature: Al(100)O(+) (which is believed to result from a stripping reaction) and Al(100)CO(2)(+) from complex formation. As the cluster temperature is raised, both products dissociate by loss of Al(2)O. Al(100)O(+) forms Al(98)(+), while Al(100)CO(2)(+) forms Al(98)CO(+) and Al(96)C(+). In both cases, loss of Al(2)O turns-on above the melting temperature of Al(100)(+). This presumably occurs because the overall reaction leading to the loss of Al(2)O is significantly less endothermic for the liquid cluster than for the solid. PMID:22680973

  5. Coating of a layer of Au on Al13 : The findings of icosahedral Al@Al12Au20- and Al12Au202- fullerenes using ab initio pseudopotential calculations

    NASA Astrophysics Data System (ADS)

    Kumar, Vijay

    2009-02-01

    We report results of ab initio pseudopotential calculations on the nanocoating of gold on an icosahedral Al13 cluster and the findings of icosahedrally symmetric endohedral Al@Al12Au20- and empty cage Al12Au202- compound fullerenes formed of metal atoms. Twelve Al atoms cap the pentagonal faces of a dodecahedral Au20 cage in which each Au atom has three Al atoms and three Au atoms as nearest neighbors. Mixing of Al13 and Au20 magic clusters leads to a large heat of formation of 0.55 eV/atom and high stability of the Al@Al12Au20 compound fullerene. The binding energies of Al12Au20 and Al@Al12Au20 are 3.017 and 3.007 eV/atom, respectively, which are much larger than 2.457 eV/atom for Au32 fullerene, leading to the possibility of their high abundance.

  6. 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.

  7. Reply to the comments on: ''Series solution of hydromagnetic flow and heat transfer with Hall effect in a second grade fluid over a stretching sheet''

    NASA Astrophysics Data System (ADS)

    Zaman, Haider; Ayub, Muhammad

    2010-06-01

    In this reply to comment on ”Series solution of hydromagnetic flow and heat transfer with Hall effect in a second grade fluid over a stretching sheet” by R. A. Van Gorder and K. Vajravelu manuscript [R. A. Van Gorder, K. Vajravelu, Cent. Eur. J. Phys., DOI:10. 2478/s11534-009-0145-2], we once again claim that the governing similarity equations of Vajravelu and Roper [K. Vajravelu, T. Roper, Int. J. Nonlin. Mech. 34, 1031 (1999)] are incorrect and our claim in [M. Ayub, H. Zaman, M. Ahmad, Cent. Eur. J. Phys. 8, 135 (2010)] is true. For the literature providing justification regarding this issue is discussed in detail.

  8. Reply to the comments on: "Series solution of hydromagnetic flow and heat transfer with Hall effect in a second grade fluid over a stretching sheet"

    NASA Astrophysics Data System (ADS)

    Zaman, Haider; Ayub, Muhammad

    2010-06-01

    In this reply to comment on "Series solution of hydromagnetic flow and heat transfer with Hall effect in a second grade fluid over a stretching sheet" by R. A. Van Gorder and K. Vajravelu manuscript [R. A. Van Gorder, K. Vajravelu, Cent. Eur. J. Phys., DOI:10. 2478/s11534-009-0145-2], we once again claim that the governing similarity equations of Vajravelu and Roper [K. Vajravelu, T. Roper, Int. J. Nonlin. Mech. 34, 1031 (1999)] are incorrect and our claim in [M. Ayub, H. Zaman, M. Ahmad, Cent. Eur. J. Phys. 8, 135 (2010)] is true. For the literature providing justification regarding this issue is discussed in detail.

  9. Basic kinetic wealth-exchange models: common features and open problems

    NASA Astrophysics Data System (ADS)

    Patriarca, M.; Heinsalu, E.; Chakraborti, A.

    2010-01-01

    We review the basic kinetic wealth-exchange models of Angle [J. Angle, Social Forces 65, 293 (1986); J. Math. Sociol. 26, 217 (2002)], Bennati [E. Bennati, Rivista Internazionale di Scienze Economiche e Commerciali 35, 735 (1988)], Chakraborti and Chakrabarti [A. Chakraborti, B. K. Chakrabarti, Eur. Phys. J. B 17, 167 (2000)], and of Dragulescu and Yakovenko [A. Dragulescu, V.M. Yakovenko, Eur. Phys. J. B 17, 723 (2000)]. Analytical fitting forms for the equilibrium wealth distributions are proposed. The influence of heterogeneity is investigated, the appearance of the fat tail in the wealth distribution and the relaxation to equilibrium are discussed. A unified reformulation of the models considered is suggested.

  10. Reply to ‘Comment on “Didactical formulation of the Ampère law”’

    NASA Astrophysics Data System (ADS)

    Barchiesi, Dominique

    2014-09-01

    In this reply to the comment on Barchiesi (2014 Eur. J. Phys. 35 038001) by van Hees, two levels of discussion are proposed. The first is basically related to the teaching of magnetostatic and to the link between the proposed formulation in Barchiesi (2014 Eur. J. Phys. 35 038001) and that in the comment. A solution to the problem without resorting to vector potential, which could be problematic for undergraduates, is proposed to deal with the infinite wire carrying constant current. The second describes the advantages of solving the problem of the wire of finite length, despite the non-conservation charge.

  11. The mechanical properties of FeAl

    SciTech Connect

    Baker, I.; George, E.P.

    1996-12-31

    Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

  12. Boron strengthening in FeAl

    SciTech Connect

    Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C.; Carleton, R.L.; George, E.P.

    1998-11-01

    The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

  13. Primary (AL) amyloidosis in plasma cell disorders.

    PubMed

    Müller, Antonia M S; Geibel, Annette; Neumann, Hartmut P H; Kühnemund, Alexander; Schmitt-Gräff, Annette; Böhm, Joachim; Engelhardt, Monika

    2006-01-01

    Primary (AL) amyloidosis is the most common form of systemic amyloidosis. The morbidity arises from extracellular deposition of immunoglobulin light chain (LC) fibrils in major organs, such as the kidneys, heart, and bowel. Organ dysfunction contributes to a high mortality and poor prognosis, with a median survival time of 1-2 years from diagnosis. Here, we present a 46-year-old man with an exceptional clinical course of an LC multiple myeloma with generalized amyloidosis, causing renal insufficiency, congestive heart failure, and complete intestinal necrosis. We have summarized recent knowledge on AL amyloidosis, its association with monoclonal gammopathies, clinical presentations, diagnostic tools, and treatment strategies. Our comprehensive overview of this rare and often fatal disease aims to increase the awareness of AL amyloidosis. This may facilitate earlier diagnosis, and thus allow initiation of prompt and specific therapies, which are indispensable in order to improve disease prognosis. PMID:16880241

  14. 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.

  15. Adhesion of metal carbide/nitride interfaces: Al/TiC and Al/TiN

    NASA Astrophysics Data System (ADS)

    Liu, L. M.; Wang, S. Q.; Ye, H. Q.

    2003-12-01

    We employ density functional theory to investigate and compare Al/TiC and Al/TiN interfaces by electronic structures, relaxed atomic geometries and adhesions. The results show that the preferred bonding site is the interfacial Al atoms above the ceramic's metalloid atoms for both systems. The calculated adhesion energies are quantitatively in agreement with other calculated and experimental results of Al on the carbide and nitride. A detailed comparison of the adhesion energies and relaxed structures shows weaker bonding and less relaxation in the Al/nitride case, which is correlated with the lower surface energy of the ceramic. We have thoroughly characterized the electronic structure and determined that the polar covalent Al3sp-C(N)2s bonds constitute the primary interfacial bonding interaction. The larger overlapping bonding states at the Al/TiC interface reveal the reason why it exhibits relatively larger adhesion energy. Cleavage may take place preferentially at the interface, especially for the Al/TiN, which is in agreement with experimental results.

  16. 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.

  17. Synthesis of nanostructured AlN by solid state reaction of Al and diaminomaleonitrile

    SciTech Connect

    Rounaghi, S.A.; Eshghi, H.; Kiani Rashid, A.R.; Vahdati Khaki, J.; Samadi Khoshkhoo, M.; Scudino, S.; Eckert, J.

    2013-02-15

    The solid state reaction of diaminomaleonitrile (DAMN) with aluminum via both mechanochemical and thermal treatment routes was studied by X-ray diffraction and Fourier transform infrared spectroscopy. During the milling process, the reaction starts with the deammoniation of the DAMN molecules, followed by the formation of nanostructured AlN powder as the main solid product after milling for 7 h. The reactivity of the mixed powder was also investigated during the conventional thermal treatment process using differential scanning calorimetry, derivative thermogravimetry and thermogravimetric analysis. The results reveal that DAMN starts to polymerize at 192 Degree-Sign C by the elimination of the amine groups. Furthermore, increasing the annealing temperature leads to the formation of a nitrogen-containing carbonaceous material with the structure similar to non-crystalline carbon. However, no evidence for the formation of AlN was observed in the annealed samples even at temperatures as high as the Al melting point. - Graphical abstract: AlN nanoparticles obtained after milling of Al and diaminomaleonitrile (DAMN) for 12 h. Highlights: Black-Right-Pointing-Pointer Solid state reaction of diaminomaleonitrile (DAMN) with Al was studied via mechanochemical and thermal treatment routs. Black-Right-Pointing-Pointer Nanocrystalline AlN was successfully synthesized by the mechanochemical process. Black-Right-Pointing-Pointer The C/N material was formed by polymerization of DAMN during the thermal treatment process. Black-Right-Pointing-Pointer No reaction between DAMN and Al was detected during the thermal treatment method.

  18. 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.

  19. 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.

  20. Disordered crystal structure of 20H-AlON, Al10O3N8

    NASA Astrophysics Data System (ADS)

    Banno, Hiroki; Funahashi, Shiro; Asaka, Toru; Hirosaki, Naoto; Fukuda, Koichiro

    2015-10-01

    The disordered crystal structure of 20H-AlON (Al10O3N8) was determined by combined use of X-ray powder diffraction and transmission electron microscopy. The title compound is hexagonal with space group P63/mmc (Z=2) and the unit-cell dimensions are a=0.307082(5) nm, c=5.29447(8) nm and V=0.432376(12) nm3. The structural model showed the positional disordering of three of the six Al sites in the unit cell. The reliability indices calculated from the Rietveld method were Rwp=6.97%, S (=Rwp/Re)=1.68, Rp=5.45%, RB=5.13% and RF=4.56%. We interpreted the disordered structure of 20H-AlON as a statistical average of six different types of ordered structural configurations, which are composed of an octahedral [Al(O, N)6] layer and tetrahedral [Al(O, N)4] layers. We demonstrated the high correlations between the hexagonal unit-cell dimensions and the octahedral layer concentrations for AlON and SiAlON polytypoids.

  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. Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys

    NASA Astrophysics Data System (ADS)

    Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

    2014-09-01

    This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

  3. 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. PMID:26993281

  4. The ALS Storage Ring RF System

    SciTech Connect

    Taylor, B.; Lo, C.C.; Baptiste, K.; Guigli, J.; Julian, J.

    1993-05-01

    The ALS Storage Ring RF System is characterized by the use of the following features: (1) High power loading of two single cell cavities. (2) The use of a tubular ceramic input window employing aperture coupling. (3) The use of waveguide filters and matchers designed for HOM absorption. (4) A comprehensive HOM monitoring system. (5) The use of waveguide water-wedge loads for the magic tee and circulator loads. The results of cavity measurements and high power tests are reported together with the performance of the system during the commissioning and operation phases of the ALS project. Plans for future window development are discussed.

  5. Quadrupole scattering in PrAl2

    NASA Astrophysics Data System (ADS)

    Sablik, M. J.; Pureur, P.; Creuzet, G.; Fert, A.; Levy, P. M.

    1983-10-01

    We derive the spontaneous anisotropy of the resistivity of the ferromagnetic compound PrAl2 from magnetoresistance measurements on a single crystal of PrAl2. We ascribe this spontaneous anisotropy of the resistivity to scattering of the conduction electrons by the thermal quadrupole disorder and we account for our experimental results by using the theoretical model previously developed by us. We find that quadrupole scattering gives a very important contribution to the total magnetic disorder (spin and quadrupole) resistivity but that only a small part of this quadrupole contribution is anisotropic.

  6. Nb3Al Development for HEP Applications

    SciTech Connect

    Sumption, M.D.; Buta, F.; Collings, E.W.; Tomsic, M.; Phillips, J.; McFadden, K.; Wu, X

    2004-06-28

    Recent developments in Nb3Al strand for HEP applications are presented and discussed. The present state of available precursor is detailed. Two routes have been shown to lead to successful construction of MF NbAl composite wires. An extrusion method has so far produced the highest filament counts and smallest filament diameters, but requires more processing steps. A direct restack and draw approach has also been demonstrated which minimizes the number of processing steps while still leading to a high performance conductor. This latter route also allows for a lower cost per billet, potentially allowing the exploration of more process parameters.

  7. 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

  8. Dynamical DMRG study of non-linear optical response in one-dimensional dimerized Hubbard model with nearest neighbor Coulomb interaction and alternating on-site potential

    NASA Astrophysics Data System (ADS)

    Sota, Shigetoshi; Tohyama, Takami; Brazovskii, Serguei

    2012-02-01

    The optical response of organic compounds has been attracting much attention. The one of the reasons is the huge non-linear and ultrafast optical response [K. Yamamoto et. al., J. Phys. Soc. Jpn. 77, 074709(2008)]. In order to investigate such optical properties, we carry out dynamical DMRG calculations to obtain optical responses in the 1/4-filled one-dimensional Hubbard model including the nearest neighbor Coulomb interaction and the alternating electron hopping. The charge gap [S. Nishimoto, M. Takahashi, and Y. Ohta, J. Phys. Soc. Jpn. 69, 1594(2000)] and the bound state [H. Benthien and E. Jeckelmann, Eur. Phys. J. B 44, 287(2005)] in this model have been discussed based on DMRG calculations. In the present study, we introduce an alternating on-site potential giving the polarization in the system into the dimerized Hubbard model, which breaks the reflection symmetry of the system. In this talk, we discuss the obtained linear and the 2nd order non-linear optical susceptibility in order to make a prediction for non-linear optical experiments in the future.

  9. Surface phonon polariton characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure.

    PubMed

    Ng, S S; Lee, S C; Bakhori, S K Mohd; Hassan, Z; Abu Hassan, H; Yakovlev, V A; Novikova, N N; Vinogradov, E A

    2010-05-10

    Surface phonon polariton (SPP) characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure are investigated by means of p-polarized infrared (IR) attenuated total reflection spectroscopy. Two absorption dips corresponding to In(0.04)Al(0.06)Ga(0.90)N SPP modes are observed. In addition, two prominent dips and one relatively weak and broad dip corresponding to the Al(2)O(3) SPP mode, In(0.04)Al(0.06)Ga(0.90)N/Al(2)O(3) interface mode, and Al(2)O(3) bulk polariton mode, respectively, are clearly seen. No surface mode feature originating from the AlN layer is observed because it is too thin. Overall, the observations are in good agreement with the theoretical predictions. PMID:20588890

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. In situ microscopy of rapidly heated nano-Al and nano-Al/WO3 thermites

    NASA Astrophysics Data System (ADS)

    Sullivan, Kyle T.; Chiou, Wen-An; Fiore, Richard; Zachariah, Michael R.

    2010-09-01

    The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 106 K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.

  15. Preparation, structure and mechanical properties of RuAl and (Ru,Ni)Al alloys

    SciTech Connect

    Sabariz, A.L.R.; Taylor, G.

    1997-12-31

    The intermetallic compound, RuAl with B2 CsCl type structure, has been shown to possess room-temperature toughness and plasticity. NiAl also forms a B2 compound and it is claimed that a pseudo-binary compound, (Ru,Ni)Al, may be formed because the difference in lattice parameter between the two binary phases is slight. In this work a study has been made of the mechanical properties of some polycrystalline compounds, across the RuAl-(Ru,Ni)Al pseudo-binary, prepared from high-purity elemental powders. Compressive yield stresses were measured between room-temperature and 900 C, and the mechanisms of plastic flow are discussed in relation to the dislocation structures observed by TEM. Hot-microhardness tests were made to provide an indication of the effect of solid-solution hardening.

  16. 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.

  17. 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.

  18. 26Al+p elastic and inelastic scattering reactions and galactic abundances of 26Al

    NASA Astrophysics Data System (ADS)

    Pittman, S. T.; Bardayan, D. W.; Chae, K. Y.; Chipps, K. A.; Jones, K. L.; Kozub, R. L.; Matei, C.; Matos, M.; Moazen, B. H.; Nesaraja, C. D.; O'Malley, P. D.; Pain, S. D.; Parker, P. D.; Peters, W. A.; Shriner, J. F., Jr.; Smith, M. S.

    2012-06-01

    Galactic 26Al is the first radioactive nucleus to be positively identified by γ-ray astronomy with detection of the 1.809 MeV γ ray associated with its decay. This nucleus is destroyed in astrophysical environments in the 26Al(p,γ)27Si and inelastic 26Al+p scattering reactions where properties of 27Si levels determine reaction rates. To investigate these properties, elastic and inelastic 26Al+p scattering reactions were measured between Ec.m. = 0.5-1.5 MeV at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). A candidate for a new resonance in the 26Al(p,γ)27Si reaction was identified. Upper limits were also set on the strengths of postulated resonances and on the cross section of the inelastic reaction, but there is little effect on current reaction rate calculations.

  19. Effect of stress on the Al composition evolution in AlGaN grown using metal organic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    He, Chenguang; Qin, Zhixin; Xu, Fujun; Zhang, Lisheng; Wang, Jiaming; Hou, Mengjun; Zhang, Shan; Wang, Xinqiang; Ge, Weikun; Shen, Bo

    2016-05-01

    Two series of AlGaN samples with different stresses were designed to investigate the effect of stress on the Al composition. X-ray diffraction reciprocal space mapping (XRD RSM) demonstrated that the AlGaN epilayers with different stresses have large Al composition differences despite the same growth conditions. The largest Al composition difference reached up to 21.3%, which was also confirmed using secondary ion mass spectroscopy (SIMS). This result is attributed to a large stress discrepancy in the AlGaN epilayers. Finally, the dependences of the solid-phase Al composition on the gas-phase Al composition under different stresses were systematically analyzed.

  20. Equilibrium point defects in intermetallics with the [ital B]2 structure: NiAl and FeAl

    SciTech Connect

    Fu, C.L.; Ye, Y.; Yoo, M.H. ); Ho, K.M. )

    1993-09-01

    Equilibrium point defects and their relation to the contrasting mechanical behavior of NiAl and FeAl are investigated. For NiAl, the defect structure is dominated by two types of defects---monovacancies on the Ni sites and substitutional antisite defects on the Al sites. The defect structure of FeAl differs from that of NiAl in the occurrence of antisite defects at the transition-metal sites for Al-rich alloys and the tendency for vacancy clustering. The strong ordering (and brittleness) of NiAl is attributed mainly to the difference in atomic size between constituent atoms.