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Sample records for al excitation function

  1. Cross-Correlation of Excitation Functions for Different Fragments and Different Scattering Angles in 27Al(19F, x) y Reactions

    Institute of Scientific and Technical Information of China (English)

    HAN Jian-Long; WU He-Yu; LI Zhi-Chang; LU Xiu-Qin; ZHAO Kui; ZHOU Ping; LIU Jian-Cheng; XU Guo-Ji; Sergey Yu Kun; WANG Qi; BAI Zhen; DONG Yu-Chuan; LI Song-Lin; DUAN Li-Min; XU Hu-Shan; XU Hua-Gen; CHEN Ruo-Fu

    2008-01-01

    @@ Excitation functions have been measured for different projectile-like fragments produced in 27 Al(19 F,x)y reactions at incident energies from 110.25 to 118. 75 Me V in 250 ke V steps. Strong cross section fluctuations of the excitation functions are observed. The cross-correlation coefficients of the excitation functions for different atomic number Z and for different scattering angle θcm have been deduced. These coefficients are much larger than the statistical theoretical calculated ones. This indicates that there are strong correlations between different exit channels in the dissipative heavy ion collision of 27 Al(19 F,x )y.

  2. Nuclear excitation functions of proton-induced reactions (Ep = 35-90 MeV) from Fe, Cu, and Al

    Science.gov (United States)

    Graves, Stephen A.; Ellison, Paul A.; Barnhart, Todd E.; Valdovinos, Hector F.; Birnbaum, Eva R.; Nortier, Francois M.; Nickles, Robert J.; Engle, Jonathan W.

    2016-11-01

    Fe, Cu, and Al stacked foils were irradiated by 90 MeV protons at the Los Alamos Neutron Science Center's Isotope Production Facility to measure nuclear cross sections for the production of medically relevant isotopes, such as 52gMn, 54Mn, 48Cr, 55Co, 58mCo and 57Ni. The decay of radioactive isotopes produced during irradiation was monitored using high-purity germanium gamma spectroscopy over the months following irradiation. Proton fluence was determined using the natAl(p,x)22Na, natCu(p,x)62Zn natCu(p,x)65Zn, and natCu(p,x)56Co monitor reactions. Calculated cross sections were compared against literature values and theoretical TALYS predictions. Notably this work includes the first reported independent cross section measurements of natCu(p,x)58mCo and natCu(p,x)58gCo.

  3. Precise measurement of the sup 2 sup 7 Al(n,2n) sup 2 sup 6 sup g Al excitation function near threshold and its relevance for fusion-plasma technology

    CERN Document Server

    Wallner, A; Priller, A; Steier, P; Vonach, H; Chuvaev, S V; Filatenkov, A A; Ikeda, Y; Mertens, G; Rochow, W

    2003-01-01

    A new accurate measurement of the sup 2 sup 7 Al(n,2n) sup 2 sup 6 Al excitation function leading to the ground state of sup 2 sup 6 Al(t sub 1 sub / sub 2 =7.1 x 10 sup 5 years) in the near-threshold region (E sub t sub h =13.55 MeV) was performed, with the goal to achieve relative cross-sections with the highest accuracy possible using proven methods. In addition, the measurements were also designed to provide good absolute cross-section values, since absolute cross-sections are important for radioactive waste predictions in future fusion reactor materials. Samples of Al metal were irradiated with neutrons in the energy range near threshold (E sub n =13.5-14.8 MeV) in Vienna and St. Petersburg, and at 14.8 MeV in Tokai-mura. In addition, irradiations with neutrons of higher energies (17 and 19 MeV) were performed in Tuebingen, to obtain also cross-section values well above threshold. The amount of sup 2 sup 6 Al produced during the irradiations was measured via accelerator mass spectrometry (AMS). With this...

  4. Impedimetric Sensing Proprieties of ITO Electrodes Functionalized with PEDOT:PSS/Azo-Calix[4]Arene for the Detection of Al3+ Ions Under Light Excitation

    Science.gov (United States)

    Echabaane, M.; Rouis, A.; Mahjoub, M. A.; Bonnamour, I.; Ben Ouada, H.

    2017-01-01

    This study describes an investigation of the sensitivity of the azo-calix[4]arene/poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS) thin film deposited on the indium tin oxide (ITO) electrode surface toward aluminum ions (Al3+) under light excitation. Thin films were deposited by the spin-coating technique. Adhesion of these films to the ITO surface was highlighted by performing contact angle measurements. Then, interfaces of the azo-calix[4]arene/PEDOT:PSS thin film were characterized by impedance measurements using electrochemical impedance spectroscopy. Obtained impedance spectra were fitted using an equivalent circuit. Finally, evolutions of the different components of this circuit were studied. These evolutions show that the sensitivity of the azo-calix[4]arene/PEDOT:PSS/ITO electrode is remarkably improved under illumination.

  5. Impedimetric Sensing Proprieties of ITO Electrodes Functionalized with PEDOT:PSS/Azo-Calix[4]Arene for the Detection of Al3+ Ions Under Light Excitation

    Science.gov (United States)

    Echabaane, M.; Rouis, A.; Mahjoub, M. A.; Bonnamour, I.; Ben Ouada, H.

    2016-08-01

    This study describes an investigation of the sensitivity of the azo-calix[4]arene/poly(3,4-ethylenedioxythiophene)/poly-(styrenesulfonate) (PEDOT:PSS) thin film deposited on the indium tin oxide (ITO) electrode surface toward aluminum ions (Al3+) under light excitation. Thin films were deposited by the spin-coating technique. Adhesion of these films to the ITO surface was highlighted by performing contact angle measurements. Then, interfaces of the azo-calix[4]arene/PEDOT:PSS thin film were characterized by impedance measurements using electrochemical impedance spectroscopy. Obtained impedance spectra were fitted using an equivalent circuit. Finally, evolutions of the different components of this circuit were studied. These evolutions show that the sensitivity of the azo-calix[4]arene/PEDOT:PSS/ITO electrode is remarkably improved under illumination.

  6. Pressure dependence of donor excitation spectra in AlSb

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, L.; McCluskey, M.D.; Haller, E.E.

    2002-01-16

    We have investigated the behavior of ground to bound excited-state electronic transitions of Se and Te donors in AlSb as a function of hydrostatic pressure. Using broadband far-infrared Fourier transform spectroscopy, we observe qualitatively different behaviors of the electronic transition energies of the two donors. While the pressure derivative of the Te transition energy is small and constant, as might be expected for a shallow donor, the pressure derivatives of the Se transition energies are quadratic and large at low pressures, indicating that Se is actually a deep donor. In addition, at pressures between 30 and 50 kbar, we observe evidence of an anti-crossing between one of the selenium electronic transitions and a two-phonon mode.

  7. Evaluation of Excitation Function for 64Zn

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Present work concerns the evaluated neutron induced excitation function data for 64Zn, and mainly on (n, γ) reaction channel. The related experimental data were collected, analyzed and corrected for 64Zn

  8. Evaluation of Excitation Function for 182Ta

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Present work concerns the evaluated neutron induced excitation function data for 182Ta, and mainly on (n, γ) reaction channel. The related experimental data were collected, analyzed and corrected for 182Ta

  9. Excitation functions for the production of radionuclides by neutron-induced reactions on C, O, Mg, Al, Si, Fe, Co, Ni, Cu, Ag, Te, Pb, and U up to 180 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Michel, R., E-mail: michel@irs.uni-hannover.de [Institute for Radioecology and Radiological Protection, Leibniz University Hannover (Germany); Hansmann, D. [Institute for Radioecology and Radiological Protection, Leibniz University Hannover (Germany); Neumann, S. [Institute for Radioecology and Radiological Protection, Leibniz University Hannover (Germany); Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Glasser, W. [Institute for Radioecology and Radiological Protection, Leibniz University Hannover (Germany); Schuhmacher, H.; Dangendorf, V.; Nolte, R. [Physikalisch-Technische Bundesanstalt (PTB), Braunschweig (Germany); Herpers, U. [Dept. for Nuclear Chemistry, University of Cologne (Germany); Smirnov, A.N.; Ryzhov, I.V. [V. G. Khlopin Radium Institute, St. Petersburg (Russian Federation); Prokofiev, A.V. [The Svedberg Laboratory (TSL), Uppsala University (Sweden); Dept. of Physics and Astronomy, Uppsala University (Sweden); Malmborg, P. [The Svedberg Laboratory (TSL), Uppsala University (Sweden); Kollár, D. [Dept. of Nuclear Physics, Comenius University, Bratislava (Slovakia); Meulders, J.-P. [Université Catholique de Louvain (UCL), Louvain-la-Neuve (Belgium)

    2015-01-15

    Irradiation experiments with well-characterized, quasi mono-energetic neutrons of energies between 32.7 MeV and 175.4 MeV were performed at UCL/Louvain-la-Neuve and TSL/Uppsala. The abundances of relatively short-lived residual radionuclides from 13 different target elements were determined by γ-spectrometry. More than 100 excitation functions of neutron-induced reactions were unfolded based on the neutron spectra and the radionuclide abundances with the aid of additional information that was provided by “guess” excitation functions calculated by the TALYS 1.0 code. The results are compared with the sparse existing data from other authors. The new excitation functions were validated by calculation of and comparison with experimental thick-target production rates. Consistency with neutron excitation functions up to 1.6 GeV, which were derived earlier by unfolding the thick-target production rates, was so demonstrated.

  10. Fusion excitation functions involving transitional nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others

    1995-08-01

    Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.

  11. Statistical property of the Chandler wobble excitation function

    Institute of Scientific and Technical Information of China (English)

    LIAO Dechun; LIAO Xinhao; ZHOU Yonghong

    2004-01-01

    The Chandler wobble excitation function (hereinafter, geodetic excitation) is obtained by removing the seasonal components and low frequency components with periods from several years to decades from the polar motion excitation function derived from SPACE2002 series. The geophysical excitation functions of the individual AAM, OAM, HAM, and two combined excitations of the AAM + OAM and AAM + OAM + HAM at 1d, 5d, 1m and 3m intervals are statistically tested for the hypothesis of the normality, and then tested for the hypotheses of identical distribution between the geodetic and the geophysical excitations. The results show that, among the total 16 components of the two combined excitation functions at 1d, 5d, 1m and 3m intervals,most follow random normal processes, the hypotheses of identical distribution between the geodetic excitation and the two combined excitation are acceptable, while most of the hypotheses of identical distribution between the geodetic excitation and the individual excitations of the AAM, OAM, and HAM are rejectable.These results elucidate from a new point of view, that the excitations from AAM, OAM, and HAM are the main sources of the Chandler wobble, and the Chandler wobble excitation function is of a random normal property.

  12. Highly excited strings I: Generating function

    Directory of Open Access Journals (Sweden)

    Dimitri P. Skliros

    2017-03-01

    Full Text Available This is the first of a series of detailed papers on string amplitudes with highly excited strings (HES. In the present paper we construct a generating function for string amplitudes with generic HES vertex operators using a fixed-loop momentum formalism. We generalise the proof of the chiral splitting theorem of D'Hoker and Phong to string amplitudes with arbitrary HES vertex operators (with generic KK and winding charges, polarisation tensors and oscillators in general toroidal compactifications E=RD−1,1×TDcr−D (with generic constant Kähler and complex structure target space moduli, background Kaluza–Klein (KK gauge fields and torsion. We adopt a novel approach that does not rely on a “reverse engineering” method to make explicit the loop momenta, thus avoiding a certain ambiguity pointed out in a recent paper by Sen, while also keeping the genus of the worldsheet generic. This approach will also be useful in discussions of quantum gravity and in particular in relation to black holes in string theory, non-locality and breakdown of local effective field theory, as well as in discussions of cosmic superstrings and their phenomenological relevance. We also discuss the manifestation of wave/particle (or rather wave/string duality in string theory.

  13. Highly excited strings I: Generating function

    Science.gov (United States)

    Skliros, Dimitri P.; Copeland, Edmund J.; Saffin, Paul M.

    2017-03-01

    This is the first of a series of detailed papers on string amplitudes with highly excited strings (HES). In the present paper we construct a generating function for string amplitudes with generic HES vertex operators using a fixed-loop momentum formalism. We generalise the proof of the chiral splitting theorem of D'Hoker and Phong to string amplitudes with arbitrary HES vertex operators (with generic KK and winding charges, polarisation tensors and oscillators) in general toroidal compactifications E =R D - 1 , 1 ×T Dcr - D (with generic constant Kähler and complex structure target space moduli, background Kaluza-Klein (KK) gauge fields and torsion). We adopt a novel approach that does not rely on a ;reverse engineering; method to make explicit the loop momenta, thus avoiding a certain ambiguity pointed out in a recent paper by Sen, while also keeping the genus of the worldsheet generic. This approach will also be useful in discussions of quantum gravity and in particular in relation to black holes in string theory, non-locality and breakdown of local effective field theory, as well as in discussions of cosmic superstrings and their phenomenological relevance. We also discuss the manifestation of wave/particle (or rather wave/string) duality in string theory.

  14. Highly Excited Strings I: Generating Function

    CERN Document Server

    Skliros, Dimitri P; Saffin, Paul M

    2016-01-01

    This is the first of a series of detailed papers on string amplitudes with highly excited strings (HES). In the present paper we construct a generating function for string amplitudes with generic HES vertex operators using a fixed-loop momentum formalism. We generalise the proof of the chiral splitting theorem of D'Hoker and Phong to string amplitudes with arbitrary HES vertex operators (with generic KK and winding charges, polarisation tensors and oscillators) in general toroidal compactifications $\\mathcal{E}=\\mathbb{R}^{D-1,1}\\times \\mathbb{T}^{D_{\\rm cr}-D}$ (with generic constant K\\"ahler and complex structure target space moduli, background Kaluza-Klein (KK) gauge fields and torsion). We adopt a novel approach that does not rely on a "reverse engineering" method to make explicit the loop momenta, thus avoiding a certain ambiguity pointed out in a recent paper by Sen, while also keeping the genus of the worldsheet generic. This approach will also be useful in discussions of quantum gravity and in particu...

  15. Functional Integrals and Collective Excitations in Boson-Fermion Model

    Institute of Scientific and Technical Information of China (English)

    YAN Jun

    2006-01-01

    In this paper, collective excitations in the boson-fermion model are investigated by means of functional integration method. The equations of energy gap and excitation spectrum are derived. Moreover, the Bose energy spectrum of zero wave vector Fermi fields is also calculated.

  16. Exact ensemble density-functional theory for excited states

    CERN Document Server

    Yang, Zeng-hui; Pribram-Jones, Aurora; Burke, Kieron; Needs, Richard J; Ullrich, Carsten A

    2014-01-01

    We construct exact Kohn-Sham potentials for the ensemble density-functional theory (EDFT) of excited states from the ground and excited states of helium. The exchange-correlation potential is compared with current approximations, which miss prominent features. The ensemble derivative discontinuity is tested, and the virial theorem is proven and illustrated.

  17. Melting of Al Induced by Laser Excitation of 2p Holes

    OpenAIRE

    Rosandi, Y.; Cheenicode Kabeer, F.; Cherednikov, Y.; Zijlstra, E.; Garcia, M; Inogamov, N.; Urbassek, H.

    2015-01-01

    Novel photon sources—such as XUV- or X-ray lasers—allow to selectively excite core excitations in materials. We study the response of a simple metal, Al, to the excitation of 2p holes using molecular dynamics simulations. During the lifetime of the holes, the interatomic interactions in the slab are changed; we calculate these using WIEN2k. We find that the melting dynamics after core-hole excitation is dominated by classical electron–phonon dynamics. The effects of the changed potential surf...

  18. Excitation Spectra of Nucleobases with Multiconfigurational Density Functional Theory

    DEFF Research Database (Denmark)

    Hubert, Mickaël; Jensen, Hans Jørgen Aa; Hedegård, Erik D.

    2016-01-01

    Range-separated hybrid methods between wave function theory and density functional theory (DFT) can provide high-accuracy results, while correcting some of the inherent flaws of both the underlying wave function theory and DFT. We here assess the accuracy for excitation energies of the nucleobases...

  19. Nuclear reaction excitation functions in the interaction of protons with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gonchar, A.V.; Kondratyev, S.N.; Lobach, Yo.N.; Sklyarenko, V.D.; Tokarevsky, V.V.; Vysotsky, O.N. (AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Yadernykh Issledovanij)

    1993-12-01

    Nuclear reaction excitation functions have been investigated which result in radioactive and stable nuclide formation following the proton bombardment of silicon with proton energies up to 100 MeV. Summarized experimental data and excitation function calculations have been performed regarding the mechanisms of pre-equilibrium emission and evaporation from compound nuclides based on the ALICE LIVERMORE code. With the aim of nuclear doping, transmutation coefficients for Al, Mg and Na have been calculated as well as the [gamma]-ray activities of the doped material. (Author).

  20. AlN-based piezoelectric bimorph microgenerator utilizing low-level non-resonant excitation

    Science.gov (United States)

    Hampl, Stefan; Cimalla, Volker; Polster, Tobias; Hoffmann, Martin

    2011-06-01

    This work aims for utilizing human ocular motion for the self-sufficient power supply of a minimally invasive implantable monitoring system for intraocular pressure (IOP). With a proven piezoelectric functionality (d33>5 pm/V), nanocrystalline thin films of aluminum nitride (AlN) provide a good capability for micromechanical energy harvesting (EH) in medical applications. Many d31-mode microcantilever architectures are poorly suited for human-induced EH: Resonant mass-spring-damper systems are tested under high, narrow-band excitation frequencies. However, human motions, e.g. vibrations of eyeballs are marked by their low frequency, unpredictable, mainly aperiodic and time-varying signature. Different vibration types and directions are 3-dimensionally superimposed. Saccadic eye movements are favorable for inertial microgenerators because of their high dynamic loading (ω<=1000°/s). Our generator concept (symmetric active/active-parallel-bimorph cantilever) enables a high structural compliance by maximizing the piezoactive volume at very low cantilever thicknesses (<1 μm). An increased length and seismic mass enable an effective excitation by low-level aperiodic vibrations such as saccadic acceleration impulses. Analytic calculations and FEA-simulations investigate the potential distribution and transient response of different bimorph structures (length 200- 1000 μm, width 20-200 μm) on broadband vibrations. First released monomorph and bimorph structures show very low resonant frequencies and an adequate robustness.

  1. Thick-target transmission method for excitation functions of interaction cross sections

    CERN Document Server

    Aikawa, M; Imai, S

    2016-01-01

    We propose a method, called as thick-target transmission (T3) method, to obtain an excitation function of interaction cross sections. In an ordinal experiment to measure the excitation function of interaction cross sections by the transmission method, we need to change the beam energy for each cross section. In the T3 method, the excitation function is derived from the beam attenuations measured at the targets of different thicknesses without changing the beam energy. The advantage of the T3 method is the simplicity and availability for radioactive beams. To confirm the availability, we perform a simulation for the 12C+27Al system with the PHITS code instead of actual experiments. Our results have large uncertainties but well reproduce the tendency of the experimental data.

  2. Excitations and benchmark ensemble density functional theory for two electrons

    CERN Document Server

    Pribram-Jones, Aurora; Trail, John R; Burke, Kieron; Needs, Richard J; Ullrich, Carsten A

    2014-01-01

    A new method for extracting ensemble Kohn-Sham potentials from accurate excited state densities is applied to a variety of two electron systems, exploring the behavior of exact ensemble density functional theory. The issue of separating the Hartree energy and the choice of degenerate eigenstates is explored. A new approximation, spin eigenstate Hartree-exchange (SEHX), is derived. Exact conditions that are proven include the signs of the correlation energy components, the virial theorem for both exchange and correlation, and the asymptotic behavior of the potential for small weights of the excited states. Many energy components are given as a function of the weights for two electrons in a one-dimensional flat box, in a box with a large barrier to create charge transfer excitations, in a three-dimensional harmonic well (Hooke's atom), and for the He atom singlet-triplet ensemble, singlet-triplet-singlet ensemble, and triplet bi-ensemble.

  3. Resonant indirect excitation of Gd{sup 3+} in AlN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ishizu, Yuta; Tsuji, Kazuma; Harada, Yukihiro; Kita, Takashi [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan); Chigi, Yoshitaka; Nishimoto, Tetsuro; Tanaka, Hiroyuki; Kobayashi, Mikihiro [YUMEX INC., 400 Itoda, Yumesaki, Himeji, Hyogo 671-2114 (Japan); Ishihara, Tsuguo; Izumi, Hirokazu [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira, Suma, Kobe 654-0037 (Japan)

    2014-05-07

    We studied the efficient indirect excitation of Gd{sup 3+} ions in AlN thin films. C-axis oriented polycrystalline thin films of Al{sub 0.997}Gd{sub 0.003}N/AlN were grown on fused silica substrates using a reactive radio-frequency magnetron sputtering technique. The intra-orbital electron transition in Gd{sup 3+} showed a narrow luminescence line at 3.9 eV. The photoluminescence (PL) excitation (PLE) spectrum exhibited a peak originating from efficient indirect energy transfer from the band edge of AlN to Gd{sup 3+} ions. The PLE peak shifted and the PL intensity showed a dramatic change when the AlN band gap was varied by changing the temperature. Energy scanning performed by changing the band-gap energy of AlN with temperature revealed several resonant channels of energy transfer into the higher excited states of Gd{sup 3+}.

  4. Band Excitation in Scanning Probe Microscopy: Recognition and Functional Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jesse, Stephen [ORNL; Vasudevan, Dr. Rama [Oak Ridge National Laboratory (ORNL); Collins, Liam [University College, Dublin; Strelcov, Evgheni [ORNL; Okatan, Mahmut B [ORNL; Belianinov, Alex [ORNL; Baddorf, Arthur P [ORNL; Proksch, Roger [Asylum Research, Santa Barbara, CA; Kalinin, Sergei V [ORNL

    2014-01-01

    Field confinement at the junction between a biased scanning probe microscope s (SPM) tip and solid surface enables local probing of various bias-induced transformations such as polarization switching, ionic motion, or electrochemical reactions to name a few. The nanoscale size of the biased region is smaller or comparable to features like grain boundaries and dislocations, potentially allows for the study of kinetics and thermodynamics at the level of a single defect. In contrast to classical statistically averaged approaches, this allows one to link structure to functionality and deterministically decipher associated mesoscopic and atomistic mechanisms. Furthermore, this type of information can serve as a fingerprint of local material functionality, allowing for local recognition imaging. Here, current progress in multidimensional SPM techniques based on band-excitation time and voltage spectroscopies is illustrated, including discussions on data acquisition, dimensionality reduction, and visualization along with future challenges and opportunities for the field.

  5. Cryptanalysis of Lin et al.'s Efficient Block-Cipher-Based Hash Function

    NARCIS (Netherlands)

    Liu, Bozhong; Gong, Zheng; Chen, Xiaohong; Qiu, Weidong; Zheng, Dong

    2010-01-01

    Hash functions are widely used in authentication. In this paper, the security of Lin et al.'s efficient block-cipher-based hash function is reviewed. By using Joux's multicollisions and Kelsey et al.'s expandable message techniques, we find the scheme is vulnerable to collision, preimage and second

  6. Excitation function calculations for α + 93Nb nuclear reactions

    Science.gov (United States)

    Yiğit, M.; Tel, E.; Sarpün, İ. H.

    2016-10-01

    In this study, the excitation functions of alpha-induced reactions on the 93Nb target nucleus were calculated by using ALICE-ASH code. The hybrid model, Weisskopf-Ewing model and geometry dependent hybrid model in this code were used to understand the alpha-niobium interaction. The contribution on the nuclear interaction of compound and pre-compound processes, with variation of the incident alpha particle energy, was presented. Furthermore, the reaction cross sections were calculated by using different level density models such as Superfluid nuclear model, Fermi gas model and Kataria-Ramamurthy Fermi gas model. Obtaining a good agreement between the calculated and the measured cross sections, the exciton numbers and the nuclear level density models were varied. Finally, the proper choice of the exciton numbers and the nuclear level density models was found to be quite important in order to obtain the more realistic cross section values.

  7. Gamma-ray strength functions in thermally excited rotating nuclei

    CERN Document Server

    Døssing, T; Maj, A; Matsuo, M; Vigezzi, E; Bracco, A; Leoni, S; Broglia, R A

    2001-01-01

    A general discussion and illustration is given of strength functions for rotational transitions in two-dimensional E(gamma_1) x E(gamma_2) spectra. Especially, a narrow component should be proportional to the compound damping width, related to the mixing of basis rotational bands into compound bands with fragmented transition strength. Three E(gamma_1) x E(gamma_2) spectra are made by setting gates on triple coincidences, selecting cascades which feed into specific low-lying bands in the nucleus 168Hf. In each of the gated spectra, we find a ridge, carrying about 100 decay paths. This ridge is ascribed to rotational transitions in the excitation energy range of 1.0 to 1.5 MeV above the yrast line. The FWHM of the ridges are around 40 keV, about a factor of two smaller than calculated on the basis of mixed cranked mean field bands.

  8. Functional Assessment of Corticospinal System Excitability in Karate Athletes.

    Directory of Open Access Journals (Sweden)

    Fiorenzo Moscatelli

    Full Text Available To investigate the involvement of the primary motor cortex (M1 in the coordination performance of karate athletes through transcranial magnetic stimulation (TMS.Thirteen right-handed male karate athletes (25.0±5.0 years and 13 matched non-athlete controls (26.7±6.2 years were enrolled. A single-pulse TMS was applied using a figure-eight coil stimulator. Resting motor threshold (rMT was determined. Surface electromyography was recorded from the first dorsal interosseous muscle. Motor evoked potential (MEP latencies and amplitudes at rMT, 110%, and 120% of rMT were considered. Functional assessment of the coordination performance was assessed by in-phase (IP and anti-phase (AP homolateral hand and foot coordination tasks performed at 80, 120, and 180 bpm.Compared to controls, athletes showed lower rMT (p<0.01, shorter MEP latency (p<0.01 and higher MEP amplitude (p<0.01, with a significant correlation (r = 0.50, p<0.01 between rMT and MEP latency. Coordination decreased with increasing velocity, and better IP performances emerged compared to AP ones (p<0.001. In general, a high correlation between rMT and coordination tasks was found for both IP and AP conditions.With respect to controls, karate athletes present a higher corticospinal excitability indicating the presence of an activity-dependent alteration in the balance and interactions between inhibitory and facilitatory circuits determining the final output from the M1. Furthermore, the high correlation between corticospinal excitability and coordination performance could support sport-specific neurophysiological arrangements.

  9. Excitations

    Energy Technology Data Exchange (ETDEWEB)

    Dorner, B. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1996-12-31

    A short introduction to instrumental resolution is followed by a discussion of visibilities of phonon modes due to their eigenvectors. High precision phonon dispersion curves in GaAs are presented together with `ab initio` calculations. Al{sub 2}O{sub 3} is taken as an example of selected visibility due to group theory. By careful determination of phonon intensities eigenvectors can be determined, such as in Silicon and Diamond. The investigation of magnon modes is shown for the garnet Fe{sub 2}Ca{sub 3}(GeO{sub 4}){sub 3}, where also a quantum gap due to zero point spin fluctuations was observed. The study of the splitting of excitons in CsFeCl{sub 3} in an applied magnetic field demonstrates the possibilities of neutron polarisation analysis, which made it possible to observe a mode crossing. An outlook to inelastic X-ray scattering with very high energy resolution of synchrotron radiation is given with the examples of phonons in Beryllium and in water. (author) 19 figs., 36 refs.

  10. Is There a Linear Building Transfer Function for Small Excitation?

    Science.gov (United States)

    Clinton, J. F.; Heaton, T. H.

    2003-12-01

    In the absence of actual building accelerometer data, the linear response of a structure to strong ground motion is estimated by the convolution of the dynamic response of the structure with an input ground motion. The input motion is usually provided by a local `reference' station record. In this study, we look at whether actual recorded ground motion at two instrumented buildings with well studied dynamic properties can be satisfactorily modeled using a local ground station. All stations record continuous 24-bit data streams on the CISN network, so analysis of a variety of weak earthquake motions, as well as ambient noise, is possible. Our buildings are the 9-story reinforced concrete Millikan Library (CISN Station MIK) and the 3-story braced steel frame Broad Center (CBC), both on the Caltech Campus. Motions recorded on their upper floors are compared with motions from ground stations located in the basement of a lightweight wood-frame house (GSA), and in a subsurface vault (CRP). All stations are within 200m of each other. Recent work using the new continuous datastream indicates that the natural frequencies of these structures can vary by up to 5% during normal ambient conditions, due to such factors as changing building usage, diurnal temperature variation, and wind/rainfall events. These shifts can be sudden, and models of building motions are sensitive to these previously un-documented changes. Further, during stronger motions, such as forced vibration testing, and minor earthquake shaking, natural frequencies are shown to drop by up to 10% (2003 M5.4 Big Bear Earthquake, Δ = 119km), with near-instantaneous recovery once the excitation is over. Moderate earthquakes can temporarily reduce frequencies by up to 30% with no apparent structural damage (1971 M6.6 San Fernando Earthquake, Δ = 31km). Post-event permanent reductions of about 10% have been observed. The ability to monitor these evolving dynamic characteristics makes a re-evaluation of the

  11. Excitation energies with time-dependent density matrix functional theory: Singlet two-electron systems.

    Science.gov (United States)

    Giesbertz, K J H; Pernal, K; Gritsenko, O V; Baerends, E J

    2009-03-21

    Time-dependent density functional theory in its current adiabatic implementations exhibits three striking failures: (a) Totally wrong behavior of the excited state surface along a bond-breaking coordinate, (b) lack of doubly excited configurations, affecting again excited state surfaces, and (c) much too low charge transfer excitation energies. We address these problems with time-dependent density matrix functional theory (TDDMFT). For two-electron systems the exact exchange-correlation functional is known in DMFT, hence exact response equations can be formulated. This affords a study of the performance of TDDMFT in the TDDFT failure cases mentioned (which are all strikingly exhibited by prototype two-electron systems such as dissociating H(2) and HeH(+)). At the same time, adiabatic approximations, which will eventually be necessary, can be tested without being obscured by approximations in the functional. We find the following: (a) In the fully nonadiabatic (omega-dependent, exact) formulation of linear response TDDMFT, it can be shown that linear response (LR)-TDDMFT is able to provide exact excitation energies, in particular, the first order (linear response) formulation does not prohibit the correct representation of doubly excited states; (b) within previously formulated simple adiabatic approximations the bonding-to-antibonding excited state surface as well as charge transfer excitations are described without problems, but not the double excitations; (c) an adiabatic approximation is formulated in which also the double excitations are fully accounted for.

  12. Femtosecond Studies Of Excited Carrier Energy Relaxation And Intervalley Scattering In GaAs and AlGaAs

    Science.gov (United States)

    Lin, W. Z.; LaGasse, M. J.; Schoenlein, R. W.; Zysset, B.; Fujimoto, J. G.

    1988-08-01

    We report the investigation of excited carrier scattering, energy relaxation, and intervalley scattering in GaAs and AlGaAs. Pump and continuum probe absorption saturation measurements provide evidence for femtosecond transient nonthermal carrier distributions and permit a measurement of carrier cooling processes. Measurements performed using a tunable femotsecond laser allow an investigation of intervalley scattering.

  13. Multiple-resonance local wave functions for accurate excited states in quantum Monte Carlo

    NARCIS (Netherlands)

    Zulfikri, Habiburrahman; Amovilli, Claudio; Filippi, Claudia

    2016-01-01

    We introduce a novel class of local multideterminant Jastrow–Slater wave functions for the efficient and accurate treatment of excited states in quantum Monte Carlo. The wave function is expanded as a linear combination of excitations built from multiple sets of localized orbitals that correspond to

  14. Neuroprotection through excitability and mTOR required in ALS motoneurons to delay disease and extend survival.

    Science.gov (United States)

    Saxena, Smita; Roselli, Francesco; Singh, Katyayani; Leptien, Kerstin; Julien, Jean-Pierre; Gros-Louis, Francois; Caroni, Pico

    2013-10-01

    Delaying clinical disease onset would greatly reduce neurodegenerative disease burden, but the mechanisms influencing early preclinical progression are poorly understood. Here, we show that in mouse models of familial motoneuron (MN) disease, SOD1 mutants specifically render vulnerable MNs dependent on endogenous neuroprotection signaling involving excitability and mammalian target of rapamycin (mTOR). The most vulnerable low-excitability FF MNs already exhibited evidence of pathology and endogenous neuroprotection recruitment early postnatally. Enhancing MN excitability promoted MN neuroprotection and reversed misfolded SOD1 (misfSOD1) accumulation and MN pathology, whereas reducing MN excitability augmented misfSOD1 accumulation and accelerated disease. Inhibiting metabotropic cholinergic signaling onto MNs reduced ER stress, but enhanced misfSOD1 accumulation and prevented mTOR activation in alpha-MNs. Modulating excitability and/or alpha-MN mTOR activity had comparable effects on the progression rates of motor dysfunction, denervation, and death. Therefore, excitability and mTOR are key endogenous neuroprotection mechanisms in motoneurons to counteract clinically important disease progression in ALS.

  15. Magnetic excitations and c-f hybridization effect in PrTi2Al20 and PrV2Al20

    Science.gov (United States)

    Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Sakai, Akito; Nakatsuji, Satoru; Harima, Hisatomo

    2013-08-01

    By means of 27Al NMR studies, we have investigated magnetic excitations and the hybridization effect between Pr 4f and conduction electrons in a pair of cubic compounds PrTr2Al20 (Tr=Ti, V). From Knight shift measurements we have evaluated comparative strengths for the c-f hybridization effect in these compounds and confirm a definite increase of hybridization on replacing Ti with V. Analysis of the spin-lattice relaxation rate 1/T1 reveals that the spectral width of magnetic fluctuations in crystalline electric field excited states is strongly temperature dependent. This result indicates that magnetic fluctuations are dominated by strong c-f exchange coupling at high temperatures and thus is nicely consistent with the Kondo picture that features lnT dependence of resistivity over the same temperature region.

  16. Functionally graded piezoelectric materials for modal transducers for exciting bulk and surface acoustic waves.

    Science.gov (United States)

    Yang, Jiashi; Jin, Zhihe; Li, Jiangyu

    2008-07-01

    We show that functionally graded piezoelectric materials can be used to make modal actuators through theoretical analyses of the excitation of extensional motion in an elastic rod and Rayleigh surface waves over an elastic half-plane. The results suggest alternatives with certain advantages for the excitation of bulk and surface acoustic waves.

  17. Localized and collective magnetoplasmon excitations in AlGaN/GaN-based grating-gate terahertz modulators

    Science.gov (United States)

    Nogajewski, K.; Łusakowski, J.; Knap, W.; Popov, V. V.; Teppe, F.; Rumyantsev, S. L.; Shur, M. S.

    2011-11-01

    Magnetotransport and magnetooptics investigations of plasmon excitations in large-area grating-gate terahertz modulators based on AlGaN/GaN high-electron-mobility transistors with different grating-gate duty cycle are reported. We demonstrate that the effect of the gate potential on the ungated region extends beyond the conventional fringing effect distance, ranging over 250-350 nm instead of expected 26-30 nm. This phenomenon enables excitation of the localized gated magnetoplasmon modes only if the inter-finger spacing in the grating gate exceeds 350 nm. For narrower slits, only the collective gated magnetoplasmon modes extending over the entire period of the structure can be excited.

  18. Magnetic structures and excitations in CePd2(Al,Ga)2 series: Development of the "vibron" states

    Science.gov (United States)

    Klicpera, M.; Boehm, M.; Doležal, P.; Mutka, H.; Koza, M. M.; Rols, S.; Adroja, D. T.; Puente Orench, I.; Rodríguez-Carvajal, J.; Javorský, P.

    2017-02-01

    CePd2Al2 -xGax compounds crystallizing in the tetragonal CaBe2Ge2 -type structure (space group P 4 /n m m ) and undergoing a structural phase transition to an orthorhombic structure (C m m e ) at low temperatures were studied by means of neutron scattering. The amplitude-modulated magnetic structure of CePd2Al2 is described by an incommensurate propagation vector k ⃗=(δx,1/2 +δy,0 ) with δx=0.06 and δy=0.04 . The magnetic moments order antiferromagnetically within the a b planes stacked along the c axis and are arranged along the direction close to the orthorhombic a axis with a maximum value of 1.5(1) μB/Ce3 +. CePd2Ga2 reveals a magnetic structure composed of two components: the first is described by the propagation vector k1⃗=(1/2 ,1/2 ,0 ) , and the second one propagates with k2⃗=(0 ,1/2 ,0 ) . The magnetic moments of both components are aligned along the same direction—the orthorhombic [100] direction—and their total amplitude varies depending on the mutual phase of magnetic moment components on each Ce site. The propagation vectors k1⃗ and k2⃗ describe also the magnetic structure of substituted CePd2Al2 -xGax compounds, except the one with x =0.1 .CePd2Al1.9Ga0.1 with magnetic structure described by k ⃗ and k1⃗ stays on the border between pure CePd2Al2 and the rest of the series. Determined magnetic structures are compared with other Ce 112 compounds. Inelastic neutron scattering experiments disclosed three nondispersive magnetic excitations in the paramagnetic state of CePd2Al2 , while only two crystal field (CF) excitations are expected from the splitting of ground state J =5/2 of the Ce3 + ion in a tetragonal/orthorhombic point symmetry. Three magnetic excitations at 1.4, 7.8, and 15.9 meV are observed in the tetragonal phase of CePd2Al2 . A structural phase transition to an orthorhombic structure shifts the first excitation up to 3.7 meV, while the other two excitations remain at almost the same energy. The presence of an additional

  19. The Hawkes process with different excitation functions and its asymptotoc behavior

    DEFF Research Database (Denmark)

    Fierro, Raúl; Leiva, Víctor; Møller, Jesper

    The standard Hawkes process is constructed from a homogeneous Poisson process and using the same exciting function for dierent generations of offspring. We propose an extension of this process by considering different exciting functions. This consideration could be important to be taken into acco......The standard Hawkes process is constructed from a homogeneous Poisson process and using the same exciting function for dierent generations of offspring. We propose an extension of this process by considering different exciting functions. This consideration could be important to be taken...... into account in a number of fields; e.g. in seismology, where main shocks produce aftershocks with possibly different intensities. The main results are devoted to the asymptotic behavior of this extension of the Hawkes process. Indeed, a law of large numbers and a central limit theorem are stated...

  20. Multiple-Resonance Local Wave Functions for Accurate Excited States in Quantum Monte Carlo.

    Science.gov (United States)

    Zulfikri, Habiburrahman; Amovilli, Claudio; Filippi, Claudia

    2016-03-08

    We introduce a novel class of local multideterminant Jastrow-Slater wave functions for the efficient and accurate treatment of excited states in quantum Monte Carlo. The wave function is expanded as a linear combination of excitations built from multiple sets of localized orbitals that correspond to the bonding patterns of the different Lewis resonance structures of the molecule. We capitalize on the concept of orbital domains of local coupled-cluster methods, which is here applied to the active space to select the orbitals to correlate and construct the important transitions. The excitations are further grouped into classes, which are ordered in importance and can be systematically included in the Jastrow-Slater wave function to ensure a balanced description of all states of interest. We assess the performance of the proposed wave function in the calculation of vertical excitation energies and excited-state geometry optimization of retinal models whose π → π* state has a strong intramolecular charge-transfer character. We find that our multiresonance wave functions recover the reference values of the total energies of the ground and excited states with only a small number of excitations and that the same expansion can be flexibly used at very different geometries. Furthermore, significant computational saving can also be gained in the orbital optimization step by selectively mixing occupied and virtual orbitals based on spatial considerations without loss of accuracy on the excitation energy. Our multiresonance wave functions are therefore compact, accurate, and very promising for the calculation of multiple excited states of different character in large molecules.

  1. The decay of excited He from Stochastic Density-Functional Theory: a quantum measurement theory interpretation

    OpenAIRE

    2007-01-01

    Recently, time-dependent current-density functional theory has been extended to include the dynamical interaction of quantum systems with external environments [Phys. Rev. Lett. {\\bf 98}, 226403 (2007)]. Here we show that such a theory allows us to study a fundamentally important class of phenomena previously inaccessible by standard density-functional methods: the decay of excited systems. As an example we study the decay of an ensemble of excited He atoms, and discuss these results in the c...

  2. Investigation of Multiconfigurational Short-Range Density Functional Theory for Electronic Excitations in Organic Molecules

    DEFF Research Database (Denmark)

    Hubert, Mickaël; Hedegård, Erik D.; Jensen, Hans Jørgen Aa

    2016-01-01

    inadequate when the molecule has near-degeneracies and/or low-lying double-excited states. To address these issues we have recently proposed multiconfiguration short-range density-functional theory-MC-srDFT-as a new tool in the toolbox. While initial applications for systems with multireference character......-srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2...

  3. Excited states of hydrogen shallow impurities in GaAs-Ga Al As quantum wells; Estados excitados de impurezas hidrogenoides rasas em pocos quanticos de GaAs-GaAlAs

    Energy Technology Data Exchange (ETDEWEB)

    Neves Carneiro, Gleise das

    1994-12-31

    The study of shallow impurities in semiconductor heterostructures, such as quantum and superlattices, has been of continuous interest over the last years. Successful comparisons between experimental results photoluminescence: N.N Ledentsov et al., Appl. Phys. A 54, 261 (1992) and theoretical calculations [L.E. Oliveira and G.D. Mahan, Phys. Rev. B 47, 2406 (1993)] constitute a strong motivation for an in-depth theoretical study. We present a variational calculation of the binding energies of shallow donors in a Ga-As-AlGaAs quantum well. The energies and variational wave functions associated to the ground state (1s-like) as well as some excited states (2s, 2p{sub xy}, 2p{sub xy}, 3s, 3p{sub xy}, and 3p like) are obtained as functions of the position of the impurity (z{sub i}) in the well. The density of impurity states, intra-donor transition strengths and the infrared absorption spectra are calculated for some of these excited states and results compared with previous theoretical [S. Fraizzoli, F. Bassani, and R. Buczko, Phys. rev. B 41, 5096 (1990)] and experimental works [N.C. Jarosik et al., Phys. Rev. Lett. 54, 1283 (1985)]. (author) 53 refs., 16 figs., 1 tab.

  4. Benchmarks for electronically excited states: Time-dependent density functional theory and density functional theory based multireference configuration interaction

    DEFF Research Database (Denmark)

    Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.;

    2008-01-01

    Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...

  5. The one-electron description of excited states: Natural excitation orbitals of density matrix theory and Kohn-Sham orbitals of density functional theory as ideal orbitals

    Science.gov (United States)

    van Meer, R.; Gritsenko, O. V.; Baerends, E. J.

    2015-10-01

    Linear response density matrix functional theory has been shown to solve the main problems of time-dependent density functional theory (deficient in case of double, charge transfer and bond breaking excitations). However, the natural orbitals preclude the description of excitations as (approximately) simple orbital-to-orbital transitions: many weakly occupied 'virtual' natural orbitals are required to describe the excitations. Kohn-Sham orbitals on the other hand afford for many excitations such a simple orbital description. In this communication we show that a transformation of the set of weakly occupied NOs can be defined such that the resulting natural excitation orbitals (NEOs) restore the single orbital transition structure for excitations generated by the linear response DMFT formalism.

  6. Multiconfiguration Pair-Density Functional Theory Is as Accurate as CASPT2 for Electronic Excitation.

    Science.gov (United States)

    Hoyer, Chad E; Ghosh, Soumen; Truhlar, Donald G; Gagliardi, Laura

    2016-02-04

    A correct description of electronically excited states is critical to the interpretation of visible-ultraviolet spectra, photochemical reactions, and excited-state charge-transfer processes in chemical systems. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory and a new kind of density functional called an on-top density functional. Here, we show that MC-PDFT with a first-generation on-top density functional performs as well as CASPT2 for an organic chemistry database including valence, Rydberg, and charge-transfer excitations. The results are very encouraging for practical applications.

  7. MODAL PARAMETERS EXTRACTION WITH CROSS-CORRELATION FUNCTION AND CROSS-POWER SPECTRUM UNDER UNKNOWN EXCITATION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In most of real operational conditions only response data are measurable while the actual excitations are unknown, so modal parameter must be extracted only from responses. This paper gives a theoretical formulation for the cross-correlation functions and cross-power spectra between the outputs under the assumption of white-noise excitation. It widens the field of modal analysis under ambient excitation because many classical methods by impulse response functions or frequency response functions can be used easily for modal analysis under unknown excitation. The Polyreference Complex Exponential method and Eigensystem Realization Algorithm using cross-correlation functions in time domain and Orthogonal Polynomial method using cross-power spectra in frequency domain are applied to a steel frame to extract modal parameters under operational conditions. The modal properties of the steel frame from these three methods are compared with those from frequency response functions analysis. The results show that the modal analysis method using cross-correlation functions or cross-power spectra presented in this paper can extract modal parameters efficiently under unknown excitation.

  8. Collective state of interwall excitons on GaAs/AlGaAs double quantum wells under pulse resonant excitation

    CERN Document Server

    Larionov, A V; Hvam, J; Soerensen, K

    2002-01-01

    The time evolution and kinetics of the photoluminescence (PL) spectra of the interwall excitons under the pulse resonant excitation of the interwall excitons are studied in the GaAs/AlGaAs binary quantum well. It is established, that the collective exciton phase originates with the time delay relative to the exciting pulse (several nanoseconds), which is conditioned by the density and temperature relaxation to the equilibrium values.The origination of the collective phase of the interwall excitons is accompanied by the strong narrowing of the corresponding photoluminescence line, the superlinear growth of its intensity and large time of change in the degree of the circular polarization.The collective exciton phase originates at the temperatures < 6 K and the interwall excitons densities 3 x 10 sup 1 sup 0 cm sup - sup 2

  9. Test Run to Measure Excitation Function by Using HIRFL-RIBLL System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The discovery of excitation function fluctuation in dissipative heary ion collisions(DHIC)is as important as the discovery of DHIC itself.Many quantitative interpretation of DHIC data only are restricted to the deseription of the energy averaged differential cross sections.However,the description of physical systems should involve both the analysis of averaged values and fluctuations of observables.The phenomenon of excitation

  10. Fabrication and properties of functionally graded NiAl/Al2O3 composites

    Science.gov (United States)

    Miller, D. P.; Lannutti, J. J.; Noebe, R. D.

    1993-01-01

    A modified sedimentation process was used in the production of a functionally gradient material (FGM), NiAl/Al2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3-4 times that of the base NiAl. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving NiAl retardation of a succession of cracks originating in the alumina face.

  11. Application of an excited state LDA exchange energy functional for the calculation of transition energy of atoms within time-independent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Shamim, Md; Harbola, Manoj K, E-mail: sami@iitk.ac.i, E-mail: mkh@iitk.ac.i [Department of Physics, Indian Institute of Technology, Kanpur 208 016 (India)

    2010-11-14

    Transition energies of a new class of excited states (two-gap systems) of various atoms are calculated in time-independent density functional formalism by using a recently proposed local density approximation exchange energy functional for excited states. It is shown that the excitation energies calculated with this functional compare well with those calculated with exact exchange theories.

  12. Proton-proton elastic scattering excitation functions at intermediate energies: Cross sections and analyzing powers

    CERN Document Server

    Hinterberger, F; Altmeier, M; Bauer, F; Bisplinghoff, J; Büsser, K; Busch, M; Colberg, T; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jonas, E; Krause, H; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuk, T; Meinerzhagen, A; Naehle, O; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Trelle, H J; Weise, E; Wellinghausen, A; Woller, K; Ziegler, R

    2000-01-01

    The EDDA experiment at the cooler synchrotron COSY measures proton-proton elastic scattering excitation functions in the momentum range 0.8 - 3.4 GeV/c. In phase 1 of the experiment, spin-averaged differential cross sections were measured continuously during acceleration with an internal polypropylene (CH sub 2) fiber target, taking particular care to monitor luminosity as a function of beam momentum. In phase 2, excitation functions of the analyzing power A sub N and the polarization correlation parameters A sub N sub N , A sub S sub S and A sub S sub L are measured using a polarized proton beam and a polarized atomic hydrogen beam target. The paper presents recent d sigma/d OMEGA and A sub N data. The results provide excitation functions and angular distributions of high precision and internal consistency. No evidence for narrow structures was found. The data are compared to recent phase shift solutions.

  13. Assessing Accuracy of Exchange-Correlation Functionals for the Description of Atomic Excited States

    Science.gov (United States)

    Makowski, Marcin; Hanas, Martyna

    2016-09-01

    The performance of exchange-correlation functionals for the description of atomic excitations is investigated. A benchmark set of excited states is constructed and experimental data is compared to Time-Dependent Density Functional Theory (TDDFT) calculations. The benchmark results show that for the selected group of functionals good accuracy may be achieved and the quality of predictions provided is competitive to computationally more demanding coupled-cluster approaches. Apart from testing the standard TDDFT approaches, also the role of self-interaction error plaguing DFT calculations and the adiabatic approximation to the exchange-correlation kernels is given some insight.

  14. Hardness Measurement of (TiB2-TiAl)/TiAl Symmetrically Function Gradient Materials

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    (TiB2-TiAl)/TiAl symmetrically function gradient materials (FGM) were prepared by spark plasma sintering (SPS). Owing to the difference of the thermal expansion coefficients between TiB2 and TiAl, a compressive surface stress was introduced to the FGM by the thermal expansion mismatch. The hardness values of the uniform materials and the FGM were tested, respectively. For the FGM with a compressive surface stress, hardness is obviously superior to that of the uniform material.When the FGM was subjected to heat treatment,the hardness decreased due to a partial relaxation of the compressive surface stress.

  15. Collective State of Interwell Excitons in GaAs/AlGaAs Double Quantum Wells under Pulse Resonance Excitation

    DEFF Research Database (Denmark)

    Larionov, A. V.; Timofeev, V. B.; Hvam, Jørn Märcher

    2002-01-01

    The time evolution and kinetics of photoluminescence (PL) spectra of interwell excitons in double GaAs/AlGaAs quantum wells (n–i–n structures) have been investigated under the pulse resonance excitation of intrawell 1sHH excitons using a pulsed tunable laser. It is found that the collective exciton......, and a significant increase in the radiative decay rate of the condensed phase. The collective exciton phase arises at temperatures T properties of the collective phase of interwell excitons and experimental manifestations of this coherence...

  16. Excitation quenching in Er3-doped Al2O3 amplifiers

    NARCIS (Netherlands)

    Agazzi, L.; Wörhoff, K.; Pollnau, M.

    2011-01-01

    Spectroscopic investigations in Al2O3:Er waveguides demonstrate that fast quenching of a fraction of ions - undetected in typical lumescence decay measurements - limits the amplifier performance. With optimized parameters 3 dB/cm net gain is feasible.

  17. Communication: Exciton analysis in time-dependent density functional theory: How functionals shape excited-state characters.

    Science.gov (United States)

    Mewes, Stefanie A; Plasser, Felix; Dreuw, Andreas

    2015-11-01

    Excited-state descriptors based on the one-particle transition density matrix referring to the exciton picture have been implemented for time-dependent density functional theory. State characters such as local, extended ππ(∗), Rydberg, or charge transfer can be intuitively classified by simple comparison of these descriptors. Strong effects of the choice of the exchange-correlation kernel on the physical nature of excited states can be found and decomposed in detail leading to a new perspective on functional performance and the design of new functionals.

  18. Excitation energies from range-separated time-dependent density and density matrix functional theory.

    Science.gov (United States)

    Pernal, Katarzyna

    2012-05-14

    Time-dependent density functional theory (TD-DFT) in the adiabatic formulation exhibits known failures when applied to predicting excitation energies. One of them is the lack of the doubly excited configurations. On the other hand, the time-dependent theory based on a one-electron reduced density matrix functional (time-dependent density matrix functional theory, TD-DMFT) has proven accurate in determining single and double excitations of H(2) molecule if the exact functional is employed in the adiabatic approximation. We propose a new approach for computing excited state energies that relies on functionals of electron density and one-electron reduced density matrix, where the latter is applied in the long-range region of electron-electron interactions. A similar approach has been recently successfully employed in predicting ground state potential energy curves of diatomic molecules even in the dissociation limit, where static correlation effects are dominating. In the paper, a time-dependent functional theory based on the range-separation of electronic interaction operator is rigorously formulated. To turn the approach into a practical scheme the adiabatic approximation is proposed for the short- and long-range components of the coupling matrix present in the linear response equations. In the end, the problem of finding excitation energies is turned into an eigenproblem for a symmetric matrix. Assignment of obtained excitations is discussed and it is shown how to identify double excitations from the analysis of approximate transition density matrix elements. The proposed method used with the short-range local density approximation (srLDA) and the long-range Buijse-Baerends density matrix functional (lrBB) is applied to H(2) molecule (at equilibrium geometry and in the dissociation limit) and to Be atom. The method accounts for double excitations in the investigated systems but, unfortunately, the accuracy of some of them is poor. The quality of the other

  19. Measuring fusion excitation functions with RIBs using the stacked target technique: Problems and possible solutions

    Directory of Open Access Journals (Sweden)

    Fisichella M.

    2016-01-01

    Full Text Available For measuring fusion excitation functions, the activation technique with a stack of targets offers the considerable advantage that several reaction energies may be simultaneously measured by using one beam energy. However, its main drawback is the degradation of the beam quality as it passes through the stack due to statistical nature of energy loss processes and any non-uniformity of the stacked targets. If not taken properly into account, this degradation can lead to a wrong determination of the fusion excitation function. In this contribution some results of the investigation of this problem are reported.

  20. The decay of excited He from stochastic density-functional theory: a quantum measurement theory interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Bushong, Neil; Di Ventra, Massimiliano [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0319 (United States)], E-mail: diventra@physics.ucsd.edu

    2008-10-01

    Recently, time-dependent current-density-functional theory has been extended to include the dynamical interaction of quantum systems with external environments (Di Ventra and D'Agosta 2007 Phys. Rev. Lett. 98 226403). Here we show that such a theory allows us to study a fundamentally important class of phenomena previously inaccessible by standard density-functional methods: the decay of excited systems. As an example we study the decay of an ensemble of excited He atoms, and discuss these results in the context of quantum measurement theory.

  1. Excited states properties of organic molecules: from density functional theory to the GW and Bethe-Salpeter Green's function formalisms.

    Science.gov (United States)

    Faber, C; Boulanger, P; Attaccalite, C; Duchemin, I; Blase, X

    2014-03-13

    Many-body Green's function perturbation theories, such as the GW and Bethe-Salpeter formalisms, are starting to be routinely applied to study charged and neutral electronic excitations in molecular organic systems relevant to applications in photovoltaics, photochemistry or biology. In parallel, density functional theory and its time-dependent extensions significantly progressed along the line of range-separated hybrid functionals within the generalized Kohn-Sham formalism designed to provide correct excitation energies. We give an overview and compare these approaches with examples drawn from the study of gas phase organic systems such as fullerenes, porphyrins, bacteriochlorophylls or nucleobases molecules. The perspectives and challenges that many-body perturbation theory is facing, such as the role of self-consistency, the calculation of forces and potential energy surfaces in the excited states, or the development of embedding techniques specific to the GW and Bethe-Salpeter equation formalisms, are outlined.

  2. Photoluminescence of Eu~(2+)-activated Na_(1-x)Al_(1-x)Si_(1+x)O_4 upon UV excitation

    Institute of Scientific and Technical Information of China (English)

    郭宇竹; 余锡宾; 刘洁; 杨绪勇

    2010-01-01

    A convenient high temperature solid-state reaction method was developed to fabricate Na1-xAl1-xSi1+xO4:Eu2+ phosphors.The as-prepared products were characterized by X-ray diffraction(XRD),photoluminescence(PL),and photoluminescence excitation(PLE).The luminescence of Na1-xAl1-xSi1+xO4:Eu2+ phosphors were characterized by the two corresponding emission centers at 535 and 440 nm.The excitation spectrum extended from 250 to 400 nm.A white light was observed by naked eye upon ultraviolet excitation.The relative...

  3. Investigation of Multiconfigurational Short-Range Density Functional Theory for Electronic Excitations in Organic Molecules.

    Science.gov (United States)

    Hubert, Mickaël; Hedegård, Erik D; Jensen, Hans Jørgen Aa

    2016-05-10

    Computational methods that can accurately and effectively predict all types of electronic excitations for any molecular system are missing in the toolbox of the computational chemist. Although various Kohn-Sham density-functional methods (KS-DFT) fulfill this aim in some cases, they become inadequate when the molecule has near-degeneracies and/or low-lying double-excited states. To address these issues we have recently proposed multiconfiguration short-range density-functional theory-MC-srDFT-as a new tool in the toolbox. While initial applications for systems with multireference character and double excitations have been promising, it is nevertheless important that the accuracy of MC-srDFT is at least comparable to the best KS-DFT methods also for organic molecules that are typically of single-reference character. In this paper we therefore systematically investigate the performance of MC-srDFT for a selected benchmark set of electronic excitations of organic molecules, covering the most common types of organic chromophores. This investigation confirms the expectation that the MC-srDFT method is accurate for a broad range of excitations and comparable to accurate wave function methods such as CASPT2, NEVPT2, and the coupled cluster based CC2 and CC3.

  4. Density Relaxation in Time-Dependent Density Functional Theory: Combining Relaxed Density Natural Orbitals and Multireference Perturbation Theories for an Improved Description of Excited States.

    Science.gov (United States)

    Ronca, Enrico; Angeli, Celestino; Belpassi, Leonardo; De Angelis, Filippo; Tarantelli, Francesco; Pastore, Mariachiara

    2014-09-09

    Making use of the recently developed excited state charge displacement analysis [E. Ronca et al., J. Chem. Phys. 140, 054110 (2014)], suited to quantitatively characterize the charge fluxes coming along an electronic excitation, we investigate the role of the density relaxation effects in the overall description of electronically excited states of different nature, namely, valence, ionic, and charge transfer (CT), considering a large set of prototypical small and medium-sized molecular systems. By comparing the response densities provided by time-dependent density functional theory (TDDFT) and the corresponding relaxed densities obtained by applying the Z-vector postlinear-response approach [N. C. Handy and H. F. Schaefer, J. Chem. Phys. 81, 5031 (1984)] with those obtained by highly correlated state-of-the-art wave function calculations, we show that the inclusion of the relaxation effects is imperative to get an accurate description of the considered excited states. We also examine what happens at the quality of the response function when an increasing amount of Hartree-Fock (HF) exchange is included in the functional, showing that the usually improved excitation energies in the case of CT states are not always the consequence of an improved description of their overall properties. Remarkably, we find that the relaxation of the response densities is always able to reproduce, independently of the extent of HF exchange in the functional, the benchmark wave function densities. Finally, we propose a novel and computationally convenient strategy, based on the use of the natural orbitals derived from the relaxed TDDFT density to build zero-order wave function for multireference perturbation theory calculations. For a significant set of different excited states, the proposed approach provided accurate excitation energies, comparable to those obtained by computationally demanding ab initio calculations.

  5. Employment of sawtooth-shaped-function excitation signal and oversampling for improving resistance measurement accuracy

    Science.gov (United States)

    Lin, Ling; Li, Shujuan; Yan, Wenjuan; Li, Gang

    2016-10-01

    In order to achieve higher measurement accuracy of routine resistance without increasing the complexity and cost of the system circuit of existing methods, this paper presents a novel method that exploits a shaped-function excitation signal and oversampling technology. The excitation signal source for resistance measurement is modulated by the sawtooth-shaped-function signal, and oversampling technology is employed to increase the resolution and the accuracy of the measurement system. Compared with the traditional method of using constant amplitude excitation signal, this method can effectively enhance the measuring accuracy by almost one order of magnitude and reduce the root mean square error by 3.75 times under the same measurement conditions. The results of experiments show that the novel method can attain the aim of significantly improve the measurement accuracy of resistance on the premise of not increasing the system cost and complexity of the circuit, which is significantly valuable for applying in electronic instruments.

  6. Relativistic time-dependent density functional calculations for the excited states of the cadmium dimer

    Energy Technology Data Exchange (ETDEWEB)

    Kullie, Ossama, E-mail: kullie@uni-kassel.de [Institute de Chimie de Strasbourg, CNRS et Université de Strasbourg, Laboratoire de Chimie Quantique, 4 rue Blaise Pascal, 67070 Strasbourg (France); Theoretical Physics, Institute for Physics, Department of Mathematics and Natural Science, University of Kassel (Germany)

    2013-03-29

    Highlights: ► The achievement of CAMB3LYP functional for excited states in framework of TD-DFT. ► Relativistic 4-components calculations for the excited states of the Cd{sub 2} dimer. ► Relativistic Spin-Free calculations for the excited states of Cd{sub 2} dimer. ► A comparison of the achievements of different types of DFT approximations upon Cd{sub 2}. - Abstract: In this paper we present a time-dependent density functional study for the ground-state as well the 20-lowest laying excited states of the cadmium dimer Cd{sub 2}, we analyze its spectrum obtained from all electrons calculations performed with time-depended density functional for the relativistic Dirac-Coulomb- and relativistic spin-free-Hamiltonian as implemented in DIRAC-PACKAGE. The calculations were obtained with different density functional approximations, and a comparison with the literature is given as far as available. Our result is very encouraging, especially for the lowest excited states of this dimer, and is expected to be enlightened for similar systems. The result shows that only long-range corrected functionals such as CAMB3LYP, gives the correct asymptotic behavior for the higher states. A comparable but less satisfactory results were obtained with B3LYP and PBE0 functionals. Spin-free-Hamiltonian is shown to be very efficient for systems containing heavy elements such as Cd{sub 2} in frameworks of (time-dependent) density functional without introducing large errors.

  7. Modelling excited states of weakly bound complexes with density functional theory.

    Science.gov (United States)

    Briggs, Edward A; Besley, Nicholas A

    2014-07-28

    The binding within the ethene-argon and formaldehyde-methane complexes in the ground and electronically excited states is studied with equation of motion coupled cluster theory (EOM-CCSD), second-order Møller-Plesset perturbation theory (MP2) and density functional theory with dispersion corrections (DFT-D). Electronically excited states are studied within MP2 and Kohn-Sham DFT formalisms by exploiting a procedure called the maximum overlap method that allows convergence of the relevant self-consistent field equations to higher energy (or excited state) solutions. Potential energy curves computed using MP2 are in good agreement with the EOM-CCSD calculations for both the valence and Rydberg excited states studied. For the DFT-D approach, B3LYP-D3/aug-cc-pVTZ calculations are found to be in agreement with EOM-CCSD for the ground and valence excited states. However, for the π3s Rydberg state of ethene-argon and the n3s Rydberg state of formaldehyde-methane significant deviation is observed, and this disagreement with EOM-CCSD is present for a variety of DFT-D based approaches. Variation of the parameters within the D2 dispersion correction results in closer agreement with EOM-CCSD for the Rydberg states but demonstrates that a different parameterisation from the ground state is required for these states. This indicates that time-dependent density functional theory calculations based upon a DFT-D reference may be satisfactory for excitations to valence states, but will potentially be inaccurate for excitations to Rydberg states, or more generally states where the nature of the electron density is significantly different from the ground state.

  8. Plasma Heating in Highly Excited GaN/AlGaN Multiple Quantum Wells

    Energy Technology Data Exchange (ETDEWEB)

    Botchkarev, A; Chow, W W; Jiang, H X; Lin, J Y; Mair, R; Morkoc, H; Zeng, K C

    1998-10-09

    Plasma Heating in Highly Excited GaN/AIGaN Multiple Quantum @@lvEu Wells w f + 1998 %p, K. C. Zeng, R. Mair, J. Y. Liz and H. X. Jiang a) ` fabrication and understanding of MQW lasers [2-5]. For the design of these lasers, one on RT optical studies. Our results revealed that in the GaN/AIGaN MQWS, plasma heating strongly effects the carrier distribution between the confined and unconfined band-to-band and fke excitonic transitions [7]. In the MQW sample under low the unconfined states as determined from the band structure. sample under high Lxc, we varied the excitation intensity by one order of magnitude from 0.110 to IO. The carrier density is estimated to be about N=1012/cm2 (at UC= 0.1 Io) to 1013/cm2 (at 1=== l.). We plotted the PL spectra for four representative excitation fimction of injected carrier density N (open squares). The ratio starts at a value of about 18% for N=1012/cm2 (& = O. lb), and reaches a value over 64 `XO for N=1013/cm2 (& = regions is a loss to optical gain. The carrier density is ve~ high in our experiment and an electron-hole plasma (EHP) state is expected. Because the carrier transfer process plasma temperature. The laser pump energy is about 4.3 eV, which is far above the energy band gap of the sample studied here. This may result in a hot carrier population carrier densities and plasma temperatures. Using a phenomenological expression based The calculated ratio of carriers in the unconfked to the confined states (Ima~ kf) as a finction of carrier density at different temperatures are plotted in Fig. 3 (solid lines). The figure shows that the experiment results can only be explained by plasma heating of the injected carriers at high & ( TP > TJ. The transparency carrier densities for GaN/AIXGal.XN MQW structures with well thickness from 2 to 4 nm were calculated to be around 1x 1012/cm2 [10]. It is thus obvious from Fig. 3 that under high carrier injection density above the transparency density, the plasma temperature, TP, is no

  9. Surface Energy and Work Function Control of AlOx/Al Surfaces by Fluorinated Benzylphosphonic Acids.

    Science.gov (United States)

    Abraham, Ffion; Ford, William E; Scholz, Frank; Nelles, Gabriele; Sandford, Graham; von Wrochem, Florian

    2016-05-11

    The performance of organic electronic devices can be significantly improved by modifying metal electrodes with organic monolayers, which alter the physical and chemical nature of the interface between conductor and semiconductor. In this paper we examine a series of 12 phosphonic acid compounds deposited on the native oxide layer of aluminum (AlOx/Al), an electrode material with widespread applications in organic electronics. This series includes dodecylphosphonic acid as a reference and 11 benzylphosphonic acids, seven of which are fluorinated, including five newly synthesized derivatives. The monolayers are experimentally characterized by contact angle goniometry and by X-ray photoemission spectroscopy (XPS), and work function data obtained by low-intensity XPS are correlated with molecular dipoles obtained from DFT calculations. We find that monolayers are formed with molecular areas ranging from 17.7 to 42.9 Å(2)/molecule, and, by the choice of appropriate terminal groups, the surface energy can be tuned from 23.5 mJ/m(2) to 70.5 mJ/m(2). Depending on the number and position of fluorine substituents on the aromatic rings, a variation in the work function of AlOx/Al substrates over a range of 0.91 eV is achieved, and a renormalization procedure based on molecular density yields a surprising agreement of work function changes with interface dipoles as expected from Helmholtz' equation. The ability to adjust energetics and adhesion at organic semiconductor/AlOx interfaces has immediate applications in devices such as OLEDs, OTFTs, organic solar cells, and printed organic circuits.

  10. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism

    CERN Document Server

    Nagesh, Jayashree; Brumer, Paul; Izmaylov, Artur F

    2016-01-01

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A.F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory (TD-DFT) framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Stratman-Scuseria-Frisch atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1-naphthyl)-methyl)-anthracene and 4-((2-naphthyl)-methyl)-benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that are not accessible using simple density difference analysis.

  11. Exact ensemble density functional theory for excited states in a model system: Investigating the weight dependence of the correlation energy

    Science.gov (United States)

    Deur, Killian; Mazouin, Laurent; Fromager, Emmanuel

    2017-01-01

    Ensemble density functional theory (eDFT) is an exact time-independent alternative to time-dependent DFT (TD-DFT) for the calculation of excitation energies. Despite its formal simplicity and advantages in contrast to TD-DFT (multiple excitations, for example, can be easily taken into account in an ensemble), eDFT is not standard, which is essentially due to the lack of reliable approximate exchange-correlation (x c ) functionals for ensembles. Following Smith et al. [Phys. Rev. B 93, 245131 (2016), 10.1103/PhysRevB.93.245131], we propose in this work to construct an exact eDFT for the nontrivial asymmetric Hubbard dimer, thus providing more insight into the weight dependence of the ensemble x c energy in various correlation regimes. For that purpose, an exact analytical expression for the weight-dependent ensemble exchange energy has been derived. The complementary exact ensemble correlation energy has been computed by means of Legendre-Fenchel transforms. Interesting features like discontinuities in the ensemble x c potential in the strongly correlated limit have been rationalized by means of a generalized adiabatic connection formalism. Finally, functional-driven errors induced by ground-state density-functional approximations have been studied. In the strictly symmetric case or in the weakly correlated regime, combining ensemble exact exchange with ground-state correlation functionals gives better ensemble energies than when calculated with the ground-state exchange-correlation functional. However, when approaching the asymmetric equiensemble in the strongly correlated regime, the former approximation leads to highly curved ensemble energies with negative slope which is unphysical. Using both ground-state exchange and correlation functionals gives much better results in that case. In fact, exact ensemble energies are almost recovered in some density domains. The analysis of density-driven errors is left for future work.

  12. Magnetic field control and wavelength tunability of SPP excitations using Al2O3/SiO2/Fe structures

    Science.gov (United States)

    Kaihara, Terunori; Shimizu, Hiromasa; Cebollada, Alfonso; Armelles, Gaspar

    2016-09-01

    Here, we show the high wavelength tunability and magnetic field modulation of surface plasmon polaritons (SPPs) of a waveguide mode that Double-layer Dielectrics and Ferromagnetic Metal, Al2O3/SiO2/Fe, trilayer structures exhibit when excited in the Otto configuration of attenuated total reflection setup. First by modeling, and then experimentally, we demonstrate that it is possible to tune the wavelength at which the angular dependent reflectance of these structures reaches its absolute minimum by simply adjusting the SiO2 intermediate dielectric layer thickness. This precise wavelength corresponds to the cut-off condition of SPPs' waveguide mode supported by the proposed structure, and it can be then switched between two values upon magnetization reversal of the Fe layer. In this specific situation, a large enhancement of the transverse magneto-optical effect is also obtained.

  13. Fabrication of Al-Al3Ti/Ti3Al Functionally Graded Materials under a Centrifugal Force

    Directory of Open Access Journals (Sweden)

    Yoshimi Watanabe

    2010-09-01

    Full Text Available Fabrication of Al-Al3Ti functionally graded materials (FGMs under the centrifugal force has recently attracted some attention. The controlled compositional gradient of the fabricated FGMs, the low cost of the process, and the good mold filling, are the main advantages of the centrifugal method (CM. Using the conventional CM techniques such as the centrifugal solid-particle method and centrifugal in-situ method, FGMs rings with gradually distributed properties could be achieved. As a more practical choice, the centrifugal mixed-powder method (CMPM was recently proposed to obtain FGMs containing nano-particles selectively dispersed in the outer surface of the fabricated parts. However, if a control of the particles morphology, compound formulas or sizes, is desired, another CM technique is favored. As a development of CMPM, our novel reaction centrifugal mixed-powder method (RCMPM has been presented. Using RCMPM, Al‑Al3Ti/Ti3Al FGMs with good surface properties and temperature controlled compositional gradient could be achieved. In this short review, this novel method will be discussed in detail and the effect of RCMPM processing temperature on the reinforcement particles morphology, size and distribution through the fabricated samples, will be reviewed.

  14. Luminescence Properties of(Y,Gd)Al3(BO3)4∶Eu3+ under VUV excitation

    Institute of Scientific and Technical Information of China (English)

    刘端阳; 何大伟; 康凯; 李春棠; 李少霞

    2004-01-01

    (Y, Gd)Al3(BO3)4∶Eu3+ samples were prepared by the conventional solid state reaction. The XRD results indicate that the crystal symmetry is low. The excitation spectrum is composed of two broad bands centered at about 170 and 250 nm respectively. In the emission spectra, the peak wavelength is about 616 nm under 147 nm VUV excitation. The luminescent chromaticity coordinate and the relative intensity change along with Gd3+ mole concentration in the range of 0.15 to 0.85 mol(and Eu3+ mole concentration, 0.02 to 0.1 mol). The correlative data show that the concentration quenching occurs when the Eu3+ mole concentration ranges from 0.02 to 0.1 mol, and the Gd3+→Gd3+, Gd3+→Eu3+ and host→Eu3+, Gd3+ energy transfers exist, and Gd3+ mole concentration influences Eu3+ emission.

  15. Plasmon excitations in sodium atomic planes: a time-dependent density functional theory study.

    Science.gov (United States)

    Wang, Bao-Ji; Xu, Yuehua; Ke, San-Huang

    2012-08-07

    The collective electronic excitation in planar sodium clusters is studied by time-dependent density functional theory calculations. The formation and development of the resonances in photoabsorption spectra are investigated in terms of the shape and size of the two-dimensional (2D) systems. The nature of these resonances is revealed by the frequency-resolved induced charge densities present on a real-space grid. For long double chains, the excitation is similar to that in long single atomic chains, showing longitudinal modes, end and central transverse modes. However, for 2D planes consisting of (n × n) atoms with n being up to 16, new 2D characteristic modes emerge regardless of the symmetries considered. For in-plane excitations, besides the equivalent end mode, mixed modes with contrary polarity occur. The relation between the frequency of the primary modes and the system size is similar to the case of a 2D electron gas but with a correction due to the realistic atomic structure. For excitations perpendicular to the plane there are corner, side center, bulk center, and circuit modes. Our calculation reveals the importance of dimensionality for plasmon excitation and how it evolves from 1D to 2D.

  16. Measurement of fusion excitation functions in the system {sup 78}Kr + {sup 100}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others

    1995-08-01

    Earlier measurements of fusion reactions involving {sup 78}Kr and {sup 100}Mo projectiles and Ni-targets showed surprisingly large fusion yields at low energies which could not be explained by coupled-channels calculations. The main difference to similar measurements involving the neighboring {sup 86}Kr and {sup 92}Mo isotopes was the different slope of the excitation functions at sub-barrier energies. An analysis of a variety of experiments showed a correlation between the nuclear structure and the slope of the excitation functions, with the {open_quotes}soft{close_quotes} transitional nuclei ({sup 78}Kr, {sup 100}Mo) exhibiting shallower slopes than the {open_quotes}stiff{close_quotes} nuclei ({sup 86}Kr, {sup 92}Mo) measured at the same energies with respect to the barrier. In this experiment we studied the fusion excitation function involving two transitional nuclei {sup 78}Kr + {sup 100}Mo. The measurements were performed with {sup 78}Kr beams from the ECR source at energies between 285-370 MeV. Separation of the evaporation nucleus from the elastically scattered particles was achieved by measuring time-of-flight and magnetic rigidity in the gas-filled spectrograph. The data were completely analyzed. A comparison of the cross sections with measurements for the system {sup 86}Kr + {sup 92}Mo populating the same compound nucleus {sup 178}Pt. It shows good agreement at the highest energies, but quite different falloffs of the excitation functions toward lower energies. Coupled-channels calculations, including multi-phonon excitation for the two systems, are being performed.

  17. Functionally Graded Al Alloy Matrix In-Situ Composites

    Science.gov (United States)

    Kumar, S.; Subramaniya Sarma, V.; Murty, B. S.

    2010-01-01

    In the present work, functionally graded (FG) aluminum alloy matrix in-situ composites (FG-AMCs) with TiB2 and TiC reinforcements were synthesized using the horizontal centrifugal casting process. A commercial Al-Si alloy (A356) and an Al-Cu alloy were used as matrices in the present study. The material parameters (such as matrix and reinforcement type) and process parameters (such as mold temperature, mold speed, and melt stirring) were found to influence the gradient in the FG-AMCs. Detailed microstructural analysis of the composites in different processing conditions revealed that the gradients in the reinforcement modify the microstructure and hardness of the Al alloy. The segregated in-situ formed TiB2 and TiC particles change the morphology of Si particles during the solidification of Al-Si alloy. A maximum of 20 vol pct of reinforcement at the surface was achieved by this process in the Al-4Cu-TiB2 system. The stirring of the melt before pouring causes the reinforcement particles to segregate at the periphery of the casting, while in the absence of such stirring, the particles are segregated at the interior of the casting.

  18. Multiple hydrogen bonding in excited states of aminopyrazine in methanol solution: time-dependent density functional theory study.

    Science.gov (United States)

    Chai, Shuo; Yu, Jie; Han, Yong-Chang; Cong, Shu-Lin

    2013-11-01

    Aminopyrazine (AP) and AP-methanol complexes have been theoretically studied by using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The excited-state hydrogen bonds are discussed in detail. In the ground state the intermolecular multiple hydrogen bonds can be formed between AP molecule and protic solvents. The AP monomer and hydrogen-bonded complex of AP with one methanol are photoexcited initially to the S2 state, and then transferred to the S1 state via internal conversion. However the complex of AP with two methanol molecules is directly excited to the S1 state. From the calculated electronic excited energies and simulated absorption spectra, we find that the intermolecular hydrogen bonds are strengthened in the electronic excited states. The strengthening is confirmed by the optimized excited-state geometries. The photochemical processes in the electronic excited states are significantly influenced by the excited-state hydrogen bond strengthening.

  19. Measurement and evaluation of the excitation functions for alpha particle induced nuclear reactions on niobium

    CERN Document Server

    Tarkanyi, F; Szelecsenyi, F; Sonck, M; Hermanne, A

    2002-01-01

    Alpha particle induced nuclear reactions were investigated with the stacked foil activation technique on natural niobium targets up to 43 MeV. Excitation functions were measured for the production of sup 9 sup 6 sup m sup g Tc, sup 9 sup 5 sup m Tc, sup 9 sup 5 sup g Tc, sup 9 sup 4 sup g Tc, sup 9 sup 5 sup m sup g Nb and sup 9 sup 2 sup m Nb. Cumulative cross-sections, thick target yields and activation functions were deduced and compared with available literature data. Applications of the excitation functions in the field of thin layer activation techniques and beam monitoring are also discussed.

  20. Importance of local exact exchange potential in hybrid functionals for accurate excited states

    CERN Document Server

    Kim, Jaewook; Hwang, Sang-Yeon; Ryu, Seongok; Choi, Sunghwan; Kim, Woo Youn

    2016-01-01

    Density functional theory has been an essential analysis tool for both theoretical and experimental chemists since accurate hybrid functionals were developed. Here we propose a local hybrid method derived from the optimized effective potential (OEP) method and compare its distinct features with conventional nonlocal ones from the Hartree-Fock (HF) exchange operator. Both are formally exact for ground states and thus show similar accuracy for atomization energies and reaction barrier heights. For excited states, the local version yields virtual orbitals with N-electron character, while those of the nonlocal version have mixed characters between N- and (N+1)-electron orbitals. As a result, the orbital energy gaps from the former well approximate excitation energies with a small mean absolute error (MAE = 0.40 eV) for the Caricato benchmark set. The correction from time-dependent density functional theory with a simple local density approximation kernel further improves its accuracy by incorporating multi-config...

  1. Energy levels, radiative rates and electron impact excitation rates for transitions in Al X

    CERN Document Server

    Aggarwal, K M

    2013-01-01

    Energy levels, radiative rates and lifetimes are calculated among the lowest 98 levels of the n <= 4 configurations of Be-like Al X. The GRASP (General-purpose Relativistic Atomic Structure Package) is adopted and data are provided for all E1, E2, M1 and M2 transitions. Similar data are also obtained with the Flexible Atomic Code (FAC) to assess the accuracy of the calculations. Based on comparisons between calculations with the two codes as well as with available measurements, our listed energy levels are assessed to be accurate to better than 0.3%. However, the accuracy for radiative rates and lifetimes is estimated to be about 20%. Collision strengths are also calculated for which the Dirac Atomic R-matrix Code (DARC) is used. A wide energy range (up to 380 Ryd) is considered and resonances resolved in a fine energy mesh in the thresholds region. The collision strengths are subsequently averaged over a Maxwellian velocity distribution to determine effective collision strengths up to a temperature of 1.6...

  2. Optical excitation processes in the near band-edge region of KAlSi3O8 and NaAlSi3O8 feldspar

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Mauz, B.; Lang, A.;

    2006-01-01

    A complex variety of excitation and relaxation pathways are available for charge in naturally occurring NaAlSi3O8 and KAlpSi(3)O(8) feldspar crystals, when excited with photons in the trans-band-edge energy range 4-12 eV These can involve a mixture of electronic transitions associated with defect...... states, the conduction and valence bands and their associated band-tails. In order to demonstrate that a relationship exists between these processes, combinations of three spectroscopic techniques are deployed in this work: luminescence excitation/emission mapping, energy-resolved photo...... emission in the materials. Luminescence and phosphorescence excitation spectra provide additional, complementary, information regarding the excited states of the blue-emitting defects, including their transition lifetimes and decay paths. Red emission associated with Fe3+ luminescence is mostly isolated...

  3. Excited-state charge coupled proton transfer reaction in dipole-functionalized salicylideneaniline

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Kew-Yu, E-mail: kyuchen@fcu.edu.tw; Hu, Jiun-Wei

    2015-03-15

    Based on design and synthesis of salicylideneaniline derivatives 1–4, we demonstrate an exceedingly useful system to investigate the excited-state intramolecular charge transfer (ESICT) coupled with excited-state intramolecular proton transfer (ESIPT) reaction via the dipolar functionality of Schiff base salicylideneaniline. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess a strong intramolecular six-membered-ring hydrogen bond. Compounds 2–4 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 1 exhibits remarkable dual emission due to the different solvent-polarity environments between ESICT and ESIPT states. Moreover, the geometric structures, frontier molecular orbitals (MOs) and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations. - Highlights: • A dipole-functionalized salicylideneaniline derivative was synthesized. • The Schiff base exhibits remarkable dual emission. • A novel ESICT/ESIPT coupled system was created.

  4. Application of Excitation Function to the Prediction of RI Level Caused by Corona Discharge

    Institute of Scientific and Technical Information of China (English)

    ZHU Lingyu; JI Shengchang; HUI Sisi; GUO Jun; LI Yansong; FU Chenzhao

    2012-01-01

    Radio interference (RI), as an aftereffect of corona discharge, is an important research topic in the field of electromagnetic compatibility, where excitation function is applied broadly to the prediction of RI level. This paper presents the theory of excitation function method used in the RI level prediction. Then, some practical problems related to this method are discussed. The propagation procedure of corona current is solved by the phase-modal transformation, and the impedance matrix of multi transmission lines is calculated by a double logarithmic approximate model of Carson's Ground-Return impedance. At the same time, in order to calculate the RI level when total line corona is assumed, an analytical formula is deduced for integral operation. Based on the above solutions, an algorithm is presented and applied to the prediction of RI level of a practical overhead transmission line. Comparison of prediction and measurement results indicates that the algorithm proposed in this paper is effective and feasible.

  5. Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

    Energy Technology Data Exchange (ETDEWEB)

    Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Gregorich, K.E.; Hoffman, D.C.; Nitsche, H.

    2010-03-19

    The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.

  6. Communication: Excited states, dynamic correlation functions and spectral properties from full configuration interaction quantum Monte Carlo.

    Science.gov (United States)

    Booth, George H; Chan, Garnet Kin-Lic

    2012-11-21

    In this communication, we propose a method for obtaining isolated excited states within the full configuration interaction quantum Monte Carlo framework. This method allows for stable sampling with respect to collapse to lower energy states and requires no uncontrolled approximations. In contrast with most previous methods to extract excited state information from quantum Monte Carlo methods, this results from a modification to the underlying propagator, and does not require explicit orthogonalization, analytic continuation, transient estimators, or restriction of the Hilbert space via a trial wavefunction. Furthermore, we show that the propagator can directly yield frequency-domain correlation functions and spectral functions such as the density of states which are difficult to obtain within a traditional quantum Monte Carlo framework. We demonstrate this approach with pilot applications to the neon atom and beryllium dimer.

  7. The transfer function method for gear system dynamics applied to conventional and minimum excitation gearing designs

    Science.gov (United States)

    Mark, W. D.

    1982-01-01

    A transfer function method for predicting the dynamic responses of gear systems with more than one gear mesh is developed and applied to the NASA Lewis four-square gear fatigue test apparatus. Methods for computing bearing-support force spectra and temporal histories of the total force transmitted by a gear mesh, the force transmitted by a single pair of teeth, and the maximum root stress in a single tooth are developed. Dynamic effects arising from other gear meshes in the system are included. A profile modification design method to minimize the vibration excitation arising from a pair of meshing gears is reviewed and extended. Families of tooth loading functions required for such designs are developed and examined for potential excitation of individual tooth vibrations. The profile modification design method is applied to a pair of test gears.

  8. Two-photon excitation of porphyrin-functionalized porous silicon nanoparticles for photodynamic therapy.

    Science.gov (United States)

    Secret, Emilie; Maynadier, Marie; Gallud, Audrey; Chaix, Arnaud; Bouffard, Elise; Gary-Bobo, Magali; Marcotte, Nathalie; Mongin, Olivier; El Cheikh, Khaled; Hugues, Vincent; Auffan, Mélanie; Frochot, Céline; Morère, Alain; Maillard, Philippe; Blanchard-Desce, Mireille; Sailor, Michael J; Garcia, Marcel; Durand, Jean-Olivier; Cunin, Frédérique

    2014-12-01

    Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect.

  9. Integral measurement of break-up excitation function using a multiple silicon telescope

    Energy Technology Data Exchange (ETDEWEB)

    Corre, J.M.; Anne, R.; Lewitowicz, M.; Saint-Laurent, M.G. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Borcea, C.; Carstoiu, F.; Negoita, F. [Institute of Atomic Physics, Bucharest (Romania); Borrel, V.; Guillemaud-Mueller, D.; Mueller, A.C.; Pougheon, F.; Sorlin, O. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Dlouhy, Z. [NPI, Rez (Czech Republic); Fomichev, A.S.; Lukyanov, S.M.; Penoinzhkevich, Y.E.; Skobelev, N.K. [Joint Inst. for Nuclear Research, Dubna (Russian Federation); Kordyasz, A. [Warsaw Univ. (Poland). Inst. Fizyki Doswiadczalnej

    1994-12-31

    A simple method is proposed for measuring the inclusive break-up excitation function which the experimental device, consisting of a set of successive silicon detectors, serves the double purpose of decreasing the incident beam energy and of detecting and identifying the reaction products. Monte Carlo simulations revealed the merits and the limitations of the method. Finally, experimental data for tritons are treated in order to obtain relevant physical informations (authors). 9 refs., 9 figs.

  10. Excitation Gaps of Finite-Sized Systems from Optimally Tuned Range-Separated Hybrid Functionals.

    Science.gov (United States)

    Kronik, Leeor; Stein, Tamar; Refaely-Abramson, Sivan; Baer, Roi

    2012-05-08

    Excitation gaps are of considerable significance in electronic structure theory. Two different gaps are of particular interest. The fundamental gap is defined by charged excitations, as the difference between the first ionization potential and the first electron affinity. The optical gap is defined by a neutral excitation, as the difference between the energies of the lowest dipole-allowed excited state and the ground state. Within many-body perturbation theory, the fundamental gap is the difference between the corresponding lowest quasi-hole and quasi-electron excitation energies, and the optical gap is addressed by including the interaction between a quasi-electron and a quasi-hole. A long-standing challenge has been the attainment of a similar description within density functional theory (DFT), with much debate on whether this is an achievable goal even in principle. Recently, we have constructed and applied a new approach to this problem. Anchored in the rigorous theoretical framework of the generalized Kohn-Sham equation, our method is based on a range-split hybrid functional that uses exact long-range exchange. Its main novel feature is that the range-splitting parameter is not a universal constant but rather is determined from first principles, per system, based on satisfaction of the ionization potential theorem. For finite-sized objects, this DFT approach mimics successfully, to the best of our knowledge for the first time, the quasi-particle picture of many-body theory. Specifically, it allows for the extraction of both the fundamental and the optical gap from one underlying functional, based on the HOMO-LUMO gap of a ground-state DFT calculation and the lowest excitation energy of a linear-response time-dependent DFT calculation, respectively. In particular, it produces the correct optical gap for the difficult case of charge-transfer and charge-transfer-like scenarios, where conventional functionals are known to fail. In this perspective, we overview

  11. Rotational excitation of AlCl induced by its collision with helium: cross sections and collisional rate coefficients

    Science.gov (United States)

    Pamboundom, Mama; Tchakoua, Théophile; Nsangou, Mama

    2016-04-01

    In this work, inelastic rotational collision of AlCl with helium was studied. The CCSD(T) method was used for the computation of an accurate two dimensional potential energy surface (PES). In the calculation of the PES, Al-Cl bond was frozen at the experimental value 4.02678 a0. The aug-cc-pVQZ basis sets of Dunning was used throughout the computational process. This basis was completed with a set of 3s3p2d2f1g bond functions placed at mid-distance between the center of mass of AlCl and He atom for a better description of the van der Waals interaction energy. The PES of AlCl-He was found to have a global minimum at (R=8.65 a0, θ=0 degree), a local minimum at (R=7.45 a0, θ=82 degree) and a saddle point at (R=7.9 a0, θ=56 degree). The depths of the minima were 20.2 cm^{-1} and 19.8 cm^{-1} respectively for θ=0 and 84 degrees. The height of the saddle point with respect to the global minimum was 1.3 cm^{-1}. The PES, the result of an analytical fit, was expanded in terms of Legendre polynomials, then used for the evaluation of state-to-state rotational integral cross sections for the collision of AlCl with He in the close coupling approach. The collisional cross sections for the transitions occurring among the 17 first rotational levels of AlCl were calculated for kinetic energies up to 4000 cm^{-1}. Collisional rate coefficients between these rotational levels were computed for low and moderate kinetic temperatures ranging from 30 to 500 K. A propensity rule that favors odd Δ j transitions was found.

  12. Excited State Contributions to the Heavy Baryon Fragmentation Functions in a Quark-Diquark Model

    CERN Document Server

    Adamov, A D; Goldstein, Gary R.

    2001-01-01

    Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. The resulting $\\Lambda_b$ production rate and polarization at LEP energies are in agreement with experiment. The $\\Lambda_c$ and $\\Xi_c$ functions are also obtained. The spin independent $f_1(z)$ is compared to data. The integrated values for production rates agree with the data.

  13. Constraining nuclear photon strength functions by the decay properties of photo-excited states

    Energy Technology Data Exchange (ETDEWEB)

    Isaak, J., E-mail: j.isaak@gsi.de [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt (Germany); Savran, D. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt (Germany); Krtička, M. [Faculty of Mathematics and Physics, Charles University, Prague 8 (Czech Republic); Ahmed, M.W. [Department of Mathematics and Physics, North Carolina Central University, Durham, NC 27707 (United States); Department of Physics, Duke University, Durham, NC 27708 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Beller, J. [Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt (Germany); Fiori, E. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt (Germany); Glorius, J. [Institut für Angewandte Physik, Goethe-Universität Frankfurt, 60438 Frankfurt (Germany); Kelley, J.H. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Löher, B. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt (Germany); and others

    2013-12-18

    A new approach for constraining the low-energy part of the electric dipole Photon Strength Function (E1-PSF) is presented. Experiments at the Darmstadt High-Intensity Photon Setup and the High Intensity γ{sup →}-Ray Source have been performed to investigate the decay properties of {sup 130}Te between 5.50 and 8.15 MeV excitation energy. In particular, the average γ-ray branching ratio to the ground state and the population intensity of low-lying excited states have been studied. A comparison to the statistical model shows that the latter is sensitive to the low-energy behavior of the E1-PSF, while the average ground state branching ratio cannot be described by the statistical model in the energy range between 5.5 and 6.5 MeV.

  14. Charge-Transfer Excited States in Aqueous DNA: Insights from Many-Body Green's Function Theory

    Science.gov (United States)

    Yin, Huabing; Ma, Yuchen; Mu, Jinglin; Liu, Chengbu; Rohlfing, Michael

    2014-06-01

    Charge-transfer (CT) excited states play an important role in the excited-state dynamics of DNA in aqueous solution. However, there is still much controversy on their energies. By ab initio many-body Green's function theory, together with classical molecular dynamics simulations, we confirm the existence of CT states at the lower energy side of the optical absorption maximum in aqueous DNA as observed in experiments. We find that the hydration shell can exert strong effects (˜1 eV) on both the electronic structure and CT states of DNA molecules through dipole electric fields. In this case, the solvent cannot be simply regarded as a macroscopic screening medium as usual. The influence of base stacking and base pairing on the CT states is also discussed.

  15. Fusion excitation function measurement for 6Li+64Ni at near-barrier energies

    Directory of Open Access Journals (Sweden)

    Shaikh Md. Moin

    2015-01-01

    Full Text Available Total fusion excitation function has been measured for the reaction of weakly bound 6Li projectile on medium mass 64Ni target at energies near the Coulomb barrier of the system. Online characteristic γ-ray detection method has been used to identify and determine the cross sections of the residues. No suppression of total fusion cross section (σTF is observed at above barrier energies. But enhancement of measured cross section with respect to the one-dimensional barrier penetration model (1-DBPM calculation is observed at below barrier energies. The enhancement can not be explained by coupled channels calculation with dominant projectile and target excitations as well as one-neutron stripping reaction.

  16. Excitation energy-transfer in functionalized nanoparticles: Going beyond the Förster approach

    Science.gov (United States)

    Gil, G.; Corni, S.; Delgado, A.; Bertoni, A.; Goldoni, G.

    2016-02-01

    We develop a novel approach to treat excitation energy transfer in hybrid nanosystems composed by an organic molecule attached to a semiconductor nanoparticle. Our approach extends the customary Förster theory by considering interaction between transition multipole moments of the nanoparticle at all orders and a point-like transition dipole moment representing the molecule. Optical excitations of the nanoparticle are described through an envelope-function configuration interaction method for a single electron-hole pair. We applied the method to the prototypical case of a core/shell CdSe/ZnS semiconductor quantum dot which shows a complete suppression of the energy transfer for specific transitions which could not be captured by Förster theory.

  17. Calibration of excitation function measurement based on corona cage test results.

    Science.gov (United States)

    Lan, Lei; Chen, Xiaoyue; Wen, Xishan; Li, Wei; Xiao, Guozhou

    2016-11-01

    Corona cage approaches are crucial for research on the corona characteristics of conductors. Calibration is an indispensable task for determining excitation functions, which are used to predict corona performance of long transmission lines through extrapolation from measurements of short lines in corona cages. In this paper, the amplification factor G is calculated through a frequently adopted method, propagation analysis of high-frequency corona current along a short line. Another convenient calibration method, based on distributed parameter equivalent circuits, is established. The results for G obtained through propagation analysis and equivalent circuits are compared. To verify the rationality of calculation parameters in propagation analysis and equivalent circuits, a calibration experiment based on the excitation caused by a simulated monopulse current was performed. The results of the proposed calibration method and the calibration experiment are in good agreement.

  18. A relativistic time-dependent density functional study of the excited states of the mercury dimer

    Energy Technology Data Exchange (ETDEWEB)

    Kullie, Ossama, E-mail: kullie@uni-kassel.de, E-mail: ossama.kullie@unistra.fr [Institute de Chimie de Strasbourg, CNRS et Université de Strasbourg, Laboratoire de Chimie Quantique, 4 rue Blaise Pascal, 67070 Strasbourg, France and Theoretical Physics, Institute for Physics, Department of Mathematics and Natural Science, University of Kassel, D-34127 Kassel (Germany)

    2014-01-14

    In previous works on Zn{sub 2} and Cd{sub 2} dimers we found that the long-range corrected CAMB3LYP gives better results than other density functional approximations for the excited states, especially in the asymptotic region. In this paper, we use it to present a time-dependent density functional (TDDFT) study for the ground-state as well as the excited states corresponding to the (6s{sup 2} + 6s6p), (6s{sup 2} + 6s7s), and (6s{sup 2} + 6s7p) atomic asymptotes for the mercury dimer Hg{sub 2}. We analyze its spectrum obtained from all-electron calculations performed with the relativistic Dirac-Coulomb and relativistic spinfree Hamiltonian as implemented in DIRAC-PACKAGE. A comparison with the literature is given as far as available. Our result is excellent for the most of the lower excited states and very encouraging for the higher excited states, it shows generally good agreements with experimental results and outperforms other theoretical results. This enables us to give a detailed analysis of the spectrum of the Hg{sub 2} including a comparative analysis with the lighter dimers of the group 12, Cd{sub 2}, and Zn{sub 2}, especially for the relativistic effects, the spin-orbit interaction, and the performance of CAMB3LYP and is enlightened for similar systems. The result shows, as expected, that spinfree Hamiltonian is less efficient than Dirac-Coulomb Hamiltonian for systems containing heavy elements such as Hg{sub 2}.

  19. Excited State Studies of Polyacenes Using the All-Order Constricted Variational Density Functional Theory with Orbital Relaxation.

    Science.gov (United States)

    Senn, Florian; Krykunov, Mykhaylo

    2015-10-22

    For the polyacenes series from naphthalene to hexacene, we present the vertical singlet excitation energies 1 (1)La and 1 (1)Lb, as well as the first triplet excitation energies obtained by the all-order constricted variational density functional theory with orbital relaxation (R-CV(∞)-DFT). R-CV(∞)-DFT is a further development of variational density functional theory (CV(∞)-DFT), which has already been successfully applied for the calculation of the vertical singlet excitation energies (1)La and (1)Lb for polyacenes,15 and we show that one obtains consistent excitation energies using the local density approximation as a functional for singlet as well as for triplet excitations when going beyond the linear response theory. Furthermore, we apply self-consistent field density functional theory (ΔSCF-DFT) and compare the obtained excitation energies for the first triplet excitations T1, where, due to the character of the transition, ΔSCF-DFT and R-CV(∞)-DFT become numerically equivalent, and for the singlet excitations 1 (1)La and 1 (1)Lb, where the two methods differ.

  20. Fabrication of Al/Al3Ti Functionally Graded Materials by Reaction Centrifugal Mixed-Powder Method

    Science.gov (United States)

    El-Hadad, Shimaa; Sato, Hisashi; Miura-Fujiwara, Eri; Watanabe, Yoshimi

    2011-01-01

    Formation of compositional gradient in Al/Al3Ti Functionally graded materials (FGMs) fabricated by the centrifugal method (CM) depends mainly on the centrifugal force and the processing temperature. In this study, a novel centrifugal method, reaction centrifugal mixed-powder method (RCMPM), was proposed to fabricate Al/Al3Ti FGMs under fixed centrifugal force (G=80). The effects of RCMPM processing temperature on the formation of Al3Ti intermetallics, its morphology and its distribution in the fabricated Al/Al3Ti FGMs have been investigated. Fine granular Al3Ti were observed at relatively lower processing temperature while the known coarse platelet-like particles of Al3Ti could be achieved at higher casting temperatures. Moreover, Ti3Al intermetallics compound and unreacted Ti phases are also observed along with Al3Ti particles. In addition, distribution of Al3Ti intermetallics size and their volume fraction showed a significant change when the Al/Al3Ti FGMs processed at different temperatures relative to the liquidus temperature of the master alloy.

  1. Excitation and ionization energies of substituted anilines calculated with density functional theory

    Directory of Open Access Journals (Sweden)

    Yuji Takahata

    2010-06-01

    Full Text Available Valence electron singlet excitation energies (VEExE, valence electron ionization energies (VEIE, core electron binding energies (CEBE, and non-resonant X-ray emission energies of substituted anilines and related molecules were calculated using density functional theory (DFT. The energy calculations were done with TZP basis set of Slater Type Orbitals. PW86x-PW91c, turned out to be the best XC functional among eight functionals tested for time dependent DFT (TDDFT calculation of the singlet excitation energies of the substituted anilines. Using the XC functional, average absolute deviation (AAD from experiment was 0.223 eV for eighteen cases with maximum absolute deviation of 0.932 eV. The valence electron ionization energies of the substituted benzenes were calculated by ΔSCF method with PW86x-PW91c. AAD from experiment was 0.21 eV. The CEBEs were calculated with the previously established method, named as scheme 2003. ΔCEBE(SMS,, sum of mono substituted (SMS CEBE shift, and mutual interference effect (MIE were defined and their values were calculated. Magnitude of MIE provides the degree of mutual interference between two substituents in a phenyl ring. Average absolute value of MIE was ca. 0.1 eV for the three isomers of phenetidine. Using the calculated valence electron ionization energies and the core electron binding energies of one of the phenetidines, some X-ray emission energies were calculated.

  2. Excited state dynamics in In0.5Al0.04Ga0.46As/Al0.08Ga0.92As self-assembled quantum dots

    DEFF Research Database (Denmark)

    Smith, L.M.; Leosson, Kristjan; Østergaard, John Erland;

    2001-01-01

    We use time-resolved photoluminescence spectroscopy to probe the relaxation of excited states in In0.5Al0.04Ga0.40As/Al0.08Ga0.92As self-assembled quantum dots. The relaxation rate of excitons confined to the quantum dots increases by nearly an order of magnitude as the energy of the states appro...

  3. Beyond Time-Dependent Density Functional Theory Using Only Single Excitations: Methods for Computational Studies of Excited States in Complex Systems.

    Science.gov (United States)

    Herbert, John M; Zhang, Xing; Morrison, Adrian F; Liu, Jie

    2016-05-17

    Single-excitation methods, namely, configuration interaction singles and time-dependent density functional theory (TDDFT), along with semiempirical versions thereof, represent the most computationally affordable electronic structure methods for describing electronically excited states, scaling as [Formula: see text] absent further approximations. This relatively low cost, combined with a treatment of electron correlation, has made TDDFT the most widely used excited-state quantum chemistry method over the past 20+ years. Nevertheless, certain inherent problems (beyond just the accuracy of this or that exchange-correlation functional) limit the utility of traditional TDDFT. For one, it affords potential energy surfaces whose topology is incorrect in the vicinity of any conical intersection (CI) that involves the ground state. Since CIs are the conduits for transitions between electronic states, the TDDFT description of photochemistry (internal conversion and intersystem crossing) is therefore suspect. Second, the [Formula: see text] cost can become prohibitive in large systems, especially those that involve multiple electronically coupled chromophores, for example, the antennae structures of light-harvesting complexes or the conjugated polymers used in organic photovoltaics. In such cases, the smallest realistic mimics might already be quite large from the standpoint of ab initio quantum chemistry. This Account describes several new computational methods that address these problems. Topology around a CI can be rigorously corrected using a "spin-flip" version of TDDFT, which involves an α → β spin-flipping transition in addition to occupied → virtual excitation of one electron. Within this formalism, singlet states are generated via excitation from a high-spin triplet reference state, doublets from a quartet, etc. This provides a more balanced treatment of electron correlation between ground and excited states. Spin contamination is problematic away from the

  4. Excitation Function for the 74Se(18O,p3n) Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gates, Jacklyn; Dragojevic, Irena; Dvorak, Jan; Ellison, Paul; Gregorich, Kenneth; Stavsetra, Liv; Nitsche, Heino

    2009-02-02

    The 74Se(18O,p3n)88gNb excitation function was measured and a maximum cross section of 495+-5 mb was observed at and 18O energy of 74.0 MeV. Experimental cross sections were compared to theoretical calculations using the computer code ALICE-91 and the values were found to be in good agreement. The half life of 88gNb was determined to be around 14.56+-0.11 min.

  5. A search for parameters of universal sub-barrier fusion excitation function

    Science.gov (United States)

    Qu, W. W.; Zhang, G. L.; Wolski, R.

    2016-11-01

    Many fusion experimental data have been analyzed in terms of a simple universal function which could be used for predictions of fusion cross section below the barrier for arbitrary systems. Sub-barrier fusions based on the concept of Q -fusion value dependence were studied. It is attempted to parameterize the energy-reduced fusion excitation functions around the Coulomb barriers by an analytical phenomenological function. It was found that the speed of driving nuclei towards fusion is faster with the increase of mass asymmetry of colliding systems and those systems with a large difference of the ratio of neutrons to protons. However, a general trend with respect to total mass has not been observed. An exposition of more qualitative conclusions is hindered by apparent inconsistencies of measured fusion cross sections.

  6. Green's functions for analysis of dynamic response of wheel/rail to vertical excitation

    Science.gov (United States)

    Mazilu, Traian

    2007-09-01

    An analytical model to simulate wheel/rail interaction using the Green's functions method is proposed in this paper. The model consists of a moving wheel on a discretely supported rail. Particularly for this model of rail, the bending and the longitudinal displacement are coupled due to the rail pad and a complex model of the rail pad is adopted. An efficient method for solving a time-domain analysis for wheel/rail interaction is presented. The method is based on the properties of the rail's Green functions and starting to these functions, a track's Green matrix is assembled for the numerical simulations of wheel/rail response due to three kinds of vertical excitations: the steady-state interaction, the rail corrugation and the wheel flat. The study points to influence of the worn rail—rigid contact—on variation in the wheel/rail contact force. The concept of pinned-pinned inhibitive rail pad is also presented.

  7. Electron impact excitation of H{sub 2}: resonance excitation of B {sup 1}{sigma}{sub u}{sup +}(J {sub j}=2, v{sub j}=0) and effective excitation function of EF {sup 1}{sigma}{sub g}{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xianming [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA (United States); Shemansky, D E [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA (United States); Abgrall, H [Observatoire de Paris, Section de Meudon, DAEC and CNRS UMR 8631, 92195 Meudon (France); Roueff, E [Observatoire de Paris, Section de Meudon, DAEC and CNRS UMR 8631, 92195 Meudon (France); Ahmed, S M [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA (United States); Ajello, J M [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA (United States)

    2003-01-28

    The electron impact emission function of the P(3) branch for the (0, 4) band of the H{sub 2} B {sup 1}{sigma}{sub u}{sup +}-X {sup 1}{sigma}{sub g}{sup +} band system has been measured from threshold to 1800 eV. The emission function exhibits structure indicating strong contributions from both resonance and non-resonance excitation. The non-resonance component contains direct and cascade contributions. A combination of experimental and theoretical considerations permits separation of resonance, dipole-allowed direct, dipole-allowed indirect, and dipole-forbidden excitation components for the J{sub j}=2, v{sub j}=0 level of the B {sup 1}{sigma}{sub u}{sup +} state. An effective excitation function for the EF {sup 1}{sigma}{sub g}{sup +}-X {sup 1}{sigma}{sub g}{sup +} band system has been obtained from a nonlinear least-squares analysis of the dipole-forbidden component of the B {sup 1}{sigma}{sub u}{sup +} state emission function. The absolute value of EF {sup 1}{sigma}{sub g}{sup +}-X {sup 1}{sigma}{sub g}{sup +} cross section is established on the basis of earlier experimental results of Liu et al 1995 Astrophys. J. Suppl. 101 375-99 and 2002 Astrophys J. Suppl. 138 229-45 and Abgrall et al 1997 Astrophys. J. 481 557-66 and 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3813-38. A near-threshold apparent resonance excitation cross section of (8.1 {+-} 3.2) x 10{sup -18} cm{sup 2} is obtained for the B {sup 1}{sigma}{sub u}{sup +} (J{sub j}=2 and v{sub j}=0). An EF {sup 1}{sigma}{sub g}{sup +}-X {sup 1}{sigma}{sub g}{sup +} Born cross section has been calculated from the electronic form factor of Kolos et al 1982a J. Chem. Phys. 77 1335-44. Analysis shows that the Born asymptotic shape function of the EF {sup 1}{sigma}{sub g}{sup +}-X {sup 1}{sigma}{sub g}{sup +} band system starts at {approx}400 eV, a significantly higher energy than previously expected. The excitation function is especially important for interpreting outer planet atmospheric dayglow and auroral activity

  8. Neuropeptides function in a homeostatic manner to modulate excitation-inhibition imbalance in C. elegans.

    Science.gov (United States)

    Stawicki, Tamara M; Takayanagi-Kiya, Seika; Zhou, Keming; Jin, Yishi

    2013-05-01

    Neuropeptides play crucial roles in modulating neuronal networks, including changing intrinsic properties of neurons and synaptic efficacy. We previously reported a Caenorhabditis elegans mutant, acr-2(gf), that displays spontaneous convulsions as the result of a gain-of-function mutation in a neuronal nicotinic acetylcholine receptor subunit. The ACR-2 channel is expressed in the cholinergic motor neurons, and acr-2(gf) causes cholinergic overexcitation accompanied by reduced GABAergic inhibition in the locomotor circuit. Here we show that neuropeptides play a homeostatic role that compensates for this excitation-inhibition imbalance in the locomotor circuit. Loss of function in genes required for neuropeptide processing or release of dense core vesicles specifically modulate the convulsion frequency of acr-2(gf). The proprotein convertase EGL-3 is required in the cholinergic motor neurons to restrain convulsions. Electrophysiological recordings of neuromuscular junctions show that loss of egl-3 in acr-2(gf) causes a further reduction of GABAergic inhibition. We identify two neuropeptide encoding genes, flp-1 and flp-18, that together counteract the excitation-inhibition imbalance in acr-2(gf) mutants. We further find that acr-2(gf) causes an increased expression of flp-18 in the ventral cord cholinergic motor neurons and that overexpression of flp-18 reduces the convulsion of acr-2(gf) mutants. The effects of these peptides are in part mediated by two G-protein coupled receptors, NPR-1 and NPR-5. Our data suggest that the chronic overexcitation of the cholinergic motor neurons imposed by acr-2(gf) leads to an increased production of FMRFamide neuropeptides, which act to decrease the activity level of the locomotor circuit, thereby homeostatically modulating the excitation and inhibition imbalance.

  9. Excitation function of elastic $pp$ scattering from a unitarily extended Bialas-Bzdak model

    CERN Document Server

    Nemes, F; Csanád, M

    2014-01-01

    The Bialas-Bzdak model of elastic proton-proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic $pp$ scattering not only at the lower ISR energies but also at $\\sqrt{s}=$7 TeV in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton-proton scattering is predicted for the future LHC energies of $\\sqrt{s}=$8, 13, 14, 15 TeV and also to 28 TeV. A non-trivial, significantly non-exponential feature of the differential cross-section of elastic proton-proton scattering is analyzed and the excitation function of the non-exponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at sma...

  10. Excitation function of elastic $pp$ scattering from a unitarily extended Bialas-Bzdak model

    CERN Document Server

    Nemes, F; Csanád, M

    2015-01-01

    The Bialas-Bzdak model of elastic proton-proton scattering assumes a purely imaginary forward scattering amplitude, which consequently vanishes at the diffractive minima. We extended the model to arbitrarily large real parts in a way that constraints from unitarity are satisfied. The resulting model is able to describe elastic $pp$ scattering not only at the lower ISR energies but also at $\\sqrt{s}=$7~TeV in a statistically acceptable manner, both in the diffractive cone and in the region of the first diffractive minimum. The total cross-section as well as the differential cross-section of elastic proton-proton scattering is predicted for the future LHC energies of $\\sqrt{s}=$13, 14, 15~TeV and also to 28~TeV. A non-trivial, significantly non-exponential feature of the differential cross-section of elastic proton-proton scattering is analyzed and the excitation function of the non-exponential behavior is predicted. The excitation function of the shadow profiles is discussed and related to saturation at small ...

  11. Ground and low-lying excited electronic states of graphene flakes: a density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, Hiroto; Kawabata, Hiroshi, E-mail: hiroto@eng.hokudai.ac.jp [Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)

    2011-10-28

    Structures and electronic states of graphene flakes (finite and small sized graphenes) have been investigated by means of the density functional theory method. Sizes of graphene flakes examined in this study were n = 7, 10, 14, 19, 29 and 44, where n is the number of benzene rings in the graphene flake. The excitation energies of graphene flakes decreased gradually as a function of the number of the ring (n). The orbitals of the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) are localized in the edge region of the graphene flake. It was found that the edge region can react with a water molecule and H{sub 2}O is dissociated into OH radical and hydrogen atom (H) without an activation barrier. A lithium ion can bind strongly to the edge region. The ability of the edge region in the graphene flakes was discussed on the basis of theoretical results.

  12. Laser clad AlSiCuNi functionally graded coatings

    NARCIS (Netherlands)

    Pei, Yutao; de Hosson, J.T.M.; Brebbia, CA

    2001-01-01

    This paper presents an exploration of laser clad AlSiCuNi-alloy FGCs on cast Al-alloy substrates. SEM microstructure observations indicate that, besides Si primary particles, hard Al3Ni2 compounds also exhibits a continuous increase in both particle sizes and volume fractions from the bottom to the

  13. Corrosion behavior of solid solution (Ti,Al)N as a function of Al concentration

    Energy Technology Data Exchange (ETDEWEB)

    Larijani, M.M.; Seyedi, H. [Nuclear Science and Technology Research Institute, P. O. Box 31485-498, Karaj (Iran, Islamic Republic of); Manouchehrian, M. [Department of Physics, Science Faculty, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Yari, M. [Engineering Department Materials, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2012-08-15

    In this work, a series of (Ti, Al) N coatings with different Al contents were deposited on 304 stainless steel substrates by Hollow Cathode Discharge (HCD) method. The coatings were grown on 304 stainless steel substrates at 400 C. The coatings were characterized using energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM), and microhardness test. The XRD confirmed the transition from TiN phase to (Ti, Al) N phase and then to AlN phase with increasing Al concentration in the solid solution. It was found that with increasing Al concentration the hardness of the coatings initially increased up to a maximum value of about 30 GPa at around 32 at.% of Al and then the coating hardness decreased rapidly with further increase of Al content (Al > 32 at.%). The potentiodynamic polarization analysis was carried out in 3.5 wt.% NaCl solutions to study the corrosion resistance of the coatings. From the corrosion test it can be inferred that the amount of Al atoms in the coatings plays an important role for reducing the corrosion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Investigation on luminescence properties of Eu2+-doped Ba3Al2O5Cl2 phosphor for near-UV-excited white LEDs.

    Science.gov (United States)

    Pawade, V B; Dhoble, S J

    2012-01-01

    Ba3Al2O5Cl2:Eu(2+) phosphor was prepared by combustion synthesis (CS). The prepared phosphor was excited at 329 nm; the phosphors shows an efficient bluish-green wide-band emission centred at 490 nm, which originates from the 4f(6)d(1)  →  4f(7) transition of Eu(2+) ions. The excitation spectra of the phosphors have a band centred at 329 nm. It was also characterized by XRD, FT-IR for confirmation of phase purity, and FT-IR analysis indicated the vibrations of metal-oxygen (M-O) groups. SEM shows the morphology of the phosphor at the submicron scale. The results indicate that Ba3Al2O5Cl2:Eu(2+) phosphor may be applicable for solid-state lighting purposes.

  15. Mice deficient in the ALS2 gene exhibit lymphopenia and abnormal hematopietic function.

    Science.gov (United States)

    Erie, Elizabeth A; Shim, Hoon; Smith, Aleah L; Lin, Xian; Keyvanfar, Keyvan; Xie, Chengsong; Chen, Jichun; Cai, Huaibin

    2007-01-01

    One form of juvenile onset autosomal recessive amyotrophic lateral sclerosis (ALS2) has been linked to the dysfunction of the ALS2 gene. The ALS2 gene is expressed in lymphoblasts, however, whether ALS2-deficiency affects periphery blood is unclear. Here we report that ALS2 knockout (ALS2(-/-)) mice developed peripheral lymphopenia but had higher proportions of hematopoietic stem and progenitor cells in which the stem cell factor-induced cell proliferation was up-regulated. Our findings reveal a novel function of the ALS2 gene in the lymphopoiesis and hematopoiesis, suggesting that the immune system is involved in the pathogenesis of ALS2.

  16. Spin contamination-free N-electron wave functions in the excitation-based configuration interaction treatment.

    Science.gov (United States)

    Alcoba, Diego R; Torre, Alicia; Lain, Luis; Massaccesi, Gustavo E; Oña, Ofelia B; Capuzzi, Pablo

    2016-07-07

    This work deals with the spin contamination in N-electron wave functions provided by the excitation-based configuration interaction methods. We propose a procedure to ensure a suitable selection of excited N-electron Slater determinants with respect to a given reference determinant, required in these schemes. The procedure guarantees the construction of N-electron wave functions which are eigenfunctions of the spin-squared operator Sˆ(2), avoiding any spin contamination. Our treatment is based on the evaluation of the excitation level of the determinants by means of the expectation value of an excitation operator formulated in terms of spin-free replacement operators. We report numerical determinations of energies and 〈Sˆ(2)〉 expectation values, arising from our proposal as well as from traditional configuration interaction methods, in selected open-shell systems, in order to compare the behavior of these procedures and their computational costs.

  17. Multiconfiguration Pair-Density Functional Theory Outperforms Kohn-Sham Density Functional Theory and Multireference Perturbation Theory for Ground-State and Excited-State Charge Transfer.

    Science.gov (United States)

    Ghosh, Soumen; Sonnenberger, Andrew L; Hoyer, Chad E; Truhlar, Donald G; Gagliardi, Laura

    2015-08-11

    The correct description of charge transfer in ground and excited states is very important for molecular interactions, photochemistry, electrochemistry, and charge transport, but it is very challenging for Kohn-Sham (KS) density functional theory (DFT). KS-DFT exchange-correlation functionals without nonlocal exchange fail to describe both ground- and excited-state charge transfer properly. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory with a new type of density functional called an on-top density functional. Here we have used MC-PDFT to study challenging ground- and excited-state charge-transfer processes by using on-top density functionals obtained by translating KS exchange-correlation functionals. For ground-state charge transfer, MC-PDFT performs better than either the PBE exchange-correlation functional or CASPT2 wave function theory. For excited-state charge transfer, MC-PDFT (unlike KS-DFT) shows qualitatively correct behavior at long-range with great improvement in predicted excitation energies.

  18. Efficient evaluation of dielectric response functions and calculations of ground and excited state properties beyond local Density Functional approaches

    Science.gov (United States)

    Lu, Deyu; Li, Yan; Rocca, Dario; Viet Nguyen, H.; Gygi, Francois; Galli, Giulia

    2010-03-01

    A recently developed technique to diagonalize iteratively dielectric matrices [1], is used to carry out efficient, ab-initio calculations of dispersion interactions, and excited state properties of nanostructures. In particular, we present results for the binding energies of weakly bonded molecular crystals [2], obtained at the EXX/RPA level of theory, and for absorption spectra of semiconducting clusters, obtained by an iterative solution of the Bethe-Salpeter equations [3]. We show that the ability to obtain the eigenmodes of dielectric matrices from Density Functional perturbation theory, without computing single particle excited states, greatly improves the efficiency of both EXX/RPA and many body perturbation theory [3,4] calculations and opens the way to large scale computations. [1] H. Wilson, F. Gygi and G. Galli, Phys. Rev. B , 78, 113303, 2008; and H. Wilson, D. Lu, F. Gygi and G. Galli, Phys. Rev. B, 79, 245106, 2009. [2] D. Lu, Y. Li, D. Rocca and G. Galli, Phys. Rev. Lett, 102, 206411, 2009; and Y. Li, D. Lu, V. Nguyen and G. Galli, J. Phys. Chem. C (submitted) [3] D. Rocca, D. Lu and G. Galli, submitted. [4] D. Lu, F. Gygi and G. Galli, Phys. Rev. Lett. 100, 147601, 2008. Work was funded by DOE/Scidac DE-FC02-06ER25794 and DOE/BES DE-FG02-06ER46262.

  19. The thermotidal exciting function for water vapour absorption of solar radiation

    Directory of Open Access Journals (Sweden)

    M. BONAFEDE

    1976-06-01

    Full Text Available The thermotidal exciting function J is considered, for
    the absorption of solar radiation by water vapour, according to the model
    derived by Siebert. The Mugge-Moller formula for water vapour absorption
    is integrated numerically, using experimental data for the water vapour
    concentration in the troposphere and the stratosphere. It appears that
    Siebort's formula is a reasonable approximation at low tropospheric levels
    but it dramatically overestimates the water vapour thermotidal heating
    in the upper troposphere and in the stratosphere. It seems thus possible
    that, if the correct vertical profile is employed for J , the amplitudes and
    phases of the diurnal temperature oscillations and of the tidal wind speeds
    may suffer significant changes from those previously calculated and possibly explain the three hours delay of the observed phases from the computed values.

  20. Excitation functions of parameters in Erlang distribution, Schwinger mechanism, and Tsallis statistics in RHIC BES program

    CERN Document Server

    Gao, Li-Na; Lacey, Roy A

    2016-01-01

    Experimental results of the transverse momentum distributions of phi mesons and $\\Omega$ hyperons produced in gold-gold (Au-Au) collisions with different centrality intervals, measured by the STAR Collaboration at different energies (7.7, 11.5, 19.6, 27, and 39 GeV) in the beam energy scan (BES) program at the relativistic heavy ion collider (RHIC), are approximately described by the single Erlang distribution and the two-component Schwinger mechanism. Meanwhile, the STAR experimental transverse momentum distributions of negatively charged particles, produced in Au-Au collisions at RHIC BES energies, are approximately described by the two-component Erlang distribution and the single Tsallis statistics. The excitation functions of free parameters are obtained from the fit to the experimental data. A weak softest point in the string tension in $\\Omega$ hyperon spectra is observed at 7.7 GeV.

  1. Excitation functions of parameters in Erlang distribution, Schwinger mechanism, and Tsallis statistics in RHIC BES program

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Li-Na; Liu, Fu-Hu [Shanxi University, Institute of Theoretical Physics, Shanxi (China); Lacey, Roy A. [Stony Brook University, Departments of Chemistry and Physics, Stony Brook, NY (United States)

    2016-05-15

    Experimental results of the transverse-momentum distributions of φ mesons and Ω hyperons produced in gold-gold (Au-Au) collisions with different centrality intervals, measured by the STAR Collaboration at different energies (7.7, 11.5, 19.6, 27, and 39 GeV) in the beam energy scan (BES) program at the relativistic heavy-ion collider (RHIC), are approximately described by the single Erlang distribution and the two-component Schwinger mechanism. Moreover, the STAR experimental transverse-momentum distributions of negatively charged particles, produced in Au-Au collisions at RHIC BES energies, are approximately described by the two-component Erlang distribution and the single Tsallis statistics. The excitation functions of free parameters are obtained from the fit to the experimental data. A weak softest point in the string tension in Ω hyperon spectra is observed at 7.7 GeV. (orig.)

  2. Candida albicans Agglutinin-Like Sequence (Als Family Vignettes: a Review of Als Protein Structure and Function

    Directory of Open Access Journals (Sweden)

    Lois L. Hoyer

    2016-03-01

    Full Text Available Approximately two decades have passed since the description of the first gene in the Candida albicans ALS (agglutinin-like sequence family. Since that time, much has been learned about the composition of the family and the function of its encoded cell-surface glycoproteins. Solution of the structure of the Als adhesive domain provides the opportunity to evaluate the molecular basis for protein function. This review article is formatted as a series of fundamental questions and explores the diversity of the Als proteins, as well as their role in ligand binding, aggregative effects, and attachment to abiotic surfaces. Interaction of Als proteins with each other, their functional equivalence, and the effects of protein abundance on phenotypic conclusions are also examined. Structural features of Als proteins that may facilitate invasive function are considered. Conclusions that are firmly supported by the literature are presented while highlighting areas that require additional investigation to reveal basic features of the Als proteins, their relatedness to each other, and their roles in C. albicans biology.

  3. A separately excited synchronous motor as high efficient drive in electric vehicles; Die stromerregte Synchronmaschine als hocheffizienter Traktionsmotor in Elektrofahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Illiano, Enzo [ETH Zuerich, Zurich (Switzerland). Inst. fuer Werkzeugmaschinen und Fertigung; Brusa Elektronik AG, Sennfeld (Switzerland)

    2013-08-15

    The separately excited synchronous motor has several advantages which make this topology a very promising traction drive for electric vehicles. The comparison of the separately excited motor with other common topologies also shows the proper regulation of the current in the rotor will rise the complexity of the entire system. In addition the presence of a rotor current has a negative effect on the continuous power of the motor, as the investigations of ETH Zuerich and Brusa show. An optimised motor regulation and an accurate rotor shape design are indispensible to reduce the power deficit. (orig.)

  4. Linear interpolation method in ensemble Kohn-Sham and range-separated density-functional approximations for excited states

    CERN Document Server

    Senjean, Bruno; Jensen, Hans Jørgen Aa; Fromager, Emmanuel

    2015-01-01

    The computation of excitation energies in range-separated ensemble density-functional theory (DFT) is discussed. The latter approach is appealing as it enables the rigorous formulation of a multi-determinant state-averaged DFT method. In the exact theory, the short-range density functional, that complements the long-range wavefunction-based ensemble energy contribution, should vary with the ensemble weights even when the density is held fixed. This weight dependence ensures that the range-separated ensemble energy varies linearly with the ensemble weights. When the (weight-independent) ground-state short-range exchange-correlation functional is used in this context, curvature appears thus leading to an approximate weight-dependent excitation energy. In order to obtain unambiguous approximate excitation energies, we simply propose to interpolate linearly the ensemble energy between equiensembles. It is shown that such a linear interpolation method (LIM) effectively introduces weight dependence effects. LIM has...

  5. Linear interpolation method in ensemble Kohn-Sham and range-separated density-functional approximations for excited states

    DEFF Research Database (Denmark)

    Senjean, Bruno; Knecht, Stefan; Jensen, Hans Jørgen Aa

    2015-01-01

    of range separation and use of the slope of the linearly interpolated ensemble energy, rather than orbital energies. The range-separated approach is appealing, as it enables the rigorous formulation of a multideterminant state-averaged DFT method. In the exact theory, the short-range density functional......-independent) ground-state short-range exchange-correlation functional is used in this context, curvature appears, thus leading to an approximate weight-dependent excitation energy. In order to obtain unambiguous approximate excitation energies, we propose to interpolate linearly the ensemble energy between...... promising results have been obtained for both single (including charge transfer) and double excitations with spin-independent short-range local and semilocal functionals. Even at the Kohn-Sham ensemble DFT level, which is recovered when the range-separation parameter is set to 0, LIM performs better than...

  6. Influence of Exchange-Correlation Functional in the Calculations of Vertical Excitation Energies of Halogenated Copper Phthalocyanines using Time-Dependent Density Functional Theory (TD-DFT)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Uck [Univ. of Ulsan, Ulsan (Korea, Republic of)

    2013-08-15

    The accurate prediction of vertical excitation energies is very important for the development of new materials in the dye and pigment industry. A time-dependent density functional theory (TD-DFT) approach coupled with 22 different exchange-correlation functionals was used for the prediction of vertical excitation energies in the halogenated copper phthalocyanine molecules in order to find the most appropriate functional and to determine the accuracy of the prediction of the absorption wavelength and observed spectral shifts. Among the tested functional, B3LYP functional provides much more accurate vertical excitation energies and UV-vis spectra. Our results clearly provide a benchmark calibration of the TD-DFT method for phthalocyanine based dyes and pigments used in industry.

  7. Decoherence in Optically Excited Semiconductors: a perspective from non-equilibrium Green functions

    Science.gov (United States)

    Virk, Kuljit Singh

    Decoherence is central to our understanding of the transition from the quantum to the classical world. It is also a way of probing the dynamics of interacting many-body systems. Photoexcited semiconductors are such systems in which the transient dynamics can be studied in considerable detail experimentally. Recent advances in spectroscopy of semiconductors provide powerful tools to explore many-body physics in new regimes. An appropriate theoretical framework is necessary to describe new physical effects now accessible for observation. We present a possible approach in this thesis, and discuss results of its application to an experimentally relevant scenario. The major portion of this thesis is devoted to a formalism for the multi-dimensional Fourier spectroscopy of semiconductors. A perturbative treatment of the electromagnetic field is used to derive a closed set of differential equations for the multi-particle correlation functions, which take into account the many-body effects up to third order in the field. A diagrammatic method is developed, in which we retain all features of the double-sided Feynman diagrams for bookkeeping the excitation scenario, and complement them by allowing for the description of interactions. We apply the formalism to study decoherence between the states of optically excited excitons embedded in an electron gas, and compare it with the decoherence between these states and the ground state. We derive a dynamical equation for the two-time correlation functions of excitons, and compare it with the corresponding equation for the interband polarization. It is argued, and verified by numerical calculation, that the decay of Raman coherence depends sensitively on how differently the superimposed exciton states interact with the electron gas, and that it can be much slower than the decay of interband polarization. We also present a new numerical approach based on the length gauge for modeling the time-dependent laser-semiconductor interaction

  8. Magnetic structures and excitations in a multiferroic Y-type hexaferrite BaSrCo2Fe11AlO22

    Science.gov (United States)

    Nakajima, Taro; Tokunaga, Yusuke; Matsuda, Masaaki; Dissanayake, Sachith; Fernandez-Baca, Jaime; Kakurai, Kazuhisa; Taguchi, Yasujiro; Tokura, Yoshinori; Arima, Taka-hisa

    2016-11-01

    We have investigated magnetic orders and excitations in a Y-type hexaferrite BaSrCo2Fe11AlO22 (BSCoFAO), which was reported to exhibit spin-driven ferroelectricity at room temperature [S. Hirose, K. Haruki, A. Ando, and T. Kimura, Appl. Phys. Lett. 104, 022907 (2014), 10.1063/1.4862432]. By means of magnetization, electric polarization, and neutron-diffraction measurements using single-crystal samples, we establish a H -T magnetic phase diagram for magnetic field perpendicular to the c axis (H⊥c). This system exhibits an alternating longitudinal conical (ALC) magnetic structure in the ground state, and it turns into a non-co-planar commensurate magnetic order with spin-driven ferroelectricity under H⊥c. The field-induced ferroelectric phase remains as a metastable state after removing magnetic field below ˜250 K. This metastability is the key to understanding of magnetic field reversal of the spin-driven electric polarization in this system. Inelastic polarized neutron-scattering measurements in the ALC phase reveal a magnetic excitation at around 7.5 meV, which is attributed to spin components oscillating in a plane perpendicular to the cone axis. This phasonlike excitation is expected to be an electric-field active magnon, i.e., electromagnon excitation, in terms of the magnetostriction mechanism.

  9. On the persistency of excitation in radial basis function network identification of nonlinear systems.

    Science.gov (United States)

    Gorinevsky, D

    1995-01-01

    Considers radial basis function (RBF) network approximation of a multivariate nonlinear mapping as a linear parametric regression problem. Linear recursive identification algorithms applied to this problem are known to converge, provided the regressor vector sequence has the persistency of excitation (PE) property. The main contribution of this paper is formulation and proof of PE conditions on the input variables. In the RBF network identification, the regressor vector is a nonlinear function of these input variables. According to the formulated condition, the inputs provide PE, if they belong to domains around the network node centers. For a two-input network with Gaussian RBF that have typical width and are centered on a regular mesh, these domains cover about 25% of the input domain volume. The authors further generalize the proposed solution of the standard RBF network identification problem and study affine RBF network identification that is important for affine nonlinear system control. For the affine RBF network, the author formulates and proves a PE condition on both the system state parameters and control inputs.

  10. Effects of cerebellar transcranial alternating current stimulation on motor cortex excitability and motor function.

    Science.gov (United States)

    Naro, Antonino; Bramanti, Alessia; Leo, Antonino; Manuli, Alfredo; Sciarrone, Francesca; Russo, Margherita; Bramanti, Placido; Calabrò, Rocco Salvatore

    2017-01-07

    The cerebellum regulates several motor functions through two main mechanisms, the cerebellum-brain inhibition (CBI) and the motor surround inhibition (MSI). Although the exact cerebellar structures and functions involved in such processes are partially known, Purkinje cells (PC) and their surrounding interneuronal networks may play a pivotal role concerning CBI and MSI. Cerebellar transcranial alternating current stimulation (tACS) has been proven to shape specific cerebellar components in a feasible, safe, effective, and non-invasive manner. The aim of our study was to characterize the cerebellar structures and functions subtending CBI and MSI using a tACS approach. Fifteen healthy individuals underwent a cerebellar tACS protocol at 10, 50, and 300 Hz, or a sham-tACS over the right cerebellar hemisphere. We measured the tACS aftereffects on motor-evoked potential (MEP) amplitude, CBI induced by tACS (tiCBI) at different frequencies, MSI, and hand motor task performance. None of the participants had any side effect related to tACS. After 50-Hz tACS, we observed a clear tiCBI-50Hz weakening (about +30%, p  0.6). Our preliminary data suggest that PC may represent the last mediator of tiCBI and that the surrounding interneuronal network may have an important role in updating MSI, tiCBI, and M1 excitability during tonic muscle contraction, by acting onto the PC. The knowledge of these neurophysiological issues offers new cues to design innovative, non-invasive neuromodulation protocols to shape cerebellar-cerebral functions.

  11. Excitation function of elliptic flow in Au+Au collisions and the nuclear matter equation of state

    CERN Document Server

    Andronic, A; Basrak, Z; Bastid, N; Benabderrahmane, L; Berek, G; Caplar, R; Cordier, E; Crochet, Philippe; Dupieux, P; Dzelalija, M; Fodor, Z; Gasparic, I; Grishkin, Yu; Hartmann, O N; Herrmann, N; Hildenbrand, K D; Hong, B; Kecskeméti, J; Kim, Y J; Kirejczyk, M; Koczón, P; Korolija, M; Kotte, R; Kress, T; Lebedev, A; Leifels, Y; López, X; Mangiarotti, A; Merschmeyer, M; Neubert, W; Pelte, D; Petrovici, M; Rami, F; Reisdorf, W; de Schauenburg, B; Schüttauf, A; Seres, Z; Sikora, B; Sim, K S; Simion, V; Siwek-Wilczynska, K; Smolyankin, V T; Stockmeier, M R; Stoicea, G; Tyminski, Z; Wagner, P; Wisniewski, K; Wohlfarth, D; Xiao, Z G; Yushmanov, I E; Zhilin, A

    2005-01-01

    We present measurements of the excitation function of elliptic flow at midrapidity in Au+Au collisions at beam energies from 0.09 to 1.49 GeV per nucleon. For the integral flow, we discuss the interplay between collective expansion and spectator shadowing for three centrality classes. A complete excitation function of transverse momentum dependence of elliptic flow is presented for the first time in this energy range, revealing a rapid change with incident energy below 0.4 AGeV, followed by an almost perfect scaling at the higher energies. The equation of state of compressed nuclear matter is addressed through comparisons to microscopic transport model calculations.

  12. Performance of popular XC-functionals for the description of excitation energies in GFP-like chromophore models

    DEFF Research Database (Denmark)

    List, Nanna Holmegaard; Olsen, Jógvan Magnus; Rocha-Rinza, Tomás

    2012-01-01

    Understanding and rationalization of the optical properties of fluorescent proteins are of great importance for life sciences due to their numerous applications as fluorescent biomarkers. Time-dependent density functional theory (TD-DFT) is a computationally appealing approach to accomplish...... this task. We present an evaluation of the performance of commonly used XC-functionals for the prediction of excitation energies of GFP-like chromophores. In particular, we have considered the TD-DFT vertical excitation energies of chromophores displaying different charge states. We compare the quality...

  13. Ghost interaction correction in ensemble density-functional theory for excited states with and without range separation

    CERN Document Server

    Alam, Md Mehboob; Fromager, Emmanuel

    2016-01-01

    Ensemble density-functional theory (eDFT) suffers from the "ghost-interaction" (GI) error when approximate exchange-correlation functionals are used. In this letter, we present a rigorous GI correction (GIC) in the context of multideterminantal range-separated eDFT. The method, which relies on a double generalized adiabatic connection for ensembles, is equally applicable to standard Kohn-Sham eDFT. We show that GIC reduces the curvature of approximate ensemble energies drastically while providing considerably more accurate excitation energies, even for charge-transfer and double excitations.

  14. Magnetophonon resonance in photoluminescence excitation spectra of magnetoexcitons in GaAs/Al0.3Ga0.7As superlattice

    DEFF Research Database (Denmark)

    Dickmann, S.; Tartakovskii, A. I.; Timofeev, V. B.;

    2000-01-01

    to the sample layers. While varying B, the intensities of the PLE peaks have been measured as functions of energy separation Delta E between excited ME peaks and the ground state of the system. The resonance profiles have been found to have maxima at Delta E-max close to the energy of the GaAs LO phonon....... However, the value of Delta E-max depends on quantum numbers of the excited ME state. The revealed very low quantum efficiency of the investigated sample allows us to ascribe the observed resonance to the enhancement of the nonradiative magnetoexciton relaxation rate arising due to LO-phonon emission....... The presented theoretical model, being in a good agreement with experimental observations, provides a method to extract 1sHH magnetoexciton "in-plane" dispersion from the dependence of Delta E-max on the excited ME state quantum numbers....

  15. Vertical electric field induced suppression of fine structure splitting of excited state excitons in a single GaAs/AlGaAs island quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ghali, Mohsen [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Laboratory of Nanophotonics, Physics Department, Faculty of Science, Kafrelsheikh University, 33516 Kafrelsheikh (Egypt); Ohno, Yuzo; Ohno, Hideo [Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

    2015-09-21

    We report experimentally on fine structure splitting (FSS) of various excitonic transitions in single GaAs island quantum dots, formed by a monolayer thickness fluctuation in the narrow GaAs/AlGaAs quantum well, and embedded in an n-i-Schottky diode device. By applying a forward vertical electric field (F) between the top metallic contact and the sample substrate, we observed an in-plane polarization rotation of both the ground and the excited state excitons with increasing the electric field. The polarization rotations were accompanied with a strong decrease in the FSS of the ground as well as the excited state excitons with the field, until the FSS vanished as F approached 30 kV/cm.

  16. Relativistic time-dependent density functional theory, a study of the ground and excited states of the zinc dimer

    Energy Technology Data Exchange (ETDEWEB)

    Kullie, Ossama [CNRS et Universite de Strasbourg, Institut de Chimie, Laboratoire de Chimie Quantique, 1 Rue Blaise Pascal, F- 67008 Strasbourg cedex (France)

    2012-07-01

    In this poster I present a (time-dependent) density functional study of the 20 low-lying excited states as well the ground states of the zinc dimer Zn{sub 2}. I analyze the spectrum of the dimer obtained form all electrons calculations which are performed using time-depended density functional with a relativistic 4-components-, and spin-free-Hamiltonian. I show results for different well-known density functional approximations, in comparing with literature and experimental values, the results are very encouraging, especially for the lowest excited states of these dimers. However, the results show that only the long-range corrected functionals such CAMB3LYP gives the correct asymptotic behavior for the higher states, for which the best result is obtained, and a comparable result is obtained from PBE0 functional.

  17. A ΔE-E Telescope with Ionization Chamber Used in Excitation Function Measurement

    Institute of Scientific and Technical Information of China (English)

    LiSonglin; WangQi; DongYuchuan; XuHuagen; ChenRuofu

    2003-01-01

    A thorough study of excitation function in dissipative heavy ion collision requires the identification of the nuclear charge number Z of the reaction products. For this purpose, a special designed ΔE-E telescope is employed, which consists of a gas filled ionization chamber to detect the energy loss and a position sensitive semiconductor Si detector (300μm in thickness and 8 mm×45 mm in active area) as the residual energy detector. The ionization chamber with a sensitive length of about 60 mm, is divided into two parts of ΔE1 and ΔE2, each with length of 30 mm. The trajectory of the incident particles is parallel to the direction of the electric field in the ionization chamber. The anodes of ΔE1 and ΔE2 are realized through the rectangular empty metallic frames. In order to collect ionized charge produced by the incident particle inside the ionization chamber effectively, two equipotential frame-shape electrodes were placed on both sides of each anode, to form a strong electric focused field toward the anode. The advantages of this type of the detector arc as follows: (1)lower energy detection threshold; (2) wide dynamical range both for the light particles and the heavy fragments;(3) larger solid angle coverage with a relatively smaller detector size based on the position information from the Si detector.

  18. A narrow structure in the excitation function of eta-photoproduction off the neutron

    CERN Document Server

    Werthmueller, D; Keshelashvili, I; Aguar-Bartolome, P; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Kaeser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E F; Metag, V; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P

    2013-01-01

    The photoproduction of $\\eta$-mesons off nucleons bound in $^2$H and $^3$He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the $\\eta\\rightarrow 2\\gamma$ and $\\eta\\rightarrow 3\\pi^0$ decays and the recoil nucleons were detected with an almost $4\\pi$ electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of $\\gamma n\\rightarrow n\\eta$. The results from the two measurements are consistent taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are $W$ = (1670$\\pm$5) MeV and $\\Gamma$ =(30$\\pm$15) MeV. For the first time precise results for the angular dependence of this structure have been ext...

  19. A Preliminary Transcranial Magnetic Stimulation Study of Cortical Inhibition and Excitability in High-Functioning Autism and Asperger Disorder

    Science.gov (United States)

    Enticott, Peter G.; Rinehart, Nicole J.; Tonge, Bruce J.; Bradshaw, John L.; Fitzgerald, Paul B.

    2010-01-01

    Aim: Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS). Method: Participants were diagnosed by…

  20. Channels Active in the Excitability of Nerves and Skeletal Muscles across the Neuromuscular Junction: Basic Function and Pathophysiology

    Science.gov (United States)

    Goodman, Barbara E.

    2008-01-01

    Ion channels are essential for the basic physiological function of excitable cells such as nerve, skeletal, cardiac, and smooth muscle cells. Mutations in genes that encode ion channels have been identified to cause various diseases and disorders known as channelopathies. An understanding of how individual ion channels are involved in the…

  1. Excitation functions for nuclear reactions with interaction of up to 47-MeV deuterons with tin

    Energy Technology Data Exchange (ETDEWEB)

    Gonchar, A.V.; Kondratev, S.N.; Lobach, Y.N.; Nevskii, S.V.; Sklyarenko, V.D.; Tokarevskii, V.V. [Institute of Nuclear Research (Russian Federation)

    1994-03-01

    The investigations, initiated in, of the deuteron excitation functions for nuclear reactions with interaction energies of up to several tens of MeV were continued. The aim of the investigations is to obtain experimental data that can be used to determine the concentration of nuclides forming as a result of the transmutation of nuclei of the deuteron-irradiated material as well as to study the possibilities of predicting the data theoretically. In the present work we measured the excitation function for reactions in which long-lived nuclides are formed under irradiation of tin by deuterons. Calculations of the excitation functions were performed on the basis of the model of pre-equilibrium emission of nucleons and evaporation of nucleons and {gamma}-rays from the compound nucleus using the program ALICE LIVERMORE. Conclusions are drawn on the basis of a comparison of the measurements and calculations about the role of the compound-nucleus mechanism in reactions with deuterons on tin and the possibility of using the ALICE LIVERMORE program for predicting reaction excitation functions. Thus far the only such investigation for tin is the experiment performed with deuteron energies up to 13.6 MeV.

  2. Tuning of the excited state properties of phenylenevinylene oligomers : A time-dependent density functional theory study

    NARCIS (Netherlands)

    Grozema, FC; Telesca, R; Snijders, JG; Siebbeles, LDA

    2003-01-01

    This paper discusses a time-dependent density functional theory study of the effect of molecular structure on the excited state polarizability of conjugated molecules. A short phenylenevinylene oligomer containing three phenyl rings (PV2, distyryl benzene) is taken as a model system. Introduction of

  3. Relative importance of energy dependent diffuseness parameter and barrier position in the analysis of fusion excitation function data

    Directory of Open Access Journals (Sweden)

    Kharab Rajesh

    2014-03-01

    Full Text Available We have investigated the relative importance of the energy dependence of diffuseness parameter and barrier position in the description of the fusion excitation function data of some heavy ion systems in near barrier energy region. The effects of the energy dependent diffuseness parameter are found to be much more prominent in comparison to those of barrier position.

  4. Density functional theory study of neutral AlSn(n = 2-9) clusters

    Institute of Scientific and Technical Information of China (English)

    Li Ting-Xin; Wang Lin; Wang Fei; Chen Jun; Jiang Zhen-Yi; Li Li-Sha

    2011-01-01

    This paper investigates the geometrical structures and relative stabilities of neutral AlSn(n = 2-9) using the density functional theory. Structural optimisation and frequency analysis are performed at the B3LYP/6-311G(d) level. The ground state structures of the AlSn show that the sulfur atoms prefer not only to evenly distribute on both sides of the aluminum atom but also to form stable structures in AlSn clusters. The structures of pure Sn are fundamentally changed due to the doping of the Al atom. The fragmentation energies and the second-order energy differences are calculated and discussed. Among neutral AlSn(n = 2-9) clusters, AlS4 and AlS6 are the most stable.

  5. Change of Work Function of Pd, Ag, K on Al(001) as a Function of External Electric Field

    Institute of Scientific and Technical Information of China (English)

    侯柱峰; 黄美纯; 朱梓忠; 黄荣彬; 郑兰荪

    2001-01-01

    We present a local density functional calculation of the effect of an external electric field on the work function change of Pd and Ag adsorption on an Al(001) surface. The adsorption of K has also been considered for comparison. We found that the work functions for all the systems increased linearly when the strength of the external electric field was increased. Since the polarized electrons at the interstitial regions between the adsorbate and substrate for Pd/Al(001) and Ag/Al(001) react to the external electric field differently, the subtle differences between Pd/Al(001) and Ag/Al(001) bondings has been characterized through the comparison of the slopes of the work function change versus electric field.

  6. Aromatic Lateral Substituents Influence the Excitation Energies of Hexaaza Lanthanide Macrocyclic Complexes: A Wave Function Theory and Density Functional Study.

    Science.gov (United States)

    Rabanal-León, Walter A; Murillo-López, Juliana A; Páez-Hernández, Dayán; Arratia-Pérez, Ramiro

    2015-09-24

    The high interest in lanthanide chemistry, and particularly in their luminescence, has been encouraged by the need of understanding the lanthanide chemical coordination and how the design of new luminescent materials can be affected by this. This work is focused on the understanding of the electronic structure, bonding nature, and optical properties of a set of lanthanide hexaaza macrocyclic complexes, which can lead to potential optical applications. Here we found that the DFT ground state of the open-shell complexes are mainly characterized by the manifold of low lying f states, having small HOMO-LUMO energy gaps. The results obtained from the wave function theory calculations (SO-RASSI) put on evidence the multiconfigurational character of their ground state and it is observed that the large spin-orbit coupling and the weak crystal field produce a strong mix of the ground and the excited states. The electron localization function (ELF) and the energy decomposition analysis (EDA) support the idea of a dative interaction between the macrocyclic ligand and the lanthanide center for all the studied systems; noting that, this interaction has a covalent character, where the d-orbital participation is evidenced from NBO analysis, leaving the f shell completely noninteracting in the chemical bonding. From the optical part we observed in all cases the characteristic intraligand (IL) (π-π*) and ligand to metal charge-transfer (LMCT) bands that are present in the ultraviolet and visible regions, and for the open-shell complexes we found the inherent f-f electronic transitions on the visible and near-infrared region.

  7. Potential Functions of Al2 by the Relativistic Fock-Space Coupled Cluster Method

    Directory of Open Access Journals (Sweden)

    Uzi Kaldor

    2002-05-01

    Full Text Available Abstract: Potential functions of the ground and low excited states of Al2 are calculated by the relativistic Fock-space coupled cluster method in the framework of the projected Dirac-Coulomb Hamiltonian. A moderate-size basis [16s11p3d3f/6s6p3d2f] is used. 3Πu is confirmed as the ground state of the system. Its spin orbit splittings are reproduced well, with the Λ = 1, 2 states lying 32.5 and 66.1 cm−1, respectively, above the Λ = 0 minimum (experimental values are 30.4 and 63.4 cm−1. The bond is somewhat too weak, with De 0.14 eV below experiment, Re too high by 0.08 ˚A, and ωe 21 cm−1 too low. It is speculated that the better agreement obtained in earlier calculations may be due to neglect of basis set superposition errors. The description of bonding in the molecule may be improved by the use of a better basis and the inclusion of more correlation by the intermediate Hamiltonian coupled cluster method, which makes it possible to handle larger P spaces and extend the potential functions to the whole range of internuclear separations.

  8. Excited-state absorption of Cr3+ in LiCaAlF6: Effects of asymmetric distortions and intensity selection rules

    Science.gov (United States)

    Lee, H. W. H.; Payne, Stephen A.; Chase, L. L.

    1989-05-01

    We have measured the π-polarized excited-state absorption (ESA) spectra of the new laser material, LiCaAlF6:Cr3+ (hereafter, Cr3+:LiCAF). We have found that the peak cross section of the ESA band is 0.17×10-20 cm2. We are therefore able to explain the high efficiency previously observed for the Cr3+:LiCAF laser by noting that the peak emission cross section of 1.3×10-20 cm2 is much larger than this ESA cross section. As a result, the ESA does not diminish the value of the effective stimulated-emission cross section, in spite of its tendency to overlap the emission band in most Cr3+-doped crystals. It is then shown that the ESA transition is weak relative to the emission band because the t2u distortion present at the Al3+ site where the Cr3+ substitutes adds transition strength to the π-polarized 4A2-4T2 absorption and emission features, while it does not contribute oscillator strength to the ESA band. The 4T2-->4T1a ESA band is found to peak near 10 030 cm-1, rather than near 7600 cm-1 as expected on the basis of simple crystal-field theory. This is explained as being due to the influence of non-totally-symmetric distortions in the excited states of Cr3+.

  9. exciting: a full-potential all-electron package implementing density-functional theory and many-body perturbation theory

    Science.gov (United States)

    Gulans, Andris; Kontur, Stefan; Meisenbichler, Christian; Nabok, Dmitrii; Pavone, Pasquale; Rigamonti, Santiago; Sagmeister, Stephan; Werner, Ute; Draxl, Claudia

    2014-09-01

    Linearized augmented planewave methods are known as the most precise numerical schemes for solving the Kohn-Sham equations of density-functional theory (DFT). In this review, we describe how this method is realized in the all-electron full-potential computer package, exciting. We emphasize the variety of different related basis sets, subsumed as (linearized) augmented planewave plus local orbital methods, discussing their pros and cons and we show that extremely high accuracy (microhartrees) can be achieved if the basis is chosen carefully. As the name of the code suggests, exciting is not restricted to ground-state calculations, but has a major focus on excited-state properties. It includes time-dependent DFT in the linear-response regime with various static and dynamical exchange-correlation kernels. These are preferably used to compute optical and electron-loss spectra for metals, molecules and semiconductors with weak electron-hole interactions. exciting makes use of many-body perturbation theory for charged and neutral excitations. To obtain the quasi-particle band structure, the GW approach is implemented in the single-shot approximation, known as G0W0. Optical absorption spectra for valence and core excitations are handled by the solution of the Bethe-Salpeter equation, which allows for the description of strongly bound excitons. Besides these aspects concerning methodology, we demonstrate the broad range of possible applications by prototypical examples, comprising elastic properties, phonons, thermal-expansion coefficients, dielectric tensors and loss functions, magneto-optical Kerr effect, core-level spectra and more.

  10. Hydrogen sulfide regulates cardiovascular function by influencing the excitability of subfornical organ neurons.

    Directory of Open Access Journals (Sweden)

    Markus Kuksis

    Full Text Available Hydrogen sulfide (H2S, a gasotransmitter endogenously found in the central nervous system, has recently been suggested to act as a signalling molecule in the brain having beneficial effects on cardiovascular function. This study was thus undertaken to investigate the effect of NaHS (an H2S donor in the subfornical organ (SFO, a central nervous system site important to blood pressure regulation. We used male Sprague-Dawley rats for both in vivo and in vitro experiments. We first used RT-PCR to confirm our previous microarray analyses showing that mRNAs for the enzymes required to produce H2S are expressed in the SFO. We then used microinjection techniques to investigate the physiological effects of NaHS in SFO, and found that NaHS microinjection (5 nmol significantly increased blood pressure (mean AUC = 853.5±105.7 mmHg*s, n = 5. Further, we used patch-clamp electrophysiology and found that 97.8% (88 of 90 of neurons depolarized in response to NaHS. This response was found to be concentration dependent with an EC50 of 35.6 µM. Coupled with the depolarized membrane potential, we observed an overall increase in neuronal excitability using an analysis of rheobase and action potential firing patterns. This study has provided the first evidence of NaHS and thus H2S actions and their cellular correlates in SFO, implicating this brain area as a site where H2S may act to control blood pressure.

  11. Altered neuronal excitability underlies impaired hippocampal function in an animal model of psychosis

    Directory of Open Access Journals (Sweden)

    Thomas eGrüter

    2015-05-01

    Full Text Available Psychosis is accompanied by severe attentional deficits, and impairments in associational-memory processing and sensory information processing that are ascribed to dysfunctions in prefrontal and hippocampal function. Disruptions of glutamatergic signalling may underlie these alterations: Antagonism of the N-methyl-D-aspartate receptor (NMDAR results in similar molecular, cellular, cognitive and behavioural changes in rodents and/or humans as those that occur in psychosis, raising the question as to whether changes in glutamatergic transmission may be intrinsic to the pathophysiology of the disease. In an animal model of psychosis that comprises treatment with the irreversible NMDAR-antagonist, MK801, we explored the cellular mechanisms that may underlie hippocampal dysfunction in psychosis. MK801-treatment resulted in a profound loss of hippocampal LTP that was evident 4 weeks after treatment. Whereas neuronal expression of the immediate early gene, Arc, was enhanced in the hippocampus by spatial learning in controls, MK801-treated animals failed to show activity-dependent increases in Arc expression. By contrast, a significant increase in basal Arc expression in the absence of learning was evident compared to controls. Paired-pulse facilitation was increased at the 40 ms interval indicating that NMDAR and/or fast GABAergic-mediated neurotransmission was disrupted. In line with this, MK801-treatment resulted in a significant decrease in GABA(A, and increase in GABA(B-receptor-expression in PFC, along with a significant increase of GABA(B- and NMDAR-GluN2B expression in the dentate gyrus. NMDAR-GluN1 or GluN2A subunit expression was unchanged. These data suggest that in psychosis, deficits in hippocampus-dependent memory may be caused by a loss of hippocampal LTP that arises through enhanced hippocampal neuronal excitability, altered GluN2B and GABA receptor expression and an uncoupling of the hippocampus-prefrontal cortex circuitry.

  12. Altered neuronal excitability underlies impaired hippocampal function in an animal model of psychosis

    Science.gov (United States)

    Grüter, Thomas; Wiescholleck, Valentina; Dubovyk, Valentyna; Aliane, Verena; Manahan-Vaughan, Denise

    2015-01-01

    Psychosis is accompanied by severe attentional deficits, and impairments in associational-memory processing and sensory information processing that are ascribed to dysfunctions in prefrontal and hippocampal function. Disruptions of glutamatergic signaling may underlie these alterations: Antagonism of the N-methyl-D-aspartate receptor (NMDAR) results in similar molecular, cellular, cognitive and behavioral changes in rodents and/or humans as those that occur in psychosis, raising the question as to whether changes in glutamatergic transmission may be intrinsic to the pathophysiology of the disease. In an animal model of psychosis that comprises treatment with the irreversible NMDAR-antagonist, MK801, we explored the cellular mechanisms that may underlie hippocampal dysfunction in psychosis. MK801-treatment resulted in a profound loss of hippocampal LTP that was evident 4 weeks after treatment. Whereas neuronal expression of the immediate early gene, Arc, was enhanced in the hippocampus by spatial learning in controls, MK801-treated animals failed to show activity-dependent increases in Arc expression. By contrast, a significant increase in basal Arc expression in the absence of learning was evident compared to controls. Paired-pulse (PP) facilitation was increased at the 40 ms interval indicating that NMDAR and/or fast GABAergic-mediated neurotransmission was disrupted. In line with this, MK801-treatment resulted in a significant decrease in GABA(A), and increase in GABA(B)-receptor-expression in PFC, along with a significant increase of GABA(B)- and NMDAR-GluN2B expression in the dentate gyrus. NMDAR-GluN1 or GluN2A subunit expression was unchanged. These data suggest that in psychosis, deficits in hippocampus-dependent memory may be caused by a loss of hippocampal LTP that arises through enhanced hippocampal neuronal excitability, altered GluN2B and GABA receptor expression and an uncoupling of the hippocampus-prefrontal cortex circuitry. PMID:26042007

  13. Hydrogen sulfide regulates cardiovascular function by influencing the excitability of subfornical organ neurons.

    Science.gov (United States)

    Kuksis, Markus; Smith, Pauline M; Ferguson, Alastair V

    2014-01-01

    Hydrogen sulfide (H2S), a gasotransmitter endogenously found in the central nervous system, has recently been suggested to act as a signalling molecule in the brain having beneficial effects on cardiovascular function. This study was thus undertaken to investigate the effect of NaHS (an H2S donor) in the subfornical organ (SFO), a central nervous system site important to blood pressure regulation. We used male Sprague-Dawley rats for both in vivo and in vitro experiments. We first used RT-PCR to confirm our previous microarray analyses showing that mRNAs for the enzymes required to produce H2S are expressed in the SFO. We then used microinjection techniques to investigate the physiological effects of NaHS in SFO, and found that NaHS microinjection (5 nmol) significantly increased blood pressure (mean AUC = 853.5±105.7 mmHg*s, n = 5). Further, we used patch-clamp electrophysiology and found that 97.8% (88 of 90) of neurons depolarized in response to NaHS. This response was found to be concentration dependent with an EC50 of 35.6 µM. Coupled with the depolarized membrane potential, we observed an overall increase in neuronal excitability using an analysis of rheobase and action potential firing patterns. This study has provided the first evidence of NaHS and thus H2S actions and their cellular correlates in SFO, implicating this brain area as a site where H2S may act to control blood pressure.

  14. Osteoblast functions in functionally graded Ti-6Al-4 V mesh structures.

    Science.gov (United States)

    Nune, K C; Kumar, A; Misra, R D K; Li, S J; Hao, Y L; Yang, R

    2016-03-01

    We describe here the combined efforts of engineering and biological sciences as a systemic approach to fundamentally elucidate osteoblast functions in functionally graded Ti-6Al-4 V mesh structures in relation to uniform/monolithic mesh arrays. First, the interconnecting porous architecture of functionally graded mesh arrays was conducive to cellular functions including attachment, proliferation, and mineralization. The underlying reason is that the graded fabricated structure with cells seeded from the large pore size side provided a channel for efficient transfer of nutrients to other end of the structure (small pore size), leading to the generation of mineralized extracellular matrix by differentiating pre-osteoblasts. Second, a comparative and parametric study indicated that gradient mesh structure had a pronounced effect on cell adhesion and mineralization, and strongly influenced the proliferation phase. High intensity and near-uniform distribution of proteins (actin and vinculin) on struts of the gradient mesh structure (cells seeded from large pore side) implied signal transduction during cell adhesion and was responsible for superior cellular activity, in comparison to the uniform mesh structure and non-porous titanium alloy. Cells adhered to the mesh struts by forming a sheet, bridging the pores through numerous cytoplasmic extensions, in the case of porous mesh structures. Intercellular interaction in porous structures provided a pathway for cells to communicate and mature to a differentiated phenotype. Furthermore, the capability of cells to migrate through the interconnecting porous architecture on mesh structures led to colonization of the entire structure. Cells were embedded layer-by-layer in the extracellular matrix as the matrix mineralized. The outcomes of the study are expected to address challenges associated with the treatment of segmental bone defects and bone-remodeling through favorable modulation of cellular response. Moreover, the study

  15. Ghost-interaction correction in ensemble density-functional theory for excited states with and without range separation

    Science.gov (United States)

    Alam, Md. Mehboob; Knecht, Stefan; Fromager, Emmanuel

    2016-07-01

    Ensemble density-functional theory (eDFT) suffers from the so-called "ghost-interaction" error when approximate exchange-correlation functionals are used. In this work, we present a rigorous ghost-interaction correction (GIC) scheme in the context of range-separated eDFT. The method relies on an exact decomposition of the ensemble short-range exchange-correlation energy into a multideterminantal exact exchange term, which involves the long-range interacting ensemble density matrix, instead of the Kohn-Sham (KS) one, and a complementary density-functional correlation energy. A generalized adiabatic connection formula is derived for the latter. In order to perform practical calculations, the complementary correlation functional is simply modeled by its ground-state local density approximation (LDA), while long-range interacting ground- and excited-state wave functions are obtained self-consistently by combining a long-range configuration-interaction calculation with a short-range LDA potential. We show that the GIC reduces the curvature of approximate range-separated ensemble energies drastically while providing considerably more accurate excitation energies, even for charge-transfer and double excitations. Interestingly, the method performs well also in the context of standard KS-eDFT, which is recovered when the range-separation parameter is set to 0.

  16. The effect of Al segregation on Schottky barrier height and effective work function in TiAl/TiN/HfO2 gate stacks

    Science.gov (United States)

    Kim, Geun-Myeong; Oh, Young Jun; Chang, K. J.

    2016-07-01

    We perform first-principles density functional calculations to investigate the effects of Al incorporation on the p-type Schottky barrier height ≤ft({φ\\text{p}}\\right) and the effective work function for various high-k/metal gate stacks, such as TiN/HfO2 with interface Al impurities, Ti1-x Al x N/HfO2, and TiAl/TiN/HfO2. When Al atoms substitute for the interface Ti atoms at TiN/HfO2 interface, interface dipole fields become stronger, leading to the increase of {φ\\text{p}} and thereby the n-type shift of effective work function. In Ti1-x Al x N/HfO2 interface, {φ\\text{p}} linearly increases with the Al content, attributed to the presence of interface Al atoms. On the other hand, in TiAl/TiN/HfO2 interface, where Al is assumed not to segregate from TiAl to TiN, {φ\\text{p}} is nearly independent of the thickness of TiAl. Our results indicate that Al impurities at the metal/dielectric interface play an important role in controlling the effective work function, and provide a clue to understanding the n-type shift of the effective work function observed in TiAl/TiN/HfO2 gate stacks fabricated by using thegate-last process.

  17. Excitation functions of proton induced reactions on {sup nat}Os up to 65 MeV: Experiments and comparison with results from theoretical codes

    Energy Technology Data Exchange (ETDEWEB)

    Hermanne, A.; Adam Rebeles, R. [Cyclotron Laboratory, Vrije Universiteit Brussel, Brussels 1090 (Belgium); Tárkányi, F.; Takács, S. [Institute of Nuclear Research, Hungarian Academy of Science, 4026 Debrecen (Hungary)

    2015-02-15

    Activation of thin {sup nat}Os targets, electrodeposited on Ni backings, was investigated for the first time in stacked foil irradiations with 65 MeV and 34 MeV proton beams. Assessments of the produced radionuclides by high resolution gamma-ray spectroscopy yielded excitation functions for formation of {sup 184,} {sup 185,} {sup 186m,m+g,} {sup 187m+g,} {sup 188m+g,} {sup 189m2+m1+g,} {sup 190m2,m1+g,} {sup 192m1+g}Ir and {sup 185cum,} {sup 191m+g}Os, {sup 183m+g}Re. Where available comparisons with the reaction cross sections obtained in 2 earlier studies on enriched {sup 192}Os were made. Reduced uncertainty on cross sections is obtained by simultaneous remeasurement of the {sup 27}Al(p,x){sup 22,24}Na, {sup nat}Ni(p,x){sup 57}Ni and {sup nat}Ti(p,x){sup 48}V monitor reactions over wide relevant energy ranges. Confirmation of monitoring took place by assessment of excitation functions of {sup 61}Cu, {sup 56}Ni, {sup 55,56,57,58}Co and {sup 52}Mn induced in the Ni backings and comparison with a recent compilation for most of these radionuclides. Contributing reactions and overall cross sections are discussed and were evaluated in comparison with the results of the theoretical code TALYS 1.6 (values from the on-line library TENDL-2013)

  18. Ab initio geometry and bright excitation of carotenoids: Quantum Monte Carlo and Many Body Green's Function Theory calculations on peridinin

    CERN Document Server

    Coccia, Emanuele; Guidoni, Leonardo

    2014-01-01

    In this letter we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) {\\AA}, larger than the values obtained by DFT (PBE, B3LYP and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu+-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu+-like state for the VMC structure (VMC/MBGFT) provide excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.

  19. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory

    Science.gov (United States)

    Sato, Shunsuke A.; Taniguchi, Yasutaka; Shinohara, Yasushi; Yabana, Kazuhiro

    2015-12-01

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases.

  20. Nonlinear electronic excitations in crystalline solids using meta-generalized gradient approximation and hybrid functional in time-dependent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Shunsuke A. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Taniguchi, Yasutaka [Center for Computational Science, University of Tsukuba, Tsukuba 305-8571 (Japan); Department of Medical and General Sciences, Nihon Institute of Medical Science, 1276 Shimogawara, Moroyama-Machi, Iruma-Gun, Saitama 350-0435 (Japan); Shinohara, Yasushi [Max Planck Institute of Microstructure Physics, 06120 Halle (Germany); Yabana, Kazuhiro [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Center for Computational Science, University of Tsukuba, Tsukuba 305-8571 (Japan)

    2015-12-14

    We develop methods to calculate electron dynamics in crystalline solids in real-time time-dependent density functional theory employing exchange-correlation potentials which reproduce band gap energies of dielectrics; a meta-generalized gradient approximation was proposed by Tran and Blaha [Phys. Rev. Lett. 102, 226401 (2009)] (TBm-BJ) and a hybrid functional was proposed by Heyd, Scuseria, and Ernzerhof [J. Chem. Phys. 118, 8207 (2003)] (HSE). In time evolution calculations employing the TB-mBJ potential, we have found it necessary to adopt the predictor-corrector step for a stable time evolution. We have developed a method to evaluate electronic excitation energy without referring to the energy functional which is unknown for the TB-mBJ potential. For the HSE functional, we have developed a method for the operation of the Fock-like term in Fourier space to facilitate efficient use of massive parallel computers equipped with graphic processing units. We compare electronic excitations in silicon and germanium induced by femtosecond laser pulses using the TB-mBJ, HSE, and a simple local density approximation (LDA). At low laser intensities, electronic excitations are found to be sensitive to the band gap energy: they are close to each other using TB-mBJ and HSE and are much smaller in LDA. At high laser intensities close to the damage threshold, electronic excitation energies do not differ much among the three cases.

  1. Communication: Hole localization in Al-doped quartz SiO{sub 2} within ab initio hybrid-functional DFT

    Energy Technology Data Exchange (ETDEWEB)

    Gerosa, Matteo [Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Di Valentin, Cristiana; Pacchioni, Gianfranco [Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R. Cozzi 55, 20125 Milan (Italy); Bottani, Carlo Enrico, E-mail: carlo.bottani@polimi.it [Department of Energy, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Center for Nano Science and Technology @Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy); Onida, Giovanni [Dipartimento di Fisica dell’ Universita’ degli Studi di Milano and European Theoretical Spectroscopy Facility (ETSF), Via Celoria 16, 20133 Milan (Italy)

    2015-09-21

    We investigate the long-standing problem of hole localization at the Al impurity in quartz SiO{sub 2}, using a relatively recent DFT hybrid-functional method in which the exchange fraction is obtained ab initio, based on an analogy with the static many-body COHSEX approximation to the electron self-energy. As the amount of the admixed exact exchange in hybrid functionals has been shown to be determinant for properly capturing the hole localization, this problem constitutes a prototypical benchmark for the accuracy of the method, allowing one to assess to what extent self-interaction effects are avoided. We obtain good results in terms of description of the charge localization and structural distortion around the Al center, improving with respect to the more popular B3LYP hybrid-functional approach. We also discuss the accuracy of computed hyperfine parameters, by comparison with previous calculations based on other self-interaction-free methods, as well as experimental values. We discuss and rationalize the limitations of our approach in computing defect-related excitation energies in low-dielectric-constant insulators.

  2. Excitation functions of (nat)Zn(p,x) nuclear reactions with proton beam energy below 18 MeV.

    Science.gov (United States)

    Asad, Ali H; Chan, Sun; Morandeau, Laurence; Cryer, David; Smith, Suzanne V; Price, Roger I

    2014-12-01

    We measured the excitation functions of (nat)Zn (p,x) reactions up to 17.6MeV, using the stacked-foils activation technique. High-purity natural zinc (and copper) foils were irradiated with proton beams generated by an 18MeV isochronous cyclotron. Activated foils were measured using high-purity Ge gamma spectroscopy to quantify the radionuclides (61)Cu, (66)Ga, (67)Ga, and (65)Zn produced from the reactions. Thick-target integral yields were also deduced from the measured excitation functions of the produced radioisotopes. These results were compared with the published literature and were found to be in good agreement with most reports, particularly those most recently compiled.

  3. Excitation functions for(d,x)reactions on $^{133}$Cs up to $E_d = 40$ MeV

    CERN Document Server

    Tárkányi, F; Takács, S; Hermanne, A; Baba, M; Ignatyuk, A V

    2016-01-01

    In the frame of a systematic study of excitation functions of deuteron induced reactions the excitation functions of the $^{133}$Cs(d,x)$^{133m,133mg,131mg}$Ba, ${134,132}$Cs and $^{129m}$Xe nuclear reactions were measured up to 40 MeV deuteron energies by using the stacked foil irradiation technique and $\\gamma$-ray spectroscopy of activated samples. The results were compared with calculations performed with the theoretical nuclear reaction codes ALICE-IPPE-D, EMPIRE II-D and TALYS calculation listed in the TENDL-2014 library. A moderate agreement was obtained. Based on the integral yields deduced from our measured cross sections, production of $^{131}$Cs via the $^{133}$Cs(d,4n)$^{131}$Ba $\\longrightarrow$ $^{131}$Cs reaction and $^{133}$Ba via $^{133}$Cs(d,2n) reactions is discussed in comparison with other charged particle production routes.

  4. Extension of the excitation functions of deuteron induced reactions on natSn up to 50 MeV

    Science.gov (United States)

    Hermanne, A.; Tárkányi, F.; Ditrói, F.; Takács, S.

    2017-01-01

    Using the stacked-foil activation technique, cross-sections of deuteron induced reactions on natural Sn targets were determined up to 50 MeV. Excitation functions are reported for the product nuclides 116mSb, 117Sb, 118mSb, 120mSb 122m+gSb, 124m+gSb, 110Sn(cum), 113m+gSn(cum), 117mSn, 110mIn(cum), 110gIn, 111m+gIn(cum), 113mIn, 114mIn 115mIn. Comparison with earlier published data at lower energy is discussed. For all excitation functions a theoretical calculation using the TALYS 1.6 (on-line TENDL-2015 library) code is shown.

  5. Excitation Functions of Fusion and Fission for 32S+170Er at Energies Near and Below Coulomb Barrier

    Institute of Scientific and Technical Information of China (English)

    BAO; Peng-fei; LIN; Cheng-jian; YANG; Feng; JIA; Hui-ming; XU; Xin-xing; YANG; Lei; SUN; Li-jie; MA; Nan-ru; ZHANG; Huan-qiao; LIU; Zu-hua

    2013-01-01

    Excitation functions of fusion evaporation residue(ER)and fission for 32S+170Er system at near barrier energy region were measured,respectively.With the comparison to the calculations of coupledchannels effects,it is accessible to investigate the impacts on the fusion and fission processes of target deformation and the dependence on the entrance-channel.The experiment was performed at Beijing HI-13 Tandem Accelerator.Fission and fusion evaporation

  6. Excitation function and isomeric ratio of Tc-isotopes from the {sup 93}Nb(α, xn) reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, G.N., E-mail: gnkim@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Naik, H. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Rediochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Zaman, M. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Yang, S.-C.; Song, T.-Y. [Nuclear Data Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Guin, R.; Das, S.K. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India)

    2015-03-15

    The excitation functions of {sup 94–96}Tc isotopes and independent isomeric ratios of {sup 93m, g}Tc, {sup 94m, g}Tc, and {sup 95m, g}Tc from the {sup 93}Nb(α, xn) reaction within the energy range below 40 MeV have been determined by using a stacked-foil activation and an off-line γ-ray spectrometric technique at the Variable Energy Cyclotron Center, Kolkota, India. The excitation function of {sup 94–96}Tc in the {sup 93}Nb(α, xn) reaction was also calculated by using the computer code TALYS 1.6. The present data are found to be in general agreement with the literature data but have similar trend with some deviation from calculated data of the TALYS 1.6 code. The isomeric ratios of {sup 93m, g}Tc, {sup 94m, g}Tc, and {sup 95m, g}Tc in the {sup 93}Nb(α, xn) reactions from the present work and literature data were compared with similar data in the {sup 93}Nb({sup 3}He, xn) and {sup 96}Mo(p, xn) reactions. In all the three reactions, the isomeric ratios increase with the increasing excitation energy. However, at all excitation energies, the isomeric ratios of {sup 93m, g}Tc, {sup 94m, g}Tc, and {sup 95m, g}Tc in the {sup 93}Nb(α, xn) and {sup 93}Nb({sup 3}He, xn) reactions are higher than those in the {sup 96}Mo(p, xn) reactions, which indicate the role of input angular momentum besides excitation energy. Above the excitation energy of 35–55 MeV, the isomeric ratios of {sup 95m, g}Tc, {sup 94m, g}Tc, and {sup 93m, g}Tc decrease in all the {sup 93}Nb(α, xn), {sup 93}Nb({sup 3}He, xn) and {sup 96}Mo(p, xn) reactions. This decreasing trend at higher excitation energy indicates the starting of pre-equilibrium reaction, which depends on the target, projectile, and type of reaction products.

  7. Variation of Excited-State Dynamics in Trifluoromethyl Functionalized C60 Fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jaehong; Ramirez, Jessica J.; Clikeman, Tyler T.; Larson, Bryon W.; Boltalina, Olga V.; Strauss, Steven H.; Rumbles, Garry

    2016-09-07

    We report on electronically excited-state dynamics of three different trifluoromethyl C60 fullerenes (TMFs, C60(CF3)n: C60/4-1, C60/6-2, and C60/10-1, featuring four, six, and ten trifluoromethyl groups, respectively) using steady-state and time-resolved optical spectroscopy as well as ultrafast pump/probe transient absorption spectroscopy. C60/4-1 and C60/6-2 dissolved in toluene solvent show near-unity S1--T1 intersystem crossing quantum yield (..phi..ISC), ca. 1 ns S1-state lifetimes, and microsecond-timescale T1-state lifetimes, which are typical of the fullerene class. On the other hand, C60/10-1 exhibits a dominant sub-nanosecond nonradiative S1--S0 relaxation mechanism and negligible ..phi..ISC, therefore decreasing the average excited-state lifetime (..tau..avg) by about 5 orders of magnitude compared to that of C60/4-1 and C60/6-2 (..tau..avg approx. 17 us and 54 us for C60/4-1 and C60/6-2, respectively, whereas ..tau..avg approx. 100 ps for C60/10-1). These excited-state characteristics of C60/4-1 and C60/6-2 are preserved in polymer matrix, suggesting that fullerene/polymer interactions do not modulate intrinsic photophysics of trifluoromethyl-substituted fullerenes. The contrasting excited- state study results of C60/4-1 and C60/6-2 to that of C60/10-1 infer that intrinsic optical properties and excited-state dynamics can be affected by the substitution on the fullerene.

  8. Measurement and analysis of excitation functions and observation of mass-asymmetry effect on incomplete fusion dynamics

    Directory of Open Access Journals (Sweden)

    Rashid M.H.

    2011-10-01

    Full Text Available Excitation functions for sixteen evaporation residues produced in the interaction of 20Ne with 165Ho have been measured in the projectile energy range ≈88-164 MeV, using catcher foil activation technique followed by gamma-ray spectrometry. It has been found in general that the excitation functions of evaporation residues produced via xn/pxn channels satisfactorily reproduced with the statistical model code PACE-2 after subtraction of precursor decay contribution. The significant enhancement in the measured excitation functions for the residues produced in alpha emission channels over the PACE-2 predictions has been observed. These alpha emission channels are attributed to incomplete fusion reaction process. The results indicate the occurrence of incomplete fusion involving break-up of projectile 20Ne into 4He + 16O and /or 8Be + 12C followed by fusion of one of the fragments with target nucleus 165Ho. The analysis of the present data suggest that probability of incomplete fusion increases with projectile energy. The ICF fraction FICF also increases with increasing mass-asymmetry of the entrance channel.

  9. Spin transport in undoped InGaAs/AlGaAs multiple quantum well studied via spin photocurrent excited by circularly polarized light.

    Science.gov (United States)

    Zhu, Laipan; Liu, Yu; Huang, Wei; Qin, Xudong; Li, Yuan; Wu, Qing; Chen, Yonghai

    2016-12-01

    The spin diffusion and drift at different excitation wavelengths and different temperatures have been studied in undoped InGaAs/AlGaAs multiple quantum well (MQW). The spin polarization was created by optical spin orientation using circularly polarized light, and the reciprocal spin Hall effect was employed to measure the spin polarization current. We measured the ratio of the spin diffusion coefficient to the mobility of spin-polarized carriers. From the wavelength dependence of the ratio, we found that the spin diffusion and drift of holes became as important as electrons in this undoped MQW, and the ratio for light holes was much smaller than that for heavy holes at room temperature. From the temperature dependence of the ratio, the correction factors for the common Einstein relationship for spin-polarized electrons and heavy holes were firstly obtained to be 93 and 286, respectively.

  10. Double excitations and state-to-state transition dipoles in π-π∗ excited singlet states of linear polyenes: Time-dependent density-functional theory versus multiconfigurational methods

    Science.gov (United States)

    Mikhailov, Ivan A.; Tafur, Sergio; Masunov, Artëm E.

    2008-01-01

    The effect of static and dynamic electron correlation on the nature of excited states and state-to-state transition dipole moments is studied with a multideterminant wave function approach on the example of all-trans linear polyenes ( C4H6 , C6H8 , and C8H10 ). Symmetry-forbidden singlet nAg states were found to separate into three groups: purely single, mostly single, and mostly double excitations. The excited-state absorption spectrum is dominated by two bright transitions: 1Bu-2Ag and 1Bu-mAg , where mAg is the state, corresponding to two-electron excitation from the highest occupied to lowest unoccupied molecular orbital. The richness of the excited-state absorption spectra and strong mixing of the doubly excited determinants into lower- nAg states, reported previously at the complete active space self-consistent field level of theory, were found to be an artifact of the smaller active space, limited to π orbitals. When dynamic σ-π correlation is taken into account, single- and double-excited states become relatively well separated at least at the equilibrium geometry of the ground state. This electronic structure is closely reproduced within time-dependent density-functional theory (TD DFT), where double excitations appear in a second-order coupled electronic oscillator formalism and do not mix with the single excitations obtained within the linear response. An extension of TD DFT is proposed, where the Tamm-Dancoff approximation (TDA) is invoked after the linear response equations are solved (a posteriori TDA). The numerical performance of this extension is validated against multideterminant-wave-function and quadratic-response TD DFT results. It is recommended for use with a sum-over-states approach to predict the nonlinear optical properties of conjugated molecules.

  11. Excited states from range-separated density-functional perturbation theory

    CERN Document Server

    Rebolini, Elisa; Teale, Andrew M; Helgaker, Trygve; Savin, Andreas

    2014-01-01

    We explore the possibility of calculating electronic excited states by using perturbation theory along a range-separated adiabatic connection. Starting from the energies of a partially interacting Hamiltonian, a first-order correction is defined with two variants of perturbation theory: a straight-forward perturbation theory, and an extension of the G{\\"o}rling--Levy one that has the advantage of keeping the ground-state density constant at each order in the perturbation. Only the first, simpler, variant is tested here on the helium and beryllium atoms and on the dihydrogene molecule. The first-order correction within this perturbation theory improves significantly the total ground-and excited-state energies of the different systems. However, the excitation energies are mostly deterio-rated with respect to the zeroth-order ones, which may be explained by the fact that the ionization energy is no longer correct for all interaction strengths. The second variant of the perturbation theory should improve these re...

  12. Residue excitation functions from complete fusion of [sup 16]O with [sup 197]Au and [sup 208]Pb

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, K.; Caraley, A.L.; Fineman, B.J.; Gan, N.; Velkovska, J.; McGrath, R.L. (Physics Department, State University of New York at Stony Brook, Stony Brook, New York 11794 (United States))

    1994-07-01

    Evaporation residue excitation functions and [alpha]-multiplicities from complete fusion of [sup 16]O with [sup 197]Au and [sup 208]Pb have been measured from the fusion threshold up to 140 MeV incident energy. The data allow the conclusion that strongly overdamped motion cannot be dominant at energies in the vicinity of the fusion barrier below [ital E][sup *][approx]50 MeV. At excitation energies above 50 MeV the residue cross section for [sup 16]O+[sup 208]Pb is much greater than predicted from the statistical model with conventional parametrizations. The enhancement is not explained by incorporating dynamical effects into the analysis. An alternative suggestion based on deexcitation-chain dependent fission barriers is discussed.

  13. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  14. Two-photon excited fluorescence of intrinsic fluorophores enables label-free assessment of adipose tissue function

    Science.gov (United States)

    Alonzo, Carlo Amadeo; Karaliota, Sevasti; Pouli, Dimitra; Liu, Zhiyi; Karalis, Katia P.; Georgakoudi, Irene

    2016-08-01

    Current methods for evaluating adipose tissue function are destructive or have low spatial resolution. These limit our ability to assess dynamic changes and heterogeneous responses that occur in healthy or diseased subjects, or during treatment. Here, we demonstrate that intrinsic two-photon excited fluorescence enables functional imaging of adipocyte metabolism with subcellular resolution. Steady-state and time-resolved fluorescence from intracellular metabolic co-factors and lipid droplets can distinguish the functional states of excised white, brown, and cold-induced beige fat. Similar optical changes are identified when white and brown fat are assessed in vivo. Therefore, these studies establish the potential of non-invasive, high resolution, endogenous contrast, two-photon imaging to identify distinct adipose tissue types, monitor their functional state, and characterize heterogeneity of induced responses.

  15. Consistent evaluations of (n,2n) and (n,np) reaction excitation functions for some even-even isotopes using empirical systematics

    Energy Technology Data Exchange (ETDEWEB)

    Manokhin, Vassily N. [Russian Nuclear Data Center, Institute of Physics and Power Engineering, Obninsk (Russian Federation); Odano, Naoteru; Hasegawa, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    An approach for consistent evaluation of (n,2n) and (n,np) reaction excitation functions for some even-even isotopes with the (n,np) reaction thresholds lower than (n,2n) reaction ones is described. For determination of cross sections in the maximum of the (n,2n) and (n,np) reaction excitation functions some empirical systematics developed by Manokhin were used together with trends in dependence of gaps between the (n,2n) and (n,np) thresholds on atomic mass number A. The shapes of the (n,2n) and (n,np) reaction excitation functions were calculated using the normalized functions from the Manokhin's systematics. Excitation functions of (n,2n) and (n,np) reactions were evaluated for several nuclei by using the systematics and it was found that the approach used for the present study gives reasonable results. (author)

  16. Uniform Atomic Layer Deposition of Al2O3 on Graphene by Reversible Hydrogen Plasma Functionalization

    Science.gov (United States)

    2017-01-01

    A novel method to form ultrathin, uniform Al2O3 layers on graphene using reversible hydrogen plasma functionalization followed by atomic layer deposition (ALD) is presented. ALD on pristine graphene is known to be a challenge due to the absence of dangling bonds, leading to nonuniform film coverage. We show that hydrogen plasma functionalization of graphene leads to uniform ALD of closed Al2O3 films down to 8 nm in thickness. Hall measurements and Raman spectroscopy reveal that the hydrogen plasma functionalization is reversible upon Al2O3 ALD and subsequent annealing at 400 °C and in this way does not deteriorate the graphene’s charge carrier mobility. This is in contrast with oxygen plasma functionalization, which can lead to a uniform 5 nm thick closed film, but which is not reversible and leads to a reduction of the charge carrier mobility. Density functional theory (DFT) calculations attribute the uniform growth on both H2 and O2 plasma functionalized graphene to the enhanced adsorption of trimethylaluminum (TMA) on these surfaces. A DFT analysis of the possible reaction pathways for TMA precursor adsorption on hydrogenated graphene predicts a binding mechanism that cleans off the hydrogen functionalities from the surface, which explains the observed reversibility of the hydrogen plasma functionalization upon Al2O3 ALD.

  17. Hole trapping at Al impurities in silica: A challenge for density functional theories

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2001-01-01

    The atomic geometry and electronic structure around a neutral substitutional Al impurity in silica is investigated using either the unrestricted Hartree-Fock (UHF) approximation, or Beckes three-parameter hybrid functional (B3LYP). It is found that the B3LYP functional fails to describe the struc...

  18. Modeling Spin Fluctuations and Magnetic Excitations from Time-Dependent Density Functional Theory

    Science.gov (United States)

    Gorni, Tommaso; Timrov, Iurii; Dal Corso, Andrea; Baroni, Stefano

    Harnessing spin fluctuations and magnetic excitations in materials is key in many fields of technology, spanning from memory devices to information transfer and processing, to name but a few. A proper understanding of the interplay between collective and single-particle spin excitations is still lacking, and it is expected that first-principle simulations based on TDDFT may shed light on this interplay, as well as on the role of important effects such as relativistic ones and related magnetic anisotropies. All the numerical approaches proposed so far to tackle this problem are based on the computationally demanding solution of the Sternheimer equations for the response orbitals or the even more demanding solution of coupled Dyson equations for the spin and charge susceptibilities. The Liouville-Lanczos approach to TDDFT has already proven to be a valuable alternative, the most striking of its features being the avoidance of sums over unoccupied single-particle states and the frequency-independence of the main numerical bottleneck. In this work we present an extension of this methodology to magnetic systems and its implementation in the Quantum ESPRESSO distribution, together with a few preliminary results on the magnon dispersions in bulk Fe.

  19. Diabatic-At-Construction Method for Diabatic and Adiabatic Ground and Excited States Based on Multistate Density Functional Theory.

    Science.gov (United States)

    Grofe, Adam; Qu, Zexing; Truhlar, Donald G; Li, Hui; Gao, Jiali

    2017-03-14

    We describe a diabatic-at-construction (DAC) strategy for defining diabatic states to determine the adiabatic ground and excited electronic states and their potential energy surfaces using the multistate density functional theory (MSDFT). The DAC approach differs in two fundamental ways from the adiabatic-to-diabatic (ATD) procedures that transform a set of preselected adiabatic electronic states to a new representation. (1) The DAC states are defined in the first computation step to form an active space, whose configuration interaction produces the adiabatic ground and excited states in the second step of MSDFT. Thus, they do not result from a similarity transformation of the adiabatic states as in the ATD procedure; they are the basis for producing the adiabatic states. The appropriateness and completeness of the DAC active space can be validated by comparison with experimental observables of the ground and excited states. (2) The DAC diabatic states are defined using the valence bond characters of the asymptotic dissociation limits of the adiabatic states of interest, and they are strictly maintained at all molecular geometries. Consequently, DAC diabatic states have specific and well-defined physical and chemical meanings that can be used for understanding the nature of the adiabatic states and their energetic components. Here we present results for the four lowest singlet states of LiH and compare them to a well-tested ATD diabatization method, namely the 3-fold way; the comparison reveals both similarities and differences between the ATD diabatic states and the orthogonalized DAC diabatic states. Furthermore, MSDFT can provide a quantitative description of the ground and excited states for LiH with multiple strongly and weakly avoided curve crossings spanning over 10 Å of interatomic separation.

  20. The collisional relaxation of highly vibrationally excited molecules: Glimpses of the energy transfer mechanism and distribution function

    Science.gov (United States)

    Michaels, Chris Arthur

    The relaxation of highly vibrationally excited donor molecules, C4H4N2 and C6F6, (E vib ~ 5 eV), by collisions with a bath of CO2 is investigated using high resolution, infrared transient absorption spectroscopy. The vibrationally hot donor molecules are formed by 248 nm excimer laser pumping, followed by rapid radiationless decay to the ground electronic state. This technique yields the nascent bath quantum state distributions following a single donor/bath collision. Absolute energy transfer rates are measured along with the partitioning of energy among the bath degrees of freedom. These measurements provide insight into the nature of the intermolecular forces mediating the energy transfer and allow the construction of energy transfer distribution functions, P(E,E') for these systems. Pyrazine/CO2 collisions which result in the excitation of bath vibrational modes, including the anti- symmetric stretch (0001), the Fermi-mixed symmetric stretch/bending overtone (1000 r1 and 1000 r2) and the unmixed bending overtone (0220), are studied. The vibrational energy transfer is accompanied by very little rotational and translational excitation and displays the characteristic strong, inverse temperature dependence (probability of transfer increases with decreasing temperature) expected of energy transfer mediated by a long range attractive interaction. Collisions between highly vibrationally excited C6F6 and CO2, which result in significant excitation of the bath rotational and translational degrees of freedom, are examined. This type of energy transfer is mediated by the short range repulsive region of the C6F6/CO2 intermolecular potential. A gap law model is used to fit the weak temperature dependence of these scattering processes in an effort to quantify the energy transfer magnitudes. A prescription for mapping bath quantum state resolved energy transfer rate constants onto an energy transfer probability distribution function, P(E,E') is described in detail. Analysis of

  1. Parametrically Excited Oscillations of Second-Order Functional Differential Equations and Application to Duffing Equations with Time Delay Feedback

    Directory of Open Access Journals (Sweden)

    Mervan Pašić

    2014-01-01

    Full Text Available We study oscillatory behaviour of a large class of second-order functional differential equations with three freedom real nonnegative parameters. According to a new oscillation criterion, we show that if at least one of these three parameters is large enough, then the main equation must be oscillatory. As an application, we study a class of Duffing type quasilinear equations with nonlinear time delayed feedback and their oscillations excited by the control gain parameter or amplitude of forcing term. Finally, some open questions and comments are given for the purpose of further study on this topic.

  2. Density functional theory and evolution algorithm calculations of elastic properties of AlON

    Energy Technology Data Exchange (ETDEWEB)

    Batyrev, I. G.; Taylor, D. E.; Gazonas, G. A.; McCauley, J. W. [U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)

    2014-01-14

    Different models for aluminum oxynitride (AlON) were calculated using density functional theory and optimized using an evolutionary algorithm. Evolutionary algorithm and density functional theory (DFT) calculations starting from several models of AlON with different Al or O vacancy locations and different positions for the N atoms relative to the vacancy were carried out. The results show that the constant anion model [McCauley et al., J. Eur. Ceram. Soc. 29(2), 223 (2009)] with a random distribution of N atoms not adjacent to the Al vacancy has the lowest energy configuration. The lowest energy structure is in a reasonable agreement with experimental X-ray diffraction spectra. The optimized structure of a 55 atom unit cell was used to construct 220 and 440 atom models for simulation cells using DFT with a Gaussian basis set. Cubic elastic constant predictions were found to approach the experimentally determined AlON single crystal elastic constants as the model size increased from 55 to 440 atoms. The pressure dependence of the elastic constants found from simulated stress-strain relations were in overall agreement with experimental measurements of polycrystalline and single crystal AlON. Calculated IR intensity and Raman spectra are compared with available experimental data.

  3. A Green's function model for ferromagnetism and spin excitations of (Ga, Mn)As diluted magnetic semiconductors

    Institute of Scientific and Technical Information of China (English)

    Liu Gui-Bin; Liu Bang-Gui

    2009-01-01

    We study (Ga, Mn)As diluted magnetic semiconductors in terms of the Ruderman-Kittel-Kasuya-Yosida quantum spin model in Green's function approach. Random distributions of the magnetic atoms are treated by using an analytical average of magnetic configurations. Average magnetic moments and spin excitation spectra as functions of temperature can be obtained by solving self-consistent equations, and the Curie temperature T_C is given explicitly. T_C is proportional to magnetic atomic concentration, and there exists a maximum for T_C as a function of carrier concentration. Applied to (Ga, Mn)As, the theoretical results are consistent with experiment and the experimental T_C can be obtained with reasonable parameters. This modelling can also be applied to other diluted magnetic semiconductors.

  4. Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule.

    Science.gov (United States)

    Guan, Jingang; Wang, Fan; Ziegler, Tom; Cox, Hazel

    2006-07-28

    Orbital energies, ionization potentials, molecular constants, potential energy curves, and the excitation spectrum of O(2) are calculated using time-dependent density functional theory (TDDFT) with Tamm-Dancoff approximation (TDA). The calculated negative highest occupied molecular orbital energy (-epsilon(HOMO)) is compared with the energy difference ionization potential for five exchange correlation functionals consisting of the local density approximation (LDAxc), gradient corrected Becke exchange plus Perdew correlation (B(88X)+P(86C)), gradient regulated asymptotic correction (GRAC), statistical average of orbital potentials (SAOP), and van Leeuwen and Baerends asymptotically correct potential (LB94). The potential energy curves calculated using TDDFT with the TDA at internuclear distances from 1.0 to 1.8 A are divided into three groups according to the electron configurations. The 1pi(u) (4)1pi(g) (2) electron configuration gives rise to the X (3)Sigma(g) (-), a (1)Delta(g), and b (1)Sigma(g) (+) states; the 1pi(u) (3)1pi(g) (3) electron configuration gives rise to the c (1)Sigma(u) (-), C (3)Delta(u), and A (3)Sigma(u) (+) states; and the B (3)Sigma(u) (-), A (1)Delta(u), and f (1)Sigma(u) (+) states are determined by the mixing of two or more electron configurations. The excitation spectrum of the oxygen molecule, calculated with the aforementioned exchange correlation functionals, shows that the results are quite sensitive to the choice of functional. The LDAxc and the B(88X)+P(86C) functionals produce similar spectroscopic patterns with a single strongly absorbing band positioned at 19.82 and 19.72 eV, respectively, while the asymptotically corrected exchange correlation functionals of the SAOP and the LB94 varieties yield similar excitation spectra where the computed strongly absorbing band is located at 16.09 and 16.42 eV, respectively. However, all of the exchange correlation functionals yield only one strongly absorbing band (oscillator strength

  5. Coupled cluster method with single and double excitations tailored by matrix product state wave functions

    CERN Document Server

    Veis, Libor; Neese, Frank; Legeza, Örs; Pittner, Jiří

    2016-01-01

    We present an alternative method for accurate treatment of strongly correlated systems which combines the coupled cluster (CC) theory with the density matrix renormalization group method (DMRG). The connection is done in the spirit of the tailored CC method [T. Kinoshita, O. Hino, and R. J. Bartlett, \\textit{J. Chem. Phys.} {\\bf 123} (2005) 074106]. In the first step, the configuration interaction (CI) coefficients corresponding to single and double excitations within the DMRG active space are computed by contraction of the matrix product state (MPS) matrices. These coefficients are subsequently transformed into CC amplitudes. In the second step, the CC amplitudes are used to define a "tailored" single reference CCSD wavefunction. As a result, the DMRG method is responsible for the proper description of non-dynamic correlation, whereas the dynamic correlation is incorporated through the framework of the CC theory. We illustrate the potential of this method on prominent multireference model systems like N$_2$ ...

  6. Charge-displacement analysis for excited states

    Energy Technology Data Exchange (ETDEWEB)

    Ronca, Enrico, E-mail: enrico@thch.unipg.it; Tarantelli, Francesco, E-mail: francesco.tarantelli@unipg.it [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia (Italy); Pastore, Mariachiara, E-mail: chiara@thch.unipg.it; Belpassi, Leonardo; De Angelis, Filippo [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Angeli, Celestino; Cimiraglia, Renzo [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)

    2014-02-07

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  7. Luminescence properties of an orange-red phosphor GdAl3(BO3)4:Sm3+ under VUV excitation and energy transfer from Gd3+ to Sm3+

    Science.gov (United States)

    He, Jin; Zhang, Su; Zhou, Jianbang; Zhong, Jiuping; Liang, Hongbin; Sun, Shuaishuai; Huang, Yan; Tao, Ye

    2015-01-01

    In order to develop a new warm-color emission phosphor under vacuum ultraviolet (VUV) excitation, trivalent samarium ion (Sm3+) doped GdAl3(BO3)4 was prepared by a solid state reaction technique at high temperature. The VUV excitation and emission spectra of as-synthesized sample GdAl3(BO3)4:Sm3+ were determined in the Beijing Synchrotron Radiation Facilities (BSRF). Compared with the emission of GdAl3(BO3)4:Eu3+, GdAl3(BO3)4:Sm3+ shows an orange-red emission under Xe 172 nm VUV excitation, which indicates that Sm3+ ion can be a possible activator to obtain warm color emission in the field of lighting. Furthermore, for improving the emission of Sm3+ doped in GdAl3(BO3)4, the energy transfer process from Gd3+ in the host to the activator Sm3+ was investigated through the analysis of spectroscopic characteristics and luminescence decay curves of GdAl3(BO3)4:Sm3+. The results reveal that there exists energy transfer from Gd3+ to Sm3+, but the energy transfer from Sm3+ to Gd3+ is inefficient.

  8. Longest-Wavelength Electronic Excitations of Linear Cyanines: The Role of Electron Delocalization and of Approximations in Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Ii, Barry Moore; Autschbach, Jochen

    2013-11-12

    The lowest-energy/longest-wavelength electronic singlet excitation energies of linear cyanine dyes are examined, using time-dependent density functional theory (TDDFT) and selected wave function methods in comparison with literature data. Variations of the bond-length alternation obtained with different optimized structures produce small differences of the excitation energy in the limit of an infinite chain. Hybrid functionals with range-separated exchange are optimally 'tuned', which is shown to minimize the delocalization error (DE) in the cyanine π systems. Much unlike the case of charge-transfer excitations, small DEs are not strongly correlated with better performance. A representative cyanine is analyzed in detail. Compared with accurate benchmark data, TDDFT with 'pure' local functionals gives too high singlet excitation energies for all systems, but DFT-based ΔSCF calculations with a local functional severely underestimates the energies. TDDFT strongly overestimates the difference between singlet and triplet excitation energies. An analysis points to systematically much too small magnitudes of integrals from the DFT components of the exchange-correlation response kernel as the likely culprit. The findings support previous suggestions that the differential correlation energy between the ground and excited state is not correctly produced by TDDFT with most functionals.

  9. Finite-element multiconfiguration Hartree-Fock calculations of the atomic quadrupole moments of excited states of Be, Al, In, Ne, Ar, Kr, and Xe

    Science.gov (United States)

    Sundholm, Dage; Olsen, Jeppe

    1993-04-01

    The atomic quadrupole moments Qzz of Be(2s2p;3P2), Al(3p;2P3/2), In(5p;2P3/2), Ne(2p53s3P2), Ar(3p54s;3P2), Kr(4p55s;3P2), and Xe(5p56s;3P2) have been calculated using a finite-element multiconfiguration Hartree-Fock method. The obtained Qzz(Be) of 2.265 a.u. agrees with previously calculated values. The calculated Qzz(Al) and Qzz(In) of 2.579 and 3.165 a.u. are in good agreement with the experimental values of 2.53(15) a.u. and 2.94(10) a.u. A large s-d polarization contribution to the Qzz of the rare gases is found in the present calculations. The correlation contributions from double (D), triple (T), and quadruple (Q) excitations to the Qzz of the rare gases alternate; the total DTQ correlation contribution is negligibly small for Ne, Ar, and Kr, while the DTQ correlation contribution to the Qzz(Xe) is 25% of the final Qzz. The final values are Qzz(Ne)=-0.0506 a.u., Qzz(Ar)=-0.0553 a.u., Qzz(Kr)=+0.0601 a.u., and Qzz(Xe)=+0.4505 a.u., as compared to the experimental values of -0.048(5) a.u., -0.042(4) a.u., +0.046(5) a.u., and +0.30(3) a.u. for Ne, Ar, Kr, and Xe, respectively.

  10. Frenkel and Charge-Transfer Excitations in Donor-acceptor Complexes from Many-Body Green's Functions Theory.

    Science.gov (United States)

    Baumeier, Björn; Andrienko, Denis; Rohlfing, Michael

    2012-08-14

    Excited states of donor-acceptor dimers are studied using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. For a series of prototypical small-molecule based pairs, this method predicts energies of local Frenkel and intermolecular charge-transfer excitations with the accuracy of tens of meV. Application to larger systems is possible and allowed us to analyze energy levels and binding energies of excitons in representative dimers of dicyanovinyl-substituted quarterthiophene and fullerene, a donor-acceptor pair used in state of the art organic solar cells. In these dimers, the transition from Frenkel to charge transfer excitons is endothermic and the binding energy of charge transfer excitons is still of the order of 1.5-2 eV. Hence, even such an accurate dimer-based description does not yield internal energetics favorable for the generation of free charges either by thermal energy or an external electric field. These results confirm that, for qualitative predictions of solar cell functionality, accounting for the explicit molecular environment is as important as the accurate knowledge of internal dimer energies.

  11. Exact ensemble density functional theory for excited states in a model system: investigating the weight dependence of the correlation energy

    CERN Document Server

    Deur, Killian; Fromager, Emmanuel

    2016-01-01

    Ensemble density functional theory (eDFT) is an exact time-independent alternative to time-dependent DFT (TD-DFT) for the calculation of excitation energies. Despite its formal simplicity and advantages in contrast to TD-DFT (multiple excitations, for example, can be easily taken into account in an ensemble), eDFT is not standard which is essentially due to the lack of reliable approximate exchange-correlation (xc) functionals for ensembles. Following Burke and coworkers [Phys. Rev. B 93, 245131 (2016)], we propose in this work to construct an exact eDFT for the nontrivial asymmetric Hubbard dimer, thus providing more insight into the weight dependence of the ensemble xc energy in various correlation regimes. For that purpose, an exact analytical expression for the weight-dependent ensemble exchange energy has been derived. The complementary exact ensemble correlation energy has been computed by means of Legendre-Fenchel transforms. Interesting features like discontinuities in the ensemble xc potential in the...

  12. Functional testing of space flight induced changes in tonic motor control by using limb-attached excitation and load devices

    Science.gov (United States)

    Gallasch, Eugen; Kozlovskaya, Inessa

    2007-02-01

    Long term space flights induce atrophy and contractile changes on postural muscles such effecting tonic motor control. Functional testing of tonic motor control structures is a challenge because of the difficulties to deliver appropriate test forces on crew members. In this paper we propose two approaches for functional testing by using limb attached loading devices. The first approach is based on a frequency and amplitude controllable moving magnet exciter to deliver sinusoidal test forces during limb postures. The responding limb deflection is recorded by an embedded accelerometer to obtain limb impedance. The second approach is based on elastic limb loading to evoke self-excited oscillations during arm extensions. Here the contraction force at the oscillation onset provides information about limb stiffness. The rationale for both testing approaches is based on Feldman's λ-model. An arm expander based on the second approach was probed in a 6-month MIR space flight. The results obtained from the load oscillations, confirmed that this device is well suited to capture space flight induced neuromuscular changes.

  13. New excitation functions for proton induced reactions on natural titanium, nickel and copper up to 70 MeV

    Science.gov (United States)

    Garrido, E.; Duchemin, C.; Guertin, A.; Haddad, F.; Michel, N.; Métivier, V.

    2016-09-01

    New excitation functions for proton induced nuclear reactions on natural titanium, nickel and copper were measured, using the stacked-foil technique and gamma spectrometry, up to 70 MeV. The experimental cross sections were measured using the Ti-nat(p,x) V-48, Ni-nat(p,x) Ni-57 and Cu-nat(p,x) Zn-62,Co-56 monitor reactions recommended by the International Atomic Energy Agency (IAEA), depending on the investigated energy range. Data have been extracted for the Ti-nat(p,x) Sc-43,44m,46,47,48, V-48, K-42,43, Ni-nat(p,x) Ni-56,57, Co-55,56,57,58, Mn-52,54, Cu-nat(p,x) Cu-61,64, Ni-57, Co-56,57,58,60, Zn-62,65, Mn-54 reactions. Our results are discussed and compared to the existing ones as well as with the TALYS code version 1.6 calculations using default models. Our experimental data are in overall good agreement with the literature. TALYS is able to reproduce, in most cases, the experimental trend. Our new experimental results allow to expand our knowledge on these excitation functions, to confirm the existing trends and to give additional values on a large energy range. This work is in line with the new Coordinated Research Project (CRP) launched by the IAEA to expand the database of monitor reactions.

  14. Influence of RF excitation during pulsed laser deposition in oxygen atmosphere on the structural properties and luminescence of nanocrystalline ZnO:Al thin films

    Energy Technology Data Exchange (ETDEWEB)

    Meljanac, Daniel, E-mail: dmeljan@irb.hr; Plodinec, Milivoj; Siketić, Zdravko; Gracin, Davor [Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb (Croatia); Juraić, Krunoslav [Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia and Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9/IV, 8010 Graz (Austria); Krstulović, Nikša; Salamon, Krešimir; Skenderović, Hrvoje; Kregar, Zlatko; Rakić, Iva Šrut [Institute of Physics, Bijenička 46, 10000 Zagreb (Croatia); Bernstorff, Sigrid [Elettra-Sincrotrone Trieste, SS 14, Km 163.5, I-34049 Basovizza (TS) (Italy)

    2016-03-15

    Thin ZnO:Al layers were deposited by pulsed laser deposition in vacuum and in oxygen atmosphere at gas pressures between 10 and 70 Pa and by applying radio-frequency (RF) plasma. Grazing incidence small angle x-ray scattering and grazing incidence x-ray diffraction (GIXRD) data showed that an increase in the oxygen pressure leads to an increase in the roughness, a decrease in the sample density, and changes in the size distribution of nanovoids. The nanocrystal sizes estimated from GIXRD were around 20 nm, while the sizes of the nanovoids increased from 1 to 2 nm with the oxygen pressure. The RF plasma mainly influenced the nanostructural properties and point defects dynamics. The photoluminescence consisted of three contributions, ultraviolet (UV), blue emission due to Zn vacancies, and red emission, which are related to an excess of oxygen. The RF excitation lowered the defect level related to blue emission and narrowed the UV luminescence peak, which indicates an improvement of the structural ordering. The observed influence of the deposition conditions on the film properties is discussed as a consequence of two main effects: the variation of the energy transfer from the laser plume to the growing film and changes in the growth chemistry.

  15. Role of physiological ClC-1 Cl- ion channel regulation for the excitability and function of working skeletal muscle

    DEFF Research Database (Denmark)

    Pedersen, Thomas Holm; Riisager, Anders; de Paoli, Frank Vincenzo

    2016-01-01

    temporal resolution in action potential firing muscle fibers. These and other techniques have revealed that ClC-1 function is controlled by multiple cellular signals during muscle activity. Thus, onset of muscle activity triggers ClC-1 inhibition via protein kinase C, intracellular acidosis, and lactate...... permeability for Cl- ions. Thus, in resting human muscle, ClC-1 Cl- ion channels account for ∼80% of the membrane conductance, and because active Cl- transport is limited in muscle fibers, the equilibrium potential for Cl- lies close to the resting membrane potential. These conditions—high membrane conductance...... muscle excitability. Data from ClC-1 expression systems suggest that this ClC-1 activation may arise from loss of regulation by adenosine nucleotides and/or oxidation. The present review summarizes the current knowledge of the physiological factors that control ClC-1 function in active muscle....

  16. Strain and Cohesive Energy of TiN Deposit on Al(001) Surface: Density Functional Calculation

    Science.gov (United States)

    Ren, Yuan; Liu, Xuejie

    2016-07-01

    To apply the high hardness of TiN film to soft and hard multilayer composite sheets, we constructed a new type of composite structural material with ultra-high strength. The strain of crystal and cohesive energy between the atoms in the eight structures of N atom, Ti atom, 2N2Ti island and TiN rock salt deposited on the Al(001) surface were calculated with the first-principle ultra-soft pseudopotential approach of the plane wave based on the density functional theory. The calculations of the cohesive energy showed that N atoms could be deposited in the face-centered-cubic vacancy position of the Al(001) surface and results in a cubic structure AlN surface. The TiN film could be deposited on the interface of β-AlN. The calculations of the strains showed that the strain in the TiN film deposited on the Al(001) surface was less than that in the 2N2Ti island deposited on the Al(001) surface. The diffusion behavior of interface atom N was investigated by a nudged elastic band method. Diffusion energy calculation showed that the N atom hardly diffused to the substrate Al layer.

  17. Potential structural and functional biomarkers of upper motor neuron dysfunction in ALS.

    Science.gov (United States)

    Grieve, Stuart M; Menon, Parvathi; Korgaonkar, Mayuresh S; Gomes, Lavier; Foster, Sheryl; Kiernan, Matthew C; Vucic, Steve

    2015-01-01

    Assessment of upper motor neuron (UMN) function in amyotrophic lateral sclerosis (ALS) remains clinically based. Given the potential difficulties in identifying UMN signs, objective biomarkers of UMN dysfunction are important. Consequently, the present study assessed utility of cortical thickness analysis combined with threshold tracking transcranial magnetic stimulation (TMS) as biomakers of UMN dysfunction in ALS. Cortical thickness analysis and threshold tracking TMS studies were undertaken on 25 ALS patients and results were compared to healthy control subjects, with different control groups used for each technique. Structural and functional abnormalities were evident in both motor cortices in the ALS cohort and were heralded by marked reduction of short-interval intracortical inhibition (SICI RAPB 1.4 ± 2.4%; SICI LAPB 3.6 ± 1.9%; SICI CONTROLS10.5 ± 1.1%, p <0.01), resting motor threshold (p <0.05) and cortical silent period duration (p <0.001) combined with increase in MEP amplitude (p <0.05) and intracortical facilitation (p <0.05). Significant cortical thinning was evident in the bitemporal regions (p <0.05), while precentral gyrus cortical thinning was evident in 56% of cases and when combined with TMS abnormalities disclosed UMN dysfunction in 88% of cases. In conclusion, findings from the present study establish that a combination of structural and functional assessment of corticomotoneurons may increase the yield of objectively identifying UMN dysfunction in ALS.

  18. Faraday waves under time-reversed excitation.

    Science.gov (United States)

    Pietschmann, Dirk; Stannarius, Ralf; Wagner, Christian; John, Thomas

    2013-03-01

    Do parametrically driven systems distinguish periodic excitations that are time mirrors of each other? Faraday waves in a Newtonian fluid are studied under excitation with superimposed harmonic wave forms. We demonstrate that the threshold parameters for the stability of the ground state are insensitive to a time inversion of the driving function. This is a peculiarity of some dynamic systems. The Faraday system shares this property with standard electroconvection in nematic liquid crystals [J. Heuer et al., Phys. Rev. E 78, 036218 (2008)]. In general, time inversion of the excitation affects the asymptotic stability of a parametrically driven system, even when it is described by linear ordinary differential equations. Obviously, the observed symmetry has to be attributed to the particular structure of the underlying differential equation system. The pattern selection of the Faraday waves above threshold, on the other hand, discriminates between time-mirrored excitation functions.

  19. Proteomic analysis of FUS interacting proteins provides insights into FUS function and its role in ALS.

    Science.gov (United States)

    Kamelgarn, Marisa; Chen, Jing; Kuang, Lisha; Arenas, Alexandra; Zhai, Jianjun; Zhu, Haining; Gal, Jozsef

    2016-10-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease. Mutations in the Fused in Sarcoma/Translocated in Liposarcoma (FUS/TLS) gene cause a subset of familial ALS cases and are also implicated in sporadic ALS. FUS is typically localized to the nucleus. The ALS-related FUS mutations cause cytoplasmic mis-localization and the formation of stress granule-like structures. Abnormal cytoplasmic FUS localization was also found in a subset of frontotemporal dementia (FTLD) cases without FUS mutations. To better understand the function of FUS, we performed wild-type and mutant FUS pull-downs followed by proteomic identification of the interacting proteins. The FUS interacting partners we identified are involved in multiple pathways, including chromosomal organization, transcription, RNA splicing, RNA transport, localized translation, and stress response. FUS interacted with hnRNPA1 and Matrin-3, RNA binding proteins whose mutations were also reported to cause familial ALS, suggesting that hnRNPA1 and Matrin-3 may play common pathogenic roles with FUS. The FUS interactions displayed varied RNA dependence. Numerous FUS interacting partners that we identified are components of exosomes. We found that FUS itself was present in exosomes, suggesting that the secretion of FUS might contribute to the cell-to-cell spreading of FUS pathology. FUS interacting proteins were sequestered into the cytoplasmic mutant FUS inclusions that could lead to their mis-regulation or loss of function, contributing to ALS pathogenesis. Our results provide insights into the physiological functions of FUS as well as important pathways where mutant FUS can interfere with cellular processes and potentially contribute to the pathogenesis of ALS.

  20. Parallel transmit excitation at 1.5 T based on the minimization of a driving function for device heating

    Energy Technology Data Exchange (ETDEWEB)

    Gudino, N., E-mail: natalia.gudino@nih.gov [Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Sonmez, M.; Nielles-Vallespin, S.; Faranesh, A. Z.; Lederman, R. J.; Balaban, R. S.; Hansen, M. S. [National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Yao, Z.; Baig, T.; Martens, M. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Griswold, M. A. [Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106 and Department of Radiology, University Hospitals of Cleveland, Cleveland, Ohio 44106 (United States)

    2015-01-15

    Purpose: To provide a rapid method to reduce the radiofrequency (RF) E-field coupling and consequent heating in long conductors in an interventional MRI (iMRI) setup. Methods: A driving function for device heating (W) was defined as the integration of the E-field along the direction of the wire and calculated through a quasistatic approximation. Based on this function, the phases of four independently controlled transmit channels were dynamically changed in a 1.5 T MRI scanner. During the different excitation configurations, the RF induced heating in a nitinol wire immersed in a saline phantom was measured by fiber-optic temperature sensing. Additionally, a minimization of W as a function of phase and amplitude values of the different channels and constrained by the homogeneity of the RF excitation field (B{sub 1}) over a region of interest was proposed and its results tested on the benchtop. To analyze the validity of the proposed method, using a model of the array and phantom setup tested in the scanner, RF fields and SAR maps were calculated through finite-difference time-domain (FDTD) simulations. In addition to phantom experiments, RF induced heating of an active guidewire inserted in a swine was also evaluated. Results: In the phantom experiment, heating at the tip of the device was reduced by 92% when replacing the body coil by an optimized parallel transmit excitation with same nominal flip angle. In the benchtop, up to 90% heating reduction was measured when implementing the constrained minimization algorithm with the additional degree of freedom given by independent amplitude control. The computation of the optimum phase and amplitude values was executed in just 12 s using a standard CPU. The results of the FDTD simulations showed similar trend of the local SAR at the tip of the wire and measured temperature as well as to a quadratic function of W, confirming the validity of the quasistatic approach for the presented problem at 64 MHz. Imaging and heating

  1. On the excited state wave functions of Dirac fermions in the random gauge potential

    Indian Academy of Sciences (India)

    H Milani Moghaddam

    2010-04-01

    In the last decade, it was shown that the Liouville field theory is an effective theory of Dirac fermions in the random gauge potential (FRGP). We show that the Dirac wave functions in FRGP can be written in terms of descendents of the Liouville vertex operator. In the quasiclassical approximation of the Liouville theory, our model predicts 22.2 that the localization length scales with the energy as $ ∼ E^{−b^{2}(1+b^{2})^{2}}$, where is the strength of the disorder. The self-duality of the theory under the transformation → 1/ is discussed. We also calculate the distribution functions of 0 = |0 ()|2, (i.e. (0); 0 () is the ground state wave function), which behaves as the log-normal distribution function. It is also shown that in small 0, (0) behaves as a chi-square distribution.

  2. Can we Predict Quantum Yields Using Excited State Density Functional Theory for New Families of Fluorescent Dyes?

    Science.gov (United States)

    Kohn, Alexander W.; Lin, Zhou; Shepherd, James J.; Van Voorhis, Troy

    2016-06-01

    For a fluorescent dye, the quantum yield characterizes the efficiency of energy transfer from the absorbed light to the emitted fluorescence. In the screening among potential families of dyes, those with higher quantum yields are expected to have more advantages. From the perspective of theoreticians, an efficient prediction of the quantum yield using a universal excited state electronic structure theory is in demand but still challenging. The most representative examples for such excited state theory include time-dependent density functional theory (TDDFT) and restricted open-shell Kohn-Sham (ROKS). In the present study, we explore the possibility of predicting the quantum yields for conventional and new families of organic dyes using a combination of TDDFT and ROKS. We focus on radiative (kr) and nonradiative (knr) rates for the decay of the first singlet excited state (S_1) into the ground state (S_0) in accordance with Kasha's rule. M. Kasha, Discuss. Faraday Soc., 9, 14 (1950). For each dye compound, kr is calculated with the S_1-S_0 energy gap and transition dipole moment obtained using ROKS and TDDFT respectively at the relaxed S_1 geometry. Our predicted kr agrees well with the experimental value, so long as the order of energy levels is correctly predicted. Evaluation of knr is less straightforward as multiple processes are involved. Our study focuses on the S_1-T_1 intersystem crossing (ISC) and the S_1-S_0 internal conversion (IC): we investigate the properties that allow us to model the knr value using a Marcus-like expression, such as the Stokes shift, the reorganization energy, and the S_1-T_1 and S_1-S_0 energy gaps. Taking these factors into consideration, we compare our results with those obtained using the actual Marcus theory and provide explanation for discrepancy. T. Kowalczyk, T. Tsuchimochi, L. Top, P.-T. Chen, and T. Van Voorhis, J. Chem. Phys., 138, 164101 (2013). M. Kasha, Discuss. Faraday Soc., 9, 14 (1950).

  3. Application of the dressed time-dependent density functional theory for the excited states of linear polyenes.

    Science.gov (United States)

    Mazur, Grzegorz; Włodarczyk, Radosław

    2009-04-15

    Dressed Time-Dependent Density Functional Theory (Maitra et al., J Chem Phys 2004, 120, 5932) is applied to selected linear polyenes. Limits of validity of the approximation are briefly discussed. The implementation strategy is described. Results for the 2(1)B(u) and 2(1)A(g) states of selected linear polyenes are presented and compared with accessible experimental and theoretical results.

  4. Formative versus Reflective Measurement in Executive Functions: A Critique of Willoughby et al.

    Science.gov (United States)

    Peterson, Eric; Welsh, Marilyn C.

    2014-01-01

    Research into executive functioning (EF) has indeed grown exponentially across the past few decades, but as the Willoughby et al. critique makes clear, there remain fundamental questions to be resolved. The crux of their argument is built upon an examination of the confirmatory factor analysis (CFA) approach to understanding executive processes.…

  5. SiCp/Ti6Al4V functionally graded materials produced by laser melt injection

    NARCIS (Netherlands)

    Pei, Y.T.; Ocelik, V.; Hosson, J.Th.M. De

    2002-01-01

    With a well-controlled laser melt injection (LMI) process, for the first time the feasibility is demonstrated to produce SiC particles (SiCp) reinforced Ti6Al4V functionally graded materials (FGMs). SiCp are injected just behind the laser beam into the extended part of the laser melt pool that is fo

  6. Five-Fold Branched Si Particles in Laser Clad AlSi Functionally Graded Materials

    NARCIS (Netherlands)

    Pei, Y.T.; Hosson, J.Th.M. De

    2001-01-01

    Many five-fold branched Si particles (Sip) were observed in Al–40 wt% Si functionally graded materials produced by a single-step laser cladding process on cast Al-alloy substrate. In this paper the five-fold twinning and growth features of Sip are scrutinized with orientation imaging microscopy and

  7. A density functional theory study of arsenic immobilization by the Al(III)-modified zeolite clinoptilolite

    NARCIS (Netherlands)

    Awuah, Joel B.; Dzade, N.Y.; Tia, Richard; Adei, Evans; Kwakye-Awuah, Bright; Catlow, C. Richard A.; de Leeuw, Nora H.

    2016-01-01

    We present density functional theory calculations of the adsorption of arsenic acid (AsO(OH)3) and arsenous acid (As(OH)3) on the Al(III)-modified natural zeolite clinoptilolite under anhydrous and hydrated conditions. From our calculated adsorption energies, we show that adsorption of both arsenic

  8. Interrelation of work function and surface stability : The case of BaAl4

    NARCIS (Netherlands)

    Uijttewaal, MA; de Wijs, GA; de Groot, RA; Coehoorn, R; van Elsbergen, [No Value; Weijtens, CHL

    2005-01-01

    The relationship between the work function (Phi) and the surface stability of compounds is, to our knowledge, unknown but very important for applications such as organic light-emitting diodes. This relation is studied using first-principles calculations on various surfaces of BaAl4. The most stable

  9. Molecular and vibrational structure of tetroxo d0 metal complexes in their excited states. a study based on time-dependent density functional calculations and Franck-Condon theory.

    Science.gov (United States)

    Jose, Linta; Seth, Michael; Ziegler, Tom

    2012-02-23

    We have applied time dependent density functional theory to study excited state structures of the tetroxo d(0) transition metal complexes MnO(4)(-), TcO(4)(-), RuO(4), and OsO(4). The excited state geometry optimization was based on a newly implemented scheme [Seth et al. Theor. Chem. Acc. 2011, 129, 331]. The first excited state has a C(3v) geometry for all investigated complexes and is due to a "charge transfer" transition from the oxygen based HOMO to the metal based LUMO. The second excited state can uniformly be characterized by "charge transfer" from the oxygen HOMO-1 to the metal LUMO with a D(2d) geometry for TcO(4)(-), RuO(4), and OsO(4) and two C(2v) geometries for MnO(4)(-). It is finally found that the third excited state of MnO(4)(-) representing the HOMO to metal based LUMO+1 orbital transition has a D(2d) geometry. On the basis of the calculated excited state structures and vibrational modes, the Franck-Condon method was used to simulate the vibronic structure of the absorption spectra for the tetroxo d(0) transition metal complexes. The Franck-Condon scheme seems to reproduce the salient features of the experimental spectra as well as the simulated vibronic structure for MnO(4)(-) generated from an alternative scheme [Neugebauer J. J. Phys. Chem. A 2005, 109, 1168] that does not apply the Franck-Condon approximation.

  10. Tailoring the optimal control cost function to a desired output: application to minimizing phase errors in short broadband excitation pulses

    Science.gov (United States)

    Skinner, Thomas E.; Reiss, Timo O.; Luy, Burkhard; Khaneja, Navin; Glaser, Steffen J.

    2005-01-01

    The de facto standard cost function has been used heretofore to characterize the performance of pulses designed using optimal control theory. The freedom to choose new, creative quality factors designed for specific purposes is demonstrated. While the methodology has more general applicability, its utility is illustrated by comparison to a consistently chosen example—broadband excitation. The resulting pulses are limited to the same maximum RF amplitude used previously and tolerate the same variation in RF homogeneity deemed relevant for standard high-resolution NMR probes. Design criteria are unchanged: transformation of Iz → Ix over resonance offsets of ±20 kHz and RF variability of ±5%, with a peak RF amplitude equal to 17.5 kHz. However, the new cost effectively trades a small increase in residual z magnetization for improved phase in the transverse plane. Compared to previous broadband excitation by optimized pulses (BEBOP), significantly shorter pulses are achievable, with only marginally reduced performance. Simulations transform Iz to greater than 0.98 Ix, with phase deviations of the final magnetization less than 2°, over the targeted ranges of resonance offset and RF variability. Experimental performance is in excellent agreement with the simulations.

  11. [Study of the "stimulus--excitation" function in the peripheral portion of the frog taste analyzer].

    Science.gov (United States)

    Shmarov, D A; Samoĭlov, V O

    1979-04-01

    The intensity of glossopharyngeal nerve afferent discharges in the frog was studied during stimulation of gustatory receptors by caffeine, acetic acid, saccharose and sodium chloride ranging widely in the concentration changes. It was shown, that the function "stimulus-exitation" for the summary discharges in response on the coffeine and acetic acid was being logaryphmic. The character of off-effects dependence on the concentration of bitter and sour stimuli. Was proved to be the same. The curve "stimulus-exitation" for the saccharose was "S" shaped, but for the sodium chloride it might be described by the power function with the exponent equal 0,8.

  12. Unrestricted density functional theory based on the fragment molecular orbital method for the ground and excited state calculations of large systems

    Energy Technology Data Exchange (ETDEWEB)

    Nakata, Hiroya, E-mail: nakata.h.ab@m.titech.ac.jp [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Fedorov, Dmitri G. [NRI, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Yokojima, Satoshi [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tokyo University of Pharmacy and Life Sciences, 1423-1 Horinouchi, Hachioji-shi, Tokyo 192-0392 (Japan); Kitaura, Kazuo [Graduate School of System Informatics, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Sakurai, Minoru [Center for Biological Resources and Informatics, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501 (Japan); Nakamura, Shinichiro [RIKEN, Research Cluster for Innovation, Nakamura Lab, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2014-04-14

    We extended the fragment molecular orbital (FMO) method interfaced with density functional theory (DFT) into spin unrestricted formalism (UDFT) and developed energy gradients for the ground state and single point excited state energies based on time-dependent DFT. The accuracy of FMO is evaluated in comparison to the full calculations without fragmentation. Electronic excitations in solvated organic radicals and in the blue copper protein, plastocyanin (PDB code: 1BXV), are reported. The contributions of solvent molecules to the electronic excitations are analyzed in terms of the fragment polarization and quantum effects such as interfragment charge transfer.

  13. Nonequilibrium Green function theory for excitation and transport in atoms and molecules

    NARCIS (Netherlands)

    Dahlen, Nils Erik; Stan, Adrian

    2006-01-01

    In this work we discuss the application of nonequilibrium Green functions theory to atomic and molecular systems with the aim to study charge and energy transport in these systems. We apply the Kadanoff-Baym equations to atoms and diatomic molecules initially in the ground state. The results obtaine

  14. Cellular mechanisms regulating neuronal excitability: Functional implications and in epilepsy | Mecanismos celulares reguladores de la excitabilidad celular: Implicaciones funcionales y en epilepsia

    OpenAIRE

    Cabezas-Fernández, C.; Martín-Montiel, E. D.; Buño, W

    2003-01-01

    Introduction and method. The cellular mechanisms that regulate neuronal excitability and the propagation of electrical signals in the dendrites of pyramidal neurons are incompletely understood and of key functional and pathological importance. The capacity of dendrites to actively propagate action potentials is vital in processes related to memory and learning. The deregulation of dendritic excitability may also contribute to epilepsy. The contributions of ionic conductances that regulate neu...

  15. Malondialdehyde suppresses cerebral function by breaking homeostasis between excitation and inhibition in turtle Trachemys scripta.

    Directory of Open Access Journals (Sweden)

    Fangxu Li

    Full Text Available The levels of malondialdehyde (MDA are high in the brain during carbonyl stress, such as following daily activities and sleep deprivation. To examine our hypothesis that MDA is one of the major substances in the brain leading to fatigue, the influences of MDA on brain functions and neuronal encodings in red-eared turtle (Trachemys scripta were studied. The intrathecal injections of MDA brought about sleep-like EEG and fatigue-like behaviors in a dose-dependent manner. These changes were found associated with the deterioration of encoding action potentials in cortical neurons. In addition, MDA increased the ratio of γ-aminobutyric acid to glutamate in turtle's brain, as well as the sensitivity of GABAergic neurons to inputs compared to excitatory neurons. Therefore, MDA, as a metabolic product in the brain, may weaken cerebral function during carbonyl stress through breaking the homeostasis between excitatory and inhibitory neurons.

  16. Calculation of excitation functions of the 54,56,57,58Fe(, ) reaction from threshold to 30 MeV

    Indian Academy of Sciences (India)

    Damewan Suchiang; J Joseph Jeremiah; B M Jyrwa

    2014-10-01

    The cross-sections for the formation of 54,56,57,58Co in the 54,56,57,58Fe(, ) reaction from threshold to 30 MeV protons have been theoretically calculated using the TALYS-1.4 nuclear model code, whereby we have studied major nuclear reaction mechanisms, including direct, preequilibrium and compound nuclear reaction. Subsequently, the level density and shell damping parameters have been adjusted and at the same time, the odd–even effects are well comprehended. The excitation functions have been compared with experimental nuclear data. It is observed that the theoretical cross-sections match fairly well. Proton-induced reaction cross-sections provide clues to understand the nuclear structure and offers a good testing ground for ideas about nuclear forces. In addition, complete information in this field is very much required for application in accelerator-driven subcritical system.

  17. Theory of optical excitation and relaxation phenomena at semiconductor surfaces: linking density functional and density matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Buecking, N. [Technische Universitaet Berlin, Institut fuer Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Berlin (Germany); Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Scheffler, M. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany); Kratzer, P. [Universitaet Duisburg-Essen, Fachbereich Physik - Theoretische Physik, Duisburg (Germany); Knorr, A. [Technische Universitaet Berlin, Institut fuer Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Berlin (Germany)

    2007-08-15

    A theory for the description of optical excitation and the subsequent phonon-induced relaxation dynamics of nonequilibrium electrons at semiconductor surfaces is presented. In the first part, the fundamental dynamical equations for electronic occupations and polarisations are derived using density matrix formalism (DMT) for a surface-bulk system including the interaction of electrons with the optical field and electron-phonon interactions. The matrix elements entering these equations are either determined empirically or by density functional theory (DFT) calculations. In the subsequent parts of the paper, the dynamics at two specific semiconductor surfaces are discussed in detail. The electron relaxation dynamics underlying a time-resolved two photon photoemission experiment at an InP surface is investigated in the limit of a parabolic four band model. Moreover, the electron relaxation dynamics at a Si(100) surface is analysed. Here, the coupling parameters and the band structure are obtained from an DFT calculations. (orig.)

  18. Fission excitation function for 19F + 194,196,198Pt at near and above barrier energies

    Directory of Open Access Journals (Sweden)

    Singh Varinderjit

    2015-01-01

    Full Text Available Fission excitation functions for 19F + 194,196,198Pt reactions populating 213,215,217Fr compound nuclei are reported. Out of these three compound nuclei, 213Fr is a shell closed (N=126 compound nucleus and the other two are away from the shell closure. From a comparison of the experimental fission cross-sections with the statistical model predictions, it is observed that the fission cross-sections are underestimated by the statistical model predictions using shell corrected finite range rotating liquid drop model (FRLDM fission barriers. Further the FRLDM fission barriers are reduced to fit the fission cross-sections over the entire measured energy range.

  19. Converging genetic and functional brain imaging evidence links neuronal excitability to working memory, psychiatric disease, and brain activity.

    Science.gov (United States)

    Heck, Angela; Fastenrath, Matthias; Ackermann, Sandra; Auschra, Bianca; Bickel, Horst; Coynel, David; Gschwind, Leo; Jessen, Frank; Kaduszkiewicz, Hanna; Maier, Wolfgang; Milnik, Annette; Pentzek, Michael; Riedel-Heller, Steffi G; Ripke, Stephan; Spalek, Klara; Sullivan, Patrick; Vogler, Christian; Wagner, Michael; Weyerer, Siegfried; Wolfsgruber, Steffen; de Quervain, Dominique J-F; Papassotiropoulos, Andreas

    2014-03-05

    Working memory, the capacity of actively maintaining task-relevant information during a cognitive task, is a heritable trait. Working memory deficits are characteristic for many psychiatric disorders. We performed genome-wide gene set enrichment analyses in multiple independent data sets of young and aged cognitively healthy subjects (n = 2,824) and in a large schizophrenia case-control sample (n = 32,143). The voltage-gated cation channel activity gene set, consisting of genes related to neuronal excitability, was robustly linked to performance in working memory-related tasks across ages and to schizophrenia. Functional brain imaging in 707 healthy participants linked this gene set also to working memory-related activity in the parietal cortex and the cerebellum. Gene set analyses may help to dissect the molecular underpinnings of cognitive dimensions, brain activity, and psychopathology.

  20. Time-dependent density functional study of the electronic excited states of polycyclic aromatic hydrocarbon radical ions

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, So; Head-Gordon, Martin P; Szczepanski, Jan; Vala, Martin

    2003-06-19

    A uniform, comprehensive theoretical interpretation of spectroscopic data is presented for 53 radical ion species of polycyclic aromatic hydrocarbons (PAHs) with the aid of (Tamm–Dancoff) time-dependent density functional theory (TDDFT). TDDFT is capable of predicting the transition energies to the low-lying excited states of PAH ions with quantitative accuracy (the standard deviation from experimental results being less than 0.3 eV) and their intensity patterns qualitatively correctly. The accuracy is hardly affected by the sizes of PAH ions (azulene through dinaphthocoronene), the types of transitions (Koopmans or satellite transitions), the types of orbi-tals involved (π* ← π, π* ← σ, or σ* ← π transitions), the types of ions (cations or anions), or other geometrical or electronic perturbations (non-planarity, sp3 carbons, or heterocyclic or non-benzenoid rings).

  1. Excitation functions of alpha particle induced reactions on natTi up to 40 MeV

    Science.gov (United States)

    Uddin, M. S.; Scholten, B.

    2016-08-01

    Excitation functions of the reactions natTi(α,x)48Cr, natTi(α,x)48V and natTi(α,x)46,48Sc were determined by the stacked-foil activation technique up to 40 MeV. The radioactivities produced in the natTi target were measured by γ-ray spectrometry using HPGe detector. The reaction natTi(α,x)51Cr was used to determine the beam parameters. New experimental values for the above reactions have been obtained. An intercomparison of our data with the available literature values has been done. The cross section results obtained in this work could be useful in defining new monitor reactions, radiation safety and isotope production.

  2. Comparative assessment of density functional methods for evaluating essential parameters to simulate SERS spectra within the excited state energy gradient approximation

    Science.gov (United States)

    Mohammadpour, Mozhdeh; Jamshidi, Zahra

    2016-05-01

    The prospect of challenges in reproducing and interpretation of resonance Raman properties of molecules interacting with metal clusters has prompted the present research initiative. Resonance Raman spectra based on the time-dependent gradient approximation are examined in the framework of density functional theory using different methods for representing the exchange-correlation functional. In this work the performance of different XC functionals in the prediction of ground state properties, excitation state energies, and gradients are compared and discussed. Resonance Raman properties based on time-dependent gradient approximation for the strongly low-lying charge transfer states are calculated and compared for different methods. We draw the following conclusions: (1) for calculating the binding energy and ground state geometry, dispersion-corrected functionals give the best performance in comparison to ab initio calculations, (2) GGA and meta GGA functionals give good accuracy in calculating vibrational frequencies, (3) excited state energies determined by hybrid and range-separated hybrid functionals are in good agreement with EOM-CCSD calculations, and (4) in calculating resonance Raman properties GGA functionals give good and reasonable performance in comparison to the experiment; however, calculating the excited state gradient by using the hybrid functional on the hessian of GGA improves the results of the hybrid functional significantly. Finally, we conclude that the agreement of charge-transfer surface enhanced resonance Raman spectra with experiment is improved significantly by using the excited state gradient approximation.

  3. Investigations of the potential functions of weakly bound diatomic molecules and laser-assisted excitive Penning ionization

    Energy Technology Data Exchange (ETDEWEB)

    Goble, J.H. Jr.

    1982-05-01

    Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.

  4. Gaussian density-functional study for small neutral (Al n ), positive (Al{/n +}) and negative (Al{/n -}) aluminium clusters ( n=2 5)

    Science.gov (United States)

    Calaminici, Patrizia; Russo, Nino; Toscano, Marirosa

    1995-12-01

    The structures and properties of Al n , Al{/n +}, Al{/n -} ( n=1,5) clusters have been investigated by using the Linear Combination of Gaussian Type Orbitals (LCGTO) method, considering Local (LSD) and Non Local (NLSD) Spin Density Approximations and employing a Model Core Potential (MCP) that allows the explicit treatment of 3 s 2 3 p 1 valence electrons. For each system different geometrical structures and electronic states have been considered. For Al3, Al{3/+}, Al{3/-} the most stable geometry proved to be the equilateral triangle ( D 3 h ). Al4 and Al{4/+} prefer the rhombus ( D 2 h ) structure, while the corresponding anion prefers the square ( D 4 h ) one. The trapezoidal form ( C 2 v ) is the most stable isomer for Al5, Al{5/+} and Al{5/-} clusters. The analysis of vibrational frequencies shows that these structures are minima in the potential energy surface. The binding energies ( D e), the adiabatic ionization potentials (IP) and electron affinities (EA), the chemical potentials or absolute hardnesses (η) and electronegativities (χ) have been computed. Results are in good agreement with the available experimental data and the previous high level theoretical computations.

  5. Measures of bulbar and spinal motor function, muscle innervation, and mitochondrial function in ALS rats.

    Science.gov (United States)

    Smittkamp, Susan E; Spalding, Heather N; Brown, Jordan W; Gupte, Anisha A; Chen, Jie; Nishimune, Hiroshi; Geiger, Paige C; Stanford, John A

    2010-07-29

    Symptom onset in amyotrophic lateral sclerosis (ALS) may occur in the muscles of the limbs (spinal onset) or those of the head and neck (bulbar onset). Most preclinical studies have focused on spinal symptoms, despite the prevalence of and increased morbidity and mortality associated with bulbar disease. We measured lick rhythm and tongue force to evaluate bulbar disease in the SOD1-G93A rat model of familial ALS. Body weight and grip strength were measured concomitantly. Testing spanned the early (maturation), middle (pre-symptomatic), and late (symptomatic and end-stage) phases of the disease. We measured a persistent tongue motility deficit that became apparent in the early phase of the disease, providing behavioral evidence of bulbar pathology. At end-stage, however, cytochrome oxidase (CO) activity was normal in the hypoglossal nucleus, and in the tongue, neuromuscular innervation, citrate synthase (CS) protein levels and activity, and uncoupling protein 3 (UCP3) protein levels remained unchanged. Interestingly, significant denervation and atrophy were evident in the end-stage sternomastoid muscle, providing peripheral anatomical evidence of bulbar pathology. Changes in body weight and grip strength occurred in the late phase of the disease. Extensive atrophy and denervation were observed in the end-stage gastrocnemius muscle. In contrast to our findings in the tongue, CS protein levels were decreased in the extensor digitorum longus (EDL) and soleus, although CS activity was maintained or increased. UCP3 protein was decreased also in the EDL. These data provide evidence of differential effects in muscles that were more or less affected by disease.

  6. Energy displacement function as a signature for octupole deformation in excited states

    CERN Document Server

    Raduta, A A; Ursu, I I

    2003-01-01

    Energies for three positive and three negative parity bands predicted by the extended coherent states model (ECSM) in sup 2 sup 2 sup 6 Ra are calculated and used to point out new signatures for octupole deformation in ground as well as in beta and gamma bands. A beat pattern is found by using a new displacement energy function which is more appropriate for a spectrum which exhibits large deviation from a linear J(J+1) dependence. The stability against octupole deformation is revisited from a new point of view. (authors)

  7. Preparation of Al/Si functionally graded materials using ultrasonic separation method

    Directory of Open Access Journals (Sweden)

    Zhang Zhongtao

    2008-08-01

    Full Text Available Functionally graded materials (FGM have been widely used in many industries such as aerospace, energy and electronics. In this experimental study of fabricating FGM, an approach was developed to prepare Al/Si FGM using power ultrasonic separation method. Material sample with continuously changing composition and performance/properties was successfully produced. Results showed that the microstructure of the FGM sample transited, from its top to bottom, from the hypereutectic structure with a large quantity of primary Si gradually to the eutectic, and fi nally to the hypoeutectic with numerous primary Al dendrites. The distribution of primary Si and microhardness of the FGM sample also presented graded characteristics, resulting that the wear resistance of the FGM sample decreased from top to bottom. Preliminary discussion was made on the mechanism of the formation of Al/Si FGM.

  8. Dual functions of TiC nanoparticles on tribological performance of Al/graphite composites

    Science.gov (United States)

    Fallahdoost, Hamid; Nouri, Alireza; Azimi, Amin

    2016-06-01

    In this study, the effect of TiC nanoparticles as a reinforcement on the mechanical and tribological properties of Aluminum-based self lubricating composite was investigated. The microstructure, relative density, hardness, and tribological properties of Al/graphite and Al/TiC/graphite composites were examined as a function of graphite content. The tribo-surfaces of the samples were analyzed using SEM and EDS elemental mapping. The results indicated that the addition of TiC nanoparticles not only decreased the wear rate and coefficient of friction of the composites, but also facilitated the formation of a stable graphite layer at longer sliding distances and high sliding velocities by forming a durable graphite/TiC composite on the tribo-surface. Therefore, the stability of graphite layer can be considered as a possible cause for decrease in wear rate of the Al/TiC/graphite composite.

  9. Dual effect of local anesthetics on the function of excitable rod outer segment disk membrane

    Energy Technology Data Exchange (ETDEWEB)

    Mashimo, T.; Abe, K.; Yoshiya, I.

    1986-04-01

    The effects of local anesthetics and a divalent cation, Ca2+, on the function of rhodopsin were estimated from the measurements of light-induced proton uptake. The light-induced proton uptake by rhodopsin in the rod outer segment disk membrane was enhanced at lower pH (4) but depressed at higher pHs (6 to 8) by the tertiary amine local anesthetics lidocaine, bupivacaine, tetracaine, and dibucaine. The order of local anesthetic-induced depression of the proton uptake followed that of their clinical anesthetic potencies. The depression of the proton uptake versus the concentration of the uncharged form of local anesthetic nearly describes the same curve for small and large dose of added anesthetic. Furthermore, a neutral local anesthetic, benzocaine, depressed the proton uptake at all pHs between 4 and 7. These results indicate that the depression of the proton uptake is due to the effect of only the uncharged form. It is hypothesized that the uncharged form of local anesthetics interacts hydrophobically with the rhodopsin in the disk membrane. The dual effect of local anesthetics on the proton uptake, on the other hand, suggests that the activation of the function of rhodopsin may be caused by the charged form. There was no significant change in the light-induced proton uptake by rhodopsin when 1 mM of Ca2+ was introduced into the disk membrane at varying pHs in the absence or presence of local anesthetics. This fact indicates that Ca2+ ion does not influence the diprotonating process of metarhodopsin; neither does it interfere with the local anesthetic-induced changes in the rhodopsin molecule.

  10. Assessment of the Global and Regional Land Hydrosphere and Its Impact on the Balance of the Geophysical Excitation Function of Polar Motion

    Directory of Open Access Journals (Sweden)

    Wińska Małgorzata

    2016-02-01

    Full Text Available The impact of continental hydrological loading from land water, snow and ice on polar motion excitation, calculated as hydrological angular momentum (HAM, is difficult to estimate, and not as much is known about it as about atmospheric angular momentum (AAM and oceanic angular momentum (OAM. In this paper, regional hydrological excitations to polar motion are investigated using monthly terrestrial water storage data derived from the Gravity Recovery and Climate Experiment (GRACE mission and from the five models of land hydrology. The results show that the areas where the variance shows large variability are similar for the different models of land hydrology and for the GRACE data. Areas which have a small amplitude on the maps make an important contribution to the global hydrological excitation function of polar motion. The comparison of geodetic residuals and global hydrological excitation functions of polar motion shows that none of the hydrological excitation has enough energy to significantly improve the agreement between the observed geodetic excitation and geophysical ones.

  11. New Approaches to Exciting Exergame-Experiences for People with Motor Function Impairments

    Directory of Open Access Journals (Sweden)

    Martina Eckert

    2017-02-01

    Full Text Available The work presented here suggests new ways to tackle exergames for physical rehabilitation and to improve the players’ immersion and involvement. The primary (but not exclusive purpose is to increase the motivation of children and adolescents with severe physical impairments, for doing their required exercises while playing. The proposed gaming environment is based on the Kinect sensor and the Blender Game Engine. A middleware has been implemented that efficiently transmits the data from the sensor to the game. Inside the game, different newly proposed mechanisms have been developed to distinguish pure exercise-gestures from other movements used to control the game (e.g., opening a menu. The main contribution is the amplification of weak movements, which allows the physically impaired to have similar gaming experiences as the average population. To test the feasibility of the proposed methods, four mini-games were implemented and tested by a group of 11 volunteers with different disabilities, most of them bound to a wheelchair. Their performance has also been compared to that of a healthy control group. Results are generally positive and motivating, although there is much to do to improve the functionalities. There is a major demand for applications that help to include disabled people in society and to improve their life conditions. This work will contribute towards providing them with more fun during exercise.

  12. New Approaches to Exciting Exergame-Experiences for People with Motor Function Impairments

    Science.gov (United States)

    Eckert, Martina; Gómez-Martinho, Ignacio; Meneses, Juan; Martínez, José-Fernán

    2017-01-01

    The work presented here suggests new ways to tackle exergames for physical rehabilitation and to improve the players’ immersion and involvement. The primary (but not exclusive) purpose is to increase the motivation of children and adolescents with severe physical impairments, for doing their required exercises while playing. The proposed gaming environment is based on the Kinect sensor and the Blender Game Engine. A middleware has been implemented that efficiently transmits the data from the sensor to the game. Inside the game, different newly proposed mechanisms have been developed to distinguish pure exercise-gestures from other movements used to control the game (e.g., opening a menu). The main contribution is the amplification of weak movements, which allows the physically impaired to have similar gaming experiences as the average population. To test the feasibility of the proposed methods, four mini-games were implemented and tested by a group of 11 volunteers with different disabilities, most of them bound to a wheelchair. Their performance has also been compared to that of a healthy control group. Results are generally positive and motivating, although there is much to do to improve the functionalities. There is a major demand for applications that help to include disabled people in society and to improve their life conditions. This work will contribute towards providing them with more fun during exercise. PMID:28208682

  13. Optical properties of Al nanostructures from time dependent density functional theory

    KAUST Repository

    Mokkath, Junais Habeeb

    2016-04-05

    The optical properties of Al nanostructures are investigated by means of time dependent density functional theory, considering chains of varying length and ladders/stripes of varying aspect ratio. The absorption spectra show redshifting for increasing length and aspect ratio. For the chains the absorption is dominated by HOMO → LUMO transitions, whereas ladders and stripes reveal more complex spectra of plasmonic nature above a specific aspect ratio.

  14. Fabrication of Al/Diamond Particles Functionally Graded Materials by Centrifugal Sintered-Casting Method

    Science.gov (United States)

    Watanabe, Yoshimi; Shibuya, Masafumi; Sato, Hisashi

    2013-03-01

    The continuous graded structure of functionally graded materials (FGMs) can be created under a centrifugal force. Centrifugal sintered-casting (CSC) method, proposed by the authors, is one of the fabrication methods of FGM under centrifugal force. This method is a combination of the centrifugal sintering method and centrifugal casting method. In this study, Al/diamond particle FGM was fabricated by the proposed method.

  15. Functionalization of AlGaN/GaN heterostructures with TFAAD

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Stefan Udo [Institute of Microsystem Technology (IMTEK), University of Freiburg, Georges-Koehler-Allee 106, 79110 Freiburg (Germany); Cimalla, Volker; Nebel, Christoph; Ambacher, Oliver [Fraunhofer Institute for Applied Solid State Physics, Tullastrasse 72, 79108 Freiburg (Germany)

    2010-07-01

    AlGaN/GaN high electron mobility transistors (HEMTs) show great promise for the realization of sensors for biomolecular, pharmaceutical and medical purposes. The high sensitivity and the stability in biological solutions are great advantages of this principle. The transduction is based on the AlGaN/GaN heterostructure. Charges on its surface influence the electron density in the 2-dimensional electron gas (2DEG) near the interface of the heterostructure. For a specific sensor, biological recognition methods shall be used. Therefore biomolecules need to be covalently linked to the semiconductor. The surface must be functionalized with a single layer of molecules that form covalent bonds to the surface and present functional groups for the connection with the biomolecule. In this work we investigate the functionalization of AlGaN/GaN heterostructures with 10-Trifluoroacetamiddec-1-ene (TFAAD), a molecule that can bond to GaN in a photochemical reaction and has a protected Amino group for the further procedure. The focus is on the influence of the illumination spectrum and surface pretreatments on the reaction kinetics and the resulting layer morphology with respect to the designated application.

  16. Implications of cortical balanced excitation and inhibition, functional heterogeneity, and sparseness of neuronal activity in fMRI

    Science.gov (United States)

    Xu, Jiansong

    2015-01-01

    Blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) studies often report inconsistent findings, probably due to brain properties such as balanced excitation and inhibition and functional heterogeneity. These properties indicate that different neurons in the same voxels may show variable activities including concurrent activation and deactivation, that the relationships between BOLD signal and neural activity (i.e., neurovascular coupling) are complex, and that increased BOLD signal may reflect reduced deactivation, increased activation, or both. The traditional general-linear-model-based-analysis (GLM-BA) is a univariate approach, cannot separate different components of BOLD signal mixtures from the same voxels, and may contribute to inconsistent findings of fMRI. Spatial independent component analysis (sICA) is a multivariate approach, can separate the BOLD signal mixture from each voxel into different source signals and measure each separately, and thus may reconcile previous conflicting findings generated by GLM-BA. We propose that methods capable of separating mixed signals such as sICA should be regularly used for more accurately and completely extracting information embedded in fMRI datasets. PMID:26341939

  17. Calculation of excitation functions of proton, alpha and deuteron induced reactions for production of medical radioisotopes {sup 122–125}I

    Energy Technology Data Exchange (ETDEWEB)

    Artun, Ozan, E-mail: ozanartun@yahoo.com; Aytekin, Hüseyin, E-mail: huseyinaytekin@gmail.com

    2015-02-15

    In this work, the excitation functions for production of medical radioisotopes {sup 122–125}I with proton, alpha, and deuteron induced reactions were calculated by two different level density models. For the nuclear model calculations, the Talys 1.6 code were used, which is the latest version of Talys code series. Calculations of excitation functions for production of the {sup 122–125}I isotopes were carried out by using the generalized superfluid model (GSM) and Fermi-gas model (FGM). The results have shown that generalized superfluid model is more successful than Fermi-gas model in explaining the experimental results.

  18. Is the existence of a softest point in the directed flow excitation function an unambiguous signal for the creation of a quark-gluon plasma?

    CERN Document Server

    Bleicher, M; Bleicher, Marcus

    2005-01-01

    The excitation function of the in-plane directed flow of nucleons is studied within a non-equilibrium transport approach. It is demonstrated that a local minimum in the excitation function of the directed flow develops, which is not related to a transition into a quark-gluon plasma (QGP) phase. It is a consequence of the dynamical softening of the underlying equation of state, due to the onset of resonance matter and particle production. Thus, the interpretation of this minimum as a 'smoking gun' signature for the creation of a QGP is premature.

  19. Functions of FUS/TLS From DNA Repair to Stress Response: Implications for ALS

    Directory of Open Access Journals (Sweden)

    Reddy Ranjith Kumar Sama

    2014-08-01

    Full Text Available Fused in sarcoma/translocated in liposarcoma (FUS/TLS or FUS is a multifunctional DNA-/RNA-binding protein that is involved in a variety of cellular functions including transcription, protein translation, RNA splicing, and transport. FUS was initially identified as a fusion oncoprotein, and thus, the early literature focused on the role of FUS in cancer. With the recent discoveries revealing the role of FUS in neurodegenerative diseases, namely amyotrophic lateral sclerosis and frontotemporal lobar degeneration, there has been a renewed interest in elucidating the normal functions of FUS. It is not clear which, if any, endogenous functions of FUS are involved in disease pathogenesis. Here, we review what is currently known regarding the normal functions of FUS with an emphasis on DNA damage repair, RNA processing, and cellular stress response. Further, we discuss how ALS-causing mutations can potentially alter the role of FUS in these pathways, thereby contributing to disease pathogenesis.

  20. A Guided Self-Consistent-Field Method for Excited-State Wave Function Optimization: Applications to Ligand-Field Transitions in Transition-Metal Complexes.

    Science.gov (United States)

    Peng, Bo; Van Kuiken, Benjamin E; Ding, Feizhi; Li, Xiaosong

    2013-09-10

    A guided self-consistent field (SCF) method is presented in this paper. This method uses the eigenspace update-and-following idea to improve the SCF method for optimizing wave functions that are higher-energy solutions to the Roothaan-Hall equation. In this method, the eigenvectors of the previous SCF step are used to prediagonalize the current Fock/Kohn-Sham matrix, preserving the ordering of orbital occupations. When the subject of interest is an excited state of the same spin symmetry as the ground state, the initial guess of excited wave function is improved with a preconditioning step. The preconditioning step is an SCF iteration applied to the β spin manifold if the initial guess is generated by orbital permutation in the α spin manifold. This simple preconditioning step gives rise to more-stable SCF convergence using the algorithm presented herein. The guided SCF method is used to optimize ligand-field excited states in tetrahedral transition-metal complexes, and calculate ΔSCF excitation energies. The calculated ligand-field transition energies are compared with those obtained from orbital energy differences, linear response time-dependent density functional theory, and experiments. The excitation energies obtained using the method presented in this work show a significant improvement over orbital energy differences and linear response method.

  1. C-E Translation of Internet Neologisms from the Perspective of Function-al Equivalence

    Institute of Scientific and Technical Information of China (English)

    张利梅

    2015-01-01

    With the rapid development of China's economy and society,neologisms are involved in every field and continue to boom.However,Internet neologisms have an important influence on our mind and language form and update the way of information transmission and communication as well.It rapidly steps into people's life with different style and reflect social phenomenon and special cultural connotation with its unique charm.It is necessary to be aware of Internet neologisms translation when applying them into the language system.To those foreign readers who differ from Chinese mind and culture,inappropriate translation could result in misunderstanding and further cause communication failure.Hence,English translation for Internet neologisms should be placed considerable value.This paper will employ Eugene A.Nida's functional equivalence to probe into translation methods of In-ternet neologisms in order to find out appropriate translation.

  2. Catalytic characterization of bi-functional catalysts derived from Pd–Mg–Al layered double hydroxides

    Indian Academy of Sciences (India)

    N N Das; S C Srivastava

    2002-08-01

    Hydrotalcite like precursors containing PdII–MgII–AlIII with varying molar ratios, (Pd + Mg)/Al ≈ 3 and Mg/Pd ≈ 750 to 35, were prepared by coprecipitation of metal nitrates at constant pH. Characterization of samples as synthesized and their calcined products by elemental analyses, powder XRD, TG–DTA, FT–IR spectroscopy, TPR and N2 physisorption indicated a well crystalline hydrotalcite like structure with incorporation of Pd2+ in the brucite layers. Thermal decomposition of hydrotalcite precursors at intermediate temperatures led to amorphous mixed oxides, Pd/MgAl(O), which on reduction yielded bi-functional catalyst, Pd°/MgAl(O). The resultant catalysts with acid, base and hydrogenating sites, were highly active and selective for one-step synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen. The results showed an optimal balance between acid-base and metallic sites were required to increase the selectivity of MIBK and stability of the catalysts.

  3. Cryogenic exciter

    Science.gov (United States)

    Bray, James William [Niskayuna, NY; Garces, Luis Jose [Niskayuna, NY

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  4. Dielectric function and critical points of AlP determined by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, S.Y.; Kim, T.J.; Jung, Y.W.; Barange, N.S.; Park, H.G.; Kim, J.Y.; Kang, Y.R. [Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Kim, Y.D., E-mail: ydkim@khu.ac.kr [Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701 (Korea, Republic of); Shin, S.H.; Song, J.D. [Center for Opto-Electronic Convergence Systems, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Liang, C.-T.; Chang, Y.-C. [Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan (China)

    2014-02-25

    Highlights: • We report the dielectric function ε of AlP from 0.74 to 6.54 eV. • The critical points (CPs) in the E{sub 2} spectral range are important for band-structure analysis. • We extract ε of AlP, using the multilayer parametric model. • The CP energies are obtained from numerically calculated second-energy-derivatives. • We identify these CPs from the linear augmented Slater-type orbital method. -- Abstract: We report the room-temperature dielectric function ε of AlP from 0.74 to 6.54 eV obtained by in situ spectroscopic ellipsometry. Measurements were done on a 1.2 μm thick film grown on (0 0 1) GaAs by molecular beam epitaxy, with ε extracted using a multilayer parametric model. Critical point energies of features in the ε spectra were obtained from numerically calculated second-energy-derivatives, and their Brillouin-zone origins identified by band-structure calculations done using the linear augmented Slater-type orbital method.

  5. Sexual excitement.

    Science.gov (United States)

    Stoller, R J

    1976-08-01

    Sexual excitement depends on a scenario the person to be aroused has been writing since childhood. The story is an adventure, an autobiography disguised as fiction, in which the hero/heroine hides crucial intrapsychic conflicts, mysteries, screen memories of actual traumatic events and the resolution of these elements into a happy ending, best celebrated by orgasm. The function of the fantasy is to take these painful experiences and convert them to pleasure-triumph. In order to sharpen excitement-the vibration between the fear of original traumas repeating and the hope of a pleasurable conclusion this time-one introduces into the story elements of risk (approximations of the trauma) meant to prevent boredom and safety factors (sub-limnal signals to the storyteller that the risk are not truly dangerous). Sexual fantasy can be studied by means of a person's daydreams (including those chosen in magazines, books, plays, television, movies, and outright pornography), masturbatory behavior, object choice, foreplay, techniques of intercourse, or postcoital behavior.

  6. Preparation of Al/Si functionally graded materials using ultrasonic separation method

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhongtao; LI Tingju; Yue Hongyun; Zhang Jian; Li Jie

    2008-01-01

    Functionally graded materials (FGM) have been widely used in many industries such as aerospace, energy and electronics. In this experimental study of fabricating FGM, an approach was developed to prepare Al/Si FGM using power ultrasonic separation method. Material sample with continuously changing composition and performance/properties was successfully produced. Results showed that the microstructure of the FGM sample transited, from its top to bottom, from the hypereutectic structure with a large quantity of primary Si gradually to the eutectic, and finally to the hypoeutectic with numerous primary AI dendrites. The distribution of primary Si and microhardness of the FGM sample also presented graded characteristics, resulting that the wear resistance of the FGM sample decreased from top to bottom. Preliminary discussion was made on the mechanism of the formation of Al/Si FGM.

  7. Direct Metal Deposition of Functional Graded Structures in Ti- Al System

    Science.gov (United States)

    Shishkovsky, I.; Missemer, F.; Smurov, I.

    A direct laser metal deposition (DLMD) technology with co-axial powder injection is used to fabricate a complex functional graded structure (FGS) fabrication. The aim of the study is to demonstrate the possibility to produce intermetallic phases in the Ti-Al powder systems in the course of a single-step DMD process. Besides, relationships between the main laser cladding parameters and the intermetallic phase structures of the built-up objects have been studied. In our research we applied the optical microscopy, X-ray analysis, microhardness measurement and SEM with EDX analysis of the laser-fabricated intermetallics. The discussion of the mechanisms of Ti x Al y (x,y = 1.3) intermetallic transformations in exothermal reactions is also offered in the report.

  8. Excitation function shape and neutron spectrum of the 7Li(p ,n )7Be reaction near threshold

    Science.gov (United States)

    Martín-Hernández, Guido; Mastinu, Pierfrancesco; Maggiore, Mario; Pranovi, Lorenzo; Prete, Gianfranco; Praena, Javier; Capote-Noy, Roberto; Gramegna, Fabiana; Lombardi, Augusto; Maran, Luca; Scian, Carlo; Munaron, Enrico

    2016-09-01

    The forward-emitted low energy tail of the neutron spectrum generated by the 7Li(p ,n )7Be reaction on a thick target at a proton energy of 1893.6 keV was measured by time-of-flight spectroscopy. The measurement was performed at BELINA (Beam Line for Nuclear Astrophysics) of the Laboratori Nazionali di Legnaro. Using the reaction kinematics and the proton on lithium stopping power the shape of the excitation function is calculated from the measured neutron spectrum. Good agreement with two reported measurements was found. Our data, along with the previous measurements, are well reproduced by the Breit-Wigner single-resonance formula for s -wave particles. The differential yield of the reaction is calculated and the widely used neutron spectrum at a proton energy of 1912 keV was reproduced. Possible causes regarding part of the 6.5% discrepancy between the 197Au(n ,γ ) cross section measured at this energy by Ratynski and Kappeler [Phys. Rev. C 37, 595 (1988), 10.1103/PhysRevC.37.595] and the one obtained using the Evaluated Nuclear Data File version B-VII.1 are given.

  9. Investigation of the effect of inositol trisphosphate in skinned skeletal muscle fibres with functional excitation-contraction coupling.

    Science.gov (United States)

    Posterino, G S; Lamb, G D

    1998-01-01

    The effect of inositol trisphosphate (IP3) was investigated in mechanically skinned fibres which had the endogenous level of sarcoplasmic reticulum (SR) Ca2+ and in which the normal excitation-contraction (E-C) coupling mechanism was still functional. Application of 50 or 100 microM IP3 failed to induce a detectable force response in any such skinned fibre from either the extensor digitorum longus muscle of the rat or iliofibularis muscle of the toad, irrespective of whether the fibre was: (a) in its normally polarized, resting state; (b) chronically depolarized to inactivate the voltage sensors; (c) paralysed with D600; or (d) depolarized to threshold for force activation. Furthermore, the size of the response to subsequent depolarization or exposure to caffeine (2mM) or reduced myoplasmic [Mg2+] indicated that little if any Ca2+ had been lost from the SR during the period of IP3 exposure (> or = 1 min). Also, IP3 did not induce a detectable force response when SR Ca2+ uptake was potently inhibited with 20 microM TBQ. Exposure to IP3 (50 microM) slightly potentiated the peak force response to depolarization in toad fibres, and this was probably because of an accompanying small increase in Ca2+ sensitivity of the contractile apparatus. These results appear inconsistent with the proposal that IP3 acts as the second messenger in E-C coupling in skeletal muscle.

  10. Excitation functions of deuteron-induced nuclear reactions on natural platinum up to 24 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Khandaker, Mayeen Uddin, E-mail: mu_khandaker@yahoo.com [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Haba, Hiromitsu; Murakami, Masashi [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Otuka, Naohiko [Nuclear Data Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, A-1400 Vienna (Austria); Kassim, Hasan Abu [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-11-01

    Excitation functions of the {sup nat}Pt(d,x){sup 192,193,194,195,196m2,196,198m,198,199}Au, {sup 195m,197}Pt and {sup 190(g+m1+0.086m2),192(g+m1),194m}Ir nuclear reactions were measured from the respective threshold up to 24 MeV deuteron energy by using the stacked foil activation technique combined with HPGe gamma-ray spectrometry. Measured data were critically compared with the available literature data and theoretical data extracted from the TENDL-2013 library, and only partial agreement among them was found. Physical thick target yields for the investigated reaction products were also deduced and compared with the directly measured ones in the literature. The deduced yield curves indicate that a low energy cyclotron (<15 MeV) and a highly enriched {sup 198}Pt target could be used to obtain {sup 198,199}Au in no carrier added form. All cross-sections for {sup 190(g+m1+0.086m2),194m}Ir and those for {sup 193,194,196m2,196,199}Au, and {sup 195m,197}Pt in the lower energy region are reported for the first time.

  11. Excitation functions of {sup nat}Zr + p nuclear processes up to 70 MeV: New measurements and compilation

    Energy Technology Data Exchange (ETDEWEB)

    Szelecsényi, F., E-mail: szele@atomki.hu [Cyclotron Application Department, Institute for Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/c, Debrecen H-4026 (Hungary); Steyn, G.F. [iThemba Laboratory for Accelerator Based Sciences, Faure, P.O. Box 722, Somerset West 7129 (South Africa); Kovács, Z. [Cyclotron Application Department, Institute for Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/c, Debrecen H-4026 (Hungary); Vermeulen, C. [Centre for Radiopharmaceutical Sciences, Paul Scherrer Institute, 5232 Villigen-PSI (Switzerland); Nagatsu, K.; Zhang, M.-R.; Suzuki, K. [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku-Chiba, 263-8555 (Japan)

    2015-01-15

    Excitation functions for the formation of various radionuclides of Nb, Zr, Y and Sr in proton-induced reactions on natural zirconium were measured up to 66 MeV using the stacked-foil technique. New data are presented for {sup 89m,89g}Nb, {sup 90(m+g)}Nb, {sup 91m}Nb, {sup 92m}Nb, {sup 95m,95g}Nb, {sup 96}Nb, {sup 86}Zr, {sup 87(m+g)}Zr, {sup 88}Zr, {sup 89(0.94m+g)}Zr, {sup 95}Zr, {sup 85m,85g}Y, {sup 86m,86(0.99m+g)}Y, {sup 87m,87(0.984m+g)}Y, {sup 88}Y, {sup 90m}Y, {sup 91m}Y and {sup 85(0.87m+g)}Sr. The experimental results are compared with the available literature data as well as the evaluated theoretical predictions by means of the TALYS code, up to 70 MeV, as compiled in the TENDL-2013 library. For a number of short-lived radionuclides, i.e., {sup 85m}Y, {sup 85g}Y, {sup 86m}Y, {sup 90m}Y, {sup 91m}Y and {sup 87(m+g)}Zr, the present experimental cross sections are likely the first to be reported for their formation in {sup nat}Zr + p.

  12. Optical and magnetic excitations of metal-encapsulating Si cages: A systematic study by time-dependent density functional theory

    CERN Document Server

    Oliveira, Micael J T; Sousa, José R F; Nogueira, Fernando; Gueorguiev, Gueorgui K

    2013-01-01

    Systematic study of the optical and magnetic excitations of twelve MSi$_{12}$ and four MSi$_{10}$ transition metal encapsulating Si cages has been carried out by employing real time time-dependent density functional theory. Criteria for the choice of transition metals (M) are clusters' stability, synthesizability, and diversity. It was found that both the optical absorption and the spin-susceptibility spectra are mainly determined by, in decreasing order of importance: 1) the cage shape, 2) the group in the Periodic Table M belongs to, and 3) the period of M in the Periodic Table. Cages with similar structures and metal species that are close to each other in the Periodic Table possess spectra sharing many similarities, e. g., the optical absorption spectra of the MSi$_{12}$ (M = V, Nb, Ta, Cr, Mo, and W), which are highly symmetric and belong to groups 4 and 5 of the Periodic Table, all share a very distinctive peak at around 4 eV. In all cases, although some of the observed transitions are located at the Si...

  13. Excitation functions for the formation of some short-lived products in proton-induced reactions on silver

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M.S.; Latif, S.K.A. [Inst. of Nuclear Science and Technology, Atomic Energy Research Establishment, Savar, Dhaka (Bangladesh); Baba, M.; Hagiwara, M. [Cyclotron and Radioisotope Center, Tohoku Univ., Sendai (Japan); Qaim, S.M. [Inst. fuer Nuklearchemie, Forschungszentrum Juelich GmbH, Juelich (Germany)

    2008-07-01

    Excitation functions of the {sup nat}Ag(p, xn){sup 104,} {sup 105}Cd and {sup nat}Ag(p, pxn){sup 103,} {sup 104m,g,} {sup 104g}Ag reactions were measured for the first time over the proton energy range of 32 to about 60 MeV. The data were compared with the results of precompound-hybrid model calculations, whereby only partial agreement was obtained. The contribution of the {sup 103}Ag precursor decay to the total formation of the therapeutic radionuclide {sup 103}Pd in proton activation of silver was estimated: it amounted to about 70%. The various possible routes for the production of {sup 103}Pd were also considered: the {sup nat}Ag(p, x){sup 103}Pd and {sup 103}Rh(p, n){sup 103}Pd processes were found to be most interesting. Despite its somewhat lower yield, the latter process is preferred because it can be applied at a low-energy cyclotron. (orig.)

  14. Excitation functions of (d,x) nuclear reactions on natural titanium up to 24 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Khandaker, Mayeen Uddin, E-mail: mu_khandaker@yahoo.com [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Haba, Hiromitsu; Kanaya, Jumpei [Nishina Center for Accelerator-based Science, RIKEN, Wako, Saitama 351-0198 (Japan); Otuka, Naohiko [Nuclear Data Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, A-1400 Vienna (Austria)

    2013-02-01

    Excitation functions of the {sup nat}Ti(d,x){sup 48}V and {sup nat}Ti(d,x){sup 43,44m,44g,46,47,48}Sc nuclear reactions were measured up to a 24-MeV deuteron energy by using a stacked-foil activation technique combined with γ-ray spectrometry with a high-purity germanium detector at the AVF cyclotron of the RIKEN RI Beam Factory, Wako, Japan. An overall good agreement is found between the measured cross-sections and the literature ones, whereas partial agreements are obtained for the theoretical calculations based on the TALYS code. Physical thick target yields, i.e., induced radioactivities per unit fluence of the 24-MeV deuteron were also deduced, and they were compared with the directly measured ones in the literature. The present results will have an important role in enrichment of the literature database of the deuteron-induced reactions on natural titanium leading to various applications.

  15. The 181Ta(7Li,5n)183Os reaction: Measurement and analysis of the excitation function and isomeric cross-section ratios

    Science.gov (United States)

    Ismail, M.; Sharma, R. P.; Rashid, M. H.

    1998-03-01

    Excitation function and isomeric cross-section ratios for the production of 183Osm,g by 7Li-induced reactions on 181Ta are obtained from the measurements of the residual activities by the conventional stacked-foils technique from threshold to 50 MeV. The excitation function and isomeric cross-section ratios for nuclear reaction 181Ta(7Li,5n)183Osm,g are compared with the theoretical statistical model calculation by using the ALICE/91, STAPRE, and CASCADE codes. In the energy range of the present measurement the excitation functions are fitted fairly well by both the geometry dependent hybrid (GDH) model and the hybrid model of Blann with initial exciton number n0=7 (nn=4, np=3, nh=0) using the ALICE/91 code. The experimental isomeric cross-section ratios are also reproduced fairly well by the calculation using the STAPRE code. However, the CASCADE code calculations slightly underpredict the cross section but reproduce the shape. In general, the statistical model under a suitable set of global assumptions, can reproduce the excitation function as well as isomeric cross-section ratios.

  16. Assessment of Charge-Transfer Excitations in Organic Dyes obtained from TD-srDFT Based on Long-Range MP2 and MCSCF Wave Functions

    CERN Document Server

    Hedegård, Erik D; Knecht, Stefan; Fromager, Emmanuel; Jensen, Hans Jørgen Aa

    2013-01-01

    Charge transfer excitations can be described within TD-DFT, not only by means of long-range corrected exchange functionals but also with a combination of wave function theory and TD-DFT based on range separation. The latter approach enables a rigorous formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range MCSCF and SOPPA ans\\"atze with a short-range DFT (srDFT) description. We find that the combinations of SOPPA or MCSCF with TD-DFT yield better results than could be expected from the pure wave function schemes. For the Time-Dependent MCSCF short-range DFT ansatz (TD-MC-srDFT) excitation energies calculated over a larger benchmark set of molecules with predominantly single reference character yield good agreement with their reference values, and are in general comparable to the long-range corrected functional CAM-B3LYP. The...

  17. Towards bridging the gap between acid-base transporters and neuronal excitability modulation.

    Science.gov (United States)

    Liu, Ying; Chen, Li-Ming

    2014-01-01

    pH homeostasis is a fundamental regulator of the function of the central nervous system. Dysfunction of acid-base transporters often results in disturbance of neuronal excitability. In a latest issue of Journal of Neuroscience, Jones et al. report that increasing intracellular bicarbonate concentration substantially stimulates the excitability of pyramidal neurons from mouse hippocampus by inhibiting KCNQ potassium channel. The finding shed important new light in understanding the molecular mechanism underlying the regulation of neuronal excitability by acid-base transporters.

  18. Transition moments between excited electronic states from the Hermitian formulation of the coupled cluster quadratic response function

    CERN Document Server

    Tucholska, Aleksandra; Moszynski, Robert

    2016-01-01

    We introduce a new method for the computation of the transition moments between the excited electronic states based on the expectation value formalism of the coupled cluster theory [B. Jeziorski and R. Moszynski, Int. J. Quant. Chem. 48, 161 (1993)]. The working expressions of the new method solely employ the coupled cluster amplitudes. In the approximation adopted in the present paper the cluster expansion is limited to single, double, and linear triple excitations. The computed dipole transition probabilities for the singlet-singlet and triplet-triplet transitions in alkali earth atoms agree well with the available theoretical and experimental data. In contrast to the existing coupled cluster response theory, the matrix elements obtained by using our approach satisfy the Hermitian symmetry even if the excitations in the cluster operator are truncated. As a part of the numerical evidence for the new method, we report calculations of the transition moments between the excited triplet states which have not yet...

  19. Atomic, Molecular, and Optical Physics: Optical Excitation Function of H(1s-2p) Produced by electron Impact from Threshold to 1.8 keV

    Science.gov (United States)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Bray, I.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1997-01-01

    The optical excitation function of prompt Lyman-Alpha radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet mono- chromator system was used to measure the emitted Lyman-Alpha radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Statistical and known systematic uncertainties in our data range from +/- 4% near threshold to +/- 2% at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close- coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10% level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7% of the CCC calculations over the 14 eV-1.8 keV range. The present CCC calculations converge on the Bethe- Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3% is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV - 1.8 keV energy range.

  20. Investigation of Preheat Temprature Effect on the Sturcture of Functionally Graded Ni3Al/NiAl/NiTi Intermetallic Compound

    Directory of Open Access Journals (Sweden)

    Musa Kılıç

    2015-12-01

    Full Text Available In this study, a functional graded material (FGM consisted of NiTi NiAl and Ni3Al were manufactured by self-propagating high-temperature synthesis (SHS technique. These three different compound powders were mixed in a rotating container after accurately weighed and cold compacted under 200 MPa pressure. These pressed samples were produced for 200, 300 and 400 ° C preheating temperature by igniting with high voltage under argon gas atmosphere. The microstructures of these functional graded materials were examined by microscopy, Scanning Electron Microscopy (SEM and X-Ray Diffraction (XRD. Consequently, functional graded material successful generated by SHS in every three preheating temperature and the metallic desired compounds were obtained but, it was seen that apart from the main phases in the intersection there are other phases with more melting and gaps.

  1. Dielectric function and electro-optical properties of (Al,Ga)N/GaN-heterostructures; Dielektrische Funktion und elektrooptische Eigenschaften von (Al,Ga)N/GaN-Heterostrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Buchheim, Carsten

    2010-04-23

    In this work extensive investigations on nitride semiconductors by optical spectroscopy are presented. The ordinary and the extraordinary component of the dielectric function of GaN in the spectral range from 1.2 to 9.8 eV is shown for the first time. It is demonstrated, that the transparent spectral range is clearly influenced by higher energetic critical points of the band structure. The optical selection rules for GaN and AlN are verified considering the actual strain state. The change of the valence band ordering of AlN in comparison to GaN is proven and the crystal field splitting is estimated for AlN. The ordinary dielectric function of AlGaN is determined for different Al contents. The data are used for developing an analytical model, which includes excitonic effects and bowings. It allows the calculation of the dielectric function for arbitrary alloy compositions. (GaN/)AlGaN/GaN heterostructures are investigated by spectroscopic ellipsometry as well as by photoreflectance and electroreflectance. The optical data yields the electric field strengths of the individual layers to determine the density of the two-dimensional carrier gases at the heterointerfaces with high accuracy. The surface potential is calculated from the combination of experiments and Schroedinger-Poisson calculations. Its dependency on the Al content is quantified. For the special case of thick cap layers the coexistence of electron and hole gases in one sample is experimentally proven for the first time. Several interband transitions between quantized states in AlN/GaN superlattices are observed by electroreflectance. The comparison to quantum mechanical calculations demonstrates the influence of strain and electrical fields (quantum confined Stark effect). For both the ratio of the thicknesses of quantum wells and barriers is crucial. From the dielectric function of the superlattices it becomes obvious, that quantum size effects are not only important for the vicinity of the bandgap, but

  2. Electronically Excited States of Vitamin B12: Benchmark Calculations Including Time-Dependent Density Functional Theory and Correlated Ab Initio Methods

    CERN Document Server

    Kornobis, Karina; Wong, Bryan M; Lodowski, Piotr; Jaworska, Maria; Andruniów, Tadeusz; Rudd, Kenneth; Kozlowski, Pawel M; 10.1021/jp110914y

    2011-01-01

    Time-dependent density functional theory (TD-DFT) and correlated ab initio methods have been applied to the electronically excited states of vitamin B12 (cyanocobalamin or CNCbl). Different experimental techniques have been used to probe the excited states of CNCbl, revealing many issues that remain poorly understood from an electronic structure point of view. Due to its efficient scaling with size, TD-DFT emerges as one of the most practical tools that can be used to predict the electronic properties of these fairly complex molecules. However, the description of excited states is strongly dependent on the type of functional used in the calculations. In the present contribution, the choice of a proper functional for vitamin B12 was evaluated in terms of its agreement with both experimental results and correlated ab initio calculations. Three different functionals, i.e. B3LYP, BP86, and LC-BLYP, were tested. In addition, the effect of relative contributions of DFT and HF to the exchange-correlation functional ...

  3. Erroneous Wave Functions of Ciuchi et al for Collective Modes in Neutron Production on Metallic Hydride Cathodes

    CERN Document Server

    Widom, A; Larsen, L

    2012-01-01

    There is a recent comment (Ciuchi et al., 2012) concerning the theory of collective many body effects on the neutron production rates in a chemical battery cathode. Ciuchi et al employ an inverse beta decay expression that contains a two body amplitude. Only one electron and one proton may exist in the Ciuchi et al model initial state wave function. A flaw in their reasoning is that one cannot in reality describe collective many body correlations with only a two particle wave function. One needs very many particles to describe collective effects. In the model wave functions of Ciuchi et al there are no metallic hydrides, there are no cathodes and there are no chemical batteries. Employing a wave function with only one electron and one proton is inadequate for describing collective metallic hydride surface quantum plasma physics in cathodes accurately.

  4. Spectrographic determination of impurities in ammonium bifluoride. III. Study of the processes of vaporization, transport and excitation of the elements Al, B, Cu and Cr; Determinacion espectrografico de impurezas en bifluoruro amonico. III. Estudio de los procesos de volatilizacion, transporte y excitacion de los elementos Al, B, Cu, Cr

    Energy Technology Data Exchange (ETDEWEB)

    Alduan, F. A.; Roca, M.; Capdevila, C.

    1979-07-01

    The influences of the processes of vaporization, transport and excitation on the shape of the volatilization-excitation curves and on the values of the spectral-line intensities have been investigated in a method for the spectrographic determination of Al, B, Cu and Cr In ammonium bifluoride samples by direct current are excitation in Scribner type electrodes, with addition of different matrices (graphite, 63203, GeO{sub 2}, MgO and Zn0). The reaction products in the electrode cavity have been identified by X-ray powder diffraction analysis and the percentages of vaporized and diffused element evaluated through analysis by total-burning spectrographic methods. In addition, the values of both the number of particles entering the discharge column and the transport efficiencies have been calculated. Thus, the origin of most observed differences has been explained. (Author) 11 refs.

  5. Time-dependent density functional theory study on the excited-state hydrogen-bonding characteristics of polyaniline in aqueous environment

    Science.gov (United States)

    Zhang, Yahong; Duan, Yuping; Liu, Jin

    2017-01-01

    A theoretical study was carried out to study the excited-state of hydrogen-bonding characteristics of polyaniline (PANI) in aqueous environment. The hydrogen-bonded PANI-H2O complexes were studied using first-principles calculations based on density functional theory (DFT). The electronic excitation energies and the corresponding oscillator strengths of the low-lying electronically excited states for hydrogen-bonded complexes were calculated by time-dependent density functional theory (TDDFT). The ground-state geometric structures were optimized, and it is observed that the intermolecular hydrogen bonds Csbnd N ⋯ Hsbnd O and Nsbnd H ⋯ Osbnd H were formed in PANI-H2O complexes. The formed hydrogen bonds influenced the bond lengths, the charge distribution, as well as the spectral characters of the groups involved. It was concluded that all the hydrogen-bonded PANI-H2O complexes were primarily excited to the S1 states with the largest oscillator strength. In addition, the orbital transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) involved intramolecular charge redistribution resulting to increase the electron density of the quinonoid rings.

  6. Effects of non-exciton components excited by broadband pulses on quantum beats in a GaAs/AlAs multiple quantum well

    Science.gov (United States)

    Kojima, Osamu; Iwasaki, Yuki; Kita, Takashi; Akahane, Kouichi

    2017-01-01

    In this study, we report the effect of the excitation of non-exciton components caused by broadband pulses on quantum beat oscillation. Using a spectrally controlled pump pulse, a long-lived oscillation is clearly observed, and the pump-power dependence shows the suppression of the dephasing rate of the oscillation. Our results from incoherent carrier generation using a continuous wave laser demonstrate that the non-exciton components behaving as free carriers increase the oscillation dephasing rate. PMID:28128344

  7. Exciter switch

    Science.gov (United States)

    Mcpeak, W. L.

    1975-01-01

    A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

  8. Impact of regional left ventricular function on outcome for patients with AL amyloidosis.

    Directory of Open Access Journals (Sweden)

    Dan Liu

    Full Text Available OBJECTIVES: The aim of this study was to explore the left ventricular (LV deformation changes and the potential impact of deformation on outcome in patients with proven light-chain (AL amyloidosis and LV hypertrophy. BACKGROUND: Cardiac involvement in AL amyloidosis patients is associated with poor outcome. Detecting regional cardiac function by advanced non-invasive techniques might be favorable for predicting outcome. METHODS: LV longitudinal, circumferential and radial peak systolic strains (Ssys were assessed by speckle tracking imaging (STI in 44 biopsy-proven systemic AL amyloidosis patients with LV hypertrophy (CA and in 30 normal controls. Patients were divided into compensated (n = 18 and decompensated (n = 26 group based on clinical assessment and followed-up for a median period of 345 days. RESULTS: Ejection fraction (EF was preserved while longitudinal Ssys (LSsys was significantly reduced in both compensated and decompensated groups. Survival was significantly reduced in decompensated group (35% vs. compensated 78%, P = 0.001. LSsys were similar in apical segments and significantly reduced in basal segments between two patient groups. LSsys at mid-segments were significantly reduced in all LV walls of decompensated group. Patients were further divided into 4 subgroups according to the presence or absence of reduced LSsys in no (normal, only basal (mild, basal and mid (intermediate and all segments of the septum (severe. This staging revealed continuously worse prognosis in proportion to increasing number of segments with reduced LSsys (mortality: normal 14%, mild 27%, intermediate 67%, and severe 64%. Mid-septum LSsys<11% suggested a 4.8-fold mortality risk than mid-septum LSsys≥11%. Multivariate regression analysis showed NYHA class and mid-septum LSsys were independent predictors for survival. CONCLUSIONS: Reduced deformation at mid-septum is associated with worse prognosis in systemic amyloidosis patients with LV

  9. Lowest excited states and optical absorption spectra of donor-acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals.

    Science.gov (United States)

    Pandey, Laxman; Doiron, Curtis; Sears, John S; Brédas, Jean-Luc

    2012-11-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated.

  10. Lowest excited states and optical absorption spectra of donor–acceptor copolymers for organic photovoltaics: a new picture emerging from tuned long-range corrected density functionals

    KAUST Repository

    Pandey, Laxman

    2012-01-01

    Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated. © 2012 the Owner Societies.

  11. Fabrication of Al2O3-W Functionally Graded Materials by Slipcasting Method

    Science.gov (United States)

    Katayama, Tomoyuki; Sukenaga, Sohei; Saito, Noritaka; Kagata, Hajime; Nakashima, Kunihiko

    2011-10-01

    We have successfully fabricated a functionally graded material (FGM) from tungsten and alumina powders by a slip-casting method. This FGM has applications as a sealing and conducting component for high-intensity discharge lamps (HiDLs) that have a translucent alumina envelope. Two types of W powder, with different oxidizing properties, were used as the raw powders for the Al2O3-W FGM. "Oxidized W" was prepared by heat-treatment at 200 °C for 180 min in air. Alumina and each of the W powders were mixed in ultrapure water by ultrasonic stirring. The slurry was then cast into a cylindrical acrylic mold, which had a base of porous alumina, under controlled pressure. The green compacts were subsequently dried, and then sintered using a vacuum furnace at 1600 °C for a fixed time. The microstructures of the FGMs were observed by scanning electron microscopy (SEM) of the polished section. The Al2O3-W FGM with the "oxidized W" powder resulted in a microscopic compositional gradient. However, the FGM with "as-received W" showed no compositional gradient. This result was mainly attributed to the difference between the ζ-potentials of the W powders with the different oxidizing conditions; basically "oxidized W" powder tends to disperse because of the larger ζ-potential of the oxide layer coated on the W powder core.

  12. Microstructure and Functional Mechanism of Friction Layer in Ni3Al Matrix Composites with Graphene Nanoplatelets

    Science.gov (United States)

    Xue, Bing; Zhu, Qingshuai; Shi, Xiaoliang; Zhai, Wenzheng; Yang, Kang; Huang, Yuchun

    2016-10-01

    Microstructure and functional mechanism of friction layer need to be further researched. In the present work, the friction coefficients and wear rates are analyzed through response surface methodology to obtain an empirical model for the best response. Fitting results show that the tribological performance of Ni3Al matrix composites (NMCs) with graphene nanoplatelets (GNPs) is better than that of NMCs without GNPs, especially at high sliding velocities and high loads. Further research suggests that the formation of integrated friction layer, which consists of a soft microfilm on a hard coating, is the major reason to cause the differences. Of which, the wear debris layer (WDL) with a low shear strength can reduce the shear force. The ultrafine layer (UL), which is much harder and finer, can effectively avoid fracture and improve the load support capacity. Moreover, the GNPs in WDL and UL can be easily sheared and help to withstand the loads, trending to be parallel to the direction of shear force.

  13. Application of the Sakurai-Sugiura projection method to core-excited-state calculation by time-dependent density functional theory.

    Science.gov (United States)

    Tsuchimochi, Takashi; Kobayashi, Masato; Nakata, Ayako; Imamura, Yutaka; Nakai, Hiromi

    2008-11-15

    The Sakurai-Sugiura projection (SS) method was implemented and numerically assessed for diagonalization of the Hamiltonian in time-dependent density functional theory (TDDFT). Since the SS method can be used to specify the range in which the eigenvalues are computed, it may be an efficient tool for use with eigenvalues in a particular range. In this article, the SS method is applied to core excited calculations for which the eigenvalues are located within a particular range, since the eigenvalues are unique to atomic species in molecules. The numerical assessment of formaldehyde molecule by TDDFT with core-valence Becke's three-parameter exchange (B3) plus Lee-Yang-Parr (LYP) correlation (CV-B3LYP) functional demonstrates that the SS method can be used to selectively obtain highly accurate eigenvalues and eigenvectors. Thus, the SS method is a new and powerful alternative for calculating core-excitation energies without high computation costs.

  14. Transition moments between excited electronic states from the Hermitian formulation of the coupled cluster quadratic response function

    Science.gov (United States)

    Tucholska, Aleksandra M.; Lesiuk, Michał; Moszynski, Robert

    2017-01-01

    We introduce a new method for the computation of the transition moments between the excited electronic states based on the expectation value formalism of the coupled cluster theory [B. Jeziorski and R. Moszynski, Int. J. Quantum Chem. 48, 161 (1993)]. The working expressions of the new method solely employ the coupled cluster operator T and an auxiliary operator S that is expressed as a finite commutator expansion in terms of T and T†. In the approximation adopted in the present paper, the cluster expansion is limited to single, double, and linear triple excitations. The computed dipole transition probabilities for the singlet-singlet and triplet-triplet transitions in alkali earth atoms agree well with the available theoretical and experimental data. In contrast to the existing coupled cluster response theory, the matrix elements obtained by using our approach satisfy the Hermitian symmetry even if the excitations in the cluster operator are truncated, but the operator S is exact. The Hermitian symmetry is slightly broken if the commutator series for the operator S are truncated. As a part of the numerical evidence for the new method, we report calculations of the transition moments between the excited triplet states which have not yet been reported in the literature within the coupled cluster theory. Slater-type basis sets constructed according to the correlation-consistency principle are used in our calculations.

  15. Mice deficient in the ALS2 gene exhibit lymphopenia and abnormal hematopietic function

    OpenAIRE

    2006-01-01

    One form of juvenile onset autosomal recessive amyotrophic lateral sclerosis (ALS2) has been linked to the dysfunction of the ALS2 gene. The ALS2 gene is expressed in lymphoblasts, however, whether ALS2-deficiency affects periphery blood is unclear. Here we report that ALS2 knockout (ALS2−/−) mice developed peripheral lymphopenia but had higher proportions of hematopoietic stem and progenitor cells in which the stem cell factor-induced cell proliferation was up-regulated. Our findings reveal ...

  16. Highly efficient implementation of pseudospectral time-dependent density-functional theory for the calculation of excitation energies of large molecules.

    Science.gov (United States)

    Cao, Yixiang; Hughes, Thomas; Giesen, Dave; Halls, Mathew D; Goldberg, Alexander; Vadicherla, Tati Reddy; Sastry, Madhavi; Patel, Bhargav; Sherman, Woody; Weisman, Andrew L; Friesner, Richard A

    2016-06-15

    We have developed and implemented pseudospectral time-dependent density-functional theory (TDDFT) in the quantum mechanics package Jaguar to calculate restricted singlet and restricted triplet, as well as unrestricted excitation energies with either full linear response (FLR) or the Tamm-Dancoff approximation (TDA) with the pseudospectral length scales, pseudospectral atomic corrections, and pseudospectral multigrid strategy included in the implementations to improve the chemical accuracy and to speed the pseudospectral calculations. The calculations based on pseudospectral time-dependent density-functional theory with full linear response (PS-FLR-TDDFT) and within the Tamm-Dancoff approximation (PS-TDA-TDDFT) for G2 set molecules using B3LYP/6-31G*(*) show mean and maximum absolute deviations of 0.0015 eV and 0.0081 eV, 0.0007 eV and 0.0064 eV, 0.0004 eV and 0.0022 eV for restricted singlet excitation energies, restricted triplet excitation energies, and unrestricted excitation energies, respectively; compared with the results calculated from the conventional spectral method. The application of PS-FLR-TDDFT to OLED molecules and organic dyes, as well as the comparisons for results calculated from PS-FLR-TDDFT and best estimations demonstrate that the accuracy of both PS-FLR-TDDFT and PS-TDA-TDDFT. Calculations for a set of medium-sized molecules, including Cn fullerenes and nanotubes, using the B3LYP functional and 6-31G(**) basis set show PS-TDA-TDDFT provides 19- to 34-fold speedups for Cn fullerenes with 450-1470 basis functions, 11- to 32-fold speedups for nanotubes with 660-3180 basis functions, and 9- to 16-fold speedups for organic molecules with 540-1340 basis functions compared to fully analytic calculations without sacrificing chemical accuracy. The calculations on a set of larger molecules, including the antibiotic drug Ramoplanin, the 46-residue crambin protein, fullerenes up to C540 and nanotubes up to 14×(6,6), using the B3LYP functional and 6-31G

  17. Organic electronic materials: Recent advances in the dft description of the ground and excited states using tuned range-separated hybrid functionals

    KAUST Repository

    Körzdörfer, Thomas

    2014-11-18

    Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers.In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter.We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the

  18. Critical Assessment of Time-Dependent Density Functional Theory for Excited States of Open-Shell Systems: II. Doublet-Quartet Transitions.

    Science.gov (United States)

    Li, Zhendong; Liu, Wenjian

    2016-06-14

    Compared with closed-shell systems, open-shell systems place three additional challenges to time-dependent density functional theory (TD-DFT) for electronically excited states: (a) the spin-contamination problem is a serious issue; (b) the exchange-correlation (XC) kernel may be numerically instable; and (c) the single-determinant description of open-shell ground states readily becomes energetically instable. Confined to flip-up single excitations, the spin-contamination problem can largely be avoided by using the spin-flip TD-DFT (SF-TD-DFT) formalism, provided that a noncollinear XC kernel is employed. As for the numerical instabilities associated with such a kernel, only an ad hoc scheme has been proposed so far, viz., the ALDA0 kernel, which amounts to setting the divergent components (arising from density gradients and kinetic energy density) simply to zero. The ground-state instability problem can effectively be avoided by introducing the Tamm-Dancoff approximation (TDA) to TD-DFT. Therefore, on a general basis, the SF-TDA/ALDA0 Ansatz is so far the only promising means within the TD-DFT framework for flip-up single excitations of open-shell systems. To assess systematically the performance of SF-TDA/ALDA0, in total 61 low-lying quartet excited states of the benchmark set of 11 small radicals [J. Chem. Theory Comput. 2016, 12, 238] are investigated with various XC functionals. Taking the MRCISD+Q (multireference configuration interaction with singles and doubles plus the Davidson correction) results as benchmark, it is found that the mean absolute errors of SF-TDA/ALDA0 with the SAOP (statistical averaging of model orbital potentials), global hybrid, and range-separated hybrid functionals are in the range of 0.2-0.4 eV. This is in line not only with the typical accuracy of TD-DFT for singlet and triplet excited states of closed-shell systems but also with the gross accuracy of spin-adapted TD-DFT for spin-conserving excited states of open-shell systems.

  19. Synthesis and functionalization of monodisperse near-ultraviolet and visible excitable multifunctional Eu3+, Bi3+:REVO4 nanophosphors for bioimaging and biosensing applications

    Science.gov (United States)

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail V.; Ashraf, Sumaira; Hartmann, Raimo; Núñez, Nuria O.; Ocaña, Manuel; Parak, Wolfgang J.

    2016-06-01

    Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be tuned by adjusting the amount of PAA. The Eu- Bi-doped REVO4 based nanophosphors show the typical red luminescence of Eu(iii), which can be excited through an energy transfer process from the vanadate anions, resulting in a much higher luminescence intensity in comparison to the direct excitation of the europium cations. The incorporation of Bi into the REVO4 structure shifts the original absorption band of the vanadate anions towards longer wavelengths, giving rise to nanophosphors with an excitation maximum at 342 nm, which can also be excited in the visible range. The suitability of such nanophosphors for bioimaging and biosensing applications, as well as their colloidal stability in different buffer media of biological interest, their cytotoxicity, their degradability at low pH, and their uptake by HeLa cells have been evaluated. Their suitability for bioimaging and biosensing applications is also demonstrated.Near-ultraviolet and visible excitable Eu- and Bi-doped NPs based on rare earth vanadates (REVO4, RE = Y, Gd) have been synthesized by a facile route from appropriate RE precursors, europium and bismuth nitrate, and sodium orthovanadate, by homogeneous precipitation in an ethylene glycol/water mixture at 120 °C. The NPs can be functionalized either by a one-pot synthesis with polyacrylic acid (PAA) or by a Layer-by-Layer approach with poly(allylamine hydrochloride) (PAH) and PAA. In the first case, the particle size can also be

  20. Microstructures of Al-Al3Ti functionally graded materials fabricated by centrifugal solid-particle method and centrifugal in situ method

    Science.gov (United States)

    Watanabe, Yoshimi; Zhou, Qi; Sato, Hisashi; Fujii, Toshiyuki; Inamura, Tomonari

    2017-01-01

    Methods of fabrication by centrifugal casting for functionally graded materials (FGMs) can be classified into two categories on the basis of the relationship between the process temperature and the liquidus temperature of a master alloy. They are the centrifugal solid-particle method and centrifugal in situ method, which could be carried out at process temperatures lower and higher than the liquidus temperature of the master alloy, respectively. In a previous study, it was found that the microstructures of Al-Al3Ti FGMs fabricated by the centrifugal in situ method processed at 1600 °C were different from those fabricated by the centrifugal solid-particle method processed at 800 °C. Although it is expected that the FGMs fabricated by the centrifugal in situ method processed at approximately the liquidus temperature should show extraordinary microstructures, those microstructures have not been observed. In this study, the microstructures of Al-Al3Ti FGMs fabricated at 1000 °C (centrifugal solid-particle method) and 1200 °C (centrifugal in situ method) were investigated.

  1. Excitable Scale Free Networks

    CERN Document Server

    Copelli, Mauro

    2007-01-01

    When a simple excitable system is continuously stimulated by a Poissonian external source, the response function (mean activity versus stimulus rate) generally shows a linear saturating shape. This is experimentally verified in some classes of sensory neurons, which accordingly present a small dynamic range (defined as the interval of stimulus intensity which can be appropriately coded by the mean activity of the excitable element), usually about one or two decades only. The brain, on the other hand, can handle a significantly broader range of stimulus intensity, and a collective phenomenon involving the interaction among excitable neurons has been suggested to account for the enhancement of the dynamic range. Since the role of the pattern of such interactions is still unclear, here we investigate the performance of a scale-free (SF) network topology in this dynamic range problem. Specifically, we study the transfer function of disordered SF networks of excitable Greenberg-Hastings cellular automata. We obser...

  2. Asymptotic correction of the exchange-correlation kernel of time-dependent density functional theory for long-range charge-transfer excitations.

    Science.gov (United States)

    Gritsenko, Oleg; Baerends, Evert Jan

    2004-07-08

    Time-dependent density functional theory (TDDFT) calculations of charge-transfer excitation energies omegaCT are significantly in error when the adiabatic local density approximation (ALDA) is employed for the exchange-correlation kernel fxc. We relate the error to the physical meaning of the orbital energy of the Kohn-Sham lowest unoccupied molecular orbital (LUMO). The LUMO orbital energy in Kohn-Sham DFT--in contrast to the Hartree-Fock model--approximates an excited electron, which is correct for excitations in compact molecules. In CT transitions the energy of the LUMO of the acceptor molecule should instead describe an added electron, i.e., approximate the electron affinity. To obtain a contribution that compensates for the difference, a specific divergence of fxc is required in rigorous TDDFT, and a suitable asymptotically correct form of the kernel fxc(asymp) is proposed. The importance of the asymptotic correction of fxc is demonstrated with the calculation of omegaCT(R) for the prototype diatomic system HeBe at various separations R(He-Be). The TDDFT-ALDA curve omegaCT(R) roughly resembles the benchmark ab initio curve omegaCT CISD(R) of a configuration interaction calculation with single and double excitations in the region R=1-1.5 A, where a sizable He-Be interaction exists, but exhibits the wrong behavior omegaCT(R)excitations in compact systems and fxc(asymp) for weakly interacting fragments and suitable interpolation expressions are considered.

  3. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants.

    Science.gov (United States)

    Zarycz, M Natalia C; Provasi, Patricio F; Sauer, Stephan P A

    2015-12-28

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH4, NH3, H2O, SiH4, PH3, SH2, C2H2, C2H4, and C2H6. The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states.

  4. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    Energy Technology Data Exchange (ETDEWEB)

    Zarycz, M. Natalia C., E-mail: mnzarycz@gmail.com; Provasi, Patricio F., E-mail: patricio@unne.edu.ar [Department of Physics, University of Northeastern - CONICET, Av. Libertad 5500, Corrientes W3404AAS (Argentina); Sauer, Stephan P. A., E-mail: sauer@kiku.dk [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark)

    2015-12-28

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCCs), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections of the Polarization Propagator (IPPP-CLOPPA) approach to analyzing SSCCs in terms of localized orbitals. As a test set we have studied the nine simple compounds, CH{sub 4}, NH{sub 3}, H{sub 2}O, SiH{sub 4}, PH{sub 3}, SH{sub 2}, C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}. The excited (pseudo)states were obtained from time-dependent density functional theory (TD-DFT) calculations with the B3LYP exchange-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states.

  5. HgNO3 sensitivity of AlGaN/GaN field effect transistors functionalized with phytochelating peptides

    Science.gov (United States)

    Rohrbaugh, Nathaniel; Hernandez-Balderrama, Luis; Kaess, Felix; Kirste, Ronny; Collazo, Ramon; Ivanisevic, Albena

    2016-06-01

    This study examined the conductance sensitivity of AlGaN/GaN field effect transistors in response to varying Hg/HNO3 solutions. FET surfaces were covalently functionalized with phytochelatin-5 peptides in order to detect Hg in solution. Results showed a resilience of peptide-AlGaN/GaN bonds in the presence of strong HNO3 aliquots, with significant degradation in FET ID signal. However, devices showed strong and varied response to Hg concentrations of 1, 10, 100, and 1000 ppm. The gathered statistically significant results indicate that peptide terminated AlGaN/GaN devices are capable of differentiating between Hg solutions and demonstrate device sensitivity.

  6. Excited states

    CERN Document Server

    Lim, Edward C

    1974-01-01

    Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

  7. Formation of Sm sup 2 sup + ions in femtosecond laser excited Al sub 2 O sub 3 - SiO sub 2 glasses

    CERN Document Server

    Park, G J; Nogami, M

    2003-01-01

    Al sub 2 O sub 3 - SiO sub 2 glasses doped with Sm sup 3 sup + ions were irradiated with an 800 nm wavelength femtosecond laser pulse and the formation of Sm sup 2 sup + ions was investigated. The Sm sup 3 sup + ions were reduced to Sm sup 2 sup + within a few minutes of laser irradiation. Electron spin resonance spectra indicated that the hole was trapped in non-bridging oxygen bound to Al sup 3 sup + , while the electron was captured in the Sm sup 3 sup + , leading to the Sm sup 2 sup + formation. The thermal stability of the photoinduced Sm sup 2 sup + ions was also investigated by fluorescence spectroscopy. The Sm sup 2 sup + ions were converted to Sm sup 3 sup + ions by heating the glasses in air at 300- 400 deg. C.

  8. Anharmonicity of multi-octupole-phonon excitations in $^{208}$Pb: analysis with multi-reference covariant density functional theory and subbarrier fusion of $^{16}$O+$^{208}$Pb

    CERN Document Server

    Yao, J M

    2016-01-01

    We discuss anharmonicity of the multi-octupole-phonon states in $^{208}$Pb based on a covariant density functional theory, by fully taking into account the interplay between the quadrupole and the octupole degrees of freedom. Our results indicate the existence of a large anharmonicity in the transition strengths, even though the excitation energies are similar to those in the harmonic limit. We also show that the quadrupole-shape fluctuation significantly enhances the fragmentation of the two-octupole-phonon states in $^{208}$Pb. Using those transition strengths as inputs to coupled channels calculations, we then discuss the fusion reaction of $^{16}$O+$^{208}$Pb at energies around the Coulomb barrier. We show that the anharmonicity of the octupole vibrational excitation considerably improves previous coupled-channels calculations in the harmonic oscillator limit, significantly reducing the height of the main peak in the fusion barrier distribution.

  9. On the truncation of the number of excited states in density functional theory sum-over-states calculations of indirect spin spin coupling constants

    DEFF Research Database (Denmark)

    Zarycz, M. Natalia C.; Provasi, Patricio F.; Sauer, Stephan P. A.

    2015-01-01

    It is investigated, whether the number of excited (pseudo)states can be truncated in the sum-over-states expression for indirect spin-spin coupling constants (SSCC), which is used in the Contributions from Localized Orbitals within the Polarization Propagator Approach and Inner Projections......-correlation functional and the specialized core-property basis set, aug-cc-pVTZ-J. We investigated both how the calculated coupling constants depend on the number of (pseudo)states included in the summation and whether the summation can be truncated in a systematic way at a smaller number of states and extrapolated...... to the total number of (pseudo)states for the given one-electron basis set. We find that this is possible and that for some of the couplings it is sufficient to include only about 30% of the excited (pseudo)states....

  10. SYNTHESIS OF FUNCTIONAL MACROMOLECULE INTERMEDIATE THROUGH ACYLATION CATALYZED BY [Emim]Cl-AlCl3 IONIC LIQUID

    Institute of Scientific and Technical Information of China (English)

    CHEN Min; JIANG Deli; ZHANG Chunyan; YU Long; YAN Yongsheng

    2007-01-01

    Acylation reaction of anthracene with oxalyl chloride in the presence of [Emim]Cl-AlCl3 ionic liquid has been investigated. Pure 1,2-aceanthryenedione, which is used as intermediate of functional aromatic polymer material, was obtained by recrystalling the reaction mixture with aether and was determined by GC/MS, 1HNMR and FTIR analysis. The influences of various parameters,such as the contents of AlCl3 in [Emim]Cl-AlCl3, the amount of acylation agent, amount of [Emim]Cl-AlCl3, reaction temperature and reaction time were investigated. The optimum conditions were as follows: the molar fraction of AlCl3 in ionic liquid [x(AlCl3)] being 0.67, molar ratio of ionic liquid to anthracene being 2:1, molar ratio of oxalyl chloride to anthracene being 2:1,reaction temperature being 40 ℃ and reaction time being 6h. Under above conditions, the yield and selectivity of 1,2-aceanthrylenedione can reach 91.5% and 98.3% respectively. Further more,[Emim]Cl-AlCl3 ionic liquid, compared with metal halides such as AlCl3, was found to catalyze the reaction as a novel environmental friendly catalyst and solvent and can be reused.

  11. Excited states of large open-shell molecules: an efficient, general, and spin-adapted approach based on a restricted open-shell ground state wave function.

    Science.gov (United States)

    Roemelt, Michael; Neese, Frank

    2013-04-11

    A spin-adapted configuration interaction with singles method that is based on a restricted open-shell reference function (ROCIS) with general total spin S is presented. All excited configuration state functions (CSFs) are generated with the aid of a spin-free second quantization formalism that only leads to CSFs within the first order interacting space. By virtue of the CSF construction, the formalism involves higher than singly excited determinants but not higher than singly excited configurations. Matrix elements between CSFs are evaluated on the basis of commutator relationships using a symbolic algebra program. The final equations were, however, hand-coded in order to maximize performance. The method can be applied to fairly large systems with more than 100 atoms in reasonable wall-clock times and also parallelizes well. Test calculations demonstrate that the approach is far superior to UHF-based configuration interaction with single excitations but necessarily falls somewhat short of quantitative accuracy due to the lack of dynamic correlation contributions. In order to implicitly account for dynamic correlation in a crude way, the program optionally allows for the use of Kohn-Sham orbitals in combination with a modest downscaling of two-electron integrals (DFT/ROCIS). All two-electron integrals of Kohn-Sham orbitals that appear in the Hamiltonian matrix are reduced by a total of three scaling parameters that are suitable for a wide range of molecules. Test calculations on open-shell organic radicals as well as transition metal complexes demonstrate the wide applicability of the method and its ability to calculate the electronic spectra of large molecular systems.

  12. Corrosion and wear behavior of functionally graded Al2024/SiC composites produced by hot pressing and consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Fatih; Canakci, Aykut, E-mail: aykut@ktu.edu.tr; Varol, Temel; Ozkaya, Serdar

    2015-09-25

    Highlights: • Functionally graded Al2024/SiC composites were produced by hot pressing. • Effect of the number of graded layers was investigated on the corrosion behavior. • Functionally graded composites has the most corrosion resistant than composites. • Wear mechanisms of Al2024/SiC composites were explained. - Abstract: Functionally graded Al2024/SiC composites (FGMs) with varying percentage of SiC (30–60%) were produced by hot pressing and consolidation method. The effects of SiC content and number of layers of Al2024/SiC FGMs on the corrosion and wear behaviors were investigated. The microstructures of these composites were characterized by a scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The corrosion performances of composites were evaluated by potentiodynamic polarization scans in 3.5% NaCl solution. Corrosion experiments shows that corrosion rate (1109 mpy) of two layered FGMs which containing 50 wt.% SiC were much higher than Al2024 matrix (2569 mpy) and Al2024/50 wt.% SiC composite (2201 mpy). Mechanical properties of these composites were evaluated by microhardness measurements and ball-on-disk wear tests. As the applied load change from 15 to 20 N, the wear rates of the Al2024 increased significantly and wear mechanism transformed from mild to severe wear regime. It has been shown that Al2024/40 wt.% SiC composite has lower wear rate where adhesive and abrasive wear mechanisms play a major role.

  13. Microstructural analysis of the radial distribution function for liquid and amorphous Al

    CERN Document Server

    Li, G X; Zhu, Z G; Liu, C S

    2003-01-01

    Constant-pressure molecular dynamics simulations and analysis of the local atomic structures have been performed to study the conventional and 'inherent' structural evolution of liquid Al during rapid solidification. The results show that the radial distribution functions g(r) exhibit a second-peak splitting feature not only for the general structures of the amorphous states but also for the inherent structure of liquid states. The second peak of g(r) decomposes into three main components, each corresponding to different pairs. The first subpeak in the inherent structure of the liquid arises from 2211 and 2331 pairs (which correspond to triangles with a common side and the tetrahedra sharing a face respectively), while the first subpeak in the amorphous state arises from 2331 pairs; in both cases the second subpeak is due to the 2101 pairs (linear trimers). The existence of a shoulder or the splitting in the second peak of g(r) in the amorphous state, and even in the undercooled liquid state, results mainly f...

  14. Ni–Fe–Al$_2$O$_3$ electrodeposited nanocomposite coating with functionally graded microstructure

    Indian Academy of Sciences (India)

    V TORABINEJAD; A SABOUR ROUHAGHDAM; M ALIOFKHAZRAEI; M H ALLAHYARZADEH

    2016-06-01

    In this study, a Ni–Fe–Al$_2$O$_3$ nanocomposite coating was deposited on the substrate of low-carbon steel by electrodeposition from a sulphate-based bath. The effects of frequency and duty cycle were investigated to producethe functionally graded (FG) coating. For this purpose, first, the coatings with duty cycle-decreased method (DDM) were deposited in eight steps from 88 to 11%. At the second step, frequency-increased method (FIM) was utilized from 50 to 6400 Hz during eight steps. Assessing of coatings was carried out by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), potentiodynamic test, Vickers microhardness test and wear test.Microstructure evaluations gained by SEM and EDS demonstrated that the continuous alterations of duty cycle contribute for manufacturing of FG coatings, so that the maximum particle fraction was in the free surface of the coating and its amount was gradually decreased to the interface. These investigations showed that FIM had no effect on production of graded structure. Corrosion and wear tests indicated high corrosion and wear resistance of DDM coatings in comparison to FIM coatings. Investigating the best coatings obtained from both above methods exhibited 50 and 20% reduction in corrosion current density and wear rate, respectively, for DDM specimen in comparison to FIM sample.

  15. Time-course of corticospinal excitability and autonomic function interplay during and following monopolar tDCS

    Directory of Open Access Journals (Sweden)

    Emiliano eSantarnecchi

    2014-07-01

    Full Text Available While polarity-specific after-effects of monopolar transcranial direct current stimulation (tDCS on cortico-spinal excitability are well-documented, modulation of vital parameters due to current spread through the brainstem is still a matter of debate, raising potential concerns about its use through the general public, as well as for neurorehabilitation purposes. We monitored online and after-effects of monopolar tDCS (primary motor cortex in ten healthy subjects by adopting a neuronavigated transcranial magnetic stimulation (TMS/tDCS combined protocol. Motor evoked potentials (MEPs together with vital parameters (e.g. blood pressure, heart-rate variability and sympathovagal balance were recorded and monitored before, during and after anodal, cathodal or sham tDCS. Ten MEPs every 2.5-minute time windows were recorded from the right First Dorsal Interosseus (FDI, while 5-minute epochs were used to record vital parameters. The protocol included 15 minutes of pre-tDCS and of online-tDCS, (anodal, cathodal or sham. After effects were recorded for 30 minutes. We showed a polarity-independent stabilization of cortical excitability level, a polarity-specific after-effects for cathodal and anodal stimulation, and an absence of persistent excitability changes during online stimulation. No significant effects on vital parameters emerged both during and after tDCS, while a linear increase in systolic/diastolic blood pressure and heart-rate variability was observed during each tDCS condition, as a possible unspecific response to experimental demands. Taken together, current findings provide new insights on the safety of monopolar tDCS, promoting its application both in research and clinical settings.

  16. Computational Materials Science Network Team on ''Excited states and response functions''

    Energy Technology Data Exchange (ETDEWEB)

    Sokrates T. Pantelides

    2005-04-22

    This report covers the final one-year period of work done by the Principal Investigator (S. T. Pantelides) and his group in collaboration with other team members. The focus of the work was to pursue understanding of core excitation spectra in doped manganites where experimental data obtained at Oak Ridge National Laboratory by S. J. Pennycook showed inequivalent Mn atoms. Calculations found that doping sets up a Peierls-like instability that drives the observed distortion. Further calculations of electron-energy-loss spectra to account for the observed L23 ratios in the Mn L2,3 spectra will be pursued in the future.

  17. Charge-transfer pipi* excited state in the 7-azaindole dimer. A hybrid configuration interactions singles/time-dependent density functional theory description.

    Science.gov (United States)

    Gelabert, Ricard; Moreno, Miquel; Lluch, José M

    2006-01-26

    The hybrid configuration interaction singles/time dependent density functional theory approach of Dreuw and Head-Gordon [Dreuw, A.; Head-Gordon, M. J. Am. Chem. Soc. 2004, 126, 4007] has been applied to study the potential energy landscape and accessibility of the charge-transfer pipi* excited state in the dimer of 7-azaindole, which has been traditionally considered a model for DNA base pairing. It is found that the charge-transfer pipi* excited state preferentially stabilizes the product of a single proton transfer. In this situation, the crossing between this state and the photoactive electronic state of the dimer is accessible. It is found that the charge-transfer pipi* excited state has a very steep potential energy profile with respect to any single proton-transfer coordinate and, in contrast, an extremely flat potential energy profile with respect to the stretch of the single proton-transfer complex. This is predicted to bring about a pair of rare fragments of the 7-azaindole dimer, physically separated and hence having very long lifetimes. This could have implications in the DNA base pairs of which the system is an analogue, in the form of replication errors.

  18. Time-dependent density functional theory study on the electronic excited-state geometric structure, infrared spectra, and hydrogen bonding of a doubly hydrogen-bonded complex.

    Science.gov (United States)

    Liu, Yufang; Ding, Junxia; Liu, Ruiqiong; Shi, Deheng; Sun, Jinfeng

    2009-12-01

    The geometric structures and infrared (IR) spectra in the electronically excited state of a novel doubly hydrogen-bonded complex formed by fluorenone and alcohols, which has been observed by IR spectra in experimental study, are investigated by the time-dependent density functional theory (TDDFT) method. The geometric structures and IR spectra in both ground state and the S(1) state of this doubly hydrogen-bonded FN-2MeOH complex are calculated using the DFT and TDDFT methods, respectively. Two intermolecular hydrogen bonds are formed between FN and methanol molecules in the doubly hydrogen-bonded FN-2MeOH complex. Moreover, the formation of the second intermolecular hydrogen bond can make the first intermolecular hydrogen bond become slightly weak. Furthermore, it is confirmed that the spectral shoulder at around 1700 cm(-1) observed in the IR spectra should be assigned as the doubly hydrogen-bonded FN-2MeOH complex from our calculated results. The electronic excited-state hydrogen bonding dynamics is also studied by monitoring some vibraitonal modes related to the formation of hydrogen bonds in different electronic states. As a result, both the two intermolecular hydrogen bonds are significantly strengthened in the S(1) state of the doubly hydrogen-bonded FN-2MeOH complex. The hydrogen bond strengthening in the electronically excited state is similar to the previous study on the singly hydrogen-bonded FN-MeOH complex and play important role on the photophysics of fluorenone in solutions.

  19. Electronic Excitations in Push-Pull Oligomers and Their Complexes with Fullerene from Many-Body Green's Functions Theory with Polarizable Embedding.

    Science.gov (United States)

    Baumeier, Björn; Rohlfing, Michael; Andrienko, Denis

    2014-08-12

    We present a comparative study of excited states in push-pull oligomers of PCPDTBT and PSBTBT and prototypical complexes with a C60 acceptor using many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation. We analyze excitations in oligomers up to a length of 5 nm and find that for both materials the absorption energy practically saturates for structures larger than two repeat units due to the localized nature of the excitation. In the bimolecular complexes with C60, the transition from Frenkel to charge transfer excitons is generally exothermic and strongly influenced by the acceptor's position and orientation. The high CT binding energy of the order of 2 eV results from the lack of an explicit molecular environment. External polarization effects are then modeled in a GW-BSE based QM/MM approach by embedding the donor-acceptor complex into a polarizable lattice. The lowest charge transfer exciton is energetically stabilized by about 0.5 eV, while its binding energy is reduced to about 0.3 eV. We also identify a globally unbound charge transfer state with a more delocalized hole at higher energy while still within the absorption spectrum, which opens another potential pathway for charge separation. For both PCPDTBT and PSBTBT, the energetics are largely similar with respect to absorption and the driving force to form intermediate charge transfer excitations for free charge generation. These results support that the higher power conversion efficiency observed for solar cells using PSBTBT as donor material is a result of molecular packing rather than of the electronic structure of the polymer.

  20. Determination and systematics of excitation functions for the production of {sup 36}Cl by means of AMS

    Energy Technology Data Exchange (ETDEWEB)

    Sudbrock, F.; Herpers, U. [Koeln Univ. (Germany); Synal, H.A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Suter, M. [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Gloris, M.; Michel, R. [Hannover Univ. (Germany)

    1997-09-01

    Studies concerning the production of the long-lived radionuclides {sup 10}Be, {sup 26}Al and {sup 36}Cl measured via accelerator mass spectrometry have been continued. Recently measured data on the production of {sup 36}Cl by medium and high energy protons are discussed. (author) 1 figs., 4 refs.

  1. Combining density functional and density matrix theory: Optical excitation and electron relaxation at the Si(001)2 x 1 surface

    Energy Technology Data Exchange (ETDEWEB)

    Buecking, Norbert [Institut fuer Theoretische Physik, Technische Universitaet Berlin (Germany); Fritz-Haber-Institut der MPG, Berlin (Germany); Kratzer, Peter [Fachbereich Physik, Duisburg (Germany); Scheffler, Matthias [Fritz-Haber-Institut der MPG, Berlin (Germany); Knorr, Andreas [Institut fuer Theoretische Physik, Technische Universitaet Berlin (Germany)

    2008-07-01

    A theoretical two-step approach to investigate the optical excitation and subsequent phonon-assisted relaxation dynamics at semiconductor surfaces is presented and applied to the Si(001)2 x 1-surface: In the first step, the electronic band structure and the Kohn-Sham wave functions are calculated by density-functional-theory (DFT) within the LDA. In the second step, dynamical equations are derived from density-matrix theory (DMT), whereby an optical field is considered via A.p-coupling and phonon induced relaxation by a deformation potential coupling term. Into these equations, the numerical results of the DFT calculation (Kohn-Sham eigenvalues and wave functions) enter as coupling matrix elements. By numerically solving the dynamical equations, the time-resolved population of the excited states can be evaluated. The results for the Si(001) surface correspond to the findings of recent experiments, in particular a short (intra-surface-band scattering) and a long (bulk-surface band scattering) timescale are dominating the relaxation process. The value of the experimental short timescale is reproduced by our calculations, whereas the long timescale cannot be accurately described by our theory.

  2. Solvent effects on optical excitations of poly para phenylene ethynylene studied by QM/MM simulations based on many-body Green's functions theory

    Science.gov (United States)

    Bagheri, B.; Karttunen, M.; Baumeier, B.

    2016-07-01

    Electronic excitations in dilute solutions of poly para phenylene ethynylene (poly-PPE) are studied using a QM/MM approach combining many-body Green's functions theory within the GW approximation and the Bethe-Salpeter equation with polarizable force field models. Oligomers up to a length of 7.5 nm (10 repeat units) functionalized with nonyl side chains are solvated in toluene and water, respectively. After equilibration using atomistic molecular dynamics (MD), the system is partitioned into a quantum region (backbone) embedded into a classical (side chains and solvent) environment. Optical absorption properties are calculated solving the coupled QM/MM system self-consistently and special attention is paid to the effects of solvents. The model allows to differentiate the influence of oligomer conformation induced by the solvation from electronic effects related to local electric fields and polarization. It is found that the electronic environment contributions are negligible compared to the conformational dynamics of the conjugated PPE. An analysis of the electron-hole wave function reveals a sensitivity of energy and localization characteristics of the excited states to bends in the global conformation of the oligomer rather than to the relative of phenyl rings along the backbone.

  3. Reversible hydrogen storage by NaAlH4 confined within a titanium-functionalized MOF-74(Mg) nanoreactor.

    Science.gov (United States)

    Stavila, Vitalie; Bhakta, Raghunandan K; Alam, Todd M; Majzoub, Eric H; Allendorf, Mark D

    2012-11-27

    We demonstrate that NaAlH(4) confined within the nanopores of a titanium-functionalized metal-organic framework (MOF) template MOF-74(Mg) can reversibly store hydrogen with minimal loss of capacity. Hydride-infiltrated samples were synthesized by melt infiltration, achieving loadings up to 21 wt %. MOF-74(Mg) possesses one-dimensional, 12 Å channels lined with Mg atoms having open coordination sites, which can serve as sites for Ti catalyst stabilization. MOF-74(Mg) is stable under repeated hydrogen desorption and hydride regeneration cycles, allowing it to serve as a "nanoreactor". Confining NaAlH(4) within these pores alters the decomposition pathway by eliminating the stable intermediate Na(3)AlH(6) phase observed during bulk decomposition and proceeding directly to NaH, Al, and H(2), in agreement with theory. The onset of hydrogen desorption for both Ti-doped and undoped nano-NaAlH(4)@MOF-74(Mg) is ∼50 °C, nearly 100 °C lower than bulk NaAlH(4). However, the presence of titanium is not necessary for this increase in desorption kinetics but enables rehydriding to be almost fully reversible. Isothermal kinetic studies indicate that the activation energy for H(2) desorption is reduced from 79.5 kJ mol(-1) in bulk Ti-doped NaAlH(4) to 57.4 kJ mol(-1) for nanoconfined NaAlH(4). The structural properties of nano-NaAlH(4)@MOF-74(Mg) were probed using (23)Na and (27)Al solid-state MAS NMR, which indicates that the hydride is not decomposed during infiltration and that Al is present as tetrahedral AlH(4)(-) anions prior to desorption and as Al metal after desorption. Because of the highly ordered MOF structure and monodisperse pore dimensions, our results allow key template features to be identified to ensure reversible, low-temperature hydrogen storage.

  4. Time-resolved spectroscopy in LiCaAlF{sub 6} doped with Cr{sup 3+}: dynamical Jahn-Teller effect and thermal shifts associated with the {sup 4}T{sub 2} excited state

    Energy Technology Data Exchange (ETDEWEB)

    Sanz-Ortiz, M N; Rodriguez, F [MALTA CONSOLIDER Team, DCITIMAC, Facultad de Ciencias, Universidad de Cantabria, E-39005 Santander (Spain); Valiente, R, E-mail: rodriguf@unican.e [MALTA CONSOLIDER Team, Departamento Fisica Aplicada, Facultad de Ciencias, Universidad de Cantabria, E-39005 Santander (Spain)

    2010-03-31

    This work investigates the centre distribution of the Cr{sup 3+} impurity, the dynamical Jahn-Teller effect in the first {sup 4}T{sub 2} excited state and the thermal shifts of the absorption and emission peaks in LiCaAlF{sub 6}:Cr{sup 3+} by means of time-resolved emission spectroscopy. The electronic and vibrational fine structure observed in both the absorption and emission spectra at low temperature are assigned according to the vibrational modes of the internal (CrF{sub 6}){sup 3-} complex and the lattice modes. Zero-phonon lines associated with {sup 4}T{sub 2}->{sup 4}A{sub 2} and E{sup 2}->{sup 4}A{sub 2} transitions were detected and assigned on the basis of available high pressure data in LiCaAlF{sub 6}:Cr{sup 3+}. We have identified the vibrational coupled modes responsible for the vibrational structure of the low temperature emission spectrum and the reduction of the zero-phonon line (ZPL) splitting caused by the dynamical Jahn-Teller effect in the {sup 4}T{sub 2} excited state (Huang-Rhys factor, S{sub e} = 0.92). In addition, from the temperature variation of the emission intensity I(T), transition energy E(T) and bandwidth H(T), we obtained the vibrational modes that are coupled to the emitting state. We have evaluated the two main contributions to the photoluminescence thermal shift through thermal expansion and high pressure measurements: the implicit contribution induced by changes of thermal population and the explicit contribution induced by thermal expansion effects-40% and 60% of the total shift, respectively.

  5. On the excitation spectra of Cr{sup 3+}/Cr{sup 2+} and V{sup 3+} co-doped ZnAl{sub 2}S{sub 4} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Anghel, S., E-mail: anggell@gmail.com [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of); Ruhr-Universität Bochum, Anorganische Chemie III, Universitätsstrasse 150, D-44801 Bochum (Germany); Brik, M.G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Ravila 14 C, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw (Poland); Ma, C.-G. [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Sushkevich, K. [State University of Moldova, Mateevici Str 60, Chis,inău MD-2009, Republic of Moldova (Moldova, Republic of); Kulyuk, L. [Institute of Applied Physics, Academiei Str 5, Chis,inău MD-2028, Republic of Moldova (Moldova, Republic of)

    2015-10-15

    The excitation spectra of the ZnAl{sub 2}S{sub 4} spinel crystals codoped with chromium and vanadium are investigated in order to explain some features of the Cr{sup 3+} ions optical spectra and the inconsistency of the experimental absorption/emission bands position with the Tanabe–Sugano diagram, as well as the “missing” band in the absorption spectrum of V{sup 3+} ion although this band should be present as it is due to a spin allowed transition. The unusual high Racah parameters of the C/B ratio for Cr{sup 3+} ions have been induced to recalculate the Tanabe–Sugano diagram for the d{sup 3} electron configuration and the ratio C/B=8 in order to use it for the experimental results interpretation. The presence of Cr{sup 2+} ions in the low spin electron configurations in the octahedral coordination was confirmed; the temperature dependence of the Cr{sup 2+} emission at about 1.9 eV was studied and the Huang–Rhys factors were estimated for different temperatures. Despite the fact that the V{sup 3+}C/B ratio has a different value compared to the case of Cr{sup 3+} ions, the electron–phonon interaction is similar for both ions, with the Huang–Rhys parameter equal to 10 in both cases. Further research into optimizing the ZnAl{sub 2}S{sub 4}:Cr, V system to get an efficient enhancement of the vanadium emission on account on re-absorbing the chromium emission is suggested. - Highlights: • The spectroscopic properties of Cr and V codoped α-ZnAI{sub 2}S{sub 4} have been investigated. • The crystal field calculations have been performed. • The Huang–Rhys factors have been estimated for different temperatures. • The theoretical calculations have been correlated with the excitation spectra.

  6. Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions

    Directory of Open Access Journals (Sweden)

    Webster TJ

    2013-01-01

    Full Text Available Alexandra P Ross, Thomas J WebsterSchool of Engineering and Department of Orthopedics, Brown University, Providence, RI, USAAbstract: Current titanium-based implants are often anodized in sulfuric acid (H2SO4 for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone–implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study

  7. Anodizing color coded anodized Ti6Al4V medical devices for increasing bone cell functions.

    Science.gov (United States)

    Ross, Alexandra P; Webster, Thomas J

    2013-01-01

    Current titanium-based implants are often anodized in sulfuric acid (H(2)SO(4)) for color coding purposes. However, a crucial parameter in selecting the material for an orthopedic implant is the degree to which it will integrate into the surrounding bone. Loosening at the bone-implant interface can cause catastrophic failure when motion occurs between the implant and the surrounding bone. Recently, a different anodization process using hydrofluoric acid has been shown to increase bone growth on commercially pure titanium and titanium alloys through the creation of nanotubes. The objective of this study was to compare, for the first time, the influence of anodizing a titanium alloy medical device in sulfuric acid for color coding purposes, as is done in the orthopedic implant industry, followed by anodizing the device in hydrofluoric acid to implement nanotubes. Specifically, Ti6Al4V model implant samples were anodized first with sulfuric acid to create color-coding features, and then with hydrofluoric acid to implement surface features to enhance osteoblast functions. The material surfaces were characterized by visual inspection, scanning electron microscopy, contact angle measurements, and energy dispersive spectroscopy. Human osteoblasts were seeded onto the samples for a series of time points and were measured for adhesion and proliferation. After 1 and 2 weeks, the levels of alkaline phosphatase activity and calcium deposition were measured to assess the long-term differentiation of osteoblasts into the calcium depositing cells. The results showed that anodizing in hydrofluoric acid after anodizing in sulfuric acid partially retains color coding and creates unique surface features to increase osteoblast adhesion, proliferation, alkaline phosphatase activity, and calcium deposition. In this manner, this study provides a viable method to anodize an already color coded, anodized titanium alloy to potentially increase bone growth for numerous implant applications.

  8. Angular distribution, kinetic energy distributions, and excitation functions of fast metastable oxygen fragments following electron impact of CO2

    Science.gov (United States)

    Misakian, M.; Mumma, M. J.; Faris, J. F.

    1975-01-01

    Dissociative excitation of CO2 by electron impact was studied using the methods of translational spectroscopy and angular distribution analysis. Earlier time of flight studies revealed two overlapping spectra, the slower of which was attributed to metastable CO(a3 pi) fragments. The fast peak is the focus of this study. Threshold energy, angular distribution, and improve time of flight measurements indicate that the fast peak actually consists of five overlapping features. The slowest of the five features is found to consist of metastable 0(5S) produced by predissociation of a sigma u + state of CO2 into 0(5S) + CO(a3 pi). Oxygen Rydberg fragments originating directly from a different sigma u + state are believed to make up the next fastest feature. Mechanisms for producing the three remaining features are discussed.

  9. High energy-resolution studies of electron impact optical excitation functions. I - The second positive system of N2.

    Science.gov (United States)

    Finn, T. G.; Doering, J. P.; Aarts, J. F. M.

    1972-01-01

    The relative emission cross section for the N2 second positive system (0,0) and (1,0) bands excited by electron impact was measured for incident electron energies from threshold to 17 eV. The use of a high energy-resolution electron spectrometer coupled to an optical detection system made it possible to obtain the measurements with an incident electron beam having an energy half width of 50 meV. Calibration of the incident electron energy was provided by observing the scattering resonances in nitrogen and helium. The maximum of the (0,0) and (1,0) bands were found to be at approximately 14.02 and 14.3 eV, respectively. A small structural feature that was pressure-independent appeared only in the (0,0) band emission cross section. Another such feature was pressure-dependent and appeared more strongly in the (1,0) band cross section.

  10. Functional group induced excited state intramolecular proton transfer process in 4-amino-2-methylsulfanyl-pyrimidine-5-carboxylic acid ethyl ester: a combined spectroscopic and density functional theory study.

    Science.gov (United States)

    Jana, Sankar; Dalapati, Sasanka; Guchhait, Nikhil

    2013-09-01

    The molecule methyl-2-aminonicotinate (2-MAN) does not exhibit excited state intramolecular proton transfer (ESIPT), but its derivative 4-amino-2-methylsulfanyl-pyrimidine-5-carboxylic acid ethyl ester (AMPCE), widely used in the preparation of pyrimidopyrimidines as a protein kinase inhibitor, does exhibit ESIPT. Increasing acidic and basic character at the proton donor and proton acceptor sites by adding functional groups is found to be responsible for the large Stokes shifted ESIPT emission (Δν = 12,706 cm(-1)) in AMPCE. The photophysics of AMPCE have been explored on the basis of steady state and time resolved spectral measurements, quantum yield calculation with variation of polarity, as well as hydrogen bonding ability of solvents. Experimental findings have been correlated with the calculated structure and potential energy surfaces based on the intramolecular proton transfer model obtained by density functional theory (DFT). Properties based on the calculated excited state surfaces generated in vacuo and methanol solvent using time dependent density functional theory (TDDFT) and time dependent density functional theory polarized continuum model (TDDFT-PCM), respectively, show good agreement with the experimental findings. HOMO and LUMO diagrams also support the favorable ESIPT process in the first excited state potential energy surface.

  11. Gain-of-function mutations in the ALS8 causative gene VAPB have detrimental effects on neurons and muscles

    Directory of Open Access Journals (Sweden)

    Mario Sanhueza

    2013-12-01

    Amyotrophic Lateral Sclerosis (ALS is a motor neuron degenerative disease characterized by a progressive, and ultimately fatal, muscle paralysis. The human VAMP-Associated Protein B (hVAPB is the causative gene of ALS type 8. Previous studies have shown that a loss-of-function mechanism is responsible for VAPB-induced ALS. Recently, a novel mutation in hVAPB (V234I has been identified but its pathogenic potential has not been assessed. We found that neuronal expression of the V234I mutant allele in Drosophila (DVAP-V260I induces defects in synaptic structure and microtubule architecture that are opposite to those associated with DVAP mutants and transgenic expression of other ALS-linked alleles. Expression of DVAP-V260I also induces aggregate formation, reduced viability, wing postural defects, abnormal locomotion behavior, nuclear abnormalities, neurodegeneration and upregulation of the heat-shock-mediated stress response. Similar, albeit milder, phenotypes are associated with the overexpression of the wild-type protein. These data show that overexpressing the wild-type DVAP is sufficient to induce the disease and that DVAP-V260I is a pathogenic allele with increased wild-type activity. We propose that a combination of gain- and loss-of-function mechanisms is responsible for VAPB-induced ALS.

  12. Functional regions of Candida albicans hyphal cell wall protein Als3 that determine interaction with the oral bacterium Streptococcus gordonii.

    Science.gov (United States)

    Bamford, Caroline V; Nobbs, Angela H; Barbour, Michele E; Lamont, Richard J; Jenkinson, Howard F

    2015-01-01

    The opportunistic pathogen Candida albicans colonizes the oral cavity and gastrointestinal tract. Adherence to host cells, extracellular matrix and salivary glycoproteins that coat oral surfaces, including prostheses, is an important prerequisite for colonization. In addition, interactions of C. albicans with commensal oral streptococci are suggested to promote retention and persistence of fungal cells in mixed-species communities. The hyphal filament specific cell wall protein Als3, a member of the Als protein family, is a major determinant in C. albicans adherence. Here, we utilized site-specific in-frame deletions within Als3 expressed on the surface of heterologous Saccharomyces cerevisiae to determine regions involved in interactions of Als3 with Streptococcus gordonii. N-terminal region amino acid residue deletions Δ166-225, Δ218-285, Δ270-305 and Δ277-286 were each effective in inhibiting binding of Strep. gordonii to Als3. In addition, these deletions differentially affected biofilm formation, hydrophobicity, and adherence to silicone and human tissue proteins. Deletion of the central repeat domain (Δ434-830) did not significantly affect interaction of Als3 with Strep. gordonii SspB protein, but affected other adherence properties and biofilm formation. Deletion of the amyloid-forming region (Δ325-331) did not affect interaction of Als3 with Strep. gordonii SspB adhesin, suggesting this interaction was amyloid-independent. These findings highlighted the essential function of the N-terminal domain of Als3 in mediating the interaction of C. albicans with S. gordonii, and suggested that amyloid formation is not essential for the inter-kingdom interaction.

  13. Multireference configuration interaction potential curve and analytical potential energy function of the ground and low-lying excited states of CdSe

    Institute of Scientific and Technical Information of China (English)

    Gao Feng; Yang Chuan-Lu; Hu Zhen-Yan; Wang Mei-Shan

    2007-01-01

    The potential energy curves (PECs) of the ground state (3Π) and three low-lying excited states (1∑, 3∑,1Π) of CdSe dimer have been studied by emploging quasirelativistic effective core potentials on the basis of the complete active space self-consistent field method followed by multireference configuration interaction calculation. The four PECs are fitted to analytical potential energy functions using the Murrel-Sorbie potential function. Based on the PECs,the vibrational levels of the four states are determined by solving the Schr(o)dinger equation of nuclear motion, and corresponding spectroscopic contants are accurately calculated. The equilibrium positions as well as the spectroscopic constants and the vibrational levels are reported. By our analysis, the 3Π state, of which the dissociation asymptote is Cd(1S) + Se(3p), is identified as a ground state of CdSe dimer, and the corresponding dissociation energy is estimated to be 0.39eV. However, the first excited state is only 1132.49cm-1 above the ground state and the 3∑ state is the highest in the four calculated states.

  14. Spin-Orbit-Enhanced Functionality in LaAlO3/SrTiO3 Nanostructures

    Science.gov (United States)

    2015-09-16

    two- dimensional electron gas and conductivity switching of nanowires at the LaAlO3/SrTiO3 interface grown by 90° off-axis sputtering," Applied...rectangular area that is 200 nm wide. Transport experiments are performed as a function of a plane-perpendicular magnetic field up to 50 kOe, and as a... insulator transition of the LaAlO3/SrTiO3 interface with a conductive-atomic force microscope (c-AFM) technique has enabled a variety of electrical and

  15. Physisorption of functionalized gold nanoparticles on AlGaN/GaN high electron mobility transistors for sensing applications.

    Science.gov (United States)

    Makowski, M S; Kim, S; Gaillard, M; Janes, D; Manfra, M J; Bryan, I; Sitar, Z; Arellano, C; Xie, J; Collazo, R; Ivanisevic, A

    2013-02-18

    AlGaN/GaN high electron mobility transistors (HEMTs) were used to measure electrical characteristics of physisorbed gold nanoparticles (Au NPs) functionalized with alkanethiols with a terminal methyl, amine, or carboxyl functional group. Additional alkanethiol was physisorbed onto the NP treated devices to distinguish between the effects of the Au NPs and alkanethiols on HEMT operation. Scanning Kelvin probe microscopy and electrical measurements were used to characterize the treatment effects. The HEMTs were operated near threshold voltage due to the greatest sensitivity in this region. The Au NP/HEMT system electrically detected functional group differences on adsorbed NPs which is pertinent to biosensor applications.

  16. Density functional theory studies on the structures and water-exchange reactions of aqueous Al(III)-oxalate complexes.

    Science.gov (United States)

    Jin, Xiaoyan; Yan, Yu; Shi, Wenjing; Bi, Shuping

    2011-12-01

    The structures and water-exchange reactions of aqueous aluminum-oxalate complexes are investigated using density functional theory. The present work includes (1) The structures of Al(C(2)O(4))(H(2)O)(4)(+) and Al(C(2)O(4))(2)(H(2)O)(2)(-) were optimized at the level of B3LYP/6-311+G(d,p). The geometries obtained suggest that the Al-OH(2) bond lengths trans to C(2)O(4)(2-) ligand in Al(C(2)O(4))(H(2)O)(4)(+) are much longer than the Al-OH(2) bond lengths cis to C(2)O(4)(2-). For Al(C(2)O(4))(2)(H(2)O)(2)(-), the close energies between cis and trans isomers imply the coexistence in aqueous solution. The (27)Al NMR and (13)C NMR chemical shifts computed with the consideration of sufficient solvent effect using HF GIAO method and 6-311+G(d,p) basis set are in agreement with the experimental values available, indicating the appropriateness of the applied models; (2) The water-exchange reactions of Al(III)-oxalate complexes were simulated at the same computational level. The results show that water exchange proceeds via dissociative pathway and the activation energy barriers are sensitive to the solvent effect. The energy barriers obtained indicate that the coordinated H(2)O cis to C(2)O(4)(2-) in Al(C(2)O(4))(H(2)O)(4)(+) is more labile than trans H(2)O. The water-exchange rate constants (k(ex)) of trans- and cis-Al(C(2)O(4))(2)(H(2)O)(2)(-) were estimated by four methods and their respective characteristics were explored; (3) The significance of the study on the aqueous aluminum-oxalate complexes to environmental chemistry is discussed. The influences of ubiquitous organic ligands in environment on aluminum chemistry behavior can be elucidated by extending this study to a series of Al(III)-organic system.

  17. Solvent effects on optical excitations of poly para phenylene ethynylene studied by QM/MM simulations based on Many-Body Green's Functions Theory

    CERN Document Server

    Bagheri, Behnaz; Baumeier, Björn

    2016-01-01

    Electronic excitations in dilute solutions of poly para phenylene ethynylene (poly-PPE) are studied using a QM/MM approach combining many-body Green's functions theory within the $GW$ approximation and the Bethe-Salpeter equation with polarizable force field models. Oligomers up to a length of 7.5\\,nm (10 repeat units) functionalized with nonyl side chains are solvated in toluene and water, respectively. After equilibration using atomistic molecular dynamics (MD), the system is partitioned into a quantum region (backbone) embedded into a classical (side chains and solvent) environment. Optical absorption properties are calculated solving the coupled QM/MM system self-consistently and special attention is paid to the effects of solvents. The model allows to differentiate the influence of oligomer conformation induced by the solvation from electronic effects related to local electric fields and polarization. It is found that the electronic environment contributions are negligible compared to the conformational ...

  18. Predictions of Optical Excitations in Transition-Metal Complexes with Time Dependent-Density Functional Theory:  Influence of Basis Sets.

    Science.gov (United States)

    Petit, Laurence; Maldivi, Pascale; Adamo, Carlo

    2005-09-01

    The calculation of the absorption spectra of four families of transition-metal complexes (Ni(CO)4, MnO4(-), MF6 (M = Cr, Mo, W) and CpM(CO)2 (M = Rh, Ir)) has been undertaken to unravel the influence of basis sets onto excitation energies, oscillator strengths, and assignments. Three among the most common pseudopotentials, with the corresponding valence basis sets, and two all-electron basis sets have been used for the metal center description in the framework of the time dependent Density Functional Theory (TD-DFT). Our results show that this approach does not particularly depend on the basis set used on the metal atoms. Furthermore, the chosen functional PBE0 provides transitions in good agreement with experiments, and it provides an accuracy of about 0.3 eV, comparable to that of refined post-Hartree-Fock methods.

  19. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems.

    Science.gov (United States)

    van Meer, R; Gritsenko, O V; Baerends, E J

    2014-01-14

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ωα and oscillator strengths fα for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ωα(R) curves along the bond dissociation coordinate R for the molecules LiH, Li2, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate.

  20. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems

    Energy Technology Data Exchange (ETDEWEB)

    Meer, R. van; Gritsenko, O. V. [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands); WCU Program, Dep. of Chemistry, Pohang Univ. of Science and Techn., Pohang (Korea, Republic of); Baerends, E. J. [Faculty of Exact Sciences, Theoretical Chemistry, VU University, Amsterdam (Netherlands); WCU Program, Dep. of Chemistry, Pohang Univ. of Science and Techn., Pohang (Korea, Republic of); Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-01-14

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ω{sub α} and oscillator strengths f{sub α} for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ω{sub α}(R) curves along the bond dissociation coordinate R for the molecules LiH, Li{sub 2}, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate.

  1. Excited baryons

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, N.C.

    1986-01-01

    The status of the theory of the low-energy approach to hadron structure is reviewed briefly by surveying a few relevant models. A few examples of tests needed to sort out the predictions of different models pertaining to the quark-gluon structure of hadrons are discussed, and given the resulting physics objectives, a few experimental options for excited baryon research at CFBAF are suggested. (LEW)

  2. Functionally graded coating for steels by reaction diffusion using FeAl{sub 3} powder

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, Y.

    2000-10-01

    The powder liquid coating method has successfully been applied to a commercially available pure iron and a carbon steel (JIS-545C) using FeAl{sub 3} powder. The coated layer is found well graded in terms of microstructure, chemical compositions and hardness, so that the costed layer is much stronger for thermal shock than that made by a conventional aluminizing method. Changes in the graded microstructure during coating procedures are studied; it is noted that an FeAl/FeAl{sub 2}, eutectoid Structure formed in the coated layer shows 927HV and relatively high toughness. Although the present coating technique needs to heat a sample up to an elevated temperature as high as 1,473 K, the prior austenite grain size of the carbon steel was refined by so-called Grange method, without accompanying any serious damages in the coated layer. (author)

  3. Towards bridging the gap between acid-base transporters and neuronal excitability modulation

    OpenAIRE

    2014-01-01

    pH homeostasis is a fundamental regulator of the function of the central nervous system. Dysfunction of acid-base transporters often results in disturbance of neuronal excitability. In a latest issue of Journal of Neuroscience, Jones et al. report that increasing intracellular bicarbonate concentration substantially stimulates the excitability of pyramidal neurons from mouse hippocampus by inhibiting KCNQ potassium channel. The finding shed important new light in understanding the molecular m...

  4. Calculation of Vibrational and Electronic Excited-State Absorption Spectra of Arsenic-Water Complexes Using Density Functional Theory

    Science.gov (United States)

    2016-06-03

    calculations geometry optimization and vibrational analysis was effected using the DFT model B3LYP [29, 30] and basis function 6-311+G(d) [31, 32...of Arsenic-Water Complexes Using Density Functional Theory June 3, 2016 Approved for public release; distribution is unlimited. L. Huang S.g...LambrakoS Center for Computational Materials Science Materials Science and Technology Division a. SHabaev George Mason University Fairfax, Virginia L. maSSa

  5. UV excitations of halons

    Science.gov (United States)

    Stojanović, Ljiljana; Alyoubi, Abdulrahman O.; Aziz, Saadullah G.; Hilal, Rifaat H.; Barbatti, Mario

    2016-11-01

    In the present study, we examined the UV excitations of a newly introduced molecular set, Halons-9, composed of nine gaseous halon molecules. The performance of the density functional-based multi-reference configuration interaction method (DFT/MRCI) and time-dependent density functional theory with CAM-B3LYP functional (TD-CAM-B3LYP) in the computation of singlet and triplet excited states of this set was evaluated against coupled-cluster with singles and doubles (CCSD). Excited states up to the corresponding ionization limits, including both localized and delocalized excitations, have been benchmarked. TD-CAM-B3LYP significantly underestimates excitation energies of the higher mixed valence-Rydberg and Rydberg states, with computed mean absolute deviations from the equation of motion (EOM)-CCSD results 1.06 and 0.76 eV, respectively. DFT/MRCI gives a significantly better description of higher excited states, albeit still poor, compared to the TD-CAM-B3LYP. The mean absolute deviations of mixed valence-Rydberg and Rydberg states from the reference EOM-CCSD values are 0.66 and 0.47 eV, respectively. The performance of DFT/MRCI for description of strongly correlated states with valence-Rydberg mixing is still not satisfactory enough. On the other hand, oscillator strengths of most of singlet states obtained with both methods are close to the EOM-CCSD values. The largest deviations, occurring in the case of several high-lying multiconfigurational states, are of an order of magnitude.

  6. Assessment of density functional theory based ΔSCF (self-consistent field) and linear response methods for longest wavelength excited states of extended π-conjugated molecular systems

    Energy Technology Data Exchange (ETDEWEB)

    Filatov, Michael, E-mail: mike.filatov@gmail.com [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstr. 4, D-53115 Bonn (Germany); Huix-Rotllant, Miquel, E-mail: miquel.huix@gmail.com [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main (Germany)

    2014-07-14

    Computational investigation of the longest wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a ΔSCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these π-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended π-conjugated systems with the accuracy matching high-level ab initio multireference calculations.

  7. Assessment of density functional theory based Î'SCF (self-consistent field) and linear response methods for longest wavelength excited states of extended π-conjugated molecular systems

    Science.gov (United States)

    Filatov, Michael; Huix-Rotllant, Miquel

    2014-07-01

    Computational investigation of the longest wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a ΔSCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these π-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended π-conjugated systems with the accuracy matching high-level ab initio multireference calculations.

  8. Assessment of density functional theory based ΔSCF (self-consistent field) and linear response methods for longest wavelength excited states of extended π-conjugated molecular systems.

    Science.gov (United States)

    Filatov, Michael; Huix-Rotllant, Miquel

    2014-07-14

    Computational investigation of the longest wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a ΔSCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these π-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended π-conjugated systems with the accuracy matching high-level ab initio multireference calculations.

  9. Optical excitation and electron relaxation dynamics at semiconductor surfaces: a combined approach of density functional and density matrix theory applied to the silicon (001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Buecking, N.

    2007-11-05

    In this work a new theoretical formalism is introduced in order to simulate the phononinduced relaxation of a non-equilibrium distribution to equilibrium at a semiconductor surface numerically. The non-equilibrium distribution is effected by an optical excitation. The approach in this thesis is to link two conventional, but approved methods to a new, more global description: while semiconductor surfaces can be investigated accurately by density-functional theory, the dynamical processes in semiconductor heterostructures are successfully described by density matrix theory. In this work, the parameters for density-matrix theory are determined from the results of density-functional calculations. This work is organized in two parts. In Part I, the general fundamentals of the theory are elaborated, covering the fundamentals of canonical quantizations as well as the theory of density-functional and density-matrix theory in 2{sup nd} order Born approximation. While the formalism of density functional theory for structure investigation has been established for a long time and many different codes exist, the requirements for density matrix formalism concerning the geometry and the number of implemented bands exceed the usual possibilities of the existing code in this field. A special attention is therefore attributed to the development of extensions to existing formulations of this theory, where geometrical and fundamental symmetries of the structure and the equations are used. In Part II, the newly developed formalism is applied to a silicon (001)surface in a 2 x 1 reconstruction. As first step, density-functional calculations using the LDA functional are completed, from which the Kohn-Sham-wave functions and eigenvalues are used to calculate interaction matrix elements for the electron-phonon-coupling an the optical excitation. These matrix elements are determined for the optical transitions from valence to conduction bands and for electron-phonon processes inside the

  10. Functional Characterization of Shape Memory CuZnAl Open-Cell Foams by Molten Metal Infiltration

    Science.gov (United States)

    Arnaboldi, S.; Bassani, P.; Passaretti, F.; Redaelli, A.; Tuissi, A.

    2011-07-01

    In the recent years, the research for novel materials with tailored mechanical properties, as well as functional properties, has encouraged the study of porous and cellular materials. Our previous work proposed and reported about the possibility to manufacture open-cell metal foams of CuZnAl shape memory alloy by liquid infiltration in a leachable bed of silica-gel particles. This innovative methodology is based on cheap commercial consumables and a simple technology, focusing on intermediate-density low-cost foams with interesting cost/benefits ratio. Microstructural analyses on foamed specimens showed uniform microstructure of ligaments and a very regular and well reproducible open-cell morphology. Moreover, calorimetric analysis detected a thermo-elastic martensitic transformation in the foamed material. In this study, a CuZnAl shape memory alloy was considered and tested to clarify possible effects of the foaming process on the functional properties of the material. Morphological, calorimetric, and thermo-mechanical analyses were carried out. The results show that it is possible to produce metal foams of CuZnAl shape memory alloy with different functional properties and able to recover mono-axial compressive strains up to 3%.

  11. Transient resonance Raman spectroscopy and density functional theory investigation of iso-CHBr 2Cl and iso-CCl 3Br photoproducts produced following ultraviolet excitation of CHBr 2Cl and CCl 3Br

    OpenAIRE

    Zheng, X; Lee, CW; Li, YL; Fang, WH; Phillips, DL

    2001-01-01

    Two polyhalomethanes that contain bromine and chlorine atoms (CHBr 2Cl and CCl 2Br) were studied. Transient resonance Raman spectra were obtained for the photoproducts produced after ultraviolet excitation of CHBr 2Cl and CCl 3Br in room temperature solutions and density functional theory calculations for species proposed to be products of the photodissociation reactions in the solution phase. It was found that the iso-CHBrCl-Br and iso-CHClBr-Br species are formed following ultraviolet excit...

  12. Double excitation effect in non-adiabatic time-dependent density functional theory with an analytic construction of the exchange-correlation kernel in the common energy denominator approximation.

    Science.gov (United States)

    Gritsenko, Oleg V; Baerends, Evert Jan

    2009-06-14

    Time-dependent density functional (response) theory (TDDF(R)T) is applied almost exclusively in its adiabatic approximation (ATDDFT), which is restricted to predominantly single electronic excitations and neglects additional roots of the TDDFT eigenvalue problem stemming from the interaction between single and double excitations. We incorporate the effect of the latter interaction into a non-adiabatic frequency-dependent and spatially non-local Hartree-exchange-correlation (Hxc) kernel fCEDAHxc (r1, r2, omega), the explicit analytical expression of which is derived for interacting single and double excitations well separated from the other excitations, within the common energy denominator approximation (CEDA) for the Kohn-Sham (KS) and interacting density response functions, chis and chi, respectively. The kernel fCEDAHxc (r1, r2, omega) obtained from the direct analytical inverse of chiCEDAs and chiCEDA is a sum of the delta-function and non-local orbital-dependent spatial terms with frequency-dependent factors, with which fCEDAHxc acquires a modulated quadratic dependence on omega. The effective incorporation in fCEDAHxc of the complete manifold of excited states (through the delta function term) represents an extension of the kernel reported by Maitra, Zhang, Cave, and Burke [J. Chem. Phys., 2004, 120, 5932]. In the TDDFT eigenvalue equations considered in the diagonal approximation, fCEDAHxc generates two excitation energies omegaq and omegaq+1, which both correspond to the same single KS excitation omegasq, thus producing the effect of the single-double excitation interaction.

  13. Muscle-Derived GDNF: A Gene Therapeutic Approach for Preserving Motor Neuron Function in ALS

    Science.gov (United States)

    2015-08-01

    neural progenitor cells (hNPC) secreting GDNF to the spinal of SOD1G93A rats protects motor neurons from degeneration. Supported by the California...56S-61S. 12. Suzuki, M., et al., GDNF secreting human neural progenitor cells protect dying motor neurons, but not their projection to muscle, in a rat ...into astrocytes, and no tumor formation following transplantation into the spinal cord of immunocompromised rats . Neuroreport, 2013. 21. Emborg, M.E

  14. Evidence of shell effects in the excitation function of 0.136-MeV isomeric state populated in the 93Nb (n,2n) 92Nbm reaction

    Science.gov (United States)

    Gul, K.

    2004-09-01

    Calculation for the excitation function of 0.136-MeV ( 2+ ) isomeric state in 92Nb has been carried out using Hauser-Feshbach and pre-equilibrium nuclear reaction models in 10 20 MeV energy range. A satisfactory agreement between the calculation and measurements requires the suppression of contribution from the negative-parity doublet consisting of the 0.226-MeV ( 2- ) and 0.390-MeV ( 3- ) states in 92Nb . This can be explained on the basis of highly retarded gamma transitions of higher energy states to the negative-parity doublet on account of its different shell model configuration compared to the shell model configuration of positive-parity states.

  15. Subsystem density-functional theory as an effective tool for modeling ground and excited states, their dynamics and many-body interactions

    Science.gov (United States)

    Krishtal, Alisa; Sinha, Debalina; Genova, Alessandro; Pavanello, Michele

    2015-05-01

    Subsystem density-functional theory (DFT) is an emerging technique for calculating the electronic structure of complex molecular and condensed phase systems. In this topical review, we focus on some recent advances in this field related to the computation of condensed phase systems, their excited states, and the evaluation of many-body interactions between the subsystems. As subsystem DFT is in principle an exact theory, any advance in this field can have a dual role. One is the possible applicability of a resulting method in practical calculations. The other is the possibility of shedding light on some quantum-mechanical phenomenon which is more easily treated by subdividing a supersystem into subsystems. An example of the latter is many-body interactions. In the discussion, we present some recent work from our research group as well as some new results, casting them in the current state-of-the-art in this review as comprehensively as possible.

  16. An efficient formulation and implementation of the analytic energy gradient method to the single and double excitation coupled-cluster wave function - Application to Cl2O2

    Science.gov (United States)

    Rendell, Alistair P.; Lee, Timothy J.

    1991-01-01

    The analytic energy gradient for the single and double excitation coupled-cluster (CCSD) wave function has been reformulated and implemented in a new set of programs. The reformulated set of gradient equations have a smaller computational cost than any previously published. The iterative solution of the linear equations and the construction of the effective density matrices are fully vectorized, being based on matrix multiplications. The new method has been used to investigate the Cl2O2 molecule, which has recently been postulated as an important intermediate in the destruction of ozone in the stratosphere. In addition to reporting computational timings, the CCSD equilibrium geometries, harmonic vibrational frequencies, infrared intensities, and relative energetics of three isomers of Cl2O2 are presented.

  17. Ab initio calculations of accurate dissociation energy and analytic potential energy function for the second excited state B1П of 7LiH

    Institute of Scientific and Technical Information of China (English)

    Shi De-Heng; Liu Yu-Fang; Sun Jin-Feng; Zhu Zun-Lùe; Yang Xiang-Dong

    2006-01-01

    The reasonable dissociation limit of the second excited singlet state B1П of 7LiH molecule is obtained. The obtained over the internuclear distance ranging from about 0.10 nm to 0.54 nm, and has a least-square fit to the analytic compared with previous theoretical results. The equilibrium internuclear distance obtained by geometry optimization is found to be quite different from that obtained by single-point energy scanning under the same calculation condition.comparison of the theoretical calculations of dissociation energies, equilibrium interatomic distances and the analytic potential energy function with those obtained by previous theoretical results clearly shows that the present work is more theories.

  18. Effect of entrance channel parameters on the fusion of two heavy ions: Excitation functions of reaction products in 16O+66Zn and 37Cl + 45Sc reactions

    Indian Academy of Sciences (India)

    Suparne Sodaye; B S Tomar; A Goswami

    2006-06-01

    Excitation functions of reaction products formed in 16O+66Zn and 37Cl + 45Sc systems, leading to the same compound nucleus, 82Sr, were measured using recoilcatcher technique and off-line -ray spectrometry. The contribution of non-compound processes like transfer and incomplete fusion (ICF) reactions to the cross-sections of different evaporation residues were delineated by comparing the experimental data with the predictions of Monte Carlo simulation code PACE2. The results show that non-compound processes become a significant fraction of the total reaction cross-section in 16O+66Zn systems in the beam energy range studied, while 37Cl + 45Sc gives mainly compound nucleus products. The mass asymmetry dependence of the fusion and non-compound cross-sections have been analysed in terms of the static fusion model and sum rule model.

  19. Complete and incomplete fusion of $^{12}C$ with $^{165}Ho$ below 7 MeV/nucleon Measurements and analysis of excitation functions

    CERN Document Server

    Gupta, S; Musthafa, M M; Bhardwaj, H D; Prasadl, R

    2000-01-01

    This experiment has been done with a view to studying complete and incomplete fusion in heavy-ion-induced reactions. Excitation functions for several reactions induced by /sup 12/C/sup 5+/ ions on /sup 165/Ho at incident energies from 55 to 80 MeV have been measured using the activation technique. The analysis of the data has been done using the codes ALICE-91 and CASCADE. The parameter F/sub theta /, the ratio of actual moment of inertia to the rigid-body value, has been found to play an important role in the calculations done by the code CASCADE. Significant contributions from both the complete and the incomplete fusion channels have been observed. Further, in the case of the reaction (C, p3n) considerable contribution from the decay of higher charge isobar precursor has been observed. (23 refs).

  20. Absence of Magnetic Dipolar Phase Transition and Evolution of Low-Energy Excitations in PrNb2Al20 with Crystal Electric Field Γ3 Ground State: Evidence from 93Nb-NQR Studies

    Science.gov (United States)

    Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

    2015-07-01

    We report measurements of bulk magnetic susceptibility and 93Nb nuclear quadrupole resonance (NQR) in the Pr-based caged compound PrNb2Al20. By analyzing the magnetic susceptibility and magnetization, the crystal electric field (CEF) level scheme of PrNb2Al20 is determined to be Γ3(0 K)-Γ4(21.32 K)-Γ5(43.98 K)-Γ1(51.16 K) within the framework of the localized 4f electron picture. The 93Nb-NQR spectra exhibit neither spectral broadening nor spectral shift upon cooling down to 75 mK. The 93Nb-NQR spin-lattice relaxation rate 1/T1 at 5 K depends on the frequency and remains almost constant below 5 K. The frequency dependence of 1/T1 is attributed to the magnetic fluctuation due to the hyperfine-enhanced 141Pr nuclear moment inherent in the nonmagnetic Γ3 CEF ground state. The present NQR results provide evidence that no symmetry-breaking magnetic dipole order occurs down to 75 mK. Also, considering an invariant form of the quadrupole and octupole couplings between a 93Nb nucleus and Pr 4f electrons, Pr 4f quadrupoles and an octupole can couple with a 93Nb nuclear quadrupole moment and nuclear spin, respectively. Together with the results of bulk measurements, the present NQR results suggest that the possibility of a static quadrupole or octupole ordering can be excluded down to 100 mK. At low temperatures below 500 mK, however, the nuclear spin-echo decay rate gradually increases and the decay curve changes from Gaussian decay to Lorentzian decay, suggesting the evolution of a low-energy excitation.

  1. Distinct and shared functions of ALS-associated proteins TDP-43, FUS and TAF15 revealed by multisystem analyses.

    Science.gov (United States)

    Kapeli, Katannya; Pratt, Gabriel A; Vu, Anthony Q; Hutt, Kasey R; Martinez, Fernando J; Sundararaman, Balaji; Batra, Ranjan; Freese, Peter; Lambert, Nicole J; Huelga, Stephanie C; Chun, Seung J; Liang, Tiffany Y; Chang, Jeremy; Donohue, John P; Shiue, Lily; Zhang, Jiayu; Zhu, Haining; Cambi, Franca; Kasarskis, Edward; Hoon, Shawn; Ares, Manuel; Burge, Christopher B; Ravits, John; Rigo, Frank; Yeo, Gene W

    2016-07-05

    The RNA-binding protein (RBP) TAF15 is implicated in amyotrophic lateral sclerosis (ALS). To compare TAF15 function to that of two ALS-associated RBPs, FUS and TDP-43, we integrate CLIP-seq and RNA Bind-N-Seq technologies, and show that TAF15 binds to ∼4,900 RNAs enriched for GGUA motifs in adult mouse brains. TAF15 and FUS exhibit similar binding patterns in introns, are enriched in 3' untranslated regions and alter genes distinct from TDP-43. However, unlike FUS and TDP-43, TAF15 has a minimal role in alternative splicing. In human neural progenitors, TAF15 and FUS affect turnover of their RNA targets. In human stem cell-derived motor neurons, the RNA profile associated with concomitant loss of both TAF15 and FUS resembles that observed in the presence of the ALS-associated mutation FUS R521G, but contrasts with late-stage sporadic ALS patients. Taken together, our findings reveal convergent and divergent roles for FUS, TAF15 and TDP-43 in RNA metabolism.

  2. Excited state geometry optimization with the density matrix renormalization group as applied to polyenes

    CERN Document Server

    Hu, Weifeng

    2015-01-01

    We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al (J. Chem. Theor.Comput. 9, 4462 (2013)). We introduce a DMRG wavefunction maximum overlap following technique to facilitate state-specific DMRG excited state optimization. Using DMRG configuration interaction (DMRG-CI) gradients we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited state geometries as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.

  3. In-situ Al/24Si Functional Graded Materials Prepared by Electromagnetic Separation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Cylinder-like in-situ Al/24Si FGMs were produced by using electromagnetic separating process. Si primary phasereinforced layer with volume fraction as high as 16 pct was formed at the outer region of the cylinder-like sampleswhere the local hardness and wear resistance were enhanced remarkably. Moreover, both of strength and ductility inthe inner region provided insurance of reliable strength for this as-cast gradient material. It indicated that generalmechanical properties such as good wear resistance at the outer region and good ductility in the central part couldbe obtained with the optimized redistribution of the Si primary particles under the electromagnetic force.

  4. The functionalities of Pt/{gamma}-Al{sub 2}O{sub 3} catalysts in simultaneous HDS and HDA reactions

    Energy Technology Data Exchange (ETDEWEB)

    V.G. Baldovino-Medrano; Sonia A. Giraldo; Aristobulo Centeno [Universidad Industrial de Santander (UIS), Bucaramanga (Colombia). Centro de Investigaciones en Catalisis (CICAT)

    2008-08-15

    A Pt/{gamma}-Al{sub 2}O{sub 3} catalyst was tested in simultaneous hydrodesulfurization (HDS) of dibenzothiophene and hydrodearomatization (HDA) of naphthalene reactions. Samples of it were subjected to different pretreatments: reduction, reduction-sulfidation, sulfidation with pure H{sub 2}S and non-activation. The reduced catalyst presented the best performance, even comparable to that of Co(Ni)Mo catalysts. All catalyst samples were selective to the HDS reaction over HDA, and to the direct desulfurization pathway of dibenzothiophene HDS over the hydrogenation reaction pathway of HDS. The effect of H{sub 2}S partial pressure on the functionalities of the reduced Pt/{gamma}-Al{sub 2}O{sub 3} catalyst was studied. The results showed that an increase in H{sub 2}S partial pressure does not cause poisoning, but an inhibition effect, without changing the catalyst selectivity. Accordingly, the activity trends were ascribed to adsorption differences between the different reactive molecules over the same catalytic active site. TPR characterization along with a thermodynamics analysis showed that the active phase of reduced Pt/{gamma}-Al{sub 2}O{sub 3} is constituted by Pt{sup 0} particles. However, presulfidation of the catalyst leads to a mixture of PtS and Pt{sup 0}which has a negative effect on the catalytic performance without changing catalyst functionalities. 61 refs., 4 figs., 1 tab.

  5. Analysis of energy autocorrelation functionsin dissipative heavy ion collision of 27Al+27Al

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The excitation functions were measured in the reaction of27Al+27Al at incidentenergies from 114 MeV to 127 MeV in steps of 200 keV. Thedetection angles were continuouslycovered from 10 to 57 in the laboratory system. Theenergy autocorrelation functions of the dissipativefragmentswere analyzed by using different approaches. The nonself-averaging oscillations in theexcitation functions were considered due to the angular momentum coherence and damping ofthe coherent nuclear rotation. The damping results from a quantum chaotic motion.

  6. Studying the effects of the configuration of doped Al atoms on the conductive properties of boron nitride nanotube using density functional theory

    Science.gov (United States)

    Tavangar, Zahra; Hamadanian, Masood; Basharnavaz, Hadi

    2017-02-01

    In this paper, we study the effects of the configuration of two Al atoms doped into the unit cell of (7, 0) BNNTs, on their structural and electronic properties in solid state using density functional theory methods. Also, all possible configurations for Al double doped (7, 0) BNNT were investigated. The results showed that with Al doping, band gap decreased. Furthermore, an impurity state appears near the Fermi level when two Al atoms replace two boron atoms of adjacent layers. Contour plots of charge density distribution showed a protuberance surrounding N and B atoms adjacent to the substitute Al atoms.

  7. Cerebellar cortex granular layer interneurons in the macaque monkey are functionally driven by mossy fiber pathways through net excitation or inhibition.

    Directory of Open Access Journals (Sweden)

    Jean Laurens

    Full Text Available The granular layer is the input layer of the cerebellar cortex. It receives information through mossy fibers, which contact local granular layer interneurons (GLIs and granular layer output neurons (granule cells. GLIs provide one of the first signal processing stages in the cerebellar cortex by exciting or inhibiting granule cells. Despite the importance of this early processing stage for later cerebellar computations, the responses of GLIs and the functional connections of mossy fibers with GLIs in awake animals are poorly understood. Here, we recorded GLIs and mossy fibers in the macaque ventral-paraflocculus (VPFL during oculomotor tasks, providing the first full inventory of GLI responses in the VPFL of awake primates. We found that while mossy fiber responses are characterized by a linear monotonic relationship between firing rate and eye position, GLIs show complex response profiles characterized by "eye position fields" and single or double directional tunings. For the majority of GLIs, prominent features of their responses can be explained by assuming that a single GLI receives inputs from mossy fibers with similar or opposite directional preferences, and that these mossy fiber inputs influence GLI discharge through net excitatory or inhibitory pathways. Importantly, GLIs receiving mossy fiber inputs through these putative excitatory and inhibitory pathways show different firing properties, suggesting that they indeed correspond to two distinct classes of interneurons. We propose a new interpretation of the information flow through the cerebellar cortex granular layer, in which mossy fiber input patterns drive the responses of GLIs not only through excitatory but also through net inhibitory pathways, and that excited and inhibited GLIs can be identified based on their responses and their intrinsic properties.

  8. Tunable Excited-State Properties and Dynamics as a Function of Pt–Pt Distance in Pyrazolate-Bridged Pt(II) Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Brown-Xu, Samantha E.; Kelley, Matthew S. J.; Fransted, Kelly A.; Chakraborty, Arnab; Schatz, George C.; Castellano, Felix N.; Chen, Lin X.

    2016-02-04

    The influence of molecular structure on excited state properties and dynamics of a series of cyclometalated platinum dimers was investigated through a combined experimental and theoretical approach using femtosecond transient absorption (fs TA) spectroscopy and density functional theory (DFT) calculations. The molecules have the general formula [Pt(ppy)(µ-R2pz)]2 where ppy = 2-phenylpyridine, pz = pyrazolate and R = H, Me, Ph, or tBu, and are strongly photoluminescent at room temperature. The distance between the platinum centers in this A frame geometry can be varied depending on the steric bulk of the bridging pyrazolate ligands that exert structural constraints and compress the Pt-Pt distance. At large Pt-Pt distances there is little interaction between the subunits and the chromophore behaves similar to a monomer with excited states described as mixtures of ligand-centered and metal-to-ligand charge transfer (LC/MLCT) transitions. When the Pt(II) centers are brought closer together with bulky bridging ligands, they interact through their orbitals and the S1 and T1 states are best characterized as metal metal to ligand charge transfer (MMLCT) in character. The results of the fs TA experiments reveal that intersystem crossing (ISC) occurs on ultrafast timescales (τS1 < 200 fs) while there are two relaxation processes occurring within the triplet manifold, τ1 = 0.5 – 3.2 ps and τ2 = 20 – 70 ps; the longer time constants correspond to the presence of bulkier bridging ligands. DFT calculations illustrate that the Pt-Pt distances further contract in the T1 3MMLCT states, therefore slower relaxation may be related to a larger structural reorganization. Subsequent investigations using faster time resolution are planned to measure the ISC process as well as to identify any potential coherent interaction(s) between the platinum centers that may occur.

  9. Preparation of functionalized porous nano-γ-Al2O3 powders employing colophony extract

    Directory of Open Access Journals (Sweden)

    Ángela B. Sifontes

    2014-12-01

    Full Text Available This study reports the synthesis of porous nano alumina employing carboxylato-alumoxanes [Al(Ox(OHy(O2CRz]n as precursors for controlling the pore size, pore size distribution and porosity of the alumina, using a new process ecofriendly. The carboxylato-alumoxanes was prepared by the reaction of boehmite with carboxylic acids. The boehmite was obtained by the hydrolysis of aluminum alkoxide in an aqueous solution. The colophony extract is employed as a source of carboxylic acids. The materials were characterized, using XRD, TGA, N2 physical adsorption, SEM, TEM, NMR and FTIR. A mechanism was proposed for the formation of the synthesized structures. TEM measurements confirmed particle size ranged from 5 to 8 nm.

  10. 基于PID预测函数的励磁控制研究%Application of PID-type Predict Function of Control Algorithm in the Excitation Control

    Institute of Scientific and Technical Information of China (English)

    郭伟; 吴东; 吴青

    2012-01-01

    The adjustment of the excitation control of synchronization plays an important role in increasing stability of the power system. Low frequency oscillations will stay for a long time when the power system were stall or disturbanced, the running of the system was affected seriously. To improve the stability of the power systems running, and based on the discussion of Existing control mode and analysis of Predict function of control(FPC)algorithm and PID algorithm, the performance index of predict function of control algorithm was restructured as PID form. The derivation of PID-type predict function of control algorithm(PIDPFC)was given, and applied on the excitation control of synchronization system. Through the contrast of simulation, The influence of PIDPFC controller parameter tuning on system performance was analyzed in time domain with simulations, the PIDPFC algorithm has advantages.%同步发电机励磁控制对提高电力系统稳定性起着重要的作用.当电力系统发生故障或受到扰动时,容易出现长时间的低频率振荡,严重影响系统的稳定运行.为了提高电力系统运行的稳定性,在讨论励磁控制现有控制方式和分析预测函数控制(PFC)算法和PID算法的基础上,将预测函数控制算法的性能指标构造成PID形式,推导出改进的PID型预测函数控制算法(PIDPFC),并应用于同步发电机励磁系统控制.通过仿真研究对比,在时域内分析了PIDPFC控制器的参数选择对系统控制性能的影响,取得了预期的结果,仿真结果表明了PIDPFC算法的优点.

  11. Study of the transferred angular momentum as a function of the excitation energy in the Kr + U reaction at 35 A.MeV; Etude du moment angulaire transfere en fonction de l`energie d`excitation dans la reaction Kr + U a 35 A.MeV

    Energy Technology Data Exchange (ETDEWEB)

    Josset, M.

    1996-09-06

    The aim of this study is to measure the angular momentum transferred to the target-like product, in the Kr + U reaction at 35 A.MeV, as a function of the excitation energy. The measured neutron multiplicity, as seen by the detector ORION, was used as the basic event selection criterion. This multiplicity also allows an estimation of the excitation energy transferred to the target-like product on an event by event basis. The study of the behaviour of the projectile-like component allows one to characterize two-body mechanisms, which are associated with a large energy dissipation for less peripheral collisions. The spin transferred to the target-like component is deduced from the out-plane angular distributions of the fission fragments. The study of the angular correlation between these fission fragments confirms that the dominant mechanism is essentially a two-body process. We show that the angular momentum values obtained, as a function of the excitation energy of the target-like product, have little dependence on the time taken for the nucleus to reach the saddle point. We observe a constant increase in the target-like component`s spin, varying from 15{Dirac_h} to 60{Dirac_h}, as the excitation energy increases from roughly 8 to 400 MeV. For the higher excitation energies the spin does not increase. This behaviour reflects the vanishing binary fission mechanism at high angular momenta. (author). 81 refs.

  12. Equilibrium structure and Ti-catalyzed H-2 desorption in NaAlH4 nanoparticles from density functional theory

    DEFF Research Database (Denmark)

    Vegge, T.

    2006-01-01

    the kinetics significantly, the physical understanding remains elusive. Density functional theory is used to calculate the energy of the potential low energy surfaces of NaAlH4 to establish the equilibrium particle shape, and furthermore to determine the deposition energy of Ti/TiH2 and the substitutional......Improving the hydrogen ab- and desorption kinetics in complex hydrides is essential if these materials are to be used as reversible hydrogen storage media in the transport sector. Although reductions in particle size and the addition of titanium based compounds have been found to improve...

  13. Hydrogen dynamics in Na3AlH6: A combined density functional theory and quasielastic neutron scattering study

    DEFF Research Database (Denmark)

    Voss, Johannes; Shi, Qing; Jacobsen, Hjalte Sylvest

    2007-01-01

    alanate with TiCl3, and here we study hydrogen dynamics in doped and undoped Na3AlH6 using a combination of density functional theory calculations and quasielastic neutron scattering. The hydrogen dynamics is found to be vacancy mediated and dominated by localized jump events, whereas long-range bulk......Understanding the elusive catalytic role of titanium-based additives on the reversible hydrogenation of complex hydrides is an essential step toward developing hydrogen storage materials for the transport sector. Improved bulk diffusion of hydrogen is one of the proposed effects of doping sodium...

  14. Derivation of Process Path Functions in Machining of Al Alloy 7075

    Science.gov (United States)

    Tabei, A.; Shih, D. S.; Garmestani, H.; Liang, S. Y.

    2015-11-01

    The evolution of micro-texture below the machined surface is computationally modeled and experimentally verified. The orientation distribution functions of the grains below the surface were represented in spectral form. The microstructure descriptor coefficients were derived, and their change with respect to the change in the cutting feed rate was computationally calculated and monitored. Micro-texture experimental observations conducted by electron back-scatter diffraction technique verify the modeling outputs. Continuation of changing the process parameter was done by finite element method, and the evolution in texture was investigated by computational modeling. The process path function which correlates micro-texture evolution and cutting feed rate, was obtained by applying the principle of orientation conservation in the Euler space. As a result of the major finding of this work, i.e., derivation of process path functions, the evolution of texture as a function of the material feed rate is numerically determined without any need to texture modeling or finite element analyses.

  15. SYNTHESIS OF FUNCTIONAL MACROMOLECULE INTERMEDIATE THROUGH ACYLATION CATALYZED BY [Emim]Cl-AlCl3 IONIC LIQUID

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Acylation reaction of anthracene with oxalyl chloride in the presence of [Emim]C1-A1C13 ionic liquid has been investigated. Pure 1,2-aceanthryenedione, which is used as intermediate of functional aromatic polymer material, was obtained by recrystalling the reaction mixture with aether and was determined by GC/MS, 1HNMR and FTIR analysis. The influences of various parameters, such as the contents of AlCl3 in [Emim]C1-A1C13, the amount of acylation agent, amount of [Emim]C1-A1C13, reaction temperature and reaction time were investigated. The optimum conditions were as follows: the molar fraction of A1C13 in ionic liquid [x(AlCl3)] being 0.67 , molar ratio of ionic liquid to anthracene being 2:1 , molar ratio of oxalyl chloride to anthracene being 2:1, reaction temperature being 40℃ and reaction time being 6h. Under above conditions, the yield and selectivity of 1,2-aceanthrylenedione can reach 91.5% and 98.3% respectively. Further more, [Emim]C1-A1C13 ionic liquid, compared with metal halides such as AlCl3, was found to catalyze the reaction as a novel environmental friendly catalyst and solvent and can be reused.

  16. Wear and Corrosion Behavior of Functionally Graded Nano-SiC/2014Al Composites Produced by Powder Metallurgy

    Science.gov (United States)

    Wang, Zhi-Guo; Li, Chuan-Peng; Wang, Hui-Yuan; Zhu, Jia-Ning; Wang, Cheng; Jiang, Qi-Chuan

    2017-02-01

    Functionally graded 2014Al/SiC composites (FGMs) with varying volume fractions (1-7%) of nano-SiC particulates (n-SiCp) were fabricated by powder metallurgy. The effect of n-SiCp content on corrosion and wear behaviors was studied. The microstructures of composites were characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy. The corrosion behavior of the composites was evaluated by potentiodynamic polarization scans in 3.5 wt.% NaCl solution. Corrosion results show that corrosion current of composite layer with 3 vol.% n-SiC was much lower than that of 2014Al matrix. Mechanical properties of the composites were assessed by microhardness tests and ball-on-disk wear tests. As the applied load changed from 15 to 30 N, wear rates of the composites increased significantly and the wear mechanism transformed from mild to severe wear regime. It also shows that 3 vol.% n-SiCp/2014Al composite layer observed the lowest wear rate where adhesive and abrasive wear mechanisms played a major role. These results suggest that the n-SiCp are effective candidates for fabricating FGMs for the applications demanding a tough core and a hard, wear or corrosion resisting surface.

  17. Density functional study of structural and electronic properties of Al{sub n}@C{sub 60}

    Energy Technology Data Exchange (ETDEWEB)

    Dhiman, Shobhna, E-mail: s-dhiman@hotmail.com [Department of Applied Science, PEC, University of Technology, Chandigarh-160012 (India); Kumar, Ranjan; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2014-04-24

    Fullerene derivatives have been shown to make contributions in many types of applications. Ab initio investigation of structural and electronic properties of aluminum doped endohedral fullerene has been performed using numerical atomic orbital density functional theory. We have obtained ground state structures for Al{sub n}@C{sub 60} (n=1–10). Which shows that C{sub 60} molecule can accommodate maximum of nine aluminum atoms, for n > 9 the cage eventually break. Encapsulated large number of aluminum atoms leads to deformation of cage with diameter varies from 7.16Å to 7.95Å. Binding energy/Al atom is found to increase till n = 4 and after that it decreases with the number of Al atoms with a sudden increase for n=10 due to breakage of C{sub 60} cage and electronic affinity first increases till n=4 then it decreases up to n=9 with a sharp increase for n=10. Ionization potential also first increases and then decreases. Homo-Lumo gap decreases till n=3 with a sharp increase for n=4, after that it shows an oscillatory nature. The results obtained are consistent with available theoretical and experimental results. The ab-initio calculations were performed using SIESTA code with generalized gradient approximation (GGA)

  18. X-ray tomographic imaging of Al/SiC{sub p} functionally graded composites fabricated by centrifugal casting

    Energy Technology Data Exchange (ETDEWEB)

    Velhinho, A. E-mail: ajv@fct.unl.ptajv@engmateriais.eng.uminho.pt; Sequeira, P.D.; Martins, Rui; Vignoles, G.; Braz Fernandes, F.; Botas, J.D.; Rocha, L.A

    2003-01-01

    The present work refers to an X-ray microtomography experiment aiming at the elucidation of some aspects regarding particle distribution in SiC-particle-reinforced functionally graded aluminium composites. Precursor composites were produced by rheocasting. These were then molten and centrifugally cast to obtain the functionally graded composites. From these, cylindrical samples, around 1 mm in diameter, were extracted, which were then irradiated with a X-ray beam produced at the European Synchrotron Radiation Facility. The 3-D images were obtained in edge-detection mode. A segmentation procedure has been adapted in order to separate the pores and SiC particles from the Al matrix. Preliminary results on the particle and pore distributions are presented.

  19. X-ray tomographic imaging of Al/SiC p functionally graded composites fabricated by centrifugal casting

    Science.gov (United States)

    Velhinho, A.; Sequeira, P. D.; Martins, Rui; Vignoles, G.; Braz Fernandes, F.; Botas, J. D.; Rocha, L. A.

    2003-01-01

    The present work refers to an X-ray microtomography experiment aiming at the elucidation of some aspects regarding particle distribution in SiC-particle-reinforced functionally graded aluminium composites. Precursor composites were produced by rheocasting. These were then molten and centrifugally cast to obtain the functionally graded composites. From these, cylindrical samples, around 1 mm in diameter, were extracted, which were then irradiated with a X-ray beam produced at the European Synchrotron Radiation Facility. The 3-D images were obtained in edge-detection mode. A segmentation procedure has been adapted in order to separate the pores and SiC particles from the Al matrix. Preliminary results on the particle and pore distributions are presented.

  20. Fabrication and Characterization of Functionally Graded Al/SiCp Composites Produced by Remelting and Sedimentation Process

    Science.gov (United States)

    Pourmajidian, Maedeh; Akhlaghi, Farshad

    2013-12-01

    A new process termed here as remelting and sedimentation (RAS) was developed to produce functionally graded Al/SiC composites with a smooth concentration gradient of SiC particles along the height of samples, as opposed to a step change. For this purpose, first settling velocities of different-sized SiC particles in aluminum A356 melt were measured, and the results exhibited a reasonably good agreement with those predicted via the modified Stokes law. Then slices of particulate Al/SiC composites with different SiC contents of 5, 10, 15, and 20 vol.% were stacked in a cast iron mold and heated at 650 °C resulting in remelting and unification of the different composite parts. Considering the preliminary settling experiments, the composite slurry was held at this temperature for three different times to investigate the optimum holding time for obtaining a smooth gradient of SiC concentration along the height of the sample. After quenching, the samples were sectioned and subjected to metallographic studies and hardness measurements. The results confirmed that holding the melt for 60 s provides sufficient settling and redistribution of SiC particles and results in successful production of a functionally graded material.

  1. Description of excited states in [Re(Imidazole)(CO)3 (Phen)](+) including solvent and spin-orbit coupling effects: Density functional theory versus multiconfigurational wavefunction approach.

    Science.gov (United States)

    Fumanal, Maria; Daniel, Chantal

    2016-10-15

    The low-lying electronic excited states of [Re(imidazole)(CO)3 (phen)](+) (phen = 1,10-phenanthroline) ranging between 420 nm and 330 nm have been calculated by means of relativistic spin-orbit time-dependent density functional theory (TD-DFT) and wavefunction approaches (state-average-CASSCF/CASPT2). A direct comparison between the theoretical absorption spectra obtained with different methods including SOC and solvent corrections for water points to the difficulties at describing on the same footing the bands generated by metal-to-ligand charge transfer (MLCT), intraligand (IL) transition, and ligand-to-Ligand- charge transfer (LLCT). While TD-DFT and three-roots-state-average CASSCF (10,10) reproduce rather well the lowest broad MLCT band observed in the experimental spectrum between 420 nm and 330 nm, more flexible wavefunctions enlarged either by the number of roots or by the number of active orbitals and electrons destabilize the MLCT states by introducing IL and LLCT character in the lowest part of the absorption spectrum. © 2016 Wiley Periodicals, Inc.

  2. Acupuncture Relieves the Excessive Excitation of Hypothalamic-Pituitary-Adrenal Cortex Axis Function and Correlates with the Regulatory Mechanism of GR, CRH, and ACTHR

    Directory of Open Access Journals (Sweden)

    Shao-Jun Wang

    2014-01-01

    Full Text Available It had been indicated in the previous studies that acupuncture relieved the excessive excitation of hypothalamic-pituitary-adrenal cortex axis (HPAA function induced by stress stimulation. But the changes in glucocorticoid receptor (GR induced by acupuncture have not been detected clearly. The objective of the study was to observe the impacts of acupuncture on the protein expressions of corticotrophin releasing hormone (CRH, adrenocorticotropic hormone receptor (ACTHR, and GR under the physiological and stress states. The results showed that under the stress state, acupuncture upregulated the protein expression of GR in the hippocampus, hypothalamic paraventricular nucleus (PVN, and pituitary gland, downregulated the protein expression of GR in the adrenal cortex, and obviously reduced the protein expressions of CRH and ACTHR. Under the physiological state, acupuncture promoted GR protein expression in the hippocampus and CRH protein expression in the hippocampus and PVN. The results explained that acupuncture regulated the stress reaction via promoting the combination of glucocorticoids (GC with GR, and GR protein expression. The increase of GR protein expression induced feedback inhibition on the overexpression of CRH and ACTHR, likely decreased GC level, and caused the reduction of GR protein expression in the adrenal cortex.

  3. Reversed Effects of Intermittent Theta Burst Stimulation following Motor Training That Vary as a Function of Training-Induced Changes in Corticospinal Excitability

    Directory of Open Access Journals (Sweden)

    Tino Stöckel

    2015-01-01

    Full Text Available Intermittent theta burst stimulation (iTBS has the potential to enhance corticospinal excitability (CSE and subsequent motor learning. However, the effects of iTBS following motor learning are unknown. The purpose of the present study was to explore the effect of iTBS on CSE and performance following motor learning. Therefore twenty-four healthy participants practiced a ballistic motor task for a total of 150 movements. iTBS was subsequently applied to the trained motor cortex (STIM group or the vertex (SHAM group. Performance and CSE were assessed before motor learning and before and after iTBS. Training significantly increased performance and CSE in both groups. In STIM group participants, subsequent iTBS significantly reduced motor performance with smaller reductions in CSE. CSE changes as a result of motor learning were negatively correlated with both the CSE changes and performance changes as a result of iTBS. No significant effects of iTBS were found for SHAM group participants. We conclude that iTBS has the potential to degrade prior motor learning as a function of training-induced CSE changes. That means the expected LTP-like effects of iTBS are reversed following motor learning.

  4. Acupuncture Relieves the Excessive Excitation of Hypothalamic-Pituitary-Adrenal Cortex Axis Function and Correlates with the Regulatory Mechanism of GR, CRH, and ACTHR.

    Science.gov (United States)

    Wang, Shao-Jun; Zhang, Jiao-Jiao; Qie, Li-Li

    2014-01-01

    It had been indicated in the previous studies that acupuncture relieved the excessive excitation of hypothalamic-pituitary-adrenal cortex axis (HPAA) function induced by stress stimulation. But the changes in glucocorticoid receptor (GR) induced by acupuncture have not been detected clearly. The objective of the study was to observe the impacts of acupuncture on the protein expressions of corticotrophin releasing hormone (CRH), adrenocorticotropic hormone receptor (ACTHR), and GR under the physiological and stress states. The results showed that under the stress state, acupuncture upregulated the protein expression of GR in the hippocampus, hypothalamic paraventricular nucleus (PVN), and pituitary gland, downregulated the protein expression of GR in the adrenal cortex, and obviously reduced the protein expressions of CRH and ACTHR. Under the physiological state, acupuncture promoted GR protein expression in the hippocampus and CRH protein expression in the hippocampus and PVN. The results explained that acupuncture regulated the stress reaction via promoting the combination of glucocorticoids (GC) with GR, and GR protein expression. The increase of GR protein expression induced feedback inhibition on the overexpression of CRH and ACTHR, likely decreased GC level, and caused the reduction of GR protein expression in the adrenal cortex.

  5. The structure of the hydrated electron. Part 2. A mixed quantum classical molecular dynamics - embedded cluster density functional theory: single-excitation configuration interaction study

    CERN Document Server

    Shkrob, I A; Larsen, R E; Schwartz, B J; Glover, William J.; Larsen, Ross E.; Schwartz, Benjamin J.; Shkrob, Ilya A.

    2006-01-01

    Adiabatic mixed quantum/classical molecular dynamics simulations were used to generate snapshots of the hydrated electron (e-) in liquid water at 300 K. Water cluster anions that include two complete solvation shells centered on the e- were extracted from these simulations and embedded in a matrix of fractional point charges designed to represent the rest of the solvent. Density functional theory and single-excitation configuration interaction methods were then applied to these embedded clusters. The salient feature of these hybrid calculations is significant transfer (ca. 0.18) of the excess electron's charge density into the O 2p orbitals in OH groups forming the solvation cavity. We used the results of these calculations to examine the structure of the molecular orbitals, the density of states, the absorption spectra in the visible and ultraviolet, the hyperfine coupling (hfc) tensors, and the IR and Raman spectra of the e-. The calculated hfc tensors were used to compute the EPR and ESEEM spectra for the ...

  6. Excitation function of the alpha particle induced nuclear reactions on enriched 116Cd, production of the theranostic isotope 117mSn

    Science.gov (United States)

    Ditrói, F.; Takács, S.; Haba, H.; Komori, Y.; Aikawa, M.; Szűcs, Z.; Saito, M.

    2016-10-01

    117mSn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of 116Cd metal onto high purity 12 μm thick Cu backing. The average deposited thickness was 21.9 μm. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil catcher of the reaction products from the cadmium layer. The activities of the irradiated foils were measured with HPGe detector for gamma-ray spectrometry and cross section values were determined. As a result excitation functions for the formation of 117mSn, 117m,gIn, 116mIn, 115mIn and 115m,gCd from enriched 116Cd were deduced and compared with the available literature data and with the results of the nuclear reaction model code calculations EMPIRE 3.2 and TALYS 1.8. Yield curves were also deduced for the measured nuclear reactions and compared with the literature.

  7. Excitation function of the alpha particle induced nuclear reactions on enriched $^{116}$Cd, production of the theranostic isotope $^{117m}$Sn

    CERN Document Server

    Ditrói, F; Haba, H; Komori, Y; Aikawa, M; Szűcs, Z; Saito, M

    2016-01-01

    $^{117m}$Sn is one of the radioisotopes can be beneficially produced through alpha particle irradiation. The targets were prepared by deposition of $^{116}$Cd metal onto high purity 12 $\\mu$m thick Cu backing. The average deposited thickness was 21.9 $\\mu$m. The beam energy was thoroughly measured by Time of Flight (TOF) methods and proved to be 51.2 MeV. For the experiment the well-established stacked foil technique was used. In addition to the Cd targets, Ti foils were also inserted into the stacks for energy and intensity monitoring. The Cu backings were also used for monitoring and as recoil catcher of the reaction products from the cadmium layer. The activities of the irradiated foils were measured with HPGe detector for gamma-ray spectrometry and cross section values were determined. As a result excitation functions for the formation of $^{117m}$Sn, $^{117m,g}$In, $^{116m}$In, $^{115m}$In and $^{115m,g}$Cd from enriched $^{116}$Cd were deduced and compared with the available literature data and with the...

  8. Validation of the German version of the extended ALS functional rating scale as a patient-reported outcome measure.

    Science.gov (United States)

    Abdulla, Susanne; Vielhaber, Stefan; Körner, Sonja; Machts, Judith; Heinze, Hans-Jochen; Dengler, Reinhard; Petri, Susanne

    2013-09-01

    The revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) is a well-established rating instrument to assess the functional status of ALS patients. A recent innovation was the addition of three further items designed to improve its sensitivity at lower levels of physical function (ALSFRS-Extension, ALSFRS-EX). Neither the ALSFRS-R nor the ALSFRS-EX has been validated in German yet. The aim of the present study was the validation of the German version of a self-administered form of the ALSFRS-EX. Seventy-six patients participated in the study. Psychometric analysis included reliability assessment and factorial analysis. To evaluate convergent validity, correlations between ALSFRS-EX items and the MRC score, spasticity, tongue movement, pulmonary function, ALSAQ-40 and Borg dyspnoea scales (upright and supine) were performed. Internal consistency as measured by Cronbach's alpha (total scale 0.868, subscales 0.690-0.938) and corrected item to total correlations (all above 0.50) was high. Test-retest reliability assessed by Spearman's rho (0.882-0.972) and Cohen's Kappa (0.63-0.92) was also high. Principal component analysis with varimax rotation yielded a four-factor solution accounting for approximately 79% of the variance. Clinical parameters were strongly correlated with respective items and subscores of the ALSFRS-EX (muscle strength 0.568-0.833 p scale including high internal consistency and test-retest reliability as well as excellent convergent validity.

  9. Modulation transfer function characteristic of uniform-doping transmission-mode GaAs/GaAlAs photocathode

    Institute of Scientific and Technical Information of China (English)

    Ren Ling; Chang Ben-Kang

    2011-01-01

    The resolution characteristic can be obtained by the modulation transfer function(MTF)of a GaAs/GaAlAs photocathode.After establishing the theoretical model of GaAs(100)-oriented atomic configuration and the formula for the ionized impurity scattering of the non-equilibrium carriers,this paper calculates the trajectories of photoelectrons in a photocathode.Thus the distribution of photoelectron spots on the emit-face is obtained,which is namely the point spread function.The MTF is obtained by Fourier transfer of the line spread function obtained from the point spread function.The MTF obtained from these calculations is shown to depend heavily on the electron diffusion length,and enhanced considerably by decreasing the electron diffusion length and increasing the doping concentration.Furthermore,the resolution is enhanced considerably by increasing the active-layer thickness,especially at high spatial frequencies.The best spatial resolution is 860 lp/mm,for the GaAs photocathode of doping concentration 1×1019cm-3,electron diffusion length 3.6 μm and the active-layer thickness 2 μm,under the 633-nm light irradiated. This research will contribute to the future improvement of the cathode's resolution for preparing a high performance GaAs photocathode,and improve the resolution of a low light level image intensifier.

  10. Prediction of forming limit curve (FLC) for Al-Li alloy 2198-T3 sheet using different yield functions

    Institute of Scientific and Technical Information of China (English)

    Li Xiaoqiang; Song Nan; Guo Guiqiang; Sun Zhonggang

    2013-01-01

    The Forming Limit Curve (FLC) of the third generation aluminum-lithium (Al-Li) alloy 2198-T3 is measured by conducting a hemispherical dome test with specimens of different widths. The theoretical prediction of the FLC of 2198-T3 is based on the M-K theory utilizing respectively the von Mises, Hill’48, Hosford and Barlat 89 yield functions, and the different predicted curves due to different yield functions are compared with the experimentally measured FLC of 2198-T3. The results show that though there are differences among the four predicted curves, yet they all agree well with the experimentally measured curve. In the area near the planar strain state, the predicted curves and experimentally measured curve are very close. The predicted curve based on the Hosford yield function is more accurate under the tension-compression strain states described in the left part of the FLC, while the accuracy is better for the predicted curve based on Hill’48 yield function under the tension-tension strain states shown in the right part.

  11. Simulation on function mechanism of Tl(Al2CuLi) precipitate in localized corrosion of Al-Cu-Li alloys

    Institute of Scientific and Technical Information of China (English)

    LI Jin-feng; ZHENG Zi-qiao; REN Wen-da; CHEN Wen-jing; ZHAO Xu-shan; LI Shi-chen

    2006-01-01

    To clarify the corrosion mechanism associated with the precipitate of T1(Al2CuLi) in Al-Li alloys, the simulated bulk precipitate of T1 was fabricated through melting and casting. Its electrochemical behavior and coupling behavior with a(Al) in 3.5%NaCl solution were investigated. Meanwhile, the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed. The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1. At the beginning, the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface. However,during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Li and the enrichment of Cu. As a result, the corroded T1 becomes cathodic to the alloy base at a later stage, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery. It is suggested that the localized corrosion associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.

  12. Cortical excitability differences between flexor pollicis longus and APB.

    Science.gov (United States)

    Bae, Jong Seok; Menon, Parvathi; Mioshi, Eneida; Kiernan, Matthew C; Vucic, Steve

    2013-04-29

    Although abductor pollicis brevis (APB) and flexor pollicis longus (FPL) share a common peripheral nerve supply, these muscles subserve different functions and may be differently affected in neurodegenerative disease such as amyotrophic lateral sclerosis (ALS). As a consequence, differences in cortical excitability may potentially develop in relation to these functional differences. Cortical excitability was assessed using the threshold tracking transcranial magnetic stimulation (TMS) technique in 15 healthy controls with motor responses recorded over the APB and FPL using surface electrode recordings. Short-interval intracortical inhibition (SICI) was significantly reduced from the FPL compared to APB (SICIFPL 6.9±1.8%; SICIAPB 10.7±1.4%, P<0.01). In addition, the FPL motor evoked potential amplitude (MEPFPL 14.7±2.3%; MEPAPB 21.7±3.9%; P<0.01) and cortical silent period duration (CSPFPL 174.7±6.7ms; CSPAPB 205.4±3.9ms, P<0.01) were significantly smaller. The findings in the present study indicate that cortical inhibition and corticomotoneuronal output is reduced when recording over the FPL. The differences in cortical excitability may develop as a consequence of varied function and could potentially explain the dissociated muscle atrophy evident in ALS.

  13. Density functional theory assessment of molecular structures and energies of neutral and anionic Al(n) (n = 2-10) clusters.

    Science.gov (United States)

    Paranthaman, Selvarengan; Hong, Kiryong; Kim, Joonghan; Kim, Dong Eon; Kim, Tae Kyu

    2013-09-26

    We report the results of a benchmarking study on hybrid, hybrid-meta, long-range-corrected, meta-generalized gradient approximation (meta-GGA), and GGA density functional theory (DFT) methods for aluminum (Al) clusters. A range of DFT functionals, such as B3LYP, B1B95, PBE0, mPW1PW91, M06, M06-2X, ωB97X, ωB97XD, TPSSh, BLYP, PBE, mPWPW91, M06-L, and TPSS, have been used to optimize the molecular structures and calculate the vibrational frequencies and four energetic parameters for neutral and anionic Al(n) (n = 2-10) clusters. The performances of these functionals are assessed systematically by calculating the vertical ionization energy for neutral Al clusters and the vertical electron detachment energy for anionic Al clusters, along with the cohesive energy and dissociation energy. The results are compared with the available experimental and high-level ab initio calculated results. The calculated results showed that the PBE0 and mPW1PW91 functionals generally provide better results than the other functionals studied. TPSS can be a good choice for the calculations of very large Al clusters. On the other hand, the B3LYP, BLYP, and M06-L functionals are in poor agreement with the available experimental and theoretical results. The calculated results suggest that the hybrid DFT functionals like B3LYP do not always provide better performance than GGA functionals.

  14. Decentralized Excitation Control of Multi-machine Multi-load Power Systems Using Hamiltonian Function Method%基于Hanmiton函数方法的多机多负荷电力系统分散励磁控制

    Institute of Scientific and Technical Information of China (English)

    刘艳红; 李春文; 王玉振

    2009-01-01

    Using the Hamiltonian function method, we investigate the excitation control of multi-machine multi-load power systems presented by nonlinear differential algebraic equations. First, the power system is reformulated as a novel Hamiltonian realization structure via pre-feedback state control. Then, based on the dissipative Hamiltonian realization of the system, a decentralized nonlinear excitation control scheme is constructed. The stability of the closed loop system is analyzed as well. The proposed strategy takes advantage of the intrinsic properties especially including the internal power balance of the power system. Simulation illustrates the effectiveness of the control strategy.

  15. The Relationship between Language Functions and Character Types in Noon val-Ghalam by Jalal Al Ahmad

    Directory of Open Access Journals (Sweden)

    Sayyed Ahmad Parsa

    2013-11-01

    Full Text Available Abstract Making harmony among language functions of story characters with their character types is one of the characteristics and advantages of modern and successful story writing. In traditional fictional literature in Iran (prose and verse, this point is not considered important and story characters, generally, speak in the voice of narrator or writer since there is the narrators statement on their speech, they are not the representative of their class and character type. Not paying attention to this subject, causes disorder in either making supposition of reality or personifying, which are both important principals of story telling. This study views from this point the story of Noon val-Ghalam of Jalal Al Ahmad who is a contemporary writer. The methodology is qualitative, and data collection is based on content–analysis and document- analysis. As Al Ahmad was one of the Iranian contemporary writers and was familiar with western and Iranian writers, it is expected that the language and way of describing story characters he made, be based on their social classes. But this study, by stating different proofs, shows that this writer ignores the relationship necessary for language functions and character type among characters in the story and because of the imposition of his knowledge, statement and political and social view, the independence of the protagonists in his story is not well-considered.  The inflection of political and social thoughts of each writer among his works, is not a shortfall by itself, but representing of speeches in protagonists, in the way which is not in harmony with their characters, underestimates them as an instrument for specific social and political representatives. This not only displays the character like a personified ideas, but also distructs processing of fictional dialogue as an important element in storytelling . Since in each language people from different social groups, use almost the same vocabularies that

  16. Excited hexagon Wilson loops for strongly coupled N=4 SYM

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Kotanski, J. [Hamburg Univ. (Germany). II. Inst. fuer Theoretische Physik; Schomerus, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); British Columbia Univ., Vancouver, BC (Canada). Dept. of Physics and Astronomy

    2010-10-15

    This work is devoted to the six-gluon scattering amplitude in strongly coupled N=4 supersymmetric Yang-Mills theory. At weak coupling, an appropriate high energy limit of the so-called remainder function, i.e. of the deviation from the BDS formula, may be understood in terms of the lowest eigenvalue of the BFKL hamiltonian. According to Alday et al., amplitudes in the strongly coupled theory can be constructed through an auxiliary 1-dimensional quantum system. We argue that certain excitations of this quantum system determine the Regge limit of the remainder function at strong coupling and we compute its precise value. (orig.)

  17. Theoretical research relating to excitation spectrum of furan. Application of integral direct coupled cluster linear response (direct CCLR) method; Furan no reiki supekutoru ni kansuru ronriteki kenkyu. Integral-direct Coupled Cluster Linear Response (direct CCLR) ho no tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Shigemitsu, Yasuhiro. [Nagasaki Industrial Technology Center, Nagasaki (Japan)

    1999-07-01

    heoretical researches relating to excitation spectrum of furan have been carried out for many years, and they reveal the problems that should be solved in order to predict highly reliable excitation energy. In general, it is difficult to uniformly obtain highly reliable calculation results for all excitation states since different excitation states show different electronic correlative effects. Means for obtaining the electron states in ground state and excited state and calculating the energy difference thereof is the mainstream of the theoretical calculation of the excitation energy. CASSCF/CASPT 2 developed by Roos et al. is a typical method excellent in quantitative description. Recently, the comparison between direct CCLR and CASSCF/CASPT 2 as examples for calculating the excitation spectrum of furan was carried out by using the same ground function. For Rydberg excitation, CC3, CAS, CASPT 2 show good agreement with each other. (NEDO)

  18. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation

    Indian Academy of Sciences (India)

    G A Adebayo; O Akinlade; L A Hussain

    2005-02-01

    The structures and autocorrelation functions of Al and Mg in the liquid state are investigated through the pair distribution function (), the diffusion coefficients as well as the shear viscosity via the Green{Kubo and Einstein relations. From the structure and the Enskog relation we determined the frequency of collisions of atoms in the first shell of () in the systems. We also discovered that the packing fraction of Lennard-Jones liquids should be approximately half the reduced density value. This approximation is accurate to within 99%. The temperature dependence of the pair distribution function and the atomic mean square displacement are investigated by performing simulations at various experimental temperatures and corresponding densities. The structures of the systems are affected by temperature via movements of atoms in the first minimum of (). The Lennard-Jones model shows that density dependence of the shear viscosity is in agreement with what is expected of simple liquids in the range of investigated temperatures and densities. In the gas limit, the Stoke-Einstein relation = B/2 is grossly overestimated by Lennard-Jones model. This could not be attributed to defficiencies in the model, as other investigators using first principle method could not obtain the gas limit of the Stoke-Einstein relation.

  19. Electronic structure and optical properties of CdS{sub x}Se{sub 1−x} solid solution nanostructures from X-ray absorption near edge structure, X-ray excited optical luminescence, and density functional theory investigations

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, M. W. [DESY (Deutsches Elektronen-Synchrotron), FS-PEX, Notkestrasse 85, 22607 Hamburg (Germany); Yiu, Y. M., E-mail: yyiu@uwo.ca; Sham, T. K. [Department of Chemistry, University of Western Ontario, London, ON N6A5B7 (Canada); Ward, M. J. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Liu, L. [Institute of Functional Nano and Soft Materials (FUNSOM) and Soochow University-Western University Center for Synchrotron Radiation Research, Soochow University, Suzhou, Jiangsu, 215123 (China); Hu, Y. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N2V3 (Canada); Zapien, J. A. [Center Of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Science, City University of Hong Kong, Hong Kong SAR (China); Liu, Yingkai [Institute of Physics and Electronic Information, Yunnan Normal University, Kunming, Yunnan, 650500 (China)

    2014-11-21

    The electronic structure and optical properties of a series of iso-electronic and iso-structural CdS{sub x}Se{sub 1−x} solid solution nanostructures have been investigated using X-ray absorption near edge structure, extended X-ray absorption fine structure, and X-ray excited optical luminescence at various absorption edges of Cd, S, and Se. It is found that the system exhibits compositions, with variable local structure in-between that of CdS and CdSe accompanied by tunable optical band gap between that of CdS and CdSe. Theoretical calculation using density functional theory has been carried out to elucidate the observations. It is also found that luminescence induced by X-ray excitation shows new optical channels not observed previously with laser excitation. The implications of these observations are discussed.

  20. Functional network overlap as revealed by fMRI using sICA and its potential relationships with functional heterogeneity, balanced excitation and inhibition, and sparseness of neuron activity.

    Science.gov (United States)

    Xu, Jiansong; Calhoun, Vince D; Worhunsky, Patrick D; Xiang, Hui; Li, Jian; Wall, John T; Pearlson, Godfrey D; Potenza, Marc N

    2015-01-01

    Functional magnetic resonance imaging (fMRI) studies traditionally use general linear model-based analysis (GLM-BA) and regularly report task-related activation, deactivation, or no change in activation in separate brain regions. However, several recent fMRI studies using spatial independent component analysis (sICA) find extensive overlap of functional networks (FNs), each exhibiting different task-related modulation (e.g., activation vs. deactivation), different from the dominant findings of GLM-BA. This study used sICA to assess overlap of FNs extracted from four datasets, each related to a different cognitive task. FNs extracted from each dataset overlapped with each other extensively across most or all brain regions and showed task-related concurrent increases, decreases, or no changes in activity. These findings indicate that neural substrates showing task-related concurrent but different modulations in activity intermix with each other and distribute across most of the brain. Furthermore, spatial correlation analyses found that most FNs were highly consistent in spatial patterns across different datasets. This finding indicates that these FNs probably reflect large-scale patterns of task-related brain activity. We hypothesize that FN overlaps as revealed by sICA might relate to functional heterogeneity, balanced excitation and inhibition, and population sparseness of neuron activity, three fundamental properties of the brain. These possibilities deserve further investigation.

  1. Calculation of the total electron excitation cross section in the Born approximation using Slater wave functions for the Li (2s yields 2p), Li (2s yields 3p), Na (3s yields 4p), Mg (3p yields 4s), Ca (4s yields 4p) and K (4s yields 4p) excitations. M.S. Thesis

    Science.gov (United States)

    Simsic, P. L.

    1974-01-01

    Excitation of neutral atoms by inelastic scattering of incident electrons in gaseous nebulae were investigated using Slater Wave functions to describe the initial and final states of the atom. Total cross sections using the Born Approximation are calculated for: Li(2s yields 2p), Na(3s yields 4p), k(4s yields 4p). The intensity of emitted radiation from gaseous nebulae is also calculated, and Maxwell distribution is employed to average the kinetic energy of electrons.

  2. Comment on "Nature of the Seismic Lithosphere-Asthenosphere Boundary within Normal Oceanic Mantle from High-Resolution Receiver Functions" by Olugboji et al.

    Science.gov (United States)

    Kawakatsu, Hitoshi; Abe, Yuki

    2016-08-01

    The significance of sediment reverberations on receiver functions of broadband OBS data is discussed. In particular, the data analyzed by Olugboji et al. recently in this journal show such effects which need to be carefully modeled. We also suggest that the LQ-coordinate rotation for the receiver function analysis should be avoided for OBS data.

  3. The structure of the hydrated electron. Part 2. A mixed quantum/classical molecular dynamics embedded cluster density functional theory: single-excitation configuration interaction study.

    Science.gov (United States)

    Shkrob, Ilya A; Glover, William J; Larsen, Ross E; Schwartz, Benjamin J

    2007-06-21

    Adiabatic mixed quantum/classical (MQC) molecular dynamics (MD) simulations were used to generate snapshots of the hydrated electron in liquid water at 300 K. Water cluster anions that include two complete solvation shells centered on the hydrated electron were extracted from the MQC MD simulations and embedded in a roughly 18 Ax18 Ax18 A matrix of fractional point charges designed to represent the rest of the solvent. Density functional theory (DFT) with the Becke-Lee-Yang-Parr functional and single-excitation configuration interaction (CIS) methods were then applied to these embedded clusters. The salient feature of these hybrid DFT(CIS)/MQC MD calculations is significant transfer (approximately 18%) of the excess electron's charge density into the 2p orbitals of oxygen atoms in OH groups forming the solvation cavity. We used the results of these calculations to examine the structure of the singly occupied and the lower unoccupied molecular orbitals, the density of states, the absorption spectra in the visible and ultraviolet, the hyperfine coupling (hfcc) tensors, and the infrared (IR) and Raman spectra of these embedded water cluster anions. The calculated hfcc tensors were used to compute electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectra for the hydrated electron that compared favorably to the experimental spectra of trapped electrons in alkaline ice. The calculated vibrational spectra of the hydrated electron are consistent with the red-shifted bending and stretching frequencies observed in resonance Raman experiments. In addition to reproducing the visible/near IR absorption spectrum, the hybrid DFT model also accounts for the hydrated electron's 190-nm absorption band in the ultraviolet. Thus, our study suggests that to explain several important experimentally observed properties of the hydrated electron, many-electron effects must be accounted for: one-electron models that do not allow for mixing of the excess

  4. The structure of the hydrated electron. Part 2. A mixed quantum/classical molecular dynamics embedded cluster density functional theory : single-excitation configuration interaction study.

    Energy Technology Data Exchange (ETDEWEB)

    Shkrob, I. A.; Glover, W. J.; Larsen, R. E.; Schwartz, B. J.; Chemistry; Univ. of California at Los Angeles

    2007-06-21

    Adiabatic mixed quantum/classical (MQC) molecular dynamics (MD) simulations were used to generate snapshots of the hydrated electron in liquid water at 300 K. Water cluster anions that include two complete solvation shells centered on the hydrated electron were extracted from the MQC MD simulations and embedded in a roughly 18 Angstrom x 18 Angstrom x 18 Angstrom matrix of fractional point charges designed to represent the rest of the solvent. Density functional theory (DFT) with the Becke-Lee-Yang-Parr functional and single-excitation configuration interaction (CIS) methods were then applied to these embedded clusters. The salient feature of these hybrid DFT(CIS)/MQC MD calculations is significant transfer ({approx}18%) of the excess electron's charge density into the 2p orbitals of oxygen atoms in OH groups forming the solvation cavity. We used the results of these calculations to examine the structure of the singly occupied and the lower unoccupied molecular orbitals, the density of states, the absorption spectra in the visible and ultraviolet, the hyperfine coupling (hfcc) tensors, and the infrared (IR) and Raman spectra of these embedded water cluster anions. The calculated hfcc tensors were used to compute electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectra for the hydrated electron that compared favorably to the experimental spectra of trapped electrons in alkaline ice. The calculated vibrational spectra of the hydrated electron are consistent with the red-shifted bending and stretching frequencies observed in resonance Raman experiments. In addition to reproducing the visible/near IR absorption spectrum, the hybrid DFT model also accounts for the hydrated electron's 190-nm absorption band in the ultraviolet. Thus, our study suggests that to explain several important experimentally observed properties of the hydrated electron, many-electron effects must be accounted for: one-electron models that do not

  5. RESONANT CAVITY EXCITATION SYSTEM

    Science.gov (United States)

    Baker, W.R.; Kerns, Q.A.; Riedel, J.

    1959-01-13

    An apparatus is presented for exciting a cavity resonator with a minimum of difficulty and, more specifically describes a sub-exciter and an amplifier type pre-exciter for the high-frequency cxcitation of large cavities. Instead of applying full voltage to the main oscillator, a sub-excitation voltage is initially used to establish a base level of oscillation in the cavity. A portion of the cavity encrgy is coupled to the input of the pre-exciter where it is amplified and fed back into the cavity when the pre-exciter is energized. After the voltage in the cavity resonator has reached maximum value under excitation by the pre-exciter, full voltage is applied to the oscillator and the pre-exciter is tunned off. The cavity is then excited to the maximum high voltage value of radio frequency by the oscillator.

  6. Electronic structures of AlMoO(y)(-) (y = 1-4) determined by photoelectron spectroscopy and density functional theory calculations.

    Science.gov (United States)

    Waller, Sarah E; Mann, Jennifer E; Hossain, Ekram; Troyer, Mary; Jarrold, Caroline C

    2012-07-14

    Vibrationally-resolved photoelectron spectra of AlMoO(y)(-) (y = 1-4) are presented and analyzed in conjunction with density functional theory computational results. The structures determined for the AlMoO(y) anion and neutral clusters suggest ionic bonding between Al(+) and a MoO(y)(-) or MoO(y)(-2) moiety, and point to the relative stability of Mo=O versus Al=O bonds. The highest occupied and partially occupied orbitals in the anions and neutrals can be described as Mo atomic-like orbitals, so while the Mo is in a higher oxidation state than Al, the most energetically accessible electrons are localized on the molybdenum center.

  7. Probabilistic excitation of plasma transitions

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Sanae; Toda, Shinichiro; Yagi, Masatoshi [Kyushu Univ., Kasuga, Fukuoka (Japan). Research Inst. for Applied Mechanics; Itoh, Kimitaka; Fukuyama, Atsushi

    1998-12-01

    Statistical property of an excitation of plasma transition is analyzed, which takes place in a strongly turbulent state. Transition characteristics which have been studied in a deterministic picture are re-examined. Model equations of transition, with a hysteresis nature in flux-gradient relation in the presence of strong self-noise, are solved and the dynamics of plasma gradient and turbulent-driven flux is studied. The excitation probability is shown to be fairly large well below the conventional critical condition. Probability distribution function, as a function of the gradient, for an onset of the transition is obtained both for power law noise. (author)

  8. The Influence of Al2O3 Powder Morphology on the Properties of Cu-Al2O3 Composites Designed for Functionally Graded Materials (FGM)

    Science.gov (United States)

    Strojny-Nędza, Agata; Pietrzak, Katarzyna; Węglewski, Witold

    2016-08-01

    In order to meet the requirements of an increased efficiency applying to modern devices and in more general terms science and technology, it is necessary to develop new materials. Combining various types of materials (such as metals and ceramics) and developing composite materials seem to be suitable solutions. One of the most interesting materials includes Cu-Al2O3 composite and gradient materials (FGMs). Due to their potential properties, copper-alumina composites could be used in aerospace industry as rocket thrusters and components in aircraft engines. The main challenge posed by copper matrix composites reinforced by aluminum oxide particles is obtaining the uniform structure with no residual porosity (existing within the area of the ceramic phase). In the present paper, Cu-Al2O3 composites (also in a gradient form) with 1, 3, and 5 vol.% of aluminum oxide were fabricated by the hot pressing and spark plasma sintering methods. Two forms of aluminum oxide (αAl2O3 powder and electrocorundum) were used as a reinforcement. Microstructural investigations revealed that near fully dense materials with low porosity and a clear interface between the metal matrix and ceramics were obtained in the case of the SPS method. In this paper, the properties (mechanical, thermal, and tribological) of composite materials were also collected and compared. Technological tests were preceded by finite element method analyses of thermal stresses generated in the gradient structure, and additionally, the role of porosity in the formation process of composite properties was modeled. Based on the said modeling, technological conditions for obtaining FGMs were proposed.

  9. Microstructure and Resisting Thermal Shock Behaviors of TiC-Al2O3/Fe Functionally Graded MaterialsPrepared by SHS/PHIP

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The microstructure and composition of TiC-Al2O3/Fe functionally graded materials (FGM) prepared by self-propagating high temperature synthesis and pseudo-hot isostatic pressing (SHS/PHIP) were studied, and the resisting thermal shock behaviors were analyzed. The results show that TiC-Al2O3/Fe FGM has graded composition distribution. No cross-section crack through the layers was found in the tests of thermal shock and fatigue.

  10. Differentiation of control and ALS mutant human iPSCs into functional skeletal muscle cells, a tool for the study of neuromuscolar diseases

    Directory of Open Access Journals (Sweden)

    Jessica Lenzi

    2016-07-01

    Full Text Available Amyotrophic Lateral Sclerosis (ALS is a severe and fatal neurodegenerative disease characterized by progressive loss of motoneurons, muscle atrophy and paralysis. Recent evidence suggests that ALS should be considered as a multi-systemic disease, in which several cell types contribute to motoneuron degeneration. In this view, mutations in ALS linked genes in other neural and non-neural cell types may exert non-cell autonomous effects on motoneuron survival and function. Induced Pluripotent Stem Cells (iPSCs have been recently derived from several patients with ALS mutations and it has been shown that they can generate motoneurons in vitro, providing a valuable tool to study ALS. However, the potential of iPSCs could be further valorized by generating other cell types that may be relevant to the pathology. In this paper, by taking advantage of a novel inducible system for MyoD expression, we show that both control iPSCs and iPSCs carrying mutations in ALS genes can generate skeletal muscle cells. We provide evidence that both control and mutant iPSC-derived myotubes are functionally active. This in vitro system will be instrumental to dissect the molecular and cellular pathways impairing the complex motoneuron microenvironment in ALS.

  11. New measurements and evaluation of excitation functions for (p,xn), (p,pxn) and (p,2pxn) reactions on {sup 133}Cs up to 70 MeV proton energy

    Energy Technology Data Exchange (ETDEWEB)

    Tarkanyi, F. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen, Bem ter 18/c (Hungary); Hermanne, A. [Vrije Universiteit Brussel (VUB), 1090 Brussels (Belgium); Takacs, S.; Ditroi, F. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen, Bem ter 18/c (Hungary); Kiraly, B. [Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), 4026 Debrecen, Bem ter 18/c (Hungary)], E-mail: kiralyb@atomki.hu; Yamazaki, H.; Baba, M.; Mohammadi, A. [Cyclotron and Radioisotope Center (CYRIC), Tohoku University, Sendai 980-8578 (Japan); Ignatyuk, A.V. [Institute of Physics and Power Engineering (IPPE), Obninsk 249020 (Russian Federation)

    2010-01-15

    Cross sections for production of the therapeutic radioisotope {sup 131}Cs via the {sup 133}Cs(p,3n){sup 131}Ba{yields}{sup 131}Cs route were investigated at cyclotrons. Excitation functions of the {sup 133}Cs(p,x){sup 133m,133mg,131mg,129g,129m,128}Ba, {sup 132,129cum,127cum}Cs and {sup 129m(ind),127cum,125cum}Xe nuclear reactions were measured up to 70 MeV proton energy. The experimental data were compared to the results of model calculations performed by means of ALICE-IPPE, EMPIRE-II and TALYS computer codes. Good overall agreement was observed. On the basis of the measured excitation functions integral yields were deduced. Charged particle production routes of {sup 131}Cs are discussed.

  12. Adsorption of carbon dioxide (CO2) at S functionalized boron nitride (BN) and aluminum nitride (AlN) nanotubes (9, 0): A quantum chemical investigation

    Science.gov (United States)

    Najafi, Meysam

    2016-10-01

    We employed density functional theory to characterize CO2 adsorption on BNNT and AlNNT surfaces. The effects of S functionalization on the adsorption of CO2 gas on BNNT and AlNNT surfaces were investigated. Results reveal that adsorptions of CO2 on studied nanotubes were exothermic and experimentally possible from the energetic viewpoint. Results show that, Ead values of CO2 on AlNNT surface were more negative than corresponding values of BNNT. Results reveal that, S functionalization of studied nanotubes causes an increase in the absolute values of Ead of CO2 on surface of studied nanotubes. These results show that, there are good linearity dependencies between Ead and orbital energy values of studied nanotubes. Therefore we can conclude the Ead and orbital energy values are highly sensitive to the adsorption process which these may be used for the selection the suitable nanotubes with enhanced CO2 adsorption potential.

  13. Centrifugal casting processes of manufacturing in situ functionally gradient composite materials of Al-19Si-5Mg alloy

    Institute of Scientific and Technical Information of China (English)

    XIE Yong; LIU Changming; ZHAI Yanbo; WANG Kai; LING Xuedong

    2009-01-01

    Cylindrical components of in situ functionally gradient composite materials of Al-19Si-5Mg alloy were manufactured by centrifugal casting. Microstructure characteristics of the manufactured components were observed and the effects of the used process factors on these character-istics were analyzed. The results of observations shows that, in thickness, the components possess microstructures accumulating lots of Mg2Si particles and a portion of primary silicon particles in the inner layer, a little Mg2Si and primary silicon particles in the outer layer, and without any Mg2Si and primary silicon particle in the middle layer. The results of the analysis indicate that the rotation rate of centrifugal casting, mould temperature, and melt pouring temperature have evidently affected the accumulation of the second phase particles. Also, the higher the centrifugal rotation rate, mould temperature, and melt pouring temperature are, the more evident in the inner layer the degree of accumulation of Mg2Si and primary silicon particles is.

  14. Structural and functional properties of Al:ZnO thin films grown by Pulsed Laser Deposition at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Gondoni, P.; Ghidelli, M. [Dipartimento di Energia and NEMAS - Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Di Fonzo, F. [Center for Nano Science and Technology Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy); Russo, V. [Dipartimento di Energia and NEMAS - Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Bruno, P.; Marti-Rujas, J. [Center for Nano Science and Technology Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy); Bottani, C.E.; Li Bassi, A. [Dipartimento di Energia and NEMAS - Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Center for Nano Science and Technology Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy); Casari, C.S., E-mail: carlo.casari@polimi.it [Dipartimento di Energia and NEMAS - Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, via Ponzio 34/3, 20133 Milano (Italy); Center for Nano Science and Technology Polimi, Istituto Italiano di Tecnologia, via Pascoli 70/3, 20133 Milano (Italy)

    2012-05-01

    Current research on transparent conductive oxides (TCOs) is focusing on indium-free TCOs, such as Al-doped ZnO (AZO), as an alternative to indium-tin oxide. In this work, AZO thin films were grown by Pulsed Laser Deposition at room temperature in oxygen atmosphere. The O{sub 2} pressure was varied from 0.01 Pa to 10 Pa, highlighting the effects of defect formation and oxygen vacancies on the film properties. Structural properties were characterized by X-ray diffraction and Scanning Electron Microscopy, while functional properties were characterized by measurement of electrical conductivity, Hall mobility, carrier density and optical transmission. At an optimal deposition pressure of 2 Pa, optical transparency in the visible range and minimum resistivity (4.5 Bullet-Operator 10{sup -4} {Omega} cm) were found, comparable to state-of-the-art TCOs. Mean value of visible transparency was shown to increase with increasing pressure, up to 88% at a deposition pressure of 10 Pa.

  15. A Density Functional Theory Study of Codoping Characteristics of Sulfur with Alkaline Earth in Delafossite CuAlO2

    Science.gov (United States)

    Liu, Qi-Jun; Qin, Han; Liu, Zheng-Tang

    2016-04-01

    The structural, electronic properties and formation energies of sulfur and alkaline earth codoped delafossite CuAlO2 have been investigated using the first-principles density functional theory calculations. Our results reveal that the volume of codoping systems increases with the increasing atomic radius of metal atoms. The formation energies under different growth conditions have been calculated, showing that the codoping systems are formed easily under O-rich growth conditions. Electronic band structures and density of states have been obtained. The decreased bandgaps, enhanced covalence and appearance of electron acceptors after codoping are all good for p-type conductivity. Supported by the National Natural Science Foundation of China under Grant Nos. 11347199, 51402244, and 11547311, the Specialized Research Fund for Doctoral Program of Higher Education of China under Grant No. 20130184120028, the Fundamental Research Fund for the Central Universities, China under Grant Nos. 2682014CX084, 2682014ZT30, and 2682014ZT31, and the fund of the State Key Laboratory of Solidification Processing in NWPU under Grant No. SKLSP201511

  16. Differential modulation of changes in hippocampal-septal synaptic excitability by the amygdala as a function of either elemental or contextual fear conditioning in mice.

    Science.gov (United States)

    Desmedt, A; Garcia, R; Jaffard, R

    1998-01-01

    Recent data obtained using a classic fear conditioning paradigm showed a dissociation between the retention of associations relative to contextual information (dependent on the hippocampal formation) and the retention of elemental associations (dependent on the amygdala). Furthermore, it was reported that conditioned emotional responses (CERs) could be dissociated from the recollection of the learning experience (declarative memory) in humans and from modifications of the hippocampal-septal excitability in animals. Our aim was to determine whether these two systems ("behavioral expression" system and "factual memory" system) interact by examining the consequences of amygdalar lesions (1) on the modifications of hippocampal-septal excitability and (2) on the behavioral expression of fear (freezing) resulting from an aversive conditioning during reexposure to conditional stimuli (CSs). During conditioning, to modulate the predictive nature of the context and of a discrete stimulus (tone) on the unconditional stimulus (US) occurrence, the phasic discrete CS was paired with the US or randomly distributed with regard to the US. After the lesion, the CER was dramatically reduced during reexposure to the CSs, whatever the type of acquisition. However, the changes in hippocampal-septal excitability persisted but were altered. For controls, a decrease in septal excitability was observed during reexposure to the conditioning context only for the "unpaired group" (predictive context case). Conversely, among lesioned subjects this decrease was observed in the "paired group" (predictive discrete CS case), whereas this decrease was significantly reduced in the unpaired group with respect to the matched control group. The amplitude and the direction of these modifications suggest a differential modulation of hippocampal-septal excitability by the amygdala to amplify the contribution of the more predictive association signaling the occurrence of the aversive event.

  17. Time-dependent coupling of electron energy distribution function, vibrational kinetics of the asymmetric mode of CO2 and dissociation, ionization and electronic excitation kinetics under discharge and post-discharge conditions

    Science.gov (United States)

    Pietanza, L. D.; Colonna, G.; D'Ammando, G.; Capitelli, M.

    2017-01-01

    A time-dependent self-consistent model based on the coupling of the Boltzmann equation for the electron energy distribution function (EEDF) with the non-equilibrium vibrational kinetics of the asymmetric mode, as well as a simplified global model, have been implemented for a pure CO2 plasma. The simplified time-dependent global model takes into account dissociation and ionization as well as the reverse of these processes. It also takes into account the excitation/de-excitation of an electronic excited state at 10.5 eV. The model has been applied to describe the discharge and post-discharge conditions typically met in an atmospheric-pressure dielectric barrier discharge (DBD) and in a moderate-pressure microwave discharge. The reported results show the strong coupling between the excited state and the electron energy distribution kinetics due to superelastic (vibrational and electronic) collisions. Moreover, the dissociation rate from a pure vibrational mechanism can become competitive with the corresponding rate from the direct electron impact mechanism at high values of vibrational temperature.

  18. Molecular properties of excited electronic state: formalism, implementation, and applications of analytical second energy derivatives within the framework of the time-dependent density functional theory/molecular mechanics.

    Science.gov (United States)

    Zeng, Qiao; Liu, Jie; Liang, WanZhen

    2014-05-14

    This work extends our previous works [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011); J. Liu and W. Z. Liang, J. Chem. Phys. 135, 184111 (2011)] on analytical excited-state energy Hessian within the framework of time-dependent density functional theory (TDDFT) to couple with molecular mechanics (MM). The formalism, implementation, and applications of analytical first and second energy derivatives of TDDFT/MM excited state with respect to the nuclear and electric perturbations are presented. Their performances are demonstrated by the calculations of adiabatic excitation energies, and excited-state geometries, harmonic vibrational frequencies, and infrared intensities for a number of benchmark systems. The consistent results with the full quantum mechanical method and other hybrid theoretical methods indicate the reliability of the current numerical implementation of developed algorithms. The computational accuracy and efficiency of the current analytical approach are also checked and the computational efficient strategies are suggested to speed up the calculations of complex systems with many MM degrees of freedom. Finally, we apply the current analytical approach in TDDFT/MM to a realistic system, a red fluorescent protein chromophore together with part of its nearby protein matrix. The calculated results indicate that the rearrangement of the hydrogen bond interactions between the chromophore and the protein matrix is responsible for the large Stokes shift.

  19. Assessment of charge-transfer excitations with time-dependent, range-separated density functional theory based on long-range MP2 and multiconfigurational self- consistent field wave functions

    DEFF Research Database (Denmark)

    Hedegård, Erik D.; Jensen, Hans Jørgen Aagaard; Knecht, Stefan;

    2013-01-01

    formulation of multi-determinantal TD-DFT schemes where excitation classes, which are absent in conventional TD-DFT spectra (like for example double excitations), can be addressed. This paper investigates the combination of both the long-range Multi-Configuration Self-Consistent Field (MCSCF) and Second Order...... TD-MC-srDFT and performs slightly better against the reference data for this small subset. Beyond the proof-of-principle calculations comprising the first part of this contribution, we additionally studied the low-lying singlet excited states (S1 and S2) of the retinal chromophore. The chromophore...... displays multireference character in the ground state and both excited states exhibit considerable double excitation character, which in turn cannot be described within standard TD-DFT, due to the adiabatic approximation. However, a TD-MC-srDFT approach can account for the multireference character...

  20. The first quadrupole excitations in spherical nuclei and nuclear pairing

    Directory of Open Access Journals (Sweden)

    Saperstein E. E.

    2012-12-01

    Full Text Available Excitation energies and transition probabilities of the first 2+ excitations in even lead, tin and nickel isotopes are calculated within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. A reasonable agreement with available experimental data is obtained. The effect of the density dependence of the effective pairing interaction is analyzed in detail by comparing results obtained with volume and surface pairing. The effect is found to be noticeable, especially for the 2+-energies which are systematically higher at 200–300 keV for the volume paring as compared with the surface pairing case, the latterbeing in a better agreement with the data.

  1. Evaluation of thermal resistance constitution for packaged AlGaN/GaN high electron mobility transistors by structure function method

    Institute of Scientific and Technical Information of China (English)

    Zhang Guang-Chen; Feng Shi-Wei; Zhou Zhou; Li Jing-Wan; Guo Chun-Sheng

    2011-01-01

    The evaluation of thermal resistance constitution for packaged AlGaN/GaN high electron mobility transistor (HEMT) by structure function method is proposed in this paper. The evaluation is based on the transient heating measurement of the AlGaN/GaN HEMT by pulsed electrical temperature sensitive parameter method. The extracted chip-level and package-level thermal resistances of the packaged multi-finger AlGaN/GaN HEMT with 400-μn SiC substrate are 22.5 K/W and 7.2 K/W respectively, which provides a non-invasive method to evaluate the chip-level thermal resistance of packaged AlGaN/GaN HEMTs. It is also experimentally proved that the extraction of the chip-level thermal resistance by this proposed method is not influenced by package form of the tested device and temperature boundary condition of measurement stage.

  2. The stability and electronic structures of Si/O/Al/P atom doped (5,0)boron nitrogen nanotubes with Stone-Wales defects: Density functional theory studies

    Science.gov (United States)

    Li, KeJing; Ye, JinQian; Zhang, Juan; Wang, XiYuan; Shao, QingYi

    2017-03-01

    Using density functional theory, we have investigated Si/O/Al/P atoms doped (5,0)BNNTs with SW defects. We have mainly found that Si/O/Al/P have improved the stability of (5,0)BNNTs with SW defects. In view of Mulliken charge, we have thought Si/O/Al/P atoms have donated electrons (charge +e state or charge -e state) to nanotubes, contributing BNNTs with SW defects to stable. Meanwhile, from the aspect of energy band structure and DOS, we have further explained the reason. We have considerred that stability of doped structures has related to hybridization between doped atom and BNNTs. The stability has changed with changing the degree of hybridization. Moreover, B atom can play a crucial role in the insertion of Si/O/Al/P atom into (5,0)BNNTs with SW defects.

  3. Effects of aerobic exercise therapy and cognitive behavioural therapy on functioning and quality of life in amyotrophic lateral sclerosis: protocol of the FACTS-2-ALS trial

    Directory of Open Access Journals (Sweden)

    van de Weerd Margreet GH

    2011-06-01

    Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal progressive neurodegenerative disorder affecting motor neurons in the spinal cord, brainstem and motor cortex, leading to muscle weakness. Muscle weakness may result in the avoidance of physical activity, which exacerbates disuse weakness and cardiovascular deconditioning. The impact of the grave prognosis may result in depressive symptoms and hopelessness. Since there is no cure for ALS, optimal treatment is based on symptom management and preservation of quality of life (QoL, provided in a multidisciplinary setting. Two distinctly different therapeutic interventions may be effective to improve or preserve daily functioning and QoL at the highest achievable level: aerobic exercise therapy (AET to maintain or enhance functional capacity and cognitive behavioural therapy (CBT to improve coping style and cognitions in patients with ALS. However, evidence to support either approach is still insufficient, and the underlying mechanisms of the approaches remain poorly understood. The primary aim of the FACTS-2-ALS trial is to study the effects of AET and CBT, in addition to usual care, compared to usual care alone, on functioning and QoL in patients with ALS. Methods / Design A multicentre, single-blinded, randomized controlled trial with a postponed information model will be conducted. A sample of 120 patients with ALS (1 month post diagnosis will be recruited from 3 university hospitals and 1 rehabilitation centre. Patients will be randomized to one of three groups i.e. (1 AET + usual care, (2 CBT + usual care, (3 Usual care. AET consists of a 16-week aerobic exercise programme, on 3 days a week. CBT consists of individual psychological support of patients in 5 to 10 sessions over a 16-week period. QoL, functioning and secondary outcome measures will be assessed at baseline, immediately post intervention and at 3- and 6-months follow-up. Discussion The FACTS-2-ALS study is the first

  4. Excited-State Geometry Optimization with the Density Matrix Renormalization Group, as Applied to Polyenes.

    Science.gov (United States)

    Hu, Weifeng; Chan, Garnet Kin-Lic

    2015-07-14

    We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al. [J. Chem. Theor. Comput. 2013, 9, 4462]. We introduce a DMRG wave function maximum overlap following technique to facilitate state-specific DMRG excited-state optimization. Using DMRG configuration interaction (DMRG-CI) gradients, we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited-state geometries, as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.

  5. Field-induced doping-mediated tunability in work function of Al-doped ZnO: Kelvin probe force microscopy and first-principle theory.

    Science.gov (United States)

    Kumar, Mohit; Mookerjee, Sumit; Som, Tapobrata

    2016-09-16

    We demonstrate that the work function of Al-doped ZnO (AZO) can be tuned externally by applying an electric field. Our experimental investigations using Kelvin probe force microscopy show that by applying a positive or negative tip bias, the work function of AZO film can be enhanced or reduced, which corroborates well with the observed charge transport using conductive atomic force microscopy. These findings are further confirmed by calculations based on first-principles theory. Tuning the work function of AZO by applying an external electric field is not only important to control the charge transport across it, but also to design an Ohmic contact for advanced functional devices.

  6. Field-induced doping-mediated tunability in work function of Al-doped ZnO: Kelvin probe force microscopy and first-principle theory

    Science.gov (United States)

    Kumar, Mohit; Mookerjee, Sumit; Som, Tapobrata

    2016-09-01

    We demonstrate that the work function of Al-doped ZnO (AZO) can be tuned externally by applying an electric field. Our experimental investigations using Kelvin probe force microscopy show that by applying a positive or negative tip bias, the work function of AZO film can be enhanced or reduced, which corroborates well with the observed charge transport using conductive atomic force microscopy. These findings are further confirmed by calculations based on first-principles theory. Tuning the work function of AZO by applying an external electric field is not only important to control the charge transport across it, but also to design an Ohmic contact for advanced functional devices.

  7. Effect of low-level laser therapy (GaAlAs - λ660 nm on muscle function

    Directory of Open Access Journals (Sweden)

    Vania Maria de Araújo Giaretta

    Full Text Available Introduction:Low-level laser therapy (LLLT is effective in preventing fatigue and in stimulating the microcirculation and cellular activity. In this study, we examined the effect of LLLT on injured tibial muscle in vivo by assessing muscle function during fatigue.MethodsTwenty-four male mice were used. Each mouse received an injection of sterile 0.9% saline solution (50 µL in the right tibialis anterior muscle, after which the tendon of the muscle was exposed, connected to an isometric transducer and subjected to a resting tension of 1 g. A bipolar electrode was attached to the tibial nerve for electrical stimulation. The mice were randomly allocated to one of two groups: G1 (control: 3 h – n=8 and 9 h – n=5 and G2 (treated with GaAlAs laser, λ660 nm, 35 mW, 0.6 J, 17 s: 3 h – n=6 and 9 h – n=5.ResultsIn G1 mice, the amplitude of the tetanic contracture in response to induced fatigue remained unchanged during six consecutive tetani. The amplitude of the tetanic contractions in response to electrical stimulation (4-8 mV was also unchanged. These results indicated muscle intactness in response to the load imposed by tetanus. In G2 mice, there was an increase in the amplitude of contraction after 3 h and 9 h when compared to G1 at 83% tetanus.ConclusionThese results indicate that exposure of muscle to LLLT enhanced the contractile force and increased the resistance to muscle fatigue without causing morphological damage to cellular structures.

  8. Effect of bi-layer ratio in ZnO/Al2O3 multilayers on microstructure and functional properties of ZnO nanocrystals embedded in Al2O3 matrix

    Science.gov (United States)

    Sekhar, K. C.; Levichev, S.; Buljan, M.; Bernstorff, S.; Kamakshi, Koppole; Chahboun, A.; Almeida, A.; Agostinho Moreira, J.; Pereira, M.; Gomes, M. J. M.

    2014-04-01

    Zinc oxide (ZnO) nanocrystals (NCs) embedded in alumina (Al2O3) matrix were produced via rapid thermal annealing (RTA) of pulsed laser deposited ZnO/Al2O3 multilayered nanostructures. The effect of the thickness ratio ( R) between Al2O3 and ZnO in one bi-layer on the microstructure and functional properties of NCs has been investigated. Grazing incidence small angle X-ray scattering confirmed the formation of nanocrystals after RTA. Grazing incidence wide angle X-ray scattering studies revealed that ZnO NCs have a high crystalline quality with (100) as preferred orientation. Tensile strain of NCs decreases with increasing R and is correlated to the distribution of NCs. From Raman analysis, it is noticed that the phonon frequency of the E2 mode, related to the ZnO wurtzite phase, in NCs is shifted towards that of bulk ZnO with increasing R. Photoluminescence studies revealed that the near edge peak position shifts from 382 nm to 371 nm as the ratio R changes from 1.5 to 4 and is attributed to the strain effect. The intensity of emission in the yellow-green region due to defects decreases significantly with increasing R. Current-voltage ( I- V) characteristics of Al/ZnO NCs embedded in Al2O3/n-Si (100)/Al have shown a hysteresis behavior. The increasing width of the hysteresis with increasing R revealed that the origin of the hysteresis might be due to the existence of polar surface charges on well-separated NCs. The high-resistance and low-resistance states in I- V hysteresis curves seem to be governed by Fowler-Nordheim tunneling and Schottky emission mechanisms, respectively.

  9. Adsorption of carbon dioxide (CO{sub 2}) at S functionalized boron nitride (BN) and aluminum nitride (AlN) nanotubes (9, 0): A quantum chemical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, Meysam, E-mail: meysamnajafi2016@yahoo.com

    2016-10-30

    Highlights: • AlN-NT has higher potential to CO{sub 2} adsorption in comparison to BN-NT. • S functionalization of studied nanotubes improve the CO{sub 2} adsorption ability of them. • E{sub ad} is suitable scale to propose the novel toxic gas sensor based on nanostructured. • E{sub ad} and E{sub HLG} of studied nanotubes have linear dependences. - Abstract: We employed density functional theory to characterize CO{sub 2} adsorption on BNNT and AlNNT surfaces. The effects of S functionalization on the adsorption of CO{sub 2} gas on BNNT and AlNNT surfaces were investigated. Results reveal that adsorptions of CO{sub 2} on studied nanotubes were exothermic and experimentally possible from the energetic viewpoint. Results show that, E{sub ad} values of CO{sub 2} on AlNNT surface were more negative than corresponding values of BNNT. Results reveal that, S functionalization of studied nanotubes causes an increase in the absolute values of E{sub ad} of CO{sub 2} on surface of studied nanotubes. These results show that, there are good linearity dependencies between E{sub ad} and orbital energy values of studied nanotubes. Therefore we can conclude the E{sub ad} and orbital energy values are highly sensitive to the adsorption process which these may be used for the selection the suitable nanotubes with enhanced CO{sub 2} adsorption potential.

  10. On the risks of using dendrograms to measure functional diversity and multidimensional spaces to measure phylogenetic diversity: a comment on Sobral et al. (2016).

    Science.gov (United States)

    Villéger, Sébastien; Maire, Eva; Leprieur, Fabien

    2017-04-01

    Sobral et al. (Ecology Letters, 19, 2016, 1091) reported that the loss of bird functional and phylogenetic diversity due to species extinctions was not compensated by exotic species introductions. Here, we demonstrate that the reported changes in biodiversity were underestimated because of methodological pitfalls.

  11. Total photoionization cross-sections of excited electronic states by the algebraic diagrammatic construction-Stieltjes-Lanczos method

    Science.gov (United States)

    Ruberti, M.; Yun, R.; Gokhberg, K.; Kopelke, S.; Cederbaum, L. S.; Tarantelli, F.; Averbukh, V.

    2014-05-01

    Here, we extend the L2 ab initio method for molecular photoionization cross-sections introduced in Gokhberg et al. [J. Chem. Phys. 130, 064104 (2009)] and benchmarked in Ruberti et al. [J. Chem. Phys. 139, 144107 (2013)] to the calculation of total photoionization cross-sections of molecules in electronically excited states. The method is based on the ab initio description of molecular electronic states within the many-electron Green's function approach, known as algebraic diagrammatic construction (ADC), and on the application of Stieltjes-Chebyshev moment theory to Lanczos pseudospectra of the ADC electronic Hamiltonian. The intermediate state representation of the dipole operator in the ADC basis is used to compute the transition moments between the excited states of the molecule. We compare the results obtained using different levels of the many-body theory, i.e., ADC(1), ADC(2), and ADC(2)x for the first two excited states of CO, N2, and H2O both at the ground state and the excited state equilibrium or saddle point geometries. We find that the single excitation ADC(1) method is not adequate even at the qualitative level and that the inclusion of double electronic excitations for description of excited state photoionization is essential. Moreover, we show that the use of the extended ADC(2)x method leads to a substantial systematic difference from the strictly second-order ADC(2). Our calculations demonstrate that a theoretical modelling of photoionization of excited states requires an intrinsically double excitation theory with respect to the ground state and cannot be achieved by the standard single excitation methods with the ground state as a reference.

  12. Sadomasochism, sexual excitement, and perversion.

    Science.gov (United States)

    Kernberg, O F

    1991-01-01

    Sadomasochism, an ingredient of infantile sexuality, is an essential part of normal sexual functioning and love relations, and of the very nature of sexual excitement. Sadomasochistic elements are also present in all sexual perversions. Sadomasochism starts out as the potential for erotic masochism in both sexes, and represents a very early capacity to link aggression with the libidinal elements of sexual excitement. Sexual excitement may be considered a basic affect that overcomes primitive splitting of love and hatred. Erotic desire is a more mature form of sexual excitement. Psychoanalytic exploration makes it possible to uncover the unconscious components of sexual excitement: wishes for symbiotic fusion and for aggressive penetration and intermingling; bisexual identifications; the desire to transgress oedipal prohibitions and the secretiveness of the primal scene, and to violate the boundaries of a teasing and withholding object. The relation between these wishes and the development of erotic idealization processes in both sexes is explored in the context of a critical review of the pertinent psychoanalytic literature.

  13. Multi-frequency excitation

    KAUST Repository

    Younis, Mohammad I.

    2016-03-10

    Embodiments of multi-frequency excitation are described. In various embodiments, a natural frequency of a device may be determined. In turn, a first voltage amplitude and first fixed frequency of a first source of excitation can be selected for the device based on the natural frequency. Additionally, a second voltage amplitude of a second source of excitation can be selected for the device, and the first and second sources of excitation can be applied to the device. After applying the first and second sources of excitation, a frequency of the second source of excitation can be swept. Using the methods of multi- frequency excitation described herein, new operating frequencies, operating frequency ranges, resonance frequencies, resonance frequency ranges, and/or resonance responses can be achieved for devices and systems.

  14. Adsorption properties of CO, H2 and CH4 over Pd/γ-Al2O3 catalyst: A density functional study

    Science.gov (United States)

    Song, Zijian; Wang, Ben; Yu, Jie; Ma, Chuan; Qu, Qinggong; Zeng, Zhao; Xiang, Jun; Hu, Song; Sun, Lushi

    2016-11-01

    Density functional theory (DFT) calculations were employed to investigate the adsorption characteristics of carbon monoxide (CO), hydrogen (H2), and methane (CH4) on the surface of clean γ-Al2O3 and Pd supported γ-Al2O3, which is of significant for catalytic combustion. The adsorption intensities of the three gas molecules in pure γ-Al2O3 (1 1 0) and Pd/γ-Al2O3 (1 1 0) were in the order of CO > H2 > CH4. The corresponding adsorption energies on the Pd/γ-Al2O3 (1 1 0) surface were at least three times higher than those on γ-Al2O3 (1 1 0). Anlysis of Mulliken population and partial density of states (PDOS) showed that the adsorption mechanisms were as follow: (a) CO stably adsorbed on the bridge site of dimer Pd with two Csbnd Pd bonds because of charges transfer from the surface to CO, and the triple bond (Ctbnd O) was broken to a double bond (Cdbnd O); (b) H2 was dissociated into hydrogen atoms on the dimer Pd and produced a stable planar configuration; and (c) the tetrahedral structure of CH4 was destroyed on the surface and formed a sbnd CH3 species bonded to the Pd atom, which contributes to the orbital hybridization between C and Pd atoms.

  15. Valence excitation energies of alkenes, carbonyl compounds, and azabenzenes by time-dependent density functional theory: Linear response of the ground state compared to collinear and noncollinear spin-flip TDDFT with the Tamm-Dancoff approximation

    Science.gov (United States)

    Isegawa, Miho; Truhlar, Donald G.

    2013-04-01

    Time-dependent density functional theory (TDDFT) holds great promise for studying photochemistry because of its affordable cost for large systems and for repeated calculations as required for direct dynamics. The chief obstacle is uncertain accuracy. There have been many validation studies, but there are also many formulations, and there have been few studies where several formulations were applied systematically to the same problems. Another issue, when TDDFT is applied with only a single exchange-correlation functional, is that errors in the functional may mask successes or failures of the formulation. Here, to try to sort out some of the issues, we apply eight formulations of adiabatic TDDFT to the first valence excitations of ten molecules with 18 density functionals of diverse types. The formulations examined are linear response from the ground state (LR-TDDFT), linear response from the ground state with the Tamm-Dancoff approximation (TDDFT-TDA), the original collinear spin-flip approximation with the Tamm-Dancoff (TD) approximation (SF1-TDDFT-TDA), the original noncollinear spin-flip approximation with the TDA approximation (SF1-NC-TDDFT-TDA), combined self-consistent-field (SCF) and collinear spin-flip calculations in the original spin-projected form (SF2-TDDFT-TDA) or non-spin-projected (NSF2-TDDFT-TDA), and combined SCF and noncollinear spin-flip calculations (SF2-NC-TDDFT-TDA and NSF2-NC-TDDFT-TDA). Comparing LR-TDDFT to TDDFT-TDA, we observed that the excitation energy is raised by the TDA; this brings the excitation energies underestimated by full linear response closer to experiment, but sometimes it makes the results worse. For ethylene and butadiene, the excitation energies are underestimated by LR-TDDFT, and the error becomes smaller making the TDA. Neither SF1-TDDFT-TDA nor SF2-TDDFT-TDA provides a lower mean unsigned error than LR-TDDFT or TDDFT-TDA. The comparison between collinear and noncollinear kernels shows that the noncollinear kernel

  16. GAMA/WiggleZ: The 1.4GHz radio luminosity functions of high- and low-excitation radio galaxies and their redshift evolution to z=0.75

    CERN Document Server

    Pracy, Michael; Sadler, Elaine; Croom, Scott; Baldry, Ivan; Bland-Hawthorn, Joss; Brough, Sarah; Brown, Michael; Couch, Warrick; Davis, Tamara; Drinkwater, Michael; Hopkins, Andrew; Jarvis, Matt; Jelliffe, Ben; Jurek, Russell; Loveday, Jon; Pimbblet, Kevin; Prescott, Matt; Wisniosk, Emily; Woods, David

    2016-01-01

    We present radio Active Galactic Nuclei (AGN) luminosity functions over the redshift range 0.005 < z < 0.75. The sample from which the luminosity functions are constructed is an optical spectroscopic survey of radio galaxies, identified from matched Faint Images of the Radio Sky at Twenty-cm survey (FIRST) sources and Sloan Digital Sky Survey (SDSS) images.The radio AGN are separated into Low Excitation Radio Galaxies (LERGs) and High Excitation Radio Galaxies (HERGs) using the optical spectra. We derive radio luminosity functions for LERGs and HERGs separately in the three redshift bins (0.005 < z < 0.3, 0.3 < z < 0.5 and 0.5 < z <0.75). The radio luminosity functions can be well described by a double power-law. Assuming this double power-law shape the LERG population displays little or no evolution over this redshift range evolving as ~$(1+z)^{0.06}$ assuming pure density evolution or ~ $(1+z)^{0.46}$ assuming pure luminosity evolution. In contrast, the HERG population evolves more r...

  17. Atomic to Nanoscale Investigation of Functionalities of an Al2O3 Coating Layer on a Cathode for Enhanced Battery Performance

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Pengfei; Zheng, Jianming; Zhang, Xiaofeng; Xu, Rui; Amine, Khalil; Xiao, J; Zhang, Ji-Guang; Wang, Chong-Min

    2016-02-09

    Surface coating has been identified as an effective approach for enhancing the capacity retention of layered structure cathode. However, the underlying operating mechanism of such a thin coating layer, in terms of surface chemical functionality and capacity retention, remains unclear. In this work, we use aberration-corrected scanning transmission electron microscopy and high-efficiency spectroscopy to probe the delicate functioning mechanism of an Al2O3 coating layer on a Li1.2Ni0.2Mn0.6O2 cathode. We discovered that in terms of surface chemical function, the Al2O3 coating suppresses the side reaction between the cathode and the electrolyte during battery cycling. At the same time, the Al2O3 coating layer also eliminates the chemical reduction of Mn from the cathode particle surface, therefore preventing the dissolution of the reduced Mn into the electrolyte. In terms of structural stability, we found that the Al2O3 coating layer can mitigate the layer to spinel phase transformation, which otherwise will be initiated from the particle surface and propagate toward the interior of the particle with the progression of battery cycling. The atomic to nanoscale effects of the coating layer observed here provide insight into the optimized design of a coating layer on a cathode to enhance the battery properties.

  18. Metal-insulator transition at the LaAlO3/SrTiO3 interface revisited: A hybrid functional study

    KAUST Repository

    Cossu, Fabrizio

    2013-07-17

    We investigate the electronic properties of the LaAlO3/SrTiO3 interface using density functional theory. In contrast to previous studies, which relied on (semi-)local functionals and the GGA+U method, we here use a recently developed hybrid functional to determine the electronic structure. This approach offers the distinct advantage of accessing both the metallic and insulating multilayers on a parameter-free equal footing. As compared to calculations based on semilocal GGA functionals, our hybrid functional calculations lead to a considerably increased band gap for the insulating systems. The details of the electronic structure show substantial deviations from those obtained by GGA calculations. This casts severe doubts on all previous results based on semilocal functionals. In particular, corrections using rigid band shifts (“scissors operator”) cannot lead to valid results.

  19. Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Junjie [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Li, Jiadong; Miao, Bin; Wu, Dongmin, E-mail: dmwu2008@sinano.ac.cn [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wang, Jine; Pei, Renjun, E-mail: rjpei2011@sinano.ac.cn [Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-08-25

    An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup −14} to 10{sup −8} M and a detection limit below 10{sup −14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

  20. CN rotational excitation

    Science.gov (United States)

    Palazzi, E.; Mandolesi, N.; Crane, Philippe

    1992-10-01

    We report the results of a search for new lines of sight in which to study the CN excitation and a statistical analysis of all the excitation temperatures measured using interstellar CN. This data set strongly confirms that the cosmic background radiation (CBR) is the dominant contributor to the excitation of CN, and demonstrates the homogeneity of the CBR. Thirty-five observations is a sufficiently large sample to look for the presence of systematic effects in the CN excitation. The weighted average of the CN excitation temperatures exceeds the T(CBR) obtained by COBE and the Canadian rocket by 82 +/- 30 mK. With the aim of looking at the origin of this difference, we have considered in detail the known mechanisms that could contribute to exciting the CN molecule. None of the data necessary to quantify these mechanisms are of sufficient quality to provide a clean explanation of the observed difference.

  1. Microstructural Evolution and Functional Properties of Fe-Mn-Al-Ni Shape Memory Alloy Processed by Selective Laser Melting

    Science.gov (United States)

    Niendorf, Thomas; Brenne, Florian; Krooß, Philipp; Vollmer, Malte; Günther, Johannes; Schwarze, Dieter; Biermann, Horst

    2016-06-01

    In the current study, a Fe-Mn-Al-Ni shape memory alloy is processed by additive manufacturing for the first time. Microstructural evolution upon processing is strongly affected by thermal gradients and solidification velocity and, thus, by processing parameters and the actual specimen geometry. By single-step solutionizing heat treatment pronounced grain growth is initiated leading to microstructures showing good reversibility. The compressive stress-strain response revealed maximum reversible pseudo-elastic strain of about 7.5 pct. Critical steps toward further optimization of additively manufactured Fe-Mn-Al-Ni shape memory alloys are discussed.

  2. Does anodal transcranial direct current stimulation enhance excitability of the motor cortex and motor function in healthy individuals and subjects with stroke: a systematic review and meta-analysis.

    Science.gov (United States)

    Bastani, A; Jaberzadeh, S

    2012-04-01

    The primary aim of this review is to evaluate the effects of anodal transcranial direct current stimulation (a-tDCS) on corticomotor excitability and motor function in healthy individuals and subjects with stroke. The secondary aim is to find a-tDCS optimal parameters for its maximal effects. Electronic databases were searched for studies into the effect of a-tDCS when compared to no stimulation. Studies which met the inclusion criteria were assessed and methodological quality was examined using PEDro and Downs and Black (D&B) assessment tools. Data from seven studies revealed increase in corticomotor excitability with a small but significant effect size (0.31 [0.14, 0.48], p=0.0003) in healthy subjects and data from two studies in subjects with stroke indicated significant results with moderate effect size (0.59 [0.24, 0.93], p=0.001) in favor of a-tDCS. Likewise, studies examining motor function demonstrated a small and non-significant effect (0.39 [-0.17, 0.94], p=0.17) in subjects with stroke and a large but non-significant effect (0.92 [-1.02, 2.87], p=0.35) in healthy subjects in favor of improvement in motor function. The results also indicate that efficacy of a-tDCS is dependent on current density and duration of application. A-tDCS increases corticomotor excitability in both healthy individuals and subjects with stroke. The results also show a trend in favor of motor function improvement following a-tDCS. A-tDCS is a non-invasive, cheap and easy-to-apply modality which could be used as a stand-alone technique or as an adds-on technique to enhance corticomotor excitability and the efficacy of motor training approaches. However, the small sample size of the included studies reduces the strength of the presented evidences and any conclusion in this regard should be considered cautiously.

  3. Measurement of the excitation function of {sup 65}Cu({sup 3}He,2n){sup 66}Ga; Medida da funcao excitacao da reacao {sup 65} Cu({sup 3} He,2n) {sup 66} Ga

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, M.A.V.; Vinagre Filho, U.M.; Costa, V.L. da [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    1996-07-01

    The excitation function of the {sup 65} Cu({sup 3} He,2n) {sup 66} Ga reaction was measured. It was performed by irradiation of several stacks of two copper foils with {sup 3} He until 36 MeV from the cyclotron CV-28 of IEN. The initial energy of {sup 3} He beam was measured by spectrometry of charged particles with Si (au) detector, placed at 90 deg C respecting to the incident beam. The activities was measured by gamma rays spectrometry using HPGe detector. The results are compared with others found in the literature. (author)

  4. Diagnostics of defects in AlGaN/GaN high electron mobility transitor (HEMT) epi-layers via spectroscopic photo current-voltage (IV) measurements with variable-wavelength ultraviolet (UV) and visible light excitation

    Science.gov (United States)

    Khanal, Min P.; Ozden, Burcu; Mirkhani, Vahid; Yapabandara, Kosala; Shehzad Sultan, Muhammad; Park, Minseo; Shen, Li

    The reliability and performance of the nitride high electron mobility transistors (HEMTs) have been plagued by deleterious phenomena such as current collapse which is believed to be produced by electrically-active deep-level defects (or traps) that reside at the surface/interfaces and in the bulk of the AlGaN/GaN HEMT layers. Therefore, identification of their physical/spectral locations and understanding the nature of defects is very important to improve the reliability of AlGaN/GaN HEMTs. In this work, deep-level defects and traps located in the AlGaN/GaN HEMT epi-layers were investigated by using spectroscopic photo IV measurements. An array of Schottky contacts was constructed on the HEMT layer produced by metal-organic chemical vapor deposition (MOCVD). The photo IV measurement was performed by collecting the photo current generated by the variable-wavelength UV/visible light illumination. It was successfully demonstrated that this technique can provide the information on the distribution of electrically-active defects along the in-depth direction and across the HEMT wafers. Therefore, it can be concluded that the spectroscopic measurements can be useful to assess the uniformity of defect distribution both along the in-depth direction and across the AlGaN/GaN wafers. Corresponding author.

  5. Recursive design of nonlinear H∞ excitation controller

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This work is concerned with the problem of L2 gain disturbance attenuation for nonlinear systems and nonlinear robust control for power systems. In terms of the recurrence design approach proposed, the nonnegative solution of dissipative inequality and the storage function of nonlinear H∞ control for a generator excitation system are acquired. From this storage function, the excitation controller is constructed. Moreover, simulation results manifest the effectiveness of this design method.

  6. Hard x-ray photoemission and density functional theory study of the internal electric field in SrTiO3/LaAlO3 oxide heterostructures

    Science.gov (United States)

    Slooten, E.; Zhong, Zhicheng; Molegraaf, H. J. A.; Eerkes, P. D.; de Jong, S.; Massee, F.; van Heumen, E.; Kruize, M. K.; Wenderich, S.; Kleibeuker, J. E.; Gorgoi, M.; Hilgenkamp, H.; Brinkman, A.; Huijben, M.; Rijnders, G.; Blank, D. H. A.; Koster, G.; Kelly, P. J.; Golden, M. S.

    2013-02-01

    A combined experimental and theoretical investigation of the electronic structure of the archetypal oxide heterointerface system LaAlO3 on SrTiO3 is presented. High-resolution, hard x-ray photoemission is used to uncover the occupation of Ti 3d states and the relative energetic alignment—and hence internal electric fields—within the LaAlO3 layer. First, the Ti 2p core-level spectra clearly show occupation of Ti 3d states already for two unit cells of LaAlO3. Second, the LaAlO3 core levels were seen to shift to lower binding energy as the LaAlO3 overlayer thickness, n, was increased, agreeing with the expectations from the canonical electron transfer model for the emergence of conductivity at the interface. However, not only is the energy offset of only ˜300 meV between n=2 (insulating interface) and n=6 (metallic interface) an order of magnitude smaller than the simple expectation, but it is also clearly not the sum of a series of unit-cell-by-unit-cell shifts within the LaAlO3 block. Both of these facts argue against the simple charge-transfer picture involving a cumulative shift of the LaAlO3 valence bands above the SrTiO3 conduction bands, resulting in charge transfer only for n≥4. We discuss effects which could frustrate this elegant and simple charge-transfer model, concluding that although it cannot be ruled out, photodoping by the x-ray beam is unlikely to be the cause of the observed behavior. Turning to the theoretical data, our density functional simulations show that the presence of oxygen vacancies at the LaAlO3 surface at the 25% level reverses the direction of the internal field in the LaAlO3. Therefore, taking the experimental and theoretical results together, a consistent picture emerges for real-life samples in which nature does not wait until n=4 and already for n=2 mechanisms other than internal-electric-field-driven electron transfer from idealized LaAlO3 to near-interfacial states in the SrTiO3 substrate are active in heading off the

  7. Fabrication and mechanical properties of Al2O3/SiC/ZrO2 functionally graded material by electrophoretic deposition.

    Science.gov (United States)

    Askari, E; Mehrali, M; Metselaar, I H S C; Kadri, N A; Rahman, Md M

    2012-08-01

    This study describes the synthesis of Al(2)O(3)/SiC/ZrO(2) functionally graded material (FGM) in bio-implants (artificial joints) by electrophoretic deposition (EPD). A suitable suspension that was based on 2-butanone was applied for the EPD of Al(2)O(3)/SiC/ZrO(2), and a pressureless sintering process was applied as a presintering. Hot isostatic pressing (HIP) was used to densify the deposit, with beneficial mechanical properties after 2 h at 1800 °C in Ar atmosphere. The maximum hardness in the outer layer (90 vol.% Al(2)O(3)+10 vol.% SiC) and maximum fracture toughness in the core layer (75 vol.% Al(2)O(3)+10 vol.% SiC + 15 vol.% ZrO(2)) composite were 20.8±0.3 GPa and 8±0.1 MPa m(1/2), respectively. The results, when compared with results from Al(2)O(3)/ZrO(2) FGM, showed that SiC increased the compressive stresses in the outer layers, while the inner layers were under a residual tensile stress.

  8. Novel Bio-functional Magnesium Coating on Porous Ti6Al4V Orthopaedic Implants: In vitro and In vivo Study

    Science.gov (United States)

    Li, Xiaokang; Gao, Peng; Wan, Peng; Pei, Yifeng; Shi, Lei; Fan, Bo; Shen, Chao; Xiao, Xin; Yang, Ke; Guo, Zheng

    2017-01-01

    Titanium and its alloys with various porous structures are one of the most important metals used in orthopaedic implants due to favourable properties as replacement for hard tissues. However, surface modification is critical to improve the osteointegration of titanium and its alloys. In this study, a bioactive magnesium coating was successfully fabricated on porous Ti6Al4V by means of arc ion plating, which was proved with fine grain size and high film/substrate adhesion. The surface composition and morphology were characterized by X-ray diffraction and SEM equipped with energy dispersive spectroscopy. Furthermore, the in vitro study of cytotoxicity and proliferation of MC3T3-E1 cells showed that magnesium coated porous Ti6Al4V had suitable degradation and biocompatibility. Moreover, the in vivo studies including fluorescent labelling, micro-computed tomography analysis scan and Van-Gieson staining of histological sections indicated that magnesium coated porous Ti6Al4V could significantly promote bone regeneration in rabbit femoral condylar defects after implantation for 4 and 8 weeks, and has better osteogenesis and osteointegration than the bare porous Ti6Al4V. Therefore, it is expected that this bioactive magnesium coating on porous Ti6Al4V scaffolds with improved osteointegration and osteogenesis functions can be used for orthopedic applications. PMID:28102294

  9. Excited states 2

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 2 is a collection of papers that deals with molecules in the excited states. The book describes the geometries of molecules in the excited electronic states. One paper describes the geometries of a diatomic molecule and of polyatomic molecules; it also discusses the determination of the many excited state geometries of molecules with two, three, or four atoms by techniques similar to diatomic spectroscopy. Another paper introduces an ordered theory related to excitons in pure and mixed molecular crystals. This paper also presents some experimental data such as those invo

  10. Excited states v.6

    CERN Document Server

    Lim, Edward C

    1982-01-01

    Excited States, Volume 6 is a collection of papers that discusses the excited states of molecules. The first paper discusses the linear polyene electronic structure and potential surfaces, considering both the theoretical and experimental approaches in such electronic states. This paper also reviews the theory of electronic structure and cites some experimental techniques on polyene excitations, polyene spectroscopic phenomenology, and those involving higher states of polyenes and their triplet states. Examples of these experimental studies of excited states involve the high-resolution one-pho

  11. Systemic injection of AAV9-GDNF provides modest functional improvements in the SOD1(G93A) ALS rat but has adverse side effects.

    Science.gov (United States)

    Thomsen, G M; Alkaslasi, M; Vit, J-P; Lawless, G; Godoy, M; Gowing, G; Shelest, O; Svendsen, C N

    2017-03-09

    Injecting proteins into the central nervous system that stimulate neuronal growth can lead to beneficial effects in animal models of disease. In particular, glial cell line-derived neurotrophic factor (GDNF) has shown promise in animal and cell models of Parkinson's disease, Huntington's disease and amyotrophic lateral sclerosis (ALS). Here, systemic AAV9-GDNF was delivered via tail vein injections to young rats to determine whether this could be a safe and functional strategy to treat the SOD1(G93A) rat model of ALS and, therefore, translated to a therapy for ALS patients. We found that GDNF administration in this manner resulted in modest functional improvement, whereby grip strength was maintained for longer and the onset of forelimb paralysis was delayed compared to non-treated rats. This did not, however, translate into an extension in survival. In addition, ALS rats receiving GDNF exhibited slower weight gain, reduced activity levels and decreased working memory. Collectively, these results confirm that caution should be applied when applying growth factors such as GDNF systemically to multiple tissues.Gene Therapy advance online publication, 9 March 2017; doi:10.1038/gt.2017.9.

  12. The chlorophyll a fluorescence induction pattern in chloroplasts upon repetitive single turnover excitations: accumulation and function of QB-nonreducing centers.

    Science.gov (United States)

    Vredenberg, Wim; Kasalicky, Vojtech; Durchan, Milan; Prasil, Ondrej

    2006-03-01

    The increase of chlorophyll fluorescence yield in chloroplasts in a 12.5 Hz train of saturating single turnover flashes and the kinetics of fluorescence yield decay after the last flash have been analyzed. The approximate twofold increase in Fm relative to Fo, reached after 30-40 flashes, is associated with a proportional change in the slow (1-20 s) component of the multiphasic decay. This component reflects the accumulation of a sizeable fraction of QB-nonreducing centers. It is hypothesized that the generation of these centers occurs in association with proton transport across the thylakoid membrane. The data are quantitatively consistent with a model in which the fluorescence quenching of QB-nonreducing centers is reversibly released after second excitation and electron trapping on the acceptor side of Photosystem II.

  13. Coherent acoustic excitation of cavity polaritons

    DEFF Research Database (Denmark)

    Poel, Mike van der; de Lima, M. M.; Hey, R.

    and highly nonlinear optical response.Our sample consists of epitaxially grown GaAs/AlGaAs QWs located at the anti-node ofa high Q lambda cavity, which is resonant with the QW excitonic transition3. The SAWfield, which is excited by an interdigital transducer on the piezoelectric GaAs samplesurface...

  14. Hydrogen dynamics in Na3AlH6: A combined density functional theory and quasielastic neutron scattering study

    DEFF Research Database (Denmark)

    Zsigmond, G.; Manoshin, S.; Lieutenant, K.

    2007-01-01

    Handling of polarization became very important in simulations of neutron scattering. One of the very comprehensive and open-source neutron simulation package, VITESS, has been intensely involved in polarized neutron simulations. Several examples will be shown here. Another similar package NISP al...

  15. Synchronization between excitation and response signals in frequency response function estimation for MIMO random vibration test%MIMO随机振动试验频响估计中激励和响应的同步方法

    Institute of Scientific and Technical Information of China (English)

    崔旭利; 陈怀海; 贺旭东; 姜双燕

    2012-01-01

    频响函数估计是多输入多输出随机振动试验控制算法中的必要环节.在振动环境试验中,通常不采集振动台的实际激励信号,而用实测的响应信号和计算机内存中的激励信号来进行系统频响函数估计.由于计算机内存中的激励信号与实际振动台上的激励信号之间在相位上存在着差异,从而导致实测的响应信号和计算机内存中的激励信号不同步.这给系统频响函数的估计带来了较大困难.为此,根据线性系统中激励和响应之间的关系,结合随机减量法,提出了一种二次相关法用于系统频响函数的估计,用该方法进行频响函数估计只需要采集响应信号.在三轴振动台上进行了对比试验,结果验证了所提出的二次相关法的正确性.%The estimation of frequency response functions ( FRFs) is unavoidable in MIMO ( multiple input and multiple output) random vibration test control. The actual excitation signals on the shaker tables are always not sampled during the vibration test. So, the FRFs are usually estimated by the response signals acturally measured and the excitation signals stored in the computer memory. Because there is a phase lag between the signal in the memory and the actual signal on the shaker table, the response signal is not synchronous with the memory excitation signal, which makes difficulty to estimat FRFs. Based on the relationship between the excitation and response in linear system and utilizing the random decrement technique, a dual correlation method ( DCM) was presented to estimate FRFs without measuring the actual driving force signals. A comparison test between DCM and the conventional method which needs to sample the excitation and response signals simultaneously was accomplished on a 3-axis vibration table. The result shows the correctness of the presented DCM.

  16. Effect of motor imagery on excitability of spinal neural function and its impact on the accuracy of movement-considering the point at which subjects subjectively determine the 50%MVC point.

    Science.gov (United States)

    Fukumoto, Yuki; Bunno, Yoshibumi; Suzuki, Toshiaki

    2016-12-01

    [Purpose] This study aimed to examine the effect of motor imagery on the accuracy of motion and the excitability of spinal neural function. [Subjects and Methods] Thirty healthy volunteers (males, 15; females, 15; mean age, 20.3 ± 1.0 years) were recruited. F-waves was recorded at rest, while holding a sensor, and while using motor imagery. Next, subjects learned 50% maximum voluntary contraction. The pinch force was measured without visual feedback before and after motor imagery. F-waves were analyzed with respect to persistence and the F/M amplitude ratio. Correction time and coefficient of variation were calculated from the pinch force. [Results] Persistence and F/M amplitude ratio ware significantly higher in the holding sensor and motor imagery conditions than in the resting condition. In addition, persistence under motor imagery was significantly higher than that in the holding sensor condition. No significant differences were observed in relative values of correction time and coefficient of variation between the two pinch action conditions. The pinch force in task 2 approximated a more authentic 50%MVC than that in task 1. [Conclusion] Motor imagery increases the excitability of spinal neural function, suggesting that it also affects accurate control of muscle force.

  17. Excitation functions of 125Te(p, xn)-reactions from their respective thresholds up to 100 MeV with special reference to the production of 124I.

    Science.gov (United States)

    Hohn, A; Nortier, F M; Scholten, B; van der Walt, T N; Coenen, H H; Qaim, S M

    2001-08-01

    Excitation functions of the nuclear reactions 125Te(p, xn) (119,120m, 120g, 121,122,123,124,125)I were measured for the first time from their respective thresholds up to 100 MeV using the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 98.3% enriched 125Te on Ti-backing. In addition to experimental studies, excitation functions were calculated by the modified hybrid model code ALICE-IPPE. The experimental and theoretical data generally showed good agreement. From the measured cross section data, integral yields of (123,124,125)I were calculated. The energy range Ep 21 --> 15 MeV appears to be very suitable for the production of the medically interesting radionuclide 124I (T(1/2) = 4.18 d; I(beta)+ = 25%). The thick target yield of 124I amounts to 81 MBq/microA h and the level of 125I-impurity to 0.9%. The 125Te(p,2n)124I reaction gives 124I yield about four times higher than the commonly used 124Te(p,n)124I and 124Te(d,2n)124I reactions. The proposed production energy range is too high for small cyclotrons but large quantities of 124I can be produced with medium-sized commercial machines.

  18. Biomimetic Hydroxyapatite Growth on Functionalized Surfaces of Ti-6Al-4V and Ti-Zr-Nb Alloys.

    Science.gov (United States)

    Pylypchuk, Ie V; Petranovskaya, A L; Gorbyk, P P; Korduban, A M; Markovsky, P E; Ivasishin, O M

    2015-12-01

    A biomimetic approach for coating titanium-containing alloys with hydroxyapatite (HA) is reported in the article. Two types of Ti-containing alloys were chosen as an object for coating: Ti-6Al-4V (recommended for orthopedic application) and a novel highly biocompatible Ti-Zr-Nb alloy, with good mechanical compatibility due to a modulus that is more close to that of human bones (E ≈ 50 GPa instead of 110 GPa in Ti-6Al-4V). Coating process was carried out in a 10×-concentrated simulated body fluid (SBF)-synthetic analog of human body plasma. The effect of oxidized and carboxylated alloy surface on formation of biomimetic hydroxyapatite has been studied. By XRD, we found influence of thermal conditions on HA crystal formation and size. SEM images and Fourier transform infrared confirmed that hydroxyapatite with different morphology, crystallinity, and Ca/P ratio formed on metallic surfaces. X-ray photoelectron spectroscopy showed that in the Ti-6AL-4V sample the observed Ca/P ratio reach 0.97, whereas in the Ti-Zr-Nb sample the observed Ca/P ratio reach 1.15.

  19. Renormalization of Optical Excitations in Molecules near a Metal Surface

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Thygesen, Kristian Sommer

    2011-01-01

    The lowest electronic excitations of benzene and a set of donor-acceptor molecular complexes are calculated for the gas phase and on the Al(111) surface using the many-body Bethe-Salpeter equation. The energy of the charge-transfer excitations obtained for the gas phase complexes are found to be ...

  20. Role of ribose in the initial excited state structural dynamics of thymidine in water solution: a resonance Raman and density functional theory investigation.

    Science.gov (United States)

    Zhu, Xin-Ming; Wang, Hui-gang; Zheng, Xuming; Phillips, David Lee

    2008-12-11

    Resonance Raman spectra were obtained for thymidine and thymine with excitation wavelengths in resonance with the approximately 260 nm band absorption spectrum. The spectra indicate that the Franck-Condon (FC) region photodissociation dynamics of thymidine have multidimensional character with motion predominantly along the nominal C5=C6 stretch + C6-H bend nu17 (delta = 0.75, lambda = 468 cm(-1)), the nominal thymine ring stretch + C6-H bend + N1-C1, stretch nu29 (delta = 0.73, lambda = 363 cm(-1)), the nominal thymine ring stretch + C5-CH3/ N1-C1, stretch nu37 (delta = 0.69, lambda = 292 cm(-1)), and accompanied by the moderate and minor changes in the nu40, nu20 and nu23, nu55, nu60, nu61, nu63 modes. A preliminary resonance Raman intensity analysis was done, and these results for thymidine and thymine were compared to each other. The roles of ribose in the FC structure dynamics of thymidine were explored and the results were used to correlate to its lifetime constants tau1 and tau2 for two nonradiative decay channels. Spi/Sn conical intersection versus a distorted structure of Spi,min in the FC region was briefly discussed.

  1. New Modes of Nuclear Excitations

    CERN Document Server

    Tsoneva, Nadia

    2014-01-01

    We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. The fine structure of nuclear electric and magnetic response functions is analyzed and compared to experimental data. Their relevance to nuclear astrophysics is discussed.

  2. Quantum kink and its excitations

    CERN Document Server

    Rajantie, Arttu

    2009-01-01

    We show how detailed properties of a kink in quantum field theory can be extracted from field correlation functions. This makes it possible to study quantum kinks in a fully non-perturbative way using Monte Carlo simulations. We demonstrate this by calculating the kink mass as well as the spectrum and approximate wave functions of its excitations. This way of measuring the kink mass has clear advantages over the existing approaches based on creation and annihilation operators or the kink free energy. Our methods are straightforward to generalise to more realistic theories and other defect types.

  3. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    Science.gov (United States)

    2013-02-01

    produce results on precipitation hardened Al alloys which provide a good indicator of long term field exposure performance in natural environments [15...I \\ I I i i I i i i I 750 ZOO AI-0.15Cu-0.9Mg-0.6Si (wt%) J50 m 100 10000 1000 10000 100000 1000000 i 10o Time, min Time...for good corrosion resistance and simultaneous weld penetration to achieve bonding vi. Designed New Braze alloy based on combined metallurgical

  4. Green functions and Langevin equations for nonlinear diffusion equations: A comment on ‘Markov processes, Hurst exponents, and nonlinear diffusion equations’ by Bassler et al.

    Science.gov (United States)

    Frank, T. D.

    2008-02-01

    We discuss two central claims made in the study by Bassler et al. [K.E. Bassler, G.H. Gunaratne, J.L. McCauley, Physica A 369 (2006) 343]. Bassler et al. claimed that Green functions and Langevin equations cannot be defined for nonlinear diffusion equations. In addition, they claimed that nonlinear diffusion equations are linear partial differential equations disguised as nonlinear ones. We review bottom-up and top-down approaches that have been used in the literature to derive Green functions for nonlinear diffusion equations and, in doing so, show that the first claim needs to be revised. We show that the second claim as well needs to be revised. To this end, we point out similarities and differences between non-autonomous linear Fokker-Planck equations and autonomous nonlinear Fokker-Planck equations. In this context, we raise the question whether Bassler et al.’s approach to financial markets is physically plausible because it necessitates the introduction of external traders and causes. Such external entities can easily be eliminated when taking self-organization principles and concepts of nonextensive thermostatistics into account and modeling financial processes by means of nonlinear Fokker-Planck equations.

  5. A convenient alumination of functionalized aromatics by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl.

    Science.gov (United States)

    Unsinn, Andreas; Wunderlich, Stefan H; Jana, Anukul; Karaghiosoff, Konstantin; Knochel, Paul

    2013-10-18

    A straightforward and efficient alumination of functionalized arenes by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl (TMP=2,2,6,6-tetramethylpiperidyl) has been developed. In particular, halogenated electron-rich aromatics can be smoothly functionalized by using the frustrated Lewis pair Et3 Al and TMPMgCl⋅LiCl. Compared with previously described alumination methods, this procedure avoids extensive cooling and the need for an excess of base. This in situ procedure has proven to be most practical and allows for regio- and chemoselective metalation of a wide range of aromatics with sensitive functional groups (CONEt2 , CO2 Me, CN, OCONMe2 ) or halogens (F, Cl, Br, I). The resulting aromatic aluminates, which were characterized by using NMR spectroscopy, were subjected to allylations, acylations, and palladium-catalyzed cross-coupling reactions after transmetalation to zinc. It was shown that the nature of the Zn salt used for transmetalation is crucial. Thus, compared with ZnCl2 (2 equiv), the use of Zn(OPiv)2 (2 equiv; OPiv=pivalate) allows the subsequent quenching reactions to be performed with only a slight excess of electrophile (1.2 equiv) and provides interesting functionalized aromatics in good yields.

  6. Relative excitation of the seismic shear waves Sn and Lg as a function of source depth and their propagation from Melanesia and Banda arcs to Australia

    Directory of Open Access Journals (Sweden)

    J. OLIVER

    1977-06-01

    Full Text Available SUMMARY. - Seismic activity associated with the collision of the continental
    part of the Australian plate with the oceanic Melanesian arcs along Papua New
    Guinea and the Banda arc provides an unusual opportunity to study the relative
    excitation of the seismic shear waves Sn and Lg. These waves are produced by
    earthquakes located along the arcs in the upper 200 km of the earth and are
    recorded by the Australian WWSSN Stations at Charters Towers (CTA and Alice
    Springs (ASP. The paths to these stations are predominantly continental. The data
    clearly show that for events located at crustal depths, Lg is the predominant phase
    on the records and Sn is either absent or very weak. For events deeper than about
    50-70 km, Sn becomes the predominant phase on the records. These observations
    arc in qualitative agreement with the explanations of Sn and Lg as higher
    modes of surface waves, for the particle displacement amplitudes are maximum
    within the crust for Lg and maximum within the lid of the lithospheric mantle
    for Sn. The data suggest that either the crustal wave guide for Lg is more
    efficient than that for Sn, or that Lg is more easily excited than Sn. No clear
    Lg is observed from shallow earthquakes when the length of the segment of the
    path crossing oceanic structure is greater than about 200 km. Also, widespread
    Quaternary volcanism within the « stable » area of central Papua New Guinea
    to the south of the mobile belt does not seem to affect the efficient transmission
    of high-frequency (1 Hz shear energy.
    The paths from events located along the New Hebrides, Solomon, and New
    Britain arcs to Australia traverse oceanic structure, and no Lg is observed from
    these paths. The inefficient propagation of Sn along these paths from both
    shallow and intermediate-depth events can be explained as follows: 1 For
    the New Hebrides case, the

  7. Excited states 4

    CERN Document Server

    Lim, Edward C

    2013-01-01

    Excited States, Volume 4 is a collection of papers that deals with the excited states of molecular activity. One paper investigates the resonance Raman spectroscopy as the key to vibrational-electronic coupling. This paper reviews the basic theory of Raman scattering; it also explains the derivation of the Raman spectra, excitation profiles, and depolarization ratios for simple resonance systems. Another paper reviews the magnetic properties of triplet states, including the zero-field resonance techniques, the high-field experiments, and the spin Hamiltonian. This paper focuses on the magnetic

  8. Excitation energies from ensemble DFT

    Science.gov (United States)

    Borgoo, Alex; Teale, Andy M.; Helgaker, Trygve

    2015-12-01

    We study the evaluation of the Gross-Oliveira-Kohn expression for excitation energies E1-E0=ɛ1-ɛ0+∂E/xc,w[ρ] ∂w | ρ =ρ0. This expression gives the difference between an excitation energy E1 - E0 and the corresponding Kohn-Sham orbital energy difference ɛ1 - ɛ0 as a partial derivative of the exchange-correlation energy of an ensemble of states Exc,w[ρ]. Through Lieb maximisation, on input full-CI density functions, the exchange-correlation energy is evaluated accurately and the partial derivative is evaluated numerically using finite difference. The equality is studied numerically for different geometries of the H2 molecule and different ensemble weights. We explore the adiabatic connection for the ensemble exchange-correlation energy. The latter may prove useful when modelling the unknown weight dependence of the exchange-correlation energy.

  9. Tribocorrosion studies in centrifugally cast Al-matrix SiC{sub p}-reinforced functionally graded composites

    Energy Technology Data Exchange (ETDEWEB)

    Velhinho, A. [CENIMAT - Materials Research Centre, FCTUNL, Caparica (Portugal); DCM - Materials Science Dept., FCTUNL, Caparica (Portugal); Botas, J.D. [DCM - Materials Science Dept., FCTUNL, Caparica (Portugal); Ariza, E. [CIICS - Research Centre on Interfaces and Surfaces Performance, Univ. of Minho, Guimaraes (Portugal); Gomes, J.R.; Rocha, L.A. [CIICS - Research Centre on Interfaces and Surfaces Performance, Univ. of Minho, Guimaraes (Portugal); DEM - Mechanical Engineering Dept., Univ. of Minho, Guimaraes (Portugal)

    2004-07-01

    The present work reports results obtained from a series of preliminary experiments aiming at complementing the current knowledge about the wear behaviour of centrifugally-cast FGM Al/SiCp composites, through concurrent corrosion processes. Precursor MMC's were prepared by rheocasting, using 118.8 {mu}m SiC particles and an Al-10Si-2.2 Mg alloy. Those MMC's were then molten and centrifugally cast in order to produce cylindrical FGMMC's. Discs machined from the top surface of each sample were tested against nodular cast iron pins, using an inverted configuration pin-on-disc tribometer. Sliding tests took place at room temperature, over a 50000 m sliding distance, with a sliding speed of 0.3 m s{sup -1}, under a 5 N normal load; both dry-sliding and water-lubricated tests were performed. In order to elucidate the mechanisms involved, the wear coefficients were calculated for each condition, and the samples were subjected to morphological characterization via SEM/EDS. Concurrently, in the case of the water-lubrication tests, the corrosion potential of the tribological pair was monitored. The results obtained show an increase in material loss for the water-lubricated cases, although variations are registered depending on reinforcing particle volume fraction. At the same time, the open circuit potential response of the tribological pair may be correlated with the events of formation/destruction of the tribolayers. (orig.)

  10. An Investigation of Stylistic Features of Kashf al-Mahjoub on the Basis of Halliday Functional Grammar

    Directory of Open Access Journals (Sweden)

    fatemeh majidi

    2015-03-01

    Full Text Available In order to grasp the attitude of the writer and discover the semantic system of his mind as well as the dominant ideology of the text, this paper aims to investigate the stylistic features of Kashf al-Mahjoub based on the ideational and interpersonal metafunctions (in the Halliday grammar. The most important results of this study are as following: the center of attention in the discourse of Kashf al-Mahjoub is the God. He is present in a place to be defined as one of the issues of Sufism and, by defining him, the worlds, man and other things are also defined. Regarding the ideational metafunction, the text is mainly abstract. Such a kind of thinking and the relative discourse are congruent with Sufism system of evaluation and beliefs as wells as the doctrine of spiritualism. The text is more persuasive than imperative. Even in the expression of norms, high and absolute commanding is not used. To persuade the reader, the author employs argumentative, descriptive and explaining devices as well as declarative and interrogative moods. He uses subjunctive mood instead of imperative and draws on the Quran and hadith as evidence for fixing the discourse of Sufism. Benedictive mood dominates the text and one of the characteristics of this text is arousing of emotions. To facilitate and expedite the process of persuasion, the writer uses emotive moods. Dubitative has the lowest frequency whereas the certainty mood has notable frequency. Declarative mood has the highest frequency.

  11. Electronic Excited States of Tungsten(0) Arylisocyanides

    OpenAIRE

    2015-01-01

    W(CNAryl)_6 complexes containing 2,6-diisopropylphenyl isocyanide (CNdipp) are powerful photoreductants with strongly emissive long-lived excited states. These properties are enhanced upon appending another aryl ring, e.g., W(CNdippPh^(OMe)_2)_6; CNdippPh^(OMe)_2 = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide (Sattler et al. J. Am. Chem. Soc. 2015, 137, 1198−1205). Electronic transitions and low-lying excited states of these complexes were investigated by time-dependent density fun...

  12. 离心铸造Al-Fe-Si合金自生FGM的研究%In-situ Functionally Gradient Materials(FGM) of Al-Fe-Si Alloy by Centrifugal Casting

    Institute of Scientific and Technical Information of China (English)

    徐自立; 魏伯康; 林汉同

    2001-01-01

    对几种不同的Al-Fe-Si合金进行了离心铸造。试验表明,在离心力场下合金中的初生相发生径向移动,但不同尺寸形态的初生相移动的效果不同,同时引起元素浓度的不同变化。初生相分布及元素浓度的倾斜变化,将带来相关性能的梯度变化,形成一定意义下的梯度功能材料。%Some various Al-Fe-Si alloys by centrifugal casting was conducted. The results showed that under the centrifugal field, primary phase in alloy migrated along the radical direction but the migration effects of the primary phase with various sizes were different. Meanwhile, the element concentration has different variation under the centrifugal field. The sloping changes of the primary phase distribution and the element concentration would results in the gradient variation of relevant properties and form functionally gradient materials to certain extent.

  13. Excited cooper pairs

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Arrietea, M. G.; Solis, M. A.; De Llano, M. [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

    2001-02-01

    Excited cooper pairs formed in a many-fermion system are those with nonzero total center-of mass momentum (CMM). They are normally neglected in the standard Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity for being too few compared with zero CMM pairs. However, a Bose-Einstein condensation picture requires both zero and nonzero CMM pairs. Assuming a BCS model interaction between fermions we determine the populations for all CMM values of Cooper pairs by actually calculating the number of nonzero-CMM pairs relative to that of zero-CMM ones in both 2D and 3D. Although this ratio decreases rapidly with CMM, the number of Cooper pairs for any specific CMM less than the maximum (or breakup of the pair) momentum turns out to be typically larger than about 95% of those with zero-CMM at zero temperature T. Even at T {approx}100 K this fraction en 2D is still as large as about 70% for typical quasi-2D cuprate superconductor parameters. [Spanish] Los pares de cooper excitados formados en un sistema de muchos electrones, son aquellos con momentos de centro de masa (CMM) diferente de cero. Normalmente estos no son tomados en cuenta en la teoria estandar de la superconductividad de Bardeen-Cooper-Schrieffer (BCS) al suponer que su numero es muy pequeno comparados con los pares de centro de masa igual a cero. Sin embargo, un esquema de condensacion Bose-Einstein requiere de ambos pares, con CMM cero y diferente de cero. Asumiendo una interaccion modelo BCS entre los fermiones, determinamos la poblacion de pares cooper con cada uno de todos los posibles valores del CMM calculando el numero de pares con momentos de centro de masa diferente de cero relativo a los pares de CMM igual a cero, en 2D y 3D. Aunque esta razon decrece rapidamente con el CMM, el numero de pares de cooper para cualquier CMM especifico menor que el momento maximo (o rompimiento de par) es tipicamente mas grande que el 95% de aquellos con CMM cero. Aun a T {approx}100 K esta fraccion en 2D es

  14. Electron impact vibrational excitation of methyl chloride

    Science.gov (United States)

    Sakaamini, Ahmad; Hargreaves, Leigh; Khakoo, Murtadha

    2016-05-01

    Low energy differential cross sections and excitation functions for vibrational excitation of CH3 Cl are presented for five vibrational features in the electron energy loss spectrum of this molecule. Electron energies range from 1 eV to 15 eV and scattering angles from 10o to 125o. Results will be compared to existing data for CH3 Cl in the literature. Funded by a NSF-AMOP-RUI Grant.

  15. Computing Correct Truncated Excited State Wavefunctions

    CERN Document Server

    Bacalis, N C; Zang, J; Karaoulanis, D

    2016-01-01

    We demonstrate that, if a truncated expansion of a wave function is small, then the standard excited states computational method, of optimizing one root of a secular equation, may lead to an incorrect wave function - despite the correct energy according to the theorem of Hylleraas, Undheim and McDonald - whereas our proposed method [J. Comput. Meth. Sci. Eng. 8, 277 (2008)] (independent of orthogonality to lower lying approximants) leads to correct reliable small truncated wave functions. The demonstration is done in He excited states, using truncated series expansions in Hylleraas coordinates, as well as standard configuration-interaction truncated expansions.

  16. Conceptualizing the relations between metacognition and executive functions in Amyotrophic Lateral Sclerosis (ALS patients’ caregivers. A preliminary study

    Directory of Open Access Journals (Sweden)

    Stefania La Foresta

    2015-12-01

    Full Text Available Executive Functions are goal-directed neurocognitive processes that allow the management of cognition and behavior. Executive Functions are essential to allow people to set goals, self-monitor, inhibit inappropriate responses, and generally engage in well-planned, flexible, future-oriented behavior. Metacognitive processes, in close alliance with executive functions, are viewed as integral components of awareness and emotional regulation. The influence of metacognition on planning, monitoring and mental flexibility has not been investigated. The aim of this pilot study was to examine the relationship between metacognition and executive functions in Amyotrophic Lateral Sclerosis patient's caregivers. Twenty-two caregivers were evaluated using the following instruments: Metacognition Questionnaire-30 and Wisconsin Card Sorting Test. Data analysis was performed using SPSS for Windows applying correlational analysis (Spearman’s Rho. We founded that total score of metacognition is positive correlated with number of perseverative errors made in Wisconsin (0.75 p<.001. In particular, need to control thoughts is positive correlated with number of perseverative errors (0.78 p<.001. Results could suggest the importance to explore the relationship between metacognitive processes and executive functions in order to cope disease’s changes and optimize the relative daily living management. Providing care to a Amyotrophic Lateral Sclerosis relative may cause feelings of burden, psychological distress, anxiety or depression, in particular in case of dysfunctional metacognitions. So, our future researches will be oriented to explore the relationship between psycopatological symptoms and metacognition and executive functions in ALS’caregivers in order to contain caregiver emotional burden.

  17. Functional and biomechanic aspects of the scapular girdle and forelimbs of Unaysaurus tolentinoiLeal et al., 2004 (Saurischia: Sauropodomorpha)

    Science.gov (United States)

    Vargas-Peixoto, Dilson; Da-Rosa, Átila Augusto Stock; Gallo de França, Marco Aurélio

    2015-08-01

    This study presents evidence about the biomechanics and forelimbs functionality of the basal sauropodomorph Unaysaurus tolentinoi (upper portion of the SM2 sequence, Santa Maria Supersequence, Upper Triassic from southern Brazil). Maximum and minimum motion angles were inferred in the joints, disregarding the presence and/or thickness of cartilage. Furthermore, processes and external structures of the bones were analyzed in attributing the functionality of forelimbs. Unaysaurus tolentinoi had well-developed grapple ability. However, the preserved elements and their osteological features are not conclusive about strictly bipedalism or quadrupedalism in U. tolentinoi.

  18. Doping the Buckminsterfullerene by Substitution: Density Functional Theory Studies of C59X (X = B, N, Al, Si, P, Ga, Ge, and As

    Directory of Open Access Journals (Sweden)

    Hongcun Bai

    2013-01-01

    Full Text Available The heterofullerenes C59X (X = B, N, Al, Si, P, Ga, Ge, and As were investigated by quantum chemistry calculations based on density functional theory. These hybrid cages can be seen as doping the buckminsterfullerene by heteroatom substitution. The geometrical structures, relative stabilities, electronic properties, vibrational frequencies, dielectric constants, and aromaticities of the doped cages were studied systemically and compared with those of the pristine C60 cage. It is found that the doped cages with different heteroatoms exhibit various electronic, vibrational, and aromatic properties. These results imply the possibility to modulate the physical properties of these fullerene-based materials by tuning substitution elements.

  19. New measurements of excitation functions of 186W(p,x) nuclear reactions up to 65 MeV. Production of a 178W/178mTa generator

    Science.gov (United States)

    Tárkányi, F.; Ditrói, F.; Takács, S.; Hermanne, A.

    2017-01-01

    New experimental excitation functions for proton induced reactions on natW are presented in the 32-65 MeV energy range. The cross-sections for natW(p,xn)186,184m,184g,183, 182m,182g,181Re, natW(p,x)178W, natW(p,x)183,182, 180m, 177,176,175Ta, 175Hf and 177Lu were measured via an activation method by using a stacked-foil irradiation technique and high resolution gamma-ray spectroscopy. The results were compared with predicted values obtained with the nuclear reaction code TALYS (results taken from the TENDL 2014 and TENDL 2015 on-line libraries). Production routes of the medically relevant radionuclides 186Re, the 178W → 178Ta generator and 181W are discussed.

  20. Excitation function for deuteron induced nuclear reactions on natural ytterbium for production of high specific activity {sup 177g}Lu in no-carrier-added form for metabolic radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Manenti, Simone, E-mail: simone.manenti@mi.infn.i [LASA, Universita degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate (Italy); Groppi, Flavia; Gandini, Andrea; Gini, Luigi [LASA, Universita degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate (Italy); Abbas, Kamel; Holzwarth, Uwe; Simonelli, Federica [Institute for Health and Consumer Protection, Joint Research Centre, European Commission, TP 500, I-21020 Ispra (Italy); Bonardi, Mauro, E-mail: mauro.bonardi@mi.infn.i [LASA, Universita degli Studi di Milano and INFN-Milano, via F.lli Cervi 201, I-20090 Segrate (Italy)

    2011-01-15

    Deuteron-induced nuclear reactions for generation of no-carrier-added Lu radionuclides were investigated using the stacked-foil activation technique on natural Yb targets at energies up to E{sub d}=18.18 MeV. Excitation functions of the reactions {sup nat}Yb(d,xn){sup 169,170,171,172,173,174g,174m,176m,177g}Lu and {sup nat}Yb(d,pxn){sup 169,175,177}Yb have been measured, among them three ({sup 169}Lu, {sup 174m}Lu and {sup 176m}Lu) are reported for the first time. The upper limit of the contamination from the long-lived metastable level {sup 177m}Lu was evaluated too. Thick-target yields for all investigated radionuclides are calculated.

  1. Excitation function of squared speed-of-sound extracted from (net-)proton rapidity spectra in Au-Au and Pb-Pb collisions over an energy range from AGS to RHIC

    CERN Document Server

    Gao, Li-Na; Sun, Yan; Sun, Zhu; Lacey, Roy A

    2016-01-01

    Experimental results of the rapidity distributions of protons and net-protons (protons minus antiprotons) emitted in gold-gold (Au-Au) and lead-lead (Pb-Pb) collisions, measured by a few collaborations at the alternating gradient synchrotron (AGS), super proton synchrotron (SPS), and relativistic heavy ion collider (RHIC), are described by a revised Landau hydrodynamic model. The values of squared speed-of-sound parameter $c^2_s$ are then extracted from the rapidity distribution widths of (net-)protons. The excitation function of $c^2_s$ of the interacting system in Au-Au and Pb-Pb collisions over an energy range from AGS to RHIC is obtained to show a local minimum or softest point in the equation of state (EoS) at the center-of-mass energy per nucleon pair $\\sqrt{s_{NN}}=8.8$ GeV which confirms our previous result.

  2. Excitation functions of 124Te(d,xn)124,125I reactions from threshold up to 14 MeV: comparative evaluation of nuclear routes for the production of 124I.

    Science.gov (United States)

    Bastian, T H; Coenen, H H; Qaim, S M

    2001-09-01

    Excitation functions of the nuclear reactions 124Te(d,xn)124-125I were measured from their respective thresholds up to 14.0 MeV via the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 99.8% enriched 124Te on Ti-backing. The excitation function of the 124Te(d,n)125I reaction was measured for the first time. The present data for the 124Te(d,2n)124I reaction are by an order of magnitude higher than the literature experimental data but are in good agreement with the results of a hybrid model calculation. From the measured cross sections, integral yields of 124,125I were calculated. The energy range Ed = 14 --> 10 MeV appears to be the best compromise between 124I-yield and 1251-impurity. The calculated 124I-yield amounts to 17.5 MBq/microA h and the 125I-impurity to 1.7%. A critical evaluation of the three nuclear routes for the production of 124I, viz. 124Te(d,2n)-, 124Te(p,n)- and 125Te(p,2n)-processes, is given. The reaction studied in this work proved to be least suitable. The 124Te(p,n)-reaction gives 124I of the highest radionuclidic purity, and a small-sized cyclotron is adequate for production purposes. The 125Te(p,2n)-reaction is more suitable at a medium-sized cyclotron: the yield of 124I is four times higher than in the other two reactions but the level of 0.9% 125I-impurity is relatively high.

  3. Structural and electronic properties of SrAl{sub 2}O{sub 4}:Eu{sup 2+} from density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Nazarov, M. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Institute of Applied Physics, Academiei Street 5, Chisinau MD-2028 (Moldova, Republic of); Brik, M.G., E-mail: brik@fi.tartu.ee [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Spassky, D. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Skobeltsyn Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, 119991 Moscow (Russian Federation); Tsukerblat, B. [Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Nor Nazida, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Faculty of Art and Design, Universiti Teknologi MARA (Perak), Seri Iskandar, 32610 Bandar Baru Seri Iskandar, Perak (Malaysia); Ahmad-Fauzi, M.N. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia)

    2013-10-05

    Highlights: •Persistent phosphor SrAl{sub 2}O{sub 4}:Eu{sup 2+} was synthesized and studied. •Ab initio calculations of its electronic properties were performed. •Lowest position of the Eu 4f states in the band gap was determined. •Position of the Eu 4f states agrees with the charge transfer transition. -- Abstract: A stoichiometric micro-sized powder SrAl{sub 2}O{sub 4}:Eu{sup 2+} was synthesized by traditional solid state reaction at 1250 °C. Low-temperature spectroscopic measurements revealed two luminescence bands at 450 nm and 512 nm; their origin was discussed. Theoretical calculations of the structural and optical properties of SrAl{sub 2}O{sub 4}:Eu{sup 2+} in the framework of the density functional theory (DFT) were carried out; the obtained results were compared with the corresponding experimental data. For the first time, the position of the lowest 4f states of Eu in the host’s band gap was calculated for both available Sr positions to be at about 4.5–5 eV above the top of the valence band. Reliability of this result is confirmed by good agreement with the experimental value of the O(2p)–Eu(4f) charge transfer energy, which is equal to about 4.9 eV.

  4. Electrochemical sensor for bisphenol A based on ionic liquid functionalized Zn-Al layered double hydroxide modified electrode.

    Science.gov (United States)

    Zhan, Tianrong; Song, Yang; Li, Xianjun; Hou, Wanguo

    2016-07-01

    The plate-like Zn-Al layered double hydroxide modified with 1-aminopropyl-3-methylimidzaolium tetrafluoroborate (named as ILs-LDH) was synthesized by coprecipitation method. Several techniques confirmed the layered structure of ILs-LDH with a disk-like morphology. A novel electrochemical sensor based on ILs-LDH modified glass carbon electrode (GCE) was developed for bisphenol A (BPA) determination. Experimental factors including modified content, pH, scan rate, accumulation time and potential had been carefully optimized. ILs-LDH/GCE performed the excellent electro-oxidation ability toward BPA with the more negative oxidation overpotential and larger peak current than bare GCE or LDH/GCE. Differential pulse voltammetry determination of BPA afforded a wider linear range from 0.02 to 3μM with the detection limit of 4.6nM (S/N=3). The fabricated sensor demonstrated an acceptable reproducibility, good stability and high sensitivity. The proposed method was successfully used to detect BPA in real water samples with satisfactory recovery ranging from 94.9% to 102.0%.

  5. AL Amyloidosis

    Directory of Open Access Journals (Sweden)

    Desport Estelle

    2012-08-01

    Full Text Available Abstract 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

  6. Schizophrenia as a disconnection syndrome. Studies with functional magnetic resonance imaging and structural equation modeling; Schizophrenie als Diskonnektionssyndrom. Studien mit funktioneller Magnetresonanztomographie und Strukturgleichungsmodellen

    Energy Technology Data Exchange (ETDEWEB)

    Schloesser, R. [Universitaet Jena, Psychiatrische Klinik (Germany); Universitaet Jena, Psychiatrische Klinik, Jena (Germany); Wagner, G.; Koehler, S.; Sauer, H. [Universitaet Jena, Psychiatrische Klinik (Germany)

    2005-02-01

    Aside from characteristic psychopathological symptoms, cognitive deficits are a core feature of schizophrenia. These deficits can only be addressed within the context of widespread functional interactions among different brain areas. To examine these interactions, structural equation modeling (SEM) was used for the analysis of fMRI datasets. In a series of studies, both in antipsychotic-treated and drug-free schizophrenic patients, a pattern of enhanced thalamocortical functional connectivity could be observed as an indicator for possible disruptions of frontostriatal thalamocortical circuitry. Moreover, drug-free patients and those receiving typical antipsychotic drugs were characterized by reduced interhemispheric corticocortical connectivity. This difference relative to normal controls was less in patients under atypical antipsychotic drugs. The results could be interpreted as a beneficial effect of atypical antipsychotic drugs on information processing in schizophrenic patients. The present findings are consistent with the model of schizophrenia as a disconnection syndrome and earlier concepts of ''cognitive dysmetria'' in schizophrenia. (orig.) [German] Neben der charakteristischen psychopathologischen Symptomatik stellen kognitive Defizite ein zentrales Merkmal der Schizophrenie dar. Diese Defizite koennen nur im Kontext miteinander interagierender Hirnareale verstanden werden. Zur Untersuchung dieser funktionellen Wechselbeziehungen wurden Strukturgleichungsmodelle (''structural equation modeling'', SEM) zur Auswertung von fMRT-Datensaetzen verwendet. In einer Untersuchungsreihe bei schizophrenen Patienten ergab sich sowohl bei antipsychotisch behandelten als auch bei unbehandelten Patienten ein Muster gesteigerter thalamokortikaler funktioneller Konnektivitaet als Hinweis auf eine moegliche Stoerung fronto-striato-thalamo-kortikaler Regelkreise. Unbehandelte Patienten und Patienten unter typischen Antipsychotika

  7. Atomic data from the iron project. 3: Rate coefficients for electron impact excitation of boron-like ions: Ne VI, Mg VIII, Al IX, Si X, S XII, Ar XIV, Ca XVI and Fe XXII

    Science.gov (United States)

    Zhang, Hong Lin; Graziani, Mark; Pradhan, Anil K.

    1994-01-01

    Collison strengths and maxwellian averaged rate coefficients have been calculated for the 105 transitions among all 15 fine structure levels of the 8 LS terms 2s(sup 2) 2 P(P-2(sup 0 sub 1/, 3/2)), 2s2p(sup 2)(P-4(sub 1/2,3/2,5/2), D-2(sub 3/2, 5/2), S-2(sub 1/2), P-2(sub 1/2, 3/2)), 2p(sup 3)(S-4(sup 0)(sub 3/2), D-2(sup 0 sub 3/2, 5/2), P-2(sup 0 sub 1/2, 3/2)) in highly- charged B-like Ne, Mg, Al, Si, S, Ar, Ca and Fe. Rate coefficients have been tabulated at a wide range of temperatures, depending on the ion charge and abundance in plasma sources. Earlier work for O IV has also been extended to include the high temperature range. A brief discussion of the calculations, sample results, and comparison with earlier works is also given. While much of the new data should be applicable to UV spectral diagnostics, the new rates for the important ground state fine structure transition P-2(sup 0 sub 1/2)-P-2(sup 0 sub 3/2) should result in significant revision of the IR cooling rates in plasmas where B-like ions are prominent constituents, since the new rate coefficients are generally higher by several factors compared with the older data.

  8. ENERGY-LOSS FUNCTIONS DERIVED FROM REELS SPECTRA FOR ALUMINUM

    Institute of Scientific and Technical Information of China (English)

    Z.M. Zhang; Z.J. Ding; H.M. Li; K. Salma; X. Sun; R. Shimizu; T. Koshikawa; K. Goto

    2005-01-01

    The effective energy loss functions for Al have been derived from differential inverse inelastic mean free path based on the extended Landau approach. It has been revealed that the effective energy loss function is very close in value to the theoretical surface energy loss function in the lower energy loss region but gradually approaches the theoretical bulk energy loss function in the higher energy loss region. Moreover, the intensity corresponding to surface excitation in effective energy loss functions decreases with the increase of primary electron energy. These facts show that the present effective energy loss function describes not only surface excitation but also bulk excitation. At last, REELS spectra simulated by Monte Carlo method based on use of the effective energy loss functions has reproduced the experimental REELS spectra with considerable success.

  9. Linear-scaling density-functional simulations of charged point defects in Al2O3 using hierarchical sparse matrix algebra.

    Science.gov (United States)

    Hine, N D M; Haynes, P D; Mostofi, A A; Payne, M C

    2010-09-21

    We present calculations of formation energies of defects in an ionic solid (Al(2)O(3)) extrapolated to the dilute limit, corresponding to a simulation cell of infinite size. The large-scale calculations required for this extrapolation are enabled by developments in the approach to parallel sparse matrix algebra operations, which are central to linear-scaling density-functional theory calculations. The computational cost of manipulating sparse matrices, whose sizes are determined by the large number of basis functions present, is greatly improved with this new approach. We present details of the sparse algebra scheme implemented in the ONETEP code using hierarchical sparsity patterns, and demonstrate its use in calculations on a wide range of systems, involving thousands of atoms on hundreds to thousands of parallel processes.

  10. Quasiparticle excitations in frustrated antiferromagnets

    Energy Technology Data Exchange (ETDEWEB)

    Trumper, Adolfo E. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina)]. E-mail: trumper@ifir.edu.ar; Gazza, Claudio J. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina); Manuel, Luis O. [Instituto de Fisica Rosario (CONICET) Universidad Nacional de Rosario, Boulevard 27 de Febrero 210 bis, 2000 Rosario (Argentina)]. E-mail: manuel@ifir.edu.ar

    2004-12-31

    We have computed the quasiparticle wave function corresponding to a hole injected in a triangular antiferromagnet. We have taken into account multi-magnon contributions within the self-consistent Born approximation. We have found qualitative differences, under sign reversal of the integral transfer t, regarding the multi-magnon components and the own existence of the quasiparticle excitations. Such differences are due to the subtle interplay between magnon-assisted and free hopping mechanisms. We conclude that the conventional quasiparticle picture can be broken by geometrical frustration without invoking spin liquid phases.

  11. The density functional study of electronic structure, electronic charge density, linear and nonlinear optical properties of single crystal alpha-LiAlTe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Khan, Wilayat, E-mail: walayat76@gmail.com [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

    2014-04-01

    Highlights: • FP-LAPW technique is used for calculating the electronic structure. • The band structure shows that the calculated compound is semiconductor. • The complex dielectric function has been calculated. • Nonlinear optical properties has also been calculated. • This compound can be used for molecular engineering of the crystals. - Abstract: Self-consistent calculations is performed using the full potential linear augmented plane wave (FP-LAPW) technique based on density functional theory (DFT) to investigate the electronic band structure, density of states, electronic charge density, linear and non-linear optical properties of α-LiAlTe{sub 2} compound having tetragonal symmetry with space group I4{sup ¯}2d. The electronic structure are calculated using the Ceperley Alder local density approach (CA-LDA), Perdew Burke and Ernzerhof generalize gradient approach (PBE-GGA), Engel–Vosko generalize gradient approach (EVGGA) and modified Becke Johnson approach (mBJ). Band structure calculations of (α-LiAlTe{sub 2}) depict semiconducting nature with direct band gap of 2.35 eV (LDA), 2.48 eV (GGA), 3.05 eV (EVGGA) and 3.13 eV (mBJ), which is comparable to experimental value. The calculated electronic charge density show ionic interaction between Te and Li atoms and polar covalent interaction between Al and Te atoms. Some optical susceptibilities like dielectric constants, refractive index, extension co-efficient, reflectivity and energy loss function have been calculated and analyzed on the basis of electronic structure. The compound α-LiAlTe{sub 2} provides a considerable negative value of birefringence of −0.01. Any anisotropy observed in the linear optical properties which are in favor to enhance the nonlinear optical properties. The symbol χ{sub abc}{sup (2)}(ω) represents the second order nonlinear optical susceptibilities, possess six non-zero components in this symmetry (tetragonal), called: 1 2 3, 2 1 3, 2 3 1, 1 3 2, 3 1 2 and 3 2 1

  12. The DSS-14 C-band exciter

    Science.gov (United States)

    Rowan, D. R.

    1989-01-01

    The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

  13. Hydrogen Bonds in Excited State Proton Transfer

    Science.gov (United States)

    Horke, D. A.; Watts, H. M.; Smith, A. D.; Jager, E.; Springate, E.; Alexander, O.; Cacho, C.; Chapman, R. T.; Minns, R. S.

    2016-10-01

    Hydrogen bonding interactions between biological chromophores and their surrounding protein and solvent environment significantly affect the photochemical pathways of the chromophore and its biological function. A common first step in the dynamics of these systems is excited state proton transfer between the noncovalently bound molecules, which stabilizes the system against dissociation and principally alters relaxation pathways. Despite such fundamental importance, studying excited state proton transfer across a hydrogen bond has proven difficult, leaving uncertainties about the mechanism. Through time-resolved photoelectron imaging measurements, we demonstrate how the addition of a single hydrogen bond and the opening of an excited state proton transfer channel dramatically changes the outcome of a photochemical reaction, from rapid dissociation in the isolated chromophore to efficient stabilization and ground state recovery in the hydrogen bonded case, and uncover the mechanism of excited state proton transfer at a hydrogen bond, which follows sequential hydrogen and charge transfer processes.

  14. Self-excitation of space charge waves

    DEFF Research Database (Denmark)

    Lyuksyutov, Sergei; Buchhave, Preben; Vasnetsov, Mikhail

    1997-01-01

    We report a direct observation of space charge waves in photorefractive crystals with point group 23 (sillenites) based on their penetration into an area with uniform light illumination. It is shown experimentally that the quality factor of the waves increases substantially with respect to what c...... current theory predicts [B. Sturman el al., Appl. Phys. A 55, 235 (1992)]. This results in the appearance of strong spontaneous beams caused by space charge wave self-excitation....

  15. Population of highly excited intermediate resonance states by electron transfer and excitation

    Energy Technology Data Exchange (ETDEWEB)

    Schuch, R. (Manne Siegbahn Institute of Physics, S-104 05 Stockholm, Sweden (SE)); Justiniano, E. (Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353 (USA)); Schulz, M.; Datz, S.; Dittner, P.F.; Giese, J.P.; Krause, H.F.; Schoene, H.; Vane, R. (Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6377 (USA)); Shafroth, S. (Department of Physics, North Carolina University, Chapel Hill, North Carolina 27599-3255 (USA))

    1991-05-01

    Coincidences between two sulfur {ital K} x rays were detected from collisions of hydrogenlike S ions with H{sub 2} gas in the projectile energy range between 150 and 225 MeV. These {ital K} x rays are emitted in the decay of doubly excited states formed in the collisions via transfer and excitation. The excitation function for two coincident {ital K}{beta} transitions peaks at about 175 MeV, slightly above the expected {ital KMM} resonance energy for resonant transfer and excitation (RTE). This demonstrates the occurrence of {Delta}{ital N}{ge}2 transitions (i.e., {ital KMM} and higher resonances) in the RTE process. The cross sections for the population of the very highly excited states are higher than those predicted by theoretical calculations that use dielectronic recombination rates folded with the Compton profile for the bound electrons.

  16. Hardness and excitation energy

    Indian Academy of Sciences (India)

    Á Nagy

    2005-09-01

    The concept of the ensemble Kohn-Sham hardness is introduced. It is shown that the first excitation energy can be given by the Kohn-Sham hardness (i.e. the energy difference of the ground-state lowest unoccupied and highest occupied levels) plus an extra term coming from the partial derivative of the ensemble exchange-correlation energy with respect to the weighting factor in the limit → 0. It is proposed that the first excitation energy can be used as a reactivity index instead of the hardness.

  17. Excitation Methods for Bridge Structures

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

    1999-02-08

    This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

  18. Elastic modulus of Al-Si/SiC metal matrix composites as a function of volume fraction

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh Kumar, S; Rajasekharan, T [Powder Metallurgy Group, Defence Metallurgical Research Laboratory, Kanchanbagh PO, Hyderabad-500 058 (India); Seshu Bai, V [School of Physics, University of Hyderabad, Central University PO, Hyderabad-500 046 (India); Rajkumar, K V; Sharma, G K; Jayakumar, T, E-mail: dearsanthosh@gmail.co [Non-Destructive Evaluation Division, Indira Gandhi Center for Atomic Research, Kalpakkam, Chennai-603 102 (India)

    2009-09-07

    Aluminum alloy matrix composites have emerged as candidate materials for electronic packaging applications in the field of aerospace semiconductor electronics. Composites prepared by the pressureless infiltration technique with high volume fractions in the range 0.41-0.70 were studied using ultrasonic velocity measurements. For different volume fractions of SiC, the longitudinal velocity and shear velocity were found to be in the range of 7600-9300 m s{sup -1} and 4400-5500 m s{sup -1}, respectively. The elastic moduli of the composites were determined from ultrasonic velocities and were analysed as a function of the volume fraction of the reinforcement. The observed variation is discussed in the context of existing theoretical models for the effective elastic moduli of two-phase systems.

  19. CuAl{sub 1-x}In{sub x}Se{sub 2} solid solutions: Dielectric function and inter-band optical transitions

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Yong Gu [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka 599-8531 (Japan)], E-mail: shim@pe.osakafu-u.ac.jp; Hasegawa, Kouji [Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka 599-8531 (Japan); Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan); Mamedov, Nazim [Institute of Physics, National Academy of Sciences of Azerbaijan, Javid ave. 33, Baku, AZ-1143 (Azerbaijan)

    2008-12-31

    The dielectric function of bulk CuAl{sub 1-x}In{sub x}Se{sub 2} with composition x varying from x = 0.07 to x = 0.6 were studied over the photon energy region 1.0-6.0 eV at room temperature by spectroscopic ellipsometry. Information on the inter-band optical transitions was obtained from the results of the standard critical point analysis of the obtained dielectric function. With increasing Indium content, all spectral features of the obtained dielectric functions were found to gradually shift towards lower energies. The details of this shift for each critical point retrieved from the obtained dielectric function were disclosed. A compositional dependence of the optical transitions in {gamma} point of the Brillouin zone was verified to be strong. Such dependence for N and T points turned out to be weak by comparison. The later fact was accounted for a small compositional shift of the conduction band states in N and T points as compared to {gamma} point.

  20. First generation TREN dendrimers functionalized with naphthyl and/or dansyl units. Ground and excited state electronic interactions and protonation effects.

    Science.gov (United States)

    Passaniti, Paolo; Maestri, Mauro; Ceroni, Paola; Bergamini, Giacomo; Vögtle, Fritz; Fakhrnabavi, Hassan; Lukin, Oleg

    2007-04-01

    We report the photophysical properties (absorption and emission spectra, quantum yield, and lifetime) of five dendrimers of first generation based on a TREN (tris(2-aminoethyl)amine) skeleton functionalized at the periphery with naphthyl and/or 5-dimethylamino-1-naphthalenesulfonamide (hereafter called dansyl) chromophores. Each dendrimer comprises one tertiary amine unit in the core and three branches carrying a sulfonimido unit at the periphery, each one substituted by two identical or different moieties. In particular, TD6 and TN6 contain dansyl (D) or naphthyl (N) units, respectively, while TD3B3, TN3B3 and TN3D3 contain dansyl, naphthyl or benzyl (B) units at the periphery. The spectroscopic behaviour of these dendrimers has been investigated in acetonitrile solution and compared with that of reference compounds. For all dendrimers the absorption bands are red shifted compared to those of monomeric naphthyl and dansyl reference compounds. Moreover, the intense naphthyl and dansyl fluorescence is greatly quenched because of strong interactions between the two aromatic moieties linked by a sulfonimido unit. Protonation of the amine units of the dendrimers by addition of CF(3)SO(3)H (triflic) acid causes a decrease in intensity of the luminescence and a change in the shape of the emission bands. The shapes of the titration curves depend on the dendrimer, but in any case the effect of acid can be fully reversed by successive addition of base (tributylamine). The obtained results reveal that among the intradendrimer interactions the most important one is that taking place (via mesomeric interaction) between the various chromophores and a pair of sulfonimido groups.

  1. Proton-impact excitation of helium to the n = 2 sublevels in the distorted-wave Born approximation

    Science.gov (United States)

    Khurana, I.; Srivastava, R.; Tripathi, A. N.

    1986-05-01

    Differential and total cross sections for proton-impact excitation of helium to the n = 2 sublevels are calculated in the distorted-wave Born approximation. Many-parameter correlated wave functions are used to describe the helium atom. A comparison with recent theories and experimental measurements is made. The present calculations for differential cross sections for the n = 2 substates yield good agreement with the measured values of Park et al. (1978) and Kvale et al. (1985) and the multistate eikonal calculations of Flannery and McCann (1974).

  2. Positron excitation of neon

    Science.gov (United States)

    Parcell, L. A.; Mceachran, R. P.; Stauffer, A. D.

    1990-01-01

    The differential and total cross section for the excitation of the 3s1P10 and 3p1P1 states of neon by positron impact were calculated using a distorted-wave approximation. The results agree well with experimental conclusions.

  3. Excitation of Stellar Pulsations

    DEFF Research Database (Denmark)

    Houdek, G.

    2012-01-01

    In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

  4. Decoherence at constant excitation

    Science.gov (United States)

    Torres, J. M.; Sadurní, E.; Seligman, T. H.

    2012-02-01

    We present a simple exactly solvable extension of the Jaynes-Cummings model by adding dissipation. This is done such that the total number of excitations is conserved. The Liouville operator in the resulting master equation can be reduced to blocks of 4×4 matrices.

  5. Decoherence at constant excitation

    CERN Document Server

    Torres, Juan Mauricio; Seligman, Thomas H

    2011-01-01

    We present a simple exactly solvable extension of of the Jaynes-Cummings model by adding dissipation. This is done such that the total number of excitations is conserved. The Liouville operator in the resulting master equation can be reduced to blocks of $4\\times 4$ matrices.

  6. Fuzzballs with internal excitations

    Energy Technology Data Exchange (ETDEWEB)

    Kanitscheider, Ingmar; Skenderis, Kostas; Taylor, Marika [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018XE Amsterdam (Netherlands)

    2007-06-15

    We construct general 2-charge D1-D5 horizon-free non-singular solutions of IIB supergravity on T{sup 4} and K3 describing fuzzballs with excitations in the internal manifold; these excitations are characterized by arbitrary curves. The solutions are obtained via dualities from F1-P solutions of heterotic and type IIB on T{sup 4} for the K3 and T{sup 4} cases, respectively. We compute the holographic data encoded in these solutions, and show that the internal excitations are captured by vevs of chiral primaries associated with the middle cohomology of T{sup 4} or K3. We argue that each geometry is dual to a specific superposition of R ground states determined in terms of the Fourier coefficients of the curves defining the supergravity solution. We compute vevs of chiral primaries associated with the middle cohomology and show that they indeed acquire vevs in the superpositions corresponding to fuzzballs with internal excitations, in accordance with the holographic results. We also address the question of whether the fuzzball program can be implemented consistently within supergravity.

  7. Role of two-electron processes in the excitation-ionization of lithium atoms by fast ion impact

    CERN Document Server

    Kirchner, T; Gulyás, L

    2015-01-01

    We study excitation and ionization in the 1.5 MeV/amu O$^{8+}$-Li collision system, which was the subject of a recent reaction-microscope-type experiment [Fischer \\textit{et al.}, Phys. Rev. Lett. \\textbf{109}, 113202 (2012)]. Starting from an independent-electron model based on determinantal wave functions and using single-electron basis generator method and continuum distorted-wave with eikonal initial-state calculations we show that pure single ionization of a lithium $K$-shell electron is too weak a process to explain the measured single differential cross section. Rather, our analysis suggests that two-electron excitation-ionization processes occur and have to be taken into account when comparing with the data. Good agreement is obtained only if we replace the independent-electron calculation by an independent-event model for one of the excitation-ionization processes and also take a shake-off process into account.

  8. Excitation functions and yields of proton induced reactions at intermediate energies leading to important diagnostics radioisotopes of {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl

    Energy Technology Data Exchange (ETDEWEB)

    Rurarz, E. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)

    1994-12-31

    This report describes investigations of the excitation functions of the proton induced reactions on 14 targets (Mn, Co, Br, Rb, {sup 99}Tc, {sup 113}Cd, {sup 114}Cd, Cd, I, Cs, Ta, {sup 206,207,208}Pb) leading directly or indirectly to the formation of radionuclides {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 97}Ru, {sup 111}In, {sup 123}I, {sup 127}Xe, {sup 128}Cs, {sup 178}Ta and {sup 201}Tl frequently used in diagnostic procedures of nuclear medicine. The measurements of the excitation functions were made over a wide proton energy range from the reaction threshold up to 100 MeV using the stacked foil (or pellet) technique. Small energy steps were used to allow for accurate determination of the structure of excitation functions. For {sup 97}Ru, {sup 111}In and {sup 127}Xe formation with protons, new reaction channels and targets were used and data concerning this method are published for the first time. The data for {sup 52}Fe, {sup 77}Br, {sup 82}Rb, {sup 123}I, {sup 128}Cs and {sup 201}Tl obtained in the present work for the E{sub p}=70-100 MeV region are also published for the first time. The measured excitation functions for the formation of desired (and undesired) radionuclides (altogether 28 excitation functions) are compared with the theoretical ones calculated on the basis of a hybrid model of nuclear reactions in the form of the Overlaid Alice computer code. In order to determine the contribution of the competitive reaction channels to the purity of the produced, desired radionuclide, the excitation functions of the accompanying reactions were also calculated. The 122 calculated excitation functions for the possible contaminant are given. The comparison of experimental excitation functions with the results of model calculations showed satisfactory agreement; no parameter adjustment for individual reaction products was undertaken. Production yields for 28 radionuclides mentioned above were determined (author). 262 refs, 65 figs, 34 tabs.

  9. Excited-State Effective Masses in Lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    George Fleming, Saul Cohen, Huey-Wen Lin

    2009-10-01

    We apply black-box methods, i.e. where the performance of the method does not depend upon initial guesses, to extract excited-state energies from Euclidean-time hadron correlation functions. In particular, we extend the widely used effective-mass method to incorporate multiple correlation functions and produce effective mass estimates for multiple excited states. In general, these excited-state effective masses will be determined by finding the roots of some polynomial. We demonstrate the method using sample lattice data to determine excited-state energies of the nucleon and compare the results to other energy-level finding techniques.

  10. Modeling short-pulse laser excitation of dielectric materials

    DEFF Research Database (Denmark)

    Wædegaard, Kristian Juncher; Sandkamm, Ditte Både; Haahr-Lillevang, Lasse

    2014-01-01

    A theoretical description of ultrashort-pulse laser excitation of dielectric materials based on strong-field excitation in the Keldysh picture combined with a multiple-rateequation model for the electronic excitation including collisional processes is presented. The model includes light attenuation...... in a self-consistent manner and changing optical properties described in a Drude picture. The model can be used to calculate the electronic excitation as a function of time and depth, and from these quantities the time-dependent optical parameters as well as the ablation depth can be derived....... The simulations provide insight into the excitation and propagation dynamics of short-pulse excitation and show that at increasing fluence the excitation becomes localized near the material surface and gives rise to strongmodifications of the optical properties of the material....

  11. Work Function Adjustment by Using Dipole Engineering for TaN-Al2O3-Si3N4-HfSiOx-Silicon Nonvolatile Memory

    Directory of Open Access Journals (Sweden)

    Yu-Hsien Lin

    2015-08-01

    Full Text Available This paper presents a novel TaN-Al2O3-HfSiOx-SiO2-silicon (TAHOS nonvolatile memory (NVM design with dipole engineering at the HfSiOx/SiO2 interface. The threshold voltage shift achieved by using dipole engineering could enable work function adjustment for NVM devices. The dipole layer at the tunnel oxide–charge storage layer interface increases the programming speed and provides satisfactory retention. This NVM device has a high program/erase (P/E speed; a 2-V memory window can be achieved by applying 16 V for 10 μs. Regarding high-temperature retention characteristics, 62% of the initial memory window was maintained after 103 P/E-cycle stress in a 10-year simulation. This paper discusses the performance improvement enabled by using dipole layer engineering in the TAHOS NVM.

  12. The Functions of Onomatopoeia in Modern English and Arabic Poetry: A Study in Selected Poems by Lawrence and al-Sayyab

    Directory of Open Access Journals (Sweden)

    Haitham K. Al-Zubbaidi

    2014-12-01

    Full Text Available Onomatopoeia has always been a functional poetic device which enjoys a high sound significance in the poetry of many languages. In modern English and Arabic poetry alike, it proves to be vital and useful at different levels: musical, thematic and at the level of meaning. Still, the cultural difference looms large over the ways it is employed by the poets of each. The present paper investigates the employment of onomatopoeia in the poetry of D. H. Lawrence (1885-1930 and Badr Shakir al-Sayyab (1926-1964 who are chosen due to the importance they enjoy in modern English and Arabic poetry and the richness of their poems in onomatopoeias.  The conclusions reached at are in a sense related to cultural differences which govern the use of onomatopoeia for specific aims rather than for others.

  13. Structure and functional dynamics characterization of the ion channel of the human respiratory syncytial virus (hRSV) small hydrophobic protein (SH) transmembrane domain by combining molecular dynamics with excited normal modes.

    Science.gov (United States)

    Araujo, Gabriela C; Silva, Ricardo H T; Scott, Luis P B; Araujo, Alexandre S; Souza, Fatima P; de Oliveira, Ronaldo Junio

    2016-12-01

    The human respiratory syncytial virus (hRSV) is the major cause of lower respiratory tract infection in children and elderly people worldwide. Its genome encodes 11 proteins including SH protein, whose functions are not well known. Studies show that SH protein increases RSV virulence degree and permeability to small compounds, suggesting it is involved in the formation of ion channels. The knowledge of SH structure and function is fundamental for a better understanding of its infection mechanism. The aim of this study was to model, characterize, and analyze the structural behavior of SH protein in the phospholipids bilayer environment. Molecular modeling of SH pentameric structure was performed, followed by traditional molecular dynamics (MD) simulations of the protein immersed in the lipid bilayer. Molecular dynamics with excited normal modes (MDeNM) was applied in the resulting system in order to investigate long time scale pore dynamics. MD simulations support that SH protein is stable in its pentameric form. Simulations also showed the presence of water molecules within the bilayer by density distribution, thus confirming that SH protein is a viroporin. This water transport was also observed in MDeNM studies with histidine residues of five chains (His22 and His51), playing a key role in pore permeability. The combination of traditional MD and MDeNM was a very efficient protocol to investigate functional conformational changes of transmembrane proteins that act as molecular channels. This protocol can support future investigations of drug candidates by acting on SH protein to inhibit viral infection. Graphical Abstract The ion channel of the human respiratory syncytial virus (hRSV) small hydrophobic protein (SH) transmembrane domainᅟ.

  14. Direct excitation of butterfly states in Rydberg molecules

    Science.gov (United States)

    Lippe, Carsten; Niederpruem, Thomas; Thomas, Oliver; Eichert, Tanita; Ott, Herwig

    2016-05-01

    Since their first theoretical prediction Rydberg molecules have become an increasing field of research. These exotic states originate from the binding of a ground state atom in the electronic wave function of a highly-excited Rydberg atom mediated by a Fermi contact type interaction. A special class of long-range molecular states, the butterfly states, were first proposed by Greene et al.. These states arise from a shape resonance in the p-wave scattering channel of a ground state atom and a Rydberg electron and are characterized by an electron wavefunction whose density distribution resembles the shape of a butterfly. We report on the direct observation of deeply bound butterfly states of Rydberg molecules of 87 Rb. The butterfly states are studied by high resolution spectroscopy of UV-excited Rydberg molecules. We find states bound up to - 50 GHz from the 25 P1/2 , F = 1 state, corresponding to binding lengths of 50a0 to 500a0 and with permanent electric dipole moments of up to 500 Debye. This distinguishes the observed butterfly states from the previously observed long range Rydberg molecules in rubidium.

  15. Magnetic cluster excitations

    Science.gov (United States)

    Furrer, Albert; Waldmann, Oliver

    2013-01-01

    Magnetic clusters, i.e., assemblies of a finite number (between two or three and several hundred) of interacting spin centers which are magnetically decoupled from their environment, can be found in many materials ranging from inorganic compounds and magnetic molecules to artificial metal structures formed on surfaces and metalloproteins. Their magnetic excitation spectra are determined by the nature of the spin centers and of the magnetic interactions, and the particular arrangement of the mutual interaction paths between the spin centers. Small clusters of up to four magnetic ions are ideal model systems in which to examine the fundamental magnetic interactions, which are usually dominated by Heisenberg exchange, but often complemented by anisotropic and/or higher-order interactions. In large magnetic clusters, which may potentially deal with a dozen or more spin centers, there is the possibility of novel many-body quantum states and quantum phenomena. In this review the necessary theoretical concepts and experimental techniques to study the magnetic cluster excitations and the resulting characteristic magnetic properties are introduced, followed by examples of small clusters, demonstrating the enormous amount of detailed physical information that can be retrieved. The current understanding of the excitations and their physical interpretation in the molecular nanomagnets which represent large magnetic clusters is then presented, with a section devoted to the subclass of single-molecule magnets, distinguished by displaying quantum tunneling of the magnetization. Finally, there is a summary of some quantum many-body states which evolve in magnetic insulators characterized by built-in or field-induced magnetic clusters. The review concludes by addressing future perspectives in the field of magnetic cluster excitations.

  16. Synchronization of chaos in non-identical parametrically excited systems

    Energy Technology Data Exchange (ETDEWEB)

    Idowu, B.A. [Department of Physics, Lagos State University, Ojo (Nigeria)], E-mail: babaidowu@yahoo.com; Vincent, U.E. [Department of Physics, Olabisi Onabanjo University, P.M.B 2002, Ago-Iwoye (Nigeria)], E-mail: ue_vincent@yahoo.com; Njah, A.N. [Department of Physics, University of Agriculture, Abeokuta (Nigeria)

    2009-03-15

    In this paper, we investigate the synchronization of chaotic systems consisting of non-identical parametrically excited oscillators. The active control technique is employed to design control functions based on Lyapunov stability theory and Routh-Hurwitz criteria so as to achieve global chaos synchronization between a parametrically excited gyroscope and each of the parametrically excited pendulum and Duffing oscillator. Numerical simulations are implemented to verify the results.

  17. Motor axon excitability during Wallerian degeneration

    DEFF Research Database (Denmark)

    Moldovan, Mihai; Alvarez, Susana; Krarup, Christian

    2008-01-01

    , action potential propagation and structural integrity of the distal segment are maintained. The aim of this study was to investigate in vivo the changes in membrane function of motor axons during the 'latent' phase of Wallerian degeneration. Multiple indices of axonal excitability of the tibial nerve...

  18. Excited states of Ne isoelectronic ions: SAC-CI study

    Energy Technology Data Exchange (ETDEWEB)

    Das, A.K.; Ehara, M.; Nakatsuji, H. [Kyoto Univ. (Japan). Faculty of Engineering

    2001-02-01

    Excited states of the s, p, and d symmetries up to principal quantum number n = 4 are studied for the first eight members of Ne isoelectronic sequence (Ne to Cl{sup 7+}) by the SAC-CI (symmetry-adapted-cluster configuration-interaction) method. The valence STO basis sets of Clementi et al. and the optimized excited STO are used by the STO-6G expansion method. The calculated transition energies agree well with the experimental values wherever available. (orig.)

  19. Transition and Excited States of 1,1'-azo-bis-1,2,3-triazole

    Science.gov (United States)

    Goncharov, Vladimir; Goncharova, Olga; Varga, Kalman

    2011-03-01

    A novel photochromic molecule has been recently synthesized. The photo-isomerization of this nitrogen-rich small molecule is efficiently controlled by a xenon flash lamp suggesting a potential in photonic and molecular mechanics applications. We perform a synergistic quantum molecular dynamics (QMD), real-time time dependent density functional theory (TDDFT) and TDDFT- perturbation theory study to capture and elucidate the transition state, excitation energies and optical properties of the molecule. We also use it to test performance of recently developed real-time TDDFT method to calculate hyperpolarizabilities and compare results with the Sternheimer method. Yu-Chuan Li et al. J. Am. Chem. Soc., 2010, 132, 12172

  20. Statistical dynamo theory: Mode excitation.

    Science.gov (United States)

    Hoyng, P

    2009-04-01

    We compute statistical properties of the lowest-order multipole coefficients of the magnetic field generated by a dynamo of arbitrary shape. To this end we expand the field in a complete biorthogonal set of base functions, viz. B= summation operator_{k}a;{k}(t)b;{k}(r) . The properties of these biorthogonal function sets are treated in detail. We consider a linear problem and the statistical properties of the fluid flow are supposed to be given. The turbulent convection may have an arbitrary distribution of spatial scales. The time evolution of the expansion coefficients a;{k} is governed by a stochastic differential equation from which we infer their averages a;{k} , autocorrelation functions a;{k}(t)a;{k *}(t+tau) , and an equation for the cross correlations a;{k}a;{l *} . The eigenfunctions of the dynamo equation (with eigenvalues lambda_{k} ) turn out to be a preferred set in terms of which our results assume their simplest form. The magnetic field of the dynamo is shown to consist of transiently excited eigenmodes whose frequency and coherence time is given by Ilambda_{k} and -1/Rlambda_{k} , respectively. The relative rms excitation level of the eigenmodes, and hence the distribution of magnetic energy over spatial scales, is determined by linear theory. An expression is derived for |a;{k}|;{2}/|a;{0}|;{2} in case the fundamental mode b;{0} has a dominant amplitude, and we outline how this expression may be evaluated. It is estimated that |a;{k}|;{2}/|a;{0}|;{2} approximately 1/N , where N is the number of convective cells in the dynamo. We show that the old problem of a short correlation time (or first-order smoothing approximation) has been partially eliminated. Finally we prove that for a simple statistically steady dynamo with finite resistivity all eigenvalues obey Rlambda_{k}<0 .