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Sample records for hybrid pbe0 functional

  1. Evolution of the orbitals Dy-4f in the DyB2 compound using the LDA, PBE approximations, and the PBE0 hybrid functional

    Science.gov (United States)

    Rasero Causil, Diego; Ortega López, César; Espitia Rico, Miguel

    2018-04-01

    Computational calculations of total energy based on density functional theory were used to investigate the structural, electronic, and magnetic properties of the DyB2 compounds in the hexagonal structure. The calculations were carried out by means of the full-potential linearized augmented plane wave (FP-LAPW) method, employing the computational Wien2k package. The local density approximation (LDA) and the generalized gradient approximation (GGA) were used for the electron-electron interactions. Additionally, we used the functional hybrid PBE0 for a better description the electronic and magnetic properties, because the DyB2 compound is a strongly-correlated system. We found that the calculated lattice constant agrees well with the values reported theoretically and experimentally. The density of states (DOS) calculation shows that the compound exhibits a metallic behavior and has magnetic properties, with a total magnetic moment of 5.47 μ0/cell determined mainly by the 4f states of the rare earth elements. The functional PBE0 shows a strong localization of the Dy-4f orbitals.

  2. Hybrid functional pseudopotentials

    Science.gov (United States)

    Yang, Jing; Tan, Liang Z.; Rappe, Andrew M.

    2018-02-01

    The consistency between the exchange-correlation functional used in pseudopotential construction and in the actual density functional theory calculation is essential for the accurate prediction of fundamental properties of materials. However, routine hybrid density functional calculations at present still rely on generalized gradient approximation pseudopotentials due to the lack of hybrid functional pseudopotentials. Here, we present a scheme for generating hybrid functional pseudopotentials, and we analyze the importance of pseudopotential density functional consistency for hybrid functionals. For the PBE0 hybrid functional, we benchmark our pseudopotentials for structural parameters and fundamental electronic gaps of the Gaussian-2 (G2) molecular dataset and some simple solids. Our results show that using our PBE0 pseudopotentials in PBE0 calculations improves agreement with respect to all-electron calculations.

  3. Communication: Evaluating non-empirical double hybrid functionals for spin-state energetics in transition-metal complexes

    Science.gov (United States)

    Wilbraham, Liam; Adamo, Carlo; Ciofini, Ilaria

    2018-01-01

    The computationally assisted, accelerated design of inorganic functional materials often relies on the ability of a given electronic structure method to return the correct electronic ground state of the material in question. Outlining difficulties with current density functionals and wave function-based approaches, we highlight why double hybrid density functionals represent promising candidates for this purpose. In turn, we show that PBE0-DH (and PBE-QIDH) offers a significant improvement over its hybrid parent functional PBE0 [as well as B3LYP* and coupled cluster singles and doubles with perturbative triples (CCSD(T))] when computing spin-state splitting energies, using high-level diffusion Monte Carlo calculations as a reference. We refer to the opposing influence of Hartree-Fock (HF) exchange and MP2, which permits higher levels of HF exchange and a concomitant reduction in electronic density error, as the reason for the improved performance of double-hybrid functionals relative to hybrid functionals. Additionally, using 16 transition metal (Fe and Co) complexes, we show that low-spin states are stabilised by increasing contributions from MP2 within the double hybrid formulation. Furthermore, this stabilisation effect is more prominent for high field strength ligands than low field strength ligands.

  4. The shortcomings of semi-local and hybrid functionals: what we can learn from surface science studies

    International Nuclear Information System (INIS)

    Stroppa, A; Kresse, G

    2008-01-01

    A study of the adsorption of CO on late 4d and 5d transition metal (111) surfaces (Ru, Rh, Pd, Ag, Os, Ir and Pt) considering atop and hollow site adsorption is presented. The applied functionals include the gradient-corrected Perdew-Burke-Ernzerhof (PBE) and Becke-Lee-Yang-Parr (BLYP) functionals, and the corresponding hybrid Hartree-Fock density functionals HSE and B3LYP. We find that PBE-based hybrid functionals (specifically HSE) yield, with the exception of Pt, the correct site order on all considered metals, but they also considerably overestimate the adsorption energies compared to experiment. On the other hand, the semi-local BLYP functional and the corresponding hybrid functional B3LYP yield very satisfactory adsorption energies and the correct adsorption site for all surfaces. We are thus faced with a Procrustean problem: the B3LYP and BLYP functionals seem to be the overall best choice for describing adsorption on metal surfaces, but they simultaneously fail to account well for the properties of the metal, vastly overestimating the equilibrium volume and underestimating the atomization energies. Setting out from these observations, general conclusions are drawn on the relative merits and drawbacks of various semi-local and hybrid functionals. The discussion includes a revised version of the PBE functional specifically optimized for bulk properties and surface energies (PBEsol), a revised version of the PBE functional specifically optimized to predict accurate adsorption energies (rPBE), as well as the aforementioned BLYP functional. We conclude that no semi-local functional is capable of describing all aspects properly, and including non-local exchange also only improves some but worsens other properties

  5. Density Functional Theory applied to magnetic materials: Mn{sub 3}O{sub 4} at different hybrid functionals

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, R.A.P. [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Lazaro, S.R. de, E-mail: srlazaro@upeg.br [Department of Chemistry, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil); Pianaro, S.A. [Department of Materials Engineering, State University of Ponta Grossa, Av. General Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR (Brazil)

    2015-10-01

    Antiferromagnetic Mn{sub 3}O{sub 4} in spinel structure was investigated employing the Density Functional Theory at different hybrid functionals with default HF exchange percentage. Structural, electronic and magnetic properties were examined. Structural results were in agreement with experimental and Hartree–Fock results showing that the octahedral site was distorted by the Jahn–Teller effect, which changed the electron density distribution. Band-gap results for B3LYP and B3PW hybrid functionals were closer to the experimental when compared to PBE0. Mulliken Population Analysis revealed magnetic moments very close to ideal d{sup 4} and d{sup 5} electron configurations of Mn{sup 3+} and Mn{sup 2+}, respectively. Electron density maps are useful to determine that oxygen atoms mediate the electron transfer between octahedral and tetrahedral clusters. Magnetic properties were investigated from theoretical results for exchange coupling constants. Intratetrahedral and tetra-octahedral interactions were observed to be antiferromagnetic, whereas, octahedral sites presented antiferromagnetic interactions in the same layer and ferromagnetic in adjacent layers. Results showed that only default B3LYP was successful to describe magnetic properties of antiferromagnetic materials in agreement with experimental results. - Highlights: • We study structural, electronic and magnetic properties of antiferromagnetic Mn{sub 3}O{sub 4}. • B3LYP, B3PW and PBE0 hybrid functionals are compared. • B3LYP and B3PW hybrid functionals are better to band-gap calculations. • Only default B3LYP was successful to describe exchange interactions for Mn{sub 3}O{sub 4}.

  6. First-principles study of SnS electronic properties using LDA, PBE and HSE06 functionals

    Science.gov (United States)

    Ibragimova, R.; Ganchenkova, M.; Karazhanov, S.; Marstein, E. S.

    2018-03-01

    Recently, tin sulphide (SnS) has emerged as a promising alternative to conventional CIGS and CZTC for use in solar cells, possessing such properties as non-toxicity, low cost and production stability. SnS has a high theoretically predicted efficiency above 20%, but the experimentally achieved efficiency so far is as low as 4.36%. The reason for the low achieved efficiency is unclear. One of the powerful tools to get deeper insights about the nature of the problem is first-principles calculation approaches. That is why SnS has become an attractive subject for first-principles calculations recently. Previously calculated data, however, show a widespread of such fundamental value as the bandgap varying from 0.26 to 1.26 eV. In order to understand a reason for that, in this work, we concentrate on a systematic study of calculation parameters effects on the resulting electronic structure, with the particular attention paid to the influence of the exchange-correlation functional chosen for calculations. Several exchange-correlation functionals (LDA, PBE and HSE06) were considered. The systematic analysis has shown that the bandgap variation can result from a tensile/compressive hydrostatic pressure introduced by non-equilibrium lattice parameters used for the calculations. The study of the applicability of three functionals has shown that HSE06 gives the best match to both experimentally obtained bandgap and the XPS valence band spectra. LDA underestimates the bandgap but qualitatively reproduces experimentally measured valence DOS similar to that of HSE06 in contrast to PBE. PBE underestimates the bandgap and does not match to the measured XPS spectra.

  7. Computational Investigation of the Geometrical and Electronic Structures of VGen-/0 (n = 1-4) Clusters by Density Functional Theory and Multiconfigurational CASSCF/CASPT2 Method.

    Science.gov (United States)

    Tran, Van Tan; Nguyen, Minh Thao; Tran, Quoc Tri

    2017-10-12

    Density functional theory and the multiconfigurational CASSCF/CASPT2 method have been employed to study the low-lying states of VGe n -/0 (n = 1-4) clusters. For VGe -/0 and VGe 2 -/0 clusters, the relative energies and geometrical structures of the low-lying states are reported at the CASSCF/CASPT2 level. For the VGe 3 -/0 and VGe 4 -/0 clusters, the computational results show that due to the large contribution of the Hartree-Fock exact exchange, the hybrid B3LYP, B3PW91, and PBE0 functionals overestimate the energies of the high-spin states as compared to the pure GGA BP86 and PBE functionals and the CASPT2 method. On the basis of the pure GGA BP86 and PBE functionals and the CASSCF/CASPT2 results, the ground states of anionic and neutral clusters are defined, the relative energies of the excited states are computed, and the electron detachment energies of the anionic clusters are evaluated. The computational results are employed to give new assignments for all features in the photoelectron spectra of VGe 3 - and VGe 4 - clusters.

  8. Optimizing the Structure of Tetracyanoplatinate (II): A Comparison of Relativistic Density Functional Theory Methods

    DEFF Research Database (Denmark)

    Dohn, Asmus Ougaard; Møller, Klaus Braagaard; Sauer, Stephan P. A.

    2013-01-01

    is almost quantitatively reproduced in the ZORA and ECP calculations. In addition, the effect of the exchange-correlation functional and one-electron basis set was studied by employing the two generalized gradient approximation (GGA) functionals, BLYP and PBE, as well as their hybrid version B3LYP and PBE0...

  9. Structural, magnetic, electronic and optical properties of PuC and PuC{sub 0.75}: A hybrid density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rong [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); College of Materials Science and Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Tang, Bin [School of Business Administration, Chongqing City Management College, Chongqing 401331 (China); Gao, Tao, E-mail: gaotao@scu.edu.cn [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Ao, BingYun, E-mail: aobingyun@caep.cn [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China)

    2016-05-15

    We perform first principles calculations to investigate the structural, magnetic, electronic and optical properties of PuC and PuC{sub 0.75}. Furthermore, we examine the influence of carbon non-stoichiometry on plutonium monocarbide. For the treatment of strongly correlated electrons, the hybrid density functionals like PBE0, Fock-0.25 are used and we compare the results with the generalized gradient approximation (GGA), local density approximation (LDA), LDA + U and experimental ones. The optimized lattice constant a{sub 0} = 4.961 Å for PuC in the Fock-0.25 scheme is the most close to the experimental data. The ground states of PuC and PuC{sub 0.75} are found to be anti-ferromagnetic. Our results indicate that additional removal of a C atom make lattice contract and new DOS peak appear in the near-Fermi region. We also compute and compare the optical properties of PuC and PuC{sub 0.75}. The difference in optical properties between PuC and PuC{sub 0.75} should also be the influence of carbon vacancies.

  10. Exchange-correlation energies of atoms from efficient density functionals: influence of the electron density

    Science.gov (United States)

    Tao, Jianmin; Ye, Lin-Hui; Duan, Yuhua

    2017-12-01

    The primary goal of Kohn-Sham density functional theory is to evaluate the exchange-correlation contribution to electronic properties. However, the accuracy of a density functional can be affected by the electron density. Here we apply the nonempirical Tao-Mo (TM) semilocal functional to study the influence of the electron density on the exchange and correlation energies of atoms and ions, and compare the results with the commonly used nonempirical semilocal functionals local spin-density approximation (LSDA), Perdew-Burke-Ernzerhof (PBE), Tao-Perdew-Staroverov-Scuseria (TPSS), and hybrid functional PBE0. We find that the spin-restricted Hartree-Fock density yields the exchange and correlation energies in good agreement with the Optimized Effective Potential method, particularly for spherical atoms and ions. However, the errors of these semilocal and hybrid functionals become larger for self-consistent densities. We further find that the quality of the electron density have greater effect on the exchange-correlation energies of kinetic energy density-dependent meta-GGA functionals TPSS and TM than on those of the LSDA and GGA, and therefore, should have greater influence on the performance of meta-GGA functionals. Finally, we show that the influence of the density quality on PBE0 is slightly reduced, compared to that of PBE, due to the exact mixing.

  11. On the accuracy of density-functional theory exchange-correlation functionals for H bonds in small water clusters: Benchmarks approaching the complete basis set limit

    Science.gov (United States)

    Santra, Biswajit; Michaelides, Angelos; Scheffler, Matthias

    2007-11-01

    The ability of several density-functional theory (DFT) exchange-correlation functionals to describe hydrogen bonds in small water clusters (dimer to pentamer) in their global minimum energy structures is evaluated with reference to second order Møller-Plesset perturbation theory (MP2). Errors from basis set incompleteness have been minimized in both the MP2 reference data and the DFT calculations, thus enabling a consistent systematic evaluation of the true performance of the tested functionals. Among all the functionals considered, the hybrid X3LYP and PBE0 functionals offer the best performance and among the nonhybrid generalized gradient approximation functionals, mPWLYP and PBE1W perform best. The popular BLYP and B3LYP functionals consistently underbind and PBE and PW91 display rather variable performance with cluster size.

  12. Electronic properties of CdWO{sub 4}: Use of hybrid exchange and correlation functionals

    Energy Technology Data Exchange (ETDEWEB)

    Meena, B. S., E-mail: bsmphysics@gmail.com; Mund, H. S.; Ahuja, B. L. [Department of Physics, University College of Science, M. L. Sukhadia University, Udaipur-313001 (India); Heda, N. L. [Department of Pure and Applied Physics, University of Kota, Kota-324010 (India)

    2016-05-23

    Energy bands, density of states (DOS), Mulliken population (MP) and electron momentum densities (EMDs) of CdWO{sub 4} are presented using hybrid exchange and correlation functionals namely B3LYP, B3PW and PBE0. To validate the present hybrid potentials, theoretical EMDs have been compared with the experimental Compton profile. It is found that LCAO-B3LYP based Compton profile gives a better agreement with experiment than other theoretical profiles. The energy bands and DOS show a wide band gap semiconducting nature of CdWO{sub 4}. The theoretical band gap obtained using B3LYP scheme reconciles well with the available experimental data. In addition, we have also presented the anisotropies in EMDs along [100], [110] and [001] directions and the bonding effects using the MP data.

  13. Electronic structure of bulk AnO{sub 2} (An = U, Np, Pu) and water adsorption on the (111) and (110) surfaces of UO{sub 2} and PuO{sub 2} from hybrid density functional theory within the periodic electrostatic embedded cluster method

    Energy Technology Data Exchange (ETDEWEB)

    Wellington, Joseph P.W. [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Kerridge, Andrew [Department of Chemistry, Lancaster University, Bailrigg, Lancaster LA1 4YP (United Kingdom); Austin, Jonathan [National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington WA3 6AE (United Kingdom); Kaltsoyannis, Nikolas, E-mail: nikolas.kaltsoyannis@manchester.ac.uk [School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2016-12-15

    Generalised gradient approximation (PBE) and hybrid (PBE0) density functional theory (DFT) within the periodic electrostatic embedded cluster method have been used to study AnO{sub 2} bulk and surfaces (An = U, Np, Pu). The electronic structure has been investigated by examining the projected density of states (PDOS). While PBE incorrectly predicts these systems to be metallic, PBE0 finds them to be insulators, with the composition of the valence and conduction levels agreeing well with experiment. Molecular and dissociative water adsorption on the (111) and (110) surfaces of UO{sub 2} and PuO{sub 2} has been investigated, with that on the (110) surface being stronger than on the (111). Similar energies are found for molecular and dissociative adsorption on the (111) surfaces, while on the (110) there is a clear preference for dissociative adsorption. Adsorption energies and geometries on the (111) surface of UO{sub 2} are in good agreement with recent periodic DFT studies using the GGA+U approach, and our data for dissociative adsorption on the (110) surface of PuO{sub 2} match experiment rather well, especially when dispersion corrections are included. - Graphical abstract: The electronic structures of AnO{sub 2} (An = U, Np, Pu) are studied computationally with hybrid density functional theory, and the geometries and energetics of water adsorption on the low index surfaces are presented.

  14. Optical rotation calculated with time-dependent density functional theory: the OR45 benchmark.

    Science.gov (United States)

    Srebro, Monika; Govind, Niranjan; de Jong, Wibe A; Autschbach, Jochen

    2011-10-13

    Time-dependent density functional theory (TDDFT) computations are performed for 42 organic molecules and three transition metal complexes, with experimental molar optical rotations ranging from 2 to 2 × 10(4) deg cm(2) dmol(-1). The performances of the global hybrid functionals B3LYP, PBE0, and BHLYP, and of the range-separated functionals CAM-B3LYP and LC-PBE0 (the latter being fully long-range corrected), are investigated. The performance of different basis sets is studied. When compared to liquid-phase experimental data, the range-separated functionals do, on average, not perform better than B3LYP and PBE0. Median relative deviations between calculations and experiment range from 25 to 29%. A basis set recently proposed for optical rotation calculations (LPol-ds) on average does not give improved results compared to aug-cc-pVDZ in TDDFT calculations with B3LYP. Individual cases are discussed in some detail, among them norbornenone for which the LC-PBE0 functional produced an optical rotation that is close to available data from coupled-cluster calculations, but significantly smaller in magnitude than the liquid-phase experimental value. Range-separated functionals and BHLYP perform well for helicenes and helicene derivatives. Metal complexes pose a challenge to first-principles calculations of optical rotation.

  15. Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals

    Science.gov (United States)

    Pašti, Igor A.; Jovanović, Aleksandar; Dobrota, Ana S.; Mentus, Slavko V.; Johansson, Börje; Skorodumova, Natalia V.

    2018-04-01

    The understanding of atomic adsorption on graphene is of high importance for many advanced technologies. Here we present a complete database of the atomic adsorption energies for the elements of the Periodic Table up to the atomic number 86 (excluding lanthanides) on pristine graphene. The energies have been calculated using the projector augmented wave (PAW) method with PBE, long-range dispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local vdW-DF2 approach. The inclusion of dispersion interactions leads to an exothermic adsorption for all the investigated elements. Dispersion interactions are found to be of particular importance for the adsorption of low atomic weight earth alkaline metals, coinage and s-metals (11th and 12th groups), high atomic weight p-elements and noble gases. We discuss the observed adsorption trends along the groups and rows of the Periodic Table as well some computational aspects of modelling atomic adsorption on graphene.

  16. Effect of oxygen incorporation on the vibrational properties of Al0.2Ga0.3In0.5P:Be films

    International Nuclear Information System (INIS)

    Soubervielle-Montalvo, C.; Vital-Ochoa, O.; Anda, F. de; Vazquez-Cortes, D.; Rodriguez, A.G.; Melendez-Lira, M.; Mendez-Garcia, V.H.

    2011-01-01

    The vibrational properties of Al 0.2 Ga 0.3 In 0.5 P:Be films grown on (100) GaAs substrates by solid source molecular beam epitaxy varying the phosphorous cracking-zone temperature (PCT) were studied by Raman spectroscopy. The Raman-intensity ratio between the allowed longitudinal optical and the forbidden transverse optical (TO) phonons, and the full width at half maximum of their Lorentzian fits were used to characterize the crystalline quality of the films. The Raman spectra from the samples show changes in the shape and intensity of phonon resonances depending on the PCT variation, indicating that the disorder in the lattice increases with PCT. The increasing disorder is related to the inclusion of oxygen, which act as a non-intentional perturbing impurity in the lattice. In addition, a vibrational mode located at 598 cm -1 related to a forbidden InP-like TO phonon resonance was correlated with oxygen-induced disorder. Photoluminescence at room temperature shows that the high inclusion of oxygen also deteriorates the optical properties of the samples, by introducing non-radiative recombination centers.

  17. When Density Functional Approximations Meet Iron Oxides.

    Science.gov (United States)

    Meng, Yu; Liu, Xing-Wu; Huo, Chun-Fang; Guo, Wen-Ping; Cao, Dong-Bo; Peng, Qing; Dearden, Albert; Gonze, Xavier; Yang, Yong; Wang, Jianguo; Jiao, Haijun; Li, Yongwang; Wen, Xiao-Dong

    2016-10-11

    Three density functional approximations (DFAs), PBE, PBE+U, and Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe 2 O 3 , Fe 3 O 4 , and FeO. Comparing our calculated results with available experimental data, we found that HSE (a = 0.15) (containing 15% "screened" Hartree-Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (a = 0.25) seriously overestimates the band gaps and formation energies. For PBE+U, a suitable U value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same U value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (a = 0.15) functional and plotted the equilibrium phase diagrams of the iron oxide system under various conditions, which provide reliable theoretical insight into the phase transformations of iron oxides.

  18. Towards improved local hybrid functionals by calibration of exchange-energy densities

    International Nuclear Information System (INIS)

    Arbuznikov, Alexei V.; Kaupp, Martin

    2014-01-01

    A new approach for the calibration of (semi-)local and exact exchange-energy densities in the context of local hybrid functionals is reported. The calibration functions are derived from only the electron density and its spatial derivatives, avoiding spatial derivatives of the exact-exchange energy density or other computationally unfavorable contributions. The calibration functions fulfill the seven more important out of nine known exact constraints. It is shown that calibration improves substantially the definition of a non-dynamical correlation energy term for generalized gradient approximation (GGA)-based local hybrids. Moreover, gauge artifacts in the potential-energy curves of noble-gas dimers may be corrected by calibration. The developed calibration functions are then evaluated for a large range of energy-related properties (atomization energies, reaction barriers, ionization potentials, electron affinities, and total atomic energies) of three sets of local hybrids, using a simple one-parameter local-mixing. The functionals are based on (a) local spin-density approximation (LSDA) or (b) Perdew-Burke-Ernzerhof (PBE) exchange and correlation, and on (c) Becke-88 (B88) exchange and Lee-Yang-Parr (LYP) correlation. While the uncalibrated GGA-based functionals usually provide very poor thermochemical data, calibration allows a dramatic improvement, accompanied by only a small deterioration of reaction barriers. In particular, an optimized BLYP-based local-hybrid functional has been found that is a substantial improvement over the underlying global hybrids, as well as over previously reported LSDA-based local hybrids. It is expected that the present calibration approach will pave the way towards new generations of more accurate hyper-GGA functionals based on a local mixing of exchange-energy densities

  19. Prompt Burst Energetics (PBE) experiment analyses using the SIMMER-II computer code

    International Nuclear Information System (INIS)

    Tomkins, J.L.; Hitchcock, J.T.; Young, M.F.

    1979-01-01

    Two of the Prompt Burst Energetics (PBE) in-pile experiments conducted at Sandia Laboratories PBE-5S and PBE-SG2, have been investigated with SIMMER-II. These two tests utilize fresh uranium oxide and fresh uranium carbide pins, respectively, in stagnant sodium. The purpose of the analysis is to investigate the applicability of SIMMER-II to this type of experiment. Qualitative agreement with measured data is seen for PBE-5S. PBE-SG2 results agree somewhat less well but demonstrate SIMMER-II's potential for describing fuel-coolant-interactions with further model development

  20. Performance of Density Functional Theory Procedures for the Calculation of Proton-Exchange Barriers: Unusual Behavior of M06-Type Functionals.

    Science.gov (United States)

    Chan, Bun; Gilbert, Andrew T B; Gill, Peter M W; Radom, Leo

    2014-09-09

    We have examined the performance of a variety of density functional theory procedures for the calculation of complexation energies and proton-exchange barriers, with a focus on the Minnesota-class of functionals that are generally highly robust and generally show good accuracy. A curious observation is that M05-type and M06-type methods show an atypical decrease in calculated barriers with increasing proportion of Hartree-Fock exchange. To obtain a clearer picture of the performance of the underlying components of M05-type and M06-type functionals, we have investigated the combination of MPW-type and PBE-type exchange and B95-type and PBE-type correlation procedures. We find that, for the extensive E3 test set, the general performance of the various hybrid-DFT procedures improves in the following order: PBE1-B95 → PBE1-PBE → MPW1-PBE → PW6-B95. As M05-type and M06-type procedures are related to PBE1-B95, it would be of interest to formulate and examine the general performance of an alternative Minnesota DFT method related to PW6-B95.

  1. Electronic structure modeling of InAs/GaSb superlattices with hybrid density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Garwood, Tristan [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Modine, Normand A. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Krishna, S. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials

    2016-12-18

    The application of first-principles calculations holds promise for greatly improving our understanding of semiconductor superlattices. By developing a procedure to accurately predict band gaps using hybrid density functional theory, it lays the groundwork for future studies investigating more nuanced properties of these structures. Our approach allows a priori prediction of the properties of SLS structures using only the band gaps of the constituent materials. Furthermore, it should enable direct investigation of the effects of interface structure, e.g., intermixing or ordering at the interface, on SLS properties. In this paper, we present band gap data for various InAs/GaSb type-II superlattice structures calculated using the generalized Kohn-Sham formulation of density functional theory. A PBE0-type hybrid functional was used, and the portion of the exact exchange was tuned to fit the band gaps of the binary compounds InAs and GaSb with the best agreement to bulk experimental values obtained with 18% of the exact exchange. The heterostructures considered in this study are 6 monolayer (ML) InAs/6 ML GaSb, 8 ML InAs/8 ML GaSb and 10 ML InAs/10 ML GaSb with deviations from the experimental band gaps ranging from 3% to 11%.

  2. Extensive TD-DFT Benchmark: Singlet-Excited States of Organic Molecules.

    Science.gov (United States)

    Jacquemin, Denis; Wathelet, Valérie; Perpète, Eric A; Adamo, Carlo

    2009-09-08

    Extensive Time-Dependent Density Functional Theory (TD-DFT) calculations have been carried out in order to obtain a statistically meaningful analysis of the merits of a large number of functionals. To reach this goal, a very extended set of molecules (∼500 compounds, >700 excited states) covering a broad range of (bio)organic molecules and dyes have been investigated. Likewise, 29 functionals including LDA, GGA, meta-GGA, global hybrids, and long-range-corrected hybrids have been considered. Comparisons with both theoretical references and experimental measurements have been carried out. On average, the functionals providing the best match with reference data are, one the one hand, global hybrids containing between 22% and 25% of exact exchange (X3LYP, B98, PBE0, and mPW1PW91) and, on the other hand, a long-range-corrected hybrid with a less-rapidly increasing HF ratio, namely LC-ωPBE(20). Pure functionals tend to be less consistent, whereas functionals incorporating a larger fraction of exact exchange tend to underestimate significantly the transition energies. For most treated cases, the M05 and CAM-B3LYP schemes deliver fairly small deviations but do not outperform standard hybrids such as X3LYP or PBE0, at least within the vertical approximation. With the optimal functionals, one obtains mean absolute deviations smaller than 0.25 eV, though the errors significantly depend on the subset of molecules or states considered. As an illustration, PBE0 and LC-ωPBE(20) provide a mean absolute error of only 0.14 eV for the 228 states related to neutral organic dyes but are completely off target for cyanine-like derivatives. On the basis of comparisons with theoretical estimates, it also turned out that CC2 and TD-DFT errors are of the same order of magnitude, once the above-mentioned hybrids are selected.

  3. Effect of oxygen incorporation on the vibrational properties of Al{sub 0.2}Ga{sub 0.3}In{sub 0.5}P:Be films

    Energy Technology Data Exchange (ETDEWEB)

    Soubervielle-Montalvo, C., E-mail: csober22@gmail.com [Area de Computacion e Informatica, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi, Av. Dr. Manuel Nava 8, Zona Universitaria, C.P. 78290, San Luis Potosi, S.L.P (Mexico); Vital-Ochoa, O. [Area de Computacion e Informatica, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi, Av. Dr. Manuel Nava 8, Zona Universitaria, C.P. 78290, San Luis Potosi, S.L.P (Mexico); Anda, F. de [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico); Vazquez-Cortes, D.; Rodriguez, A.G. [Coordinacion para la Innovacion y Aplicacion de la Ciencia y Tecnologia, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico); Melendez-Lira, M. [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Av. Instituto Politecnico Nacional 2508, San Pedro Zacatenco, C.P. 07360, Mexico, D.F. (Mexico); Mendez-Garcia, V.H. [Coordinacion para la Innovacion y Aplicacion de la Ciencia y Tecnologia, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Secc., C.P. 78210, San Luis Potosi, S.L.P. (Mexico)

    2011-10-31

    The vibrational properties of Al{sub 0.2}Ga{sub 0.3}In{sub 0.5}P:Be films grown on (100) GaAs substrates by solid source molecular beam epitaxy varying the phosphorous cracking-zone temperature (PCT) were studied by Raman spectroscopy. The Raman-intensity ratio between the allowed longitudinal optical and the forbidden transverse optical (TO) phonons, and the full width at half maximum of their Lorentzian fits were used to characterize the crystalline quality of the films. The Raman spectra from the samples show changes in the shape and intensity of phonon resonances depending on the PCT variation, indicating that the disorder in the lattice increases with PCT. The increasing disorder is related to the inclusion of oxygen, which act as a non-intentional perturbing impurity in the lattice. In addition, a vibrational mode located at 598 cm{sup -1} related to a forbidden InP-like TO phonon resonance was correlated with oxygen-induced disorder. Photoluminescence at room temperature shows that the high inclusion of oxygen also deteriorates the optical properties of the samples, by introducing non-radiative recombination centers.

  4. Global hybrids from the semiclassical atom theory satisfying the local density linear response.

    Science.gov (United States)

    Fabiano, Eduardo; Constantin, Lucian A; Cortona, Pietro; Della Sala, Fabio

    2015-01-13

    We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 2011, 106, 186406] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetic and structural testing, including thermochemistry and geometry, transition metal complexes, noncovalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20% of Hartree-Fock exchange and named hAPBE, performs remarkably well for a broad palette of systems and properties, being generally better than popular hybrids (PBE0 and B3LYP). Semiempirical dispersion corrections are also provided.

  5. A DFT-D study of structural and energetic properties of TiO2 modifications

    International Nuclear Information System (INIS)

    Moellmann, Jonas; Ehrlich, Stephan; Tonner, Ralf; Grimme, Stefan

    2012-01-01

    The structures and relative energies of the three naturally occurring modifications of titanium dioxide (rutile, brookite and anatase) were investigated. For an accurate description, atom-pairwise dispersion-corrected density functional theory (DFT-D) was applied. The DFT-D3 scheme was extended non-empirically to improve the description of Ti atoms in bulk systems. New dispersion coefficients were derived from TDDFT calculations for electrostatically embedded TiO 2 clusters. The dispersion coefficient C 6 TiTi is reduced by a factor of 18 compared to the free atom. The three TiO 2 modifications were optimized in periodic plane-wave calculations with dispersion-corrected GGA (PBE, revPBE) and hybrid density functionals (PBE0, revPBE0). The calculated lattice parameters are in good agreement with experimental data, in particular the dispersion-corrected PBE0 and revPBE0 hybrid functionals. Although the observed relative stabilities could not be reproduced in all cases, dispersion corrections improve the results. For an accurate description of bulk metal oxides, London dispersion is a prominent force that should not be neglected when energies and structures are computed with DFT. Additionally, the influence of dispersion interactions on the relaxation of the TiO 2 (110) surface is investigated.

  6. CER, PBE, SCIRehab, NIDRR, and other important abbreviations.

    Science.gov (United States)

    Dijkers, Marcel P; Whiteneck, Gale G; Gassaway, Julie

    2013-04-01

    Comparative effectiveness research (CER) has been receiving much attention (and government funding) in recent years, stemming from dissatisfaction with much medical and health care research, which does not produce actionable evidence that can be used by clinicians, patients, and policymakers. Rehabilitation research has been characterized by similar weaknesses and by often inadequate research designs. The SCIRehab study of the outcomes of inpatient spinal cord injury rehabilitation is one of a small number of rehabilitation practice-based evidence (PBE) studies in recent years that allows for the comparison of interventions by all disciplines for relevant real-life outcomes. This introduction to a series of articles resulting from the SCIRehab project discusses the need for and the nature of CER, and places the SCIRehab study and other PBE studies in the light of CER. After a description of the highlights of the analyses in this supplement, we provide a preliminary evaluation of SCIRehab, counting the articles and presentations from the study, the resources that went into this vast project, and the lessons learned that may benefit future rehabilitation PBE investigators. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  7. A PBE hybrid functional study of blue-shifting and red-shifting hydrogen bonds in p hydrocarbons

    Directory of Open Access Journals (Sweden)

    Boaz Galdino de Oliveira

    2009-07-01

    Full Text Available This study examines a selected group of p hydrocarbon complexes, represented by C2H4•••HCF3, C2H2•••HCF3, C2H4•••HCF3 and C2H2•••HCF3, from a theoretical point of view. From BPBE/6-311++G(d,p calculations, the geometrical results of these complexes revealed an elongation and shortening of the H—C bond lengths of chloroform (HCCl3 and fluoroform (HCF3, respectively. In terms of the infrared spectrum, the analysis of stretch frequencies revealed that the variations in the H—C modes are essentially recognized as red and blue-shifting modes. For the purposes of understanding the two vibrational phenomena of the p hydrocarbon complexes studied here, PBE/6-311++G(d,p calculations were carried out and partitioning of atomic charges derived from the ChelpG algorithm were also used. A theoretical justification of red- and blue-shift effects was drawn up using charge-transfer analysis, which is manifested in the p bonds of acetylene and ethylene to chloroform (H—CCl3 and fluoroform (H—CF3, respectively. Finally, a further debate regarding the distinct polarizability power of chloroform and fluoroform is presented, concluding that, in comparison with fluoroform, chloroform possesses the requisite features for conventional proton donors and a red-shift is therefore observed in the C2H4•••HCCl3 and C2H2•••HCCl3 complexes.

  8. Charge asymmetry and track multiplicity associated with high transverse momentum direct γ and π0 produced in pBe collisions

    International Nuclear Information System (INIS)

    Gamarnik, K.

    1986-01-01

    Away and Trigger Hemisphere charge asymmetry and Away and Trigger Regions track multiplicity in direct γ and π 0 events produced in pBe collisions have been studied. No significant difference in charge asymmetry was found between direct γ and π 0 events. In both direct γ and π 0 , the charge asymmetries showed a trend towards higher values with increasing trigger particle P/sub t/ for the Away Hemisphere, and towards lower values for the Trigger Hemisphere. No significant difference was observed in the direct γ and π 0 events particle multiplicity, except for the Away Region tracks with P/sub t/ above 0.5 GeV/c. In the latter case, π 0 events showed higher track multiplicity for trigger P/sub t/ above 4.5 GeV/c. In general, the Away Region had higher track multiplicity than the Trigger Region

  9. Evaluation of exchange-correlation functionals for time-dependent density functional theory calculations on metal complexes.

    Science.gov (United States)

    Holland, Jason P; Green, Jennifer C

    2010-04-15

    The electronic absorption spectra of a range of copper and zinc complexes have been simulated by using time-dependent density functional theory (TD-DFT) calculations implemented in Gaussian03. In total, 41 exchange-correlation (XC) functionals including first-, second-, and third-generation (meta-generalized gradient approximation) DFT methods were compared in their ability to predict the experimental electronic absorption spectra. Both pure and hybrid DFT methods were tested and differences between restricted and unrestricted calculations were also investigated by comparison of analogous neutral zinc(II) and copper(II) complexes. TD-DFT calculated spectra were optimized with respect to the experimental electronic absorption spectra by use of a Matlab script. Direct comparison of the performance of each XC functional was achieved both qualitatively and quantitatively by comparison of optimized half-band widths, root-mean-squared errors (RMSE), energy scaling factors (epsilon(SF)), and overall quality-of-fit (Q(F)) parameters. Hybrid DFT methods were found to outperform all pure DFT functionals with B1LYP, B97-2, B97-1, X3LYP, and B98 functionals providing the highest quantitative and qualitative accuracy in both restricted and unrestricted systems. Of the functionals tested, B1LYP gave the most accurate results with both average RMSE and overall Q(F) 0.990) for the copper complexes. The XC functional performance in spin-restricted TD-DFT calculations on the zinc complexes was found to be slightly worse. PBE1PBE, mPW1PW91 and B1LYP gave the most accurate results with typical RMSE and Q(F) values between 5.3 and 7.3%, and epsilon(SF) around 0.930. These studies illustrate the power of modern TD-DFT calculations for exploring excited state transitions of metal complexes. 2009 Wiley Periodicals, Inc.

  10. Orbital-dependent exchange-correlation functionals in density-functional theory realized by the FLAPW method

    Energy Technology Data Exchange (ETDEWEB)

    Betzinger, Markus

    2011-12-14

    In this thesis, we extended the applicability of the full-potential linearized augmented-plane-wave (FLAPW) method, one of the most precise, versatile and generally applicable electronic structure methods for solids working within the framework of density-functional theory (DFT), to orbital-dependent functionals for the exchange-correlation (xc) energy. Two different schemes that deal with orbital-dependent functionals, the Kohn-Sham (KS) and the generalized Kohn-Sham (gKS) formalism, have been realized. Hybrid functionals, combining some amount of the orbital-dependent exact exchange energy with local or semi-local functionals of the density, are implemented within the gKS scheme. We work in particular with the PBE0 hybrid of Perdew, Burke, and Ernzerhof. Our implementation relies on a representation of the non-local exact exchange potential - its calculation constitutes the most time consuming step in a practical calculation - by an auxiliary mixed product basis (MPB). In this way, the matrix elements of the Hamiltonian corresponding to the non-local potential become a Brillouin-zone (BZ) sum over vector-matrix-vector products. Several techniques are developed and explored to further accelerate our numerical scheme. We show PBE0 results for a variety of semiconductors and insulators. In comparison with experiment, the PBE0 functional leads to improved band gaps and an improved description of localized states. Even for the ferromagnetic semiconductor EuO with localized 4f electrons, the electronic and magnetic properties are correctly described by the PBE0 functional. Subsequently, we discuss the construction of the local, multiplicative exact exchange (EXX) potential from the non-local, orbital-dependent exact exchange energy. For this purpose we employ the optimized effective potential (OEP) method. Central ingredients of the OEP equation are the KS wave-function response and the single-particle density response function. We show that a balance between the LAPW

  11. Orbital-dependent exchange-correlation functionals in density-functional theory realized by the FLAPW method

    International Nuclear Information System (INIS)

    Betzinger, Markus

    2011-01-01

    In this thesis, we extended the applicability of the full-potential linearized augmented-plane-wave (FLAPW) method, one of the most precise, versatile and generally applicable electronic structure methods for solids working within the framework of density-functional theory (DFT), to orbital-dependent functionals for the exchange-correlation (xc) energy. Two different schemes that deal with orbital-dependent functionals, the Kohn-Sham (KS) and the generalized Kohn-Sham (gKS) formalism, have been realized. Hybrid functionals, combining some amount of the orbital-dependent exact exchange energy with local or semi-local functionals of the density, are implemented within the gKS scheme. We work in particular with the PBE0 hybrid of Perdew, Burke, and Ernzerhof. Our implementation relies on a representation of the non-local exact exchange potential - its calculation constitutes the most time consuming step in a practical calculation - by an auxiliary mixed product basis (MPB). In this way, the matrix elements of the Hamiltonian corresponding to the non-local potential become a Brillouin-zone (BZ) sum over vector-matrix-vector products. Several techniques are developed and explored to further accelerate our numerical scheme. We show PBE0 results for a variety of semiconductors and insulators. In comparison with experiment, the PBE0 functional leads to improved band gaps and an improved description of localized states. Even for the ferromagnetic semiconductor EuO with localized 4f electrons, the electronic and magnetic properties are correctly described by the PBE0 functional. Subsequently, we discuss the construction of the local, multiplicative exact exchange (EXX) potential from the non-local, orbital-dependent exact exchange energy. For this purpose we employ the optimized effective potential (OEP) method. Central ingredients of the OEP equation are the KS wave-function response and the single-particle density response function. We show that a balance between the LAPW

  12. The accuracy of geometries for iron porphyrin complexes from density functional theory

    DEFF Research Database (Denmark)

    Rydberg, Patrik Åke Anders; Olsen, Lars

    2009-01-01

    functionals is evaluated with regard to how they reproduce experimental structures. Seven different functionals (BP86, PBE, PBE0, TPSS, TPSSH, B3LYP, and B97-D) are used to study eight different iron porphyrin complexes. The results show that the TPSSH, PBE0, and TPSS functionals give the best results...... (absolute bond distance deviations of 0.015-0.016 A), but the geometries are well-reproduced by all functionals except B3LYP. We also test four different basis sets of double-zeta quality, and we find that a combination of double-zeta basis set of Schafer et al. on the iron atom and the 6-31G* basis set...

  13. Effect of Dietary Countermeasures and Impact of Gravity on Renal Calculi Size Distributions Predicted by PBE-System and PBE-CFD Models

    Science.gov (United States)

    Kassemi, M.; Thompson, D.; Goodenow, D.; Gokoglu, S.; Myers, J.

    2016-01-01

    Renal stone disease is not only a concern on earth but can conceivably pose a serious risk to the astronauts health and safety in Space. In this work, two different deterministic models based on a Population Balance Equation (PBE) analysis of renal stone formation are developed to assess the risks of critical renal stone incidence for astronauts during space travel. In the first model, the nephron is treated as a continuous mixed suspension mixed product removal crystallizer and the PBE for the nucleating, growing and agglomerating renal calculi is coupled to speciation calculations performed by JESS. Predictions of stone size distributions in the kidney using this model indicate that the astronaut in microgravity is at noticeably greater but still subcritical risk and recommend administration of citrate and augmented hydration as effective means of minimizing and containing this risk. In the second model, the PBE analysis is coupled to a Computational Fluid Dynamics (CFD) model for flow of urine and transport of Calcium and Oxalate in the nephron to predict the impact of gravity on the stone size distributions. Results presented for realistic 3D tubule and collecting duct geometries, clearly indicate that agglomeration is the primary mode of size enhancement in both 1g and microgravity. 3D numerical simulations seem to further indicate that there will be an increased number of smaller stones developed in microgravity that will likely pass through the nephron in the absence of wall adhesion. However, upon reentry to a 1g (Earth) or 38g (Mars) partial gravitational fields, the renal calculi can lag behind the urinary flow in tubules that are adversely oriented with respect to the gravitational field and grow agglomerate to large sizes that are sedimented near the wall with increased propensity for wall adhesion, plaque formation, and risk to the astronauts.

  14. Which Density Functional Should Be Used to Describe Protonated Water Clusters?

    Science.gov (United States)

    Shi, Ruili; Huang, Xiaoming; Su, Yan; Lu, Hai-Gang; Li, Si-Dian; Tang, Lingli; Zhao, Jijun

    2017-04-27

    Protonated water cluster is one of the most important hydrogen-bond network systems. Finding an appropriate DFT method to study the properties of protonated water clusters can substantially improve the economy in computational resources without sacrificing the accuracy compared to high-level methods. Using high-level MP2 and CCSD(T) methods as well as experimental results as benchmark, we systematically examined the effect of seven exchange-correlation GGA functionals (with BLYP, B3LYP, X3LYP, PBE0, PBE1W, M05-2X, and B97-D parametrizations) in describing the geometric parameters, interaction energies, dipole moments, and vibrational properties of protonated water clusters H + (H 2 O) 2-9,12 . The overall performance of all these functionals is acceptable, and each of them has its advantage in certain aspects. X3LYP is the best to describe the interaction energies, and PBE0 and M05-2X are also recommended to investigate interaction energies. PBE0 gives the best anharmonic frequencies, followed by PBE1W, B97-D and BLYP methods. PBE1W, B3LYP, B97-D, and X3LYP can yield better geometries. The capability of B97-D to distinguish the relative energies between isomers is the best among all the seven methods, followed by M05-2X and PBE0.

  15. The study of structural characteristic of yttrium(3+) aquaion by density functional methods

    International Nuclear Information System (INIS)

    Buz'ko, V.Yu.; Sukhno, I.V.; Polushin, A.A.; Panyushkin, V.T.

    2006-01-01

    Structural characteristics of the yttrium aquaion Y(H 2 O) 8 3+ are calculated by DFT technique using density functionals SVWN5, B3LYP, B3P86, O3LYP, B3PW91, B1LYP, B971, MPW1PW9, PBE1PBE, BHandH and BNandHLYP. All calculations are carried out by means of GAUSSIAN-03 code. Structural characteristics of the Y(H 2 O) 8 3+ aquaion obtained by the use of the density functional method agree satisfactorily with the experiment. Hybrid nonlocal GGA-functionals foretell worse the structural characteristics of the Y(H 2 O) 8 3+ aquaion as compared with the reasonable simple combined functional BHandH and the simplest functional SVWN5 of the LSDA theory [ru

  16. Difficulties in applying pure Kohn-Sham density functional theory electronic structure methods to protein molecules

    Science.gov (United States)

    Rudberg, Elias

    2012-02-01

    Self-consistency-based Kohn-Sham density functional theory (KS-DFT) electronic structure calculations with Gaussian basis sets are reported for a set of 17 protein-like molecules with geometries obtained from the Protein Data Bank. It is found that in many cases such calculations do not converge due to vanishing HOMO-LUMO gaps. A sequence of polyproline I helix molecules is also studied and it is found that self-consistency calculations using pure functionals fail to converge for helices longer than six proline units. Since the computed gap is strongly correlated to the fraction of Hartree-Fock exchange, test calculations using both pure and hybrid density functionals are reported. The tested methods include the pure functionals BLYP, PBE and LDA, as well as Hartree-Fock and the hybrid functionals BHandHLYP, B3LYP and PBE0. The effect of including solvent molecules in the calculations is studied, and it is found that the inclusion of explicit solvent molecules around the protein fragment in many cases gives a larger gap, but that convergence problems due to vanishing gaps still occur in calculations with pure functionals. In order to achieve converged results, some modeling of the charge distribution of solvent water molecules outside the electronic structure calculation is needed. Representing solvent water molecules by a simple point charge distribution is found to give non-vanishing HOMO-LUMO gaps for the tested protein-like systems also for pure functionals.

  17. Difficulties in applying pure Kohn-Sham density functional theory electronic structure methods to protein molecules

    International Nuclear Information System (INIS)

    Rudberg, Elias

    2012-01-01

    Self-consistency-based Kohn-Sham density functional theory (KS-DFT) electronic structure calculations with Gaussian basis sets are reported for a set of 17 protein-like molecules with geometries obtained from the Protein Data Bank. It is found that in many cases such calculations do not converge due to vanishing HOMO-LUMO gaps. A sequence of polyproline I helix molecules is also studied and it is found that self-consistency calculations using pure functionals fail to converge for helices longer than six proline units. Since the computed gap is strongly correlated to the fraction of Hartree-Fock exchange, test calculations using both pure and hybrid density functionals are reported. The tested methods include the pure functionals BLYP, PBE and LDA, as well as Hartree-Fock and the hybrid functionals BHandHLYP, B3LYP and PBE0. The effect of including solvent molecules in the calculations is studied, and it is found that the inclusion of explicit solvent molecules around the protein fragment in many cases gives a larger gap, but that convergence problems due to vanishing gaps still occur in calculations with pure functionals. In order to achieve converged results, some modeling of the charge distribution of solvent water molecules outside the electronic structure calculation is needed. Representing solvent water molecules by a simple point charge distribution is found to give non-vanishing HOMO-LUMO gaps for the tested protein-like systems also for pure functionals. (fast track communication)

  18. An LES-PBE-PDF approach for modeling particle formation in turbulent reacting flows

    Science.gov (United States)

    Sewerin, Fabian; Rigopoulos, Stelios

    2017-10-01

    Many chemical and environmental processes involve the formation of a polydispersed particulate phase in a turbulent carrier flow. Frequently, the immersed particles are characterized by an intrinsic property such as the particle size, and the distribution of this property across a sample population is taken as an indicator for the quality of the particulate product or its environmental impact. In the present article, we propose a comprehensive model and an efficient numerical solution scheme for predicting the evolution of the property distribution associated with a polydispersed particulate phase forming in a turbulent reacting flow. Here, the particulate phase is described in terms of the particle number density whose evolution in both physical and particle property space is governed by the population balance equation (PBE). Based on the concept of large eddy simulation (LES), we augment the existing LES-transported probability density function (PDF) approach for fluid phase scalars by the particle number density and obtain a modeled evolution equation for the filtered PDF associated with the instantaneous fluid composition and particle property distribution. This LES-PBE-PDF approach allows us to predict the LES-filtered fluid composition and particle property distribution at each spatial location and point in time without any restriction on the chemical or particle formation kinetics. In view of a numerical solution, we apply the method of Eulerian stochastic fields, invoking an explicit adaptive grid technique in order to discretize the stochastic field equation for the number density in particle property space. In this way, sharp moving features of the particle property distribution can be accurately resolved at a significantly reduced computational cost. As a test case, we consider the condensation of an aerosol in a developed turbulent mixing layer. Our investigation not only demonstrates the predictive capabilities of the LES-PBE-PDF model but also

  19. Performance of Several Density Functional Theory Methods on Describing Hydrogen-Bond Interactions.

    Science.gov (United States)

    Rao, Li; Ke, Hongwei; Fu, Gang; Xu, Xin; Yan, Yijing

    2009-01-13

    We have investigated eleven density functionals, including LDA, PBE, mPWPW91, TPSS, B3LYP, X3LYP, PBE0, O3LYP, B97-1, MPW1K, and TPSSh, for their performances on describing hydrogen bond (HB) interactions. The emphasis has been laid not only on their abilities to calculate the intermolecular hydrogen bonding energies but also on their performances in predicting the relative energies of intermolecular H-bonded complexes and the conformer stabilities due to intramolecular hydrogen bondings. As compared to the best theoretical values, we found that although PBE and PBE0 gave the best estimation of HB strengths, they might fail to predict the correct order of relative HB energies, which might lead to a wrong prediction of the global minimum for different conformers. TPSS and TPSSh did not always improve over PBE and PBE0. B3LYP was found to underestimate the intermolecular HB strengths but was among the best performers in calculating the relative HB energies. We showed here that X3LYP and B97-1 were able to give good values for both absolute HB strengths and relative HB energies, making these functionals good candidates for HB description.

  20. Ab initio calculation of pentacene-PbSe hybrid interface for photovoltaic applications.

    Science.gov (United States)

    Roy, P; Nguyen, Thao P

    2016-07-21

    We perform density functional theory (DFT) quantum chemical calculations for the pentacene-PbSe hybrid interface at both molecular and crystal levels. At the interface, the parallel orientation of pentacene on the PbSe surface is found to be the most favorable, analogous to a pentacene-gold interface. The molecule-surface distance and the value of charge transfer from one pentacene molecule to the PbSe surface are estimated at around 4.15 Å and 0.12 e(-) respectively. We found that, standard-LDA/GGA-PBE/hybrid/meta-GGA xc-functionals incorrectly determine the band gaps of both pentacene and PbSe and leads to a failed prediction of the energy alignment in this system. So, we use a relativistic G0W0 functional and accurately model the electronic properties of pentacene and PbSe in both bulk material and near the interface. An energy shift of 0.23 eV, due to the difference in work function at the interface was supplemented after a detailed analysis of the electrostatic potential. The highest occupied molecular orbital level of pentacene is 0.01 eV above PbSe while the lowest unoccupied molecular orbital of pentacene lies 1.70 eV above PbSe, allowing both electrons and holes to transfer along the donor-acceptor junction. Our results provide additional insights into the electronic structure properties of the pentacene-PbSe heterojunction and establish it as a promising and efficient candidate for photovoltaic applications.

  1. Electronic, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) by first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Munir, Junaid; Mat Isa, Ahmad Radzi [Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Yousaf, Masood [IBS Center for Multidimensional Carbon Materials, Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of); Aliabad, H.A. Rahnamaye [Department of Physics, Hakim Sabzevari University (Iran, Islamic Republic of); Ain, Qurat-ul [Key Laboratory for Laser Plasamas (MOE) & Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Saeed, M.A., E-mail: saeed@utm.my [Physics Department, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia)

    2016-10-15

    This article reports the electronic, structure, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) studied by employing density functional theory with local density approximation (LDA), generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof-96 (PBE) and modified Becke–Johnson (mBJ) exchange-correlation potential and energy. The band structure and density of states of these compounds are also presented. The total density of states (DOS) for up and down spin states clearly split, which means that the exchange interaction causes the ordered spin arrangement. PBE-mBJ calculation reveals a wider band gap in spin down state, which shows a half-metallic electronic character at the equilibrium state. The spin-polarized calculations indicate metallic nature in orthorhombic crystalline phase. It is also noted that the optical conductivity for PBE-mBJ is larger than that of LDA and PBE-GGA. Furthermore, the results show a half-metallic ferromagnetic ground state for Ni(pyz)V{sub 4}O{sub 10} in PBE-mBJ potential. The present results suggest Ni(pyz)V{sub 4}O{sub 10} compound as a potential candidate for the future optoelectronic and spintronic applications. - Highlights: • First study of the electronic, structure, magnetic and optical properties of reduced hybrid layered complex Ni(pyz)V{sub 4}O{sub 10} (pyz=C{sub 4}H{sub 4}N{sub 2}) by first principles. • PBE-mBJ calculation reveals a wider band gap in spin down state indicating its half-metallic electronic character. • The large spin magnetic moment on Ni and V cations indicates the ferromagnetic interaction which makes this compound suitable candidate for spintronics applications. • An optical band gap reveals that this compound is also useful for the application in optoelectronics.

  2. Hydrogen and dihydrogen bonding of transition metal hydrides

    Science.gov (United States)

    Jacobsen, Heiko

    2008-04-01

    Intermolecular interactions between a prototypical transition metal hydride WH(CO) 2NO(PH 3) 2 and a small proton donor H 2O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H⋯H bond of transition metal hydrides contains both covalent and electrostatic contributions.

  3. Hydrogen and dihydrogen bonding of transition metal hydrides

    International Nuclear Information System (INIS)

    Jacobsen, Heiko

    2008-01-01

    Intermolecular interactions between a prototypical transition metal hydride WH(CO) 2 NO(PH 3 ) 2 and a small proton donor H 2 O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H...H bond of transition metal hydrides contains both covalent and electrostatic contributions

  4. Benchmarking semiempirical and DFT methods for the interaction of thiophene and diethyl sulfide molecules with a Ti(OH)4(H2O) cluster.

    Science.gov (United States)

    Vorontsov, Alexander V; Smirniotis, Panagiotis G

    2017-08-01

    Semiempirical methods pm6 and pm7 as well as density functional theory functionals exchange LSDA, exchange-correlation PW91 and PBE, hybrid B3LYP1 and PBE0 were compared for energy and geometry of thiophene, diethyl sulfide (DES) molecules and their binding to a frozen Ti(OH) 4 (H 2 O) complex having one coordinatively unsaturated Ti 5C site representing small fragment of TiO 2 anatase (001) surface. PBE0/6-31G(d) with DFT-D3 dispersion correction was the best method for description of thiophene and DES molecules geometries as comparison with experimental data demonstrated. Semiempirical methods pm6 and pm7 resulted in only three of four possible binding configurations of thiophene with the Ti(OH) 4 (H 2 O) complex while pm7 described correctly the enthalpy and all configurations of DES binding with the Ti(OH) 4 (H 2 O) complex. SBKJC pseudopotential and LSDA with and without dispersion correction produced flawed results for many configurations. PBE0 and PBE with and without dispersion correction and PW91 with 6-31G(d) basis set systematically produced dependable results for thiophene and DES binding to the Ti(OH) 4 (H 2 O) complex. PBE0-D3/6-31G(d), B3LYP1-D3/6-31G(d), and PBE-D3/6-31G(d) gave best match of binding energy for thiophene while PBE0/6-31G(d) gave best match of DES binding energy as comparison with CCSD(T) energy demonstrated. On the basis of the superior results obtained with PBE0/6-31G(d), it is the recommended method for modeling of adsorption over TiO 2 surfaces. Such a conclusion is in agreement with recent literature.

  5. Assessing exchange-correlation functionals for elasticity and thermodynamics of α -ZrW2O8 : A density functional perturbation theory study

    Science.gov (United States)

    Weck, Philippe F.; Kim, Eunja; Greathouse, Jeffery A.; Gordon, Margaret E.; Bryan, Charles R.

    2018-04-01

    Elastic and thermodynamic properties of negative thermal expansion (NTE) α -ZrW2O8 have been calculated using PBEsol and PBE exchange-correlation functionals within the framework of density functional perturbation theory (DFPT). Measured elastic constants are reproduced within ∼ 2 % with PBEsol and ∼ 6 % with PBE. The thermal evolution of the Grüneisen parameter computed within the quasi-harmonic approximation exhibits negative values below the Debye temperature, consistent with observation. The standard molar heat capacity is predicted to be CP0 = 192.2 and 193.8 J mol-1K-1 with PBEsol and PBE, respectively. These results suggest superior accuracy of DFPT/PBEsol for studying the lattice dynamics, elasticity and thermodynamics of NTE materials.

  6. The study of p-Be collisions at 40 GeV/c z experiment NA57 at SPS accelerator at CERN

    International Nuclear Information System (INIS)

    Bombara, M.

    2005-01-01

    In this work the p-Be collisions at 40 GeV/c in NA57 experiment at CERN SPS were analysed. These collisions are expected to constitute a reference sample for a study of the strangeness production enhancement in Pb-Pb collisions. We concentrated on the analysis of strange particles Κ 0 , Λ and Λ'bar'. The particle signals were extracted by reconstructing their weak decays into nal states containing only charged particles: K 0 S → π + π - , Λ → pπ - and Λ'-' → p'-'π + using geometric and kinematic constraints. The data were corrected for geometrical acceptance and detector and reconstruction efficiencies on an event-by-event basis. For each particle species we defined the acceptance window using a Monte Carlo simulation of the apparatus. The double-differential (y,m T ) distribution for each particle species has been parametrized assuming the rapidity distribution to be at and the transverse momenta distribution to be exponential within our acceptance region. We extrapolated the yield measured in the selected acceptance window to a common phase space window covering full p T and one unit of rapidity centred at mid-rapidity. By comparison of yields in p-Be collisions and yields in Pb-Pb collisions we obtained the enhancements of strange production. The investigation of rapidity spectra shows non at behaviour for K 0 . A significant enhancement of strangeness production in Pb-Pb collisions with respect to p-Be collisions is observed in the 40 GeV/c data. (author)

  7. Performance of exchange-correlation functionals in density functional theory calculations for liquid metal: A benchmark test for sodium

    Science.gov (United States)

    Han, Jeong-Hwan; Oda, Takuji

    2018-04-01

    The performance of exchange-correlation functionals in density-functional theory (DFT) calculations for liquid metal has not been sufficiently examined. In the present study, benchmark tests of Perdew-Burke-Ernzerhof (PBE), Armiento-Mattsson 2005 (AM05), PBE re-parameterized for solids, and local density approximation (LDA) functionals are conducted for liquid sodium. The pair correlation function, equilibrium atomic volume, bulk modulus, and relative enthalpy are evaluated at 600 K and 1000 K. Compared with the available experimental data, the errors range from -11.2% to 0.0% for the atomic volume, from -5.2% to 22.0% for the bulk modulus, and from -3.5% to 2.5% for the relative enthalpy depending on the DFT functional. The generalized gradient approximation functionals are superior to the LDA functional, and the PBE and AM05 functionals exhibit the best performance. In addition, we assess whether the error tendency in liquid simulations is comparable to that in solid simulations, which would suggest that the atomic volume and relative enthalpy performances are comparable between solid and liquid states but that the bulk modulus performance is not. These benchmark test results indicate that the results of liquid simulations are significantly dependent on the exchange-correlation functional and that the DFT functional performance in solid simulations can be used to roughly estimate the performance in liquid simulations.

  8. Ground-State Gas-Phase Structures of Inorganic Molecules Predicted by Density Functional Theory Methods

    KAUST Repository

    Minenkov, Yury; Cavallo, Luigi

    2017-01-01

    -GGA approximations with B3PW91, APF, TPSSh, mPW1PW91, PBE0, mPW1PBE, B972, and B98 functionals, resulting in lowest errors. We recommend using these methods to predict accurate three-dimensional structures of inorganic molecules when intramolecular dispersion

  9. Hydrogen and dihydrogen bonding of transition metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, Heiko [KemKom, Libellenweg 2, 25917 Leck, Nordfriesland (Germany)], E-mail: jacobsen@kemkom.com

    2008-04-03

    Intermolecular interactions between a prototypical transition metal hydride WH(CO){sub 2}NO(PH{sub 3}){sub 2} and a small proton donor H{sub 2}O have been studied using DFT methodology. The hydride, nitrosyl and carbonyl ligand have been considered as site of protonation. Further, DFT-D calculations in which empirical corrections for the dispersion energy are included, have been carried out. A variety of pure and hybrid density functionals (BP86, PW91, PBE, BLYP, OLYP, B3LYP, B1PW91, PBE0, X3LYP) have been considered, and our calculations indicate the PBE functional and its hybrid variation are well suited for the calculation of transition metal hydride hydrogen and dihydrogen bonding. Dispersive interactions make up for a sizeable portion of the intermolecular interaction, and amount to 20-30% of the bond energy and to 30-40% of the bond enthalpy. An energy decomposition analysis reveals that the H...H bond of transition metal hydrides contains both covalent and electrostatic contributions.

  10. Bands dispersion and charge transfer in β-BeH2

    Science.gov (United States)

    Trivedi, D. K.; Galav, K. L.; Joshi, K. B.

    2018-04-01

    Predictive capabilities of ab-initio method are utilised to explore bands dispersion and charge transfer in β-BeH2. Investigations are carried out using the linear combination of atomic orbitals method at the level of density functional theory. The crystal structure and related parameters are settled by coupling total energy calculations with the Murnaghan equation of state. Electronic bands dispersion from PBE-GGA is reported. The PBE-GGA, and PBE0 hybrid functional, show that β-BeH2 is a direct gap semiconductor with 1.18 and 2.40 eV band gap. The band gap slowly decreases with pressure and beyond l00 GPa overlap of conduction and valence bands at the r point is observed. Charge transfer is studied by means of Mullikan population analysis.

  11. Non-local exchange correlation functionals impact on the structural, electronic and optical properties of III-V arsenides

    KAUST Repository

    Anua, N. Najwa

    2013-08-20

    Exchange correlation (XC) energy functionals play a vital role in the efficiency of density functional theory (DFT) calculations, more soundly in the calculation of fundamental electronic energy bandgap. In the present DFT study of III-arsenides, we investigate the implications of XC-energy functional and corresponding potential on the structural, electronic and optical properties of XAs (X = B, Al, Ga, In). Firstly we report and discuss the optimized structural lattice parameters and the band gap calculations performed within different non-local XC functionals as implemented in the DFT-packages: WIEN2k, CASTEP and SIESTA. These packages are representative of the available code in ab initio studies. We employed the LDA, GGA-PBE, GGA-WC and mBJ-LDA using WIEN2k. In CASTEP, we employed the hybrid functional, sX-LDA. Furthermore LDA, GGA-PBE and meta-GGA were employed using SIESTA code. Our results point to GGA-WC as a more appropriate approximation for the calculations of structural parameters. However our electronic bandstructure calculations at the level of mBJ-LDA potential show considerable improvements over the other XC functionals, even the sX-LDA hybrid functional. We report also the optical properties within mBJ potential, which show a nice agreement with the experimental measurements in addition to other theoretical results. © 2013 IOP Publishing Ltd.

  12. MSWT-01, an alternative in combining Production Based Education (PBE) and student CSR program in Polman

    Science.gov (United States)

    Ananto, Gamawan; Setiawan, Albertus B.; Z, Darman M.

    2014-06-01

    MSWT-01, Mobile Surface Water Treatment, producing 1m3 per hour, is an alternative for providing clean water in flood disaster areas, and was developed at Bandung State Polytechnic for Manufacturing (Polman) as a part of institution research project. The combination of cartridge or membrane technology such as carbon block, MF, UF and filtration media is used for this machine, instead of coagulation-flocculation with chemical addition, due to emergency purposes related with its treatment processing time. The idea is that MSWT could be combined with Production Based Education (PBE) concept in Polman as a vocational education institution and students 'CSR', students social activities. With the number of implementation trials in real flood area condition, MSWT will be developed further based on the technical output result. The manufacturing process for improving or adding necessary features could be implemented as a student's project in PBE system. This might be an ideal combination alternative for such vocational institution that students get the product media for their PBE program and implement their work as a defined social activity. They will learn and experience related technical matters and more social interactions with the people and other disaster stakeholder as well.

  13. Systematic study of low-mass electron pair production in p-Be and p-Au collisions at 450 GeV/c

    NARCIS (Netherlands)

    Agakichiev, G; Appenheimer, M; Averbeck, R; Ballester, F; Baur, R; Brenschede, A; Diaz, J; Drees, A; Faschingbauer, U; Ferrero, JL; Fraenkel, Z; Franke, M; Fuchs, C; Gatti, E; Glassel, P; Gunzel, T; de los Heros, CP; Hess, F; Holzmann, R; Iourevitch, [No Value; Irmscher, D; Jacob, C; Kuhn, W; Lenkeit, B; Löhner, H.; Marin, A; Marques, FM; Martinez, G; Metag, [No Value; Notheisen, M; Novotny, R; Olsen, LH; Ostendorf, R; Panebrattsev, Y; Pfeiffer, A; Ravinovich, [No Value; Rehak, P; Sampietro, M; Schon, A; Schukraft, J; Schutz, Y; Shimansky, S; Shor, A; Simon, RS; Specht, HJ; Steiner, [No Value; Tapprogge, S; Tel-Zur, G; Tserruya, [No Value; Ullrich, T; Wilschut, H.; Wurm, JP

    In a joint effort the CERES/NA45 and TAPS collaborations have measured low-mass electron pairs in p-Be and p-Au collisions at 450 GeV/c at the CERN SPS. In the range covered up to approximate to 1.5 GeV/c(2) the mass spectra from p-Be and p-Au collisions are well explained by electron pairs from

  14. Density-functional theory for f-electron systems. The α-γ phase transition in cerium

    International Nuclear Information System (INIS)

    Casadei, Marco

    2013-01-01

    Rare earths are technologically important and scientifically highly interesting elements. The description of the volume collapse exhibited by some rare earth metals poses a great challenge to density-functional theory (DFT) since local/semi-local functionals (LDA/GGA) only partially capture the associated phase transitions. In this work this problem is approached by treating all electrons at the same quantum mechanical level, using both hybrid functionals (e.g. PBE0 and HSE06) and exact-exchange plus correlation in the random-phase approximation (EX+cRPA). The performance of recently developed beyond RPA schemes is also assessed. The isostructural α-γ phase transition in cerium is the most studied. The exact exchange contribution in PBE0 and HSE06 is crucial to produce two distinct solutions that can be associated with the α and γ phases. The two solutions emerge in bulk as well as in cluster calculations. Most notable is their presence in the cerium dimer. However, quantitative agreement with the extrapolated phase diagram requires EX+cRPA. So far the EX+cRPA correction can only be applied to cerium clusters and not to the bulk. A cluster of 19 atoms cut from the fcc crystal structure (the same that characterizes the α and γ phases) was therefore determined as representative. (EX+cRPA) rate at PBE0 for Ce 19 provides good agreement with the extrapolated transition pressure to zero temperature. We predict that a pressure induced phase transition should exist at or close to zero. A finite temperature phase diagram can be drawn in reasonable agreement with experiment by adding entropic effects. The cerium neighbors are also studied: lanthanum, which has no f electrons, praseodymium, with three f electrons and a volume collapse, and neodymium, with four f electrons and no volume collapse. Multiple solutions are also present for these f electron elements, confirming the importance of exact-exchange for f electron systems.

  15. Improved adsorption energetics within density-functional theory using revised Perdew-Burke-Ernzerhof functionals

    DEFF Research Database (Denmark)

    Hammer, Bjørk; Hansen, Lars Bruno; Nørskov, Jens Kehlet

    1999-01-01

    A simple formulation of a generalized gradient approximation for the exchange and correlation energy of electrons has been proposed by Perdew, Burke, and Ernzerhof (PBE) [Phys. Rev. Lett. 77, 3865 (1996)]. Subsequently Zhang and Yang [Phys. Rev. Lett. 80, 890 (1998)] have shown that a slight...... revision of the PBE functional systematically improves the atomization energies for a large database of small molecules. In the present work, we show that the Zhang and Yang functional (revPBE) also improves the chemisorption energetics of atoms and molecules on transition-metal surfaces. Our test systems...

  16. Long-range corrected density functional theory with accelerated Hartree-Fock exchange integration using a two-Gaussian operator [LC-ωPBE(2Gau)].

    Science.gov (United States)

    Song, Jong-Won; Hirao, Kimihiko

    2015-10-14

    Since the advent of hybrid functional in 1993, it has become a main quantum chemical tool for the calculation of energies and properties of molecular systems. Following the introduction of long-range corrected hybrid scheme for density functional theory a decade later, the applicability of the hybrid functional has been further amplified due to the resulting increased performance on orbital energy, excitation energy, non-linear optical property, barrier height, and so on. Nevertheless, the high cost associated with the evaluation of Hartree-Fock (HF) exchange integrals remains a bottleneck for the broader and more active applications of hybrid functionals to large molecular and periodic systems. Here, we propose a very simple yet efficient method for the computation of long-range corrected hybrid scheme. It uses a modified two-Gaussian attenuating operator instead of the error function for the long-range HF exchange integral. As a result, the two-Gaussian HF operator, which mimics the shape of the error function operator, reduces computational time dramatically (e.g., about 14 times acceleration in C diamond calculation using periodic boundary condition) and enables lower scaling with system size, while maintaining the improved features of the long-range corrected density functional theory.

  17. The nature of excess electrons in anatase and rutile from hybrid DFT and RPA.

    Science.gov (United States)

    Spreafico, Clelia; VandeVondele, Joost

    2014-12-21

    The behavior of excess electrons in undoped and defect free bulk anatase and rutile TiO2 has been investigated by state-of-the-art electronic structure methods including hybrid density functional theory (DFT) and the random phase approximation (RPA). Consistent with experiment, charge trapping and polaron formation is observed in both anatase and rutile. The difference in the anisotropic shape of the polarons is characterized, confirming for anatase the large polaron picture. For anatase, where polaron formation energies are small, charge trapping is observed also with standard hybrid functionals, provided the simulation cell is sufficiently large (864 atoms) to accommodate the lattice relaxation. Even though hybrid orbitals are required as a starting point for RPA in this system, the obtained polaron formation energies are relatively insensitive to the amount of Hartree-Fock exchange employed. The difference in trapping energy between rutile and anatase can be obtained accurately with both hybrid functionals and RPA. Computed activation energies for polaron hopping and delocalization clearly show that anatase and rutile might have different charge transport mechanisms. In rutile, only hopping is likely, whereas in anatase hopping and delocalization are competing. Delocalization will result in conduction-band-like and thus enhanced transport. Anisotropic conduction, in agreement with experimental data, is observed, and results from the tendency to delocalize in the [001] direction in rutile and the (001) plane in anatase. For future work, our calculations serve as a benchmark and suggest RPA on top on hybrid orbitals (PBE0 with 30% Hartree-Fock exchange), as a suitable method to study the rich chemistry and physics of TiO2.

  18. Density Functional Theory Calculation of the Band Alignment of (101̅0) In(x)Ga(1-x)N/Water Interfaces.

    Science.gov (United States)

    Meng, Andrew C; Cheng, Jun; Sprik, Michiel

    2016-03-03

    Conduction band edge (CBE) and valence band edge (VBE) positions of InxGa1-xN photoelectrodes were computed using density functional theory methods. The band edges of fully solvated GaN and InN model systems were aligned with respect to the standard hydrogen electrode using a molecular dynamics hydrogen electrode scheme applied earlier to TiO2/water interfaces. Similar to the findings for TiO2, we found that the Purdew-Burke-Ernzerhof (PBE) functional gives a VBE potential which is too negative by 1 V. This cathodic bias is largely corrected by application of the Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional containing a fraction of Hartree-Fock exchange. The effect of a change of composition was investigated using simplified model systems consisting of vacuum slabs covered on both sides by one monolayer of H2O. The CBE was found to vary linearly with In content. The VBE, in comparison, is much less sensitive to composition. The data show that the band edges straddle the hydrogen and oxygen evolution potentials for In fractions less than 47%. The band gap was found to exceed 2 eV for an In fraction less than 54%.

  19. First-principles study of MoS2 and MoSe2 nanoclusters in the framework of evolutionary algorithm and density functional theory

    Science.gov (United States)

    Hashemi, Zohreh; Rafiezadeh, Shohreh; Hafizi, Roohollah; Hashemifar, S. Javad; Akbarzadeh, Hadi

    2018-04-01

    Evolutionary algorithm is combined with full-potential ab initio calculations to investigate conformational space of (MoS2)n and (MoSe2)n (n = 1-10) nanoclusters and to identify the lowest energy structural isomers of these systems. It is argued that within both BLYP and PBE functionals, these nanoclusters favor sandwiched planar configurations, similar to their ideal planar sheets. The second order difference in total energy (Δ2 E) of the lowest energy isomers is computed to estimate the abundance of the clusters at different sizes and to determine the magic sizes of (MoS2)n and (MoSe2)n nanoclusters. In order to investigate the electronic properties of nanoclusters, their energy gap is calculated by several methods, including hybrid functionals (B3LYP and PBE0), GW approach, and Δ scf method. At the end, the vibrational modes of the lowest lying isomers are calculated by using the force constants method and the IR active modes of the systems are identified. The vibrational spectra are used to calculate the Helmholtz free energy of the systems and then to investigate abundance of the nanoclusters at finite temperatures.

  20. Density functional theory calculations on alkali and the alkaline Ca atoms adsorbed on graphene monolayers

    International Nuclear Information System (INIS)

    Dimakis, Nicholas; Valdez, Danielle; Flor, Fernando Antonio; Salgado, Andres; Adjibi, Kolade; Vargas, Sarah; Saenz, Justin

    2017-01-01

    Highlights: • Li, K, Na, and Ca graphene interaction is primarily ionic, whereas small covalent interactions also co-exist in these cases. • Van der Waals interactions are revealed by comparing adatom-graphene geometries between 1.4% and 3% adatom coverages and using Grimme corrections. • The Li, K, Na graphene interactions are accurately described by both PBE0 and PBE functionals. For Ca/graphene, the PBE0 functional should not be used. • For Li, K, and Na adsorbed on graphene, adatom-graphene interaction weakens as the adatom coverages increases. • The Ca-graphene interaction strength, which is stronger at high coverages, is opposite to increases in the Ca–4s orbital population. - Abstract: The adsorption of the alkali Li, K, and Na and the alkaline Ca on graphene is studied using periodic density functional theory (DFT) under various adatom coverages. The charge transfers between the adatom and the graphene sheet and the almost unchanged densities-of-states spectra in the energy region near and below the Fermi level support an ionic bond pattern between the adatom and the graphene atoms. However, the presence of small orbital overlap between the metal and the nearest graphene atom is indicative of small covalent bonding. Van der Waals interactions are examined through a semiempirical correction in the DFT functional and by comparing adatom-graphene calculations between 3% and 1.4% adatom coverages. Optimized adatom-graphene geometries identify the preferred adatom sites, whereas the adatom-graphene strength is correlated with the adsorption energy and the adatom distance from the graphene plane. Calculated electronic properties and structural parameters are obtained using hybrid functionals and a generalized gradient approximation functional paired with basis sets of various sizes. We found that due to long range electrostatic forces between the alkali/alkaline adatoms and the graphene monolayer, the adatom-graphene structural and electronic

  1. Density functional theory calculations on alkali and the alkaline Ca atoms adsorbed on graphene monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, Nicholas, E-mail: nicholas.dimakis@utrgv.edu [Department of Physics, University of Texas Rio Grande Valley, Edinburg, TX (United States); Valdez, Danielle; Flor, Fernando Antonio; Salgado, Andres; Adjibi, Kolade [Department of Physics, University of Texas Rio Grande Valley, Edinburg, TX (United States); Vargas, Sarah; Saenz, Justin [Robert Vela High School, Edinburg, TX (United States)

    2017-08-15

    Highlights: • Li, K, Na, and Ca graphene interaction is primarily ionic, whereas small covalent interactions also co-exist in these cases. • Van der Waals interactions are revealed by comparing adatom-graphene geometries between 1.4% and 3% adatom coverages and using Grimme corrections. • The Li, K, Na graphene interactions are accurately described by both PBE0 and PBE functionals. For Ca/graphene, the PBE0 functional should not be used. • For Li, K, and Na adsorbed on graphene, adatom-graphene interaction weakens as the adatom coverages increases. • The Ca-graphene interaction strength, which is stronger at high coverages, is opposite to increases in the Ca–4s orbital population. - Abstract: The adsorption of the alkali Li, K, and Na and the alkaline Ca on graphene is studied using periodic density functional theory (DFT) under various adatom coverages. The charge transfers between the adatom and the graphene sheet and the almost unchanged densities-of-states spectra in the energy region near and below the Fermi level support an ionic bond pattern between the adatom and the graphene atoms. However, the presence of small orbital overlap between the metal and the nearest graphene atom is indicative of small covalent bonding. Van der Waals interactions are examined through a semiempirical correction in the DFT functional and by comparing adatom-graphene calculations between 3% and 1.4% adatom coverages. Optimized adatom-graphene geometries identify the preferred adatom sites, whereas the adatom-graphene strength is correlated with the adsorption energy and the adatom distance from the graphene plane. Calculated electronic properties and structural parameters are obtained using hybrid functionals and a generalized gradient approximation functional paired with basis sets of various sizes. We found that due to long range electrostatic forces between the alkali/alkaline adatoms and the graphene monolayer, the adatom-graphene structural and electronic

  2. Ground-State Gas-Phase Structures of Inorganic Molecules Predicted by Density Functional Theory Methods

    KAUST Repository

    Minenkov, Yury

    2017-11-29

    We tested a battery of density functional theory (DFT) methods ranging from generalized gradient approximation (GGA) via meta-GGA to hybrid meta-GGA schemes as well as Møller–Plesset perturbation theory of the second order and a single and double excitation coupled-cluster (CCSD) theory for their ability to reproduce accurate gas-phase structures of di- and triatomic molecules derived from microwave spectroscopy. We obtained the most accurate molecular structures using the hybrid and hybrid meta-GGA approximations with B3PW91, APF, TPSSh, mPW1PW91, PBE0, mPW1PBE, B972, and B98 functionals, resulting in lowest errors. We recommend using these methods to predict accurate three-dimensional structures of inorganic molecules when intramolecular dispersion interactions play an insignificant role. The structures that the CCSD method predicts are of similar quality although at considerably larger computational cost. The structures that GGA and meta-GGA schemes predict are less accurate with the largest absolute errors detected with BLYP and M11-L, suggesting that these methods should not be used if accurate three-dimensional molecular structures are required. Because of numerical problems related to the integration of the exchange–correlation part of the functional and large scattering of errors, most of the Minnesota models tested, particularly MN12-L, M11, M06-L, SOGGA11, and VSXC, are also not recommended for geometry optimization. When maintaining a low computational budget is essential, the nonseparable gradient functional N12 might work within an acceptable range of error. As expected, the DFT-D3 dispersion correction had a negligible effect on the internuclear distances when combined with the functionals tested on nonweakly bonded di- and triatomic inorganic molecules. By contrast, the dispersion correction for the APF-D functional has been found to shorten the bonds significantly, up to 0.064 Å (AgI), in Ag halides, BaO, BaS, BaF, BaCl, Cu halides, and Li and

  3. 76 FR 435 - Airworthiness Directives; B/E Aerospace Protective Breathing Equipment (PBE) Part Number 119003...

    Science.gov (United States)

    2011-01-05

    ... Airworthiness Directives; B/E Aerospace Protective Breathing Equipment (PBE) Part Number 119003-11 Installed on... February 9, 2011. ADDRESSES: For service information identified in this AD, contact B/E Aerospace, Inc... Jersey Avenue, SE., Washington, DC 20590. FOR FURTHER INFORMATION CONTACT: David Fairback, Aerospace...

  4. Benchmark fragment-based 1H, 13C, 15N and 17O chemical shift predictions in molecular crystals†

    Science.gov (United States)

    Hartman, Joshua D.; Kudla, Ryan A.; Day, Graeme M.; Mueller, Leonard J.; Beran, Gregory J. O.

    2016-01-01

    The performance of fragment-based ab initio 1H, 13C, 15N and 17O chemical shift predictions is assessed against experimental NMR chemical shift data in four benchmark sets of molecular crystals. Employing a variety of commonly used density functionals (PBE0, B3LYP, TPSSh, OPBE, PBE, TPSS), we explore the relative performance of cluster, two-body fragment, and combined cluster/fragment models. The hybrid density functionals (PBE0, B3LYP and TPSSh) generally out-perform their generalized gradient approximation (GGA)-based counterparts. 1H, 13C, 15N, and 17O isotropic chemical shifts can be predicted with root-mean-square errors of 0.3, 1.5, 4.2, and 9.8 ppm, respectively, using a computationally inexpensive electrostatically embedded two-body PBE0 fragment model. Oxygen chemical shieldings prove particularly sensitive to local many-body effects, and using a combined cluster/fragment model instead of the simple two-body fragment model decreases the root-mean-square errors to 7.6 ppm. These fragment-based model errors compare favorably with GIPAW PBE ones of 0.4, 2.2, 5.4, and 7.2 ppm for the same 1H, 13C, 15N, and 17O test sets. Using these benchmark calculations, a set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided and their robustness assessed using statistical cross-validation. We demonstrate the utility of these approaches and the reported scaling parameters on applications to 9-tertbutyl anthracene, several histidine co-crystals, benzoic acid and the C-nitrosoarene SnCl2(CH3)2(NODMA)2. PMID:27431490

  5. Benchmark fragment-based (1)H, (13)C, (15)N and (17)O chemical shift predictions in molecular crystals.

    Science.gov (United States)

    Hartman, Joshua D; Kudla, Ryan A; Day, Graeme M; Mueller, Leonard J; Beran, Gregory J O

    2016-08-21

    The performance of fragment-based ab initio(1)H, (13)C, (15)N and (17)O chemical shift predictions is assessed against experimental NMR chemical shift data in four benchmark sets of molecular crystals. Employing a variety of commonly used density functionals (PBE0, B3LYP, TPSSh, OPBE, PBE, TPSS), we explore the relative performance of cluster, two-body fragment, and combined cluster/fragment models. The hybrid density functionals (PBE0, B3LYP and TPSSh) generally out-perform their generalized gradient approximation (GGA)-based counterparts. (1)H, (13)C, (15)N, and (17)O isotropic chemical shifts can be predicted with root-mean-square errors of 0.3, 1.5, 4.2, and 9.8 ppm, respectively, using a computationally inexpensive electrostatically embedded two-body PBE0 fragment model. Oxygen chemical shieldings prove particularly sensitive to local many-body effects, and using a combined cluster/fragment model instead of the simple two-body fragment model decreases the root-mean-square errors to 7.6 ppm. These fragment-based model errors compare favorably with GIPAW PBE ones of 0.4, 2.2, 5.4, and 7.2 ppm for the same (1)H, (13)C, (15)N, and (17)O test sets. Using these benchmark calculations, a set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided and their robustness assessed using statistical cross-validation. We demonstrate the utility of these approaches and the reported scaling parameters on applications to 9-tert-butyl anthracene, several histidine co-crystals, benzoic acid and the C-nitrosoarene SnCl2(CH3)2(NODMA)2.

  6. Local hybrid functionals: An assessment for thermochemical kinetics

    International Nuclear Information System (INIS)

    Kaupp, Martin; Bahmann, Hilke; Arbuznikov, Alexei V.

    2007-01-01

    Local hybrid functionals with position-dependent exact-exchange admixture are a new class of exchange-correlation functionals in density functional theory that promise to advance the available accuracy in many areas of application. Local hybrids with different local mixing functions (LMFs) governing the position dependence are validated for the heats of formation of the extended G3/99 set, and for two sets of barriers of hydrogen-transfer and heavy-atom transfer reactions (HTBH38 and NHTBH38 databases). A simple local hybrid Lh-SVWN with only Slater and exact exchange plus local correlation and a one-parameter LMF, g(r)=b(τ W (r)/τ(r)), performs best and provides overall mean absolute errors for thermochemistry and kinetics that are a significant improvement over standard state-of-the-art global hybrid functionals. In particular, this local hybrid functional does not suffer from the systematic deterioration that standard functionals exhibit for larger molecules. In contrast, local hybrids based on generalized gradient approximation exchange tend to give rise to nonintuitive LMFs, and no improved functionals have been obtained along this route. The LMF is a real-space function and thus can be analyzed in detail. We use, in particular, graphical analyses to rationalize the performance of different local hybrids for thermochemistry and reaction barriers

  7. Optimizing the structure of Tetracyanoplatinate(II)

    DEFF Research Database (Denmark)

    Dohn, Asmus Ougaard; Møller, Klaus Braagaard; Sauer, Stephan P. A.

    2013-01-01

    . For the C-N bond these trends are reversed and an order of magnitude smaller. With respect to the basis set dependence we observed that a triple zeta basis set with polarization functions gives in general sufficiently converged results, but while for the Pt-C bond it is advantageous to include extra diffuse......The geometry of tetracyanoplatinate(II) (TCP) has been optimized with density functional theory (DFT) calculations in order to compare different computational strategies. Two approximate scalar relativistic methods, i.e. the scalar zeroth-order regular approximation (ZORA) and non...... is almost quantitatively reproduced in the ZORA and ECP calculations. In addition, the effect of the exchange-correlation functional and one-electron basis set was studied by employing the two generalized gradient approximation (GGA) functionals, BLYP and PBE, as well as their hybrid version B3LYP and PBE0...

  8. Effects of side-chain and electron exchange correlation on the band structure of perylene diimide liquid crystals: a density functional study.

    Science.gov (United States)

    Arantes, J T; Lima, M P; Fazzio, A; Xiang, H; Wei, Su-Huai; Dalpian, G M

    2009-04-23

    The structural and electronic properties of perylene diimide liquid crystal PPEEB are studied using ab initio methods based on the density functional theory (DFT). Using available experimental crystallographic data as a guide, we propose a detailed structural model for the packing of solid PPEEB. We find that due to the localized nature of the band edge wave function, theoretical approaches beyond the standard method, such as hybrid functional (PBE0), are required to correctly characterize the band structure of this material. Moreover, unlike previous assumptions, we observe the formation of hydrogen bonds between the side chains of different molecules, which leads to a dispersion of the energy levels. This result indicates that the side chains of the molecular crystal not only are responsible for its structural conformation but also can be used for tuning the electronic and optical properties of these materials.

  9. Neutral meson production in $p$-Be and $p$-Au collisions at 450 GeV beam energy

    CERN Document Server

    Agakichiev, G; Averbeck, R; Ballester, F; Baur, R; Brenschede, A; Díaz, J; Drees, A; Faschingbauer, U; Ferrero, J L; Fischer, P; Fraenkel, Zeev; Franke, M; Fuchs, C; Gatti, E; Glässel, P; Günzel, T F; Pérez de los Heros, C; Hess, F; Holzmann, R; Irmscher, D; Jacob, C; Kühn, W; Lenkeit, B C; Löhner, H; Marin, A; Marqués, F M; Martínez, G; Metag, V; Notheisen, M; Novotny, R; Olsen, L H; Ostendorf, R W; Panebratsev, Yu A; Pfeiffer, A; Ravinovich, I; Rehak, P; Sampietro, M; Schön, A; Schükraft, Jürgen; Schutz, Y; Shimansky, S S; Shor, A; Simon, R S; Specht, H J; Steiner, V; Tapprogge, Stefan; Tel-Zur, G; Tserruya, Itzhak; Ullrich, T S; Wilschut, H W; Wurm, J P; Yurevich, V I

    1998-01-01

    In a joint experiment the TAPS and CERES collaborations have studied the production of the neutral mesons $\\pi^{0}$, $\\eta$ and $\\omega$ in 450 GeV $p$-Be and $p$-Au collisions at the CERN SPS. The mesons were identified by their $\\pi^{0} \\rightarrow \\gamma\\gamma, \\eta \\rightarrow \\gamma\\gamma$, and $\\omega \\rightarrow \\pi^{0}\\gamma$ decay modes. The cross sections were measured down to very low $p_{T}$ ($\\geq$ 20 MeV/c) near mid-rapidity $(3.00)$. The $\\eta$ and $\\omega$ cross sections are smaller than expected from extrapolations of earlier data to low $p_{T}$. Integrated over all $p_{T}$, the ratios $\\eta/\\pi^{0}$ and $\\omega/\\pi^{0}$ are lower by about 25% compared to previously published values. The reduction may be attributed to the large number of low $p_{T}$ pions from decays of heavier mesons. In addition, we have studied the dependence of neutral meson production on the mass of the nuclear target and find it in good agreement with previous measurements of charged mesons.

  10. Quantifying the Performances of DFT for Predicting Vibrationally Resolved Optical Spectra: Asymmetric Fluoroborate Dyes as Working Examples.

    Science.gov (United States)

    Bednarska, Joanna; Zaleśny, Robert; Bartkowiak, Wojciech; Ośmiałowski, Borys; Medved', Miroslav; Jacquemin, Denis

    2017-09-12

    This article aims at a quantitative assessment of the performances of a panel of exchange-correlation functionals, including semilocal (BLYP and PBE), global hybrids (B3LYP, PBE0, M06, BHandHLYP, M06-2X, and M06-HF), and range-separated hybrids (CAM-B3LYP, LC-ωPBE, LC-BLYP, ωB97X, and ωB97X-D), in predicting the vibrationally resolved absorption spectra of BF 2 -carrying compounds. To this end, for 19 difluoroborates as examples, we use, as a metric, the vibrational reorganization energy (λ vib ) that can be determined based on the computationally efficient linear coupling model (a.k.a. vertical gradient method). The reference values of λ vib were determined by employing the CC2 method combined with the cc-pVTZ basis set for a representative subset of molecules. To validate the performances of CC2, comparisons with experimental data have been carried out as well. This study shows that the vibrational reorganization energy, involving Huang-Rhys factors and normal-mode frequencies, can indeed be used to quantify the reliability of functionals in the calculations of the vibrational fine structure of absorption bands, i.e., an accurate prediction of the vibrational reorganization energy leads to absorption band shapes better fitting the selected reference. The CAM-B3LYP, M06-2X, ωB97X-D, ωB97X, and BHandHLYP functionals all deliver vibrational reorganization energies with absolute relative errors smaller than 20% compared to CC2, whereas 10% accuracy can be achieved with the first three functionals. Indeed, the set of examined exchange-correlation functionals can be divided into three groups: (i) BLYP, B3LYP, PBE, PBE0, and M06 yield inaccurate band shapes (λ vib,TDDFT poor band topologies (λ vib,TDDFT > λ vib,CC2 ). This study also demonstrates that λ vib can be reliably estimated using the CC2 model and the relatively small cc-pVDZ basis set. Therefore, the linear coupling model combined with the CC2/cc-pVDZ level of theory can be used as a very efficient

  11. Band alignment and charge transfer predictions of ZnO/ZnX (X = S, Se or Te) interfaces applied to solar cells: a PBE+U theoretical study.

    Science.gov (United States)

    Flores, Efracio Mamani; Gouvea, Rogério Almeida; Piotrowski, Maurício Jeomar; Moreira, Mário Lucio

    2018-02-14

    The engineering of semiconductor materials for the development of solar cells is of great importance today. Two topics are considered to be of critical importance for the efficiency of Grätzel-type solar cells, the efficiency of charge separation and the efficiency of charge carrier transfer. Thus, one research focus is the combination of semiconductor materials with the aim of reducing charge recombination, which occurs by spatial charge separation. From an experimental point of view, the combining of materials can be achieved by decorating a core with a shell of another material resulting in a core-shell system, which allows control of the desired photoelectronic properties. In this context, a computational simulation is mandatory for the atomistic understanding of possible semiconductor combinations and for the prediction of their properties. Considering the construction of ZnO/ZnX (X = S, Se or Te) interfaces, we seek to investigate the electronic influence of the shell (ZnX) on the core (ZnO) and, consequently, find out which of the interfaces would present the appropriate properties for (Grätzel-type) solar cell applications. To perform this study, we have employed density functional theory (DFT) calculations, considering the Perdew-Burke-Ernzerhof (PBE) functional. However, it is well-known that plain DFT fails to describe strong electronic correlated materials where, in general, an underestimation of the band gap is obtained. Thus, to obtain the correct description of the electronic properties, a Hubbard correction was employed, i.e. PBE+U calculations. The PBE+U methodology provided the correct electronic structure properties for bulk ZnO in good agreement with experimental values (99.4%). The ZnO/ZnX interfaces were built and were composed of six ZnO layers and two ZnX layers, which represents the decoration process. The core-shell band gap was 2.2 eV for ZnO/ZnS, ∼1.71 eV for ZnO/ZnSe and ∼0.95 eV for ZnO/ZnTe, which also exhibited a type-II band

  12. Neutral meson production in p-Be and p-Au collisions at 450 GeV beam energy

    NARCIS (Netherlands)

    Agakichiev, G; Appenheimer, M; Averbeck, R; Ballester, F; Baur, R; Brenschede, A; Diaz, J; Drees, A; Faschingbauer, U; Ferrero, JL; Fraenkel, Z; Franke, M; Fuchs, C; Gatti, E; Glassel, P; Gunzel, T; de los Hero, CP; Hess, F.; Holzmann, R; Irmscher, D; Jacob, C; Kuhn, W; Lenkeit, B; Löhner, H.; Marin, A; Marques, FM; Martinez, G; Metag, [No Value; Notheisen, M; Novotny, R; Olsen, LH; Schon, A; Schukraft, J; Ostendorf, R.; Panebrattsev, Y; Pfeiffer, A; Ravinovich, [No Value; Rehak, P; Sampietro, M; Schutz, Y; Shimansky, S; Shor, A; Simon, RS; Specht, HJ; Steiner, [No Value; Tapprogge, S; Tel-Zur, G; Tserruya, [No Value; Ullrich, T; Wilschut, H.; Wurm, JP; Yurevich, [No Value

    In a joint experiment the TAPS and CERES collaborations have studied the production of the neutral mesons pi degrees; eta and omega in 450 GeV p-Be and p-Au collisions at the CERN SPS. The mesons were identified by their pi degrees --> gamma gamma, eta --> gamma gamma, and omega --> pi degrees gamma

  13. Fragment-based {sup 13}C nuclear magnetic resonance chemical shift predictions in molecular crystals: An alternative to planewave methods

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, Joshua D.; Beran, Gregory J. O., E-mail: gregory.beran@ucr.edu [Department of Chemistry, University of California, Riverside, California 92521 (United States); Monaco, Stephen; Schatschneider, Bohdan [The Pennsylvania State University, The Eberly Campus, 2201 University Dr, Lemont Furnace, Pennsylvania 15456 (United States)

    2015-09-14

    We assess the quality of fragment-based ab initio isotropic {sup 13}C chemical shift predictions for a collection of 25 molecular crystals with eight different density functionals. We explore the relative performance of cluster, two-body fragment, combined cluster/fragment, and the planewave gauge-including projector augmented wave (GIPAW) models relative to experiment. When electrostatic embedding is employed to capture many-body polarization effects, the simple and computationally inexpensive two-body fragment model predicts both isotropic {sup 13}C chemical shifts and the chemical shielding tensors as well as both cluster models and the GIPAW approach. Unlike the GIPAW approach, hybrid density functionals can be used readily in a fragment model, and all four hybrid functionals tested here (PBE0, B3LYP, B3PW91, and B97-2) predict chemical shifts in noticeably better agreement with experiment than the four generalized gradient approximation (GGA) functionals considered (PBE, OPBE, BLYP, and BP86). A set of recommended linear regression parameters for mapping between calculated chemical shieldings and observed chemical shifts are provided based on these benchmark calculations. Statistical cross-validation procedures are used to demonstrate the robustness of these fits.

  14. Computational study of An-X bonding (An = Th, U; X = p-block-based ligands) in pyrrolic macrocycle-supported complexes from the quantum theory of atoms in molecules and bond energy decomposition analysis.

    Science.gov (United States)

    O'Brien, Kieran T P; Kaltsoyannis, Nikolas

    2017-01-17

    A systematic computational study of organoactinide complexes of the form [LAnX] n+ has been carried out using density functional theory, the quantum theory of atoms in molecules (QTAIM) and Ziegler-Rauk energy decomposition analysis (EDA) methods. The systems studied feature L = trans-calix[2]benzene[2]pyrrolide, An = Th(iv), Th(iii), U(iii) and X = BH 4 , BO 2 C 2 H 4 , Me, N(SiH 3 ) 2 , OPh, CH 3 , NH 2 , OH, F, SiH 3 , PH 2 , SH, Cl, CH 2 Ph, NHPh, OPh, SiH 2 Ph, PHPh 2 , SPh, CPh 3 , NPh 2 , OPh, SiPh 3 PPh 2 , SPh. The PBE0 hybrid functional proved most suitable for geometry optimisations based on comparisons with available experimental data. An-X bond critical point electron densities, energy densities and An-X delocalisation indices, calculated with the PBE functional at the PBE0 geometries, are correlated with An-X bond energies, enthalpies and with the terms in the EDA. Good correlations are found between energies and QTAIM metrics, particularly for the orbital interaction term, provided the X ligand is part of an isoelectronic series and the number of open shell electrons is low (i.e. for the present Th(iv) and Th(iii) systems).

  15. Ni-doping effect of Mg(0 0 0 1) surface to use it as a hydrogen storage material

    International Nuclear Information System (INIS)

    Kuklin, Artem V.; Kuzubov, Alexander A.; Krasnov, Pavel O.; Lykhin, Aleksandr O.; Tikhonova, Lyudmila V.

    2014-01-01

    Highlights: • Magnesium surface interaction with nickel at different it location was investigated. • A possibility of nickel migration on magnesium surface was examined. • A possibility of the nickel atoms to aggregate, producing the cluster was investigated. • A step by step diagram of the cluster formation was calculated and constructed. • The final step was the investigation of a hydrogenation process on the Ni cluster. - Abstract: A detailed study of Ni-doped Mg(0 0 0 1) surface performed by PAW method and the gradient corrected density functional GGA-PBE within the framework of generalized Kohn–Sham density functional theory (DFT) is presented in this work. Structural and electronic properties of magnesium surface interaction with nickel for the purpose of such compounds use for creation of hydrogen storage matrixes were investigated here. Choice of the PBE functional was caused by the good accordance of its prediction of the cell parameters with experimental results. It was shown that Ni atoms prefer to substitute for Mg atoms. Using NEB method, the diffusion barrier was calculated, and the most probable reaction path was established. In particular, when the Ni atom dopes the magnesium surface, it can migrate to the bulk and substitute for Mg in subsurface layers. Also a possibility of nickel cluster formation on clean surface of magnesium was examined. The kinetic factors hinder the movement of the nickel atoms to each other and make problematic the formation of clusters. The studies presented here showed that the diffusion barriers of the nickel atom migration from the cluster on the surface to the bulk of magnesium are 1.179 eV and 1.211 eV for the forward and reverse reactions, respectively. Therefore an improvement of the hydrogenation properties of Ni-doped magnesium surface depends on deposition not of the individual atoms, but their clusters. Hydrogenation of Ni cluster doping the magnesium surface was investigated. Initially Kubas

  16. Performance analysis of hybrid ground-coupled heat pump system with multi-functions

    International Nuclear Information System (INIS)

    You, Tian; Wang, Baolong; Wu, Wei; Shi, Wenxing; Li, Xianting

    2015-01-01

    Highlights: • The hybrid GCHP system with multi-functions is proposed. • The system maintains the soil temperature and heating reliability steady. • The multi-functional operation of HCUT can save more energy of the system. - Abstract: Underground thermal imbalance is a significant problem for ground-coupled heat pump (GCHP) systems that serve predominately heated buildings in cold regions, which extract more heat from the ground and inject less heat, especially in buildings requiring domestic hot water (DHW). To solve this problem, a previously developed heat compensation unit with thermosyphon (HCUT) is integrated with a GCHP unit to build a hybrid GCHP system. To improve the energy savings of this hybrid GCHP system, the HCUT unit is set to have multiple functions (heat compensation, direct DHW and direct space heating) in this paper. To analyze the improved system performance, a hotel requiring air-conditioning and DHW is selected and simulated in three typical cold cities using the dynamic software DeST and TRNSYS. The results indicate that the hybrid GCHP system can maintain the underground thermal balance while keeping the indoor air temperature within the design range. Furthermore, the HCUT unit efficiently reduces the energy consumption via its multi-functional operations. Compared to the previous system that only used HCUT for heat compensation, adding the direct DHW function further saves 7.5–11.0% energy in heat compensation (HC) and DHW (i.e., 3.6–4.8% of the whole system). Simultaneously adding the direct DHW and space heating functions to the HCUT can save 9.8–12.9% energy in HC and DHW (i.e., 5.1–6.0% of the whole system). The hybrid GCHP system with a multi-functional HCUT provides more energy savings while maintaining the underground thermal balance in cold regions that demand both air-conditioning and DHW

  17. The GMAO Hybrid Ensemble-Variational Atmospheric Data Assimilation System: Version 2.0

    Science.gov (United States)

    Todling, Ricardo; El Akkraoui, Amal

    2018-01-01

    should point out that Release 1.0 of this document was made available to GMAO in mid-2013, when we introduced Hybrid 3D-Var capability to GEOS ADAS. This initial version of the documentation included a considerably different state-of-science introductory section but many of the same detailed description of the mechanisms of GEOS EnADAS. We are glad to report that a few of the desirable Future Works listed in Release 1.0 have now been added to the present version of GEOS EnADAS. These include the ability to exercise an Ensemble Prediction System that uses the ensemble analyses of GEOS EnADAS and (a very early, but functional version of) a tool to support Ensemble Forecast Sensitivity and Observation Impact applications.

  18. Benchmarking fully analytic DFT force fields for vibrational spectroscopy: A study on halogenated compounds

    Science.gov (United States)

    Pietropolli Charmet, Andrea; Cornaton, Yann

    2018-05-01

    This work presents an investigation of the theoretical predictions yielded by anharmonic force fields having the cubic and quartic force constants are computed analytically by means of density functional theory (DFT) using the recursive scheme developed by M. Ringholm et al. (J. Comput. Chem. 35 (2014) 622). Different functionals (namely B3LYP, PBE, PBE0 and PW86x) and basis sets were used for calculating the anharmonic vibrational spectra of two halomethanes. The benchmark analysis carried out demonstrates the reliability and overall good performances offered by hybrid approaches, where the harmonic data obtained at the coupled cluster with single and double excitations level of theory augmented by a perturbational estimate of the effects of connected triple excitations, CCSD(T), are combined with the fully analytic higher order force constants yielded by DFT functionals. These methods lead to reliable and computationally affordable calculations of anharmonic vibrational spectra with an accuracy comparable to that yielded by hybrid force fields having the anharmonic force fields computed at second order Møller-Plesset perturbation theory (MP2) level of theory using numerical differentiation but without the corresponding potential issues related to computational costs and numerical errors.

  19. Mechanical Behavior of Nanostructured Hybrids Based on Poly(Vinyl Alcohol/Bioactive Glass Reinforced with Functionalized Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    H. S. Mansur

    2012-01-01

    Full Text Available This study reports the synthesis and characterization of novel tridimensional porous hybrids based on PVA combined with bioactive glass and reinforced by chemically functionalized carbon nanotubes (CNT for potential use in bone tissue engineering. The functionalization of CNT was performed by introducing carboxylic groups in multiwall nanotubes. This process aimed at enhancing the affinity of CNTs with the water-soluble PVA polymer derived by the hydrogen bonds formed among alcohol (PVA and carboxylic groups (CNT–COOH. In the sequence, the CNT–COOH (0.25 wt% were used as the nanostructure modifier for the hybrid system based on PVA associated with the bioactive glass (BaG. The mechanical properties of the nanostructured hybrids reinforced with CNT–COOH were evaluated by axial compression tests, and they were compared to reference hybrid. The averaged yield stresses of macroporous hybrids were (2.3 ± 0.9 and (4.4 ± 1.0 MPa for the reference and the CNT reinforced materials, respectively. Moreover, yield strain and Young's modulus were significantly enhanced by about 30% for the CNT–COOH hybrids. Hence, as far as the mechanical properties are concerned, the results have clearly showed the feasibility of utilizing these new hybrids reinforced with functionalized CNT in repairing cancellous bone tissues.

  20. First-principles study of crystalline and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} and the effects of stoichiometric defects

    Energy Technology Data Exchange (ETDEWEB)

    Caravati, S; Bernasconi, M [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Via R Cozzi 53, I-20125, Milano (Italy); Kuehne, T D; Parrinello, M [Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Krack, M [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)], E-mail: marco.bernasconi@mater.unimib.it

    2009-06-24

    Based on ab initio molecular dynamics simulations, we investigated the structural, electronic and vibrational properties of cubic and amorphous Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) phase change material, focusing in particular on the effects of defects in stoichiometry on the electronic properties. It turned out Ge/Sb deficiencies (excess) in the cubic phase induce a shift of the Fermi level inside the valence (conduction) bands. In contrast, the amorphous network is flexible enough to accommodate defects in stoichiometry, keeping the Fermi level pinned at the center of the bandgap (at zero temperature). Changes in the structural and electronic properties induced by the use of hybrid functionals (HSE03, PBE0) instead of gradient corrected functionals (PBE) are addressed as well. Analysis of vibrational spectra and Debye-Waller factors of cubic and amorphous GST is also presented.

  1. Fuel and coolant motions following pin failure: EPIC models and the PBE-5S experiment

    International Nuclear Information System (INIS)

    Garner, P.L.; Abramson, P.B.

    1979-01-01

    The EPIC computer code has been used to analyze the post-fuel-pin-failure behavior in the PBE-5S experiment performed at Sandia Laboratories. The effects of modeling uncertainties on the calculation are examined. The calculations indicate that the majority of the piston motion observed in the test is due to the initial pressurization of the coolant channel by fuel vapor at cladding failure. A more definitive analysis requires improvements in calculational capabilities and experiment diagnostics

  2. Hybrid inorganic-organic adsorbents Part 1: Synthesis and characterization of mesoporous zirconium titanate frameworks containing coordinating organic functionalities.

    Science.gov (United States)

    Griffith, Christopher S; De Los Reyes, Massey; Scales, Nicholas; Hanna, John V; Luca, Vittorio

    2010-12-01

    A series of functional hybrid inorganic-organic adsorbent materials have been prepared through postsynthetic grafting of mesoporous zirconium titanate xerogel powders using a range of synthesized and commercial mono-, bis-, and tris-phosphonic acids, many of which have never before been investigated for the preparation of hybrid phases. The hybrid materials have been characterized using thermogravimetric analysis, diffuse reflectance infrared (DRIFT) and 31P MAS NMR spectroscopic techniques and their adsorption properties studied using a 153Gd radiotracer. The highest level of surface functionalization (molecules/nm2) was observed for methylphosphonic acid (∼3 molecules/nm2). The level of functionalization decreased with an increase in the number of potential surface coordinating groups of the phosphonic acids. Spectral decomposition of the DRIFT and 31P MAS NMR spectra showed that each of the phosphonic acid molecules coordinated strongly to the metal oxide surface but that for the 1,1-bis-phosphonic acids and tris-phosphonic acids the coordination was highly variable resulting in a proportion of free or loosely coordinated phosphonic acid groups. Functionalization of a porous mixed metal oxide framework with the tris-methylenephosphonic acid (ATMP-ZrTi-0.33) resulted in a hybrid with the highest affinity for 153Gd3+ in nitric acid solutions across a wide range of acid concentrations. The ATMP-ZrTi-0.33 hybrid material extracted 153Gd3+ with a Kd value of 1×10(4) in 0.01 M HNO3 far exceeding that of the other hybrid phases. The unfunctionalized mesoporous mixed metal oxide had negligible affinity for Gd3+ (KdATMP-ZrTi-0.33 hybrid phase for Gd3+ has been determined to be about 0.005 mmol/g in 0.01 M HNO3. This behavior and that of the other hybrid phases suggests that the surface-bound ATMP ligand functions as a chelating ligand toward 153Gd3+ under these acidic conditions.

  3. Spin-polarized structural, elastic, electronic and magnetic properties of half-metallic ferromagnetism in V-doped ZnSe

    Energy Technology Data Exchange (ETDEWEB)

    Monir, M. El Amine.; Baltache, H. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Lab, Department of Physics, Islamia College University, Peshawar (Pakistan); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria); Ahmed, Waleed K. [ERU, Faculty of Engineering, United Arab Emirates University, Al Ain (United Arab Emirates); Bouhemadou, A. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Omran, S. Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Seddik, T. [Laboratoire de Physique Quantique de la Matière et de la Modélisation Mathématique (LPQ3M), Faculté des Sciences, Université de Mascara, Mascara 29000 (Algeria)

    2015-01-15

    Based on first principles spin-polarized density functional theory, the structural, elastic electronic and magnetic properties of Zn{sub 1−x}V{sub x}Se (for x=0.25, 0.50, 0.75) in zinc blende structure have been studied. The investigation was done using the full-potential augmented plane wave method as implemented in WIEN2k code. The exchange-correlation potential was treated with the generalized gradient approximation PBE-GGA for the structural and elastic properties. Moreover, the PBE-GGA+U approximation (where U is the Hubbard correlation terms) is employed to treat the “d” electrons properly. A comparative study between the band structures, electronic structures, total and partial densities of states and local moments calculated within both GGA and GGA+U schemes is presented. The analysis of spin-polarized band structure and density of states shows the half-metallic ferromagnetic character and are also used to determine s(p)-d exchange constants N{sub 0}α (conduction band ) and N{sub 0}β (valence band) due to Se(4p)–V(3d) hybridization. It has been clearly evidence that the magnetic moment of V is reduced from its free space change value of 3 µ{sub B} and the minor atomic magnetic moment on Zn and Se are generated. - Highlights: • Half metallicity origins by doping V in ZnSe. • PBE-GGA+U approximation is employed to treat the “d” electrons properly. • s(p)-d Exchange constants N{sub 0}α (conduction band ) and N{sub 0}β (valence band) are due to Se(4p)-V(3d) hybridization.

  4. A multiconfigurational hybrid density-functional theory

    DEFF Research Database (Denmark)

    Sharkas, Kamal; Savin, Andreas; Jensen, Hans Jørgen Aagaard

    2012-01-01

    We propose a multiconfigurational hybrid density-functional theory which rigorously combines a multiconfiguration self-consistent-field calculation with a density-functional approximation based on a linear decomposition of the electron-electron interaction. This gives a straightforward extension ...

  5. Maximally localized Wannier functions in LaMnO3 within PBE + U, hybrid functionals and partially self-consistent GW: an efficient route to construct ab initio tight-binding parameters for eg perovskites.

    Science.gov (United States)

    Franchini, C; Kováčik, R; Marsman, M; Murthy, S Sathyanarayana; He, J; Ederer, C; Kresse, G

    2012-06-13

    Using the newly developed VASP2WANNIER90 interface we have constructed maximally localized Wannier functions (MLWFs) for the e(g) states of the prototypical Jahn-Teller magnetic perovskite LaMnO(3) at different levels of approximation for the exchange-correlation kernel. These include conventional density functional theory (DFT) with and without the additional on-site Hubbard U term, hybrid DFT and partially self-consistent GW. By suitably mapping the MLWFs onto an effective e(g) tight-binding (TB) Hamiltonian we have computed a complete set of TB parameters which should serve as guidance for more elaborate treatments of correlation effects in effective Hamiltonian-based approaches. The method-dependent changes of the calculated TB parameters and their interplay with the electron-electron (el-el) interaction term are discussed and interpreted. We discuss two alternative model parameterizations: one in which the effects of the el-el interaction are implicitly incorporated in the otherwise 'noninteracting' TB parameters and a second where we include an explicit mean-field el-el interaction term in the TB Hamiltonian. Both models yield a set of tabulated TB parameters which provide the band dispersion in excellent agreement with the underlying ab initio and MLWF bands.

  6. Hybrid nanostructures: synthesis, morphology and functional properties

    International Nuclear Information System (INIS)

    Povolotskaya, A V; Povolotskiy, A V; Manshina, A A

    2015-01-01

    Hybrid nanostructures representing combinations of different materials and possessing properties that are absent in separate components forming the hybrid are discussed. Particular attention is given to hybrid structures containing plasmonic and magnetic nanoparticles, methods of their synthesis and the relationship between the composition, structure and properties. The functional features of the hybrid nanomaterials of various morphology (with core–shell structures, with encapsulated metal nanoparticles and with metal nanoparticles on the surface) are considered. The unique properties of these hybrid materials are demonstrated, which are of interest for solving problems of catalysis and photocatalysis, detecting impurities in various media, in vivo visualization, bioanalysis, as well as for the design of optical labels and multifunctional diagnostic nanoplatforms. The bibliography includes 182 references

  7. Density Functional Theory Embedding for Correlated Wavefunctions

    Science.gov (United States)

    2014-01-01

    PBE, PW91, B3LYP, and PBE0. Unlike the spin-splitting energy, which is highly sensitive to the electronic structure of the Fe atom and is thus impacted ...0.125819 H13 -0.266039 -1.879491 0.392857 H14 -0.114525 -0.651038 1.637376 C15 1.939021 0.764969 0.494120 C16 2.110936 -1.464774 -0.530108 H17 3.144393...0.875560 H11 1.176667 0.837647 0.875568 C12 -1.248215 -0.197709 -0.000001 H13 0.192433 -1.477758 0.870558 H14 0.192433 -1.477754 -0.870565 C15 -1.733584

  8. A highly active hybrid catalyst modified (La0.60Sr0.40)0.95Co0.20Fe0.80O3-δ cathode for proton conducting solid oxide fuel cells

    Science.gov (United States)

    Lei, Libin; Tao, Zetian; Hong, Tao; Wang, Xiaoming; Chen, Fanglin

    2018-06-01

    The sluggish reaction kinetics in the cathode usually leads to considerable cathode polarization resistance, hindering the development of proton conducting solid oxide fuel cells (H-SOFCs) operated at intermediate temperatures (400-650 °C). To address this problem, for the first time, a novel hybrid catalyst consisting of PrNi0.5Mn0.5O3 and PrOx is impregnated in the (La0.60Sr0.40)0.95Co0.20Fe0.80O3-δ (LSCF) cathode of H-SOFCs, resulting in significant enhancement of the cathode reaction kinetics. Single cells with impregnated LSCF cathode and BaZr0.8Y0.2O3 (BZY) electrolyte yield a maximum power density (MPD) of 0.198 W cm-2 at 600 °C, more than doubled of that with blank LSCF cathode (0.083 W cm-2). ECR and EIS studies reveal that the hybrid catalyst can substantially accelerate the oxygen-ion transfer and oxygen dissociation-absorption processes in the cathode, resulting in significantly lower polarization resistance and higher MPD. In addition, the hybrid catalyst possesses good chemical and microstructural stability at 600 °C. Consequently, the single cells with impregnated LSCF cathode show excellent durability. This study shows that the impregnation of this novel hybrid catalyst in the cathode could be a promising approach to improve the performance and stability of H-SOFCs.

  9. Hybrid fixed point in CAT(0 spaces

    Directory of Open Access Journals (Sweden)

    Hemant Kumar Pathak

    2018-02-01

    Full Text Available In this paper, we introduce an ultrapower approach to prove fixed point theorems for $H^{+}$-nonexpansive multi-valued mappings in the setting of CAT(0 spaces and prove several hybrid fixed point results in CAT(0 spaces for families of single-valued nonexpansive or quasinonexpansive mappings and multi-valued upper semicontinuous, almost lower semicontinuous or $H^{+}$-nonexpansive mappings which are weakly commuting. We also establish a result about structure of the set of fixed points of $H^{+}$-quasinonexpansive mapping on a CAT(0 space.

  10. The electronic and optical properties of CH3NH3MoI3 perovskite

    Science.gov (United States)

    Kansara, Shivam; Sonvane, Yogesh; Gupta, Sanjeev K.

    2018-05-01

    In this work, a first-principles theoretical study of hybrid perovskite CH3NH3MoI3 is performed using PBE exchange-correlation approximations in density functional theory. The results of electronic band structure are 0.90 eV (M-point: Direct) and 0.60 eV (R-X point: Indirect), respectively. We have also calculated the dielectric properties such as real, imaginary, extension coefficient (K) and reflectivity (R) properties of hybrid perovskite CH3NH3MoI3. The low-bandgap molecules are used to absorb near-IR range and typically having a bandgap smaller than 1.6 eV. This is particularly attractive in organic photovoltaics (OPV), photodetectors (PDs), and ambipolar field-effect transistors (FETs).

  11. On the universality of the long-/short-range separation in multiconfigurational density-functional theory

    Science.gov (United States)

    Fromager, Emmanuel; Toulouse, Julien; Jensen, Hans Jørgen Aa.

    2007-02-01

    In many cases, the dynamic correlation can be calculated quite accurately and at a fairly low computational cost in Kohn-Sham density-functional theory (KS-DFT), using current standard approximate functionals. However, in general, KS-DFT does not treat static correlation effects (near degeneracy) adequately which, on the other hand, can be described in wave-function theory (WFT), for example, with a multiconfigurational self-consistent field (MCSCF) model. It is therefore of high interest to develop a hybrid model which combines the best of both WFT and DFT approaches. The merge of WFT and DFT can be achieved by splitting the two-electron interaction into long-range and short-range parts. The long-range part is then treated by WFT and the short-range part by DFT. In this work the authors consider the so-called "erf" long-range interaction erf(μr12)/r12, which is based on the standard error function, and where μ is a free parameter which controls the range of the long-/short-range decomposition. In order to formulate a general method, they propose a recipe for the definition of an optimal μopt parameter, which is independent of the approximate short-range functional and the approximate wave function, and they discuss its universality. Calculations on a test set consisting of He, Be, Ne, Mg, H2, N2, and H2O yield μopt≈0.4a.u.. A similar analysis on other types of test systems such as actinide compounds is currently in progress. Using the value of 0.4a.u. for μ, encouraging results are obtained with the hybrid MCSCF-DFT method for the dissociation energies of H2, N2, and H2O, with both short-range local-density approximation and PBE-type functionals.

  12. Local hybrid functionals with orbital-free mixing functions and balanced elimination of self-interaction error

    International Nuclear Information System (INIS)

    Silva, Piotr de; Corminboeuf, Clémence

    2015-01-01

    The recently introduced density overlap regions indicator (DORI) [P. de Silva and C. Corminboeuf, J. Chem. Theory Comput. 10(9), 3745–3756 (2014)] is a density-dependent scalar field revealing regions of high density overlap between shells, atoms, and molecules. In this work, we exploit its properties to construct local hybrid exchange-correlation functionals aiming at balanced reduction of the self-interaction error. We show that DORI can successfully replace the ratio of the von Weizsäcker and exact positive-definite kinetic energy densities, which is commonly used in mixing functions of local hybrids. Additionally, we introduce several semi-empirical parameters to control the local and global admixture of exact exchange. The most promising of our local hybrids clearly outperforms the underlying semi-local functionals as well as their global hybrids

  13. Heats of Formation of Medium-Size Organic Compounds from Contemporary Electronic Structure Methods

    KAUST Repository

    Minenkov, Yury; Wang, Heng; Wang, Zhandong; Sarathy, Mani; Cavallo, Luigi

    2017-01-01

    Computational electronic structure calculations are routinely undertaken to predict thermodynamic properties of the various species. However, the application of highly accurate wave function theory methods, such as the “gold standard” coupled cluster approach including single, double and partly triple excitations in perturbative fashion, CCSD(T), to large molecules is limited due to high computational cost. In this work, the promising domain based local pair natural orbital coupled cluster approach, DLPNO-CCSD(T), has been tested to reproduce 113 accurate formation enthalpies of medium-size molecules (few dozens heavy atoms) important for bio- and combustion chemistry via the reaction based Feller-Peterson-Dixon approach. As for comparison, 8 density functional theory (B3LYP, B3LYP-D3, PBE0, PBE0-D3, M06, M06-2X, ωB97X-D3, and ωB97M-V) and MP2-based (B2PLYP-D3, PWPB95-D3, B2T-PLYP, B2T-PLYP-D, B2GP-PLYP, DSD-PBEP86-D3, SCS-MP2, and OO-SCS-MP2) methods have been tested. The worst performance has been obtained for the standard hybrid DFT functionals, PBE0 (Mean unsigned error (MUE)/ Mean Signed Error (MSE)=9.1/6.0 kcal/mol) and B3LYP (MUE/MSE=13.5/-13.3 kcal/mol). An influence of an empirical dispersion correction term on these functionals performance is not homogenous: B3LYP performance is improved (B3LYP-D3 (MUE/MSE=6.0/0.8 kcal/mol)) meanwhile PBE0 performance is worse (PBE0-D3 (MUE/MSE=14.1/13.6 kcal/mol)). The Minnesota functionals, M06 (MUE/MSE=3.8/-2.0 kcal/mol) and M06-2X (MUE/MSE=3.5/3.0 kcal/mol), and recently developed ωB97X-D3 (MUE/MSE=3.2/0.2 kcal/mol) and ωB97M-V (MUE/MSE=2.2/1.3 kcal/mol) methods provided significantly better formation enthalpies. Enthalpies of similar quality can also be obtained from some double hybrid methods (B2PLYP-D3 (MUE/MSE=4.7/2.0 kcal/mol), PWPB95-D3 (MUE/MSE=4.3/3.2 kcal/mol), B2T-PLYP (MUE/MSE=4.1/-3.0 kcal/mol) and B2T-PLYP-D (MUE/MSE=3.3/1.7 kcal/mol)). The two spin component scaled (SCS) MP2 methods resulted in

  14. Heats of Formation of Medium-Size Organic Compounds from Contemporary Electronic Structure Methods

    KAUST Repository

    Minenkov, Yury

    2017-06-21

    Computational electronic structure calculations are routinely undertaken to predict thermodynamic properties of the various species. However, the application of highly accurate wave function theory methods, such as the “gold standard” coupled cluster approach including single, double and partly triple excitations in perturbative fashion, CCSD(T), to large molecules is limited due to high computational cost. In this work, the promising domain based local pair natural orbital coupled cluster approach, DLPNO-CCSD(T), has been tested to reproduce 113 accurate formation enthalpies of medium-size molecules (few dozens heavy atoms) important for bio- and combustion chemistry via the reaction based Feller-Peterson-Dixon approach. As for comparison, 8 density functional theory (B3LYP, B3LYP-D3, PBE0, PBE0-D3, M06, M06-2X, ωB97X-D3, and ωB97M-V) and MP2-based (B2PLYP-D3, PWPB95-D3, B2T-PLYP, B2T-PLYP-D, B2GP-PLYP, DSD-PBEP86-D3, SCS-MP2, and OO-SCS-MP2) methods have been tested. The worst performance has been obtained for the standard hybrid DFT functionals, PBE0 (Mean unsigned error (MUE)/ Mean Signed Error (MSE)=9.1/6.0 kcal/mol) and B3LYP (MUE/MSE=13.5/-13.3 kcal/mol). An influence of an empirical dispersion correction term on these functionals performance is not homogenous: B3LYP performance is improved (B3LYP-D3 (MUE/MSE=6.0/0.8 kcal/mol)) meanwhile PBE0 performance is worse (PBE0-D3 (MUE/MSE=14.1/13.6 kcal/mol)). The Minnesota functionals, M06 (MUE/MSE=3.8/-2.0 kcal/mol) and M06-2X (MUE/MSE=3.5/3.0 kcal/mol), and recently developed ωB97X-D3 (MUE/MSE=3.2/0.2 kcal/mol) and ωB97M-V (MUE/MSE=2.2/1.3 kcal/mol) methods provided significantly better formation enthalpies. Enthalpies of similar quality can also be obtained from some double hybrid methods (B2PLYP-D3 (MUE/MSE=4.7/2.0 kcal/mol), PWPB95-D3 (MUE/MSE=4.3/3.2 kcal/mol), B2T-PLYP (MUE/MSE=4.1/-3.0 kcal/mol) and B2T-PLYP-D (MUE/MSE=3.3/1.7 kcal/mol)). The two spin component scaled (SCS) MP2 methods resulted in

  15. Theoretical Prediction of an Antimony-Silicon Monolayer (penta-Sb2Si): Band Gap Engineering by Strain Effect

    Science.gov (United States)

    Morshedi, Hosein; Naseri, Mosayeb; Hantehzadeh, Mohammad Reza; Elahi, Seyed Mohammad

    2018-04-01

    In this paper, using a first principles calculation, a two-dimensional structure of silicon-antimony named penta-Sb2Si is predicted. The structural, kinetic, and thermal stabilities of the predicted monolayer are confirmed by the cohesive energy calculation, phonon dispersion analysis, and first principles molecular dynamic simulation, respectively. The electronic properties investigation shows that the pentagonal Sb2Si monolayer is a semiconductor with an indirect band gap of about 1.53 eV (2.1 eV) from GGA-PBE (PBE0 hybrid functional) calculations which can be effectively engineered by employing external biaxial compressive and tensile strain. Furthermore, the optical characteristics calculation indicates that the predicted monolayer has considerable optical absorption and reflectivity in the ultraviolet region. The results suggest that a Sb2Si monolayer has very good potential applications in new nano-optoelectronic devices.

  16. White-emissive tandem-type hybrid organic/polymer diodes with (0.33, 0.33) chromaticity coordinates.

    Science.gov (United States)

    Guo, Tzung-Fang; Wen, Ten-Chin; Huang, Yi-Shun; Lin, Ming-Wei; Tsou, Chuan-Cheng; Chung, Chia-Tin

    2009-11-09

    This study reports fabrication of white-emissive, tandem-type, hybrid organic/polymer light-emitting diodes (O/PLED). The tandem devices are made by stacking a blue-emissive OLED on a yellow-emissive phenyl-substituted poly(para-phenylene vinylene) copolymer-based PLED and applying an organic oxide/Al/molybdenum oxide (MoO(3)) complex structure as a connecting structure or charge-generation layer (CGL). The organic oxide/Al/MoO(3) CGL functions as an effective junction interface for the transport and injection of opposite charge carriers through the stacked configuration. The electroluminescence (EL) spectra of the tandem-type devices can be tuned by varying the intensity of the emission in each emissive component to yield the visible-range spectra from 400 to 750 nm, with Commission Internationale de l'Eclairage chromaticity coordinates of (0.33, 0.33) and a high color rendering capacity as used for illumination. The EL spectra also exhibit good color stability under various bias conditions. The tandem-type device of emission with chromaticity coordinates, (0.30, 0.31), has maximum brightness and luminous efficiency over 25,000 cd/m(2) and approximately 4.2 cd/A, respectively.

  17. Characterizing the potential energy surface of the water dimer with DFT: failures of some popular functionals for hydrogen bonding.

    Science.gov (United States)

    Anderson, Julie A; Tschumper, Gregory S

    2006-06-08

    Ten stationary points on the water dimer potential energy surface have been examined with ten density functional methods (X3LYP, B3LYP, B971, B98, MPWLYP, PBE1PBE, PBE, MPW1K, B3P86, and BHandHLYP). Geometry optimizations and vibrational frequency calculations were carried out with the TZ2P(f,d)+dif basis set. All ten of the density functionals correctly describe the relative energies of the ten stationary points. However, correctly describing the curvature of the potential energy surface is far more difficult. Only one functional (BHandHLYP) reproduces the number of imaginary frequencies from CCSD(T) calculations. The other nine density functionals fail to correctly characterize the nature of at least one of the ten (H(2)O)(2) stationary points studied here.

  18. Investigation of iron spin crossover pressure in Fe-bearing MgO using hybrid functional

    Science.gov (United States)

    Cheng, Ya; Wang, Xianlong; Zhang, Jie; Yang, Kaishuai; Zhang, Chuanguo; Zeng, Zhi; Lin, Haiqin

    2018-04-01

    Pressure-induced spin crossover behaviors of Fe-bearing MgO were widely investigated by using an LDA  +  U functional for describing the strongly correlated Fe–O bonding. Moreover, the simulated spin crossover pressures depend on the applied U values, which are sensitive to environments and parameters. In this work, the spin crossover pressures of (Mg1‑x ,Fe x )O are investigated by using the hybrid functional with a uniform parameter. Our results indicate that the spin crossover pressures increase with increasing iron concentration. For example, the spin crossover pressure of (Mg0.03125,Fe0.96875)O and FeO was 56 GPa and 127 GPa, respectively. The calculated crossover pressures agreed well with the experimental observations. Therefore, the hybrid functional should be an effective method for describing the pressure-induced spin crossover behaviors in transition metal oxides.

  19. Accurate Valence Ionization Energies from Kohn-Sham Eigenvalues with the Help of Potential Adjustors.

    Science.gov (United States)

    Thierbach, Adrian; Neiss, Christian; Gallandi, Lukas; Marom, Noa; Körzdörfer, Thomas; Görling, Andreas

    2017-10-10

    An accurate yet computationally very efficient and formally well justified approach to calculate molecular ionization potentials is presented and tested. The first as well as higher ionization potentials are obtained as the negatives of the Kohn-Sham eigenvalues of the neutral molecule after adjusting the eigenvalues by a recently [ Görling Phys. Rev. B 2015 , 91 , 245120 ] introduced potential adjustor for exchange-correlation potentials. Technically the method is very simple. Besides a Kohn-Sham calculation of the neutral molecule, only a second Kohn-Sham calculation of the cation is required. The eigenvalue spectrum of the neutral molecule is shifted such that the negative of the eigenvalue of the highest occupied molecular orbital equals the energy difference of the total electronic energies of the cation minus the neutral molecule. For the first ionization potential this simply amounts to a ΔSCF calculation. Then, the higher ionization potentials are obtained as the negatives of the correspondingly shifted Kohn-Sham eigenvalues. Importantly, this shift of the Kohn-Sham eigenvalue spectrum is not just ad hoc. In fact, it is formally necessary for the physically correct energetic adjustment of the eigenvalue spectrum as it results from ensemble density-functional theory. An analogous approach for electron affinities is equally well obtained and justified. To illustrate the practical benefits of the approach, we calculate the valence ionization energies of test sets of small- and medium-sized molecules and photoelectron spectra of medium-sized electron acceptor molecules using a typical semilocal (PBE) and two typical global hybrid functionals (B3LYP and PBE0). The potential adjusted B3LYP and PBE0 eigenvalues yield valence ionization potentials that are in very good agreement with experimental values, reaching an accuracy that is as good as the best G 0 W 0 methods, however, at much lower computational costs. The potential adjusted PBE eigenvalues result in

  20. Automation methodologies and large-scale validation for G W : Towards high-throughput G W calculations

    Science.gov (United States)

    van Setten, M. J.; Giantomassi, M.; Gonze, X.; Rignanese, G.-M.; Hautier, G.

    2017-10-01

    The search for new materials based on computational screening relies on methods that accurately predict, in an automatic manner, total energy, atomic-scale geometries, and other fundamental characteristics of materials. Many technologically important material properties directly stem from the electronic structure of a material, but the usual workhorse for total energies, namely density-functional theory, is plagued by fundamental shortcomings and errors from approximate exchange-correlation functionals in its prediction of the electronic structure. At variance, the G W method is currently the state-of-the-art ab initio approach for accurate electronic structure. It is mostly used to perturbatively correct density-functional theory results, but is, however, computationally demanding and also requires expert knowledge to give accurate results. Accordingly, it is not presently used in high-throughput screening: fully automatized algorithms for setting up the calculations and determining convergence are lacking. In this paper, we develop such a method and, as a first application, use it to validate the accuracy of G0W0 using the PBE starting point and the Godby-Needs plasmon-pole model (G0W0GN @PBE) on a set of about 80 solids. The results of the automatic convergence study utilized provide valuable insights. Indeed, we find correlations between computational parameters that can be used to further improve the automatization of G W calculations. Moreover, we find that G0W0GN @PBE shows a correlation between the PBE and the G0W0GN @PBE gaps that is much stronger than that between G W and experimental gaps. However, the G0W0GN @PBE gaps still describe the experimental gaps more accurately than a linear model based on the PBE gaps. With this paper, we hence show that G W can be made automatic and is more accurate than using an empirical correction of the PBE gap, but that, for accurate predictive results for a broad class of materials, an improved starting point or some

  1. Development on hybrid evaluated nuclear data library HENDL1.0/MG/MC

    International Nuclear Information System (INIS)

    Xu Dezheng; Gao Chunjing; Zheng Shanliang; Liu Haibo; Zhu Xiaoxiang; Li Jingjing; Wu Yican

    2004-01-01

    A Hybrid Evaluated Nuclear Data Library (HENDL) named as HENDL1.0 has been developed by Fusion Design Study (FDS) team of Institute of Plasma Physics, Academia Sinica (ASIPP) to take into account the requirements in design and research relevant to fusion, fission and fusion-fission sub-critical hybrid reactor. HENDLI1.0 contains one basic evaluated sub-library naming HENDL1.0/E and to processed working sub-libraries naming HENDL1.0/MG and HENDL1.0/MC, respectively. Through carefully comparing, distinguishing and choosing, HENDL1.0/E integrated basic evaluated neutron data files of 213 nuclides from the several main data libraries for evaluated neutron reaction cross sections including ENDF/B-VI (USA), JEF-2.2 (OECD/NEA, Europe), JENDL-3.2 (Japan), CENDL-2 (China), BROND-2 (Russia) and FENDL-2 (IAEA/NDS, ITER program). Based on this, 175-group neutron and 42-group photon neutron-photon coupled multi-group working library HENDL1.0/MG used for discrete ordinate Sn method transport calculation (such as ANISN code) and a compact ENDF form (ACE), continuous energy structure (pointwise) neutron cross section library HENDL1.0/MC for Monte Carlo method transport simulation (as MCMP code) can be attainable with the current group constants processing system NJOY and transport cross section preparation code TRANSX referring to the Vitamin-J energy group structure. In addition, two special bases i.e. transmutation (burnup) library BURNUP. DAT and response function library RESPONSE.DAT, have been also made for fuel cycle calculation and reactivity analyses of nuclear reactor. The relevant sample testing, benchmark checking and primary confirmation are also carried out to assess the validity of multi-purpose data library HENDL1.0. (authors)

  2. A general range-separated double-hybrid density-functional theory.

    Science.gov (United States)

    Kalai, Cairedine; Toulouse, Julien

    2018-04-28

    A range-separated double-hybrid (RSDH) scheme which generalizes the usual range-separated hybrids and double hybrids is developed. This scheme consistently uses a two-parameter Coulomb-attenuating-method (CAM)-like decomposition of the electron-electron interaction for both exchange and correlation in order to combine Hartree-Fock exchange and second-order Møller-Plesset (MP2) correlation with a density functional. The RSDH scheme relies on an exact theory which is presented in some detail. Several semi-local approximations are developed for the short-range exchange-correlation density functional involved in this scheme. After finding optimal values for the two parameters of the CAM-like decomposition, the RSDH scheme is shown to have a relatively small basis dependence and to provide atomization energies, reaction barrier heights, and weak intermolecular interactions globally more accurate or comparable to range-separated MP2 or standard MP2. The RSDH scheme represents a new family of double hybrids with minimal empiricism which could be useful for general chemical applications.

  3. Assessment of density functional theory for bonds formed between rare gases and open-shell atoms: a computational study of small molecules containing He, Ar, Kr and Xe.

    Science.gov (United States)

    Bertolus, Marjorie; Major, Mohamed; Brenner, Valérie

    2012-01-14

    The validity of the description of the DFT approximations currently implemented in plane wave DFT codes (LDA, GGA, meta-GGA, hybrid, GGA + empirical dispersion correction) for interactions between rare gases and open-shell atoms which form materials is poorly known. We have performed a first assessment of the accuracy of these functionals for the description of the bonds formed by helium, argon, krypton and xenon with various open-shell atoms. This evaluation has been done on model molecular systems for which precise experimental data are available and reference post-Hartree-Fock calculations (CCSD(T) using large basis sets) are feasible. The results show that when the rare gas atom shares density with the neighbouring atoms, the GGA functionals yield good geometries and qualitatively correct binding energies, even if these are quite significantly overestimated. The use of hybrid functionals enables us to obtain good geometries and satisfactory binding energies. For compounds in which the rare gas atom forms weak dispersive-like bonding, the accuracy yielded by the various functionals is not as good. No functional gives satisfactory binding energies for all the compounds investigated. Several GGA and hybrid functionals yield correct geometries, even if some isomers are not obtained. One GGA functional (PBE) yields qualitatively correct results for the compounds of the three rare gases and several hybrid functionals give satisfactory energies for He compounds. The addition of an empirical dispersive correction improves the results on association compounds, but several isomers are not found.

  4. Assessment of density functional theory for bonds formed between rare gases and open-shell atoms: a computational study of small molecules containing He, Ar, Kr and Xe

    International Nuclear Information System (INIS)

    Bertolus, Marjorie; Major, Mohamed; Brenner, Valerie

    2012-01-01

    The validity of the description of the DFT approximations currently implemented in plane wave DFT codes (LDA, GGA, meta-GGA, hybrid, GGA + empirical dispersion correction) for interactions between rare gases and open-shell atoms which form materials is poorly known. We have performed a first assessment of the accuracy of these functionals for the description of the bonds formed by helium, argon, krypton and xenon with various open-shell atoms. This evaluation has been done on model molecular systems for which precise experimental data are available and reference post-Hartree-Fock calculations (CCSD(T) using large basis sets) are feasible. The results show that when the rare gas atom shares density with the neighbouring atoms, the GGA functionals yield good geometries and qualitatively correct binding energies, even if these are quite significantly overestimated. The use of hybrid functionals enables us to obtain good geometries and satisfactory binding energies. For compounds in which the rare gas atom forms weak dispersive-like bonding, the accuracy yielded by the various functionals is not as good. No functional gives satisfactory binding energies for all the compounds investigated. Several GGA and hybrid functionals yield correct geometries, even if some isomers are not obtained. One GGA functional (PBE) yields qualitatively correct results for the compounds of the three rare gases and several hybrid functionals give satisfactory energies for He compounds. The addition of an empirical dispersive correction improves the results on association compounds, but several isomers are not found. (authors)

  5. Effects of density functionals and dispersion interactions on geometries, bond energies and harmonic frequencies of Etbnd UX3 (E = N, P, CH; X = H, F, Cl)

    Science.gov (United States)

    Pandey, Krishna Kumar; Patidar, Pankaj; Patidar, Sunil Kumar; Vishwakarma, Ravi

    2014-12-01

    Quantum-chemical calculations have been performed to evaluate the geometries, bonding nature and harmonic frequencies of the compounds [Etbnd UX3] at DFT, DFT-D3, DFT-D3(BJ) and DFT-dDSc levels using different density functionals BP86, BLYP, PBE, revPBE, PW91, TPSS and M06-L. The stretching frequency of Utbnd N bond in [Ntbnd UF3] calculated with DFT/BLYP closely resembles with the experimental value. The performance of different density functionals for accurate Utbnd N vibrational frequencies follows the order BLYP > revPBE > BP86 > PW91 > TPSS > PBE > M06-L. The BLYP functional gives accurate value of the Utbnd E bond distances. The uranium atom in the studied compounds [Etbnd UX3] is positively charged. Upon going from [Etbnd UF3] to [Etbnd UCl3], the partial Hirshfeld charge on uranium atom decreases because of the lower electronegativity of chlorine compared to flourine. The Gopinathan-Jug bond order for Utbnd E bonds ranges from 2.90 to 3.29. The Utbnd E bond dissociation energies vary with different density functionals as M06-L < TPSS < BLYP < revPBE < BP86 < PBE ≈ PW91. The orbital interactions ΔEorb, in all studied compounds [Etbnd UX3] are larger than the electrostatic interaction ΔEelstat, which means the Utbnd N bonds in these compound have greater degree of covalent character (in the range 63.8-77.2%). The Usbnd E σ-bonding interaction is the dominant bonding interaction in the nitride and methylidyne complexes while it is weaker in [Ptbnd UX3]. The dispersion energy contributions to the total bond dissociation energies are rather small. Compared to the Grimme's D3(BJ) corrections, the Corminboeuf's dispersion corrections are larger with metaGGA functionals (TPSS, M06-L) while smaller with GGA functionals.

  6. Development and benchmark analysis of the hybrid evaluated nuclear data library HENDL1.0

    International Nuclear Information System (INIS)

    Xu Dezheng; Wu Yican; Gao Chunjing; Zheng Shanliang; Li Jingjing; Zhu Xiaoxiang; Liu Haibo

    2004-01-01

    To meet the requirements of fusion-fission sub-critical hybrid reactor design and the other related studies, the evaluate nuclear data library named HENDL1.0/E has been constituted based on the several main national evaluated data libraries. The relevant working libraries including transport sub-libraries HENDL1.0/MG in groupwise form, HENDL1.0/MC in pointwise form, and the burnup sub-library HENDL1.0/BU and response function sub-library HENDL1.0/RF are generated using the nuclear data processing codes NJOY97 and TRANSX2. The simulating calculation and comparative analysis are carried out against a series of existing benchmark test experiments with popular neutron transport codes, in order to validate the correctness and availability of the HENDL1.0. (authors)

  7. The electronic spectrum of CUONg(4) (Ng = Ne, Ar, Kr, Xe): New insights in the interaction of the CUO molecule with noble gas matrices

    NARCIS (Netherlands)

    Tecmer, P.; van Lingen, H.; Gomes, A.S.P.; Visscher, L.

    2012-01-01

    The electronic spectrum of the CUO molecule was investigated with the IHFSCC-SD (intermediate Hamiltonian Fock-space coupled cluster with singles and doubles) method and with TD-DFT (time-dependent density functional theory) employing the PBE and PBE0 exchange-correlation functionals. The importance

  8. Hydrogels from Biopolymer Hybrid for Biomedical, Food, and Functional Food Applications

    Directory of Open Access Journals (Sweden)

    Robert C. Spiro

    2012-04-01

    Full Text Available Hybrid hydrogels from biopolymers have been applied for various indications across a wide range of biomedical, pharmaceutical, and functional food industries. In particular, hybrid hydrogels synthesized from two biopolymers have attracted increasing attention. The inclusion of a second biopolymer strengthens the stability of resultant hydrogels and enriches its functionalities by bringing in new functional groups or optimizing the micro-environmental conditions for certain biological and biochemical processes. This article presents approaches that have been used by our groups to synthesize biopolymer hybrid hydrogels for effective uses for immunotherapy, tissue regeneration, food and functional food applications. The research has achieved some challenging results, such as stabilizing physical structure, increasing mucoadhesiveness, and the creation of an artificial extracellular matrix to aid in guiding tissue differentiation.

  9. Theoretical study of the electronic and magnetic properties of β-TeVO4

    Science.gov (United States)

    Saul, Andres; Radtke, Guillaume

    2014-03-01

    The β phase of this compound can be described by zigzag chains formed by VO5 distorted square pyramids sharing corners. This oxide, with V4+ ions as magnetic centers, can be thus seen as a realization of a quasi-one-dimensional Heisenberg S=1/2 Hamiltonian. The corner-sharing of the VO5 pyramids could lead to the prediction of AFM nearest neighbor interactions mediated by a weak super-exchange mechanism opening the possibility of complex magnetic properties due to competing next nearest-neighbors or inter-chain interactions. In this work we have studied its electronic and magnetic properties using density functional calculations. In particular, we evaluated the magnetic couplings on the basis of broken-symmetry formalism. We have performed extensive calculations comparing the results of the standard GGA (PBE) functional to the hybrid PBE0 functional and two different GGA+U implementations (SIC and AMF). The overall picture that arises from our calculations is of a frustrated AFM system with small FM nearest neigbors interactions but larger AFM nearest neighbors couplings. We discuss our results in the framework of the Kugel-Khomskii model using a projection of the electronic structure in localized Wannier functions.

  10. Hybride magnetic nanostructure based on amino acids functionalized polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Alexandrina, E-mail: alexandrina.nan@itim-cj.ro; Bunge, Alexander; Turcu, Rodica [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca (Romania)

    2015-12-23

    Conducting polypyrrole is especially promising for many commercial applications because of its unique optical, electric, thermal and mechanical properties. We report the synthesis and characterization of novel pyrrole functionalized monomers and core-shell hybrid nanostructures, consisting of a conjugated polymer layer (amino acids functionalized pyrrole copolymers) and a magnetic nanoparticle core. For functionalization of the pyrrole monomer we used several amino acids: tryptophan, leucine, phenylalanine, serine and tyrosine. These amino acids were linked via different types of hydrophobic linkers to the nitrogen atom of the pyrrole monomer. The magnetic core-shell hybrid nanostructures are characterized by various methods such as FTIR spectroscopy, transmission electron microscopy (TEM) and magnetic measurements.

  11. Benchmarking triplet-triplet annihilation photon upconversion schemes.

    Science.gov (United States)

    Gertsen, Anders S; Koerstz, Mads; Mikkelsen, Kurt V

    2018-05-07

    Photon upconversion facilitated by triplet-triplet annihilation in molecular systems is a promising path toward utilization of sub bandgap photons in photovoltaic devices. Prior to the challenging synthesis of new molecules, quantum chemical computations can aid the design process and provide suggestions for new and optimal systems. Here, we benchmark time-dependent density functional methods by their ability to describe relevant photophysical quantities of a range of different types of sensitizer/annihilator pairs to provide guidelines for future computational studies of potential new pairs. Using meta-GGA, hybrid, and range-separated hybrid functionals, we find that the hybrid functionals B3LYP and PBE0 (incorporating low to medium fractions of exact exchange of 20% and 25%, respectively) describe singlet absorptions the best, while triplet energetics are best described by the meta-GGA functionals M06-L and M11-L (incorporating no exact exchange), respectively. Furthermore, we find that the Tamm-Dancoff approximation of time-dependent density functional theory in general does not improve the description of neither singlet nor triplet energies of sensitizer/annihilator pairs.

  12. Characteristic of Hybrid Cellulose-Amino Functionalized POSS-Silica Nanocomposite and Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    Sivalingam Ramesh

    2015-01-01

    Full Text Available Recently, cellulose has much attention as an emerging renewable nanomaterial which holds promising properties having unique piezoelectricity, insulating, and biodegradable nature for various applications. Also, the modified properties of cellulose by appropriate chemical modifications in various functional groups with outstanding properties or significantly improved physical, chemical, biological, and electronic properties will widen the way for it to be utilized in different usages. Therefore, in this paper, cellulose-functionalized polyhedral oligomeric silsesquioxanes (POSS based materials were considered an important class of high-performance hybrid nanocomposite materials. To functionalize the regenerated cellulose, amino functionalized POSS material was synthesized via sol-gel covalent crosslinking process in presence of amino coupling agent. In this reaction, tetraethoxsilane (TEOS and γ-aminopropyltriethoxy silane (γ-APTES as coupling agent for metal precursors were selected. The chemical structure of cellulose-amine functionalized bonding and covalent crosslinking hybrids was confirmed by FTIR and 1H NMR spectral analysis. From the TEM results, well-dispersed hybrid cellulose-functionalized POSS-silica composites are observed. The resulting cellulose-POSS-silica hybrid nanocomposites materials provided significantly improved the optical transparency, and thermal and morphological properties to compare the cellulose-silica hybrid materials. Further, antimicrobial test against pathogenic bacteria was carried out.

  13. An efficient method for hybrid density functional calculation with spin-orbit coupling

    Science.gov (United States)

    Wang, Maoyuan; Liu, Gui-Bin; Guo, Hong; Yao, Yugui

    2018-03-01

    In first-principles calculations, hybrid functional is often used to improve accuracy from local exchange correlation functionals. A drawback is that evaluating the hybrid functional needs significantly more computing effort. When spin-orbit coupling (SOC) is taken into account, the non-collinear spin structure increases computing effort by at least eight times. As a result, hybrid functional calculations with SOC are intractable in most cases. In this paper, we present an approximate solution to this problem by developing an efficient method based on a mixed linear combination of atomic orbital (LCAO) scheme. We demonstrate the power of this method using several examples and we show that the results compare very well with those of direct hybrid functional calculations with SOC, yet the method only requires a computing effort similar to that without SOC. The presented technique provides a good balance between computing efficiency and accuracy, and it can be extended to magnetic materials.

  14. Hydrodynamic analysis of the LMFBR prompt burst excursion (PBE) experiment

    International Nuclear Information System (INIS)

    Young, M.F.

    1977-01-01

    A series of in-pile experiments has been conducted at Sandia Laboratories to provide information on pressure levels and conversion of thermal energy into mechanical work in LMFBR cores during hypothetical, superprompt-critical excursions. Pressures generated in these experiments are recorded by a pressure transducer located at the top and bottom of a sodium channel surrounding a single, fresh UO 2 fuel pin. Work energy conversion is measured by a linear motion transducer connected to a piston at the top of the sodium column. Since the pressure transducers are located fairly far from the location of pin failure, it becomes necessary to determine the effect of channel geometry and piston motion on the observed pressure data. A two-dimensional, hydrodynamic analysis of pressure pulse propagation in the fuel pin-coolant channel geometry was therefore performed using the CSQII computer code. The initial series of PBE experiments consists of single, fresh UO 2 pins surrounded by a sodium-filled or dry-coolant channel contained in a closed test capsule. The capsule is subjected to a maximum pulse in the Annular Core Pulse Reactor (ACPR) resulting in an energy deposition of from 2350 to 2900 J/g (14 and 20 percent enriched pins). The pulse width at half maximum (PWHM) is about 5 ms

  15. Accurate simulation of geometry, singlet-singlet and triplet-singlet excitation of cyclometalated iridium(III) complex.

    Science.gov (United States)

    Wang, Jian; Bai, Fu-Quan; Xia, Bao-Hui; Zhang, Hong-Xing; Cui, Tian

    2014-03-01

    In the current contribution, we present a critical study of the theoretical protocol used for the determination of the electronic spectra properties of luminescent cyclometalated iridium(III) complex, [Ir(III)(ppy)₂H₂dcbpy]⁺ (where, ppy = 2-phenylpyridine, H₂dcbpy = 2,2'-bipyridine-4,4'-dicarboxylic acid), considered as a representative example of the various problems related to the prediction of electronic spectra of transition metal complex. The choice of the exchange-correlation functional is crucial for the validity of the conclusions that would be drawn from the numerical results. The influence of the exchange-correlation on geometry parameter and absorption/emission band, the role of solvent effects on time-dependent density function theory (TD-DFT) calculations, as well as the importance of the chosen proper procedure to optimize triplet excited geometry, have been thus examined in detail. From the obtained results, some general conclusions and guidelines are presented: i) PBE0 functional is the most accurate in prediction of ground state geometry; ii) the well-established B3LYP, B3P86, PBE0, and X3LYP have similar accuracy in calculation of absorption spectrum; and iii) the hybrid approach TD-DFT//CIS gives out excellent agreement in the evaluation of triplet excitation energy.

  16. A Hybrid Algorithm for Optimizing Multi- Modal Functions

    Institute of Scientific and Technical Information of China (English)

    Li Qinghua; Yang Shida; Ruan Youlin

    2006-01-01

    A new genetic algorithm is presented based on the musical performance. The novelty of this algorithm is that a new genetic algorithm, mimicking the musical process of searching for a perfect state of harmony, which increases the robustness of it greatly and gives a new meaning of it in the meantime, has been developed. Combining the advantages of the new genetic algorithm, simplex algorithm and tabu search, a hybrid algorithm is proposed. In order to verify the effectiveness of the hybrid algorithm, it is applied to solving some typical numerical function optimization problems which are poorly solved by traditional genetic algorithms. The experimental results show that the hybrid algorithm is fast and reliable.

  17. Comparison of some dispersion-corrected and traditional functionals as applied to peptides and conformations of cyclohexane derivatives

    OpenAIRE

    Marianski, Mateusz; Asensio, Amparo; Dannenberg, J. J.

    2012-01-01

    We compare the energetic and structural properties of fully optimized α-helical and antiparallel β-sheet polyalanines and the energetic differences between axial and equatorial conformations of three cyclohexane derivatives (methyl, fluoro, and chloro) as calculated using several functionals designed to treat dispersion (B97-D, ωB97x-D, M06, M06L, and M06-2X) with other traditional functionals not specifically parametrized to treat dispersion (B3LYP, X3LYP, and PBE1PBE) and with experimental ...

  18. Hybrid local piezoelectric and conductive functions for high performance airborne sound absorption

    Science.gov (United States)

    Rahimabady, Mojtaba; Statharas, Eleftherios Christos; Yao, Kui; Sharifzadeh Mirshekarloo, Meysam; Chen, Shuting; Tay, Francis Eng Hock

    2017-12-01

    A concept of hybrid local piezoelectric and electrical conductive functions for improving airborne sound absorption is proposed and demonstrated in composite foam made of porous polar polyvinylidene fluoride (PVDF) mixed with conductive single-walled carbon nanotube (SWCNT). According to our hybrid material function design, the local piezoelectric effect in the PVDF matrix with the polar structure and the electrical resistive loss of SWCNT enhanced sound energy conversion to electrical energy and subsequently to thermal energy, respectively, in addition to the other known sound absorption mechanisms in a porous material. It is found that the overall energy conversion and hence the sound absorption performance are maximized when the concentration of the SWCNT is around the conductivity percolation threshold. For the optimal composition of PVDF/5 wt. % SWCNT, a sound reduction coefficient of larger than 0.58 has been obtained, with a high sound absorption coefficient higher than 50% at 600 Hz, showing their great values for passive noise mitigation even at a low frequency.

  19. Non-covalently functionalized carbon nanostructures for synthesizing carbon-based hybrid nanomaterials.

    Science.gov (United States)

    Li, Haiqing; Song, Sing I; Song, Ga Young; Kim, Il

    2014-02-01

    Carbon nanostructures (CNSs) such as carbon nanotubes, graphene sheets, and nanodiamonds provide an important type of substrate for constructing a variety of hybrid nanomaterials. However, their intrinsic chemistry-inert surfaces make it indispensable to pre-functionalize them prior to immobilizing additional components onto their surfaces. Currently developed strategies for functionalizing CNSs include covalent and non-covalent approaches. Conventional covalent treatments often damage the structure integrity of carbon surfaces and adversely affect their physical properties. In contrast, the non-covalent approach offers a non-destructive way to modify CNSs with desired functional surfaces, while reserving their intrinsic properties. Thus far, a number of surface modifiers including aromatic compounds, small-molecular surfactants, amphiphilic polymers, and biomacromolecules have been developed to non-covalently functionalize CNS surfaces. Mediated by these surface modifiers, various functional components such as organic species and inorganic nanoparticles were further decorated onto their surfaces, resulting in versatile carbon-based hybrid nanomaterials with broad applications in chemical engineering and biomedical areas. In this review, the recent advances in the generation of such hybrid nanostructures based on non-covalently functionalized CNSs will be reviewed.

  20. Affordable and accurate large-scale hybrid-functional calculations on GPU-accelerated supercomputers

    Science.gov (United States)

    Ratcliff, Laura E.; Degomme, A.; Flores-Livas, José A.; Goedecker, Stefan; Genovese, Luigi

    2018-03-01

    Performing high accuracy hybrid functional calculations for condensed matter systems containing a large number of atoms is at present computationally very demanding or even out of reach if high quality basis sets are used. We present a highly optimized multiple graphics processing unit implementation of the exact exchange operator which allows one to perform fast hybrid functional density-functional theory (DFT) calculations with systematic basis sets without additional approximations for up to a thousand atoms. With this method hybrid DFT calculations of high quality become accessible on state-of-the-art supercomputers within a time-to-solution that is of the same order of magnitude as traditional semilocal-GGA functionals. The method is implemented in a portable open-source library.

  1. Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

    KAUST Repository

    Fonari, A.; Corbin, N. S.; Vermeulen, D.; Goetz, K. P.; Jurchescu, O. D.; McNeil, L. E.; Bredas, Jean-Luc; Coropceanu, V.

    2015-01-01

    We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as the electron donor and PMDA as the electron acceptor, is taken as a representative system for which experimental non-resonance Raman spectra are also reported. We first investigate the impact that the amount of nonlocal Hartree-Fock exchange (HFE) included in a hybrid density functional has on the geometry, normal vibrational modes, electronic coupling, and electron-vibrational (phonon) couplings. The comparison between experimental and theoreticalRaman spectra indicates that the results based on the αPBE functional with 25%-35% HFE are in better agreement with the experimental results compared to those obtained with the pure PBE functional. Then, taking αPBE with 25% HFE, we assign the vibrational modes and examine their contributions to the relaxation energy related to the nonlocal electron-vibration interactions. The results show that the largest contribution (about 90%) is due to electron interactions with low-frequency vibrational modes. The relaxation energy in anthracene-PMDA is found to be about five times smaller than the electronic coupling.

  2. Vibrational properties of organic donor-acceptor molecular crystals: Anthracene-pyromellitic-dianhydride (PMDA) as a case study

    KAUST Repository

    Fonari, A.

    2015-12-10

    We establish a reliable quantum-mechanical approach to evaluate the vibrational properties of donor-acceptor molecular crystals. The anthracene-PMDA (PMDA = pyromellitic dianhydride) crystal, where anthracene acts as the electron donor and PMDA as the electron acceptor, is taken as a representative system for which experimental non-resonance Raman spectra are also reported. We first investigate the impact that the amount of nonlocal Hartree-Fock exchange (HFE) included in a hybrid density functional has on the geometry, normal vibrational modes, electronic coupling, and electron-vibrational (phonon) couplings. The comparison between experimental and theoreticalRaman spectra indicates that the results based on the αPBE functional with 25%-35% HFE are in better agreement with the experimental results compared to those obtained with the pure PBE functional. Then, taking αPBE with 25% HFE, we assign the vibrational modes and examine their contributions to the relaxation energy related to the nonlocal electron-vibration interactions. The results show that the largest contribution (about 90%) is due to electron interactions with low-frequency vibrational modes. The relaxation energy in anthracene-PMDA is found to be about five times smaller than the electronic coupling.

  3. Hybridization State Detection of DNA-Functionalized Gold Nanoparticles Using Hyperspectral Imaging

    Directory of Open Access Journals (Sweden)

    Richard C. Murdock

    2017-01-01

    Full Text Available Hyperspectral imaging has the unique ability of capturing spectral data for multiple wavelengths at each pixel in an image. This gives the ability to distinguish, with certainty, different nanomaterials and/or distinguish nanomaterials from biological materials. In this study, 4 nm and 13 nm gold nanoparticles (Au NPs were synthesized, functionalized with complimentary oligonucleotides, and hybridized to form large networks of NPs. Scattering spectra were collected from each sample (unfunctionalized, functionalized, and hybridized and evaluated. The spectra showed unique peaks for each size of Au NP sample and also exhibited narrowing and intensifying of the spectra as the NPs were functionalized and then subsequently hybridized. These spectra are different from normal aggregation effects where the LSPR and reflected spectrum broaden and are red-shifted. Rather, this appears to be dependent on the ability to control the interparticle distance through oligonucleotide length, which is also investigated through the incorporation of a poly-A spacer. Also, hybridized Au NPs were exposed to cells with no adverse effects and retained their unique spectral signatures. With the ability to distinguish between hybridization states at nearly individual NP levels, this could provide a new method of tracking the intracellular actions of nanomaterials as well as extracellular biosensing applications.

  4. Hybrid functional calculation of electronic and phonon structure of BaSnO3

    International Nuclear Information System (INIS)

    Kim, Bog G.; Jo, J.Y.; Cheong, S.W.

    2013-01-01

    Barium stannate, BaSnO 3 (BSO), with a cubic perovskite structure, has been highlighted as a promising host material for the next generation transparent oxide electrodes. This study examined theoretically the electronic structure and phonon structure of BSO using hybrid density functional theory based on the HSE06 functional. The electronic structure results of BSO were corrected by extending the phonon calculations based on the hybrid density functional. The fundamental thermal properties were also predicted based on a hybrid functional calculation. Overall, a detailed understanding of the electronic structure, phonon modes and phonon dispersion of BSO will provide a theoretical starting-point for engineering applications of this material. - Graphical Abstract: (a) Crystal structure of BaSnO 3 . The center ball is Ba and small (red) ball on edge is oxygen and SnO 6 octahedrons are plotted as polyhedron. (b) Electronic band structure along the high symmetry point in the Brillouin zone using the HSE06 hybrid functional. (c) The phonon dispersion curve calculated using the HSE06 hybrid functional (d) Zone center lowest energy F 1u phonon mode. Highlights: ► We report the full hybrid functional calculation of not only the electronic structure but also the phonon structure for BaSnO 3 . ► The band gap calculation of HSE06 revealed an indirect gap with 2.48 eV. ► The effective mass at the conduction band minimum and valence band maximum was calculated. ► In addition, the phonon structure of BSO was calculated using the HSE06 functional. ► Finally, the heat capacity was calculated and compared with the recent experimental result.

  5. First-principles calculations on the four phases of BaTiO3.

    Science.gov (United States)

    Evarestov, Robert A; Bandura, Andrei V

    2012-04-30

    The calculations based on linear combination of atomic orbitals basis functions as implemented in CRYSTAL09 computer code have been performed for cubic, tetragonal, orthorhombic, and rhombohedral modifications of BaTiO(3) crystal. Structural and electronic properties as well as phonon frequencies were obtained using local density approximation, generalized gradient approximation, and hybrid exchange-correlation density functional theory (DFT) functionals for four stable phases of BaTiO(3). A comparison was made between the results of different DFT techniques. It is concluded that the hybrid PBE0 [J. P. Perdew, K. Burke, M. Ernzerhof, J. Chem. Phys. 1996, 105, 9982.] functional is able to predict correctly the structural stability and phonon properties both for cubic and ferroelectric phases of BaTiO(3). The comparative phonon symmetry analysis in BaTiO(3) four phases has been made basing on the site symmetry and irreducible representation indexes for the first time. Copyright © 2012 Wiley Periodicals, Inc.

  6. Organophosphonate functionalized silicon nanowires for DNA hybridization studies

    Energy Technology Data Exchange (ETDEWEB)

    Pedone, Daniel; Cattani Scholz, Anna; Birner, Stefan; Abstreiter, Gerhard [WSI, TU Muenchen (Germany); Dubey, Manish; Schwartz, Jeffrey [Princeton University, NJ (United States); Tornow, Marc [IHT, TU Braunschweig (Germany)

    2007-07-01

    Semiconductor nanowire field effect devices have great appeal for label-free sensing applications due to their sensitivity to surface potential changes that may originate from charged adsorbates. In addition to requiring high sensitivity, suitable passivation and functionalization of the semiconductor surface is obligatory. We have fabricated both freely suspended and oxide-supported silicon nanowires from Silicon-on-Insulator substrates using standard nanopatterning methods (EBL, RIE) and sacrificial oxide layer etching. Subsequent to nanofabrication, the devices were first coated with an hydroxyalkylphosphonate monolayer and then bound via bifunctional linker groups to single stranded DNA or PNA oligonucleotides, respectively. We investigated DNA hybridization on such functionalized nanowires using a difference resistance setup, where subtracting the reference signal from a second wire could be used to exclude most non-specific effects. A net change in surface potential on the order of a few mV could be detected upon addition of the complementary DNA strand. This surface potential change corresponds to the hybridization of about 10{sup 10}cm{sup -2} probe strands according to our model calculations that takes into account the entire hybrid system in electrolyte solution.

  7. First principles study of elemental mercury (Hg0) adsorption on low index CoMnO3 surfaces

    International Nuclear Information System (INIS)

    Ji, Wenchao; Su, Pingru; Tang, Qingli; Cheng, Zhiwen; Shen, Zhemin; Fan, Maohong

    2017-01-01

    Highlights: • Hg 0 adsorption on low index CoMnO 3 surface was predicted by DFT method. • Hg 0 is adsorbed on the CoMnO 3 surface with chemisorption interaction. • Hg 0 has highest adsorption energy on CoMnO 3 (1 0 0) surface with Hg-Mn mechanism. • The electron transfer of Hg 0 has positive relationship with adsorption energy. - Abstract: The density functional theory (DFT) is applied to predict elemental mercury (Hg 0 ) adsorption on CoMnO 3 surface for the first time. GGA/PBE functional were selected to determine the potential Hg 0 capture mechanisms. The results show that Hg 0 has good affinity with CoMnO 3 surfaces with chemical adsorption. The adsorption energy of Hg 0 -CoMnO 3 (1 0 0), Hg 0 -CoMnO 3 (1 0 1) and Hg 0 -CoMnO 3 (1 1 0) are −85.225, −72.305 and −70.729 kJ/mol, respectively. The Hg-Mn and Hg-Co mechanisms were revealed on low index surfaces. Hg 0 was oxidized to its valence state of 0.236 on Mn site in CoMnO 3 (1 0 0) surface. The Hg-Co interaction mechanism occurred on Hg 0 -CoMnO 3 (1 0 1) and Hg 0 -CoMnO 3 (1 1 0) with 0.209e − and 0.189e − transformation, respectively. The PDOS analysis shows that Hg-Mn interaction depends on the hybridization of Hg(s- and d-orbitals) and Mn (s-, p- and d- orbitals). However, Hg-Co interaction stems from s- and d- orbitals of Hg, which only overlapping with d- and p- orbital of Co. Both the adsorption energy and electronic structure analysis indicated that CoMnO 3 catalyst performed excellent in Hg 0 oxidation. Exposing CoMnO 3 (1 0 0) is most favorable in Hg 0 control, which provides theoretical instruction on certain crystal plane synthesis in experiment.

  8. Identification of novel CYP2D7-2D6 hybrids: non-functional and functional variants

    Directory of Open Access Journals (Sweden)

    Andrea Gaedigk

    2010-10-01

    Full Text Available Polymorphic expression of CYP2D6 contributes to the wide range of activity observed for this clinically important drug metabolizing enzyme. In this report we describe novel CYP2D7/2D6 hybrid genes encoding non-functional and functional CYP2D6 protein and a CYP2D7 variant that mimics a CYP2D7/2D6 hybrid gene. Five kb long PCR products encompassing the novel genes were entirely sequenced. A quantitative assay probing in different gene regions was employed to determine CYP2D6 and 2D7 copy number variations and the relative position of the hybrid genes within the locus was assessed by long-range PCR. In addition to the previously known CYP2D6*13 and *66 hybrids, we describe three novel non-functional CYP2D7-2D6 hybrids with gene switching in exon 2 (CYP2D6*79, intron 2 (CYP2D6*80 and intron 5 (CYP2D6*67. A CYP2D7-specific T-ins in exon 1 causes a detrimental frame shift. One subject revealed a CYP2D7 conversion in the 5’-flanking region of a CYP2D6*35 allele, was otherwise unaffected (designated CYP2D6*35B. Finally, three DNAs revealed a CYP2D7 gene with a CYP2D6-like region downstream of exon 9 (designated CYP2D7[REP6]. Quantitative copy number determination, sequence analyses and long-range PCR mapping were in agreement and excluded the presence of additional gene units. Undetected hybrid genes may cause over-estimation of CYP2D6 activity (CYP2D6*1/*1 vs *1/hybrid, etc, but may also cause results that may interfere with the genotype determination. Detection of hybrid events, ‘single’ and tandem, will contribute to more accurate phenotype prediction from genotype data.

  9. Combined hybrid functional and DFT+U calculations for metal chalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Aras, Mehmet; Kılıç, Çetin, E-mail: cetin-kilic@gyte.edu.tr [Department of Physics, Gebze Institute of Technology, Gebze, Kocaeli 41400 (Turkey)

    2014-07-28

    In the density-functional studies of materials with localized electronic states, the local/semilocal exchange-correlation functionals are often either combined with a Hubbard parameter U as in the LDA+U method or mixed with a fraction of exactly computed (Fock) exchange energy yielding a hybrid functional. Although some inaccuracies of the semilocal density approximations are thus fixed to a certain extent, the improvements are not sufficient to make the predictions agree with the experimental data. Here, we put forward the perspective that the hybrid functional scheme and the LDA+U method should be treated as complementary, and propose to combine the range-separated Heyd-Scuseria-Ernzerhof (HSE) hybrid functional with the Hubbard U. We thus present a variety of HSE+U calculations for a set of II-VI semiconductors, consisting of zinc and cadmium monochalcogenides, along with comparison to the experimental data. Our findings imply that an optimal value U{sup *} of the Hubbard parameter could be determined, which ensures that the HSE+U{sup *} calculation reproduces the experimental band gap. It is shown that an improved description not only of the electronic structure but also of the crystal structure and energetics is obtained by adding the U{sup *} term to the HSE functional, proving the utility of HSE+U{sup *} approach in modeling semiconductors with localized electronic states.

  10. PBE-DFT theoretical study of organic photovoltaic materials based on thiophene with 1D and 2D periodic boundary conditions

    Science.gov (United States)

    Saïl, K.; Bassou, G.; Gafour, M. H.; Miloua, F.

    2015-12-01

    Conjugated organic systems such as thiophene are interesting topics in the field of organic solar cells. We theoretically investigate π-conjugated polymers constituted by n units ( n = 1-11) based on the thiophene (Tn) molecule. The computations of the geometries and electronic structures of these compounds are performed using the density functional theory (DFT) at the 6-31 G( d, p) level of theory and the Perdew-Burke-Eenzerhof (PBE) formulation of the generalized gradient approximation with periodic boundary conditions (PBCs) in one (1D) and two (2D) dimensions. Moreover, the electronic properties (HOCO, LUCO, E gap, V oc, and V bi) are determined from 1D and 2D PBC to understand the effect of the number of rings in polythiophene. The absorption properties—excitation energies ( E ex), the maximal absorption wavelength (λmax), oscillator strengths, and light harvesting—efficiency are studied using the time-dependent DFT method. Our studies show that changing the number of thiophene units can effectively modulate the electronic and optical properties. On the other hand, our work demonstrates the efficiency of theoretical calculation in the PBCs.

  11. Study on adsorption of O2 on LaFe1−xMgxO3 (0 1 0) surface by density function theory calculation

    International Nuclear Information System (INIS)

    Liu, Xing; Cheng, Bin; Hu, Jifan; Qin, Hongwei

    2012-01-01

    Highlights: ► Mg-doping can change the electronic properties of LaFeO 3 (0 1 0) surface by decreasing the band gap. ► The position and content of Mg-doping can both affect the ability to adsorb O 2 . ► The strong hybridization between O 2 p and Fe d orbital is the origin of binding mechanism. - Abstract: The adsorption of O 2 on the clean and Mg doped LaFeO 3 (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO 3 (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O 2 was enhanced. When Mg ions were on the first layer, the adsorption of O 2 was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O 2 had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O 2 .

  12. Brain PET and functional MRI: why simultaneously using hybrid PET/MR systems?

    Science.gov (United States)

    Cecchin, Diego; Palombit, Alessandro; Castellaro, Marco; Silvestri, Erica; Bui, Franco; Barthel, Henryk; Sabri, Osama; Corbetta, Maurizio; Bertoldo, Alessandra

    2017-12-01

    In the last 20 years growing attention has been devoted to multimodal imaging. The recent literature is rich of clinical and research studies that have been performed using different imaging modalities on both separate and integrated positron emission tomography (PET) and magnetic resonance (MR) scanners. However, today, hybrid PET/MR systems measure signals related to brain structure, metabolism, neurochemistry, perfusion, and neuronal activity simultaneously, i.e. in the same physiological conditions. A frequently raised question at meeting and symposia is: "Do we really need a hybrid PET/MR system? Are there any advantages over acquiring sequential and separate PET and MR scans?" The present paper is an attempt to answer these questions specifically in relation to PET combined with functional magnetic resonance imaging (fMRI) and arterial spin labeling. We searched (last update: June 2017) the databases PubMed, PMC, Google Scholar and Medline. We also included additional studies if they were cited in the selected articles. No language restriction was applied to the search, but the reviewed articles were all in English. Among all the retrieved articles, we selected only those performed using a hybrid PET/MR system. We found a total of 17 papers that were selected and discussed in three main groups according to the main radiopharmaceutical used: 18F-fluorodeoxyglucose (18F-FDG) (N.=8), 15O-water (15O-H2O) (N.=3) and neuroreceptors (N.=6). Concerning studies using 18F-FDG, simultaneous PET/fMRI revealed that global aspects of functional organization (e.g. graph properties of functional connections) are partially associated with energy consumption. There are remarkable spatial and functional similarities across modalities, but also discrepant findings. More work is needed on this point. There are only a handful of papers comparing blood flow measurements with PET 15O-H2O and MR arterial spin label (ASL) measures, and they show significant regional CBF differences

  13. Functional divergence caused by ancient positive selection of a Drosophila hybrid incompatibility locus.

    Directory of Open Access Journals (Sweden)

    Daniel A Barbash

    2004-06-01

    Full Text Available Interspecific hybrid lethality and sterility are a consequence of divergent evolution between species and serve to maintain the discrete identities of species. The evolution of hybrid incompatibilities has been described in widely accepted models by Dobzhansky and Muller where lineage-specific functional divergence is the essential characteristic of hybrid incompatibility genes. Experimentally tractable models are required to identify and test candidate hybrid incompatibility genes. Several Drosophila melanogaster genes involved in hybrid incompatibility have been identified but none has yet been shown to have functionally diverged in accordance with the Dobzhansky-Muller model. By introducing transgenic copies of the X-linked Hybrid male rescue (Hmr gene into D. melanogaster from its sibling species D. simulans and D. mauritiana, we demonstrate that Hmr has functionally diverged to cause F1 hybrid incompatibility between these species. Consistent with the Dobzhansky-Muller model, we find that Hmr has diverged extensively in the D. melanogaster lineage, but we also find extensive divergence in the sibling-species lineage. Together, these findings implicate over 13% of the amino acids encoded by Hmr as candidates for causing hybrid incompatibility. The exceptional level of divergence at Hmr cannot be explained by neutral processes because we use phylogenetic methods and population genetic analyses to show that the elevated amino-acid divergence in both lineages is due to positive selection in the distant past-at least one million generations ago. Our findings suggest that multiple substitutions driven by natural selection may be a general phenomenon required to generate hybrid incompatibility alleles.

  14. Enzymatic synthesis of lignin-siloxane hybrid functional polymers.

    Science.gov (United States)

    Prasetyo, Endry Nugroho; Kudanga, Tukayi; Fischer, Roman; Eichinger, Reinhard; Nyanhongo, Gibson S; Guebitz, Georg M

    2012-02-01

    This study combines the properties of siloxanes and lignin polymers to produce hybrid functional polymers that can be used as adhesives, coating materials, and/or multifunctionalized thin-coating films. Lignin-silica hybrid copolymers were synthesized by using a sol-gel process. Laccases from Trametes hirsuta were used to oxidize lignosulphonates to enhance their reactivity towards siloxanes and then were incorporated into siloxane precursors undergoing a sol-gel process. In vitro copolymerization studies using pure lignin monomers with aminosilanes or ethoxytrimethylsilane and analysis by ²⁹Si NMR spectroscopy revealed hybrid products. Except for kraft lignin, an increase in lignin concentration positively affected the tensile strength in all samples. Similarly, the viscosity generally increased in all samples with increasing lignin concentration and also affected the curing time. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Evaluating the Performance of DFT Functionals in Assessing the Interaction Energy and Ground-State Charge Transfer of Donor/Acceptor Complexes: Tetrathiafulvalene−Tetracyanoquinodimethane (TTF−TCNQ) as a Model Case

    KAUST Repository

    Sini, Gjergji

    2011-03-08

    We have evaluated the performance of several density functional theory (DFT) functionals for the description of the ground-state electronic structure and charge transfer in donor/acceptor complexes. The tetrathiafulvalene- tetracyanoquinodimethane (TTF-TCNQ) complex has been considered as a model test case. Hybrid functionals have been chosen together with recently proposed long-range corrected functionals (ωB97X, ωB97X-D, LRC-ωPBEh, and LC-ωPBE) in order to assess the sensitivity of the results to the treatment and magnitude of exact exchange. The results show an approximately linear dependence of the ground-state charge transfer with the HOMO TTF-LUMOTCNQ energy gap, which in turn depends linearly on the percentage of exact exchange in the functional. The reliability of ground-state charge transfer values calculated in the framework of a monodeterminantal DFT approach was also examined. © 2011 American Chemical Society.

  16. Evaluating the Performance of DFT Functionals in Assessing the Interaction Energy and Ground-State Charge Transfer of Donor/Acceptor Complexes: Tetrathiafulvalene−Tetracyanoquinodimethane (TTF−TCNQ) as a Model Case

    KAUST Repository

    Sini, Gjergji; Sears, John S.; Brédas, Jean-Luc

    2011-01-01

    We have evaluated the performance of several density functional theory (DFT) functionals for the description of the ground-state electronic structure and charge transfer in donor/acceptor complexes. The tetrathiafulvalene- tetracyanoquinodimethane (TTF-TCNQ) complex has been considered as a model test case. Hybrid functionals have been chosen together with recently proposed long-range corrected functionals (ωB97X, ωB97X-D, LRC-ωPBEh, and LC-ωPBE) in order to assess the sensitivity of the results to the treatment and magnitude of exact exchange. The results show an approximately linear dependence of the ground-state charge transfer with the HOMO TTF-LUMOTCNQ energy gap, which in turn depends linearly on the percentage of exact exchange in the functional. The reliability of ground-state charge transfer values calculated in the framework of a monodeterminantal DFT approach was also examined. © 2011 American Chemical Society.

  17. Solution of the generalized Emden-Fowler equations by the hybrid functions method

    International Nuclear Information System (INIS)

    Tabrizidooz, H R; Marzban, H R; Razzaghi, M

    2009-01-01

    In this paper, we present a numerical algorithm for solving the generalized Emden-Fowler equations, which have many applications in mathematical physics and astrophysics. The method is based on hybrid functions approximations. The properties of hybrid functions, which consist of block-pulse functions and Lagrange interpolating polynomials, are presented. These properties are then utilized to reduce the computation of the generalized Emden-Fowler equations to a system of nonlinear equations. The method is easy to implement and yields very accurate results.

  18. Objective-function Hybridization in Adjoint Seismic Tomography

    Science.gov (United States)

    Yuan, Y. O.; Bozdag, E.; Simons, F.; Gao, F.

    2016-12-01

    In the realm of seismic tomography, we are at the threshold of a new era of huge seismic datasets. However, how to assimilate as much information as possible from every seismogram is still a challenge. Cross-correlation measurements are generally tailored to some window selection algorithms, such as FLEXWIN (Maggie et al. 2008), to balance amplitude differences between seismic phases. However, these measurements naturally favor maximum picks in selected windows. It is also difficult to select all usable portions of seismograms in an optimum way that lots of information is generally lost, particularly the scattered waves. Instantaneous phase type of misfits extract information from every wiggle without cutting seismograms into small pieces, however, dealing with cycle skips at short periods can be challenging. For this purpose, we introduce a flexible hybrid approach for adjoint seismic tomography, to combine various objective functions. We initially focus on phase measurements and propose using instantaneous phase to take into account relatively small-magnitude scattered waves at long periods while using cross-correlation measurements on FLEXWIN windows to select distinct body-wave arrivals without complicating measurements due to non-linearities at short periods. To better deal with cycle skips and reliably measure instantaneous phases we design a new misfit function that incorporates instantaneous phase information implicitly instead of measuring it explicitly, through using normalized analytic signals. We present in our synthetic experiments how instantaneous phase, cross-correlation and their hybridization affect tomographic results. The combination of two different phase measurements in a hybrid approach constitutes progress towards using "anything and everything" in a data set, addressing data quality and measurement challenges simultaneously. We further extend hybridisation of misfit functions for amplitude measurements such as cross-correlation amplitude

  19. Importance of the correlation contribution for local hybrid functionals: range separation and self-interaction corrections.

    Science.gov (United States)

    Arbuznikov, Alexei V; Kaupp, Martin

    2012-01-07

    Local hybrid functionals with their position-dependent exact-exchange admixture are a conceptually simple and promising extension of the concept of a hybrid functional. Local hybrids based on a simple mixing of the local spin density approximation (LSDA) with exact exchange have been shown to be successful for thermochemistry, reaction barriers, and a range of other properties. So far, the combination of this generation of local hybrids with an LSDA correlation functional has been found to give the most favorable results for atomization energies, for a range of local mixing functions (LMFs) governing the exact-exchange admixture. Here, we show that the choice of correlation functional to be used with local hybrid exchange crucially influences the parameterization also of the exchange part as well as the overall performance. A novel ansatz for the correlation part of local hybrids is suggested based on (i) range-separation of LSDA correlation into short-range (SR) and long-range (LR) parts, and (ii) partial or full elimination of the one-electron self-correlation from the SR part. It is shown that such modified correlation functionals allow overall larger exact exchange admixture in thermochemically competitive local hybrids than before. This results in improvements for reaction barriers and for other properties crucially influenced by self-interaction errors, as demonstrated by a number of examples. Based on the range-separation approach, a fresh view on the breakdown of the correlation energy into dynamical and non-dynamical parts is suggested.

  20. A density functional study on adsorption and dissociation of O 2 on Ir(1 0 0) surface

    Science.gov (United States)

    Erikat, I. A.; Hamad, B. A.; Khalifeh, J. M.

    2011-06-01

    The adsorption and the reaction barrier for the dissociation of O 2 on Ir(1 0 0) surface are studied using periodic self-consistent density functional theory (DFT) calculations. Dissociative adsorption is found to be energetically more favorable compared to molecular adsorption. Parallel approaches Prl1 and Prl2 on a hollow site with the same adsorption energy of -3.93 eV for both of them are found to have the most energetically preferred sites of adsorptions among all the studied cases. Hybridization between p-O 2 and d-metal orbitals is responsible for the dissociative adsorption. The minimum energy path is determined by using the nudge elastic band method (NEB). We found that the dissociation occurs immediately and very early in the dissociation path with a small activation barrier (0.26 eV), which means that molecular adsorption of O 2 on Ir(1 0 0) surface occurs at very low temperatures; this is consistent with previous experimental and theoretical studies on Ir surfaces.

  1. Spin-polarized structural, elastic, electronic and magnetic properties of half-metallic ferromagnetism in V-doped ZnSe

    Science.gov (United States)

    Monir, M. El Amine.; Baltache, H.; Murtaza, G.; Khenata, R.; Ahmed, Waleed K.; Bouhemadou, A.; Omran, S. Bin; Seddik, T.

    2015-01-01

    Based on first principles spin-polarized density functional theory, the structural, elastic electronic and magnetic properties of Zn1-xVxSe (for x=0.25, 0.50, 0.75) in zinc blende structure have been studied. The investigation was done using the full-potential augmented plane wave method as implemented in WIEN2k code. The exchange-correlation potential was treated with the generalized gradient approximation PBE-GGA for the structural and elastic properties. Moreover, the PBE-GGA+U approximation (where U is the Hubbard correlation terms) is employed to treat the "d" electrons properly. A comparative study between the band structures, electronic structures, total and partial densities of states and local moments calculated within both GGA and GGA+U schemes is presented. The analysis of spin-polarized band structure and density of states shows the half-metallic ferromagnetic character and are also used to determine s(p)-d exchange constants N0α (conduction band) and N0β (valence band) due to Se(4p)-V(3d) hybridization. It has been clearly evidence that the magnetic moment of V is reduced from its free space change value of 3 μB and the minor atomic magnetic moment on Zn and Se are generated.

  2. Electron, hole and exciton self-trapping in germanium doped silica glass from DFT calculations with self-interaction correction

    International Nuclear Information System (INIS)

    Du Jincheng; Rene Corrales, L.; Tsemekhman, Kiril; Bylaska, Eric J.

    2007-01-01

    Density functional theory (DFT) calculations were employed to understand the refractive index change in germanium doped silica glasses for the trapped states of electronic excitations induced by UV irradiation. Local structure relaxation and excess electron density distribution were calculated upon self-trapping of an excess electron, hole, and exciton in germanium doped silica glass. The results show that both the trapped exciton and excess electron are highly localized on germanium ion and, to some extent, on its oxygen neighbors. Exciton self-trapping is found to lead to the formation of a Ge E' center and a non-bridging hole center. Electron trapping changes the GeO 4 tetrahedron structure into trigonal bi-pyramid with the majority of the excess electron density located along the equatorial line. The self-trapped hole is localized on bridging oxygen ions that are not coordinated to germanium atoms that lead to elongation of the Si-O bonds and change of the Si-O-Si bond angles. We carried out a comparative study of standard DFT versus DFT with a hybrid PBE0 exchange and correlation functional. The results show that the two methods give qualitatively similar relaxed structure and charge distribution for electron and exciton trapping in germanium doped silica glass; however, only the PBE0 functional produces the self-trapped hole

  3. Computing sextic centrifugal distortion constants by DFT: A benchmark analysis on halogenated compounds

    Science.gov (United States)

    Pietropolli Charmet, Andrea; Stoppa, Paolo; Tasinato, Nicola; Giorgianni, Santi

    2017-05-01

    This work presents a benchmark study on the calculation of the sextic centrifugal distortion constants employing cubic force fields computed by means of density functional theory (DFT). For a set of semi-rigid halogenated organic compounds several functionals (B2PLYP, B3LYP, B3PW91, M06, M06-2X, O3LYP, X3LYP, ωB97XD, CAM-B3LYP, LC-ωPBE, PBE0, B97-1 and B97-D) were used for computing the sextic centrifugal distortion constants. The effects related to the size of basis sets and the performances of hybrid approaches, where the harmonic data obtained at higher level of electronic correlation are coupled with cubic force constants yielded by DFT functionals, are presented and discussed. The predicted values were compared to both the available data published in the literature and those obtained by calculations carried out at increasing level of electronic correlation: Hartree-Fock Self Consistent Field (HF-SCF), second order Møller-Plesset perturbation theory (MP2), and coupled-cluster single and double (CCSD) level of theory. Different hybrid approaches, having the cubic force field computed at DFT level of theory coupled to harmonic data computed at increasing level of electronic correlation (up to CCSD level of theory augmented by a perturbational estimate of the effects of connected triple excitations, CCSD(T)) were considered. The obtained results demonstrate that they can represent reliable and computationally affordable methods to predict sextic centrifugal terms with an accuracy almost comparable to that yielded by the more expensive anharmonic force fields fully computed at MP2 and CCSD levels of theory. In view of their reduced computational cost, these hybrid approaches pave the route to the study of more complex systems.

  4. Role of exact exchange in thermally-assisted-occupation density functional theory: A proposal of new hybrid schemes.

    Science.gov (United States)

    Chai, Jeng-Da

    2017-01-28

    We propose hybrid schemes incorporating exact exchange into thermally assisted-occupation-density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] for an improved description of nonlocal exchange effects. With a few simple modifications, global and range-separated hybrid functionals in Kohn-Sham density functional theory (KS-DFT) can be combined seamlessly with TAO-DFT. In comparison with global hybrid functionals in KS-DFT, the resulting global hybrid functionals in TAO-DFT yield promising performance for systems with strong static correlation effects (e.g., the dissociation of H 2 and N 2 , twisted ethylene, and electronic properties of linear acenes), while maintaining similar performance for systems without strong static correlation effects. Besides, a reasonably accurate description of noncovalent interactions can be efficiently achieved through the inclusion of dispersion corrections in hybrid TAO-DFT. Relative to semilocal density functionals in TAO-DFT, global hybrid functionals in TAO-DFT are generally superior in performance for a wide range of applications, such as thermochemistry, kinetics, reaction energies, and optimized geometries.

  5. Theoretical analysis of the electronic, optical and thermal properties of lead strontium telluride alloys Pb1-xSrxTe (x = 0.0-1.0)

    Science.gov (United States)

    Chouit, F.; Sifi, C.; Slimani, M.; Meradji, H.; Ghemid, S.; Khenata, R.; Rai, D. P.; Bin Omran, S.

    2018-02-01

    We have simulated different physical properties of Pb1-xSrxTe semiconductors, using the Ab-initio full potential augmented plane wave (FP-LAPW) method. The two commonly used exchange potentials viz., PBE-GGA and WC-GGA are used along with the most recently developed modified Becke and Johnson (mBJ) potential to study the electronic and optical properties. In this study, we have observed an increase in band gap values as well as the lattice parameter with increasing the concentration of Sr atoms in Pb1-xSrxTe alloys while the bulk modulus and the refractive index have reverse effect. The microscopic origin of the band gap bowing is explained using the approach of Zunger and co-workers. At ambient conditions (p = 0, T = 0), the calculations indicate that Pb1-xSrxTe is a direct band gap semiconductor R-R with x = 0.125, 0.25, 0.375, 0.5, 0.625, 0.75 and 0.875. The refractive indices are also calculated using the FP-LAPW method and the models of Moss, Ravindra and the Herve-Vandame. The obtained results are in consistent with the previous available data. To study the thermal effects, the temperature effect on the lattice parameters, thermal expansions, heat capacities the quasi-harmonic Debye model is applied. The Debye temperature is determined from the non-equilibrium Gibbs function.

  6. Application of vibrational correlation formalism to internal conversion rate: Case study of Cun (n = 3, 6, and 9) and H2/Cu3

    International Nuclear Information System (INIS)

    Chiodo, Sandro Giuseppe; Mineva, Tzonka

    2015-01-01

    This work reports non-radiative internal conversion (IC) rate constants obtained for Cu n with n = 3, 6, and 9 and H 2 on Cu 3 . The Time-Dependent Density Functional Theory (TDDFT) method was employed with three different functionals in order to investigate the electronic structures and the absorption spectra. The performance of the generalized gradient approximation of Perdew, Burke and Ernzerhof (PBE) and the hybrid B3LYP and PBE0 exchange correlation functionals in combination with the SVP and the def2-TZVP basis sets was examined. TDDFT results were used as input data to compute internal conversion rate constants. For this purpose, we have developed a program package. A description of the theoretical background used in our numerical implementation and the program input file is presented. In view of future applications of this program package in photoinduced catalysis, we present the analysis of the IC rate processes for the photodissociation of H 2 on Cu 3 . These results showed the applicability of the method and the computational program to identify the vibrational modes in transition metal clusters giving rise to the largest IC rate constant due to their interactions with the excited electronic states occurring in the hot-electron induced dissociation phenomena

  7. Functionalized graphene oxide/Fe3O4 hybrids for cellular magnetic resonance imaging and fluorescence labeling.

    Science.gov (United States)

    Zhou, Chaohui; Wu, Hui; Wang, Mingliang; Huang, Chusen; Yang, Dapeng; Jia, Nengqin

    2017-09-01

    In this work, we developed a T 2 -weighted contrast agent based on graphene oxide (GO)/Fe 3 O 4 hybrids for efficient cellular magnetic resonance imaging (MRI). The GO/Fe 3 O 4 hybrids were obtained by combining with co-precipitation method and pyrolysis method. The structural, surface and magnetic characteristics of the hybrids were systematically characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), AFM, Raman, FT-IR and XRD. The GO/Fe 3 O 4 hybrids were functionalized by modifying with anionic and cationic polyelectrolyte through layer-by-layer assembling. The fluorescence probe fluorescein isothiocyanate (FITC) was further loaded on the surface of functionalized GO/Fe 3 O 4 hybrids to trace the location of GO/Fe 3 O 4 hybrids in cells. Functionalized GO/Fe 3 O 4 hybrids possess good hydrophilicity, less cytotoxicity, high MRI enhancement with the relaxivity (r 2 ) of 493mM -1 s -1 as well as cellular MRI contrast effect. These obtained results indicated that the functionalized GO/Fe 3 O 4 hybrids could have great potential to be utilized as cellular MRI contrast agents for tumor early diagnosis and monitoring. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Valence electronic structure of cobalt phthalocyanine from an optimally tuned range-separated hybrid functional.

    Science.gov (United States)

    Brumboiu, Iulia Emilia; Prokopiou, Georgia; Kronik, Leeor; Brena, Barbara

    2017-07-28

    We analyse the valence electronic structure of cobalt phthalocyanine (CoPc) by means of optimally tuning a range-separated hybrid functional. The tuning is performed by modifying both the amount of short-range exact exchange (α) included in the hybrid functional and the range-separation parameter (γ), with two strategies employed for finding the optimal γ for each α. The influence of these two parameters on the structural, electronic, and magnetic properties of CoPc is thoroughly investigated. The electronic structure is found to be very sensitive to the amount and range in which the exact exchange is included. The electronic structure obtained using the optimal parameters is compared to gas-phase photo-electron data and GW calculations, with the unoccupied states additionally compared with inverse photo-electron spectroscopy measurements. The calculated spectrum with tuned γ, determined for the optimal value of α = 0.1, yields a very good agreement with both experimental results and with GW calculations that well-reproduce the experimental data.

  9. Rare earth substitutional impurities in germanium: A hybrid density functional theory study

    Science.gov (United States)

    Igumbor, E.; Omotoso, E.; Tunhuma, S. M.; Danga, H. T.; Meyer, W. E.

    2017-10-01

    The Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional by means of density functional theory has been used to model the electronic and structural properties of rare earth (RE) substitutional impurities in germanium (REGe) . The formation and charge state transition energies for the REGe (RE = Ce, Pr, Er and Eu) were calculated. The energy of formation for the neutral charge state of the REGe lies between -0.14 and 3.13 eV. The formation energy result shows that the Pr dopant in Ge (PrGe) has the lowest formation energy of -0.14 eV, and is most energetically favourable under equilibrium conditions. The REGe induced charge state transition levels within the band gap of Ge. Shallow acceptor levels were induced by both the Eu (EuGe) and Pr (PrGe) dopants in Ge. The CeGe and ErGe exhibited properties of negative-U ordering with effective-U values of -0.85 and -1.07 eV, respectively.

  10. Isobaric-Isothermal Molecular Dynamics Utilizing Density Functional Theory: An Assessment of the Structure and Density of Water at Near-Ambient Conditions

    International Nuclear Information System (INIS)

    Schmidt, J.; VandeVondele, J.; Kuo, I.W.; Sebastiani, D.; Siepmann, J.I.; Hutter, J.; Mundy, C.J.

    2009-01-01

    We present herein a comprehensive density functional theory study toward assessing the accuracy of two popular gradient-corrected exchange correlation functionals on the structure and density of liquid water at near ambient conditions in the isobaric-isothermal ensemble. Our results indicate that both PBE and BLYP functionals under predict the density and over structure the liquid. Adding the dispersion correction due to Grimme(1, 2) improves the predicted densities for both BLYP and PBE in a significant manner. Moreover, the addition of the dispersion correction for BLYP yields an oxygen-oxygen radial distribution function in excellent agreement with experiment. Thus, we conclude that one can obtain a very satisfactory model for water using BLYP and a correction for dispersion.

  11. Successes and failures of DFT functionals in acid/base and redox reactions of organic and biochemical interest

    OpenAIRE

    Silva, Pedro J.; Ramos, Maria João

    2011-01-01

    The performance of 18 different DFT functionals in the prediction of absolute and relative energies of organic and biochemical acid/base and redox reactions was evaluated, using MP2 extrapolated to the complete basis set limit and CCSD(T)/aug-cc-pVTZ energies as benchmark. Absolute reduction energies were predicted with relatively large average errors (2–4 kcal mol−1) except for the best functional, PBE0 (1.3 ± 1.2 kcal mol−1). The DFT predictions of relative reduction energies afforded mean ...

  12. Skin-inspired hydrogel-elastomer hybrids with robust interfaces and functional microstructures

    Science.gov (United States)

    Yuk, Hyunwoo; Zhang, Teng; Parada, German Alberto; Liu, Xinyue; Zhao, Xuanhe

    2016-06-01

    Inspired by mammalian skins, soft hybrids integrating the merits of elastomers and hydrogels have potential applications in diverse areas including stretchable and bio-integrated electronics, microfluidics, tissue engineering, soft robotics and biomedical devices. However, existing hydrogel-elastomer hybrids have limitations such as weak interfacial bonding, low robustness and difficulties in patterning microstructures. Here, we report a simple yet versatile method to assemble hydrogels and elastomers into hybrids with extremely robust interfaces (interfacial toughness over 1,000 Jm-2) and functional microstructures such as microfluidic channels and electrical circuits. The proposed method is generally applicable to various types of tough hydrogels and diverse commonly used elastomers including polydimethylsiloxane Sylgard 184, polyurethane, latex, VHB and Ecoflex. We further demonstrate applications enabled by the robust and microstructured hydrogel-elastomer hybrids including anti-dehydration hydrogel-elastomer hybrids, stretchable and reactive hydrogel-elastomer microfluidics, and stretchable hydrogel circuit boards patterned on elastomer.

  13. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, Siddheshwar, E-mail: schopra1@amity.edu

    2017-01-15

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  14. Electronic properties and optical absorption of graphene-polyvinylidene fluoride nanocomposites: A theoretical study

    International Nuclear Information System (INIS)

    Chopra, Siddheshwar

    2017-01-01

    Graphene/polyvinylidene fluoride (graphene/PVDF) nanocomposites were studied using Density functional theory (DFT)/Time dependent density functional theory (TDDFT) calculations. Five nanocomposite configurations were constructed. Electronic properties like binding energy, electronic gap and work function were calculated. The most stable structure was determined. The electronic gap of graphene shifts from semiconducting to conducting, on nanocomposite formation. Workfunction of the most stable nanocomposite was 4.34eV ± 0.05eV, close to that of the pristine graphene (4.33eV ± 0.05eV). Thermochemical analysis showed that the adsorption is spontaneous above ∼870 K, and endothermic in nature. TDDFT calculations were performed for B3LYP, LSDA, BHHLYP and PBE0 functionals. B3LYP and PBE0 are suitable in describing optical absorption. Optical gap of graphene shrinks, and light absorption gets enhanced on nanocomposite formation. - Highlights: • Various properties of graphene-PVDF nanocomposites were studied theoretically. • Electronic gap of graphene shifts to conducting nature, on composite formation. • Adsorption is spontaneous above ∼870 K, and endothermic in nature. • B3LYP and PBE0 functionals are suitable in describing absorption. • Optical absorption gets enhanced on nanocomposite formation.

  15. A density functional theory investigation of the electronic structure and spin moments of magnetite

    KAUST Repository

    Noh, Junghyun

    2014-08-01

    We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts.

  16. A density functional theory investigation of the electronic structure and spin moments of magnetite

    KAUST Repository

    Noh, Junghyun; Osman, Osman I; Aziz, Saadullah G; Winget, Paul; Bredas, Jean-Luc

    2014-01-01

    We present the results of density functional theory (DFT) calculations on magnetite, Fe3O4, which has been recently considered as electrode in the emerging field of organic spintronics. Given the nature of the potential applications, we evaluated the magnetite room-temperature cubic phase in terms of structural, electronic, and magnetic properties. We considered GGA (PBE), GGA + U (PBE + U), and range-separated hybrid (HSE06 and HSE(15%)) functionals. Calculations using HSE06 and HSE(15%) functionals underline the impact that inclusion of exact exchange has on the electronic structure. While the modulation of the band gap with exact exchange has been seen in numerous situations, the dramatic change in the valence band nature and states near the Fermi level has major implications for even a qualitative interpretation of the DFT results. We find that HSE06 leads to highly localized states below the Fermi level while HSE(15%) and PBE + U result in delocalized states around the Fermi level. The significant differences in local magnetic moments and atomic charges indicate that describing room-temperature bulk materials, surfaces and interfaces may require different functionals than their low-temperature counterparts.

  17. Self-consistent hybrid functionals for solids: a fully-automated implementation

    Science.gov (United States)

    Erba, A.

    2017-08-01

    A fully-automated algorithm for the determination of the system-specific optimal fraction of exact exchange in self-consistent hybrid functionals of the density-functional-theory is illustrated, as implemented into the public Crystal program. The exchange fraction of this new class of functionals is self-consistently updated proportionally to the inverse of the dielectric response of the system within an iterative procedure (Skone et al 2014 Phys. Rev. B 89, 195112). Each iteration of the present scheme, in turn, implies convergence of a self-consistent-field (SCF) and a coupled-perturbed-Hartree-Fock/Kohn-Sham (CPHF/KS) procedure. The present implementation, beside improving the user-friendliness of self-consistent hybrids, exploits the unperturbed and electric-field perturbed density matrices from previous iterations as guesses for subsequent SCF and CPHF/KS iterations, which is documented to reduce the overall computational cost of the whole process by a factor of 2.

  18. Modelling of strongly coupled particle growth and aggregation

    International Nuclear Information System (INIS)

    Gruy, F; Touboul, E

    2013-01-01

    The mathematical modelling of the dynamics of particle suspension is based on the population balance equation (PBE). PBE is an integro-differential equation for the population density that is a function of time t, space coordinates and internal parameters. Usually, the particle is characterized by a unique parameter, e.g. the matter volume v. PBE consists of several terms: for instance, the growth rate and the aggregation rate. So, the growth rate is a function of v and t. In classical modelling, the growth and the aggregation are independently considered, i.e. they are not coupled. However, current applications occur where the growth and the aggregation are coupled, i.e. the change of the particle volume with time is depending on its initial value v 0 , that in turn is related to an aggregation event. As a consequence, the dynamics of the suspension does not obey the classical Von Smoluchowski equation. This paper revisits this problem by proposing a new modelling by using a bivariate PBE (with two internal variables: v and v 0 ) and by solving the PBE by means of a numerical method and Monte Carlo simulations. This is applied to a physicochemical system with a simple growth law and a constant aggregation kernel.

  19. A novel hybrid stress-function finite element method immune to severe mesh distortion

    International Nuclear Information System (INIS)

    Cen Song; Zhou Mingjue; Fu Xiangrong

    2010-01-01

    This paper introduces a hybrid stress-function finite element method proposed recently for developing 2D finite element models immune to element shapes. Deferent from the first version of the hybrid-stress element constructed by Pian, the stress function φ of 2D elastic or fracture problem is regarded as the functional variable of the complementary energy functional. Then, the basic analytical solutions of φ are taken as the trial functions for finite element models, and meanwhile, the corresponding unknown stress-function constants are introduced. By using the principle of minimum complementary energy, these unknown stress-function constants can be expressed in terms of the displacements along element edges. Finally, the complementary energy functional can be rewritten in terms of element nodal displacement vector, and thus, the element stiffness matrix of such hybrid-function element can be obtained. As examples, two (8- and 12-node) quadrilateral plane elements and an arbitrary polygonal crack element are constructed by employing different basic analytical solutions of different stress functions. Numerical results show that, the 8- and 12-node plane models can produce the exact solutions for pure bending and linear bending problems, respectively, even the element shape degenerates into triangle and concave quadrangle; and the crack element can also predict accurate results with very low computational cost in analysis of stress-singularity problems.

  20. The normal function of a speciation gene, Odysseus, and its hybrid sterility effect.

    Science.gov (United States)

    Sun, Sha; Ting, Chau-Ti; Wu, Chung-I

    2004-07-02

    To understand how postmating isolation is connected to the normal process of species divergence and why hybrid male sterility is often the first sign of speciation, we analyzed the Odysseus (OdsH) gene of hybrid male sterility in Drosophila. We carried out expression analysis, transgenic study, and gene knockout. The combined evidence suggests that the sterility phenotype represents a novel manifestation of the gene function rather than the reduction or loss of the normal one. The gene knockout experiment identified the normal function of OdsH as a modest enhancement of sperm production in young males. The implication of a weak effect of OdsH on the normal phenotype but a strong influence on hybrid male sterility is discussed in light of Haldane's rule of postmating isolation.

  1. A look at the density functional theory zoo with the advanced GMTKN55 database for general main group thermochemistry, kinetics and noncovalent interactions.

    Science.gov (United States)

    Goerigk, Lars; Hansen, Andreas; Bauer, Christoph; Ehrlich, Stephan; Najibi, Asim; Grimme, Stefan

    2017-12-13

    We present the GMTKN55 benchmark database for general main group thermochemistry, kinetics and noncovalent interactions. Compared to its popular predecessor GMTKN30 [Goerigk and Grimme J. Chem. Theory Comput., 2011, 7, 291], it allows assessment across a larger variety of chemical problems-with 13 new benchmark sets being presented for the first time-and it also provides reference values of significantly higher quality for most sets. GMTKN55 comprises 1505 relative energies based on 2462 single-point calculations and it is accessible to the user community via a dedicated website. Herein, we demonstrate the importance of better reference values, and we re-emphasise the need for London-dispersion corrections in density functional theory (DFT) treatments of thermochemical problems, including Minnesota methods. We assessed 217 variations of dispersion-corrected and -uncorrected density functional approximations, and carried out a detailed analysis of 83 of them to identify robust and reliable approaches. Double-hybrid functionals are the most reliable approaches for thermochemistry and noncovalent interactions, and they should be used whenever technically feasible. These are, in particular, DSD-BLYP-D3(BJ), DSD-PBEP86-D3(BJ), and B2GPPLYP-D3(BJ). The best hybrids are ωB97X-V, M052X-D3(0), and ωB97X-D3, but we also recommend PW6B95-D3(BJ) as the best conventional global hybrid. At the meta-generalised-gradient (meta-GGA) level, the SCAN-D3(BJ) method can be recommended. Other meta-GGAs are outperformed by the GGA functionals revPBE-D3(BJ), B97-D3(BJ), and OLYP-D3(BJ). We note that many popular methods, such as B3LYP, are not part of our recommendations. In fact, with our results we hope to inspire a change in the user community's perception of common DFT methods. We also encourage method developers to use GMTKN55 for cross-validation studies of new methodologies.

  2. First principles study of elemental mercury (Hg{sup 0}) adsorption on low index CoMnO{sub 3} surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Wenchao; Su, Pingru; Tang, Qingli; Cheng, Zhiwen [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China); Shen, Zhemin, E-mail: zmshen@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China); Fan, Maohong [Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, Wyoming, 82071 (United States); School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, 30332 (United States)

    2017-06-30

    Highlights: • Hg{sup 0} adsorption on low index CoMnO{sub 3} surface was predicted by DFT method. • Hg{sup 0} is adsorbed on the CoMnO{sub 3} surface with chemisorption interaction. • Hg{sup 0} has highest adsorption energy on CoMnO{sub 3} (1 0 0) surface with Hg-Mn mechanism. • The electron transfer of Hg{sup 0} has positive relationship with adsorption energy. - Abstract: The density functional theory (DFT) is applied to predict elemental mercury (Hg{sup 0}) adsorption on CoMnO{sub 3} surface for the first time. GGA/PBE functional were selected to determine the potential Hg{sup 0} capture mechanisms. The results show that Hg{sup 0} has good affinity with CoMnO{sub 3} surfaces with chemical adsorption. The adsorption energy of Hg{sup 0}-CoMnO{sub 3} (1 0 0), Hg{sup 0}-CoMnO{sub 3} (1 0 1) and Hg{sup 0}-CoMnO{sub 3} (1 1 0) are −85.225, −72.305 and −70.729 kJ/mol, respectively. The Hg-Mn and Hg-Co mechanisms were revealed on low index surfaces. Hg{sup 0} was oxidized to its valence state of 0.236 on Mn site in CoMnO{sub 3} (1 0 0) surface. The Hg-Co interaction mechanism occurred on Hg{sup 0}-CoMnO{sub 3} (1 0 1) and Hg{sup 0}-CoMnO{sub 3} (1 1 0) with 0.209e{sup −} and 0.189e{sup −} transformation, respectively. The PDOS analysis shows that Hg-Mn interaction depends on the hybridization of Hg(s- and d-orbitals) and Mn (s-, p- and d- orbitals). However, Hg-Co interaction stems from s- and d- orbitals of Hg, which only overlapping with d- and p- orbital of Co. Both the adsorption energy and electronic structure analysis indicated that CoMnO{sub 3} catalyst performed excellent in Hg{sup 0} oxidation. Exposing CoMnO{sub 3} (1 0 0) is most favorable in Hg{sup 0} control, which provides theoretical instruction on certain crystal plane synthesis in experiment.

  3. Synthesis and photophysical properties of pyrene-functionalized nano-SiO{sub 2} hybrids in solutions and doped-PMMA thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wen-Jie; He, Wen-Li; Yu, Hong-Yu [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Huang, Hong-Xiang [State Key Laboratory of Molecular Engineering of Polymers, Fudan University, 220 Handan Road, Shanghai 200433 (China); Chen, Meng [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China); Qian, Dong-Jin, E-mail: djqian@fudan.edu.cn [Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China)

    2017-01-15

    Luminescent pyrene-functionalized nano-SiO{sub 2} (nano-SiO{sub 2}Pyr) hybrids were synthesized and characterized using thermogravimetry, infrared, UV–vis absorption and, X-ray photoelectron spectroscopy, as well as field emission transmission electron microscopy (FETEM). The organic substituents immobilized on the nano-SiO{sub 2}Pyr hybrids accounted for approximately 10% of the total weight. Polyethylene glycol 200 (PEG200) was found to be the most suitable solvent to suspend the nano-SiO{sub 2}Pyr hybrids compared to other commonly used organic solvents. FETEM images indicated an average SiO{sub 2} nanoparticle diameter of approximately 12 nm and a 1- to 2-nm thick organic species functionalization layer. Several emission peaks were recorded at wavelengths of 380–580 nm and were designated as emissions arising from either the monomer or excimer of the pyrene substituents. Excimer formation was concentration and solvent polarity dependent, with higher concentrations and a stronger solvent polarity benefiting excimer formation. Further, nano-SiO{sub 2}Pyr hybrids were doped in poly(methyl methacrylate) (PMMA) thin films; fluorescence spectra indicated that the excimer could be formed almost exclusively from neighboring nano-SiO{sub 2}Pyr hybrids. Time-resolved fluorescence decays revealed that the emission lifetimes of nano-SiO{sub 2}Pyr monomers and excimers were approximately 190 ns and 65–100 ns in the PEG200 solution, respectively, which was shortened to 0.45 ns to tens of ns in doped PMMA thin films, depending on the nano-hybrid concentration. Thus, the present study not only provides a method to prepare luminescent nano-materials but also a route to investigate excimer formation in solutions and thin films. - Highlights: • Luminescent pyrene-functionalized nano-SiO{sub 2}Pyr hybrids were prepared. • A 1- to 2- nm thick organic functionalization layer on nano-SiO{sub 2} was observed. • Formation of pyrene excimer was concentration and solvent

  4. Spin-Orbit Effect on the Molecular Properties of TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4): A Density Functional Theory and Ab Initio Study.

    Science.gov (United States)

    Moon, Jiwon; Kim, Joonghan

    2016-09-29

    Density functional theory (DFT) and ab initio calculations, including spin-orbit coupling (SOC), were performed to investigate the spin-orbit (SO) effect on the molecular properties of tellurium halides, TeXn (X = F, Cl, Br, and I; n = 1, 2, and 4). SOC elongates the Te-X bond and slightly reduces the vibrational frequencies. Consideration of SOC leads to better agreement with experimental values. Møller-Plesset second-order perturbation theory (MP2) seriously underestimates the Te-X bond lengths. In contrast, B3LYP significantly overestimates them. SO-PBE0 and multireference configuration interactions with the Davidson correction (MRCI+Q), which include SOC via a state-interaction approach, give the Te-I bond length of TeI2 that matches the experimental value. On the basis of the calculated thermochemical energy and optimized molecular structure, TeI4 is unlikely to be stable. The use of PBE0 including SOC is strongly recommended for predicting the molecular properties of Te-containing compounds.

  5. Graphene-based hybrid structures combined with functional materials of ferroelectrics and semiconductors.

    Science.gov (United States)

    Jie, Wenjing; Hao, Jianhua

    2014-06-21

    Fundamental studies and applications of 2-dimensional (2D) graphene may be deepened and broadened via combining graphene sheets with various functional materials, which have been extended from the traditional insulator of SiO2 to a versatile range of dielectrics, semiconductors and metals, as well as organic compounds. Among them, ferroelectric materials have received much attention due to their unique ferroelectric polarization. As a result, many attractive characteristics can be shown in graphene/ferroelectric hybrid systems. On the other hand, graphene can be integrated with conventional semiconductors and some newly-discovered 2D layered materials to form distinct Schottky junctions, yielding fascinating behaviours and exhibiting the potential for various applications in future functional devices. This review article is an attempt to illustrate the most recent progress in the fabrication, operation principle, characterization, and promising applications of graphene-based hybrid structures combined with various functional materials, ranging from ferroelectrics to semiconductors. We focus on mechanically exfoliated and chemical-vapor-deposited graphene sheets integrated in numerous advanced devices. Some typical hybrid structures have been highlighted, aiming at potential applications in non-volatile memories, transparent flexible electrodes, solar cells, photodetectors, and so on.

  6. Study on adsorption of O{sub 2} on LaFe{sub 1-x}Mg{sub x}O{sub 3} (0 1 0) surface by density function theory calculation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xing, E-mail: liuxing0108@mail.sdu.edu.cn [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Cheng, Bin [Civil Engineer Department, Qingdao Technological University (Linyi), Easter Outer Ring Road 1, Linyi, 273400 (China); Hu, Jifan; Qin, Hongwei [State Key Laboratory of Crystal Material, Department of Physics, Shandong University, Hongjialou 5, Jinan, 250100 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. Black-Right-Pointing-Pointer The position and content of Mg-doping can both affect the ability to adsorb O{sub 2}. Black-Right-Pointing-Pointer The strong hybridization between O{sub 2} p and Fe d orbital is the origin of binding mechanism. - Abstract: The adsorption of O{sub 2} on the clean and Mg doped LaFeO{sub 3} (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO{sub 3} (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O{sub 2} was enhanced. When Mg ions were on the first layer, the adsorption of O{sub 2} was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O{sub 2} had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O{sub 2}.

  7. Hybrid cooling tower Neckarwestheim 2 cooling function, emission, plume dispersion

    International Nuclear Information System (INIS)

    Braeuning, G.; Ernst, G.; Maeule, R.; Necker, P.

    1990-01-01

    The fan-assisted hybrid cooling tower of the 1300 MW power plant Gemeinschafts-Kernkraftwerk Neckarwestheim 2 was designed and constructed based on results from theoretical and experimental studies and experiences from a smaller prototype. The wet part acts in counterflow. The dry part is arranged above the wet part. Each part contains 44 fans. Special attention was payed to the ducts which mix the dry into the wet plume. The cooling function and state, mass flow and contents of the emission were measured. The dispersion of the plume in the atmosphere was observed. The central results are presented in this paper. The cooling function corresponds to the predictions. The content of drifted cooling water in the plume is extremely low. The high velocity of the plume in the exit causes an undisturbed flow into the atmosphere. The hybrid operation reduces visible plumes strongly, especially in warmer and drier ambient air

  8. Analytic derivatives for perturbatively corrected ''double hybrid'' density functionals: Theory, implementation, and applications

    International Nuclear Information System (INIS)

    Neese, Frank; Schwabe, Tobias; Grimme, Stefan

    2007-01-01

    A recently proposed new family of density functionals [S. Grimme, J. Chem. Phys. 124, 34108 (2006)] adds a fraction of nonlocal correlation as a new ingredient to density functional theory (DFT). This fractional correlation energy is calculated at the level of second-order many-body perturbation theory (PT2) and replaces some of the semilocal DFT correlation of standard hybrid DFT methods. The new ''double hybrid'' functionals (termed, e.g., B2-PLYP) contain only two empirical parameters that have been adjusted in thermochemical calculations on parts of the G2/3 benchmark set. The methods have provided the lowest errors ever obtained by any DFT method for the full G3 set of molecules. In this work, the applicability of the new functionals is extended to the exploration of potential energy surfaces with analytic gradients. The theory of the analytic gradient largely follows the standard theory of PT2 gradients with some additional subtleties due to the presence of the exchange-correlation terms in the self-consistent field operator. An implementation is reported for closed-shell as well as spin-unrestricted reference determinants. Furthermore, the implementation includes external point charge fields and also accommodates continuum solvation models at the level of the conductor like screening model. The density fitting resolution of the identity (RI) approximation can be applied to the evaluation of the PT2 part with large gains in computational efficiency. For systems with ∼500-600 basis functions the evaluation of the double hybrid gradient is approximately four times more expensive than the calculation of the standard hybrid DFT gradient. Extensive test calculations are provided for main group elements and transition metal containing species. The results reveal that the B2-PLYP functional provides excellent molecular geometries that are superior compared to those from standard DFT and MP2

  9. Establishment of hybridized focus measure functions as a universal method for autofocusing

    Science.gov (United States)

    Shah, Mohammad Imran; Mishra, Smriti; Rout, Chittaranjan

    2017-12-01

    Exact focusing is essential for any automatic image capturing system. Performances of focus measure functions (FMFs) used for autofocusing are sensitive to image contents and imaging systems. Therefore, identification of universal FMF assumes a lot of significance. Eight FMFs were hybridized in pairs of two and implemented simultaneously on a single stack to calculate the hybrid focus measure. In total, 28 hybrid FMFs (HFMFs) and eight FMFs were implemented on stacks of images from three different imaging modalities. Performance of FMFs was found to the best at 50% region sampling. Accuracy, focus error, and false maxima were calculated to evaluate the performance of each FMF. Nineteen HFMFs provided >90% accuracy. Image distortion (noise, contrast, saturation, illumination, etc.) was performed to evaluate robustness of HFMFs. Hybrid of tenengrad variance and steerable filter-based (VGRnSFB) FMFs was identified as the most robust and accurate function with an accuracy of ≥90% and a relatively lower focus error and false maxima rate. Sharpness of focus curve of VGRnSFB along with eight individual FMFs was also computed to determine the efficacy of HFMF for the optimization process. VGRnSFB HFMF may be implemented for automated capturing of an image for any imaging system.

  10. Parkia biglobosa Improves Mitochondrial Functioning and Protects against Neurotoxic Agents in Rat Brain Hippocampal Slices

    Directory of Open Access Journals (Sweden)

    Kayode Komolafe

    2014-01-01

    Full Text Available Objective. Methanolic leaf extracts of Parkia biglobosa, PBE, and one of its major polyphenolic constituents, catechin, were investigated for their protective effects against neurotoxicity induced by different agents on rat brain hippocampal slices and isolated mitochondria. Methods. Hippocampal slices were preincubated with PBE (25, 50, 100, or 200 µg/mL or catechin (1, 5, or 10 µg/mL for 30 min followed by further incubation with 300 µM H2O2, 300 µM SNP, or 200 µM PbCl2 for 1 h. Effects of PBE and catechin on SNP- or CaCl2-induced brain mitochondrial ROS formation and mitochondrial membrane potential (ΔΨm were also determined. Results. PBE and catechin decreased basal ROS generation in slices and blunted the prooxidant effects of neurotoxicants on membrane lipid peroxidation and nonprotein thiol contents. PBE rescued hippocampal cellular viability from SNP damage and caused a significant boost in hippocampus Na+, K+-ATPase activity but with no effect on the acetylcholinesterase activity. Both PBE and catechin also mitigated SNP- or CaCl2-dependent mitochondrial ROS generation. Measurement by safranine fluorescence however showed that the mild depolarization of the ΔΨm by PBE was independent of catechin. Conclusion. The results suggest that the neuroprotective effect of PBE is dependent on its constituent antioxidants and mild mitochondrial depolarization propensity.

  11. Phonon spectra of elpasolites Cs{sub 2}NaRF{sub 6} (R=Y,Yb): Ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Chernyshev, Vladimir, E-mail: Vladimir.Chernyshev@urfu.ru; Petrov, Vladislav; Nikiforov, Anatoliy; Zakiryanov, Dmitriy [Ural Federal University, Ekaterinburg (Russian Federation)

    2015-12-07

    The influence of hydrostatic pressure on structure and dynamics of a crystal lattice of elpasolites Cs{sub 2}NaYbF{sub 6} and Cs{sub 2}NaYF{sub 6} (S.G. 225) within ab initio approach is investigated. Frequencies and irreducible representations (irreps) of phonon modes are determined. Elastic constants are calculated. The calculations are carried out within MO LCAO approach using DFT method with hybrid functionalities of B3LYP and PBE0 in CRYSTAL09 periodic code. For the description of rare earth ion the pseudopotential replacing internal orbitals including 4f orbitals was used. External 5s and 5p orbitals defining chemical bond were described by valence basis sets.

  12. Application of zone-folding approach to the first-principles estimation of thermodynamic properties of carbon and ZrS2 -based nanotubes.

    Science.gov (United States)

    Bandura, Andrei V; Porsev, Vitaly V; Evarestov, Robert A

    2016-03-15

    A zone-folding (ZF) approach is applied for the estimation of the phonon contributions to thermodynamic properties of carbon-and ZrS2 -based nanotubes (NTs) of hexagonal morphology with different chiralities. The results obtained are compared with those from the direct calculation of the thermodynamic properties of NTs using PBE0 hybrid exchange-correlation functional. The phonon contribution to the stability of NTs proved to be negligible for the internal energy and small for the Helmholtz free energy. It is found that the ZF approach allows us an accurate estimation of phonon contributions to internal energy, but slightly overestimates the phonon contributions to entropy. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  13. Density-functional approaches to noncovalent interactions: a comparison of dispersion corrections (DFT-D), exchange-hole dipole moment (XDM) theory, and specialized functionals.

    Science.gov (United States)

    Burns, Lori A; Vázquez-Mayagoitia, Alvaro; Sumpter, Bobby G; Sherrill, C David

    2011-02-28

    A systematic study of techniques for treating noncovalent interactions within the computationally efficient density functional theory (DFT) framework is presented through comparison to benchmark-quality evaluations of binding strength compiled for molecular complexes of diverse size and nature. In particular, the efficacy of functionals deliberately crafted to encompass long-range forces, a posteriori DFT+dispersion corrections (DFT-D2 and DFT-D3), and exchange-hole dipole moment (XDM) theory is assessed against a large collection (469 energy points) of reference interaction energies at the CCSD(T) level of theory extrapolated to the estimated complete basis set limit. The established S22 [revised in J. Chem. Phys. 132, 144104 (2010)] and JSCH test sets of minimum-energy structures, as well as collections of dispersion-bound (NBC10) and hydrogen-bonded (HBC6) dissociation curves and a pairwise decomposition of a protein-ligand reaction site (HSG), comprise the chemical systems for this work. From evaluations of accuracy, consistency, and efficiency for PBE-D, BP86-D, B97-D, PBE0-D, B3LYP-D, B970-D, M05-2X, M06-2X, ωB97X-D, B2PLYP-D, XYG3, and B3LYP-XDM methodologies, it is concluded that distinct, often contrasting, groups of these elicit the best performance within the accessible double-ζ or robust triple-ζ basis set regimes and among hydrogen-bonded or dispersion-dominated complexes. For overall results, M05-2X, B97-D3, and B970-D2 yield superior values in conjunction with aug-cc-pVDZ, for a mean absolute deviation of 0.41 - 0.49 kcal/mol, and B3LYP-D3, B97-D3, ωB97X-D, and B2PLYP-D3 dominate with aug-cc-pVTZ, affording, together with XYG3/6-311+G(3df,2p), a mean absolute deviation of 0.33 - 0.38 kcal/mol.

  14. Soft Sensing of Key State Variables in Fermentation Process Based on Relevance Vector Machine with Hybrid Kernel Function

    Directory of Open Access Journals (Sweden)

    Xianglin ZHU

    2014-06-01

    Full Text Available To resolve the online detection difficulty of some important state variables in fermentation process with traditional instruments, a soft sensing modeling method based on relevance vector machine (RVM with a hybrid kernel function is presented. Based on the characteristic analysis of two commonly-used kernel functions, that is, local Gaussian kernel function and global polynomial kernel function, a hybrid kernel function combing merits of Gaussian kernel function and polynomial kernel function is constructed. To design optimal parameters of this kernel function, the particle swarm optimization (PSO algorithm is applied. The proposed modeling method is used to predict the value of cell concentration in the Lysine fermentation process. Simulation results show that the presented hybrid-kernel RVM model has a better accuracy and performance than the single kernel RVM model.

  15. DFT study on the standard electrode potentials of imidazole, tetrathiafulvalene, and tetrathiafulvalene-imidazole.

    Science.gov (United States)

    Tugsuz, Tugba

    2010-12-30

    Extensive DFT calculations on the standard electrode potentials of imidazole (Im), tetrathiafulvalene (TTF), and 2-, 4-, and 5-TTF-Im were carried out. Geometries and Gibbs free energies of H-bonded dimer, anion, protonated cation, and neutral structures of Im, mono- and dication, and neutral structures of TTF in gas and acetonitrile solvent were computed by using 10 hybrid density functionals (B3LYP, TPSSH, PBEH1PBE, M06, M062X, X3LYP, BMK, B1B95, M05, M052X) combined with the TZVP basis set. CPCM and SMD solvation models were applied to predict the Gibbs free energies of molecules in acetonitrile solvent. Frequency calculations were carried out for all structures, and none of them has been found to exhibit any imaginary frequency. Finally, the BMK hybrid functional was selected for computation of the standard electrode potential of TTF-Im, because it gives the most accurate values in both Im and TTF, differing by 0.05 V from the experimental ones. Moreover, frequencies from the BMK functional are reasonably close to the experimental ones. The standard electrode potentials of 2-, 4-, and 5-TTF-Im predicted for two-electron oxidation are 0.946, 0.870, and 0.839 V in CPCM and 0.927, 0.866, and 0.824 V in SMD. For one-electron oxidation these are 0.491, 0.421, and 0.400 V in CPCM and 0.476, 0.377, and 0.360 V in SMD, respectively.

  16. Towards an ankle neuroprosthesis for hybrid robotics: Concepts and current sources for functional electrical stimulation.

    Science.gov (United States)

    Casco, S; Fuster, I; Galeano, R; Moreno, J C; Pons, J L; Brunetti, F

    2017-07-01

    Hybrid rehabilitation robotics combine neuro-prosthetic devices (close-loop functional electrical stimulation systems) and traditional robotic structures and actuators to explore better therapies and promote a more efficient motor function recovery or compensation. Although hybrid robotics and ankle neuroprostheses (NPs) have been widely developed over the last years, there are just few studies on the use of NPs to electrically control both ankle flexion and extension to promote ankle recovery and improved gait patterns in paretic limbs. The aim of this work is to develop an ankle NP specifically designed to work in the field of hybrid robotics. This article presents early steps towards this goal and makes a brief review about motor NPs and Functional Electrical Stimulation (FES) principles and most common devices used to aid the ankle functioning during the gait cycle. It also shows a current sources analysis done in this framework, in order to choose the best one for this intended application.

  17. The Peroxisomal Enzyme L-PBE Is Required to Prevent the Dietary Toxicity of Medium-Chain Fatty Acids

    Directory of Open Access Journals (Sweden)

    Jun Ding

    2013-10-01

    Full Text Available Specific metabolic pathways are activated by different nutrients to adapt the organism to available resources. Although essential, these mechanisms are incompletely defined. Here, we report that medium-chain fatty acids contained in coconut oil, a major source of dietary fat, induce the liver ω-oxidation genes Cyp4a10 and Cyp4a14 to increase the production of dicarboxylic fatty acids. Furthermore, these activate all ω- and β-oxidation pathways through peroxisome proliferator activated receptor (PPAR α and PPARγ, an activation loop normally kept under control by dicarboxylic fatty acid degradation by the peroxisomal enzyme L-PBE. Indeed, L-pbe−/− mice fed coconut oil overaccumulate dicarboxylic fatty acids, which activate all fatty acid oxidation pathways and lead to liver inflammation, fibrosis, and death. Thus, the correct homeostasis of dicarboxylic fatty acids is a means to regulate the efficient utilization of ingested medium-chain fatty acids, and its deregulation exemplifies the intricate relationship between impaired metabolism and inflammation.

  18. Energy down converting organic fluorophore functionalized mesoporous silica hybrids for monolith-coated light emitting diodes

    Directory of Open Access Journals (Sweden)

    Markus Börgardts

    2017-04-01

    Full Text Available The covalent attachment of organic fluorophores in mesoporous silica matrices for usage as energy down converting phosphors without employing inorganic transition or rare earth metals is reported in this article. Triethoxysilylpropyl-substituted derivatives of the blue emitting perylene, green emitting benzofurazane, and red emitting Nile red were synthesized and applied in the synthesis of mesoporous hybrid materials by postsynthetic grafting to commercially available MCM-41. These individually dye-functionalized hybrid materials are mixed in variable ratios to furnish a powder capable of emitting white light with CIE chromaticity coordinates of x = 0.33, y = 0.33 and an external quantum yield of 4.6% upon irradiation at 410 nm. Furthermore, as a proof of concept two different device setups of commercially available UV light emitting diodes, are coated with silica monoliths containing the three triethoxysilylpropyl-substituted fluorophore derivatives. These coatings are able to convert the emitted UV light into light with correlated color temperatures of very cold white (41100 K, 10700 K as well as a greenish white emission with correlated color temperatures of about 5500 K.

  19. The effect of additional equilibrium stress functions on the three-node hybrid-mixed curved beam element

    International Nuclear Information System (INIS)

    Kim, Jin Gon; Park, Yong Kuk

    2008-01-01

    To develop an effective hybrid-mixed element, it is extremely critical as to how to assume the stress field. This research article demonstrates the effect of additional equilibrium stress functions to enhance the numerical performance of the locking-free three-node hybrid-mixed curved beam element, proposed in Saleeb and Chang's previous work. It is exceedingly complicated or even infeasible to determine the stress functions to satisfy fully both the equilibrium conditions and suppression of kinematic deformation modes in the three-node hybrid-mixed formulation. Accordingly, the additional stress functions to satisfy partially or fully equilibrium conditions are incorporated in this study. Several numerical examples for static and dynamic problems confirm that the newly proposed element with these additional stress functions is highly effective regardless of the slenderness ratio and curvature of arches in static and dynamic analyses

  20. Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?

    Science.gov (United States)

    Kesharwani, Manoj K; Brauer, Brina; Martin, Jan M L

    2015-03-05

    We have obtained uniform frequency scaling factors λ(harm) (for harmonic frequencies), λ(fund) (for fundamentals), and λ(ZPVE) (for zero-point vibrational energies (ZPVEs)) for the Weigend-Ahlrichs and other selected basis sets for MP2, SCS-MP2, and a variety of DFT functionals including double hybrids. For selected levels of theory, we have also obtained scaling factors for true anharmonic fundamentals and ZPVEs obtained from quartic force fields. For harmonic frequencies, the double hybrids B2PLYP, B2GP-PLYP, and DSD-PBEP86 clearly yield the best performance at RMSD = 10-12 cm(-1) for def2-TZVP and larger basis sets, compared to 5 cm(-1) at the CCSD(T) basis set limit. For ZPVEs, again, the double hybrids are the best performers, reaching root-mean-square deviations (RMSDs) as low as 0.05 kcal/mol, but even mainstream functionals like B3LYP can get down to 0.10 kcal/mol. Explicitly anharmonic ZPVEs only are marginally more accurate. For fundamentals, however, simple uniform scaling is clearly inadequate.

  1. General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory.

    Science.gov (United States)

    Roch, Loïc M; Baldridge, Kim K

    2017-10-04

    A general optimization procedure towards the development and implementation of a new family of minimal parameter spin-component-scaled double-hybrid (mSD) density functional theory (DFT) is presented. The nature of the proposed exchange-correlation functional establishes a methodology with minimal empiricism. This new family of double-hybrid (DH) density functionals is demonstrated using the PBEPBE functional, illustrating the optimization procedure to the mSD-PBEPBE method, and the performance characteristics shown for a set of non-covalent complexes covering a broad regime of weak interactions. With only two parameters, mSD-PBEPBE and its cost-effective counterpart, RI-mSD-PBEPBE, show a mean absolute error of ca. 0.4 kcal mol -1 averaged over 66 weak interacting systems. Following a successive 2D-grid refinement for a CBS extrapolation of the coefficients, the optimization procedure can be recommended for the design and implementation of a variety of additional DH methods using any of the plethora of currently available functionals.

  2. Nucleon polarizabilities from deuteron Compton scattering within a Green's function hybrid approach

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, R.P.; Hemmert, T.R. [Technische Universitaet Muenchen, Institut fuer Theoretische Physik (T39), Physik-Department, Garching (Germany); Griesshammer, H.W. [Technische Universitaet Muenchen, Institut fuer Theoretische Physik (T39), Physik-Department, Garching (Germany); Universitaet Erlangen-Nuernberg, Institut fuer Theoretische Physik III, Naturwissenschaftliche Fakultaet I, Erlangen (Germany); The George Washington University, Center for Nuclear Studies, Department of Physics, Washington DC (United States)

    2010-10-15

    We examine elastic Compton scattering from the deuteron for photon energies ranging from zero to 100MeV, using state-of-the-art deuteron wave functions and NN potentials. Nucleon-nucleon rescattering between emission and absorption of the two photons is treated by Green's functions in order to ensure gauge invariance and the correct Thomson limit. With this Green's function hybrid approach, we fulfill the low-energy theorem of deuteron Compton scattering and there is no significant dependence on the deuteron wave function used. Concerning the nucleon structure, we use the chiral effective field theory with explicit {delta} (1232) degrees of freedom within the small-scale expansion up to leading-one-loop order. Agreement with available data is good at all energies. Our 2-parameter fit to all elastic {gamma} d data leads to values for the static isoscalar dipole polarizabilities which are in excellent agreement with the isoscalar Baldin sum rule. Taking this value as additional input, we find {alpha}{sub E}{sup s} = (11.3{+-}0.7(stat){+-}0.6(Baldin){+-}1(theory)){sup .}10{sup -4} fm{sup 3} and {beta}{sub M}{sup s} = (3.2{+-}0.7(stat){+-}0.6(Baldin){+-}1(theory)){sup .}10{sup -4} fm{sup 3} and conclude by comparison to the proton numbers that neutron and proton polarizabilities are the same within rather small errors. (orig.)

  3. Shannon Entropy in Atoms: A Test for the Assessment of Density Functionals in Kohn-Sham Theory

    Directory of Open Access Journals (Sweden)

    Claudio Amovilli

    2018-05-01

    Full Text Available Electron density is used to compute Shannon entropy. The deviation from the Hartree–Fock (HF of this quantity has been observed to be related to correlation energy. Thus, Shannon entropy is here proposed as a valid quantity to assess the quality of an energy density functional developed within Kohn–Sham theory. To this purpose, results from eight different functionals, representative of Jacob’s ladder, are compared with accurate results obtained from diffusion quantum Monte Carlo (DMC computations. For three series of atomic ions, our results show that the revTPSS and the PBE0 functionals are the best, whereas those based on local density approximation give the largest discrepancy from DMC Shannon entropy.

  4. Multi-functional quantum router using hybrid opto-electromechanics

    Science.gov (United States)

    Ma, Peng-Cheng; Yan, Lei-Lei; Chen, Gui-Bin; Li, Xiao-Wei; Liu, Shu-Jing; Zhan, You-Bang

    2018-03-01

    Quantum routers engineered with multiple frequency bands play a key role in quantum networks. We propose an experimentally accessible scheme for a multi-functional quantum router, using photon-phonon conversion in a hybrid opto-electromechanical system. Our proposed device functions as a bidirectional, tunable multi-channel quantum router, and demonstrates the possibility to route single optical photons bidirectionally and simultaneously to three different output ports, by adjusting the microwave power. Further, the device also behaves as an interswitching unit for microwave and optical photons, yielding probabilistic routing of microwave (optical) signals to optical (microwave) outports. With respect to potential application, we verify the insignificant influence from vacuum and thermal noises in the performance of the router under cryogenic conditions.

  5. Functional Abstraction of Stochastic Hybrid Systems

    NARCIS (Netherlands)

    Bujorianu, L.M.; Blom, Henk A.P.; Hermanns, H.

    2006-01-01

    The verification problem for stochastic hybrid systems is quite difficult. One method to verify these systems is stochastic reachability analysis. Concepts of abstractions for stochastic hybrid systems are needed to ease the stochastic reachability analysis. In this paper, we set up different ways

  6. A-centers in silicon studied with hybrid density functional theory

    KAUST Repository

    Wang, Hao; Chroneos, Alexander; Londos, C. A.; Schwingenschlö gl, Udo; Sgourou, E. N.

    2013-01-01

    Density functional theory employing hybrid functional is used to gain fundamental insight into the interaction of vacancies with oxygen interstitials to form defects known as A-centers in silicon. We calculate the formation energy of the defect with respect to the Fermi energy for all possible charge states. It is found that the neutral and doubly negatively charged A-centers dominate. The findings are analyzed in terms of the density of states and discussed in view of previous experimental and theoretical studies.

  7. A-centers in silicon studied with hybrid density functional theory

    KAUST Repository

    Wang, Hao

    2013-07-29

    Density functional theory employing hybrid functional is used to gain fundamental insight into the interaction of vacancies with oxygen interstitials to form defects known as A-centers in silicon. We calculate the formation energy of the defect with respect to the Fermi energy for all possible charge states. It is found that the neutral and doubly negatively charged A-centers dominate. The findings are analyzed in terms of the density of states and discussed in view of previous experimental and theoretical studies.

  8. Ab‐initio study of germanium di-interstitial using a hybrid functional (HSE)

    Energy Technology Data Exchange (ETDEWEB)

    Igumbor, E., E-mail: elgumuk@gmail.com [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Department of Mathematics and Physical Sciences, Samuel Adegboyega University, Km 1 Ogwa/Ehor Rd, Ogwa, Edo State (Nigeria); Ouma, C.N.M.; Webb, G. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Meyer, W.E., E-mail: wmeyer@up.ac.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)

    2016-01-01

    In this work, we present ab‐initio calculation results of Ge di-interstitials (I{sub 2(Ge)}) in the framework of the density functional theory (DFT) using the Heyd, Scuseria, and Ernzerhof (HSE) hybrid functional. The formation energy, transition levels and minimum energy configurations were obtained for I{sub 2(Ge)} −2, −1, 0, +1 and +2 charge states. The calculated formation energies show that for all charge states of I{sub 2(Ge)}, the double tetrahedral (T) configuration formed the most stable defect with a binding energy of 1.24 eV in the neutral state. We found the (+2/+1) charge state transition level for the T lying below the conduction band minimum and (+2/+1) for the split[110]-tetrahedral configuration lying deep at 0.41 eV above the valence band maximum. The di-interstitials in Ge exhibited the properties of both shallow and deep donor levels at (+2/+1) within the band gap and depending on the configurations. I{sub 2(Ge)} gave rise to negative-U, with effective-U values of −0.61 and −1.6 eV in different configurations. We have compared our results with calculations of di-interstitials in silicon and available experimental data.

  9. Appropriate description of intermolecular interactions in the methane hydrates: an assessment of DFT methods.

    Science.gov (United States)

    Liu, Yuan; Zhao, Jijun; Li, Fengyu; Chen, Zhongfang

    2013-01-15

    Accurate description of hydrogen-bonding energies between water molecules and van der Waals interactions between guest molecules and host water cages is crucial for study of methane hydrates (MHs). Using high-level ab initio MP2 and CCSD(T) results as the reference, we carefully assessed the performance of a variety of exchange-correlation functionals and various basis sets in describing the noncovalent interactions in MH. The functionals under investigation include the conventional GGA, meta-GGA, and hybrid functionals (PBE, PW91, TPSS, TPSSh, B3LYP, and X3LYP), long-range corrected functionals (ωB97X, ωB97, LC-ωPBE, CAM-B3LYP, and LC-TPSS), the newly developed Minnesota class functionals (M06-L, M06-HF, M06, and M06-2X), and the dispersion-corrected density functional theory (DFT) (DFT-D) methods (B97-D, ωB97X-D, PBE-TS, PBE-Grimme, and PW91-OBS). We found that the conventional functionals are not suitable for MH, notably, the widely used B3LYP functional even predicts repulsive interaction between CH(4) and (H(2)O)(6) cluster. M06-2X is the best among the M06-Class functionals. The ωB97X-D outperforms the other DFT-D methods and is recommended for accurate first-principles calculations of MH. B97-D is also acceptable as a compromise of computational cost and precision. Considering both accuracy and efficiency, B97-D, ωB97X-D, and M06-2X functional with 6-311++G(2d,2p) basis set without basis set superposition error (BSSE) correction are recommended. Though a fairly large basis set (e.g., aug-cc-pVTZ) and BSSE correction are necessary for a reliable MP2 calculation, DFT methods are less sensitive to the basis set and BSSE correction if the basis set is sufficient (e.g., 6-311++G(2d,2p)). These assessments provide useful guidance for choosing appropriate methodology of first-principles simulation of MH and related systems. © 2012 Wiley Periodicals, Inc. Copyright © 2012 Wiley Periodicals, Inc.

  10. 2D/0D graphene hybrids for visible-blind flexible UV photodetectors.

    Science.gov (United States)

    Tetsuka, Hiroyuki

    2017-07-17

    Nitrogen-functionalized graphene quantum dots (NGQDs) are attractive building blocks for optoelectronic devices because of their exceptional tunable optical absorption and fluorescence properties. Here, we developed a high-performance flexible NGQD/graphene field-effect transistor (NGQD@GFET) hybrid ultraviolet (UV) photodetector, using dimethylamine-functionalized GQDs (NMe 2 -GQDs) with a large bandgap of ca. 3.3 eV. The NMe 2 -GQD@GFET photodetector exhibits high photoresponsivity and detectivity of ca. 1.5 × 10 4  A W -1 and ca. 5.5 × 10 11 Jones, respectively, in the deep-UV region as short as 255 nm without application of a backgate voltage. The feasibility of these flexible UV photodetectors for practical application in flame alarms is also demonstrated.

  11. A Dynamic Multistage Hybrid Swarm Intelligence Optimization Algorithm for Function Optimization

    Directory of Open Access Journals (Sweden)

    Daqing Wu

    2012-01-01

    Full Text Available A novel dynamic multistage hybrid swarm intelligence optimization algorithm is introduced, which is abbreviated as DM-PSO-ABC. The DM-PSO-ABC combined the exploration capabilities of the dynamic multiswarm particle swarm optimizer (PSO and the stochastic exploitation of the cooperative artificial bee colony algorithm (CABC for solving the function optimization. In the proposed hybrid algorithm, the whole process is divided into three stages. In the first stage, a dynamic multiswarm PSO is constructed to maintain the population diversity. In the second stage, the parallel, positive feedback of CABC was implemented in each small swarm. In the third stage, we make use of the particle swarm optimization global model, which has a faster convergence speed to enhance the global convergence in solving the whole problem. To verify the effectiveness and efficiency of the proposed hybrid algorithm, various scale benchmark problems are tested to demonstrate the potential of the proposed multistage hybrid swarm intelligence optimization algorithm. The results show that DM-PSO-ABC is better in the search precision, and convergence property and has strong ability to escape from the local suboptima when compared with several other peer algorithms.

  12. Benchmark Study of the Structural and Thermochemical Properties of a Dihydroazulene/Vinylheptafulvene Photoswitch

    DEFF Research Database (Denmark)

    Koerstz, Mads; Elm, Jonas; Mikkelsen, Kurt Valentin

    2017-01-01

    We investigate the performance of four different density functional theory (DFT) functionals (M06-2X, ωB97X-D, PBE0, and B3LYP-D3BJ) for calculating the structural and thermochemical properties of the dihydroazulene/vinylheptafulvene photoswitch (DHA/VHF). We find that all the tested DFT......, indicating that the largest source of error when calculating storage free energies originates from errors in the calculated single point energies. It was found that ωB97X-D and M06-2X performed decently for predicting storage energies. While B3LYP-D3BJ and PBE0 generally underestimated the storage energy...

  13. Relativistic Adiabatic Time-Dependent Density Functional Theory Using Hybrid Functionals and Noncollinear Spin Magnetization

    DEFF Research Database (Denmark)

    Bast, Radovan; Jensen, Hans Jørgen Aagaard; Saue, Trond

    2009-01-01

    into reduction of algebra from quaternion to complex or real. For hybrid GGAs with noncollinear spin magnetization we derive a new computationally advantageous equation for the full second variational derivatives of such exchange-correlation functionals. We apply our implementation to calculations on the ns2...... → ns1np1 excitation energies in the Zn, Cd, and Hg atoms (n = 4-6) and (vertical) excitation energies of UO2+ 2 ; and we test the performance of various functionals by comparison with experimental data (group 12 atoms) or higher-level computational results (UO2+2 ). The results indicate...

  14. Dependence of Excited State Potential Energy Surfaces on the Spatial Overlap of the Kohn-Sham Orbitals and the Amount of Nonlocal Hartree-Fock Exchange in Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Plötner, Jürgen; Tozer, David J; Dreuw, Andreas

    2010-08-10

    Time-dependent density functional theory (TDDFT) with standard GGA or hybrid exchange-correlation functionals is not capable of describing the potential energy surface of the S1 state of Pigment Yellow 101 correctly; an additional local minimum is observed at a twisted geometry with substantial charge transfer (CT) character. To investigate the influence of nonlocal exact orbital (Hartree-Fock) exchange on the shape of the potential energy surface of the S1 state in detail, it has been computed along the twisting coordinate employing the standard BP86, B3LYP, and BHLYP xc-functionals as well as the long-range separated (LRS) exchange-correlation (xc)-functionals LC-BOP, ωB97X, ωPBE, and CAM-B3LYP and compared to RI-CC2 benchmark results. Additionally, a recently suggested Λ-parameter has been employed that measures the amount of CT in an excited state by calculating the spatial overlap of the occupied and virtual molecular orbitals involved in the transition. Here, the error in the calculated S1 potential energy curves at BP86, B3LYP, and BHLYP can be clearly related to the Λ-parameter, i.e., to the extent of charge transfer. Additionally, it is demonstrated that the CT problem is largely alleviated when the BHLYP xc-functional is employed, although it still exhibits a weak tendency to underestimate the energy of CT states. The situation improves drastically when LRS-functionals are employed within TDDFT excited state calculations. All tested LRS-functionals give qualitatively the correct potential energy curves of the energetically lowest excited states of P. Y. 101 along the twisting coordinate. While LC-BOP and ωB97X overcorrect the CT problem and now tend to give too large excitation energies compared to other non-CT states, ωPBE and CAM-B3LYP are in excellent agreement with the RI-CC2 results, with respect to both the correct shape of the potential energy curve as well as the absolute values of the calculated excitation energies.

  15. Enzymatic functionalization of cork surface with antimicrobial hybrid biopolymer/silver nanoparticles.

    Science.gov (United States)

    Francesko, Antonio; Blandón, Lucas; Vázquez, Mario; Petkova, Petya; Morató, Jordi; Pfeifer, Annett; Heinze, Thomas; Mendoza, Ernest; Tzanov, Tzanko

    2015-05-13

    Laccase-assisted assembling of hybrid biopolymer-silver nanoparticles and cork matrices into an antimicrobial material with potential for water remediation is herein described. Amino-functional biopolymers were first used as doping agents to stabilize concentrated colloidal dispersions of silver nanoparticles (AgNP), additionally providing the particles with functionalities for covalent immobilization onto cork to impart a durable antibacterial effect. The solvent-free AgNP synthesis by chemical reduction was carried out in the presence of chitosan (CS) or 6-deoxy-6-(ω-aminoethyl) aminocellulose (AC), leading to simultaneous AgNP biofunctionalization. This approach resulted in concentrated hybrid NP dispersion stable to aggregation and with hydrodynamic radius of particles of about 250 nm. Moreover, laccase enabled coupling between the phenolic groups in cork and amino moieties in the biopolymer-doped AgNP for permanent modification of the material. The antibacterial efficiency of the functionalized cork matrices, aimed as adsorbents for wastewater treatment, was evaluated against Escherichia coli and Staphylococcus aureus during 5 days in conditions mimicking those in constructed wetlands. Both intrinsically antimicrobial CS and AC contributed to the bactericidal effect of the enzymatically grafted on cork AgNP. In contrast, unmodified AgNP were easily washed off from the material, confirming that the biopolymers potentiated a durable antibacterial functionalization of the cork matrices.

  16. Hybrid artificial bee colony algorithm for parameter optimization of five-parameter bidirectional reflectance distribution function model.

    Science.gov (United States)

    Wang, Qianqian; Zhao, Jing; Gong, Yong; Hao, Qun; Peng, Zhong

    2017-11-20

    A hybrid artificial bee colony (ABC) algorithm inspired by the best-so-far solution and bacterial chemotaxis was introduced to optimize the parameters of the five-parameter bidirectional reflectance distribution function (BRDF) model. To verify the performance of the hybrid ABC algorithm, we measured BRDF of three kinds of samples and simulated the undetermined parameters of the five-parameter BRDF model using the hybrid ABC algorithm and the genetic algorithm, respectively. The experimental results demonstrate that the hybrid ABC algorithm outperforms the genetic algorithm in convergence speed, accuracy, and time efficiency under the same conditions.

  17. Thermochemical Storage of Middle Temperature Wasted Heat by Functionalized C/Mg(OH2 Hybrid Materials

    Directory of Open Access Journals (Sweden)

    Emanuela Mastronardo

    2017-01-01

    Full Text Available For the thermochemical performance implementation of Mg(OH2 as a heat storage medium, several hybrid materials have been investigated. For this study, high-performance hybrid materials have been developed by exploiting the authors’ previous findings. Expanded graphite (EG/carbon nanotubes (CNTs-Mg(OH2 hybrid materials have been prepared through Mg(OH2 deposition-precipitation over functionalized, i.e., oxidized, or un-functionalized EG or CNTs. The heat storage performances of the carbon-based hybrid materials have been investigated through a laboratory-scale experimental simulation of the heat storage/release cycles, carried out by a thermogravimetric apparatus. This study offers a critical evaluation of the thermochemical performances of developed materials through their comparison in terms of heat storage and output capacities per mass and volume unit. It was demonstrated that both EG and CNTs improves the thermochemical performances of the storage medium in terms of reaction rate and conversion with respect to pure Mg(OH2. With functionalized EG/CNTs-Mg(OH2, (i the potential heat storage and output capacities per mass unit of Mg(OH2 have been completely exploited; and (ii higher heat storage and output capacities per volume unit were obtained. That means, for technological applications, as smaller volume at equal stored/released heat.

  18. 0.4-1.2 GHz hybrid Al-CFRP open-boundary quad-ridge horn

    DEFF Research Database (Denmark)

    Kim, Oleksiy S.; Pivnenko, Sergey; Breinbjerg, Olav

    2011-01-01

    We present a 0.4-1.2 GHz open-boundary quad-ridge horn to be used as a wide-band probe at the DTU-ESA Spherical Near-Field Antenna Test Facility at the Technical University of Denmark (DTU). Due to adopted hybrid Al-CFRP fabrication technology, the weight of the probe is reduced by a factor of 2...

  19. ZnO nanorods/ZnS.(1,6-hexanediamine)0.5 hybrid nanoplates hierarchical heteroarchitecture with improved electrochemical catalytic properties for hydrazine

    Science.gov (United States)

    Wu, Zhengcui; Wu, Yaqin; Pei, Tonghui; Wang, Huan; Geng, Baoyou

    2014-02-01

    Novel hierarchical heteronanostructures of ZnO nanorods/ZnS.(HDA)0.5 (HDA = 1,6-hexanediamine) hybrid nanoplates on a zinc substrate are successfully synthesized on a large scale by combining hydrothermal growth (for ZnO nanorods) and liquid chemical conversion (for ZnS.(HDA)0.5 nanoplates) techniques. The formation of ZnS.(HDA)0.5 hybrid nanoplates branches takes advantage of the preferential binding of 1,6-hexanediamine on specific facets of ZnS, which makes the thickening rate much lower than the lateral growth rate. The ZnS.(HDA)0.5 hybrid nanoplates have a layered structure with 1,6-hexanediamine inserted into interlayers of wurtzite ZnS through the bonding of nitrogen. The number density and thickness of the secondary ZnS.(HDA)0.5 nanoplates can be conveniently engineered by variation of the sulfur source and straightforward adjustment of reactant concentrations such as 1,6-hexanediamine and the sulfur source. The fabricated ZnO/ZnS.(HDA)0.5 heteronanostructures show improved electrochemical catalytic properties for hydrazine compared with the primary ZnO nanorods. Due to its simplicity and efficiency, this approach could be similarly used to fabricate varieties of hybrid heterostructures made of materials with an intrinsic large lattice mismatch.Novel hierarchical heteronanostructures of ZnO nanorods/ZnS.(HDA)0.5 (HDA = 1,6-hexanediamine) hybrid nanoplates on a zinc substrate are successfully synthesized on a large scale by combining hydrothermal growth (for ZnO nanorods) and liquid chemical conversion (for ZnS.(HDA)0.5 nanoplates) techniques. The formation of ZnS.(HDA)0.5 hybrid nanoplates branches takes advantage of the preferential binding of 1,6-hexanediamine on specific facets of ZnS, which makes the thickening rate much lower than the lateral growth rate. The ZnS.(HDA)0.5 hybrid nanoplates have a layered structure with 1,6-hexanediamine inserted into interlayers of wurtzite ZnS through the bonding of nitrogen. The number density and thickness of the

  20. Hybrid functional band gap calculation of SnO6 containing perovskites and their derived structures

    International Nuclear Information System (INIS)

    Lee, Hyewon; Cheong, S.W.; Kim, Bog G.

    2015-01-01

    We have studied the properties of SnO 6 octahedra-containing perovskites and their derived structures using ab initio calculations with different density functionals. In order to predict the correct band gap of the materials, we have used B3LYP hybrid density functional, and the results of B3LYP were compared with those obtained using the local density approximation and generalized gradient approximation data. The calculations have been conducted for the orthorhombic ground state of the SnO 6 containing perovskites. We also have expended the hybrid density functional calculation to the ASnO 3 /A'SnO 3 system with different cation orderings. We propose an empirical relationship between the tolerance factor and the band gap of SnO 6 containing oxide materials based on first principles calculation. - Graphical abstract: (a) Structure of ASnO 3 for orthorhombic ground state. The green ball is A (Ba, Sr, Ca) cation and the small (red) ball on edge is oxygen. SnO 6 octahedrons are plotted as polyhedron. (b) Band gap of ASnO 3 as a function of the tolerance factor for different density functionals. The experimental values of the band gap are marked as green pentagons. (c) ASnO 3 /A'SnO 3 superlattices with two types cation arrangement: [001] layered structure and [111] rocksalt structure, respectively. (d) B3LYP hybrid functional band gaps of ASnO 3 , [001] ordered superlattices, and [111] ordered superlattices of ASnO 3 /A'SnO 3 as a function of the effective tolerance factor. Note the empirical linear relationship between the band gap and effective tolerance factor. - Highlights: • We report the hybrid functional band gap calculation of ASnO 3 and ASnO 3 /A'SnO 3 . • The band gap of ASnO 3 using B3LYP functional reproduces the experimental value. • We propose the linear relationship between the tolerance factor and the band gap

  1. Functionalized hybrid nanofibers to mimic native ECM for tissue engineering applications

    International Nuclear Information System (INIS)

    Karuppuswamy, Priyadharsini; Venugopal, Jayarama Reddy; Navaneethan, Balchandar; Laiva, Ashang Luwang; Sridhar, Sreepathy; Ramakrishna, Seeram

    2014-01-01

    Highlights: • Functionalized hybrid polymer mats fabricated for tissue engineering. • Hybrid polymer mats showed high surface area, high porosity and good wettability. • Incorporation of natural polymers modified the properties of nanofiber mats more biologically favorable for biomedical applications. - Abstract: Nanotechnology being one of the most promising technologies today shows an extremely huge potential in the field of tissue engineering to mimic the porous topography of natural extracellular matrix (ECM). Natural polymers are incorporated into the synthetic polymers to fabricate functionalized hybrid nanofibrous scaffolds, which improve cell and tissue compatibility. The present study identified the biopolymers – aloe vera, silk fibroin and curcumin incorporated into polycaprolactone (PCL) as suitable substrates for tissue engineering. Different combinations of PCL with natural polymers – PCL/aloe vera, PCL/silk fibroin, PCL/aloe vera/silk fibroin, PCL/aloe vera/silk fibroin/curcumin were electrospun into nanofibrous scaffolds. The fabricated two dimensional nanofibrous scaffolds showed high surface area, appropriate mechanical properties, hydrophilicity and porosity, required for the regeneration of diseased tissues. The nanofibrous scaffolds were characterized by Scanning electron microscope (SEM), porometry, Instron tensile tester, VCA optima contact angle measurement and FTIR to analyze the fiber diameter and morphology, porosity and pore size distribution, mechanical strength, wettability, chemical bonds and functional groups, respectively. The average fiber diameter of obtained fibers ranged from 250 nm to 350 nm and the tensile strength of PCL scaffolds at 4.49 MPa increased upto 8.3 MPa for PCL/silk fibroin scaffolds. Hydrophobicity of PCL decreased with the incorporation of natural polymers, especially for PCL/aloe vera scaffolds. The properties of as-spun nanofiber scaffolds showed their potential as promising scaffold materials in

  2. Functionalized hybrid nanofibers to mimic native ECM for tissue engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Karuppuswamy, Priyadharsini [Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, Singapore (Singapore); Department Physics and Nanotechnology, SRM University, Kattankulathur, Chennai (India); Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Venugopal, Jayarama Reddy, E-mail: nnijrv@nus.edu.sg [Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, Singapore (Singapore); Navaneethan, Balchandar [Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, Singapore (Singapore); Department Physics and Nanotechnology, SRM University, Kattankulathur, Chennai (India); Laiva, Ashang Luwang; Sridhar, Sreepathy; Ramakrishna, Seeram [Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, Faculty of Engineering, National University of Singapore, Singapore (Singapore)

    2014-12-15

    Highlights: • Functionalized hybrid polymer mats fabricated for tissue engineering. • Hybrid polymer mats showed high surface area, high porosity and good wettability. • Incorporation of natural polymers modified the properties of nanofiber mats more biologically favorable for biomedical applications. - Abstract: Nanotechnology being one of the most promising technologies today shows an extremely huge potential in the field of tissue engineering to mimic the porous topography of natural extracellular matrix (ECM). Natural polymers are incorporated into the synthetic polymers to fabricate functionalized hybrid nanofibrous scaffolds, which improve cell and tissue compatibility. The present study identified the biopolymers – aloe vera, silk fibroin and curcumin incorporated into polycaprolactone (PCL) as suitable substrates for tissue engineering. Different combinations of PCL with natural polymers – PCL/aloe vera, PCL/silk fibroin, PCL/aloe vera/silk fibroin, PCL/aloe vera/silk fibroin/curcumin were electrospun into nanofibrous scaffolds. The fabricated two dimensional nanofibrous scaffolds showed high surface area, appropriate mechanical properties, hydrophilicity and porosity, required for the regeneration of diseased tissues. The nanofibrous scaffolds were characterized by Scanning electron microscope (SEM), porometry, Instron tensile tester, VCA optima contact angle measurement and FTIR to analyze the fiber diameter and morphology, porosity and pore size distribution, mechanical strength, wettability, chemical bonds and functional groups, respectively. The average fiber diameter of obtained fibers ranged from 250 nm to 350 nm and the tensile strength of PCL scaffolds at 4.49 MPa increased upto 8.3 MPa for PCL/silk fibroin scaffolds. Hydrophobicity of PCL decreased with the incorporation of natural polymers, especially for PCL/aloe vera scaffolds. The properties of as-spun nanofiber scaffolds showed their potential as promising scaffold materials in

  3. Immobilization of carbon nanotubes on functionalized graphene film grown by chemical vapor deposition and characterization of the hybrid material

    Directory of Open Access Journals (Sweden)

    Prashanta Dhoj Adhikari

    2014-01-01

    Full Text Available We report the surface functionalization of graphene films grown by chemical vapor deposition and fabrication of a hybrid material combining multi-walled carbon nanotubes and graphene (CNT–G. Amine-terminated self-assembled monolayers were prepared on graphene by the UV-modification of oxidized groups introduced onto the film surface. Amine-termination led to effective interaction with functionalized CNTs to assemble a CNT–G hybrid through covalent bonding. Characterization clearly showed no defects of the graphene film after the immobilization reaction with CNT. In addition, the hybrid graphene material revealed a distinctive CNT–G structure and p–n type electrical properties. The introduction of functional groups on the graphene film surface and fabrication of CNT–G hybrids with the present technique could provide an efficient, novel route to device fabrication.

  4. Long-range-corrected Rung 3.5 density functional approximations

    Science.gov (United States)

    Janesko, Benjamin G.; Proynov, Emil; Scalmani, Giovanni; Frisch, Michael J.

    2018-03-01

    Rung 3.5 functionals are a new class of approximations for density functional theory. They provide a flexible intermediate between exact (Hartree-Fock, HF) exchange and semilocal approximations for exchange. Existing Rung 3.5 functionals inherit semilocal functionals' limitations in atomic cores and density tails. Here we address those limitations using range-separated admixture of HF exchange. We present three new functionals. LRC-ωΠLDA combines long-range HF exchange with short-range Rung 3.5 ΠLDA exchange. SLC-ΠLDA combines short- and long-range HF exchange with middle-range ΠLDA exchange. LRC-ωΠLDA-AC incorporates a combination of HF, semilocal, and Rung 3.5 exchange in the short range, based on an adiabatic connection. We test these in a new Rung 3.5 implementation including up to analytic fourth derivatives. LRC-ωΠLDA and SLC-ΠLDA improve atomization energies and reaction barriers by a factor of 8 compared to the full-range ΠLDA. LRC-ωΠLDA-AC brings further improvement approaching the accuracy of standard long-range corrected schemes LC-ωPBE and SLC-PBE. The new functionals yield highest occupied orbital energies closer to experimental ionization potentials and describe correctly the weak charge-transfer complex of ethylene and dichlorine and the hole-spin distribution created by an Al defect in quartz. This study provides a framework for more flexible range-separated Rung 3.5 approximations.

  5. Functionalized carbon nanotube based hybrid electrochemical capacitors using neutral bromide redox-active electrolyte for enhancing energy density

    Science.gov (United States)

    Tang, Xiaohui; Lui, Yu Hui; Chen, Bolin; Hu, Shan

    2017-06-01

    A hybrid electrochemical capacitor (EC) with enhanced energy density is realized by integrating functionalized carbon nanotube (FCNT) electrodes with redox-active electrolyte that has a neutral pH value (1 M Na2SO4 and 0.5 M KBr mixed aqueous solution). The negative electrode shows an electric double layer capacitor-type behavior. On the positive electrode, highly reversible Br-/Br3- redox reactions take place, presenting a battery-type behavior, which contributes to increase the capacitance of the hybrid cell. The voltage window of the whole cell is extended up to 1.5 V because of the high over-potentials of oxygen and hydrogen evolution reactions in the neutral electrolyte. Compared with raw CNT, the FCNT has better wettability in the aqueous electrolyte and contributes to increase the electric double layer capacitance of the cell. As a result, the maximum energy density of 28.3 Wh kg-1 is obtained from the hybrid EC at 0.5 A g-1 without sacrificing its power density, which is around 4 times larger than that of the electrical double layer capacitor constructed by FCNT electrodes and 1 M Na2SO4 electrolyte. Moreover, the discharge capacity retained 86.3% of its initial performance after 10000 cycles of galvanostatic charge and discharge test (10 A/g), suggesting its long life cycle even at high current loading.

  6. Hybride textuelle Strukturen und hybride textuelle Einheiten. Ein Beitrag zur Theorie der Wörterbuchform

    Directory of Open Access Journals (Sweden)

    Herbert Ernst Wiegand

    2011-10-01

    Textsegmentklassen aufweisen (vgl. die Stichwörter.

    Stichwörter: ANGABERELATION, ELEMENTENHETEROGENE TRÄGERMENGE, FUNKTIONALER ANGABEZUSATZ, FUNKTIONAL-POSITIONALE SEGMENTATION, HIERARCHISCHE ARCHITEKTONISCH ANGEREICHERTE ARTIKELMIKROSTRUKTUR, HIERARCHISCHE HYBRIDE ANGABENKONSTITUENTENSTRUKTUR MIT GLOSSATBEDINGTER TEILSTRUKTUR, HIERARCHISCHE HYBRIDE ANGABENSTRUKTUR, HIERARCHISCHE HYBRIDE ARTIKELKONSTITUENTENSTRUKTUR, HIERARCHISCHE HYBRIDE ARTIKELMIKROSTRUKTUR, HIERARCHISCHE HYBRIDE EXHAUSTIVE ANGABENSTRUKTUR, HIERARCHISCHE HYBRIDE GLOSSATBEDINGTE ANGABESTRUKTUR, HIERARCHISCHE HYBRIDE FLACHE DOPPELGLOSSATBEDINGTE ANGABESTRUKTUR, HIERARCHISCHE HYBRIDE MINIMIERTE GLOSSATBEDINGTE ANGABESTRUKTUR, HIERARCHISCHE HYBRIDE TEXTKONSTITUENTENSTRUKTUR, HIERARCHISCHE HYBRIDE TIEFE DOPPELGLOSSATBEDINGTE ANGABESTRUKTUR, HIERARCHISCHE REINE TEXTKONSTITUENTENSTRUKTUR, HYBRIDE VERWEISKENNZEICHNUNG, NICHTFUNKTIONALE-POSITIONALE SEGMENTATION, ORDNUNGSRELATION, SEGMENTATIVE ISOLIERUNG, VERTIKALE ANGABEARCHITEKTUR

     

    ABSTRACT: Hybrid textual structures and hybrid textual units. A contribution to the theory of dictionary structures. In this contribution, the formation, presentation and performance of hybrid textual structures that display accessible entries are discussed by using examples from dictionary articles. The features of hybrid textual units are also explained. A dictionary article in a printed dictionary always displays both a hierarchical pure and a hierarchical hybrid text constituent structure, when it contains at least one functional item addition, e.g. an upward- or downward- or an internally-expanded one. Because functional item additions are text segments with an item function but without text constituent status, they are enabled by means of non-functional segmentation, so that both functional and non-functional text segments prevail. During the formation of structures they then enter the structure-carrying set so that the structurecarrying set of all hybrid

  7. Performance of various density functionals for the hydrogen bonds in DNA base pairs

    NARCIS (Netherlands)

    van der Wijst, T.; Fonseca Guerra, C.; Swart, M.; Bickelhaupt, F.M.

    2006-01-01

    We have investigated the performance of seven popular density functionals (B3LYP, BLYP, BP86, mPW, OPBE, PBE, PW91) for describing the geometry and stability of the hydrogen bonds in DNA base pairs. For the gas-phase situation, the hydrogen-bond lengths and strengths in the DNA pairs have been

  8. G-centers in irradiated silicon revisited: A screened hybrid density functional theory approach

    KAUST Repository

    Wang, H.; Chroneos, A.; Londos, C. A.; Sgourou, E. N.; Schwingenschlö gl, Udo

    2014-01-01

    Electronic structure calculations employing screened hybrid density functional theory are used to gain fundamental insight into the interaction of carbon interstitial (Ci) and substitutional (Cs) atoms forming the CiCs defect known as G

  9. First principles and Debye model study of the thermodynamic, electronic and optical properties of MgO under high-temperature and pressure

    Science.gov (United States)

    Miao, Yurun; Li, Huayang; Wang, Hongjuan; He, Kaihua; Wang, Qingbo

    2018-02-01

    First principles and quasi-harmonic Debye model have been used to study the thermodynamic properties, enthalpies, electronic and optical properties of MgO up to the core-mantle boundary (CMB) condition (137 GPa and 3700 K). Thermodynamic properties calculation includes thermal expansion coefficient and capacity, which have been studied up to the CMB pressure (137 GPa) and temperature (3700 K) by the Debye model with generalized gradient approximation (GGA) and local-density approximation (LDA). First principles with hybrid functional method (PBE0) has been used to calculate the electronic and optical properties under pressure up to 137 GPa and 0 K. Our results show the Debye model with LDA and first principles with PBE0 can provide accurate thermodynamic properties, enthalpies, electronic and optical properties. Calculated enthalpies show that MgO keep NaCl (B1) structure up to 137 GPa. And MgO is a direct bandgap insulator with a 7.23 eV calculated bandgap. The bandgap increased with increasing pressure, which will induce a blue shift of optical properties. We also calculated the density of states (DOS) and discussed the relation between DOS and band, optical properties. Equations were used to fit the relations between pressure and bandgaps, absorption coefficient (α(ω)) of MgO. The equations can be used to evaluate pressure after careful calibration. Our calculations can not only be used to identify some geological processes, but also offer a reference to the applications of MgO in the future.

  10. How well can DFT reproduce key interactions in Ziegler-Natta systems?

    KAUST Repository

    Correa, Andrea

    2013-08-08

    The performance of density functional theory in reproducing some of the main interactions occurring in MgCl2-supported Ziegler-Natta catalytic systems is assessed. Eight model systems, representatives of key interactions occurring in Ziegler-Natta catalysts, are selected. Fifteen density functionals are tested in combination with two different basis sets, namely, TZVP and cc-pVTZ. As a general result, we found that the best performances are achieved by the PBEh1PBE hybrid generalized gradient approximation (GGA) functional, but also the cheaper PBEh GGA functional gives rather good results. The failure of the popular B3LYP and BP86 functionals is noticeable. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. First-principles calculations on double-walled inorganic nanotubes with hexagonal chiralities

    International Nuclear Information System (INIS)

    Zhukovskii, Yuri F; Evarestov, Robert A; Bandura, Andrei V; Losev, Maxim V

    2011-01-01

    The two sets of commensurate double-walled boron nitride and titania hexagonally-structured nanotubes (DW BN and TiO 2 NTs) possessing either armchair- or zigzag-type chiralities have been considered, i.e., (n 1 ,n 1 )-(n 2 ,n 2 ) or (n 1 ,0)-(n 2 ,0), respectively. For symmetry analysis of these nanotubes, the line symmetry groups for one-periodic (1D) nanostructures with rotohelical symmetry have been applied. To analyze the structural and electronic properties of hexagonal DW NTs, a series of large-scale ab initio DFT-LCAO calculations have been performed using the hybrid Hartree-Fock/Kohn-Sham exchange-correlation functional PBE0 (as implemented in CRYSTAL-09 code). To establish the optimal inter-shell distances within DW NTs corresponding to the minima of calculated total energy, the chiral indices n 1 and n 2 of the constituent single-walled (SW) nanotubes have been successively varied.

  12. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    International Nuclear Information System (INIS)

    Krukiewicz, Katarzyna; Herman, Artur P.; Turczyn, Roman; Szymańska, Katarzyna; Koziol, Krzysztof K.K.; Boncel, Sławomir; Zak, Jerzy K.

    2014-01-01

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains

  13. A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Krukiewicz, Katarzyna, E-mail: katarzyna.krukiewicz@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Herman, Artur P., E-mail: artur.herman@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Turczyn, Roman, E-mail: roman.turczyn@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Szymańska, Katarzyna, E-mail: katarzyna.szymanska@polsl.pl [Department of Chemical and Process Engineering, Silesian University of Technology, Strzody 7, 44-100 Gliwice (Poland); Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Boncel, Sławomir, E-mail: slawomir.boncel@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Zak, Jerzy K., E-mail: jerzy.zak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland)

    2014-10-30

    Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains.

  14. Benchmarking DFT and semi-empirical methods for a reliable and cost-efficient computational screening of benzofulvene derivatives as donor materials for small-molecule organic solar cells.

    Science.gov (United States)

    Tortorella, Sara; Talamo, Maurizio Mastropasqua; Cardone, Antonio; Pastore, Mariachiara; De Angelis, Filippo

    2016-02-24

    A systematic computational investigation on the optical properties of a group of novel benzofulvene derivatives (Martinelli 2014 Org. Lett. 16 3424-7), proposed as possible donor materials in small molecule organic photovoltaic (smOPV) devices, is presented. A benchmark evaluation against experimental results on the accuracy of different exchange and correlation functionals and semi-empirical methods in predicting both reliable ground state equilibrium geometries and electronic absorption spectra is carried out. The benchmark of the geometry optimization level indicated that the best agreement with x-ray data is achieved by using the B3LYP functional. Concerning the optical gap prediction, we found that, among the employed functionals, MPW1K provides the most accurate excitation energies over the entire set of benzofulvenes. Similarly reliable results were also obtained for range-separated hybrid functionals (CAM-B3LYP and wB97XD) and for global hybrid methods incorporating a large amount of non-local exchange (M06-2X and M06-HF). Density functional theory (DFT) hybrids with a moderate (about 20-30%) extent of Hartree-Fock exchange (HFexc) (PBE0, B3LYP and M06) were also found to deliver HOMO-LUMO energy gaps which compare well with the experimental absorption maxima, thus representing a valuable alternative for a prompt and predictive estimation of the optical gap. The possibility of using completely semi-empirical approaches (AM1/ZINDO) is also discussed.

  15. Benchmarking DFT and semi-empirical methods for a reliable and cost-efficient computational screening of benzofulvene derivatives as donor materials for small-molecule organic solar cells

    International Nuclear Information System (INIS)

    Tortorella, Sara; Talamo, Maurizio Mastropasqua; Cardone, Antonio; Pastore, Mariachiara; De Angelis, Filippo

    2016-01-01

    A systematic computational investigation on the optical properties of a group of novel benzofulvene derivatives (Martinelli 2014 Org. Lett. 16 3424–7), proposed as possible donor materials in small molecule organic photovoltaic (smOPV) devices, is presented. A benchmark evaluation against experimental results on the accuracy of different exchange and correlation functionals and semi-empirical methods in predicting both reliable ground state equilibrium geometries and electronic absorption spectra is carried out. The benchmark of the geometry optimization level indicated that the best agreement with x-ray data is achieved by using the B3LYP functional. Concerning the optical gap prediction, we found that, among the employed functionals, MPW1K provides the most accurate excitation energies over the entire set of benzofulvenes. Similarly reliable results were also obtained for range-separated hybrid functionals (CAM-B3LYP and wB97XD) and for global hybrid methods incorporating a large amount of non-local exchange (M06-2X and M06-HF). Density functional theory (DFT) hybrids with a moderate (about 20–30%) extent of Hartree–Fock exchange (HFexc) (PBE0, B3LYP and M06) were also found to deliver HOMO–LUMO energy gaps which compare well with the experimental absorption maxima, thus representing a valuable alternative for a prompt and predictive estimation of the optical gap. The possibility of using completely semi-empirical approaches (AM1/ZINDO) is also discussed. (paper)

  16. ZnO nanorods/ZnS·(1,6-hexanediamine)(0.5) hybrid nanoplates hierarchical heteroarchitecture with improved electrochemical catalytic properties for hydrazine.

    Science.gov (United States)

    Wu, Zhengcui; Wu, Yaqin; Pei, Tonghui; Wang, Huan; Geng, Baoyou

    2014-03-07

    Novel hierarchical heteronanostructures of ZnO nanorods/ZnS·(HDA)0.5 (HDA = 1,6-hexanediamine) hybrid nanoplates on a zinc substrate are successfully synthesized on a large scale by combining hydrothermal growth (for ZnO nanorods) and liquid chemical conversion (for ZnS·(HDA)0.5 nanoplates) techniques. The formation of ZnS·(HDA)0.5 hybrid nanoplates branches takes advantage of the preferential binding of 1,6-hexanediamine on specific facets of ZnS, which makes the thickening rate much lower than the lateral growth rate. The ZnS·(HDA)0.5 hybrid nanoplates have a layered structure with 1,6-hexanediamine inserted into interlayers of wurtzite ZnS through the bonding of nitrogen. The number density and thickness of the secondary ZnS·(HDA)0.5 nanoplates can be conveniently engineered by variation of the sulfur source and straightforward adjustment of reactant concentrations such as 1,6-hexanediamine and the sulfur source. The fabricated ZnO/ZnS·(HDA)0.5 heteronanostructures show improved electrochemical catalytic properties for hydrazine compared with the primary ZnO nanorods. Due to its simplicity and efficiency, this approach could be similarly used to fabricate varieties of hybrid heterostructures made of materials with an intrinsic large lattice mismatch.

  17. Band gap characterization of ternary BBi1−xNx (0≤x≤1) alloys using modified Becke–Johnson (mBJ) potential

    International Nuclear Information System (INIS)

    Yalcin, Battal G.

    2015-01-01

    The semi-local Becke–Johnson (BJ) exchange-correlation potential and its modified form proposed by Tran and Blaha have attracted a lot of interest recently because of the surprisingly accurate band gaps they can deliver for many semiconductors and insulators (e.g., sp semiconductors, noble-gas solids, and transition-metal oxides). The structural and electronic properties of ternary alloys BBi 1−x N x (0≤x≤1) in zinc-blende phase have been reported in this study. The results of the studied binary compounds (BN and BBi) and ternary alloys BBi 1−x N x structures are presented by means of density functional theory. The exchange and correlation effects are taken into account by using the generalized gradient approximation (GGA) functional of Wu and Cohen (WC) which is an improved form of the most popular Perdew–Burke–Ernzerhof (PBE). For electronic properties the modified Becke–Johnson (mBJ) potential, which is more accurate than standard semi-local LDA and PBE calculations, has been chosen. Geometric optimization has been implemented before the volume optimization calculations for all the studied alloys structure. The obtained equilibrium lattice constants of the studied binary compounds are in coincidence with experimental works. And, the variation of the lattice parameter of ternary alloys BBi 1−x N x almost perfectly matches with Vegard's law. The spin–orbit interaction (SOI) has been also considered for structural and electronic calculations and the results are compared to those of non-SOI calculations

  18. Principle, function, experiences, hybrid chilled ceilings; Prinzip, Funktion, Erfahrungen. Hybrid-Kuehldecken

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, Uwe W. [Hochschule Luzern (Switzerland). Technik und Architektur

    2010-12-15

    Hybrid chilled ceilings combine a radiation chilled ceiling with thermal activations of a concrete ceiling. The activation permits the utilization of alternative and/or small cold generators for the efficient night cooling. The traditional chilled ceiling grants a speedy reaction to load variations as well as a reduction of the reverberation periods. In addition, the combination supplies a draught-free insertion of air. Beside established solutions, MWH Barcol-Air (Staefa, Switzerland) also offers project-specific hybrid chilled ceilings.

  19. 28 CFR 0.28 - General functions.

    Science.gov (United States)

    2010-07-01

    ... Affairs § 0.28 General functions. The Office of Public Affairs is headed by a Director of Public Affairs who shall: (a) Handle matters pertaining to relations with the public generally. (b) Disseminate... 28 Judicial Administration 1 2010-07-01 2010-07-01 false General functions. 0.28 Section 0.28...

  20. The resilient hybrid fiber sensor network with self-healing function

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shibo, E-mail: Shibo-Xu@tju.edu.cn; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia [College of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China); Key Laboratory of Opto-electronics Information Technology (Tianjin University), Ministry of Education, Tianjin 300072 (China)

    2015-03-15

    This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.

  1. The resilient hybrid fiber sensor network with self-healing function

    Science.gov (United States)

    Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia

    2015-03-01

    This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands.

  2. The resilient hybrid fiber sensor network with self-healing function

    International Nuclear Information System (INIS)

    Xu, Shibo; Liu, Tiegen; Ge, Chunfeng; Chen, Qinnan; Zhang, Hongxia

    2015-01-01

    This paper presents a novel resilient fiber sensor network (FSN) with multi-ring architecture, which could interconnect various kinds of fiber sensors responsible for more than one measurands. We explain how the intelligent control system provides sensors with self-healing function meanwhile sensors are working properly, besides each fiber in FSN is under real-time monitoring. We explain the software process and emergency mechanism to respond failures or other circumstances. To improve the efficiency in the use of limited spectrum resources in some situations, we have two different structures to distribute the light sources rationally. Then, we propose a hybrid sensor working in FSN which is a combination of a distributed sensor and a FBG (Fiber Bragg Grating) array fused in a common fiber sensing temperature and vibrations simultaneously with neglectable crosstalk to each other. By making a failure to a working fiber in experiment, the feasibility and effectiveness of the network with a hybrid sensor has been demonstrated, hybrid sensors could not only work as designed but also survive from destructive failures with the help of resilient network and smart and quick self-healing actions. The network has improved the viability of the fiber sensors and diversity of measurands

  3. Hybrid functional band gap calculation of SnO{sub 6} containing perovskites and their derived structures

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyewon [Department of Physics, Pusan National University, Pusan 609-735, Republic of South Korea (Korea, Republic of); Cheong, S.W. [Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854 (United States); Kim, Bog G., E-mail: boggikim@pusan.ac.kr [Department of Physics, Pusan National University, Pusan 609-735, Republic of South Korea (Korea, Republic of)

    2015-08-15

    We have studied the properties of SnO{sub 6} octahedra-containing perovskites and their derived structures using ab initio calculations with different density functionals. In order to predict the correct band gap of the materials, we have used B3LYP hybrid density functional, and the results of B3LYP were compared with those obtained using the local density approximation and generalized gradient approximation data. The calculations have been conducted for the orthorhombic ground state of the SnO{sub 6} containing perovskites. We also have expended the hybrid density functional calculation to the ASnO{sub 3}/A'SnO{sub 3} system with different cation orderings. We propose an empirical relationship between the tolerance factor and the band gap of SnO{sub 6} containing oxide materials based on first principles calculation. - Graphical abstract: (a) Structure of ASnO{sub 3} for orthorhombic ground state. The green ball is A (Ba, Sr, Ca) cation and the small (red) ball on edge is oxygen. SnO{sub 6} octahedrons are plotted as polyhedron. (b) Band gap of ASnO{sub 3} as a function of the tolerance factor for different density functionals. The experimental values of the band gap are marked as green pentagons. (c) ASnO{sub 3}/A'SnO{sub 3} superlattices with two types cation arrangement: [001] layered structure and [111] rocksalt structure, respectively. (d) B3LYP hybrid functional band gaps of ASnO{sub 3}, [001] ordered superlattices, and [111] ordered superlattices of ASnO{sub 3}/A'SnO{sub 3} as a function of the effective tolerance factor. Note the empirical linear relationship between the band gap and effective tolerance factor. - Highlights: • We report the hybrid functional band gap calculation of ASnO{sub 3} and ASnO{sub 3}/A'SnO{sub 3}. • The band gap of ASnO{sub 3} using B3LYP functional reproduces the experimental value. • We propose the linear relationship between the tolerance factor and the band gap.

  4. Benchmarking Density Functional Theory Based Methods To Model NiOOH Material Properties: Hubbard and van der Waals Corrections vs Hybrid Functionals.

    Science.gov (United States)

    Zaffran, Jeremie; Caspary Toroker, Maytal

    2016-08-09

    NiOOH has recently been used to catalyze water oxidation by way of electrochemical water splitting. Few experimental data are available to rationalize the successful catalytic capability of NiOOH. Thus, theory has a distinctive role for studying its properties. However, the unique layered structure of NiOOH is associated with the presence of essential dispersion forces within the lattice. Hence, the choice of an appropriate exchange-correlation functional within Density Functional Theory (DFT) is not straightforward. In this work, we will show that standard DFT is sufficient to evaluate the geometry, but DFT+U and hybrid functionals are required to calculate the oxidation states. Notably, the benefit of DFT with van der Waals correction is marginal. Furthermore, only hybrid functionals succeed in opening a bandgap, and such methods are necessary to study NiOOH electronic structure. In this work, we expect to give guidelines to theoreticians dealing with this material and to present a rational approach in the choice of the DFT method of calculation.

  5. Ternary semiconductors NiZrSn and CoZrBi with half-Heusler structure: A first-principles study

    Science.gov (United States)

    Fiedler, Gregor; Kratzer, Peter

    2016-08-01

    The ternary semiconductors NiZrSn and CoZrBi with C 1b crystal structure are introduced by calculating their basic structural, electronic, and phononic properties using density functional theory. Both the gradient-corrected PBE functional and the hybrid functional HSE06 are employed. While NiZrSn is found to be a small-band-gap semiconductor (Eg=0.46 eV in PBE and 0.60 eV in HSE06), CoZrBi has a band gap of 1.01 eV in PBE (1.34 eV in HSE06). Moreover, effective masses and deformation potentials are reported. In both materials A B C , the intrinsic point defects introduced by species A (Ni or Co) are calculated. The Co-induced defects in CoZrBi are found to have a higher formation energy compared to Ni-induced defects in NiZrSn. The interstitial Ni atom (Nii) as well as the VNiNii complex introduce defect states in the band gap, whereas the Ni vacancy (VNi) only reduces the size of the band gap. While Nii is electrically active and may act as a donor, the other two types of defects may compensate extrinsic doping. In CoZrBi, only the VCoCoi complex introduces a defect state in the band gap. Motivated by the reported use of NiZrSn for thermoelectric applications, the Seebeck coefficient of both materials, both in the p -type and the n -type regimes, is calculated. We find that CoZrBi displays a rather large thermopower of up to 500 μ V /K when p doped, whereas NiZrSn possesses its maximum thermopower in the n -type regime. The reported difficulties in achieving p -type doping in NiZrSn could be rationalized by the unintended formation of Nii2 + in conjunction with extrinsic acceptors, resulting in their compensation. Moreover, it is found that all types of defects considered, when present in concentrations as large as 3%, tend to reduce the thermopower compared to ideal bulk crystals at T =600 K. For NiZrSn, the calculated thermodynamic data suggest that additional Ni impurities could be removed by annealing, leading to precipitation of a metallic Ni2ZrSn phase.

  6. Screened exchange hybrid density functional for accurate and efficient structures and interaction energies.

    Science.gov (United States)

    Brandenburg, Jan Gerit; Caldeweyher, Eike; Grimme, Stefan

    2016-06-21

    We extend the recently introduced PBEh-3c global hybrid density functional [S. Grimme et al., J. Chem. Phys., 2015, 143, 054107] by a screened Fock exchange variant based on the Henderson-Janesko-Scuseria exchange hole model. While the excellent performance of the global hybrid is maintained for small covalently bound molecules, its performance for computed condensed phase mass densities is further improved. Most importantly, a speed up of 30 to 50% can be achieved and especially for small orbital energy gap cases, the method is numerically much more robust. The latter point is important for many applications, e.g., for metal-organic frameworks, organic semiconductors, or protein structures. This enables an accurate density functional based electronic structure calculation of a full DNA helix structure on a single core desktop computer which is presented as an example in addition to comprehensive benchmark results.

  7. Mechanical characterization of hybrid and functionally-graded aluminum open-cell foams with nanocrystalline-copper coatings

    Science.gov (United States)

    Sun, Yi

    Cellular/foam materials found in nature such as bone, wood, and bamboo are usually functionally graded by having a non-uniform density distribution and inhomogenous composition that optimizes their global mechanical performance. Inspired by such naturally engineered products, the current study was conducted towards the development of functionally graded hybrid metal foams (FGHMF) with electrodeposited (ED) nanocrystalline coatings. First, the deformation and failure mechanisms of aluminum/copper (Al/Cu) hybrid foams were investigated using finite element analyses at different scales. The micro-scale behavior was studied based on single ligament models discretized using continuum elements and the macro-scale behavior was investigated using beam-element based finite element models of representative unit volumes consisting of multiple foam cells. With a detailed constitutive material behavior and material failure considered for both the aluminum ligament and the nano-copper coating, the numerical models were able to capture the unique behavior of Al/Cu hybrid foams, such as the typically observed sudden load drop after yielding. The numerical models indicate that such load drop is caused by the fracture of foam ligaments initiated from the rupture of the ED nano-copper coating due to its low ductility. This failure mode jeopardizes the global energy absorption capacity of hybrid foams, especially when a thick coating is applied. With the purpose of enhancing the performance of Al/Cu hybrid foams, an annealing process, which increased the ductility of the nanocrystalline copper coating by causing recovery, recrystallination and grain growth, was introduced in the manufacturing of Al/Cu hybrid foams. Quasi-static experimental results indicate that when a proper amount of annealing is applied, the ductility of the ED copper can be effectively improved and the compressive and tensile behavior of Al/Cu hybrid foams can be significantly enhanced, including better energy

  8. Ethanolic extract of Piper betle Linn. leaves reduces nociception via modulation of arachidonic acid pathway.

    Science.gov (United States)

    De, Soumita; Maroo, Niteeka; Saha, Piu; Hazra, Samik; Chatterjee, Mitali

    2013-01-01

    The objective of this study was to evaluate the peripheral analgesic effect of Piper betle leaf extract (PBE) along with establishing its putative mechanism of action. Male Swiss albino mice after pre-treatment (1 h) with different doses of PBE were injected 0.8% (v/v) acetic acid i.p.; the onset and number of writhes were noted up to 15 min. To evaluate the mechanism of action, the murine peritoneal exudate was incubated with PBE for 1 h, followed by exposure to arachidonic acid (AA) and generation of reactive oxygen species (ROS) was measured by flow cytometry using 2',7'-dichlorodihydrofluorescein diacetate. PBE in a dose dependent manner significantly reduced acetic acid induced writhing response in mice (P < 0.001). In peritoneal exudates, PBE significantly inhibited AA induced generation of ROS, P < 0.01. The present study indicates that PBE has promising analgesic activity, worthy of future pharmacological consideration.

  9. Allelic asymmetry of the Lethal hybrid rescue (Lhr) gene expression in the hybrid between Drosophila melanogaster and D. simulans: confirmation by using genetic variations of D. melanogaster.

    Science.gov (United States)

    Shirata, Mika; Araye, Quenta; Maehara, Kazunori; Enya, Sora; Takano-Shimizu, Toshiyuki; Sawamura, Kyoichi

    2014-02-01

    In the cross between Drosophila melanogaster females and D. simulans males, hybrid males die at the late larval stage, and the sibling females also die at later stages at high temperatures. Removing the D. simulans allele of the Lethal hybrid rescue gene (Lhr (sim) ) improves the hybrid incompatibility phenotypes. However, the loss-of-function mutation of Lhr (sim) (Lhr (sim0) ) does not rescue the hybrid males in crosses with several D. melanogaster strains. We first describe the genetic factor possessed by the D. melanogaster strains. It has been suggested that removing the D. melanogaster allele of Lhr (Lhr (mel) ), that is Lhr (mel0) , does not have the hybrid male rescue effect, contrasting to Lhr (sim0) . Because the expression level of the Lhr gene is known to be Lhr (sim) > Lhr (mel) in the hybrid, Lhr (mel0) may not lead to enough of a reduction in total Lhr expression. Then, there is a possibility that the D. melanogaster factor changes the expression level to Lhr (sim) Lhr (mel) in the hybrid irrespectively of the presence of the factor. At last, we showed that Lhr (mel0) slightly improves the viability of hybrid females, which was not realized previously. All of the present results are consistent with the allelic asymmetry model of the Lhr gene expression in the hybrid.

  10. Hybrid bulk heterojunction solar cells based on poly(3-hexylthiophene) and ZnO nanoparticles modified by side-chain functional polythiophenes

    International Nuclear Information System (INIS)

    Li, Fan; Du, Yanhui; Chen, Yiwang

    2012-01-01

    We report the investigation of the hybrid bulk heterojunction solar cells based on the blend of poly(3-hexylthiophene) (P3HT) and ZnO nanoparticles modified by side-chain thiol functional poly(3-thiophenehexanethiol) (P3HT-SH). Grafting of P3HT-SH onto ZnO nanoparticles can promote the dispersion of ZnO nanoparticles within P3HT matrix and facilitate electron injection process into ZnO nanoparticles, resulting in a more efficient photoinduced charge transfer than that in simple physical mixture of P3HT and non-modified ZnO nanoparticles (P3HT/ZnO). Furthermore, the performance of hybrid photovoltaic device based on P3HT/P3HT-SH-modified ZnO blend exhibits an improved device efficiency compared with P3HT/ZnO even before thermal treatment. After being annealed at 80 °C, the P3HT/P3HT-SH-modified ZnO device shows the power conversion efficiency as high as 0.68%, with the short-circuit current density of 1.89 mA/cm 2 , the open-circuit voltage of 0.599 V and a fill factor of 60.5% under AM 1.5 G illumination with 100 mW/cm 2 light intensity. - Highlights: ► Hybrid solar cells based on poly(3-hexylthiophene) and modified ZnO nanoparticles ► ZnO nanoparticles modified by side-chain functional polythiophenes ► Uniform dispersion and intimate contact between polymers and nanoparticles ► Efficient charge transfer leading to the improvement of device efficiency

  11. Comparison of some dispersion-corrected and traditional functionals as applied to peptides and conformations of cyclohexane derivatives

    Science.gov (United States)

    Marianski, Mateusz; Asensio, Amparo; Dannenberg, J. J.

    2012-07-01

    We compare the energetic and structural properties of fully optimized α-helical and antiparallel β-sheet polyalanines and the energetic differences between axial and equatorial conformations of three cyclohexane derivatives (methyl, fluoro, and chloro) as calculated using several functionals designed to treat dispersion (B97-D, ωB97x-D, M06, M06L, and M06-2X) with other traditional functionals not specifically parametrized to treat dispersion (B3LYP, X3LYP, and PBE1PBE) and with experimental results. Those functionals developed to treat dispersion significantly overestimate interaction enthalpies of folding for the α-helix and predict unreasonable structures that contain Ramachandran ϕ and ψ and C = O…N H-bonding angles that are out of the bounds of databases compiled the β-sheets. These structures are consistent with overestimation of the interaction energies. For the cyclohexanes, these functionals overestimate the stabilities of the axial conformation, especially when used with smaller basis sets. Their performance improves when the basis set is improved from D95** to aug-cc-pVTZ (which would not be possible with systems as large as the peptides).

  12. Binary Channel SAW Mustard Gas Sensor Based on PdPc0.3PANI0.7 hybrid Sensitive Film

    International Nuclear Information System (INIS)

    Shi, Y B; Xiang, J J; Feng, Q H; Hu, Z P; Zhang, H Q; Guo, J Y

    2006-01-01

    This paper discussed the working principle of binary channel surface acoustic wave (SAW) lithium niobate piezoelectric chip detecting mustard, established the mathematic model of beat frequency output Δf and the mustard gas density δ. The MEMS craft solved the parameters of the binary channel SAW chip such as its interdigital electrode number was 15∼25 couple, width and spacing were both 25μm, degree of overlapping was 2mm, fundamental frequency was 10∼35MHz, frequency-domain width was 5∼20Hz, and its back pt hot film's. According to TG-DSC thermal analysis, vacuum coating craft was adopted to solve the hybrid sensitive film forming craft parameter of PdPc 0.3 PANI 0.7 (phthalocyanine palladium 0.3 Poiyaniline 0.7 ). The micro-appearance of sensitive film was analyzed through SEM. The sensor's sensitivity and response characteristic were tested and analyzed: appear linear change, its response time is less than 5min while its recovery time is less than 8min

  13. Long-Range Corrected Hybrid Density Functionals with Damped Atom-Atom Dispersion Corrections

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Jeng-Da; Head-Gordon, Martin

    2008-06-14

    We report re-optimization of a recently proposed long-range corrected (LC) hybrid density functionals [J.-D. Chai and M. Head-Gordon, J. Chem. Phys. 128, 084106 (2008)] to include empirical atom-atom dispersion corrections. The resulting functional, {omega}B97X-D yields satisfactory accuracy for thermochemistry, kinetics, and non-covalent interactions. Tests show that for non-covalent systems, {omega}B97X-D shows slight improvement over other empirical dispersion-corrected density functionals, while for covalent systems and kinetics, it performs noticeably better. Relative to our previous functionals, such as {omega}B97X, the new functional is significantly superior for non-bonded interactions, and very similar in performance for bonded interactions.

  14. Cardiac hybrid imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gaemperli, Oliver [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland)

    2014-05-15

    Hybrid cardiac single photon emission computed tomography (SPECT)/CT imaging allows combined assessment of anatomical and functional aspects of cardiac disease. In coronary artery disease (CAD), hybrid SPECT/CT imaging allows detection of coronary artery stenosis and myocardial perfusion abnormalities. The clinical value of hybrid imaging has been documented in several subsets of patients. In selected groups of patients, hybrid imaging improves the diagnostic accuracy to detect CAD compared to the single imaging techniques. Additionally, this approach facilitates functional interrogation of coronary stenoses and guidance with regard to revascularization procedures. Moreover, the anatomical information obtained from CT coronary angiography or coronary artery calcium scores (CACS) adds prognostic information over perfusion data from SPECT. The use of cardiac hybrid imaging has been favoured by the dissemination of dedicated hybrid systems and the release of dedicated image fusion software, which allow simple patient throughput for hybrid SPECT/CT studies. Further technological improvements such as more efficient detector technology to allow for low-radiation protocols, ultra-fast image acquisition and improved low-noise image reconstruction algorithms will be instrumental to further promote hybrid SPECT/CT in research and clinical practice. (orig.)

  15. Using non-empirically tuned range-separated functionals with simulated emission bands to model fluorescence lifetimes.

    Science.gov (United States)

    Wong, Z C; Fan, W Y; Chwee, T S; Sullivan, Michael B

    2017-08-09

    Fluorescence lifetimes were evaluated using TD-DFT under different approximations for the emitting molecule and various exchange-correlation functionals, such as B3LYP, BMK, CAM-B3LYP, LC-BLYP, M06, M06-2X, M11, PBE0, ωB97, ωB97X, LC-BLYP*, and ωB97X* where the range-separation parameters in the last two functionals were tuned in a non-empirical fashion. Changes in the optimised molecular geometries between the ground and electronically excited states were found to affect the quality of the calculated lifetimes significantly, while the inclusion of vibronic features led to further improvements over the assumption of a vertical electronic transition. The LC-BLYP* functional was found to return the most accurate fluorescence lifetimes with unsigned errors that are mostly within 1.5 ns of experimental values.

  16. Organic-inorganic hybrid foams with diatomite addition: Effect on functional properties

    Science.gov (United States)

    Verdolotti, L.; D'Auria, M.; Lavorgna, M.; Vollaro, P.; Iannace, S.; Capasso, I.; Galzerano, B.; Caputo, D.; Liguori, B.

    2016-05-01

    Organic-inorganic hybrid foams were prepared by using metakaolin, diatomite as a partial (or total) replacement of metakaolin, as matrix, silicon and whipped protein as pore forming. The foamed systems were hardened at defined temperature and time and then characterized by mechanical point of view through compression tests and by functional point of view through fire reaction and acoustic tests. The experimental findings highlighted that the replacement of diatomite in the formulation affected the morphological structure of the foams and consequently their mechanical properties. In particular, the consolidation mechanism in the diatomite based-hybrid foams changed from geopolymerization to a silicate polycondensation mechanism. Therefore, mechanical performances enhanced with increasing of the diatomite content. Fire reaction tests, such as non-combustibility and cone calorimeter tests, showed positive thermal inertia of samples regardless of the content of diatomite.

  17. Study of the modes of adsorption and electronic structure of hydrogen peroxide and ethanol over TiO2 rutile (110) surface within the context of water splitting

    Science.gov (United States)

    Alghamdi, H.; Idriss, H.

    2018-03-01

    While photocatalytic water splitting over many materials is favourable thermodynamically the kinetic of the reaction is very slow. One of the proposed reasons linked to the slow oxidation reaction rate is H2O2 formation as a reaction intermediate. Using Density Functional Theory (DFT) H2O2 is investigated on TiO2 rutile (110) surface to determine its most stable adsorption modes: molecular, (H)O(H)O - (a), partially dissociated, (H)OO - (a), and fully dissociated (a) - OO - (a). We then compare H2O2 interaction to that of a fast hole scavenger molecule, ethanol. Geometry, electronic structure, charge density difference and work function determination of both adsorbates are presented and compared using DFT with different functionals (PBE, PBE-D, PBE-U, and HSE + D). H2O2 is found to be strongly adsorbed on TiO2 rutile (110) surface with adsorption energies reaching 0.95 eV, comparable to that of ethanol (0.89 eV); using GGA PBE. The negative changes in the work function upon adsorption were found to be highest for molecular adsorption ( - 1.23 eV) and lowest for the fully dissociated mode ( - 0.54 eV) of H2O2. This may indicate that electrons flow from the surface to the adsorbate in order to make O(s)-H partially offset the overall magnitude of the oxygen lone pair interaction (of H2O2) with Ti4+ cations. Examination of the electronic structure through density of states (DOS) at the PBE level of computation, indicates that the H2O2 highest occupied molecular orbital (HOMO) level is not overlapping with oxygen atoms of TiO2 surface at any of its adsorption modes and at any of the computation methods. Some overlap is seen using the HSE + D computational method. On the other hand the dissociated mode of ethanol (ethoxides) does overlap with all computational methods used. The high adsorption energy and the absence of overlapping of the HOMO level of H2O2 with TiO2 rutile (110) surface may explain why water splitting is slow.

  18. Density Functional Theory Study of Competitive Reaction Pathways of Ti+ with Fluorinated Acetone in the Gas Phase

    International Nuclear Information System (INIS)

    Hong, Kiryong; Kim, Tae Kyu

    2012-01-01

    We investigate the doublet and quartet potential energy surfaces associated with the gas-phase reaction between Ti + and CF 3 COCH 3 for two plausible reaction pathways, TiF 2 + and TiO + formation pathways by using the density functional theory (DFT) method. The molecular structures of intermediates and transition states involved in these reaction pathways are optimized at the DFT level by using the PBE0 functional. All transition states are identified by using the intrinsic reaction coordinate (IRC) method, and the resulting reaction coordinates describe how Ti + activates CF 3 COCH 3 and produces TiF 2 + and TiO + as products. On the basis of presented results, we propose the most favorable reaction pathway in the reaction between Ti + and CF 3 COCH 3

  19. Functionally graded scaffolds for the engineering of interface tissues using hybrid twin screw extrusion/electrospinning technology

    Science.gov (United States)

    Erisken, Cevat

    Tissue engineering is the application of the principles of engineering and life sciences for the development of biological alternatives for improvement or regeneration of native tissues. Native tissues are complex structures with functions and properties changing spatially and temporally, and engineering of such structures requires functionally graded scaffolds with composition and properties changing systematically along various directions. Utilization of a new hybrid technology integrating the controlled feeding, compounding, dispersion, deaeration, and pressurization capabilities of extrusion process with electrospinning allows incorporation of liquids and solid particles/nanoparticles into polymeric fibers/nanofibers for fabrication of functionally graded non-woven meshes to be used as scaffolds in engineering of tissues. The capabilities of the hybrid technology were demonstrated with a series of scaffold fabrication and cell culturing studies along with characterization of biomechanical properties. In the first study, the hybrid technology was employed to generate concentration gradations of beta-tricalcium phosphate (beta-TCP) nanoparticles in a polycaprolactone (PCL) binder, between two surfaces of nanofibrous scaffolds. These scaffolds were seeded with pre-osteoblastic cell line (MC3T3-E1) to attempt to engineer cartilage-bone interface, and after four weeks, the tissue constructs revealed formation of continuous gradations in extracellular matrix akin to cartilage-bone interface in terms of distributions of mineral concentrations and biomechanical properties. In a second demonstration of the hybrid technology, graded differentiation of stem cells was attempted by using insulin, a known stimulator of chondrogenic differentiation, and beta-glycerol phosphate (beta-GP), for mineralization. Concentrations of insulin and beta-GP in PCL were controlled to monotonically increase and decrease, respectively, along the length of scaffolds, which were then seeded

  20. First-principles calculations on double-walled inorganic nanotubes with hexagonal chiralities

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, Yuri F [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063, Riga (Latvia); Evarestov, Robert A; Bandura, Andrei V; Losev, Maxim V, E-mail: quantzh@latnet.lv [Department of Quantum Chemistry, St. Petersburg State University, 26 Universitetsky Ave., 198504, Petrodvorets (Russian Federation)

    2011-06-23

    The two sets of commensurate double-walled boron nitride and titania hexagonally-structured nanotubes (DW BN and TiO{sub 2} NTs) possessing either armchair- or zigzag-type chiralities have been considered, i.e., (n{sub 1},n{sub 1})-(n{sub 2},n{sub 2}) or (n{sub 1},0)-(n{sub 2},0), respectively. For symmetry analysis of these nanotubes, the line symmetry groups for one-periodic (1D) nanostructures with rotohelical symmetry have been applied. To analyze the structural and electronic properties of hexagonal DW NTs, a series of large-scale ab initio DFT-LCAO calculations have been performed using the hybrid Hartree-Fock/Kohn-Sham exchange-correlation functional PBE0 (as implemented in CRYSTAL-09 code). To establish the optimal inter-shell distances within DW NTs corresponding to the minima of calculated total energy, the chiral indices n{sub 1} and n{sub 2} of the constituent single-walled (SW) nanotubes have been successively varied.

  1. A chromophoric study of 2-ethylhexyl p-methoxycinnamate

    Science.gov (United States)

    Alves, Leonardo F.; Gargano, Ricardo; Alcanfor, Silvia K. B.; Romeiro, Luiz A. S.; Martins, João B. L.

    2011-11-01

    Ultraviolet absorption spectra of 2-ethylhexyl p-methoxycinnamate have been recorded in different solvents and calculated using the time dependent density functional theory. The calculations were performed with the aid of B3LYP, PBE1PBE, M06, and PBEPBE functionals and 6-31+G(2d) basis set. The geometries were initially optimized using PM5 semiempirical method for the conformational search. The calculations of excited states were carried out using the time dependent with IEF-PCM solvent reaction field method. The experimental data were obtained in the wavelength range from 200 to 400 nm using 10 different solvents. The TD-PBE1PBE method shows the best agreement to the experimental results.

  2. On the performance of quantum chemical methods to predict solvatochromic effects. The case of acrolein in aqueous solution

    DEFF Research Database (Denmark)

    Aidas, Kestutis; Møgelhøj, Andreas; Nilsson, Elna Johanna Kristina

    2008-01-01

    The performance of the Hartree–Fock method and the three density functionals B3LYP, PBE0, and CAM-B3LYP is compared to results based on the coupled cluster singles and doubles model in predictions of the solvatochromic effects on the vertical n¿* and ¿* electronic excitation energies of acrolein...... of acrolein in vapor phase and aqueous solution. The gas-to-aqueous solution shift of the n¿* excitation energy is well reproduced by using all density functional methods considered. However, the B3LYP and PBE0 functionals completely fail to describe the ¿* electronic transition in solution, whereas...... the recent CAM-B3LYP functional performs well also in this case. The ¿* excitation energy of acrolein in water solution is found to be very dependent on intermolecular induction and nonelectrostatic interactions. The computed excitation energies of acrolein in vacuum and solution compare well to experimental...

  3. Magnetic Exchange Couplings from Semilocal Functionals Evaluated Nonself-Consistently on Hybrid Densities: Insights on Relative Importance of Exchange, Correlation, and Delocalization.

    Science.gov (United States)

    Phillips, Jordan J; Peralta, Juan E

    2012-09-11

    Semilocal functionals generally yield poor magnetic exchange couplings for transition-metal complexes, typically overpredicting in magnitude the experimental values. Here we show that semilocal functionals evaluated nonself-consistently on densities from hybrid functionals can yield magnetic exchange couplings that are greatly improved with respect to their self-consistent semilocal values. Furthermore, when semilocal functionals are evaluated nonself-consistently on densities from a "half-and-half" hybrid, their errors with respect to experimental values can actually be lower than those from self-consistent calculations with standard hybrid functionals such as PBEh or TPSSh. This illustrates that despite their notoriously poor performance for exchange couplings, for many systems semilocal functionals are capable of delivering accurate relative energies for magnetic states provided that their electron delocalization error is corrected. However, while self-consistent calculations with hybrids uniformly improve results for all complexes, evaluating nonself-consistently with semilocal functionals does not give a balanced improvement for both ferro- and antiferromagnetically coupled complexes, indicating that there is more at play with the overestimation problem than simply the delocalization error. Additionally, we show that for some systems the conventional wisdom of choice of exchange functional mattering more than correlation does not hold. This combined with results from the nonself-consistent calculations provide insight on clarifying the relative roles of exchange, correlation, and delocalization in calculating magnetic exchange coupling parameters in Kohn-Sham Density Functional Theory.

  4. Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory

    DEFF Research Database (Denmark)

    Hempler, Daniela; Schmidt, Martin U.; Van De Streek, Jacco

    2017-01-01

    More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic...... with missed symmetry were investigated by dispersion-corrected density functional theory. In 98.5% of the cases the correct space group is found....

  5. Hybrid phase-locked loop with fast locking time and low spur in a 0.18-μm CMOS process

    Science.gov (United States)

    Zhu, Si-Heng; Si, Li-Ming; Guo, Chao; Shi, Jun-Yu; Zhu, Wei-Ren

    2014-07-01

    We propose a novel hybrid phase-locked loop (PLL) architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator (VCO) and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor (CMOS) process with a total die area of 1.4×0.46 mm2. The measured results exhibit a reference spur level of lower than -73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V.

  6. 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.

  7. Investigating actinide compounds within a hybrid MCSCF-DFT model

    International Nuclear Information System (INIS)

    Fromager, E.; Jensen, H.J.A.; Wahlin, P.; Real, F.; Wahlgren, U.

    2007-01-01

    definition of an optimal μ opt parameter [3], independent of the approximate short-range functional and the approximate (MCSCF) wave function, is applied in this work. Recently reviewed calculations on light elements yielded μ opt ∼ 0.4 a.u [3], which is in agreement with previous calibration studies. A new numerical investigation of μ opt is now presented for actinides. A test set consisting of ThO 2 , PaO 2 + , UO 2 2+ , UCO and UN 2 (representing cases without significant static correlation) as well as NpO 2 3+ and PuO 2 4+ (representing cases with significant static correlation) has been considered. The bending problem of NpO 2 3+ and PuO 2 4+ observed in KS-DFT(B3LYP) is then addressed within the hybrid MCSCF-DFT approach. Calculations have been performed at the scalar relativistic level with the MCSCF-DFT code [4] implemented in a development version of the DALTON program package [5], using short-range LDA and PBE-type functionals [3. References [1] M. Straka, K.G. Dyall, and P. Pyykko, Theor. Chem. Acc., 106, 393 (2001); [2] A. Savin, in Recent Developments and Applications of Modern Density Functional Theory, edited by J.M. Seminario (Elsevier, Amsterdam, 1996), p. 327; [3] E. Fromager, J. Toulouse, and H. J. Aa. Jensen, J. Chem. Phys., in press; [4] J.K. Pedersen and H.J.A. Jensen, J. Chem. Phys., submitted; [5] T. Helgaker, H.J. Aa. Jensen, P. Jorgensen, J. Oelsen, K. Ruud, H. Agren, K.L. Bak, V. Bakken, O. Christiansen, S. Coriani, et al., Dalton release 2.0 (2005), an electronic structure program, www.kjemi.uio.no/software/dalton/dalton.html

  8. VV and VO2 defects in silicon studied with hybrid density functional theory

    KAUST Repository

    Christopoulos, Stavros Richard G

    2014-12-07

    The formation of VO (A-center), VV and VO2 defects in irradiated Czochralski-grown silicon (Si) is of technological importance. Recent theoretical studies have examined the formation and charge states of the A-center in detail. Here we use density functional theory employing hybrid functionals to analyze the formation of VV and VO2 defects. The formation energy as a function of the Fermi energy is calculated for all possible charge states. For the VV and VO2 defects double negatively charged and neutral states dominate, respectively.

  9. A Novel Shape-Free Plane Quadratic Polygonal Hybrid Stress-Function Element

    Directory of Open Access Journals (Sweden)

    Pei-Lei Zhou

    2015-01-01

    Full Text Available A novel plane quadratic shape-free hybrid stress-function (HS-F polygonal element is developed by employing the principle of minimum complementary energy and the fundamental analytical solutions of the Airy stress function. Without construction of displacement interpolation function, the formulations of the new model are much simpler than those of the displacement-based polygonal elements and can be degenerated into triangular or quadrilateral elements directly. In particular, it is quite insensitive to various mesh distortions and even can keep precision when element shape is concave. Furthermore, the element does not show any spurious zero energy modes. Numerical examples show the excellent performance of the new element, denoted by HSF-AP-19β, in both displacement and stress solutions.

  10. Hybrid2 - The hybrid power system simulation model

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, E.I.; Green, H.J.; Dijk, V.A.P. van [National Renewable Energy Lab., Golden, CO (United States); Manwell, J.F. [Univ. of Massachusetts, Amherst, MA (United States)

    1996-12-31

    There is a large-scale need and desire for energy in remote communities, especially in the developing world; however the lack of a user friendly, flexible performance prediction model for hybrid power systems incorporating renewables hindered the analysis of hybrids as options to conventional solutions. A user friendly model was needed with the versatility to simulate the many system locations, widely varying hardware configurations, and differing control options for potential hybrid power systems. To meet these ends, researchers from the National Renewable Energy Laboratory (NREL) and the University of Massachusetts (UMass) developed the Hybrid2 software. This paper provides an overview of the capabilities, features, and functionality of the Hybrid2 code, discusses its validation and future plans. Model availability and technical support provided to Hybrid2 users are also discussed. 12 refs., 3 figs., 4 tabs.

  11. Controlling the Morphology and Efficiency of Hybrid ZnO : Polythiophene Solar Cells Via Side Chain Functionalization

    NARCIS (Netherlands)

    Oosterhout, Stefan D.; Koster, L. Jan Anton; van Bavel, Svetlana S.; Loos, Joachim; Stenzel, Ole; Thiedmann, Ralf; Schmidt, Volker; Campo, Bert; Cleij, Thomas J.; Lutzen, Laurence; Vanderzande, Dirk; Wienk, Martijn M.; Janssen, Rene A. J.

    2011-01-01

    The efficiency of polymer - metal oxide hybrid solar cells depends critically on the intimacy of mixing of the two semiconductors. The effect of side chain functionalization on the morphology and performance of conjugated polymer:ZnO solar cells is investigated. Using an ester-functionalized side

  12. Optimum Dispatch of Hybrid Solar Thermal (HSTP Electric Power Plant Using Non-Smooth Cost Function and Emission Function for IEEE-30 Bus System

    Directory of Open Access Journals (Sweden)

    Saroj Kumar Dash

    2016-07-01

    Full Text Available The basic objective of economic load dispatch (ELD is to optimize the total fuel cost of hybrid solar thermal electric power plant (HSTP. In ELD problems the cost function for each generator has been approximated by a single quadratic cost equation. As cost of coal increases, it becomes even more important have a good model for the production cost of each generator for the solar thermal hybrid system. A more accurate formulation is obtained for the ELD problem by expressing the generation cost function as a piece wise quadratic cost function. However, the solution methods for ELD problem with piece wise quadratic cost function requires much complicated algorithms such as the hierarchical structure approach along with evolutionary computations (ECs. A test system comprising of 10 units with 29 different fuel [7] cost equations is considered in this paper. The applied genetic algorithm method will provide optimal solution for the given load demand.

  13. Electrochemical and anticorrosion behaviors of hybrid functionalized graphite nano-platelets/tripolyphosphate in epoxy-coated carbon steel

    International Nuclear Information System (INIS)

    Mohammadi, Somayeh; Shariatpanahi, Homeira; Taromi, Faramarz Afshar; Neshati, Jaber

    2016-01-01

    Highlights: • FGNP was combined with TPP to obtain a hybrid nano-particle. • TEM image showed uniform distribution of the hybrid nanoparticles in epoxy coating. • FGNP is a substrate for linking of TPP anions by hydrogen bonding. • FGNP as an accelerator, provides rapid iron phosphate passive film formation. • The hybrid nano-particle can provide long-term corrosion protection. - Abstract: Functionalized graphite nano-platelets (FGNP) were combined with tripolyphosphate (TPP) to gain a hybrid nano-particle (FGNP-TPP) with homogenous dispersion in epoxy, resulting in an excellent anti-corrosion coating for carbon steel substrate. Characterization analyses of the hybrid nano-particle were performed by FT-IR, SEM, XRD and TEM. TPP was linked to FGNP nano-particles by hydrogen bondings. Different epoxy coatings formulated with 1 wt.% of FGNP, FGNP-TPP and TPP were evaluated. Electrochemical investigations, salt spray and pull-off tests showed that the hybrid nano-particle can provide long-term corrosion protection compared to FGNP and TPP due to synergistic effect between FGNP as an accelerator and TPP as a corrosion inhibitor to produce a uniform and stable iron-phosphate passive film with high surface coverage.

  14. Electrochemical and anticorrosion behaviors of hybrid functionalized graphite nano-platelets/tripolyphosphate in epoxy-coated carbon steel

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Somayeh, E-mail: somaye.mohammadi32@aut.ac.ir [Department of Chemistry, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Shariatpanahi, Homeira [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of); Taromi, Faramarz Afshar [Department of Polymer Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Neshati, Jaber [Corrosion Department, Research Institute of Petroleum Industry (RIPI), P.O. Box 18745-4163, Tehran (Iran, Islamic Republic of)

    2016-08-15

    Highlights: • FGNP was combined with TPP to obtain a hybrid nano-particle. • TEM image showed uniform distribution of the hybrid nanoparticles in epoxy coating. • FGNP is a substrate for linking of TPP anions by hydrogen bonding. • FGNP as an accelerator, provides rapid iron phosphate passive film formation. • The hybrid nano-particle can provide long-term corrosion protection. - Abstract: Functionalized graphite nano-platelets (FGNP) were combined with tripolyphosphate (TPP) to gain a hybrid nano-particle (FGNP-TPP) with homogenous dispersion in epoxy, resulting in an excellent anti-corrosion coating for carbon steel substrate. Characterization analyses of the hybrid nano-particle were performed by FT-IR, SEM, XRD and TEM. TPP was linked to FGNP nano-particles by hydrogen bondings. Different epoxy coatings formulated with 1 wt.% of FGNP, FGNP-TPP and TPP were evaluated. Electrochemical investigations, salt spray and pull-off tests showed that the hybrid nano-particle can provide long-term corrosion protection compared to FGNP and TPP due to synergistic effect between FGNP as an accelerator and TPP as a corrosion inhibitor to produce a uniform and stable iron-phosphate passive film with high surface coverage.

  15. Masses of open-flavour heavy-light hybrids from QCD sum-rules

    Energy Technology Data Exchange (ETDEWEB)

    Ho, J. [Department of Physics and Engineering Physics, University of Saskatchewan,Saskatoon, SK, S7N 5E2 (Canada); Harnett, D. [Department of Physics, University of the Fraser Valley,Abbotsford, BC, V2S 7M8 (Canada); Steele, T.G. [Department of Physics and Engineering Physics, University of Saskatchewan,Saskatoon, SK, S7N 5E2 (Canada)

    2017-05-29

    We use QCD Laplace sum-rules to predict masses of open-flavour heavy-light hybrids where one of the hybrid’s constituent quarks is a charm or bottom and the other is an up, down, or strange. We compute leading-order, diagonal correlation functions of several hybrid interpolating currents, taking into account QCD condensates up to dimension-six, and extract hybrid mass predictions for all J{sup P}∈{0"±, 1"±}, as well as explore possible mixing effects with conventional quark-antiquark mesons. Within theoretical uncertainties, our results are consistent with a degeneracy between the heavy-nonstrange and heavy-strange hybrids in all J{sup P} channels. We find a similar mass hierarchy of 1{sup +}, 1{sup −}, and 0{sup +} states (a 1{sup +} state lighter than essentially degenerate 1{sup −} and 0{sup +} states) in both the charm and bottom sectors, and discuss an interpretation for the 0{sup −} states. If conventional meson mixing is present the effect is an increase in the hybrid mass prediction, and we estimate an upper bound on this effect.

  16. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Sissay, Adonay [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Lopata, Kenneth, E-mail: klopata@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2016-09-07

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  17. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    International Nuclear Information System (INIS)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J.; Lopata, Kenneth

    2016-01-01

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  18. Troubles in the systematic prediction of transition metal thermochemistry with contemporary out-of-the-box methods

    KAUST Repository

    Minenkov, Yury

    2016-03-22

    The recently developed DLPNO-CCSD(T) method and 7 popular DFT functionals (B3LYP, M06, M06L, PBE, PBE0, TPSS and TPSSh) with and without an empirical dispersion term have been tested to reproduce 111 gas phase reaction enthalpies involving 11 different transition metals. Our calculations, corrected for both relativistic effects and basis set incompleteness, indicate that most of the methods applied with default settings perform with acceptable accuracy on average. Nevertheless, our calculations also evidenced unexpected and non systematic large deviations for specific cases. For group 12 metals (Zn, Cd, Hg) most of the methods provided mean unsigned errors (MUE) less than 5.0 kcal/mol, with DLPNO-CCSD(T) and PBE methods performing excellently (MUE lower 2.0 kcal/mol). Problems started with group 4 metals (Ti and Zr). Best performer for Zr complexes with a MUE of 1.8 kcal/mol, PBE0-D3, provides a MUE larger than 8 kcal/mol for Ti. DLPNO-CCSD(T) provides a reasonable MUE of 3.3 kcal/mol for Ti reactions, but gives MUE a larger than 14.4 kcal/mol for Zr complexes, with all the larger deviations for reactions involving ZrF4. Large and non-systematic errors have been obtained for group 6 metals (Mo and W), for 8 reactions containing Fe, Cu, Nb and Re complexes. Finally, for the whole set of 111 reactions, the DLPNO-CCSD(T), B3LYP-D3 and PBE0-D3 methods turned out to be the best performers, both providing MUE below 5.0 kcal/mol. Since DFT results cannot be systematically improved and large non-systematic deviations of 20-30 kcal/mol were obtained even for best performers, our results indicates that current DFT methods are still unable to provide robust predictions in transition metal thermochemistry, at least for the functionals explored in this work. The same conclusion holds for both DLPNO-CCSD(T) and canonical CCSD(T) methods when used entirely as out-of-the-box. However if careful investigation core correlation is performed, relativistic effects are properly included

  19. BEAN 2.0: an integrated web resource for the identification and functional analysis of type III secreted effectors.

    Science.gov (United States)

    Dong, Xiaobao; Lu, Xiaotian; Zhang, Ziding

    2015-01-01

    Gram-negative pathogenic bacteria inject type III secreted effectors (T3SEs) into host cells to sabotage their immune signaling networks. Because T3SEs constitute a meeting-point of pathogen virulence and host defense, they are of keen interest to host-pathogen interaction research community. To accelerate the identification and functional understanding of T3SEs, we present BEAN 2.0 as an integrated web resource to predict, analyse and store T3SEs. BEAN 2.0 includes three major components. First, it provides an accurate T3SE predictor based on a hybrid approach. Using independent testing data, we show that BEAN 2.0 achieves a sensitivity of 86.05% and a specificity of 100%. Second, it integrates a set of online sequence analysis tools. Users can further perform functional analysis of putative T3SEs in a seamless way, such as subcellular location prediction, functional domain scan and disorder region annotation. Third, it compiles a database covering 1215 experimentally verified T3SEs and constructs two T3SE-related networks that can be used to explore the relationships among T3SEs. Taken together, by presenting a one-stop T3SE bioinformatics resource, we hope BEAN 2.0 can promote comprehensive understanding of the function and evolution of T3SEs. © The Author(s) 2015. Published by Oxford University Press.

  20. Controlling the morphology and efficiency of hybrid ZnO: Polythiophene solar cells via side chain functionalization

    NARCIS (Netherlands)

    Oosterhout, S.D.; Koster, L.J.A.; Bavel, van S.S.; Loos, J.; Stenzel, O.; Thiedmann, R.; Schmidt, V.; Campo, B.J.; Cleij, T.J.; Lutzen, L.; Vanderzande, D.J.M.; Wienk, M.M.; Janssen, R.A.J.

    2011-01-01

    The efficiency of polymer – metal oxide hybrid solar cells depends critically on the intimacy of mixing of the two semiconductors. The effect of side chain functionalization on the morphology and performance of conjugated polymer:ZnO solar cells is investigated. Using an ester-functionalized side

  1. Effects of an electric field on interaction of aromatic systems.

    Science.gov (United States)

    Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S

    2016-04-30

    The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc.

  2. Hybrid brain-computer interfaces and hybrid neuroprostheses for restoration of upper limb functions in individuals with high-level spinal cord injury.

    Science.gov (United States)

    Rohm, Martin; Schneiders, Matthias; Müller, Constantin; Kreilinger, Alex; Kaiser, Vera; Müller-Putz, Gernot R; Rupp, Rüdiger

    2013-10-01

    The bilateral loss of the grasp function associated with a lesion of the cervical spinal cord severely limits the affected individuals' ability to live independently and return to gainful employment after sustaining a spinal cord injury (SCI). Any improvement in lost or limited grasp function is highly desirable. With current neuroprostheses, relevant improvements can be achieved in end users with preserved shoulder and elbow, but missing hand function. The aim of this single case study is to show that (1) with the support of hybrid neuroprostheses combining functional electrical stimulation (FES) with orthoses, restoration of hand, finger and elbow function is possible in users with high-level SCI and (2) shared control principles can be effectively used to allow for a brain-computer interface (BCI) control, even if only moderate BCI performance is achieved after extensive training. The individual in this study is a right-handed 41-year-old man who sustained a traumatic SCI in 2009 and has a complete motor and sensory lesion at the level of C4. He is unable to generate functionally relevant movements of the elbow, hand and fingers on either side. He underwent extensive FES training (30-45min, 2-3 times per week for 6 months) and motor imagery (MI) BCI training (415 runs in 43 sessions over 12 months). To meet individual needs, the system was designed in a modular fashion including an intelligent control approach encompassing two input modalities, namely an MI-BCI and shoulder movements. After one year of training, the end user's MI-BCI performance ranged from 50% to 93% (average: 70.5%). The performance of the hybrid system was evaluated with different functional assessments. The user was able to transfer objects of the grasp-and-release-test and he succeeded in eating a pretzel stick, signing a document and eating an ice cream cone, which he was unable to do without the system. This proof-of-concept study has demonstrated that with the support of hybrid FES

  3. THE WYOMING SURVEY FOR Hα. II. Hα LUMINOSITY FUNCTIONS AT z∼ 0.16, 0.24, 0.32, AND 0.40

    International Nuclear Information System (INIS)

    Dale, Daniel A.; Cook, David O.; Moore, Carolynn A.; Staudaher, Shawn M.; Barlow, Rebecca J.; Cohen, Seth A.; Johnson, L. Clifton; Kattner, ShiAnne M.; Schuster, Micah D.

    2010-01-01

    The Wyoming Survey for Hα, or WySH, is a large-area, ground-based imaging survey for Hα-emitting galaxies at redshifts of z ∼ 0.16, 0.24, 0.32, and 0.40. The survey spans up to 4 deg 2 in a set of fields of low Galactic cirrus emission, using twin narrowband filters at each epoch for improved stellar continuum subtraction. Hα luminosity functions are presented for each Δz ∼ 0.02 epoch based on a total of nearly 1200 galaxies. These data clearly show an evolution with look-back time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the incompleteness- and extinction-corrected Hα luminosity functions indicate star formation rates per comoving volume of 0.010, 0.013, 0.020, 0.022 h 70 M sun yr -1 Mpc -3 at z ∼ 0.16, 0.24, 0.32, and 0.40, respectively. Combined statistical and systematic measurement uncertainties are on the order of 25%, while the effects of cosmic variance are at the 20% level. The bulk of this evolution is driven by changes in the characteristic luminosity L * of the Hα luminosity functions, with L * for the earlier two epochs being a factor of 2 larger than L * at the latter two epochs; it is more difficult with this data set to decipher systematic evolutionary differences in the luminosity function amplitude and faint-end slope. Coupling these results with a comprehensive compilation of results from the literature on emission line surveys, the evolution in the cosmic star formation rate density over 0 ∼< z ∼< 1.5 is measured.

  4. Heavy metals adsorption by novel EDTA-modified chitosan-silica hybrid materials.

    Science.gov (United States)

    Repo, Eveliina; Warchoł, Jolanta K; Bhatnagar, Amit; Sillanpää, Mika

    2011-06-01

    Novel adsorbents were synthesized by functionalizing chitosan-silica hybrid materials with (ethylenediaminetetraacetic acid) EDTA ligands. The synthesized adsorbents were found to combine the advantages of both silica gel (high surface area, porosity, rigid structure) and chitosan (surface functionality). The Adsorption potential of hybrid materials was investigated using Co(II), Ni(II), Cd(II), and Pb(II) as target metals by varying experimental conditions such as pH, contact time, and initial metal concentration. The kinetic results revealed that the pore diffusion process played a key role in adsorption kinetics, which might be attributed to the porous structure of synthesized adsorbents. The obtained maximum adsorption capacities of the hybrid materials for the metal ions ranged from 0.25 to 0.63 mmol/g under the studied experimental conditions. The adsorbent with the highest chitosan content showed the best adsorption efficiency. Bi-Langmuir and Sips isotherm model fitting to experimental data suggested the surface heterogeneity of the prepared adsorbents. In multimetal solutions, the hybrid adsorbents showed the highest affinity toward Pb(II). Copyright © 2011 Elsevier Inc. All rights reserved.

  5. From hybrid swarms to swarms of hybrids

    Science.gov (United States)

    Stohlgren, Thomas J.; Szalanski, Allen L; Gaskin, John F.; Young, Nicholas E.; West, Amanda; Jarnevich, Catherine S.; Tripodi, Amber

    2014-01-01

    Science has shown that the introgression or hybridization of modern humans (Homo sapiens) with Neanderthals up to 40,000 YBP may have led to the swarm of modern humans on earth. However, there is little doubt that modern trade and transportation in support of the humans has continued to introduce additional species, genotypes, and hybrids to every country on the globe. We assessed the utility of species distributions modeling of genotypes to assess the risk of current and future invaders. We evaluated 93 locations of the genus Tamarix for which genetic data were available. Maxent models of habitat suitability showed that the hybrid, T. ramosissima x T. chinensis, was slightly greater than the parent taxa (AUCs > 0.83). General linear models of Africanized honey bees, a hybrid cross of Tanzanian Apis mellifera scutellata and a variety of European honey bee including A. m. ligustica, showed that the Africanized bees (AUC = 0.81) may be displacing European honey bees (AUC > 0.76) over large areas of the southwestern U.S. More important, Maxent modeling of sub-populations (A1 and A26 mitotypes based on mDNA) could be accurately modeled (AUC > 0.9), and they responded differently to environmental drivers. This suggests that rapid evolutionary change may be underway in the Africanized bees, allowing the bees to spread into new areas and extending their total range. Protecting native species and ecosystems may benefit from risk maps of harmful invasive species, hybrids, and genotypes.

  6. 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.

  7. Hybrid phase-locked loop with fast locking time and low spur in a 0.18-μm CMOS process

    International Nuclear Information System (INIS)

    Zhu Si-Heng; Si Li-Ming; Guo Chao; Shi Jun-Yu; Zhu Wei-Ren

    2014-01-01

    We propose a novel hybrid phase-locked loop (PLL) architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator (VCO) and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor (CMOS) process with a total die area of 1.4×0.46 mm 2 . The measured results exhibit a reference spur level of lower than −73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V. (interdisciplinary physics and related areas of science and technology)

  8. Mechanically-competent and cytocompatible polycaprolactone-borophosphosilicate hybrid biomaterials.

    Science.gov (United States)

    Mondal, Dibakar; Dixon, S Jeffrey; Mequanint, Kibret; Rizkalla, Amin S

    2017-11-01

    Organic-inorganic class II hybrid materials have domain sizes at the molecular level and chemical bonding between the organic and inorganic phases. We have previously reported the synthesis of class II hybrid biomaterials from alkoxysilane-functionalized polycaprolactone (PCL) and borophosphosilicate (B 2 O 3 -P 2 O 5 -SiO 2 ) glass (BPSG) through a non-aqueous sol-gel process. In the present study, the mechanical properties and degradability of these PCL/BPSG hybrid biomaterials were studied and compared to those of their conventional composite counterparts. The compressive strength, modulus and toughness of the hybrid biomaterials were significantly greater compared to the conventional composites, likely due to the covalent bonding between the organic and inorganic phases. A hybrid biomaterial (50wt% PCL and 50wt% BPSG) exhibited compressive strength, modulus and toughness values of 32.2 ± 3.5MPa, 573 ± 85MPa and 1.54 ± 0.03MPa, respectively; whereas the values for composite of similar composition were 18.8 ± 1.6MPa, 275 ± 28MPa and 0.76 ± 0.03MPa, respectively. Degradation in phosphate-buffered saline was slower for hybrid biomaterials compared to their composite counterparts. Thus, these hybrid materials possess superior mechanical properties and more controlled degradation characteristics compared to their corresponding conventional composites. To assess in vitro cytocompatibility, MC3T3-E1 pre-osteoblastic cells were seeded onto the surfaces of hybrid biomaterials and polycaprolactone (control). Compared to polycaprolactone, cells on the hybrid material displayed enhanced spreading, focal adhesion formation, and cell number, consistent with excellent cytocompatibility. Thus, based on their mechanical properties, degradability and cytocompatibility, these novel biomaterials have potential for use as scaffolds in bone tissue engineering and related applications. Copyright © 2017. Published by Elsevier Ltd.

  9. Effect of treating alfalfa silage with pistachio by-products extract on Saanen dairy goats performance and microbial nitrogen synthesis.

    Science.gov (United States)

    Mokhtarpour, A; Naserian, A A; Pourmollae, F; Ghaffari, M H

    2016-08-01

    A lactation experiment was conducted to determine the influence of addition of pistachio by-products extract (PBE) to alfalfa silage (AS) on performance, rumen fermentation, milk yield and composition, and microbial nitrogen synthesis. Eight multiparous dairy goats (1.8 ± 0.25 kg of milk yield) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments to compare two types of AS (supplemented with or without PBE) with two levels of dietary crude protein (14% vs. 16% CP). Dietary treatments were (i) AS with 14% CP of DM diet without PBE (14%CP-PBE), (ii) AS with 14% CP of DM diet with PBE (14%CP + PBE), (iii) AS with 16% CP of DM diet without PBE (16%CP-PBE) and (iv) AS with 16% CP of DM diet with PBE (16%CP + PBE). PBE was sprayed on fresh alfalfa at a ratio of 500 ml/kg alfalfa DM to get the final concentration of 1% tannin as tannic acid equivalent on DM basis. Intake of CP was greater (p pistachio by-products tannins. Journal of Animal Physiology and Animal Nutrition © 2015 Blackwell Verlag GmbH.

  10. Hybrid Simulations of the Broadband Ground Motions for the 2008 MS8.0 Wenchuan, China, Earthquake

    Science.gov (United States)

    Yu, X.; Zhang, W.

    2012-12-01

    The Ms8.0 Wenchuan earthquake occurred on 12 May 2008 at 14:28 Beijing Time. It is the largest event happened in the mainland of China since the 1976, Mw7.6, Tangshan earthquake. Due to occur in the mountainous area, this great earthquake and the following thousands aftershocks also caused many other geological disasters, such as landslide, mud-rock flow and "quake lakes" which formed by landslide-induced reservoirs. These resulted in tremendous losses of life and property. Casualties numbered more than 80,000 people, and there were major economic losses. However, this earthquake is the first Ms 8 intraplate earthquake with good close fault strong motion coverage. Over four hundred strong motion stations of the National Strong Motion Observation Network System (NSMONS) recorded the mainshock. Twelve of them located within 20 km of the fault traces and another 33 stations located within 100 km. These observations, accompanying with the hundreds of GPS vectors and multiple ALOS INSAR images, provide an unprecedented opportunity to study the rupture process of such a great intraplate earthquake. In this study, we calculate broadband near-field ground motion synthetic waveforms of this great earthquake using a hybrid broadband ground-motion simulation methodology, which combines a deterministic approach at low frequencies (f < 1.0 Hz) with a theoretic Green's function calculation approach at high frequency ( ~ 10.0 Hz). The fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time that were obtained by an inversion kinematic source model. At the same time, based on the aftershock data, we analyze the site effects for the near-field stations. Frequency-dependent site-amplification values for each station are calculated using genetic algorithms. For the calculation of the synthetic waveforms, at first, we carry out simulations using the hybrid methodology for the frequency up to 10.0 Hz. Then, we consider for

  11. Radiation hardness assessment of the charge-integrating hybrid pixel detector JUNGFRAU 1.0 for photon science

    Energy Technology Data Exchange (ETDEWEB)

    Jungmann-Smith, J. H., E-mail: jsmith@magnet.fsu.edu; Bergamaschi, A.; Brückner, M.; Dinapoli, R.; Greiffenberg, D.; Jaggi, A.; Maliakal, D.; Mayilyan, D.; Mezza, D.; Mozzanica, A.; Ramilli, M.; Ruder, Ch.; Schädler, L.; Schmitt, B.; Shi, X.; Tinti, G. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Cartier, S. [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Institute for Biomedical Engineering, University and ETHZ, 8092 Zürich (Switzerland); Medjoubi, K. [Synchrotron Soleil, L’Orme des Merisiers, Saint-Aubin–BP 48, 91192 GIF-sur-Yvette Cedex (France)

    2015-12-15

    JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional hybrid pixel detector for photon science applications in free electron lasers, particularly SwissFEL, and synchrotron light sources. JUNGFRAU is an automatic gain switching, charge-integrating detector which covers a dynamic range of more than 10{sup 4} photons of an energy of 12 keV with a good linearity, uniformity of response, and spatial resolving power. The JUNGFRAU 1.0 application-specific integrated circuit (ASIC) features a 256 × 256 pixel matrix of 75 × 75 μm{sup 2} pixels and is bump-bonded to a 320 μm thick Si sensor. Modules of 2 × 4 chips cover an area of about 4 × 8 cm{sup 2}. Readout rates in excess of 2 kHz enable linear count rate capabilities of 20 MHz (at 12 keV) and 50 MHz (at 5 keV). The tolerance of JUNGFRAU to radiation is a key issue to guarantee several years of operation at free electron lasers and synchrotrons. The radiation hardness of JUNGFRAU 1.0 is tested with synchrotron radiation up to 10 MGy of delivered dose. The effect of radiation-induced changes on the noise, baseline, gain, and gain switching is evaluated post-irradiation for both the ASIC and the hybridized assembly. The bare JUNGFRAU 1.0 chip can withstand doses as high as 10 MGy with minor changes to its noise and a reduction in the preamplifier gain. The hybridized assembly, in particular the sensor, is affected by the photon irradiation which mainly shows as an increase in the leakage current. Self-healing of the system is investigated during a period of 11 weeks after the delivery of the radiation dose. Annealing radiation-induced changes by bake-out at 100 °C is investigated. It is concluded that the JUNGFRAU 1.0 pixel is sufficiently radiation-hard for its envisioned applications at SwissFEL and synchrotron beam lines.

  12. Synthesis and electrical characterization of low-temperature thermal-cured epoxy resin/functionalized silica hybrid-thin films for application as gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Na, Moonkyong, E-mail: nmk@keri.re.kr [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 (Korea, Republic of); Kang, Young Taec [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Department of Polymer Science and Engineering, Pusan National University, Busan, 609-735 (Korea, Republic of); Kim, Sang Cheol [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Kim, Eun Dong [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of)

    2013-07-31

    Thermal-cured hybrid materials were synthesized from homogenous hybrid sols of epoxy resins and organoalkoxysilane-functionalized silica. The chemical structures of raw materials and obtained hybrid materials were characterized using Fourier transform infrared spectroscopy. The thermal resistance of the hybrids was enhanced by hybridization. The interaction between epoxy matrix and the silica particles, which caused hydrogen bonding and van der Waals force was strengthened by organoalkoxysilane. The degradation temperature of the hybrids was improved by approximately 30 °C over that of the parent epoxy material. The hybrid materials were formed into uniformly coated thin films of about 50 nm-thick using a spin coater. An optimum mixing ratio was used to form smooth-surfaced hybrid films. The electrical property of the hybrid film was characterized, and the leakage current was found to be well below 10{sup −6} A cm{sup −2}. - Highlights: • Preparation of thermal-curable hybrid materials using epoxy resin and silica. • The thermal stability was enhanced through hybridization. • The insulation property of hybrid film was investigated as gate dielectrics.

  13. Photocatalytic oxidation removal of Hg"0 using ternary Ag/AgI-Ag_2CO_3 hybrids in wet scrubbing process under fluorescent light

    International Nuclear Information System (INIS)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    Highlights: • Ag/AgI-Ag_2CO_3 hybrids were employed for Hg"0 removal under fluorescent light. • Superoxide radical (·O_2"−) played a key role in Hg"0 removal. • NO exhibited a significant effect on Hg"0 removal in comparison to SO_2. • The mechanism for enhanced Hg"0 removal over Ag/AgI-Ag_2CO_3 was proposed. - Abstract: A series of ternary Ag/AgI-Ag_2CO_3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg"0 removal in a wet scrubbing reactor. The hybrids were characterized by N_2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg"0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg"0 removal. NO exhibited significant effect on Hg"0 removal in comparison to SO_2. Among these ternary Ag/AgI-Ag_2CO_3 hybrids, Ag/AgI(0.1)-Ag_2CO_3 showed the highest Hg"0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag_2CO_3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag"0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (·O_2"−) may play a key role in Hg"0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg"0 removal over Ag/AgI(0.1)-Ag_2CO_3 hybrid under fluorescent light was proposed.

  14. First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.

    Science.gov (United States)

    Bandura, Andrei V; Evarestov, Robert A

    2012-07-05

    The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. Copyright © 2012 Wiley Periodicals, Inc.

  15. Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2015-12-08

    Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 μL, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 × 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability. © 2015 American Chemical Society.

  16. Flexible, Transparent, Thickness-Controllable SWCNT/PEDOT:PSS Hybrid Films Based on Coffee-Ring Lithography for Functional Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong; Yang, Zhen Guo

    2015-01-01

    Flexible transparent conductive films (FTCFs) as the essential components of the next generation of functional circuits and devices are presently attracting more attention. Here, a new strategy has been demonstrated to fabricate thickness-controllable FTCFs through coffee ring lithography (CRL) of single-wall carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT:PSS) hybrid ink. The influence of ink concentration and volume on the thickness and size of hybrid film has been investigated systematically. Results show that the final FTCFs present a high performance, including a homogeneous thickness of 60-65 nm, a sheet resistance of 1.8 kohm/sq, a visible/infrared-range transmittance (79%, PET = 90%), and a dynamic mechanical property (>1000 cycle, much better than ITO film), respectively, when SWCNT concentration is 0.2 mg/mL, ink volume is 0.4 μL, drying at room temperature. Moreover, the benefits of these kinds of FTCFs have been verified through a full transparent, flexible noncontact sensing panel (3 × 4 sensing pixels) and a flexible battery-free wireless sensor based on a humidity sensing mechanism, showing excellent human/machine interaction with high sensitivity, good stability, and fast response/recovery ability. © 2015 American Chemical Society.

  17. Comparison of approximations in density functional theory calculations: Energetics and structure of binary oxides

    Science.gov (United States)

    Hinuma, Yoyo; Hayashi, Hiroyuki; Kumagai, Yu; Tanaka, Isao; Oba, Fumiyasu

    2017-09-01

    High-throughput first-principles calculations based on density functional theory (DFT) are a powerful tool in data-oriented materials research. The choice of approximation to the exchange-correlation functional is crucial as it strongly affects the accuracy of DFT calculations. This study compares performance of seven approximations, six of which are based on Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) with and without Hubbard U and van der Waals corrections (PBE, PBE+U, PBED3, PBED3+U, PBEsol, and PBEsol+U), and the strongly constrained and appropriately normed (SCAN) meta-GGA on the energetics and crystal structure of elementary substances and binary oxides. For the latter, only those with closed-shell electronic structures are considered, examples of which include C u2O , A g2O , MgO, ZnO, CdO, SnO, PbO, A l2O3 , G a2O3 , I n2O3 , L a2O3 , B i2O3 , Si O2 , Sn O2 , Pb O2 , Ti O2 , Zr O2 , Hf O2 , V2O5 , N b2O5 , T a2O5 , Mo O3 , and W O3 . Prototype crystal structures are selected from the Inorganic Crystal Structure Database (ICSD) and cation substitution is used to make a set of existing and hypothetical oxides. Two indices are proposed to quantify the extent of lattice and internal coordinate relaxation during a calculation. The former is based on the second invariant and determinant of the transformation matrix of basis vectors from before relaxation to after relaxation, and the latter is derived from shifts of internal coordinates of atoms in the unit cell. PBED3, PBEsol, and SCAN reproduce experimental lattice parameters of elementary substances and oxides well with few outliers. Notably, PBEsol and SCAN predict the lattice parameters of low dimensional structures comparably well with PBED3, even though these two functionals do not explicitly treat van der Waals interactions. SCAN gives formation enthalpies and Gibbs free energies closest to experimental data, with mean errors (MEs) of 0.01 and -0.04 eV, respectively, and root

  18. Structural, electronic and optical properties of silver delafossite oxides: A first-principles study with hybrid functional

    International Nuclear Information System (INIS)

    Kumar, Mukesh; Persson, Clas

    2013-01-01

    Ternary delafossite compounds are potential materials for optoelectronic devices. Employing a first-principles method, we calculate the structural, electronic, and optical properties of the silver based compounds AgMO 2 (M=Al, Ga or In), which crystallize in delafossite structure. Our calculations show that these AgMO 2 oxides have indirect band gaps and the gap energies are in the region of 1.6–3.0 eV whereas, the lowest direct band gap energies are estimated in the range of 2.6–4.3 eV. Furthermore, we find that AgMO 2 compounds exhibit a strong anisotropy for the dielectric function and absorption spectra. The absorption onset for these compounds occurs well above the band gap energies. Overall, we show that the hybrid functional improves the lattice parameters and band gap energies and the calculated values are in good agreement with the experimental values

  19. 16 CFR 0.7 - Delegation of functions.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Delegation of functions. 0.7 Section 0.7....7 Delegation of functions. The Commission, under the authority provided by Reorganization Plan No. 4... Commission, an individual Commissioner, an administrative law judge, or an employee or employee board, and...

  20. Hybrid strategies in nanolithography

    Energy Technology Data Exchange (ETDEWEB)

    Saavedra, Hector M; Mullen, Thomas J; Zhang Pengpeng; Dewey, Daniel C; Claridge, Shelley A; Weiss, Paul S [Department of Chemistry, The Pennsylvania State University, University Park, PA 16802 (United States)], E-mail: psw@cnsi.ucla.edu

    2010-03-15

    Hybrid nanoscale patterning strategies combine the registration and addressability of conventional lithographic techniques with the chemical and physical functionality enabled by intermolecular, electrostatic and/or biological interactions. This review aims to highlight and to provide a comprehensive description of recent developments in hybrid nanoscale patterning strategies that enhance existing lithographic techniques or can be used to fabricate functional chemical patterns that interact with their environment. These functional structures create new capabilities, such as the fabrication of physicochemical surfaces that can recognize and capture analytes from complex liquid or gaseous mixtures. The nanolithographic techniques we describe can be classified into three general areas: traditional lithography, soft lithography and scanning-probe lithography. The strengths and limitations of each hybrid patterning technique will be discussed, along with the current and potential applications of the resulting patterned, functional surfaces.

  1. Formation energies of rutile metal dioxides using density functional theory

    DEFF Research Database (Denmark)

    Martinez, Jose Ignacio; Hansen, Heine Anton; Rossmeisl, Jan

    2009-01-01

    We apply standard density functional theory at the generalized gradient approximation (GGA) level to study the stability of rutile metal oxides. It is well known that standard GGA exchange and correlation in some cases is not sufficient to address reduction and oxidation reactions. Especially...... and due to a more accurate description of exchange for this particular GGA functional compared to PBE. Furthermore, we would expect the self-interaction problem to be largest for the most localized d orbitals; that means the late 3d metals and since Co, Fe, Ni, and Cu do not form rutile oxides...

  2. Electron transport in polycyclic aromatic hydrocarbons/boron nitride hybrid structures: density functional theory combined with the nonequilibrium Green's function.

    Science.gov (United States)

    Panahi, S F K S; Namiranian, Afshin; Soleimani, Maryam; Jamaati, Maryam

    2018-02-07

    We investigate the electronic transport properties of two types of junction based on single polyaromatic hydrocarbons (PAHs) and PAHs embedded in boron nitride (h-BN) nanoribbons, using nonequilibrium Green's functions (NEGF) and density functional theory (DFT). In the PAH junctions, a Fano resonance line shape at the Fermi energy in the transport feature can be clearly seen. In hybrid junctions, structural asymmetries enable interactions between the electronic states, leading to observation of interface-based transport. Our findings reveal that the interface of PAH/h-BN strongly affects the transport properties of the structures.

  3. Evaluation of DFT methods for computing the interaction energies of homomolecular and heteromolecular dimers of monosubstituted benzene

    Science.gov (United States)

    Godfrey-Kittle, Andrew; Cafiero, Mauricio

    We present density functional theory (DFT) interaction energies for the sandwich and T-shaped conformers of substituted benzene dimers. The DFT functionals studied include TPSS, HCTH407, B3LYP, and X3LYP. We also include Hartree-Fock (HF) and second-order Møller-Plesset perturbation theory calculations (MP2), as well as calculations using a new functional, P3LYP, which includes PBE and HF exchange and LYP correlation. Although DFT methods do not explicitly account for the dispersion interactions important in the benzene-dimer interactions, we find that our new method, P3LYP, as well as HCTH407 and TPSS, match MP2 and CCSD(T) calculations much better than the hybrid methods B3LYP and X3LYP methods do.

  4. Optical Absorption Spectra and Electronic Properties of Symmetric and Asymmetric Squaraine Dyes for Use in DSSC Solar Cells: DFT and TD-DFT Studies

    Directory of Open Access Journals (Sweden)

    Reda M. El-Shishtawy

    2016-04-01

    Full Text Available The electronic absorption spectra, ground-state geometries and electronic structures of symmetric and asymmetric squaraine dyes (SQD1–SQD4 were investigated using density functional theory (DFT and time-dependent (TD-DFT density functional theory at the B3LYP/6-311++G** level. The calculated ground-state geometries reveal pronounced conjugation in these dyes. Long-range corrected time dependent density functionals Perdew, Burke and Ernzerhof (PBE, PBE1PBE (PBE0, and the exchange functional of Tao, Perdew, Staroverov, and Scuseria (TPSSh with 6-311++G** basis set were employed to examine optical absorption properties. In an extensive comparison between the optical data and DFT benchmark calculations, the BEP functional with 6-311++G** basis set was found to be the most appropriate in describing the electronic absorption spectra. The calculated energy values of lowest unoccupied molecular orbitals (LUMO were 3.41, 3.19, 3.38 and 3.23 eV for SQD1, SQD2, SQD3, and SQD4, respectively. These values lie above the LUMO energy (−4.26 eV of the conduction band of TiO2 nanoparticles indicating possible electron injection from the excited dyes to the conduction band of the TiO2 in dye-sensitized solar cells (DSSCs. Also, aromaticity computation for these dyes are in good agreement with the data obtained optically and geometrically with SQD4 as the highest aromatic structure. Based on the optimized molecular geometries, relative positions of the frontier orbitals, and the absorption maxima, we propose that these dyes are suitable components of photovoltaic DSSC devices.

  5. Magnetism in Sc-doped ZnO with zinc vacancies: A hybrid density functional and GGA + U approaches

    KAUST Repository

    Kanoun, Mohammed; Goumri-Said, Souraya; Schwingenschlö gl, Udo; Manchon, Aurelien

    2012-01-01

    We investigate the zinc vacancy effects on the electronic structures and magnetic properties of Sc-doped ZnO, by performing first-principles calculations within both GGA + U and Heyd-Scuseria-Ernzerhof hybrid functional methods. We find that Sc impurities stabilize considerably Zn vacancies. The electronic and magnetic analysis shows a half metallic ferromagnetic character with a total magnetic moment of 2.01 μ B. The magnetism mainly stems from the O 2p states around the Zn vacancies. Calculations with the hybrid density functional agree with the GGA + U results but give an accurate description of the electronic structure for pure ZnO and Sc-doped ZnO with Zn vacancies. © 2012 Elsevier B.V. All rights reserved.

  6. Magnetism in Sc-doped ZnO with zinc vacancies: A hybrid density functional and GGA + U approaches

    KAUST Repository

    Kanoun, Mohammed

    2012-04-01

    We investigate the zinc vacancy effects on the electronic structures and magnetic properties of Sc-doped ZnO, by performing first-principles calculations within both GGA + U and Heyd-Scuseria-Ernzerhof hybrid functional methods. We find that Sc impurities stabilize considerably Zn vacancies. The electronic and magnetic analysis shows a half metallic ferromagnetic character with a total magnetic moment of 2.01 μ B. The magnetism mainly stems from the O 2p states around the Zn vacancies. Calculations with the hybrid density functional agree with the GGA + U results but give an accurate description of the electronic structure for pure ZnO and Sc-doped ZnO with Zn vacancies. © 2012 Elsevier B.V. All rights reserved.

  7. Functional PMS2 hybrid alleles containing a pseudogene-specific missense variant trace back to a single ancient intrachromosomal recombination event.

    Science.gov (United States)

    Ganster, Christina; Wernstedt, Annekatrin; Kehrer-Sawatzki, Hildegard; Messiaen, Ludwine; Schmidt, Konrad; Rahner, Nils; Heinimann, Karl; Fonatsch, Christa; Zschocke, Johannes; Wimmer, Katharina

    2010-05-01

    Sequence exchange between PMS2 and its pseudogene PMS2CL, embedded in an inverted duplication on chromosome 7p22, has been reported to be an ongoing process that leads to functional PMS2 hybrid alleles containing PMS2- and PMS2CL-specific sequence variants at the 5'-and the 3'-end, respectively. The frequency of PMS2 hybrid alleles, their biological significance, and the mechanisms underlying their formation are largely unknown. Here we show that overall hybrid alleles account for one-third of 384 PMS2 alleles analyzed in individuals of different ethnic backgrounds. Depending on the population, 14-60% of hybrid alleles carry PMS2CL-specific sequences in exons 13-15, the remainder only in exon 15. We show that exons 13-15 hybrid alleles, named H1 hybrid alleles, constitute different haplotypes but trace back to a single ancient intrachromosomal recombination event with crossover. Taking advantage of an ancestral sequence variant specific for all H1 alleles we developed a simple gDNA-based polymerase chain reaction (PCR) assay that can be used to identify H1-allele carriers with high sensitivity and specificity (100 and 99%, respectively). Because H1 hybrid alleles harbor missense variant p.N775S of so far unknown functional significance, we assessed the H1-carrier frequency in 164 colorectal cancer patients. So far, we found no indication that the variant plays a major role with regard to cancer susceptibility. (c) 2010 Wiley-Liss, Inc.

  8. CD1d-unrestricted NKT cells are endowed with a hybrid function far superior than that of iNKT cells.

    Science.gov (United States)

    Farr, Alexander R; Wu, Weisheng; Choi, Bongkum; Cavalcoli, James D; Laouar, Yasmina

    2014-09-02

    Invariant natural killer T (iNKT) cells to date represent the best example of cells known to have a hybrid function, representing both innate and adaptive immunity. Shared phenotypic similarities with NK cells together with a rapid response to a cytokine stimulus and a productive TCR engagement are the features that underline the hybrid nature of iNKT cells. Using these criteria, we provide molecular and functional evidence demonstrating that CD1d-independent (CD1d(ind)) NKT cells, a population of CD1d-unrestricted NKT cells, are endowed with a hybrid function far superior to that of iNKT cells: (i) an extensive shared program with NK cells, (ii) a closer Euclidian distance with NK cells, and (iii) the ability to respond to innate stimuli (Poly:IC) with cytotoxic potential in the same manner as NK cells identify a hybrid feature in CD1d(ind)NKT cells that truly fulfills the dual function of an NK and a T cell. Our finding that CD1d(ind)NKT cells are programmed to act like NK cells in response to innate signals while being capable of adaptive responses is unprecedented, and thus might reemphasize CD1d-unrestricted NKT cells as a subset of lymphocytes that could affect biological processes of antimicrobial and tumor immunity in a unique way.

  9. Characterization of hybrid self-powered neutron detector under neutron irradiation

    CERN Document Server

    Nakamichi, M; Yamamura, C; Nakazawa, M; Kawamura, H

    2000-01-01

    To evaluate the irradiation behaviour of a blanket mock-up on in-pile functional test, it is necessary to measure the neutron flux change in the in-pile mock-up by a neutron detector, such as the self-powered neutron detector (SPND). With its small-sized emitter, which has high sensitivity and fast response time, SPND is an indispensable tool in order to measure the local neutron flux change. In the case of an in-pile functional test, it is necessary that response time is less than 1s and ratio of SPND output current is more than 0.3 of output current of SPND with Rh emitter. Therefore, a hybrid SPND with high sensitivity and fast response time was developed. This hybrid SPND used a hybrid emitter, i.e. Co cladded Pt-13%Rh.

  10. Oxygen defects in amorphous Al{sub 2}O{sub 3}: A hybrid functional study

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zhendong, E-mail: zhendong.guo@epfl.ch; Ambrosio, Francesco; Pasquarello, Alfredo [Chaire de Simulation à l' Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2016-08-08

    The electronic properties of the oxygen vacancy and interstitial in amorphous Al{sub 2}O{sub 3} are studied via ab initio molecular dynamics simulations and hybrid functional calculations. Our results indicate that these defects do not occur in amorphous Al{sub 2}O{sub 3}, due to structural rearrangements which assimilate the defect structure and cause a delocalization of the associated defect levels. The imbalance of oxygen leads to a nonstoichiometric compound in which the oxygen occurs in the form of O{sup 2–} ions. Intrinsic oxygen defects are found to be unable to trap excess electrons. For low Fermi energies, the formation of peroxy linkages is found to be favored leading to the capture of holes. The relative +2/0 defect levels occur at 2.5 eV from the valence band.

  11. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation.

    Science.gov (United States)

    Ma, Jin-Gang; Zhang, Cai-Rong; Gong, Ji-Jun; Wu, You-Zhi; Kou, Sheng-Zhong; Yang, Hua; Chen, Yu-Hong; Liu, Zi-Jiang; Chen, Hong-Shan

    2015-08-24

    Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs) to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  12. IT0: Discrete Math and Programming Logic Topics as a Hybrid Alternative to CS0

    Science.gov (United States)

    Martin, Nancy L.

    2015-01-01

    This paper describes the development of a hybrid introductory course for students in their first or second year of an information systems technologies degree program at a large Midwestern university. The course combines topics from discrete mathematics and programming logic and design, a unique twist on most introductory courses. The objective of…

  13. Preparation and toxicological assessment of functionalized carbon nanotube-polymer hybrids.

    Directory of Open Access Journals (Sweden)

    Nikos D Koromilas

    Full Text Available Novel Carbon Nanotube-Polymer Hybrids were synthesized as potential materials for the development of membranes for water treatment applications in the field of Membrane Bioreactors (MBRs. Due to the toxicological concerns regarding the use of nanomaterials in water treatment as well as the rising demand for safe drinking water to protect public health, we studied the functionalization of MWCNTs and Thin-MWCNTs as to control their properties and increase their ability of embedment into porous anisotropic polymeric membranes. Following the growth of the hydrophilic monomer on the surface of the properly functionalized CNTs, that act as initiator for the controlled radical polymerization (ATRP of sodium styrene sulfonate (SSNa, the antimicrobial quaternized phosphonium and ammonium salts were attached on CNTs-g-PSSNa through non-covalent bonding. In another approach the covalent attachment of quaternized ammonium polymeric moieties of acrylic acid-vinyl benzyl chloride copolymers with N,N-dimethylhexadecylamine (P(AA12-co-VBCHAM on functionalized CNTs has also been attempted. Finally, the toxicological assessment in terms of cell viability and cell morphological changes revealed that surface characteristics play a major role in the biological response of functionalized CNTs.

  14. 47 CFR 0.101 - Functions of the office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the office. 0.101 Section 0.101 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Communications Business Opportunities § 0.101 Functions of the office. (a) The Office of Communications Business...

  15. Luminescent hybrid materials functionalized with lanthanide ethylenodiaminotetraacetate complexes containing β-diketonate as antenna ligands

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Franklin P.; Costa, Israel F.; Espínola, José Geraldo P.; Faustino, Wagner M.; Moura, Jandeilson L. [Departamento de Química-Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil); Brito, Hermi F.; Paolini, Tiago B. [Departamento de Química Fundamental-Instituto de Química da Universidade de São Paulo, 05508-900 São Paulo, SP (Brazil); Felinto, Maria Cláudia F.C. [Instituto de Pesquisas energéticas e Nucleares-IPEN, 05508-900 São Paulo, SP (Brazil); Teotonio, Ercules E.S., E-mail: teotonioees@quimica.ufpb.br [Departamento de Química-Universidade Federal da Paraíba, 58051-970 João Pessoa, PB (Brazil)

    2016-02-15

    Three organic–inorganic hybrid materials based on silica gel functionalized with (3-aminopropyl)trimethoxysilane (APTS), [3-(2-aminoetilamino)-propil]-trimetoxissilano (DAPTS) and 3-[2-(2-aminoetilamino)etilamino] propiltrimetoxysilane (TAPTS) and subsequently modified with EDTA derivative were prepared by nonhomogeneous route and were then characterized. The resulting materials named SilXN-EDTA (X=1 for APTS, 2 for DAPTS and 3 for TAPTS) were used to obtain new lanthanide Ln{sup 3+}-β-diketonate (Ln{sup 3+}=Eu{sup 3+}, Gd{sup 3+} and Tb{sup 3+}) complexes covalently linked to the functionalized silica gel surfaces (named SilXN-EDTALn-dik, dik=tta, dbm, bzac and acac). The photophysical properties of the new luminescent materials were investigated and compared with those with similar system presenting water molecules coordinated to the lanthanide ions, SilXN-EDTALn-H{sub 2}O. The SilXN-EDTAEu-dik and SilXN-EDTATb-dik systems displayed characteristic red and green luminescence when excited by UV radiation. Furthermore, the quantitative results showed that the emission quantum efficiency (η), experimental intensity parameters Ω{sub 2} and Ω{sub 4}, and Einstein's emission coefficient (A{sub 0J}) of the SilXN-EDTAEu-dik materials were largely dependent on the ligands. Based on the luminescence data, the most efficient intramolecular energy transfer processes were found to the SilXN-EDTAEu-dik (dik: tta and dbm) and SilXN-EDTATb-acac materials, which exhibited more pure emission colors. These materials are promising red and green phosphors, respectively. - Highlights: • New highly luminescent hybrid materials containing lanthanide-EDTA complexes. • The effect of three silylanting agent on the adsorption and luminescent properties has been studied. • The luminescence sensitizing by different β-diketonate ligands have been investigated.

  16. 47 CFR 0.17 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.17 Section 0.17 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Legislative Affairs § 0.17 Functions of the Office. The Office of Legislative Affairs is directly responsible...

  17. 47 CFR 0.31 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.31 Section 0.31 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Engineering and Technology § 0.31 Functions of the Office. The Office of Engineering and Technology has the...

  18. 47 CFR 0.15 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.15 Section 0.15 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Media Relations § 0.15 Functions of the Office. (a) Enhance public understanding of and compliance with the...

  19. A Numerical Method for Lane-Emden Equations Using Hybrid Functions and the Collocation Method

    Directory of Open Access Journals (Sweden)

    Changqing Yang

    2012-01-01

    Full Text Available A numerical method to solve Lane-Emden equations as singular initial value problems is presented in this work. This method is based on the replacement of unknown functions through a truncated series of hybrid of block-pulse functions and Chebyshev polynomials. The collocation method transforms the differential equation into a system of algebraic equations. It also has application in a wide area of differential equations. Corresponding numerical examples are presented to demonstrate the accuracy of the proposed method.

  20. Prediction of core level binding energies in density functional theory: Rigorous definition of initial and final state contributions and implications on the physical meaning of Kohn-Sham energies.

    Science.gov (United States)

    Pueyo Bellafont, Noèlia; Bagus, Paul S; Illas, Francesc

    2015-06-07

    A systematic study of the N(1s) core level binding energies (BE's) in a broad series of molecules is presented employing Hartree-Fock (HF) and the B3LYP, PBE0, and LC-BPBE density functional theory (DFT) based methods with a near HF basis set. The results show that all these methods give reasonably accurate BE's with B3LYP being slightly better than HF but with both PBE0 and LCBPBE being poorer than HF. A rigorous and general decomposition of core level binding energy values into initial and final state contributions to the BE's is proposed that can be used within either HF or DFT methods. The results show that Koopmans' theorem does not hold for the Kohn-Sham eigenvalues. Consequently, Kohn-Sham orbital energies of core orbitals do not provide estimates of the initial state contribution to core level BE's; hence, they cannot be used to decompose initial and final state contributions to BE's. However, when the initial state contribution to DFT BE's is properly defined, the decompositions of initial and final state contributions given by DFT, with several different functionals, are very similar to those obtained with HF. Furthermore, it is shown that the differences of Kohn-Sham orbital energies taken with respect to a common reference do follow the trend of the properly calculated initial state contributions. These conclusions are especially important for condensed phase systems where our results validate the use of band structure calculations to determine initial state contributions to BE shifts.

  1. 47 CFR 0.151 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.151 Section 0.151 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Administrative Law Judges § 0.151 Functions of the Office. The Office of Administrative Law Judges consists of a...

  2. 47 CFR 0.11 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.11 Section 0.11 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Managing Director § 0.11 Functions of the Office. (a) The Managing Director is appointed by the Chairman with the...

  3. 47 CFR 0.13 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.13 Section 0.13 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Inspector General § 0.13 Functions of the Office. The Office of Inspector General is directly responsible to the...

  4. 47 CFR 0.21 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.21 Section 0.21 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of Strategic Planning and Policy Analysis § 0.21 Functions of the Office. The Office of Strategic Planning and Policy...

  5. 47 CFR 0.41 - Functions of the Office.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Functions of the Office. 0.41 Section 0.41 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization Office of General Counsel § 0.41 Functions of the Office. The Office of the General Counsel has the following duties and...

  6. Hybrid ICA-Seed-Based Methods for fMRI Functional Connectivity Assessment: A Feasibility Study

    Directory of Open Access Journals (Sweden)

    Robert E. Kelly

    2010-01-01

    Full Text Available Brain functional connectivity (FC is often assessed from fMRI data using seed-based methods, such as those of detecting temporal correlation between a predefined region (seed and all other regions in the brain; or using multivariate methods, such as independent component analysis (ICA. ICA is a useful data-driven tool, but reproducibility issues complicate group inferences based on FC maps derived with ICA. These reproducibility issues can be circumvented with hybrid methods that use information from ICA-derived spatial maps as seeds to produce seed-based FC maps. We report results from five experiments to demonstrate the potential advantages of hybrid ICA-seed-based FC methods, comparing results from regressing fMRI data against task-related a priori time courses, with “back-reconstruction” from a group ICA, and with five hybrid ICA-seed-based FC methods: ROI-based with (1 single-voxel, (2 few-voxel, and (3 many-voxel seed; and dual-regression-based with (4 single ICA map and (5 multiple ICA map seed.

  7. Genomic Prediction of Sunflower Hybrids Oil Content

    Directory of Open Access Journals (Sweden)

    Brigitte Mangin

    2017-09-01

    Full Text Available Prediction of hybrid performance using incomplete factorial mating designs is widely used in breeding programs including different heterotic groups. Based on the general combining ability (GCA of the parents, predictions are accurate only if the genetic variance resulting from the specific combining ability is small and both parents have phenotyped descendants. Genomic selection (GS can predict performance using a model trained on both phenotyped and genotyped hybrids that do not necessarily include all hybrid parents. Therefore, GS could overcome the issue of unknown parent GCA. Here, we compared the accuracy of classical GCA-based and genomic predictions for oil content of sunflower seeds using several GS models. Our study involved 452 sunflower hybrids from an incomplete factorial design of 36 female and 36 male lines. Re-sequencing of parental lines allowed to identify 468,194 non-redundant SNPs and to infer the hybrid genotypes. Oil content was observed in a multi-environment trial (MET over 3 years, leading to nine different environments. We compared GCA-based model to different GS models including female and male genomic kinships with the addition of the female-by-male interaction genomic kinship, the use of functional knowledge as SNPs in genes of oil metabolic pathways, and with epistasis modeling. When both parents have descendants in the training set, the predictive ability was high even for GCA-based prediction, with an average MET value of 0.782. GS performed slightly better (+0.2%. Neither the inclusion of the female-by-male interaction, nor functional knowledge of oil metabolism, nor epistasis modeling improved the GS accuracy. GS greatly improved predictive ability when one or both parents were untested in the training set, increasing GCA-based predictive ability by 10.4% from 0.575 to 0.635 in the MET. In this scenario, performing GS only considering SNPs in oil metabolic pathways did not improve whole genome GS prediction but

  8. DEVELOPMENT OF TOMATO HYBRIDS BASED ON FEMALE PARENTS FORMS WITH FUNCTIONAL MALE STERILITY

    Directory of Open Access Journals (Sweden)

    I. V. Uzun

    2016-01-01

    Full Text Available The rate of variability of functional male sterility (ps–2 depending on year of study, genotype and age of the plant is shown. The efficiency of the method of forced ejection of pollen from intact anthers to increase the degree of sterility is shown. The five tomato hybrids developed based on selected lines were submitted for the state variety trial of Moldova.

  9. Functionalized Graphene–Polyoxometalate Nanodots Assembly as “Organic–Inorganic” Hybrid Supercapacitors and Insights into Electrode/Electrolyte Interfacial Processes

    Directory of Open Access Journals (Sweden)

    Sanju Gupta

    2017-07-01

    Full Text Available The stable high-performance electrochemical electrodes consisting of supercapacitive reduced graphene oxide (rGO nanosheets decorated with pseudocapacitive polyoxometalates (phosphomolybdate acid-H3PMo12O40 (POM and phosphotungstic acid-H3PW12O40 (POW nanodots/nanoclusters are hydrothermally synthesized. The interactions between rGO and POM (and POW components create emergent “organic–inorganic” hybrids with desirable physicochemical properties (specific surface area, mechanical strength, diffusion, facile electron and ion transport enabled by molecularly bridged (covalently and electrostatically tailored interfaces for electrical energy storage. The synergistic hybridization between two electrochemical energy storage mechanisms, electrochemical double-layer from rGO and redox activity (faradaic of nanoscale POM (and POW nanodots, and the superior operating voltage due to high overpotential yielded converge yielding a significantly improved electrochemical performance. They include increase in specific capacitance from 70 F·g−1 for rGO to 350 F·g−1 for hybrid material with aqueous electrolyte (0.4 M sodium sulfate, higher current carrying capacity (>10 A·g−1 and excellent retention (94% resulting higher specific energy and specific power density. We performed scanning electrochemical microscopy to gain insights into physicochemical processes and quantitatively determine associated parameters (diffusion coefficient (D and heterogeneous electron transfer rate (kET at electrode/electrolyte interface besides mapping electrochemical (reactivity and electro-active site distribution. The experimental findings are attributed to: (1 mesoporous network and topologically multiplexed conductive pathways; (2 higher density of graphene edge plane sites; and (3 localized pockets of re-hybridized orbital engineered modulated band structure provided by polyoxometalates anchored chemically on functionalized graphene nanosheets, contribute toward

  10. What controls the hybridization thermodynamics of spherical nucleic acids?

    Science.gov (United States)

    Randeria, Pratik S; Jones, Matthew R; Kohlstedt, Kevin L; Banga, Resham J; Olvera de la Cruz, Monica; Schatz, George C; Mirkin, Chad A

    2015-03-18

    The hybridization of free oligonucleotides to densely packed, oriented arrays of DNA modifying the surfaces of spherical nucleic acid (SNA)-gold nanoparticle conjugates occurs with negative cooperativity; i.e., each binding event destabilizes subsequent binding events. DNA hybridization is thus an ever-changing function of the number of strands already hybridized to the particle. Thermodynamic quantification of this behavior reveals a 3 orders of magnitude decrease in the binding constant for the capture of a free oligonucleotide by an SNA conjugate as the fraction of pre-hybridized strands increases from 0 to ∼30%. Increasing the number of pre-hybridized strands imparts an increasing enthalpic penalty to hybridization that makes binding more difficult, while simultaneously decreasing the entropic penalty to hybridization, which makes binding more favorable. Hybridization of free DNA to an SNA is thus governed by both an electrostatic barrier as the SNA accumulates charge with additional binding events and an effect consistent with allostery, where hybridization at certain sites on an SNA modify the binding affinity at a distal site through conformational changes to the remaining single strands. Leveraging these insights allows for the design of conjugates that hybridize free strands with significantly higher efficiencies, some of which approach 100%.

  11. Hybrid platform. Economical hybrid drive for commercial vehicles; Hybrid Plattform. Wirtschaftlicher Hybridantrieb fuer Nutzfahrzeuge

    Energy Technology Data Exchange (ETDEWEB)

    Wallner, S.; Lamke, M.; Mohr, M.; Sedlacek, M.; Speck, F.D. [ZF Friedrichshafen AG, Friedrichshafen (Germany)

    2011-07-01

    Up to now, hybrid systems have been adapted to their specific requirements in the various applications for trucks, buses as well as mobile and building machines. From a technical point of view, this does indeed result in optimized hybrid drives for each single vehicle application, but due to small volumes, such single developments are critical from a business point of view. ZF Friedrichshafen AG is providing a solution to the technical and economical requirements of the cost-sensitive CV segment in the form of a modular CV parallel hybrid platform composed of a hybrid module system, an inverter, a battery system, and a hybrid software integrated into the overall vehicle. Thanks to the intelligent combination of assemblies and the use of as many identical parts as possible, platforms are realized which cover power ranges between 60 and 120 kW, voltage ranges between 350 and 650 V, and battery capacities between 2 and 4 kWh. The dimensions of the platform elements are such that integration into the diverse commercial vehicle applications is made easy. The hybrid software required for the vehicle-specific functions is also configurable for the mentioned CV applications. (orig.)

  12. A new hybrid genetic algorithm for optimizing the single and multivariate objective functions

    Energy Technology Data Exchange (ETDEWEB)

    Tumuluru, Jaya Shankar [Idaho National Laboratory; McCulloch, Richard Chet James [Idaho National Laboratory

    2015-07-01

    In this work a new hybrid genetic algorithm was developed which combines a rudimentary adaptive steepest ascent hill climbing algorithm with a sophisticated evolutionary algorithm in order to optimize complex multivariate design problems. By combining a highly stochastic algorithm (evolutionary) with a simple deterministic optimization algorithm (adaptive steepest ascent) computational resources are conserved and the solution converges rapidly when compared to either algorithm alone. In genetic algorithms natural selection is mimicked by random events such as breeding and mutation. In the adaptive steepest ascent algorithm each variable is perturbed by a small amount and the variable that caused the most improvement is incremented by a small step. If the direction of most benefit is exactly opposite of the previous direction with the most benefit then the step size is reduced by a factor of 2, thus the step size adapts to the terrain. A graphical user interface was created in MATLAB to provide an interface between the hybrid genetic algorithm and the user. Additional features such as bounding the solution space and weighting the objective functions individually are also built into the interface. The algorithm developed was tested to optimize the functions developed for a wood pelleting process. Using process variables (such as feedstock moisture content, die speed, and preheating temperature) pellet properties were appropriately optimized. Specifically, variables were found which maximized unit density, bulk density, tapped density, and durability while minimizing pellet moisture content and specific energy consumption. The time and computational resources required for the optimization were dramatically decreased using the hybrid genetic algorithm when compared to MATLAB's native evolutionary optimization tool.

  13. Vacancy formation in MoO3: hybrid density functional theory and photoemission experiments

    KAUST Repository

    Salawu, Omotayo Akande

    2016-09-29

    Molybdenum oxide (MoO3) is an important material that is being considered for numerous technological applications, including catalysis and electrochromism. In the present study, we apply hybrid density functional theory to investigate O and Mo vacancies in the orthorhombic phase. We determine the vacancy formation energies of different defect sites as functions of the electron chemical potential, addressing different charge states. In addition, we investigate the consequences of defects for the material properties. Ultraviolet photoemission spectroscopy is employed to study the valence band of stoichiometric and O defective MoO3. We show that O vacancies result in occupied in-gap states.

  14. Vacancy formation in MoO3: hybrid density functional theory and photoemission experiments

    KAUST Repository

    Salawu, Omotayo Akande; Chroneos, Alexander; Vasilopoulou, Maria; Kennou, Stella; Schwingenschlö gl, Udo

    2016-01-01

    Molybdenum oxide (MoO3) is an important material that is being considered for numerous technological applications, including catalysis and electrochromism. In the present study, we apply hybrid density functional theory to investigate O and Mo vacancies in the orthorhombic phase. We determine the vacancy formation energies of different defect sites as functions of the electron chemical potential, addressing different charge states. In addition, we investigate the consequences of defects for the material properties. Ultraviolet photoemission spectroscopy is employed to study the valence band of stoichiometric and O defective MoO3. We show that O vacancies result in occupied in-gap states.

  15. A Hybrid Imperative and Functional Molecular Mechanics Application

    Directory of Open Access Journals (Sweden)

    Thomas Deboni

    1996-01-01

    Full Text Available Molecular mechanics applications model the interactions among large ensembles of discrete particles. They are used where probabilistic methods are inadequate, such as drug chemistry. This methodology is difficult to parallelize with good performance, due to its poor locality, uneven partitions, and dynamic behavior. Imperative programs have been written that attempt this on shared and distributed memory machines. Given such a program, the computational kernel can be rewritten in Sisal, a functional programming language, and integrated with the rest of the imperative program under the Sisal Foreign Language Interface. This allows minimal effort and maximal return from parallelization work, and leaves the work appropriate to imperative implementation in its original form. We describe such an effort, focusing on the parts of the application that are appropriate for Sisal implementation, the specifics of mixed-language programming, and the complex performance behavior of the resulting hybrid code.

  16. Characterization of hybrid self-powered neutron detector under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nakamichi, M. E-mail: masaru@oarai.jaeri.go.jp; Nagao, Y.; Yamamura, C.; Nakazawa, M.; Kawamura, H

    2000-11-01

    To evaluate the irradiation behaviour of a blanket mock-up on in-pile functional test, it is necessary to measure the neutron flux change in the in-pile mock-up by a neutron detector, such as the self-powered neutron detector (SPND). With its small-sized emitter, which has high sensitivity and fast response time, SPND is an indispensable tool in order to measure the local neutron flux change. In the case of an in-pile functional test, it is necessary that response time is less than 1s and ratio of SPND output current is more than 0.3 of output current of SPND with Rh emitter. Therefore, a hybrid SPND with high sensitivity and fast response time was developed. This hybrid SPND used a hybrid emitter, i.e. Co cladded Pt-13%R000.

  17. Horseradish peroxidase-nanoclay hybrid particles of high functional and colloidal stability.

    Science.gov (United States)

    Pavlovic, Marko; Rouster, Paul; Somosi, Zoltan; Szilagyi, Istvan

    2018-08-15

    Highly stable dispersions of enzyme-clay nanohybrids of excellent horseradish peroxidase activity were developed. Layered double hydroxide nanoclay was synthesized and functionalized with heparin polyelectrolyte to immobilize the horseradish peroxidase enzyme. The formation of a saturated heparin layer on the platelets led to charge inversion of the positively charged bare nanoclay and to highly stable aqueous dispersions. Great affinity of the enzyme to the surface modified platelets resulted in strong horseradish peroxidase adsorption through electrostatic and hydrophobic interactions as well as hydrogen bonding network and prevented enzyme leakage from the obtained material. The enzyme kept its functional integrity upon immobilization and showed excellent activity in decomposition of hydrogen peroxide and oxidation of an aromatic compound in the test reactions. In addition, remarkable long term functional stability of the enzyme-nanoclay hybrid was observed making the developed colloidal system a promising antioxidant candidate in biomedical treatments and industrial processes. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Electrochemically Functionalized Seamless Three-Dimensional Graphene-Carbon Nanotube Hybrid for Direct Electron Transfer of Glucose Oxidase and Bioelectrocatalysis.

    Science.gov (United States)

    Terse-Thakoor, Trupti; Komori, Kikuo; Ramnani, Pankaj; Lee, Ilkeun; Mulchandani, Ashok

    2015-12-01

    Three-dimensional seamless chemical vapor deposition (CVD) grown graphene-carbon nanotubes (G-CNT) hybrid film has been studied for its potential in achieving direct electron transfer (DET) of glucose oxidase (GOx) and its bioelectrocatalytic activity in glucose detection. A two-step CVD method was employed for the synthesis of seamless G-CNT hybrid film where CNTs are grown on already grown graphene film on copper foil using iron as a catalyst. Physical characterization using SEM and TEM show uniform dense coverage of multiwall carbon nanotubes (MWCNT) grown directly on graphene with seamless contacts. The G-CNT hybrid film was electrochemically modified to introduce oxygenated functional groups for DET favorable immobilization of GOx. Pristine and electrochemically functionalized G-CNT film was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry, X-ray photoelectron-spectroscopy, and Raman spectroscopy. The DET between GOx and electrochemically oxidized G-CNT electrode was studied using cyclic voltammetry which showed a pair of well-defined and quasi-reversible redox peaks with a formal potential of -459 mV at pH 7 corresponding to the redox site of GOx. The constructed electrode detected glucose concentration over the clinically relevant range of 2-8 mM with the highest sensitivity of 19.31 μA/mM/cm(2) compared to reported composite hybrid electrodes of graphene oxide and CNTs. Electrochemically functionalized CVD grown seamless G-CNT structure used in this work has potential to be used for development of artificial mediatorless redox enzyme based biosensors and biofuel cells.

  19. Understanding and Calibrating Density-Functional-Theory Calculations Describing the Energy and Spectroscopy of Defect Sites in Hexagonal Boron Nitride.

    Science.gov (United States)

    Reimers, Jeffrey R; Sajid, A; Kobayashi, Rika; Ford, Michael J

    2018-03-13

    Defect states in 2-D materials present many possible uses but both experimental and computational characterization of their spectroscopic properties is difficult. We provide and compare results from 13 DFT and ab initio computational methods for up to 25 excited states of a paradigm system, the V N C B defect in hexagonal boron nitride (h-BN). Studied include: (i) potentially catastrophic effects for computational methods arising from the multireference nature of the closed-shell and open-shell states of the defect, which intrinsically involves broken chemical bonds, (ii) differing results from DFT and time-dependent DFT (TDDFT) calculations, (iii) comparison of cluster models to periodic-slab models of the defect, (iv) the starkly differing effects of nuclear relaxation on the various electronic states that control the widths of photoabsorption and photoemission spectra as broken bonds try to heal, (v) the effect of zero-point energy and entropy on free-energy differences, (vi) defect-localized and conduction/valence-band transition natures, and (vii) strategies needed to ensure that the lowest-energy state of a defect can be computationally identified. Averaged state-energy differences of 0.3 eV are found between CCSD(T) and MRCI energies, with thermal effects on free energies sometimes also being of this order. However, DFT-based methods can perform very poorly. Simple generalized-gradient functionals like PBE fail at the most basic level and should never be applied to defect states. Hybrid functionals like HSE06 work very well for excitations within the triplet manifold of the defect, with an accuracy equivalent to or perhaps exceeding the accuracy of the ab initio methods used. However, HSE06 underestimates triplet-state energies by on average of 0.7 eV compared to closed-shell singlet states, while open-shell singlet states are predicted to be too low in energy by 1.0 eV. This leads to misassignment of the ground state of the V N C B defect. Long

  20. Novel nuclear localization and potential function of insulin-like growth factor-1 receptor/insulin receptor hybrid in corneal epithelial cells.

    Directory of Open Access Journals (Sweden)

    Yu-Chieh Wu

    Full Text Available BACKGROUND: Type I insulin-like growth factor receptor (IGF-1R and insulin receptor (INSR are highly homologous molecules, which can heterodimerize to form an IGF-1R/INSR hybrid (Hybrid-R. The presence and biological significance of the Hybrid-R in human corneal epithelium has not yet been established. In addition, while nuclear localization of IGF-1R was recently reported in cancer cells and human corneal epithelial cells, the function and profile of nuclear IGF-1R is unknown. In this study, we characterized the nuclear localization and function of the Hybrid-R and the role of IGF-1/IGF-1R and Hybrid-R signaling in the human corneal epithelium. METHODOLOGY/PRINCIPLE FINDINGS: IGF-1-mediated signaling and cell growth were examined in a human telomerized corneal epithelial (hTCEpi cell line using co-immunoprecipitation, immunoblotting and cell proliferation assays. The presence of Hybrid-R in hTCEpi and primary cultured human corneal epithelial cells was confirmed by immunofluorescence and reciprocal immunoprecipitation of whole cell lysates. We found that IGF-1 stimulated Akt and promoted cell growth through IGF-1R activation, which was independent of the Hybrid-R. The presence of Hybrid-R, but not IGF-1R/IGF-1R, was detected in nuclear extracts. Knockdown of INSR by small interfering RNA resulted in depletion of the INSR/INSR and preferential formation of Hybrid-R. Chromatin-immunoprecipitation sequencing assay with anti-IGF-1R or anti-INSR was subsequently performed to identify potential genomic targets responsible for critical homeostatic regulatory pathways. CONCLUSION/SIGNIFICANCE: In contrast to previous reports on nuclear localized IGF-1R, this is the first report identifying the nuclear localization of Hybrid-R in an epithelial cell line. The identification of a nuclear Hybrid-R and novel genomic targets suggests that IGF-1R traffics to the nucleus as an IGF-1R/INSR heterotetrameric complex to regulate corneal epithelial homeostatic

  1. Pair-Wise and Many-Body Dispersive Interactions Coupled to an Optimally Tuned Range-Separated Hybrid Functional.

    Science.gov (United States)

    Agrawal, Piyush; Tkatchenko, Alexandre; Kronik, Leeor

    2013-08-13

    We propose a nonempirical, pair-wise or many-body dispersion-corrected, optimally tuned range-separated hybrid functional. This functional retains the advantages of the optimal-tuning approach in the prediction of the electronic structure. At the same time, it gains accuracy in the prediction of binding energies for dispersively bound systems, as demonstrated on the S22 and S66 benchmark sets of weakly bound dimers.

  2. Fine-scale genetic mapping of a hybrid sterility factor between Drosophila simulans and D. mauritiana: the varied and elusive functions of "speciation genes".

    Science.gov (United States)

    Araripe, Luciana O; Montenegro, Horácio; Lemos, Bernardo; Hartl, Daniel L

    2010-12-14

    Hybrid male sterility (HMS) is a usual outcome of hybridization between closely related animal species. It arises because interactions between alleles that are functional within one species may be disrupted in hybrids. The identification of genes leading to hybrid sterility is of great interest for understanding the evolutionary process of speciation. In the current work we used marked P-element insertions as dominant markers to efficiently locate one genetic factor causing a severe reduction in fertility in hybrid males of Drosophila simulans and D. mauritiana. Our mapping effort identified a region of 9 kb on chromosome 3, containing three complete and one partial coding sequences. Within this region, two annotated genes are suggested as candidates for the HMS factor, based on the comparative molecular characterization and public-source information. Gene Taf1 is partially contained in the region, but yet shows high polymorphism with four fixed non-synonymous substitutions between the two species. Its molecular functions involve sequence-specific DNA binding and transcription factor activity. Gene agt is a small, intronless gene, whose molecular function is annotated as methylated-DNA-protein-cysteine S-methyltransferase activity. High polymorphism and one fixed non-synonymous substitution suggest this is a fast evolving gene. The gene trees of both genes perfectly separate D. simulans and D. mauritiana into monophyletic groups. Analysis of gene expression using microarray revealed trends that were similar to those previously found in comparisons between whole-genome hybrids and parental species. The identification following confirmation of the HMS candidate gene will add another case study leading to understanding the evolutionary process of hybrid incompatibility.

  3. Influence of Stress Shape Function on Analysis of Contact Problem Using Hybrid Photoelasticity

    International Nuclear Information System (INIS)

    Shin, Dongchul; Hawong, Jaisug

    2013-01-01

    In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work

  4. Improving the specific energy of Li-Ion capacitor laminate cell using hybrid activated Carbon/LiNi0.5Co0.2Mn0.3O2 as positive electrodes

    Science.gov (United States)

    Hagen, M.; Cao, W. J.; Shellikeri, A.; Adams, D.; Chen, X. J.; Brandt, W.; Yturriaga, S. R.; Wu, Q.; Read, J. A.; Jow, T. R.; Zheng, J. P.

    2018-03-01

    In this work, we investigated the performance impact of LiNi0.5Co0.2Mn0.3O2 (NMC) as an additive to activated carbon (AC) electrodes within a high-performance Li-ion capacitor (LIC) fabricated with activated carbon positive electrodes (PEs) and hard carbon negative electrodes (NEs) having lithium thin films as Li sources loaded on the surface of the negative electrodes. The NMC additive impact in initial testing showed an increase in specific energy of the LIC of nearly 50.5% with a 32% maximum specific power loss. Contrary to its typical low rate battery decay at high rate cycling the cell having a hybrid PE is still able to maintain over 90% capacity at a 0.7C rate after 11,000 cycles at rate of 18C and an additional 9000 cycles at a rate of 36C. We conclude at high rate cycling minimal impacts occurs to the NMC properties which can be seen with low rate intercepts.

  5. First-principles investigations on the mechanical, thermal, electronic, and optical properties of the defect perovskites Cs2Sn X 6 ( X = Cl, Br, I)

    International Nuclear Information System (INIS)

    Huang Hai-Ming; Jiang Zhen-Yi; Luo Shi-Jun

    2017-01-01

    The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs 2 Sn X 6 ( X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hybrid functional. The optic band gaps based on HSE06 are 3.83 eV for Cs 2 SnCl 6 , 2.36 eV for Cs 2 SnBr 6 , and 0.92 eV for Cs 2 SnI 6 , which agree with the experimental results. The Cs 2 SnCl 6 , Cs 2 SnBr 6 , and Cs 2 SnI 6 are mechanically stable and they are all anisotropic and ductile in nature. Electronic structures calculations show that the conduction band consists mainly of hybridization between the halogen p orbitals and Sn 5s orbitals, whereas the valence band is composed of the halogen p orbitals. Optic properties indicate that these three compounds exhibit good optical absorption in the ultraviolet region, and the absorption spectra red shift with the increase in the number of halogen atoms. The defect perovskites are good candidates for probing the lead-free and high power conversion efficiency of solar cells. (paper)

  6. Electronic properties of B and Al doped graphane: A hybrid density functional study

    Science.gov (United States)

    Mapasha, R. E.; Igumbor, E.; Andriambelaza, N. F.; Chetty, N.

    2018-04-01

    Using a hybrid density functional theory approach parametrized by Heyd, Scuseria and Ernzerhof (HSE06 hybrid functional), we study the energetics, structural and electronic properties of a graphane monolayer substitutionally doped with the B (BCH) and Al (AlCH) atoms. The BCH defect can be integrated within a graphane monolayer at a relative low formation energy, without major structural distortions and symmetry breaking. The AlCH defect relaxes outward of the monolayer and breaks the symmetry. The density of states plots indicate that BCH doped graphane monolayer is a wide band gap semiconductor, whereas the AlCH defect introduces the spin dependent mid gap states at the vicinity of the Fermi level, revealing a metallic character with the pronounced magnetic features. We further examine the response of the Al dependent spin states on the multiple charge states doping. We find that the defect formation energy, structural and electronic properties can be altered via charge state modulation. The +1 charge doping opens an energy band gap of 1.75 eV. This value corresponds to the wavelength in the visible spectrum, suggesting an ideal material for solar cell absorbers. Our study fine tunes the graphane band gap through the foreign atom doping as well as via defect charge state modulation.

  7. Metal-insulator transition at the LaAlO3/SrTiO3 interface revisited: A hybrid functional study

    KAUST Repository

    Cossu, Fabrizio; Eyert, V.; Schwingenschlö gl, Udo

    2013-01-01

    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

  8. A highly conductive, non-flammable polymer–nanoparticle hybrid electrolyte

    KAUST Repository

    Agrawal, Akanksha

    2015-01-01

    © 2015 The Royal Society of Chemistry. We report on the physical properties of lithium-ion conducting nanoparticle-polymer hybrid electrolytes created by dispersing bidisperse mixtures of polyethylene glycol (PEG)-functionalized silica nanoparticles in an aprotic liquid host. At high particle contents, we find that the ionic conductivity is a non-monotonic function of the fraction of larger particles xL in the mixtures, and that for the nearly symmetric case xL ≈ 0.5 (i.e. equal volume fraction of small and large particles), the room temperature ionic conductivity is nearly ten-times larger than in similar nanoparticle hybrid electrolytes comprised of the pure small (xL ≈ 0) or large (xL ≈ 1) particle components. Complementary trends are seen in the activation energy for ion migration and effective tortuosity of the electrolytes, which both exhibit minima near xL ≈ 0.5. Characterization of the electrolytes by dynamic rheology reveals that the maximum conductivity coincides with a distinct transition in soft glassy properties from a jammed to partially jammed and back to jammed state, as the fraction of large particles is increased from 0 to 1. This finding implies that the conductivity enhancement arises from purely entropic loss of correlation between nanoparticle centers arising from particle size dispersity. As a consequence of these physics, it is now possible to create hybrid electrolytes with MPa elastic moduli and mS cm-1 ionic conductivity levels at room temperature using common aprotic liquid media as the electrolyte solvent. Remarkably, we also find that even in highly flammable liquid media, the bidisperse nanoparticle hybrid electrolytes can be formulated to exhibit low or no flammability without compromising their favorable room temperature ionic conductivity and mechanical properties.

  9. Ab initio, density functional theory, and continuum solvation model prediction of the product ratio in the S(N)2 reaction of NO2(-) with CH3CH2Cl and CH3CH2Br in DMSO solution.

    Science.gov (United States)

    Westphal, Eduard; Pliego, Josefredo R

    2007-10-11

    The reaction pathways for the interaction of the nitrite ion with ethyl chloride and ethyl bromide in DMSO solution were investigated at the ab initio level of theory, and the solvent effect was included through the polarizable continuum model. The performance of BLYP, GLYP, XLYP, OLYP, PBE0, B3PW91, B3LYP, and X3LYP density functionals has been tested. For the ethyl bromide case, our best ab initio calculations at the CCSD(T)/aug-cc-pVTZ level predicts product ratio of 73% and 27% for nitroethane and ethyl nitrite, respectively, which can be compared with the experimental values of 67% and 33%. This translates to an error in the relative DeltaG* of only 0.17 kcal mol(-1). No functional is accurate (deviation X3LYP functional presents the best performance with deviation 0.82 kcal mol(-1). The present problem should be included in the test set used for the evaluation of new functionals.

  10. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects

    KAUST Repository

    Zhang, Zhenkui; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    We examine the effects of several intrinsic defects on the magnetic behavior of ZnS nanostructures using hybrid density functional theory to gain insights into d0 ferromagnetism. Previous studies have predicted that the magnetism is due to a

  11. 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

  12. Fine-scale genetic mapping of a hybrid sterility factor between Drosophila simulans and D. mauritiana: the varied and elusive functions of "speciation genes"

    Directory of Open Access Journals (Sweden)

    Lemos Bernardo

    2010-12-01

    Full Text Available Abstract Background Hybrid male sterility (HMS is a usual outcome of hybridization between closely related animal species. It arises because interactions between alleles that are functional within one species may be disrupted in hybrids. The identification of genes leading to hybrid sterility is of great interest for understanding the evolutionary process of speciation. In the current work we used marked P-element insertions as dominant markers to efficiently locate one genetic factor causing a severe reduction in fertility in hybrid males of Drosophila simulans and D. mauritiana. Results Our mapping effort identified a region of 9 kb on chromosome 3, containing three complete and one partial coding sequences. Within this region, two annotated genes are suggested as candidates for the HMS factor, based on the comparative molecular characterization and public-source information. Gene Taf1 is partially contained in the region, but yet shows high polymorphism with four fixed non-synonymous substitutions between the two species. Its molecular functions involve sequence-specific DNA binding and transcription factor activity. Gene agt is a small, intronless gene, whose molecular function is annotated as methylated-DNA-protein-cysteine S-methyltransferase activity. High polymorphism and one fixed non-synonymous substitution suggest this is a fast evolving gene. The gene trees of both genes perfectly separate D. simulans and D. mauritiana into monophyletic groups. Analysis of gene expression using microarray revealed trends that were similar to those previously found in comparisons between whole-genome hybrids and parental species. Conclusions The identification following confirmation of the HMS candidate gene will add another case study leading to understanding the evolutionary process of hybrid incompatibility.

  13. Output Tracking Control of Switched Hybrid Systems: A Fliess Functional Expansion Approach

    Directory of Open Access Journals (Sweden)

    Fenghua He

    2013-01-01

    Full Text Available The output tracking problem is investigated for a nonlinear affine system with multiple modes of continuous control inputs. We convert the family of nonlinear affine systems under consideration into a switched hybrid system by introducing a multiple-valued logic variable. The Fliess functional expansion is adopted to express the input and output relationship of the switched hybrid system. The optimal switching control is determined for a multiple-step output tracking performance index. The proposed approach is applied to a multitarget tracking problem for a flight vehicle aiming for one real target with several decoys flying around it in the terminal guidance course. These decoys appear as apparent targets and have to be distinguished with the approaching of the flight vehicle. The guidance problem of one flight vehicle versus multiple apparent targets should be considered if no large miss distance might be caused due to the limitation of the flight vehicle maneuverability. The target orientation at each time interval is determined. Simulation results show the effectiveness of the proposed method.

  14. Hybrid image and blood sampling input function for quantification of small animal dynamic PET data

    International Nuclear Information System (INIS)

    Shoghi, Kooresh I.; Welch, Michael J.

    2007-01-01

    We describe and validate a hybrid image and blood sampling (HIBS) method to derive the input function for quantification of microPET mice data. The HIBS algorithm derives the peak of the input function from the image, which is corrected for recovery, while the tail is derived from 5 to 6 optimally placed blood sampling points. A Bezier interpolation algorithm is used to link the rightmost image peak data point to the leftmost blood sampling point. To assess the performance of HIBS, 4 mice underwent 60-min microPET imaging sessions following a 0.40-0.50-mCi bolus administration of 18 FDG. In total, 21 blood samples (blood-sampled plasma time-activity curve, bsPTAC) were obtained throughout the imaging session to compare against the proposed HIBS method. MicroPET images were reconstructed using filtered back projection with a zoom of 2.75 on the heart. Volumetric regions of interest (ROIs) were composed by drawing circular ROIs 3 pixels in diameter on 3-4 transverse planes of the left ventricle. Performance was characterized by kinetic simulations in terms of bias in parameter estimates when bsPTAC and HIBS are used as input functions. The peak of the bsPTAC curve was distorted in comparison to the HIBS-derived curve due to temporal limitations and delay in blood sampling, which affected the rates of bidirectional exchange between plasma and tissue. The results highlight limitations in using bsPTAC. The HIBS method, however, yields consistent results, and thus, is a substitute for bsPTAC

  15. Combined experimental–theoretical study of the optoelectronic properties of non-stoichiometric pyrochlore bismuth titanate

    KAUST Repository

    Noureldine, Dalal

    2015-10-27

    A combination of experimental and computational methods was applied to investigate the crystal structure and optoelectronic properties of the non-stoichiometric pyrochlore Bi2−xTi2O7−1.5x. The detailed experimental protocol for both powder and thin-film material synthesis revealed that a non-stoichiometric Bi2−xTi2O7−1.5x structure with an x value of ∼0.25 is the primary product, consistent with the thermodynamic stability of the defect-containing structure computed using density functional theory (DFT). The approach of density functional perturbation theory (DFPT) was used along with the standard GGA PBE functional and the screened Coulomb hybrid HSE06 functional, including spin–orbit coupling, to investigate the electronic structure, the effective electron and hole masses, the dielectric constant, and the absorption coefficient. The calculated values for these properties are in excellent agreement with the measured values, corroborating the overall analysis. This study indicates potential applications of bismuth titanate as a wide-bandgap material, e.g., as a substitute for TiO2 in dye-sensitized solar cells and UV-light-driven photocatalysis.

  16. The Electronic Structures and Optical Properties of Alkaline-Earth Metals Doped Anatase TiO2: A Comparative Study of Screened Hybrid Functional and Generalized Gradient Approximation

    Directory of Open Access Journals (Sweden)

    Jin-Gang Ma

    2015-08-01

    Full Text Available Alkaline-earth metallic dopant can improve the performance of anatase TiO2 in photocatalysis and solar cells. Aiming to understand doping mechanisms, the dopant formation energies, electronic structures, and optical properties for Be, Mg, Ca, Sr, and Ba doped anatase TiO2 are investigated by using density functional theory calculations with the HSE06 and PBE functionals. By combining our results with those of previous studies, the HSE06 functional provides a better description of electronic structures. The calculated formation energies indicate that the substitution of a lattice Ti with an AEM atom is energetically favorable under O-rich growth conditions. The electronic structures suggest that, AEM dopants shift the valence bands (VBs to higher energy, and the dopant-state energies for the cases of Ca, Sr, and Ba are quite higher than Fermi levels, while the Be and Mg dopants result into the spin polarized gap states near the top of VBs. The components of VBs and dopant-states support that the AEM dopants are active in inter-band transitions with lower energy excitations. As to optical properties, Ca/Sr/Ba are more effective than Be/Mg to enhance absorbance in visible region, but the Be/Mg are superior to Ca/Sr/Ba for the absorbance improvement in near-IR region.

  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. A first principles study of the mechanical, electronic, and vibrational properties of lead oxide

    Science.gov (United States)

    Zhuravlev, Yu. N.; Korabel'nikov, D. V.

    2017-11-01

    The first principles study of the crystal structure, chemical bonds, elastic and mechanical properties, electron energy band structure and density, and normal long-wave vibrations of nine phases of lead monoxide, dioxide, and tetraoxide has been performed under normal and external pressure within the framework of density functional theory (DFT) with the Perdew-Becke-Ernzerhof (PBE) gradient exchange-correlation functional and its hybrid version with a 25-% Hartree-Fock (HF) exchange contribution in the basis of localized atom orbitals. The behavior of physical parameters has been studied using the cold four- and threeparameter equations of state. The parameters of the crystal structures are in satisfactory agreement with experimental data, and elastic constants indicate their mechanical stability and anisotropy in the elastic properties. The elasticity, shear, and Young moduli, hardness, acoustic velocities, and Debye temperature of dioxide on the one hand and monoxide and tetraoxide on the other hand appreciably differ from each other. The difference between electron properties may be explained by the character of hybridization in the upper filled and lower empty energy bands as evident from the density of states. In monoxide, the indirect band gap width decreases with increasing pressure at a rate of 0.16 eV/GPa, and the direct band gap width increases at a rate of 0.13 eV/GPa. To identify crystalline phases, the frequencies and intensities of long-wave modes active in IR and Raman spectra have been calculated.

  19. Near infrared optical biosensor based on peptide functionalized single-walled carbon nanotubes hybrids for 2,4,6-trinitrotoluene (TNT) explosive detection.

    Science.gov (United States)

    Wang, Jin

    2018-06-01

    A near infrared (NIR) optical biosensor based on peptide functionalized single-walled carbon nanotubes (SWCNTs) hybrids for 2,4,6-trinitrotoluene (TNT) explosive detection was developed. The TNT binding peptide was directly anchored on the sidewall of the SWCNTs using the π-π interaction between the aromatic amino acids and SWCNTs, forming the peptide-SWCNTs hybrids for near infrared absorption spectra measurement. The evidence of the morphology of peptide-SWCNTs hybrids was obtained using atomic force microscopy (AFM). The results demonstrated that peptide-SWCNTs hybrids based NIR optical biosensor exhibited sensitive and highly selective for TNT explosive determination, addressing a promising optical biosensor for security application. Copyright © 2018. Published by Elsevier Inc.

  20. The screening effects of the screened exchange hybrid functional in surface systems: A case study on the CO/Pt(111) problem

    Energy Technology Data Exchange (ETDEWEB)

    Li, H., E-mail: li-huanglong@mail.tsinghua.edu.cn [Department of Precision Instrument, Tsinghua University, Beijing, 100084 (China); Gillen, R. [Institut für Festkörperphysik. Technische Universität Berlin. Hardenbergstr. 36, 10623 Berlin (Germany); Robertson, J., E-mail: jr214@cam.ac.uk [Engineering Department, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2016-06-15

    The screened exchange (sX) hybrid functional has been widely used in computational material science. Although it has widely been studied in bulk systems, less is known about its functional behavior in surface systems which are crucial to many technologies such as materials synthesis and nano-electronic devices. Assessing the screening dependent functional behaviors in the surface systems is therefore important for its application in such systems. In this work, we investigate the screening effects of the sX in CO adsorption on Pt(111) surface. The differences between the sX and Heyd-Scuseria-Ernzerhof (HSE06) hybrid functionals, and the effects of screening parameters are studied. The screening has two effects: first, the HOMO-LUMO gap is screening dependent. This affects the site preference most significantly. In this work, atop adsorption of CO/Pt(111) is predicted by the hybrid functionals with screened exchange potential. The sX(1.44) gives the largest HOMO-LUMO gap for the isolated CO molecule. The adsorption energy difference between the atop and fcc site is also the largest by the sX(1.44) which is explained by the reduced metal d states to the CO 2π* state back-donation, with stronger effect for the fcc adsorption than for the atop adsorption; second, the adsorption energy is screening dependent. This can be seen by comparing the sX(2.38) and HSE06 which have different screening strengths. They show similar surface band structures for the CO adsorption but different adsorption energies, which is explained by the stronger CO 5σ state to the metal d states donation or the effectively screened Pauli repulsion. This work underlines the screening strength as a main difference between sX and HSE06, as well as an important hybrid functional parameter for surface calculation.

  1. Genomic Prediction of Barley Hybrid Performance

    Directory of Open Access Journals (Sweden)

    Norman Philipp

    2016-07-01

    Full Text Available Hybrid breeding in barley ( L. offers great opportunities to accelerate the rate of genetic improvement and to boost yield stability. A crucial requirement consists of the efficient selection of superior hybrid combinations. We used comprehensive phenotypic and genomic data from a commercial breeding program with the goal of examining the potential to predict the hybrid performances. The phenotypic data were comprised of replicated grain yield trials for 385 two-way and 408 three-way hybrids evaluated in up to 47 environments. The parental lines were genotyped using a 3k single nucleotide polymorphism (SNP array based on an Illumina Infinium assay. We implemented ridge regression best linear unbiased prediction modeling for additive and dominance effects and evaluated the prediction ability using five-fold cross validations. The prediction ability of hybrid performances based on general combining ability (GCA effects was moderate, amounting to 0.56 and 0.48 for two- and three-way hybrids, respectively. The potential of GCA-based hybrid prediction requires that both parental components have been evaluated in a hybrid background. This is not necessary for genomic prediction for which we also observed moderate cross-validated prediction abilities of 0.51 and 0.58 for two- and three-way hybrids, respectively. This exemplifies the potential of genomic prediction in hybrid barley. Interestingly, prediction ability using the two-way hybrids as training population and the three-way hybrids as test population or vice versa was low, presumably, because of the different genetic makeup of the parental source populations. Consequently, further research is needed to optimize genomic prediction approaches combining different source populations in barley.

  2. Energy vs. density on paths toward more exact density functionals.

    Science.gov (United States)

    Kepp, Kasper P

    2018-03-14

    Recently, the progression toward more exact density functional theory has been questioned, implying a need for more formal ways to systematically measure progress, i.e. a "path". Here I use the Hohenberg-Kohn theorems and the definition of normality by Burke et al. to define a path toward exactness and "straying" from the "path" by separating errors in ρ and E[ρ]. A consistent path toward exactness involves minimizing both errors. Second, a suitably diverse test set of trial densities ρ' can be used to estimate the significance of errors in ρ without knowing the exact densities which are often inaccessible. To illustrate this, the systems previously studied by Medvedev et al., the first ionization energies of atoms with Z = 1 to 10, the ionization energy of water, and the bond dissociation energies of five diatomic molecules were investigated using CCSD(T)/aug-cc-pV5Z as benchmark at chemical accuracy. Four functionals of distinct designs was used: B3LYP, PBE, M06, and S-VWN. For atomic cations regardless of charge and compactness up to Z = 10, the energy effects of the different ρ are energy-wise insignificant. An interesting oscillating behavior in the density sensitivity is observed vs. Z, explained by orbital occupation effects. Finally, it is shown that even large "normal" problems such as the Co-C bond energy of cobalamins can use simpler (e.g. PBE) trial densities to drastically speed up computation by loss of a few kJ mol -1 in accuracy. The proposed method of using a test set of trial densities to estimate the sensitivity and significance of density errors of functionals may be useful for testing and designing new balanced functionals with more systematic improvement of densities and energies.

  3. Course on hybrid calculation

    International Nuclear Information System (INIS)

    Weill, J.; Tellier; Bonnemay; Craigne; Chareton; Di Falco

    1969-02-01

    After a definition of hybrid calculation (combination of analogue and digital calculation) with a distinction between series and parallel hybrid computing, and a description of a hybrid computer structure and of task sharing between computers, this course proposes a description of hybrid hardware used in Saclay and Cadarache computing centres, and of operations performed by these systems. The next part addresses issues related to programming languages and software. The fourth part describes how a problem is organised for its processing on these computers. Methods of hybrid analysis are then addressed: resolution of optimisation problems, of partial differential equations, and of integral equations by means of different methods (gradient, maximum principle, characteristics, functional approximation, time slicing, Monte Carlo, Neumann iteration, Fischer iteration)

  4. Hybrid density functional study on the mechanism for the enhanced photocatalytic properties of the ultrathin hybrid layered nanocomposite g-C3N4/BiOCl

    Science.gov (United States)

    Yao, Wenzhi; Zhang, Jihua; Wang, Yuanxu; Ren, Fengzhu

    2018-03-01

    To investigate the origin of the high photocatalytic performance of experimentally synthesized g-C3N4/ BiOCl, we studied its geometry structure, electronic structure, and photocatalytic properties by means of hybrid density-functional theory (DFT). The calculated band alignment of g-C3N4 and few-layer BiOCl sheets clearly shows that g-C3N4/ BiOCl is a standard type-II nanocomposite. The density of states, Bader charge, partial charge density, charge density difference, and the effective masses show that electron-hole pair can be effectively separated in the g-C3N4/BiOCl interface. The calculated absorption coefficients indicate an obvious redshift of the absorption edge. The band gap of g-C3N4/BiOCl can be modulated by external electric field, and a semiconductor-semimetal transition is observed. The type-II vdW heterostructure is still maintained during the changes of external electric field. Especially, when the electric field reaches to +0.7 V/Å, the impurity states have been eliminated with the band gap of 2.3 eV. An analysis of optical properties shows that the absorption coefficient in the visible-light region is enhanced considerably as the electric-field strength increases. Our calculation results suggest that the ultrathin hybrid layered g-C3N4/BiOCl nanocomposite may have significant advantages for visible-light photocatalysis.

  5. Dual-functional Pt-on-Pd supported on reduced graphene oxide hybrids: peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic.

    Science.gov (United States)

    Zhang, Xiahong; Wu, Genghuang; Cai, Zhixiong; Chen, Xi

    2015-03-01

    In this study, a facile hydrothermal method was developed to synthesize Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids. Because of the synergistic effect between Pt-on-Pd and RGO, the obtained Pt-on-Pd/RGO had superior peroxidase-mimic activities in H2O2 reduction and TMB oxidation. The reaction medium was optimized and a sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 μM of H2O2. In addition, the characteristic of electrocatalytic oxidation of methanol was investigated. The peak current density value, j(f), for the Pt-on-Pd/RGO hybrid (328 mA mg(Pt)(-1)) was about 1.85 fold higher than that of commercial Pt black (177 mA mg(Pt)(-1)) and, also, more durable electrocatalytic activity could be obtained. For the first time, the dual-functional Pt-on-Pd/RGO with peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic was reported. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Hybrid online sensor error detection and functional redundancy for systems with time-varying parameters.

    Science.gov (United States)

    Feng, Jianyuan; Turksoy, Kamuran; Samadi, Sediqeh; Hajizadeh, Iman; Littlejohn, Elizabeth; Cinar, Ali

    2017-12-01

    Supervision and control systems rely on signals from sensors to receive information to monitor the operation of a system and adjust manipulated variables to achieve the control objective. However, sensor performance is often limited by their working conditions and sensors may also be subjected to interference by other devices. Many different types of sensor errors such as outliers, missing values, drifts and corruption with noise may occur during process operation. A hybrid online sensor error detection and functional redundancy system is developed to detect errors in online signals, and replace erroneous or missing values detected with model-based estimates. The proposed hybrid system relies on two techniques, an outlier-robust Kalman filter (ORKF) and a locally-weighted partial least squares (LW-PLS) regression model, which leverage the advantages of automatic measurement error elimination with ORKF and data-driven prediction with LW-PLS. The system includes a nominal angle analysis (NAA) method to distinguish between signal faults and large changes in sensor values caused by real dynamic changes in process operation. The performance of the system is illustrated with clinical data continuous glucose monitoring (CGM) sensors from people with type 1 diabetes. More than 50,000 CGM sensor errors were added to original CGM signals from 25 clinical experiments, then the performance of error detection and functional redundancy algorithms were analyzed. The results indicate that the proposed system can successfully detect most of the erroneous signals and substitute them with reasonable estimated values computed by functional redundancy system.

  7. Corn stover fractions as a function of hybrid, maturity, site and year

    Energy Technology Data Exchange (ETDEWEB)

    Lizotte, P.L. [Laval Univ., Quebec City, PQ (Canada). Dept. des sols et de genie agroalimentaire; Savoie, P. [Agriculture and Agri-Food Canada, Quebec City, PQ (Canada); Lefsrud, M. [McGill Univ., Macdonald College, Ste-Anne-de-Bellevue, PQ (Canada). Dept. of Biosystems Engineering

    2010-07-01

    Corn stover is usually left on the ground following corn harvest so that it can be incorporated into the soil as organic matter and to protect against erosion. Part of the corn stover is oxidized in the atmosphere. Corn stover represents between 40 and 50 per cent of the dry matter (DM) contained in the aerial biomass of corn plants. Recent studies have shown that half of the corn stover could be harvested sustainably on low-sloping land under no-till practice. In Quebec, where 400,000 ha of corn are planted each year, corn stover could provide one million t DM of currently neglected biomass. Various hybrids of corn were monitored from early September to late November at 4 different sites during 2007, 2008 and 2009. Whole plants cut at 100 mm above the ground were collected weekly and separated into 7 fractions, notably the grain, the cob, the husk, the stalk below the ear, the stalk above the ear, the leaves below the ear and the leaves above the ear. In 2007, corn ears on average, were at 0.96 m above the ground at a site with low crop heat units (CHU). Hybrids grown in a warmer site were taller and their ears were 1.21 m above the ground. The DM partitioned in 7 components was 54 per cent grain, 14 per cent bottom stalk, 6 per cent top stalk, 5 per cent bottom leaves, 7 per cent top leaves, 5 per cent husk and 9 per cent cob. The total mass of fibre during harvest decreased from 8.9 to 6.6 t DM/ha for a low CHU hybrid and from 9.3 to 8.3 t DM/ha for a high CHU hybrid. Grain yield increased in 2008 from 3.8 to 7.6 t DM/ha over a 12-week period.

  8. Relative biocompatibility of micro-hybrid and nano-hybrid light-activated composite resins.

    Science.gov (United States)

    Olabisi Arigbede, Abiodun; Folasade Adeyemi, Bukola; Femi-Akinlosotu, Omowumi

    2017-01-01

    Background. In vitro studies have revealed a direct association between resin content and cytotoxicity of composite resins; however, implantation studies in this regard are sparse. This study investigates the relationship between filler content of composite resins and biocompatibility. Methods. This research employed twelve 180‒200-gr male Wistar rats, 1 nano-hybrid (Prime-Dent Inc.) and 1 micro-hybrid (Medental Inc.) composite resins containing 74% and 80‒90% filler content, respectively. The samples were assessed on the 2nd, 14th and 90th day of implantation. Four rats were allocated to each day in this experimental study. A section of 1.5mm long cured nano-hybrid and micro-hybrid materials were implanted into the right and left upper and lower limbs of the rats, respectively. Eight samples were generated on each day of observation. Inflammation was graded according to the criteria suggested by Orstavik and Major. Pearson's chi-squared test was employed to determine the relationship between the tissue responses of the two materials. Statistical significance was set at P resin had a score of 3.0 for cellular inflammation. On the 14th day, the micro-hybrid resin also exhibited a lower average grade for cellular inflammation. On the 90th day, the micro-hybrid resin had a higher grade of inflammation (0.9) compared to 0.3 recorded for nano-hybrid. The composite resins with higher filler content elicited a significantly lower grade of inflammation irrespective of the duration (χ=20.000, df=8, P=0.010) while the composite resins with lower filler content elicited a significantly lower inflammatory response on the 90th day (χ=4.000, df=1, P=0.046). Conclusion. The composite resins with higher filler content generally elicited significantly lower grades of inflammation, and the composite resins with lower filler content exhibited significantly lower inflammatory response on the 90th day of implantation.

  9. Local coordination of Eu(III) in organic/inorganic amine functionalized hybrids

    International Nuclear Information System (INIS)

    Carlos, L.D.; Sa Ferreira, R.A.; Goncalves, M.C.; Zea Bermudez, V. de

    2004-01-01

    The sol-gel method was used to prepare two families of organic/inorganic hybrids incorporating europium triflate, classed as di-urethanesils and aminosils. A siliceous network to which short polyether chains are covalently bonded through urethane linkages, composes the di-urethanesil host. A siliceous network containing pendant amine terminated propyl chains, forms the aminosils. The xerogels were investigated by photoluminescence, particularly the local interaction between the Eu 3+ ions and the host matrix. The Eu 3+ local coordination was modelled in terms of a local-field perturbation representing the ion's nearest ligands interaction potential. While for the aminosils the Eu 3+ ions occupy one low-symmetry local site--crystal-field strength of ca. 760.5 cm -1 and 5 D 0 lifetime of 0.6-0.7 ms--two local Eu 3+ environments with distinct point symmetry group, 5 D 0 lifetimes (ca. 0.2-0.3 and 1.4-1.8 ms, respectively) and covalent nature--crystal-field strengths of ca. 540 and 740-780 cm -1 , respectively--were identified in the di-urethanesils

  10. DFT studies for three Cu(II) coordination polymers: Geometrical and electronic structures, g factors and UV-visible spectra

    Science.gov (United States)

    Ding, Chang-Chun; Wu, Shao-Yi; Xu, Yong-Qiang; Wu, Li-Na; Zhang, Li-Juan

    2018-05-01

    This work presents a systematic density functional theory (DFT) study for geometrical and electronic structures, g factors and UV-vis spectra of three Cu(II) coordination polymers (CPs) [Cu(XL)(NO3)2]n (1), {[Cu(XL)(4,4‧-bpy)(NO3)2]•CH3CN}n (2) and {[Cu(XL)3](NO3)2·3.5H2O}n (3) based on the ligand N,N‧-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxdiimide bi(1,2,4-triazole) (XL) with the linker triazole coordinated with copper to construct the CPs. For three CPs with distinct ligands, the optimized molecular structures with PBE0 hybrid functional and the 6-311g basis set agree well with the corresponding XRD data. Meanwhile, the electronic properties are also analyzed for all the systems. The calculated g factors are found sensitive to the (Hartree-Fock) HF character due to the significant hybridization between copper and ligand orbitals. The calculated UV-visible spectra reveal that the main electronic transitions for CP 1 contain d-d and CT transitions, while those for CPs 2 and 3 largely belong to CT ones. The present CPs seem difficult to adsorb small molecules, e.g., CP 1 with H2O and NO2 exhibit unfavorable adsorption and deformation structures near the Cu2+ site.

  11. The structural, electronic, magnetic, and mechanical properties of perovskite oxides PbM1/2Nb1/2O3 (M = Fe, Co and Ni)

    Science.gov (United States)

    Erkisi, A.; Surucu, G.; Deligoz, E.

    2018-03-01

    In this study, the structural, electronic, magnetic, and mechanical properties of perovskite oxides PbM1/2Nb1/2O3 (M = Fe, Co and Ni) are investigated. The systems are treated in ferromagnetic order. The calculations are carried out in the framework of density functional theory (DFT) within the plane-wave pseudopotential method. The exchange-correlation potential is approximated by generalized-gradient spin approach (GGA). The intra-atomic Coulomb repulsion is also taken into account in calculations (GGA + U). We have considered two generalized-gradient spin approximation functionals, which are Perdew-Burke-Ernzerhof (PBE) and PBE for solids (PBEsol) for structural parameter calculations when it included Hubbard potential. Although the spin-polarized electronic band structures of PbCo1/2Nb1/2O3 and PbNi1/2Nb1/2O3 systems exhibit metallic property in ferromagnetic phase, a bandgap is observed in spin-down states of PbFe1/2Nb1/2O3 resulting in half-metallic behavior. The main reason for this behavior is attributed to the hybridization between d-states of transition metal atoms and p-states of oxygen atoms. The stability mechanically and the calculated mechanical properties by using elastic constants show that these compounds are mechanically stable in tetragonal phase and have anisotropic character mechanically.

  12. Covalent immobilization of lipase onto chitosan-mesoporous silica hybrid nanomaterials by carboxyl functionalized ionic liquids as the coupling agent.

    Science.gov (United States)

    Xiang, Xinran; Suo, Hongbo; Xu, Chao; Hu, Yi

    2018-05-01

    Chitosan-mesoporous silica SBA-15 hybrid nanomaterials (CTS-SBA-15) were synthesized by means of carboxyl functionalized ionic liquids as the coupling agent. The as-prepared CTS-SBA-15 support was characterized by TEM, FTIR, TG and nitrogen adsorption-desorption techniques. Porcine pancreas lipase (PPL) was then bound to the hybrid nanomaterials by using the cross-linking reagent glutaraldehyde (GA). Further, the parameters like cross-linking concentration, time and ratio of supports to enzyme were optimized. The property of immobilized lipase were tested in detail by enzyme activity assays. The results indicated that the hybrid nanomaterials could form three-dimensional (3D) structure with homogeneous mesoporous structures and immobilized PPL revealed excellent enzymatic performance. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Influence of in vitro gastrointestinal digestion of fruit juices enriched with pine bark extract on intestinal microflora.

    Science.gov (United States)

    López-Nicolás, Rubén; González-Bermúdez, Carlos A; Ros-Berruezo, Gaspar; Frontela-Saseta, Carmen

    2014-08-15

    The selective antimicrobial effect of fruit juices enriched with pine bark extract (PBE) (0.5 g/L) has been studied before and after in vitro gastrointestinal digestion. PBE (a concentrate of water-soluble bioflavonoids, mainly including phenolic compounds) has been proven to have high stability to the digestion process. Pure phenolic compounds such as gallic acid had a high antimicrobial effect on Staphylococcus aureus and Escherichia coli, maintaining the lactic acid bacteria population (≈100%). Otherwise, E. coli O157:H7 only growth 50% when PBE was added to the culture media, while a slight increase on the growth of lactobacilli and bifidobacteria was observed after exposition to the bark extract. Fresh fruit juices enriched with PBE showed the highest inhibitory effect on pathogenic intestinal bacterial growth, mainly E. coli and Enterococcus faecalis. The in vitro digestion process reduced the antibacterial effect of juices against most pathogenic bacteria in approximately 10%. However, the beneficial effect of fruit juices enriched with PBE (0.5 g/L) on gut microbiota is still considerable after digestion. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Nanostructured diamine-fullerene derivatives: computational density functional theory study and experimental evidence for their formation via gas-phase functionalization.

    Science.gov (United States)

    Contreras-Torres, Flavio F; Basiuk, Elena V; Basiuk, Vladimir A; Meza-Laguna, Víctor; Gromovoy, Taras Yu

    2012-02-16

    Nanostructure derivatives of fullerene C(60) are used in emerging applications of composite matrices, including protective and decorative coating, superadsorbent material, thin films, and lightweight high-strength fiber-reinforced materials, etc. In this study, quantum chemical calculations and experimental studies were performed to analyze the derivatives of diamine-fullerene prepared by the gas-phase solvent-free functionalization technique. In particular, the aliphatic 1,8-diamino-octane and the aromatic 1,5-diaminonaphthalene, which are diamines volatile in vacuum, were studied. We addressed two alternative mechanisms of the amination reaction via polyaddition and cross-linking of C(60) with diamines, using the pure GGA BLYP, PW91, and PBE functionals; further validation calculations were performed using the semiempirical dispersion GGA B97-D functional which contains parameters that have been specially adjusted by a more realistic view on dispersion contributions. In addition, we looked for experimental evidence for the covalent functionalization by using laser desorption/ionization time-of-flight mass spectrometry, thermogravimetric analysis, and atomic force microscopy.

  15. A PDMS/paper/glass hybrid microfluidic biochip integrated with aptamer-functionalized graphene oxide nano-biosensors for one-step multiplexed pathogen detection

    OpenAIRE

    Zuo, Peng; Li, XiuJun; Dominguez, Delfina C.; Ye, Bang-Ce

    2013-01-01

    Infectious pathogens often cause serious public health concerns throughout the world. There is an increasing demand for simple, rapid and sensitive approaches for multiplexed pathogen detection. In this paper we have developed a polydimethylsiloxane (PDMS)/paper/glass hybrid microfluidic system integrated with aptamer-functionalized graphene oxide (GO) nano-biosensors for simple, one-step, multiplexed pathogen detection. The paper substrate used in this hybrid microfluidic system facilitated ...

  16. Hybrid calcium phosphate coatings for implants

    Science.gov (United States)

    Malchikhina, Alena I.; Shesterikov, Evgeny V.; Bolbasov, Evgeny N.; Ignatov, Viktor P.; Tverdokhlebov, Sergei I.

    2016-08-01

    Monophasic biomaterials cannot provide all the necessary functions of bones or other calcined tissues. It is necessary to create for cancer patients the multiphase materials with the structure and composition simulating the natural bone. Such materials are classified as hybrid, obtained by a combination of chemically different components. The paper presents the physical, chemical and biological studies of coatings produced by hybrid technologies (HT), which combine primer layer and calcium phosphate (CaP) coating. The first HT type combines the method of vacuum arc titanium primer layer deposition on a stainless steel substrate with the following micro-arc oxidation (MAO) in phosphoric acid solution with addition of calcium compounds to achieve high supersaturated state. MAO CaP coatings feature high porosity (2-8%, pore size 5-7 µm) and surface morphology with the thickness greater than 5 µm. The thickness of Ti primer layer is 5-40 µm. Amorphous MAO CaP coating micro-hardness was measured at maximum normal load Fmax = 300 mN. It was 3.1 ± 0.8 GPa, surface layer elasticity modulus E = 110 ± 20 GPa, roughness Ra = 0.9 ± 0.1 µm, Rz = 7.5 ± 0.2 µm, which is less than the titanium primer layer roughness. Hybrid MAO CaP coating is biocompatible, able to form calcium phosphates from supersaturated body fluid (SBF) solution and also stimulates osteoinduction processes. The second HT type includes the oxide layer formation by thermal oxidation and then CaP target radio frequency magnetron sputtering (RFMS). Oxide-RFMS CaP coating is a thin dense coating with good adhesion to the substrate material, which can be used for metal implants. The RFMS CaP coating has thickness 1.6 ± 0.1 µm and consists of main target elements calcium and phosphorus and Ca/P ratio 2.4. The second HT type can form calcium phosphates from SBF solution. In vivo study shows that hybrid RFMS CaP coating is biocompatible and produces fibrointegration processes.

  17. Programmable release of multiple protein drugs from aptamer-functionalized hydrogels via nucleic acid hybridization.

    Science.gov (United States)

    Battig, Mark R; Soontornworajit, Boonchoy; Wang, Yong

    2012-08-01

    Polymeric delivery systems have been extensively studied to achieve localized and controlled release of protein drugs. However, it is still challenging to control the release of multiple protein drugs in distinct stages according to the progress of disease or treatment. This study successfully demonstrates that multiple protein drugs can be released from aptamer-functionalized hydrogels with adjustable release rates at predetermined time points using complementary sequences (CSs) as biomolecular triggers. Because both aptamer-protein interactions and aptamer-CS hybridization are sequence-specific, aptamer-functionalized hydrogels constitute a promising polymeric delivery system for the programmable release of multiple protein drugs to treat complex human diseases.

  18. Survival of the most transferable at the top of Jacob's ladder: Defining and testing the ωB97M(2) double hybrid density functional

    Science.gov (United States)

    Mardirossian, Narbe; Head-Gordon, Martin

    2018-06-01

    A meta-generalized gradient approximation, range-separated double hybrid (DH) density functional with VV10 non-local correlation is presented. The final 14-parameter functional form is determined by screening trillions of candidate fits through a combination of best subset selection, forward stepwise selection, and random sample consensus (RANSAC) outlier detection. The MGCDB84 database of 4986 data points is employed in this work, containing a training set of 870 data points, a validation set of 2964 data points, and a test set of 1152 data points. Following an xDH approach, orbitals from the ωB97M-V density functional are used to compute the second-order perturbation theory correction. The resulting functional, ωB97M(2), is benchmarked against a variety of leading double hybrid density functionals, including B2PLYP-D3(BJ), B2GPPLYP-D3(BJ), ωB97X-2(TQZ), XYG3, PTPSS-D3(0), XYGJ-OS, DSD-PBEP86-D3(BJ), and DSD-PBEPBE-D3(BJ). Encouragingly, the overall performance of ωB97M(2) on nearly 5000 data points clearly surpasses that of all of the tested density functionals. As a Rung 5 density functional, ωB97M(2) completes our family of combinatorially optimized functionals, complementing B97M-V on Rung 3, and ωB97X-V and ωB97M-V on Rung 4. The results suggest that ωB97M(2) has the potential to serve as a powerful predictive tool for accurate and efficient electronic structure calculations of main-group chemistry.

  19. Activation analysis and waste management for blanket materials of multi-functional experimental fusion–fission hybrid reactor (FDS-MFX)

    International Nuclear Information System (INIS)

    Jiang, Jieqiong; Yuan, Baoxin; Zou, Jun; Wu, Yican

    2014-01-01

    The preliminary studies of the activation analysis and waste management for blanket materials of the multi-functional experimental fusion–fission hybrid reactor, i.e. Multi-Functional eXperimental Fusion Driven Subcritical system named FDS-MFX, were performed. The neutron flux of the FDS-MFX blanket was calculated using VisualBUS code and Hybrid Evaluated Nuclear Data Library (HENDL) developed by FDS Team. Based on these calculated neutron fluxes, the activation properties of blanket materials were analyzed by the induced radioactivity, the decay heat and the contact dose rate for different regions of the FDS-MFX blanket. The safety and environment assessment of fusion power (SEAFP) strategy, which was developed in Europe, was applied to FDS-MFX blanket for the management of activated materials. Accordingly, the classification and management strategy of activated materials after different cooling time were proposed for FDS-MFX blanket

  20. Geometrical correction for the inter- and intramolecular basis set superposition error in periodic density functional theory calculations.

    Science.gov (United States)

    Brandenburg, Jan Gerit; Alessio, Maristella; Civalleri, Bartolomeo; Peintinger, Michael F; Bredow, Thomas; Grimme, Stefan

    2013-09-26

    We extend the previously developed geometrical correction for the inter- and intramolecular basis set superposition error (gCP) to periodic density functional theory (DFT) calculations. We report gCP results compared to those from the standard Boys-Bernardi counterpoise correction scheme and large basis set calculations. The applicability of the method to molecular crystals as the main target is tested for the benchmark set X23. It consists of 23 noncovalently bound crystals as introduced by Johnson et al. (J. Chem. Phys. 2012, 137, 054103) and refined by Tkatchenko et al. (J. Chem. Phys. 2013, 139, 024705). In order to accurately describe long-range electron correlation effects, we use the standard atom-pairwise dispersion correction scheme DFT-D3. We show that a combination of DFT energies with small atom-centered basis sets, the D3 dispersion correction, and the gCP correction can accurately describe van der Waals and hydrogen-bonded crystals. Mean absolute deviations of the X23 sublimation energies can be reduced by more than 70% and 80% for the standard functionals PBE and B3LYP, respectively, to small residual mean absolute deviations of about 2 kcal/mol (corresponding to 13% of the average sublimation energy). As a further test, we compute the interlayer interaction of graphite for varying distances and obtain a good equilibrium distance and interaction energy of 6.75 Å and -43.0 meV/atom at the PBE-D3-gCP/SVP level. We fit the gCP scheme for a recently developed pob-TZVP solid-state basis set and obtain reasonable results for the X23 benchmark set and the potential energy curve for water adsorption on a nickel (110) surface.

  1. Pseudocapacitive organic catechol derivative-functionalized three-dimensional graphene aerogel hybrid electrodes for high-performance supercapacitors

    Science.gov (United States)

    Choi, Jaewon; Yang, MinHo; Kim, Sung-Kon

    2017-11-01

    Bio-inspired and environmentally friendly chemical functionalization is a successful way to a new class of hybrid electrode materials for applications in energy storage. Quinone (Q)-hydroquinone (QH2) couples, a prototypical example of organic redox systems, provide fast and reversible proton-coupled electron-transfer reactions which lead to increased capacity. To achieve high capacitance and rate performance, constructing three-dimensional (3D) continuous porous structure is highly desirable. Here we report the hybrid electrodes (GA-C) consisting of 3D graphene aerogel (GA) functionalized with organic redox-active material, catechol derivative, for application to high-performance supercapacitors. The catechol derivative is adsorbed on the surface of GA through non-covalent interactions and promotes fast and reversible Q/QH2 faradaic reactions, providing large specific capacitance of 188 F g-1 at a current of 1 A g-1 and a specific energy of ∼25 Wh kg-1 at a specific power of ∼18,000 W kg-1. 3D continuous porous structure of GA electrode facilitates ion and electron transports, resulting in high rate performance (∼140 F g-1 at a current of 10 A g-1).

  2. Structural properties of small Lin (n = 5-8) atomic clusters via ab initio random structure searching: A look into the role of different implementations of long-range dispersion corrections

    Science.gov (United States)

    Putungan, Darwin Barayang; Lin, Shi-Hsin

    2018-01-01

    In this work, we looked into the lowest energy structures of small lithium clusters (Lin, n = 5, 6, 7, 8) utilizing conventional PBE exchange-correlation functional, PBE with D2 dispersion correction and PBE with Tkatchenko and Scheffler (TS) dispersion correction, and searched using ab initio random structure searching. Results show that in general, dispersion-corrected PBE obtained similar lowest minima structures as those obtained via conventional PBE regardless of the type of implementation, although both D2 and TS found several high-energy isomers that conventional PBE did not arrive at, with TS in general giving more structures per energy range that could be attributed to its environment-dependent implementation. Moreover, D2 and TS dispersion corrections found a lowest energy geometry for Li8 cluster that is in agreement with the structure obtained via the typical benchmarking method diffusion Monte Carlo in a recent work. It is thus suggested that for much larger lithium clusters, utilization of dispersion correction could be of help in searching for lowest energy minima that is in close agreement with that of diffusion Monte Carlo results, but computationally inexpensive.

  3. Comparison of HfCl4, HfI4, TEMA-Hf, and TDMA-Hf as precursors in early growing stages of HfO2 films deposited by ALD: A DFT study

    Science.gov (United States)

    Cortez-Valadez, M.; Fierro, C.; Farias-Mancilla, J. R.; Vargas-Ortiz, A.; Flores-Acosta, M.; Ramírez-Bon, R.; Enriquez-Carrejo, J. L.; Soubervielle-Montalvo, C.; Mani-Gonzalez, P. G.

    2016-06-01

    The final structure of HfO2 films grown by atomic layer deposition (ALD) after reaction with OH- ions has been analyzed by DFT (density functional theory). The interaction of the precursors: HfCl4 (hafnium tetrachloride), HfI4 (hafnium tetraiodide), TEMA-Hf (tetrakis-ethylmethylamino hafnium), and TDMA-Hf (tetrakis-dimethylamino hafnium) with HO-H was studied employing the B3LYP (Becke 3-parameter, Lee-Yang-Parr) hybrid functional and the PBE (Perdew-Burke-Ernzerhof) generalized gradient functional. The structural evolution at the Si(100) surface has been analyzed by LDA (local density approximation). The structural parameters: bond length and bond angle, and the vibrational parameters for the optimized structures are also reported. The presence of hafnium silicate at the interface was detected. The infrared spectra and structural parameters obtained in this work agree with previously reported experimental results.

  4. Polyglycerol-functionalized nanodiamond as a platform for gene delivery: Derivatization, characterization, and hybridization with DNA

    Directory of Open Access Journals (Sweden)

    Li Zhao

    2014-03-01

    Full Text Available A gene vector consisting of nanodiamond, polyglycerol, and basic polypeptide (ND-PG-BPP has been designed, synthesized, and characterized. The ND-PG-BPP was synthesized by PG functionalization of ND through ring-opening polymerization of glycidol on the ND surface, multistep organic transformations (–OH → –OTs (tosylate → –N3 in the PG layer, and click conjugation of the basic polypeptides (Arg8, Lys8 or His8 terminated with propargyl glycine. The ND-PG-BPP exhibited good dispersibility in water (>1.0 mg/mL and positive zeta potential ranging from +14.2 mV to +44.1 mV at neutral pH in Milli-Q water. It was confirmed by gel retardation assay that ND-PG-Arg8 and ND-PG-Lys8 with higher zeta potential hybridized with plasmid DNA (pDNA through electrostatic attraction, making them promising as nonviral vectors for gene delivery.

  5. Polyglycerol-functionalized nanodiamond as a platform for gene delivery: Derivatization, characterization, and hybridization with DNA

    Science.gov (United States)

    Zhao, Li; Nakae, Yuki; Qin, Hongmei; Ito, Tadamasa; Kimura, Takahide; Kojima, Hideto; Chan, Lawrence

    2014-01-01

    Summary A gene vector consisting of nanodiamond, polyglycerol, and basic polypeptide (ND-PG-BPP) has been designed, synthesized, and characterized. The ND-PG-BPP was synthesized by PG functionalization of ND through ring-opening polymerization of glycidol on the ND surface, multistep organic transformations (–OH → –OTs (tosylate) → –N3) in the PG layer, and click conjugation of the basic polypeptides (Arg8, Lys8 or His8) terminated with propargyl glycine. The ND-PG-BPP exhibited good dispersibility in water (>1.0 mg/mL) and positive zeta potential ranging from +14.2 mV to +44.1 mV at neutral pH in Milli-Q water. It was confirmed by gel retardation assay that ND-PG-Arg8 and ND-PG-Lys8 with higher zeta potential hybridized with plasmid DNA (pDNA) through electrostatic attraction, making them promising as nonviral vectors for gene delivery. PMID:24778723

  6. Photocatalytic oxidation removal of Hg{sup 0} using ternary Ag/AgI-Ag{sub 2}CO{sub 3} hybrids in wet scrubbing process under fluorescent light

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Anchao, E-mail: aczhang@qq.com [School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao [School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, 454000 (China); Xiang, Jun, E-mail: xiangjun@mail.hust.edu.cn [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan, 430074 (China)

    2017-01-15

    Highlights: • Ag/AgI-Ag{sub 2}CO{sub 3} hybrids were employed for Hg{sup 0} removal under fluorescent light. • Superoxide radical (·O{sub 2}{sup −}) played a key role in Hg{sup 0} removal. • NO exhibited a significant effect on Hg{sup 0} removal in comparison to SO{sub 2}. • The mechanism for enhanced Hg{sup 0} removal over Ag/AgI-Ag{sub 2}CO{sub 3} was proposed. - Abstract: A series of ternary Ag/AgI-Ag{sub 2}CO{sub 3} photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg{sup 0} removal in a wet scrubbing reactor. The hybrids were characterized by N{sub 2} adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg{sup 0} removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg{sup 0} removal. NO exhibited significant effect on Hg{sup 0} removal in comparison to SO{sub 2}. Among these ternary Ag/AgI-Ag{sub 2}CO{sub 3} hybrids, Ag/AgI(0.1)-Ag{sub 2}CO{sub 3} showed the highest Hg{sup 0} removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag{sub 2}CO{sub 3} and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag{sup 0} NPs). The trapping studies of reactive radicals showed that the superoxide radicals (·O{sub 2}{sup −}) may play a key role in Hg{sup 0} removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg{sup 0} removal over Ag/AgI(0.1)-Ag{sub 2}CO{sub 3} hybrid under fluorescent light was proposed.

  7. Hybrid Density Functional Study of the Local Structures and Energy Levels of CaAl2O4:Ce3.

    Science.gov (United States)

    Lou, Bibo; Jing, Weiguo; Lou, Liren; Zhang, Yongfan; Yin, Min; Duan, Chang-Kui

    2018-05-03

    First-principles calculations were carried out for the electronic structures of Ce 3+ in calcium aluminate phosphors, CaAl 2 O 4 , and their effects on luminescence properties. Hybrid density functional approaches were used to overcome the well-known underestimation of band gaps of conventional density functional approaches and to calculate the energy levels of Ce 3+ ions more accurately. The obtained 4f-5d excitation and emission energies show good consistency with measured values. A detailed energy diagram of all three sites is obtained, which explains qualitatively all of the luminescent phenomena. With the results of energy levels calculated by combining the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE06) and the constraint occupancy approach, we are able to construct a configurational coordinate diagram to analyze the processes of capture of a hole or an electron and luminescence. This approach can be applied for systematic high-throughput calculations in predicting Ce 3+ activated luminescent materials with a moderate computing requirement.

  8. Computational phase diagrams of noble gas hydrates under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Teeratchanan, Pattanasak, E-mail: s1270872@sms.ed.ac.uk; Hermann, Andreas, E-mail: a.hermann@ed.ac.uk [Centre for Science at Extreme Conditions and SUPA, School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD (United Kingdom)

    2015-10-21

    We present results from a first-principles study on the stability of noble gas-water compounds in the pressure range 0-100 kbar. Filled-ice structures based on the host water networks ice-I{sub h}, ice-I{sub c}, ice-II, and C{sub 0} interacting with guest species He, Ne, and Ar are investigated, using density functional theory (DFT) with four different exchange-correlation functionals that include dispersion effects to various degrees: the non-local density-based optPBE-van der Waals (vdW) and rPW86-vdW2 functionals, the semi-empirical D2 atom pair correction, and the semi-local PBE functional. In the He-water system, the sequence of stable phases closely matches that seen in the hydrogen hydrates, a guest species of comparable size. In the Ne-water system, we predict a novel hydrate structure based on the C{sub 0} water network to be stable or at least competitive at relatively low pressure. In the Ar-water system, as expected, no filled-ice phases are stable; however, a partially occupied Ar-C{sub 0} hydrate structure is metastable with respect to the constituents. The ability of the different DFT functionals to describe the weak host-guest interactions is analysed and compared to coupled cluster results on gas phase systems.

  9. Experimental and DFT evaluation of the 1H and 13C NMR chemical shifts for calix[4]arenes

    Science.gov (United States)

    Guzzo, Rodrigo N.; Rezende, Michelle Jakeline Cunha; Kartnaller, Vinicius; Carneiro, José Walkimar de M.; Stoyanov, Stanislav R.; Costa, Leonardo Moreira da

    2018-04-01

    The density functional theory is employed to determine the efficiency of 11 exchange-correlation (XC) functionals to compute the 1H and 13C NMR chemical shifts of p-tert-butylcalix[4]arene (ptcx4, R1 = C(CH3)3) and congeners using the 6-31G(d,p) basis set. The statistical analysis shows that B3LYP, B3PW91 and PBE1PBE are the best XC functionals for the calculation of 1H chemical shifts. Moreover, the best results for the 13C chemical shifts are obtained using the LC-WPBE, M06-2X and wB97X-D functionals. The performance of these XC functionals is tested for three other calix[4]arenes: p-sulfonic acid calix[4]arene (sfxcx4 - R1 = SO3H), p-nitro-calix[4]arene (ncx4, R1 = NO2) and calix[4]arene (cx4 - R1 = H). For 1H chemical shifts B3LYP, B3PW91 and PBE1PBE yield similar results, although B3PW91 shows more consistency in the calculated error for the different structures. For 13C NMR chemical shifts, the XC functional that stood out as best is LC-WPBE. Indeed, the three functionals selected for each of 1H and 13C show good accuracy and can be used in future studies involving the prediction of 1H and 13C chemical shifts for this type of compounds.

  10. Expressed sequence tag analysis of functional genes associated with adventitious rooting in Liriodendron hybrids.

    Science.gov (United States)

    Zhong, Y D; Sun, X Y; Liu, E Y; Li, Y Q; Gao, Z; Yu, F X

    2016-06-24

    Liriodendron hybrids (Liriodendron chinense x L. tulipifera) are important landscaping and afforestation hardwood trees. To date, little genomic research on adventitious rooting has been reported in these hybrids, as well as in the genus Liriodendron. In the present study, we used adventitious roots to construct the first cDNA library for Liriodendron hybrids. A total of 5176 expressed sequence tags (ESTs) were generated and clustered into 2921 unigenes. Among these unigenes, 2547 had significant homology to the non-redundant protein database representing a wide variety of putative functions. Homologs of these genes regulated many aspects of adventitious rooting, including those for auxin signal transduction and root hair development. Results of quantitative real-time polymerase chain reaction showed that AUX1, IRE, and FB1 were highly expressed in adventitious roots and the expression of AUX1, ARF1, NAC1, RHD1, and IRE increased during the development of adventitious roots. Additionally, 181 simple sequence repeats were identified from 166 ESTs and more than 91.16% of these were dinucleotide and trinucleotide repeats. To the best of our knowledge, the present study reports the identification of the genes associated with adventitious rooting in the genus Liriodendron for the first time and provides a valuable resource for future genomic studies. Expression analysis of selected genes could allow us to identify regulatory genes that may be essential for adventitious rooting.

  11. Synthesis of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples.

    Science.gov (United States)

    Chen, Kun; Jin, Rongrong; Luo, Chen; Song, Guoxin; Hu, Yaoming; Cheng, Hefa

    2018-04-01

    A novel adsorbent made of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core-shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500 ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N = 3) were between 0.1 and 3.0 ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. G-centers in irradiated silicon revisited: A screened hybrid density functional theory approach

    KAUST Repository

    Wang, H.

    2014-05-13

    Electronic structure calculations employing screened hybrid density functional theory are used to gain fundamental insight into the interaction of carbon interstitial (Ci) and substitutional (Cs) atoms forming the CiCs defect known as G-center in silicon (Si). The G-center is one of the most important radiation related defects in Czochralski grown Si. We systematically investigate the density of states and formation energy for different types of CiCs defects with respect to the Fermi energy for all possible charge states. Prevalence of the neutral state for the C-type defect is established.

  13. SpaceCube v2.0 Space Flight Hybrid Reconfigurable Data Processing System

    Science.gov (United States)

    Petrick, Dave

    2014-01-01

    This paper details the design architecture, design methodology, and the advantages of the SpaceCube v2.0 high performance data processing system for space applications. The purpose in building the SpaceCube v2.0 system is to create a superior high performance, reconfigurable, hybrid data processing system that can be used in a multitude of applications including those that require a radiation hardened and reliable solution. The SpaceCube v2.0 system leverages seven years of board design, avionics systems design, and space flight application experiences. This paper shows how SpaceCube v2.0 solves the increasing computing demands of space data processing applications that cannot be attained with a standalone processor approach.The main objective during the design stage is to find a good system balance between power, size, reliability, cost, and data processing capability. These design variables directly impact each other, and it is important to understand how to achieve a suitable balance. This paper will detail how these critical design factors were managed including the construction of an Engineering Model for an experiment on the International Space Station to test out design concepts. We will describe the designs for the processor card, power card, backplane, and a mission unique interface card. The mechanical design for the box will also be detailed since it is critical in meeting the stringent thermal and structural requirements imposed by the processing system. In addition, the mechanical design uses advanced thermal conduction techniques to solve the internal thermal challenges.The SpaceCube v2.0 processing system is based on an extended version of the 3U cPCI standard form factor where each card is 190mm x 100mm in size The typical power draw of the processor card is 8 to 10W and scales with application complexity. The SpaceCube v2.0 data processing card features two Xilinx Virtex-5 QV Field Programmable Gate Arrays (FPGA), eight memory modules, a monitor

  14. Behavioural and spermatogenic hybrid male breakdown in Nasonia

    Science.gov (United States)

    Clark, Michael E.; O’Hara, F. Patrick; Chawla, Ankur; Werren, John H.

    2010-01-01

    Several reproductive barriers exists within the Nasonia species complex, including allopatry, premating behavioural isolation, postzygotic inviability and Wolbachia-induced cytoplasmic incompatibility. Here we show that hybrid males suffer two additional reproductive disadvantages, an inability to properly court females and decreased sperm production. Hybrid behavioural sterility, characterized by a reduced ability of hybrids to perform necessary courtship behaviours, occurs in hybrids between two species of Nasonia. Hybrid males produced in crosses between N. vitripennis and N. giraulti courted females at a reduced frequency (23-69%), compared to wild-type N. vitripennis and N. giraulti males (>93%). Reduced courtship frequency was not a simple function of inactivity among hybrids. A strong effect of cytoplasmic (mitochondrial) background was also found in N. vitripennis and N. giraulti crosses; F2 hybrids with giraulti cytoplasm showing reduced ability at most stages of courtship. Hybrids produced between a younger species pair, N. giraulti and N. longicornis, were behaviourally fertile. All males possessed motile sperm, but sperm production is greatly reduced in hybrids between the older species pair, N. vitripennis and N. giraulti. This effect on hybrid males, lowered sperm counts rather than non-functional sperm, is different from most described cases of hybrid male sterility and may represent an earlier stage of hybrid sperm breakdown. The results add to previous studies of F2 hybrid inviability and behavioural sterility, and indicated that Wolbachia induced hybrid incompatibility has arisen early in species divergence, relative to behavioural sterility and spermatogenic infertility. PMID:20087395

  15. Charge spill-out and work function of few-layer graphene on SiC(000 1)

    International Nuclear Information System (INIS)

    Renault, O; Rotella, H; Kaja, K; Blaise, P; Poiroux, T; Pascon, A M; Fonseca, L R C; Mathieu, C; Rault, J E; Barrett, N

    2014-01-01

    We report on the charge spill-out and work function of epitaxial few-layer graphene on 6 H-SiC(000 1). Experiments from high-resolution, energy-filtered x-ray photoelectron emission microscopy (XPEEM) are combined with ab initio density functional theory calculations using a relaxed interface model. The work function values obtained from theory and experiments are in qualitative agreement, reproducing the previously observed trend of increasing work function with each additional graphene plane. Electron transfer at the SiC/graphene interface through a buffer layer (BL) causes an interface dipole moment which is at the origin of the graphene work function modulation. The total charge transfer is independent of the number of graphene layers, and is consistent with the constant binding energy of the SiC component of the C 1s core-level, measured by XPEEM. Charge leakage into a vacuum depends on the number of graphene layers, explaining why the experimental, layer-dependent C 1s graphene core-level binding energy shift does not rigidly follow that of the work function. Thus, a combination of charge transfer at the SiC/graphene interface and charge spill-out into the vacuum resolves the apparent discrepancy between the experimental work function and C 1s binding energy. (paper)

  16. Surface modification of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} aiming to obtaining ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} hybrid for use as a biosensor; Modificacao da superficie do ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} visando a obtencao do hibrido ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} para aplicacao como biossensor

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, P.M.A.G.; Santos, P.T.A.; Costa, A.C.F.M., E-mail: pascally.guerra@gmail.com, E-mail: polyanaquimica@yahoo.com.br, E-mail: ana.costa@ufcg.edu.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Junior, S.A.; Viana, R. S., E-mail: salvesjr@ufpe.br, E-mail: rodrigosilva.viana@yahoo.com.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

    2017-01-15

    This study aimed to investigate the influence of surface modification of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} nanoparticles for obtaining hybrid ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} for application as a biosensor. Initially ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4} nanoparticles were synthesized by combustion reaction and, subsequently, their surfaces were modified with silane agent. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and excitation and emission spectroscopy. The results showed formation of ZnAl{sub 2}O{sub 4} as the major phase. By SEM, hard agglomerates, irregularly shaped in the form of plaques, with the presence of few irregular and variables pores were observed. The surface modification was confirmed by FTIR through the silanol and siloxane groups. The excitation and emission spectra revealed the presence of a broadband of ZnAl{sub 2} O{sub 4} matrix, and fine and intense transitions from europium ion arising from doping of non-stoichiometric ZnAl{sub 2}O{sub 4} with the europium. From the results of emission and excitation, it was observed that the luminescence of ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} hybrid presented a small decrease in relation to the ZnAl{sub 1.9}Eu0.0{sub 5}O{sub 4} nanoparticles. This decrease was almost insignificant in relation to the benefits of silanization caused by the introduction of functional groups that promote combination of hybrid ZnAl{sub 1.9}Eu{sub 0.05}O{sub 4}/SiO{sub 2} with biomolecules, being this promising for application as a biosensor used in the biomedical field for the diagnosis and treatment of diseases. (author)

  17. Constraints on parton density functions from D0

    Energy Technology Data Exchange (ETDEWEB)

    Hays, Jonathan M.; /Imperial Coll., London

    2008-04-01

    Five recent results from D0 which either impact or have the potential to impact on uncertainties in parton density functions are presented. Many analyses at D0 are sensitive to the modeling of the partonic structure of the proton. When theoretical and experimental uncertainties are well controlled there exists the possibility for additional constraints on parton density functions (PDF). Five measurements are presented which either have already been included in global parton fits or have the potential to contribute in the future.

  18. A Reinvestigation of the Dimer of para-Benzoquinone with Pyrimidine with MP2, CCSD(T) and DFT using Functionals including those Designed to Describe Dispersion

    Science.gov (United States)

    Marianski, Mateusz; Oliva, Antoni

    2012-01-01

    We reevaluate the interaction of pyridine and p-benzoquinone using functionals designed to treat dispersion. We compare the relative energies of four different structures: stacked, T-shaped (identified for the first time) and two planar H-bonded geometries using these functionals (B97-D, ωB97x-D, M05, M05-2X, M06, M06L, M06-2X), other functionals (PBE1PBE, B3LYP, X3LYP), MP2 and CCSD(T) using basis sets as large as cc-pVTZ. The functionals designed to treat dispersion behave erratically as the predictions of the most stable structure vary considerably. MP2 predicts the experimentally observed structure (H-bonded) to be the least stable, while single point CCSD(T) at the MP2 optimized geometry correctly predicts the observed structure to be most stable. We have confirmed the assignment of the experimental structure using new calculations of the vibrational frequency shifts previously used to identify the structure. The MP2/cc-pVTZ vibrational calculations are in excellent agreement with the observations. All methods used to calculate the energies provide vibrational shifts that agree with the observed structure even though most do not predict this structure to be most stable. The implications for evaluating possible π-stacking in biologically important systems are discussed. PMID:22765283

  19. A reinvestigation of the dimer of para-benzoquinone and pyrimidine with MP2, CCSD(T), and DFT using functionals including those designed to describe dispersion.

    Science.gov (United States)

    Marianski, Mateusz; Oliva, Antoni; Dannenberg, J J

    2012-08-02

    We reevaluate the interaction of pyridine and p-benzoquinone using functionals designed to treat dispersion. We compare the relative energies of four different structures: stacked, T-shaped (identified for the first time), and two planar H-bonded geometries using these functionals (B97-D, ωB97x-D, M05, M05-2X, M06, M06L, and M06-2X), other functionals (PBE1PBE, B3LYP, X3LYP), MP2, and CCSD(T) using basis sets as large as cc-pVTZ. The functionals designed to treat dispersion behave erratically as the predictions of the most stable structure vary considerably. MP2 predicts the experimentally observed structure (H-bonded) to be the least stable, while single-point CCSD(T) at the MP2 optimized geometry correctly predicts the observed structure to be the most stable. We have confirmed the assignment of the experimental structure using new calculations of the vibrational frequency shifts previously used to identify the structure. The MP2/cc-pVTZ vibrational calculations are in excellent agreement with the observations. All methods used to calculate the energies provide vibrational shifts that agree with the observed structure even though most do not predict this structure to be most stable. The implications for evaluating possible π-stacking in biologically important systems are discussed.

  20. Analysis of nonlinear optical properties in donor–acceptor materials

    Energy Technology Data Exchange (ETDEWEB)

    Day, Paul N. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); General Dynamics Information Technology, Inc., Dayton, Ohio 45431 (United States); Pachter, Ruth [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); Nguyen, Kiet A. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433 (United States); UES, Inc., Dayton, Ohio 45432 (United States)

    2014-05-14

    Time-dependent density functional theory has been used to calculate nonlinear optical (NLO) properties, including the first and second hyperpolarizabilities as well as the two-photon absorption cross-section, for the donor-acceptor molecules p-nitroaniline and dimethylamino nitrostilbene, and for respective materials attached to a gold dimer. The CAMB3LYP, B3LYP, PBE0, and PBE exchange-correlation functionals all had fair but variable performance when compared to higher-level theory and to experiment. The CAMB3LYP functional had the best performance on these compounds of the functionals tested. However, our comprehensive analysis has shown that quantitative prediction of hyperpolarizabilities is still a challenge, hampered by inadequate functionals, basis sets, and solvation models, requiring further experimental characterization. Attachment of the Au{sub 2}S group to molecules already known for their relatively large NLO properties was found to further enhance the response. While our calculations show a modest enhancement for the first hyperpolarizability, the enhancement of the second hyperpolarizability is predicted to be more than an order of magnitude.

  1. Epitaxial growth of hybrid nanostructures

    Science.gov (United States)

    Tan, Chaoliang; Chen, Junze; Wu, Xue-Jun; Zhang, Hua

    2018-02-01

    Hybrid nanostructures are a class of materials that are typically composed of two or more different components, in which each component has at least one dimension on the nanoscale. The rational design and controlled synthesis of hybrid nanostructures are of great importance in enabling the fine tuning of their properties and functions. Epitaxial growth is a promising approach to the controlled synthesis of hybrid nanostructures with desired structures, crystal phases, exposed facets and/or interfaces. This Review provides a critical summary of the state of the art in the field of epitaxial growth of hybrid nanostructures. We discuss the historical development, architectures and compositions, epitaxy methods, characterization techniques and advantages of epitaxial hybrid nanostructures. Finally, we provide insight into future research directions in this area, which include the epitaxial growth of hybrid nanostructures from a wider range of materials, the study of the underlying mechanism and determining the role of epitaxial growth in influencing the properties and application performance of hybrid nanostructures.

  2. An open-source framework for analyzing N-electron dynamics. II. Hybrid density functional theory/configuration interaction methodology.

    Science.gov (United States)

    Hermann, Gunter; Pohl, Vincent; Tremblay, Jean Christophe

    2017-10-30

    In this contribution, we extend our framework for analyzing and visualizing correlated many-electron dynamics to non-variational, highly scalable electronic structure method. Specifically, an explicitly time-dependent electronic wave packet is written as a linear combination of N-electron wave functions at the configuration interaction singles (CIS) level, which are obtained from a reference time-dependent density functional theory (TDDFT) calculation. The procedure is implemented in the open-source Python program detCI@ORBKIT, which extends the capabilities of our recently published post-processing toolbox (Hermann et al., J. Comput. Chem. 2016, 37, 1511). From the output of standard quantum chemistry packages using atom-centered Gaussian-type basis functions, the framework exploits the multideterminental structure of the hybrid TDDFT/CIS wave packet to compute fundamental one-electron quantities such as difference electronic densities, transient electronic flux densities, and transition dipole moments. The hybrid scheme is benchmarked against wave function data for the laser-driven state selective excitation in LiH. It is shown that all features of the electron dynamics are in good quantitative agreement with the higher-level method provided a judicious choice of functional is made. Broadband excitation of a medium-sized organic chromophore further demonstrates the scalability of the method. In addition, the time-dependent flux densities unravel the mechanistic details of the simulated charge migration process at a glance. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Synthesis, characterization, and nonlinear optical properties of graphene oxide functionalized with tetra-amino porphyrin

    Science.gov (United States)

    Yamuna, R.; Ramakrishnan, S.; Dhara, Keerthy; Devi, R.; Kothurkar, Nikhil K.; Kirubha, E.; Palanisamy, P. K.

    2013-01-01

    The synthesis of a porphyrin-graphene oxide hybrid (GO-TAP) was carried out by covalently functionalizing graphene oxide (GO) with 5,10,15,20 mesotetra (4-aminophenyl) porphyrin (TAP) through an amide linkage. The GO-TAP hybrid has been characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV-visible spectroscopy. The peak intensity of the Soret band of the material was suppressed compared to neat TAP. This indicates a strong interaction between the electronic energy level of TAP and GO in the GO-TAP hybrid. The functionalization of GO with TAP significantly improved its solubility and dispersion stability in organic solvents. Scanning electron micrographs reveal that the hybrid was found to be similar to the unmodified GO but slightly more wrinkled. Transmission electron micrographs also demonstrate that GO sheet in the hybrid is more wrinkled with some dark spot due to functionalization. Atomic force microscopy results also reveal that the TAP functionalization increases the thickness of GO sheet to 2.0-3.0 nm from 1.2 to 1.8 nm. We observed improved nonlinear optical and optical limiting properties for the hybrid compared to both graphene oxide and porphyrin. GO-TAP shows fluorescence quenching compared with porphyrin, indicating excellent electron and/or energy transfer to GO from TAP. Thermogravimetric analysis confirms that the GO-TAP hybrid has outstanding thermal stability.

  4. Synthesis, characterization, and nonlinear optical properties of graphene oxide functionalized with tetra-amino porphyrin

    International Nuclear Information System (INIS)

    Yamuna, R.; Ramakrishnan, S.; Dhara, Keerthy; Devi, R.; Kothurkar, Nikhil K.; Kirubha, E.; Palanisamy, P. K.

    2013-01-01

    The synthesis of a porphyrin–graphene oxide hybrid (GO–TAP) was carried out by covalently functionalizing graphene oxide (GO) with 5,10,15,20 mesotetra (4-aminophenyl) porphyrin (TAP) through an amide linkage. The GO–TAP hybrid has been characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV–visible spectroscopy. The peak intensity of the Soret band of the material was suppressed compared to neat TAP. This indicates a strong interaction between the electronic energy level of TAP and GO in the GO–TAP hybrid. The functionalization of GO with TAP significantly improved its solubility and dispersion stability in organic solvents. Scanning electron micrographs reveal that the hybrid was found to be similar to the unmodified GO but slightly more wrinkled. Transmission electron micrographs also demonstrate that GO sheet in the hybrid is more wrinkled with some dark spot due to functionalization. Atomic force microscopy results also reveal that the TAP functionalization increases the thickness of GO sheet to 2.0–3.0 nm from 1.2 to 1.8 nm. We observed improved nonlinear optical and optical limiting properties for the hybrid compared to both graphene oxide and porphyrin. GO–TAP shows fluorescence quenching compared with porphyrin, indicating excellent electron and/or energy transfer to GO from TAP. Thermogravimetric analysis confirms that the GO–TAP hybrid has outstanding thermal stability.

  5. Towards the development of a novel bioinspired functional material: synthesis and characterization of hybrid TiO2/DHICA-melanin nanoparticles.

    Science.gov (United States)

    Pezzella, Alessandro; Capelli, Luigia; Costantini, Aniello; Luciani, Giuseppina; Tescione, Fabiana; Silvestri, Brigida; Vitiello, Giuseppe; Branda, Francesco

    2013-01-01

    A large number of recent literature data focus on modification/modulation of surface chemistry of inorganic materials in order to improve their functional properties. Melanins, a wide class of natural pigments, are recently emerging as a powerful organic component for developing bioinspired active material for a large number of applications from organoelectronics to bioactive compounds. Here we report the use of the approach referred as "chimie douce", involving in situ formation of the hybrids through reactions of precursors under mild conditions, to prepare novel hybrid functional architectures based on eumelanin like 5,6 dihydroxyindole-2-carboxylic acid (DHICA) polymer and TiO2. Two synthesis procedures were carried out to get DHICA-melanin coated TiO2 nanoparticles as well as mixed DHICA/TiO2 hybrid nanostructures. Such systems were characterized through EPR, FT-IR and fluorescence spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and TEM microscopy in order to assess the effect of synthesis path as well as of DHICA content on structural, morphological and optical properties of TiO2 nanostructures. In particular, EPR, FT-IR spectra and TGA analysis confirmed the presence of DHICA-melanin in these samples. TEM measurements indicated the formation of the nanoparticles having relatively narrow size distribution with average particle size of about 10nm. DHICA-melanin does act as a morphological agent affecting morphology of hybrid nanostructures. XRD analysis proved that TiO2 hybrid nanoparticles kept anatase structures for DHICA-melanin contents within the range of investigated compositions, i.e. up to 50% wt/wt. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Carboxylated nitrile butadiene rubber/hybrid filler composites

    Directory of Open Access Journals (Sweden)

    Ahmad Mousa

    2012-08-01

    Full Text Available The surface properties of the OSW and NLS are measured with the dynamic contact-angle technique. The x-ray photoelectron spectroscopy (XPS of the OSW reveals that the OSW possesses various reactive functional groups namely hydroxyl groups (OH. Hybrid filler from NLS and OSW were incorporated into carboxylated nitrile rubber (XNBR to produce XNBR hybrid composites. The reaction of OH groups from the OSW with COOH of the XNBR is checked by attenuated total reflectance spectra (ATR-IR of the composites. The degree of curing ΔM (maximum torque-minimum torque as a function of hybrid filler as derived from moving die rheometer (MDR is reported. The stress-strain behavior of the hybrid composites as well as the dynamic mechanical thermal analysis (DMTA is studied. Bonding quality and dispersion of the hybrid filler with and in XNBR are examined using scanning-transmission electron microscopy (STEM in SEM.

  7. Hybrid epoxy–silane coatings for improved corrosion protection of Mg alloy

    International Nuclear Information System (INIS)

    Brusciotti, Fabiola; Snihirova, Darya V.; Xue, Huibin; Montemor, M. Fatima; Lamaka, Svetlana V.; Ferreira, Mario G.S.

    2013-01-01

    Highlights: ► Hybrid epoxy–silane coatings for corrosion protection of Mg alloy AZ31. ► Electrochemical impedance spectroscopy to study the corrosion behavior. ► Very good corrosion protection after 1 month immersion in 0.05 M NaCl. ► Surface and chemical characterization to understand corrosion processes. ► Influence of organic structure in coatings corrosion performance. - Abstract: New hybrid epoxy–silane coatings, with added functionalities for improved performance and durability, were designed to increase the corrosion protection of magnesium alloys. The corrosion behavior of the coated AZ31 was studied through electrochemical impedance spectroscopy (EIS) in 0.05 M NaCl. The morphology and surface chemistry of the samples were also investigated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) before and after immersion in the electrolyte. The new hybrid silane coatings showed a high resistance to corrosion that persisted throughout one-month immersion in a pH-neutral NaCl solution.

  8. A hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks.

    Science.gov (United States)

    Choi, Yong-Kyu; Hosoya, Kenta; Lee, Chung Ghiu; Hanawa, Masanori; Park, Chang-Soo

    2011-03-28

    We propose and experimentally demonstrate a hybrid WDM/OCDMA ring with a dynamic add/drop function based on Fourier code for local area networks. Dynamic function is implemented by mechanically tuning the Fourier encoder/decoder for optical code division multiple access (OCDMA) encoding/decoding. Wavelength division multiplexing (WDM) is utilized for node assignment and 4-chip Fourier code recovers the matched signal from the codes. For an optical source well adapted to WDM channels and its short optical pulse generation, reflective semiconductor optical amplifiers (RSOAs) are used with a fiber Bragg grating (FBG) and gain-switched. To demonstrate we experimentally investigated a two-node hybrid WDM/OCDMA ring with a 4-chip Fourier encoder/decoder fabricated by cascading four FBGs with the bit error rate (BER) of <10(-9) for the node span of 10.64 km at 1.25 Gb/s.

  9. Hybrid Zeolitic Imidazolate Frameworks: Controlling Framework Porosity and Functionality by Mixed-Linker Synthesis

    KAUST Repository

    Thompson, Joshua A.

    2012-05-22

    Zeolitic imidazolate frameworks (ZIFs) are a subclass of nanoporous metal-organic frameworks (MOFs) that exhibit zeolite-like structural topologies and have interesting molecular recognition properties, such as molecular sieving and gate-opening effects associated with their pore apertures. The synthesis and characterization of hybrid ZIFs with mixed linkers in the framework are described in this work, producing materials with properties distinctly different from the parent frameworks (ZIF-8, ZIF-90, and ZIF-7). NMR spectroscopy is used to assess the relative amounts of the different linkers included in the frameworks, whereas nitrogen physisorption shows the evolution of the effective pore size distribution in materials resulting from the framework hybridization. X-ray diffraction shows these hybrid materials to be crystalline. In the case of ZIF-8-90 hybrids, the cubic space group of the parent frameworks is continuously maintained, whereas in the case of the ZIF-7-8 hybrids there is a transition from a cubic to a rhombohedral space group. Nitrogen physisorption data reveal that the hybrid materials exhibit substantial changes in gate-opening phenomena, either occurring at continuously tunable partial pressures of nitrogen (ZIF-8-90 hybrids) or loss of gate-opening effects to yield more rigid frameworks (ZIF-7-8 hybrids). With this synthetic approach, significant alterations in MOF properties may be realized to suit a desired separation or catalytic process. © 2012 American Chemical Society.

  10. Hybrid RPA-cluster model for the dipole strength function of sup(11)Li

    International Nuclear Information System (INIS)

    Teruya, N.; Bertulani, C.A.; Krewald, S.

    1990-09-01

    A hybrid RPA-cluster model is developed and applied to the calculation of the dipole response of sup(11)L1. A strong collective state at 1.81 MeV is found. Its width is predicted to be 4.0 MeV. The electromagnetic excitation cross section was found to be 700 mb for sup(11)L1 + sup(208)Pb (E = 800 MeV/n), close to the experimental result. (author)

  11. Evaluation of the effects of paederus beetle extract and gamma irradiation on HeLa cells

    Directory of Open Access Journals (Sweden)

    Fariba Samani

    2014-04-01

    Full Text Available Objective(s:Cervical cancer is a malignancy that is the second most common cause of death from cancer in women throughout the world. Paederus beetle (Paederus fuscipes extract (PBE, contains bioactive compounds such as pederine which has cytotoxic properties and blocks DNA and protein synthesis at very low concentrations. In this investigation we tried to determine the effects co-treatment with PBE and gamma irradiation on HeLa cells. Materials and Methods: The viability of the cells was measured by two methods: MTT and Colony assay. Results: We found that supplementing gamma irradiation therapy with PBE does not increase cell death and it might even interfere with its cytotoxicty at the concentrations below 0.1 ng/ml and the viability for irradiation vs irradiation + PBE was 37%: 60%.   Conclusion: This finding might be due to radioprotective effects of the very low doses of PBE against gamma radiation.

  12. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

    2017-02-28

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  13. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    International Nuclear Information System (INIS)

    Hu, Jie; Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong; Lian, Kun

    2017-01-01

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM"−"1 cm"−"2 and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM"−"1 cm"−"2 in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  14. Electrochemical performance of LiNi0.5Mn1.5O4 prepared by improved solid state method as cathode in hybrid supercapacitor

    International Nuclear Information System (INIS)

    Wu Huiming; Rao, Ch. Venkateswara; Rambabu, B.

    2009-01-01

    The electrochemical performance of a hybrid asymmetric supercapacitor with activated carbon (AC) as anode and a lithium-ion intercalated compound LiNi 0.5 Mn 1.5 O 4 as cathode was studied. By using metal acetate precursors as starting materials in solid state reaction method, pure LiNi 0.5 Mn 1.5 O 4 was formed at low temperature. The role of precursors on the formation of material at low temperature and short period of time is presented. XRD confirms the cubic spinel structure (space group, Fd3m) and SEM shows the particles of size around 1 μm. The effect of the modified solid state reaction route on the structural and electrochemical properties was investigated. The fabricated hybrid supercapacitor, AC/LiNi 0.5 Mn 1.5 O 4 in a non-aqueous electrolyte 1.0 M LiPF 6 /EC-DMC exhibits a sloping voltage profile from 1.0 to 3.0 V and delivers a specific energy of ca. 56 Wh kg -1 . Moreover, it exhibits excellent cycling performance with less than 5% capacity loss over 1000 cycles.

  15. Facile synthesis of gold nanoparticles on propylamine functionalized SBA-15 and effect of surface functionality of its enhanced bactericidal activity against gram positive bacteria

    International Nuclear Information System (INIS)

    Bhuyan, Diganta; Saikia, Mrinal; Saikia, Lakshi; Gogoi, Animesh; Saikia, Ratul

    2015-01-01

    The facile synthesis of an SBA-15-pr- + NH 3 .Au 0 nano-hybrid material by spontaneous autoreduction of aqueous chloroaurate anions on propylamine functionalized SBA-15 was successfully demonstrated. The as-synthesized SBA-15-pr- + NH 3 .Au 0 nano-hybrid material was well characterized using low and wide angle x-ray diffraction (XRD), N 2 adsorption–desorption isotherms, Fourier transform infrared (FTIR), transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX), x-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy and atomic absorption spectroscopy (AAS). The activity of the nano-hybrid material as a potent bactericidal agent was successfully tested against Gram positive/negative bacteria viz. Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The colony killing percentage of Gram positive bacteria was found to be higher than Gram negative bacteria due to the stronger electrostatic interaction between the positively-charged amine functionality of SBA-15 and the negatively charged functionality of the bacterial cell wall. (paper)

  16. Flexible Pb(Zr0.52Ti0.48)O3 Films for a Hybrid Piezoelectric-Pyroelectric Nanogenerator under Harsh Environments.

    Science.gov (United States)

    Ko, Young Joon; Kim, Dong Yeong; Won, Sung Sik; Ahn, Chang Won; Kim, Ill Won; Kingon, Angus I; Kim, Seung-Hyun; Ko, Jae-Hyeon; Jung, Jong Hoon

    2016-03-01

    In spite of extremely high piezoelectric and pyroelectric coefficients, there are few reports on flexible ferroelectric perovskite film based nanogenerators (NGs). Here, we report the successful growth of a flexible Pb(Zr0.52Ti0.48)O3 (PZT) film and its application to hybrid piezoelectric-pyroelectric NG. A highly flexible Ni-Cr metal foil substrate with a conductive LaNiO3 bottom electrode enables the growth of flexible PZT film having high piezoelectric (140 pC/N) and pyroelectric (50 nC/cm(2)K) coefficients at room temperature. The flexible PZT-based NG effectively scavenges mechanical vibration and thermal fluctuation from sources ranging from the human body to the surroundings such as wind. Furthermore, it stably generates electric current even at elevated temperatures of 100 °C, relative humidity of 70%, and pH of 13 by virtue of its high Curie temperature and strong resistance for water and base. As proof of power generation under harsh environments, we demonstrate the generation of extremely high current at the exhaust pipe of a car, where hot CO and CO2 gases are rapidly expelled to air. This work expands the application of flexible PZT film-based NG for the scavenging mechanical vibration and thermal fluctuation energies even at extreme conditions.

  17. A prototype hybrid 7π quinone-fused 1,3,2-dithiazolyl radical.

    Science.gov (United States)

    Decken, A; Mailman, A; Passmore, J; Rautiainen, J M; Scherer, W; Scheidt, E-W

    2011-01-28

    Reaction of 1,4-naphthoquinone and SNSMF(6) (M = As, Sb) in SO(2) solution in a 1 : 2 molar ratio led to the naphthoquinone fused 1,3,2-dithiazolylium salts, 3MF(6) quantitatively by multinuclear NMR (87% isolated yield of 3SbF(6)) via the cycloaddition and oxidative dehydrogenation chemistry of SNS(+) with formation of NH(4)SbF(6) and S(8). The product 3SbF(6) was fully characterized by IR, Raman, multinuclear {(1)H, (13)C, (14)N} NMR, elemental analysis, cyclic voltammetry and single crystal X-ray crystallography. The reduction of 3SbF(6) with ferrocene (Cp(2)Fe) in refluxing acetonitrile (CH(3)CN) led to the first isolation of a fused quinone-thiazyl radical, 3˙ in 73% yield. The prototype hybrid quinone-thiazyl radical 3˙ was fully characterized by IR, Raman microscopy, EI-MS, elemental analysis, solution and solid state EPR, magnetic susceptibility (2-370 K) and was found to form π*-π* dimers in the solid state as determined by single crystal X-ray crystallography. Furthermore, the thermal decomposition of 3˙ led to a novel quinone-fused 1,2,3,4-tetrathiine, 10 (x = 2) and the known 1,2,5-thiadiazole, 11. The energetics of the cycloadditon and oxidative dehydrogenation chemistry of SNS(+) and 1,4-naphthoquinone leading to 3SbF(6) were estimated in the gas phase and SO(2) solution by DFT calculations (PBE0/6-311G(d)) and lattice enthalpies obtained by the volume based thermodynamic (VBT) approach in the solid state. The gas phase ion energetics (ionization potential (IP) and electron affinity (EA)) of 3˙ are compared to related 1,3,2- and 1,2,3-dithiazolyl radicals.

  18. Hybrid plasmachemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lelevkin, V. M., E-mail: lelevkin44@mail.ru; Smirnova, Yu. G.; Tokarev, A. V. [Kyrgyz-Russian Slavic University (Kyrgyzstan)

    2015-04-15

    A hybrid plasmachemical reactor on the basis of a dielectric barrier discharge in a transformer is developed. The characteristics of the reactor as functions of the dielectric barrier discharge parameters are determined.

  19. Comparative Transcriptional Profiling of Three Super-Hybrid Rice Combinations

    Directory of Open Access Journals (Sweden)

    Yonggang Peng

    2014-03-01

    Full Text Available Utilization of heterosis has significantly increased rice yields. However, its mechanism remains unclear. In this study, comparative transcriptional profiles of three super-hybrid rice combinations, LY2163, LY2186 and LYP9, at the flowering and filling stages, were created using rice whole-genome oligonucleotide microarray. The LY2163, LY2186 and LYP9 hybrids yielded 1193, 1630 and 1046 differentially expressed genes (DGs, accounting for 3.2%, 4.4% and 2.8% of the total number of genes (36,926, respectively, after using the z-test (p < 0.01. Functional category analysis showed that the DGs in each hybrid combination were mainly classified into the carbohydrate metabolism and energy metabolism categories. Further analysis of the metabolic pathways showed that DGs were significantly enriched in the carbon fixation pathway (p < 0.01 for all three combinations. Over 80% of the DGs were located in rice quantitative trait loci (QTLs of the Gramene database, of which more than 90% were located in the yield related QTLs in all three combinations, which suggested that there was a correlation between DGs and rice heterosis. Pathway Studio analysis showed the presence of DGs in the circadian regulatory network of all three hybrid combinations, which suggested that the circadian clock had a role in rice heterosis. Our results provide information that can help to elucidate the molecular mechanism underlying rice heterosis.

  20. Parallel Implementation of Gamma-Point Pseudopotential Plane-Wave DFT with Exact Exchange

    International Nuclear Information System (INIS)

    Bylaska, Eric J.; Tsemekhman, Kiril L.; Baden, Scott B.; Weare, John H.; Jonsson, Hannes

    2011-01-01

    One of the more persistent failures of conventional density functional theory (DFT) methods has been their failure to yield localized charge states such as polarons, excitons and solitons in solid-state and extended systems. It has been suggested that conventional DFT functionals, which are not self-interaction free, tend to favor delocalized electronic states since self-interaction creates a Coulomb barrier to charge localization. Pragmatic approaches in which the exchange correlation functionals are augmented with small amount of exact exchange (hybrid-DFT, e.g. B3LYP and PBE0) have shown promise in localizing charge states and predicting accurate band gaps and reaction barriers. We have developed a parallel algorithm for implementing exact exchange into pseudopotential plane-wave density functional theory and we have implemented it in the NWChem program package. The technique developed can readily be employed in plane-wave DFT programs. Furthermore, atomic forces and stresses are straightforward to implement, making it applicable to both confined and extended systems, as well as to Car-Parrinello ab initio molecular dynamic simulations. This method has been applied to several systems for which conventional DFT methods do not work well, including calculations for band gaps in oxides and the electronic structure of a charge trapped state in the Fe(II) containing mica, annite.

  1. Hybridization and genome evolution I: The role of contingency during hybrid speciation

    Directory of Open Access Journals (Sweden)

    Fabrice EROUKHMANOFF, Richard I. BAILEY, Glenn-Peter SæTRE

    2013-10-01

    Full Text Available Homoploid hybrid speciation (HHS involves the recombination of two differentiated genomes into a novel, functional one without a change in chromosome number. Theoretically, there are numerous ways for two parental genomes to recombine. Hence, chance may play a large role in the formation of a hybrid species. If these genome combinations can evolve rapidly following hybridization and sympatric situations are numerous, recurrent homoploid hybrid speciation is a possibility. We argue that three different, but not mutually exclusive, types of contingencies could influence this process. First, many of these “hopeful monsters” of recombinant parent genotypes would likely have low fitness. Only specific combinations of parental genomic contributions may produce viable, intra-fertile hybrid species able to accommodate potential constraints arising from intragenomic conflict. Second, ecological conditions (competition, geography of the contact zones or the initial frequency of both parent species might favor different outcomes ranging from sympatric coexistence to the formation of hybrid swarms and ultimately hybrid speciation. Finally, history may also play an important role in promoting or constraining recurrent HHS if multiple hybridization events occur sequentially and parental divergence or isolation differs along this continuum. We discuss under which conditions HHS may occur multiple times in parallel and to what extent recombination and selection may fuse the parent genomes in the same or different ways. We conclude by examining different approaches that might help to solve this intriguing evolutionary puzzle [Current Zoology 59 (5: 667-674, 2013]. 

  2. Towers of hybrid mesons

    International Nuclear Information System (INIS)

    Semay, Claude; Buisseret, Fabien; Silvestre-Brac, Bernard

    2009-01-01

    A hybrid meson is a quark-antiquark pair in which, contrary to ordinary mesons, the gluon field is in an excited state. In the framework of constituent models, the interaction potential is assumed to be the energy of an excited string. An approximate, but accurate, analytical solution of the Schroedinger equation with such a potential is presented. When applied to hybrid charmonia and bottomonia, towers of states are predicted in which the masses are a linear function of a harmonic oscillator band number for the quark-antiquark pair. Such a formula could be a reliable guide for the experimental detection of heavy hybrid mesons.

  3. and chebyshev functions

    Directory of Open Access Journals (Sweden)

    Mohsen Razzaghi

    2000-01-01

    Full Text Available A direct method for finding the solution of variational problems using a hybrid function is discussed. The hybrid functions which consist of block-pulse functions plus Chebyshev polynomials are introduced. An operational matrix of integration and the integration of the cross product of two hybrid function vectors are presented and are utilized to reduce a variational problem to the solution of an algebraic equation. Illustrative examples are included to demonstrate the validity and applicability of the technique.

  4. Research of a hybrid undulator

    International Nuclear Information System (INIS)

    Ma Youwu; Wu Bing; Liu Bo

    1995-12-01

    A 1.5 m tapered hybrid undulator has been designed and built for mid-infrared free electron laser experiments at CIAE. The undulator utilizes the REC-steel hybrid configuration. The magnetic gap and magnetic field taper can be continuously adjusted. The rms error of the peak field is less than 0.53%. The electron trajectory deviation is around 0.03 mm. The design of undulator, sorting of magnets in hybrid undulator using simulated annealing technique, the motion of electron beam in the ideal and measured magnetic field, magnetic field measurement technique and magnetic field adjustment are described. (6 refs., 10 figs., 1 tab)

  5. A modular function architecture for adaptive and predictive energy management in hybrid electric vehicles; Eine modulare Funktionsarchitektur fuer adaptives und vorausschauendes Energiemanagement in Hybridfahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, Andreas

    2009-10-27

    Due to the relatively low energy density of electrical energy storage devices, the control strategy of hybrid electric vehicles has to fulfil a variety of requirements in order to provide both, the availability of hybrid functions, and their efficient execution. Energy consuming functions such as electric drive or electric boost need a high amount of energy stored in the battery. On the other hand for the optimum use of the energy regeneration function a lower state of charge is preferable in order to enable storage of the kinetic energy of the vehicle in all situations, including upon deceleration from high speeds or downhill driving. These diverging requirements yield a conflict of objectives for the charging strategy of hybrid electric vehicles. This work proposes a way to overcome the restrictions on efficiency in hybrid electric vehicles without deteriorating overall driving performance by charging or discharging the traction battery, and by setting the energy management parametres according to the current and forthcoming driving situation. Specific charging and electric drive strategies are presented for various driving situations which are identified by sensors such as navigation systems, cameras or radar. Necessary sensor data fusion methods for driving situation identification are described and a modular function architecture for predictive energy management is derived that is plug-and-play compatible with a broad fleet of vehicles. In order to evaluate its potential, this work also focuses on the simulation of the energy functions and their implementation into an experimental vehicle. This allows measurements under real traffic conditions and a sensivity analysis of the main module interactions within the architecture. (orig.)

  6. Suitable Fundamental Properties of Ta0.75V0.25ON Material for Visible-Light-Driven Photocatalysis: A DFT Study

    KAUST Repository

    Harb, Moussab; Cavallo, Luigi

    2016-01-01

    By applying calculations based on density functional theory, and on density functional perturbation theory, together with generalized gradient approximation-Perdew–Burke–Emzerho and screened Coulomb hybrid HSE06 functionals, we predict novel and suitable fundamental parameters of the stable monoclinic Ta0.75V0.25ON semiconductor for solar water splitting. In addition to its predicted bandgap of 2.0 eV in the required zone for solar-driven water splitting, this material reveals a high visible-light absorption coefficient, high static dielectric constant, high hole and electron mobilities along the [001] and [010] crystallographic directions, relatively low exciton binding energy, and suitable band edge energy levels for oxidizing water and reducing protons. The optical, charge-carrier transport, and redox features predicted for this material are found to be considerably better than those obtained for Ta3N5, which is the most common semiconductor photocatalyst used in visible-light-driven water splitting.

  7. Suitable Fundamental Properties of Ta0.75V0.25ON Material for Visible-Light-Driven Photocatalysis: A DFT Study

    KAUST Repository

    Harb, Moussab

    2016-11-29

    By applying calculations based on density functional theory, and on density functional perturbation theory, together with generalized gradient approximation-Perdew–Burke–Emzerho and screened Coulomb hybrid HSE06 functionals, we predict novel and suitable fundamental parameters of the stable monoclinic Ta0.75V0.25ON semiconductor for solar water splitting. In addition to its predicted bandgap of 2.0 eV in the required zone for solar-driven water splitting, this material reveals a high visible-light absorption coefficient, high static dielectric constant, high hole and electron mobilities along the [001] and [010] crystallographic directions, relatively low exciton binding energy, and suitable band edge energy levels for oxidizing water and reducing protons. The optical, charge-carrier transport, and redox features predicted for this material are found to be considerably better than those obtained for Ta3N5, which is the most common semiconductor photocatalyst used in visible-light-driven water splitting.

  8. Hybrid materials for optics and photonics.

    Science.gov (United States)

    Lebeau, Benedicte; Innocenzi, Plinio

    2011-02-01

    The interest in organic-inorganic hybrids as materials for optics and photonics started more than 25 years ago and since then has known a continuous and strong growth. The high versatility of sol-gel processing offers a wide range of possibilities to design tailor-made materials in terms of structure, texture, functionality, properties and shape modelling. From the first hybrid material with optical functional properties that has been obtained by incorporation of an organic dye in a silica matrix, the research in the field has quickly evolved towards more sophisticated systems, such as multifunctional and/or multicomponent materials, nanoscale and self-assembled hybrids and devices for integrated optics. In the present critical review, we have focused our attention on three main research areas: passive and active optical hybrid sol-gel materials, and integrated optics. This is far from exhaustive but enough to give an overview of the huge potential of these materials in photonics and optics (254 references).

  9. Laser driven fusion fission hybrids

    International Nuclear Information System (INIS)

    Hansen, L.F.; Maniscalco, J.A.

    1977-11-01

    The role of the fusion-fission hybrid reactor (FFHR) as a fissile fuel and/or power producer is discussed. As long range options to supply the world energy needs, hybrid-fueled thermal-burner reactors are compared to liquid metal fast breeder reactors (LMFBR). A discussion of different fuel cycles (thorium, depleted uranium, and spent fuel) is presented in order to compare the energy multiplication, the production of fissile fuel, the laser efficiency and pellet gain requirements of the hybrid reactor. Lawrence Livermore Laboratory (LLL) has collaborated with Bechtel Corporation and with Westinghouse in two engineering design studies of laser fusion driven hybrid power plants. The hybrid designs which have resulted from these two studies are briefly described and analyzed by considering operational parameters, such as energy multiplication, power density, burn-up and plutonium production as a function time

  10. A PDMS/paper/glass hybrid microfluidic biochip integrated with aptamer-functionalized graphene oxide nano-biosensors for one-step multiplexed pathogen detection.

    Science.gov (United States)

    Zuo, Peng; Li, XiuJun; Dominguez, Delfina C; Ye, Bang-Ce

    2013-10-07

    Infectious pathogens often cause serious public health concerns throughout the world. There is an increasing demand for simple, rapid and sensitive approaches for multiplexed pathogen detection. In this paper we have developed a polydimethylsiloxane (PDMS)/paper/glass hybrid microfluidic system integrated with aptamer-functionalized graphene oxide (GO) nano-biosensors for simple, one-step, multiplexed pathogen detection. The paper substrate used in this hybrid microfluidic system facilitated the integration of aptamer biosensors on the microfluidic biochip, and avoided complicated surface treatment and aptamer probe immobilization in a PDMS or glass-only microfluidic system. Lactobacillus acidophilus was used as a bacterium model to develop the microfluidic platform with a detection limit of 11.0 cfu mL(-1). We have also successfully extended this method to the simultaneous detection of two infectious pathogens - Staphylococcus aureus and Salmonella enterica. This method is simple and fast. The one-step 'turn on' pathogen assay in a ready-to-use microfluidic device only takes ~10 min to complete on the biochip. Furthermore, this microfluidic device has great potential in rapid detection of a wide variety of different other bacterial and viral pathogens.

  11. Hybrid variational principles and synthesis method for finite element neutron transport calculations

    International Nuclear Information System (INIS)

    Ackroyd, R.T.; Nanneh, M.M.

    1990-01-01

    A family of hybrid variational principles is derived using a generalised least squares method. Neutron conservation is automatically satisfied for the hybrid principles employing two trial functions. No interfaces or reflection conditions need to be imposed on the independent even-parity trial function. For some hybrid principles a single trial function can be employed by relating one parity trial function to the other, using one of the parity transport equation in relaxed form. For other hybrid principles the trial functions can be employed sequentially. Synthesis of transport solutions, starting with the diffusion theory approximation, has been used as a way of reducing the scale of the computation that arises with established finite element methods for neutron transport. (author)

  12. Description of the Charge Transfer States at the Pentacene/C60 Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

    KAUST Repository

    Zheng, Zilong

    2016-06-24

    Density functional theory (DFT) approaches based on range-separated hybrid functionals are currently methods of choice for the description of the charge-transfer (CT) states in organic donor/acceptor solar cells. However, these calculations are usually performed on small-size donor/acceptor complexes and as result do not account for electronic polarization effects. Here, using a pentacene/C60 complex as a model system, we discuss the ability of long-range corrected (LCR) hybrid functionals in combination with the polarizable continuum model (PCM) to determine the impact of the solid-state environment on the CT states. The CT energies are found to be insensitive to the interactions with the dielectric medium when a conventional time-dependent DFT/PCM (TDDFT/PCM) approach is used. However, a decrease in the energy of the CT state in the framework of LRC functionals can be obtained by using a smaller range-separated parameter when going from an isolated donor/acceptor complex to the solid-state case.

  13. Na3Si2Y0.16Zr1.84PO12-ionic liquid hybrid electrolytes: An approach for realizing solid-state sodium-ion batteries?

    Science.gov (United States)

    de la Torre-Gamarra, Carmen; Appetecchi, Giovanni Battista; Ulissi, Ulderico; Varzi, Alberto; Varez, Alejandro; Passerini, Stefano

    2018-04-01

    Ceramic electrolytes are prepared through sintering processes which are carried out at high temperatures and require prolonged operating times, resulting unwelcome in industrial applications. We report a physicochemical characterization on hybrid, sodium conducting, electrolyte systems obtained by coating NASICON ceramic powders with the N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid. The goal is to realize a ceramic-IL interface with improved sodium mobility, aiming to obtain a solid electrolyte with high ion transport properties but avoiding sintering thermal treatment. The purpose of the present work, however, is showing how simply combining NASICON powder and Py14TFSI does not lead to any synergic effect on the resulting hybrid electrolyte, evidencing that an average functionalization of the ceramic powder surface and/or ionic liquid is needed. Also, the processing conditions for preparing the hybrid samples are found to affect their ion transport properties.

  14. Effects of van der Waals density functional corrections on trends in furfural adsorption and hydrogenation on close-packed transition metal surfaces

    Science.gov (United States)

    Liu, Bin; Cheng, Lei; Curtiss, Larry; Greeley, Jeffrey

    2014-04-01

    The hydrogenation of furfural to furfuryl alcohol on Pd(111), Cu(111) and Pt(111) is studied with both standard Density Functional Theory (DFT)-GGA functionals and with van der Waals-corrected density functionals. VdW-DF functionals, including optPBE, optB88, optB86b, and Grimme's method, are used to optimize the adsorption configurations of furfural, furfuryl alcohol, and related intermediates resulting from hydrogenation of furfural, and the results are compared to corresponding values determined with GGA functionals, including PW91 and PBE. On Pd(111) and Pt(111), the adsorption geometries of the intermediates are not noticeably different between the two classes of functionals, while on Cu(111), modest changes are seen in both the perpendicular distance and the orientation of the aromatic ring with respect to the planar surface. In general, the binding energies increase substantially in magnitude as a result of van der Waals contributions on all metals. In contrast, however, dispersion effects on the kinetics of hydrogenation are relatively small. It is found that activation barriers are not significantly affected by the inclusion of dispersion effects, and a Brønsted-Evans-Polanyi relationship developed solely from PW91 calculations on Pd(111) is capable of describing corresponding results on Cu(111) and Pt(111), even when the dispersion effects are included. Finally, the reaction energies and barriers derived from the dispersion-corrected and pure GGA calculations are used to plot simple potential energy profiles for furfural hydrogenation to furfuryl alcohol on the three considered metals, and an approximately constant downshift of the energetics due to the dispersion corrections is observed.

  15. CNR considerations for rapid real-time MRI tumor tracking in radiotherapy hybrid devices: Effects of B0 field strength

    International Nuclear Information System (INIS)

    Wachowicz, K.; De Zanche, N.; Yip, E.; Volotovskyy, V.; Fallone, B. G.

    2016-01-01

    Purpose: This work examines the subject of contrast-to-noise ratio (CNR), specifically between tumor and tissue background, and its dependence on the MRI field strength, B 0 . This examination is motivated by the recent interest and developments in MRI/radiotherapy hybrids where real-time imaging can be used to guide treatment beams. The ability to distinguish a tumor from background tissue is of primary importance in this field, and this work seeks to elucidate the complex relationship between the CNR and B 0 that is too often assumed to be purely linear. Methods: Experimentally based models of B 0 -dependant relaxation for various tumor and normal tissues from the literature were used in conjunction with signal equations for MR sequences suitable for rapid real-time imaging to develop field-dependent predictions for CNR. These CNR models were developed for liver, lung, breast, glioma, and kidney tumors for spoiled gradient-echo, balanced steady-state free precession (bSSFP), and single-shot half-Fourier fast spin echo sequences. Results: Due to the pattern in which the relaxation properties of tissues are found to vary over B 0 field (specifically the T 1 time), there was always an improved CNR at lower fields compared to linear dependency. Further, in some tumor sites, the CNR at lower fields was found to be comparable to, or sometimes higher than those at higher fields (i.e., bSSFP CNR for glioma, kidney, and liver tumors). Conclusions: In terms of CNR, lower B 0 fields have been shown to perform as well or better than higher fields for some tumor sites due to superior T 1 contrast. In other sites this effect was less pronounced, reversing the CNR advantage. This complex relationship between CNR and B 0 reveals both low and high magnetic fields as viable options for tumor tracking in MRI/radiotherapy hybrids.

  16. Functional Carbon Nanotube/Mesoporous Carbon/MnO2 Hybrid Network for High-Performance Supercapacitors

    Directory of Open Access Journals (Sweden)

    Tao Tao

    2014-01-01

    Full Text Available A functional carbon nanotube/mesoporous carbon/MnO2 hybrid network has been developed successfully through a facile route. The resulting composites exhibited a high specific capacitance of 351 F/g at 1 A g−1, with intriguing charge/discharge rate performance and cycling stability due to a synergistic combination of large surface area and excellent electron-transport capabilities of MnO2 with the good conductivity of the carbon nanotube/mesoporous carbon networks. Such composite shows great potential to be used as electrodes for supercapacitors.

  17. Validation of missed space-group symmetry in X-ray powder diffraction structures with dispersion-corrected density functional theory.

    Science.gov (United States)

    Hempler, Daniela; Schmidt, Martin U; van de Streek, Jacco

    2017-08-01

    More than 600 molecular crystal structures with correct, incorrect and uncertain space-group symmetry were energy-minimized with dispersion-corrected density functional theory (DFT-D, PBE-D3). For the purpose of determining the correct space-group symmetry the required tolerance on the atomic coordinates of all non-H atoms is established to be 0.2 Å. For 98.5% of 200 molecular crystal structures published with missed symmetry, the correct space group is identified; there are no false positives. Very small, very symmetrical molecules can end up in artificially high space groups upon energy minimization, although this is easily detected through visual inspection. If the space group of a crystal structure determined from powder diffraction data is ambiguous, energy minimization with DFT-D provides a fast and reliable method to select the correct space group.

  18. Combining motor imagery with selective sensation toward a hybrid-modality BCI.

    Science.gov (United States)

    Yao, Lin; Meng, Jianjun; Zhang, Dingguo; Sheng, Xinjun; Zhu, Xiangyang

    2014-08-01

    A hybrid modality brain-computer interface (BCI) is proposed in this paper, which combines motor imagery with selective sensation to enhance the discrimination between left and right mental tasks, e.g., the classification between left/ right stimulation sensation and right/ left motor imagery. In this paradigm, wearable vibrotactile rings are used to stimulate both the skin on both wrists. Subjects are required to perform the mental tasks according to the randomly presented cues (i.e., left hand motor imagery, right hand motor imagery, left stimulation sensation or right stimulation sensation). Two-way ANOVA statistical analysis showed a significant group effect (F (2,20) = 7.17, p = 0.0045), and the Benferroni-corrected multiple comparison test (with α = 0.05) showed that the hybrid modality group is 11.13% higher on average than the motor imagery group, and 10.45% higher than the selective sensation group. The hybrid modality experiment exhibits potentially wider spread usage within ten subjects crossed 70% accuracy, followed by four subjects in motor imagery and five subjects in selective sensation. Six subjects showed statistically significant improvement ( Benferroni-corrected) in hybrid modality in comparison with both motor imagery and selective sensation. Furthermore, among subjects having difficulties in both motor imagery and selective sensation, the hybrid modality improves their performance to 90% accuracy. The proposed hybrid modality BCI has demonstrated clear benefits for those poorly performing BCI users. Not only does the requirement of motor and sensory anticipation in this hybrid modality provide basic function of BCI for communication and control, it also has the potential for enhancing the rehabilitation during motor recovery.

  19. Analysis of Spo0M function in Bacillus subtilis.

    Directory of Open Access Journals (Sweden)

    Luz Adriana Vega-Cabrera

    Full Text Available Spo0M has been previously reported as a regulator of sporulation in Bacillus subtilis; however, little is known about the mechanisms through which it participates in sporulation, and there is no information to date that relates this protein to other processes in the bacterium. In this work we present evidence from proteomic, protein-protein interaction, morphological, subcellular localization microscopy and bioinformatics studies which indicate that Spo0M function is not necessarily restricted to sporulation, and point towards its involvement in other stages of the vegetative life cycle. In the current study, we provide evidence that Spo0M interacts with cytoskeletal proteins involved in cell division, which suggest a function additional to that previously described in sporulation. Spo0M expression is not restricted to the transition phase or sporulation; rather, its expression begins during the early stages of growth and Spo0M localization in B. subtilis depends on the bacterial life cycle and could be related to an additional proposed function. This is supported by our discovery of homologs in a broad distribution of bacterial genera, even in non-sporulating species. Our work paves the way for re-evaluation of the role of Spo0M in bacterial cell.

  20. Novel acid-base hybrid membrane based on amine-functionalized reduced graphene oxide and sulfonated polyimide for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Cao, Li; Sun, Qingqing; Gao, Yahui; Liu, Luntao; Shi, Haifeng

    2015-01-01

    A series of novel acid-base hybrid membranes (SPI/PEI-rGO) based on sulfonated polyimide (SPI) with polyethyleneimine-functionalized reduced graphene oxide (PEI-rGO) are prepared by a solution-casting method for vanadium redox flow battery (VRB). FT-IR and XPS results prove the successful fabrication of PEI-rGO and SPI/PEI-rGO hybrid membranes, which show a dense and homogeneous structure observed by SEM. The physicochemical properties such as water uptake, swelling ratio, ion exchange capacity, proton conductivity and vanadium ion permeability are well controlled by the incorporated PEI-rGO fillers. The interfacial-formed acid-base pairs between PEI-rGO and SPI matrix effectively reduce the swelling ratio and vanadium ion permeability, increasing the stability performance of the hybrid membranes. SPI/PEI-rGO-2 hybrid membrane exhibits a higher coulombic efficiency (CE, 95%) and energy efficiency (EE, 75.6%) at 40 mA cm −2 , as compared with Nafion 117 membrane (CE, 91% and EE, 66.8%). The self-discharge time of the VRB with SPI/PEI-rGO-2 hybrid membrane (80 h) is longer than that of Nafion 117 membrane (26 h), demonstrating the excellent blocking ability for vanadium ion. After 100 charge-discharge cycles, SPI/PEI-rGO-2 membrane exhibits the good stability under strong oxidizing and acid condition, proving that SPI/PEI-rGO acid-base hybrid membranes could be used as the promising candidates for VRB applications

  1. Graphene hybridization for energy storage applications.

    Science.gov (United States)

    Li, Xianglong; Zhi, Linjie

    2018-05-08

    Graphene has attracted considerable attention due to its unique two-dimensional structure, high electronic mobility, exceptional thermal conductivity, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. To meet the ever increasing demand for portable electronic products, electric vehicles, smart grids, and renewable energy integrations, hybridizing graphene with various functions and components has been demonstrated to be a versatile and powerful strategy to significantly enhance the performance of various energy storage systems such as lithium-ion batteries, supercapacitors and beyond, because such hybridization can result in synergistic effects that combine the best merits of involved components and confer new functions and properties, thereby improving the charge/discharge efficiencies and capabilities, energy/power densities, and cycle life of these energy storage systems. This review will focus on diverse graphene hybridization principles and strategies for energy storage applications, and the proposed outline is as follows. First, graphene and its fundamental properties, followed by graphene hybrids and related hybridization motivation, are introduced. Second, the developed hybridization formulas of using graphene for lithium-ion batteries are systematically categorized from the viewpoint of material structure design, bulk electrode construction, and material/electrode collaborative engineering; the latest representative progress on anodes and cathodes of lithium-ion batteries will be reviewed following such classifications. Third, similar hybridization formulas for graphene-based supercapacitor electrodes will be summarized and discussed as well. Fourth, the recently emerging hybridization formulas for other graphene-based energy storage devices will be briefed in combination with typical examples. Finally, future prospects and directions on the exploration of graphene hybridization toward the design and construction of

  2. Accurate Experimental and Theoretical Enthalpies of Association of TiCl4 with Typical Lewis Bases Used in Heterogeneous Ziegler-Natta Catalysis

    KAUST Repository

    Credendino, Raffaele

    2017-09-18

    Adducts of TiCl4 with Lewis bases used as internal or external donors in heterogeneous Ziegler-Natta (ZN) catalysis represents a fundamental interaction contributing to the final composition of MgCl2 supported ZN-catalysts. This study presents the accurate experimental evaluation, from titration calorimetry, of the formation enthalpy of TiCl4 adducts with 15 Lewis bases of industrial interests. In addition, we report accurate energies of association of TiCl4 with the same Lewis bases from calculations at the DLPNO-CCSD(T) level of theory. These accurate experimental and theoretical association values are compared with selected methods based on density functional theory (DFT) in combination with popular continuum solvation models. Calculations suggest that the PBE-D3, and M06 functionals in combination with a triple-ζ plus polarization quality basis set provide the best performance when the basis set superposition error (BSSE) is not removed from the association energies. Cleaning the association energies by the BSSE with the counterpoise protocol suggests the B3LYP-D3, TPSS-D3 and M06L as the best performing functionals. Introducing solvent effects with the PCM and SMD continuum solvation models allows comparing the DFT based association enthalpies with the experimental values obtained from titration calorimetry. Both solvation models in combination with the PBE-D3, PBE0-D3, B3LYP-D3, TPSS-D3, M06L, and M06 functionals provide association enthalpies close to the experimental values with MUEs in range 10 – 15 kJ/mol.

  3. Density-functional theory computer simulations of CZTS0.25Se0.75 alloy phase diagrams

    International Nuclear Information System (INIS)

    Chagarov, E.; Sardashti, K.; Kummel, A. C.; Haight, R.; Mitzi, D. B.

    2016-01-01

    Density-functional theory simulations of CZTS, CZTSe, and CZTS 0.25 Se 0.75 photovoltaic compounds have been performed to investigate the stability of the CZTS 0.25 Se 0.75 alloy vs. decomposition into CZTS, CZTSe, and other secondary compounds. The Gibbs energy for vibrational contributions was estimated by calculating phonon spectra and thermodynamic properties at finite temperatures. It was demonstrated that the CZTS 0.25 Se 0.75 alloy is stabilized not by enthalpy of formation but primarily by the mixing contributions to the Gibbs energy. The Gibbs energy gains/losses for several decomposition reactions were calculated as a function of temperature with/without intermixing and vibration contributions to the Gibbs energy. A set of phase diagrams was built in the multidimensional space of chemical potentials at 300 K and 900 K temperatures to demonstrate alloy stability and boundary compounds at various chemical conditions. It demonstrated for CZTS 0.25 Se 0.75 that the chemical potentials for stability differ between typical processing temperature (∼900 K) and operating temperature (300 K). This implies that as cooling progresses, the flux/concentration of S should be increased in MBE growth to maintain the CZTS 0.25 Se 0.75 in a thermodynamically stable state to minimize phase decomposition.

  4. Density-functional theory computer simulations of CZTS0.25Se0.75 alloy phase diagrams

    Science.gov (United States)

    Chagarov, E.; Sardashti, K.; Haight, R.; Mitzi, D. B.; Kummel, A. C.

    2016-08-01

    Density-functional theory simulations of CZTS, CZTSe, and CZTS0.25Se0.75 photovoltaic compounds have been performed to investigate the stability of the CZTS0.25Se0.75 alloy vs. decomposition into CZTS, CZTSe, and other secondary compounds. The Gibbs energy for vibrational contributions was estimated by calculating phonon spectra and thermodynamic properties at finite temperatures. It was demonstrated that the CZTS0.25Se0.75 alloy is stabilized not by enthalpy of formation but primarily by the mixing contributions to the Gibbs energy. The Gibbs energy gains/losses for several decomposition reactions were calculated as a function of temperature with/without intermixing and vibration contributions to the Gibbs energy. A set of phase diagrams was built in the multidimensional space of chemical potentials at 300 K and 900 K temperatures to demonstrate alloy stability and boundary compounds at various chemical conditions. It demonstrated for CZTS0.25Se0.75 that the chemical potentials for stability differ between typical processing temperature (˜900 K) and operating temperature (300 K). This implies that as cooling progresses, the flux/concentration of S should be increased in MBE growth to maintain the CZTS0.25Se0.75 in a thermodynamically stable state to minimize phase decomposition.

  5. Solubility studies of inorganic–organic hybrid nanoparticle photoresists with different surface functional groups

    KAUST Repository

    Li, Li

    2016-01-01

    © 2016 The Royal Society of Chemistry. The solubility behavior of Hf and Zr based hybrid nanoparticles with different surface ligands in different concentrations of photoacid generator as potential EUV photoresists was investigated in detail. The nanoparticles regardless of core or ligand chemistry have a hydrodynamic diameter of 2-3 nm and a very narrow size distribution in organic solvents. The Hansen solubility parameters for nanoparticles functionalized with IBA and 2MBA have the highest contribution from the dispersion interaction than those with tDMA and MAA, which show more polar character. The nanoparticles functionalized with unsaturated surface ligands showed more apparent solubility changes after exposure to DUV than those with saturated ones. The solubility differences after exposure are more pronounced for films containing a higher amount of photoacid generator. The work reported here provides material selection criteria and processing strategies for the design of high performance EUV photoresists.

  6. Density functional theory study of hydrogenation mechanism in Fe-doped Mg(0 0 0 1) surface

    International Nuclear Information System (INIS)

    Wu Guangxin; Zhang Jieyu; Wu Yongquan; Li Qian; Chou Kuochih; Bao Xinhua

    2009-01-01

    Using density functional theory (DFT) in combination with nudged elastic band (NEB) method, the dissociative chemisorptions and diffusion processes of hydrogen on both pure and Fe-doped Mg(0 0 0 1) surfaces are studied. Firstly, the dissociation pathway of H 2 and the relative barrier were investigated. The calculated dissociation barrier (1.08 eV) of hydrogen molecule on a pure Mg(0 0 0 1) surface is in good agreement with comparable experimental and theoretical studies. For the Fe-doped Mg(0 0 0 1) surface, the activated barrier decreases to 0.101 eV due to the strong interaction between the s orbital of H and the d orbital of Fe. Then, the diffusion processes of atomic hydrogen on pure and Fe-doped Mg(0 0 0 1) are presented. The obtained diffusion barrier to the first subsurface is 0.45 eV and 0.98 eV, respectively. Finally, Chou method was used to investigate the hydrogen sorption kinetic mechanism of pure MgH 2 and Mg mixed with 5 at.% Fe atoms composites. The obtained activation energies are 0.87 ± 0.02 and 0.31 ± 0.01 eV for H 2 dissociation on the pure surface and H atom diffusion in Fe-doped Mg surfaces, respectively. It suggests that the rate-controlling step is dissociation of H 2 on the pure Mg surface while it is diffusion of H atom in the Fe-doped Mg surface. And both of fitting data are matching well with our calculation results.

  7. Fuzzy Shannon Entropy: A Hybrid GIS-Based Landslide Susceptibility Mapping Method

    Directory of Open Access Journals (Sweden)

    Majid Shadman Roodposhti

    2016-09-01

    Full Text Available Assessing Landslide Susceptibility Mapping (LSM contributes to reducing the risk of living with landslides. Handling the vagueness associated with LSM is a challenging task. Here we show the application of hybrid GIS-based LSM. The hybrid approach embraces fuzzy membership functions (FMFs in combination with Shannon entropy, a well-known information theory-based method. Nine landslide-related criteria, along with an inventory of landslides containing 108 recent and historic landslide points, are used to prepare a susceptibility map. A random split into training (≈70% and testing (≈30% samples are used for training and validation of the LSM model. The study area—Izeh—is located in the Khuzestan province of Iran, a highly susceptible landslide zone. The performance of the hybrid method is evaluated using receiver operating characteristics (ROC curves in combination with area under the curve (AUC. The performance of the proposed hybrid method with AUC of 0.934 is superior to multi-criteria evaluation approaches using a subjective scheme in this research in comparison with a previous study using the same dataset through extended fuzzy multi-criteria evaluation with AUC value of 0.894, and was built on the basis of decision makers’ evaluation in the same study area.

  8. Application of Hybrid Genetic Algorithm Routine in Optimizing Food and Bioengineering Processes

    Directory of Open Access Journals (Sweden)

    Jaya Shankar Tumuluru

    2016-11-01

    Full Text Available Optimization is a crucial step in the analysis of experimental results. Deterministic methods only converge on local optimums and require exponentially more time as dimensionality increases. Stochastic algorithms are capable of efficiently searching the domain space; however convergence is not guaranteed. This article demonstrates the novelty of the hybrid genetic algorithm (HGA, which combines both stochastic and deterministic routines for improved optimization results. The new hybrid genetic algorithm developed is applied to the Ackley benchmark function as well as case studies in food, biofuel, and biotechnology processes. For each case study, the hybrid genetic algorithm found a better optimum candidate than reported by the sources. In the case of food processing, the hybrid genetic algorithm improved the anthocyanin yield by 6.44%. Optimization of bio-oil production using HGA resulted in a 5.06% higher yield. In the enzyme production process, HGA predicted a 0.39% higher xylanase yield. Hybridization of the genetic algorithm with a deterministic algorithm resulted in an improved optimum compared to statistical methods.

  9. The Incomplete Conditional Stellar Mass Function: Unveiling the Stellar Mass Functions of Galaxies at 0.1 < Z < 0.8 from BOSS Observations

    Science.gov (United States)

    Guo, Hong; Yang, Xiaohu; Lu, Yi

    2018-05-01

    We propose a novel method to constrain the missing fraction of galaxies using galaxy clustering measurements in the galaxy conditional stellar mass function (CSMF) framework, which is applicable to surveys that suffer significantly from sample selection effects. The clustering measurements, which are not sensitive to the random sampling (missing fraction) of galaxies, are widely used to constrain the stellar–halo mass relation (SHMR). By incorporating a missing fraction (incompleteness) component into the CSMF model (ICSMF), we use the incomplete stellar mass function and galaxy clustering to simultaneously constrain the missing fractions and the SHMRs. Tests based on mock galaxy catalogs with a few typical missing fraction models show that this method can accurately recover the missing fraction and the galaxy SHMR, hence providing us with reliable measurements of the galaxy stellar mass functions. We then apply it to the Baryon Oscillation Spectroscopic Survey (BOSS) over the redshift range of 0.1 1011 M ⊙. We find that the sample completeness for BOSS is over 80% at z account, we provide accurate measurements of the stellar mass functions for galaxies with {10}11 {M}ȯ < {M}* < {10}12 {M}ȯ , as well as the SHMRs, over the redshift range 0.1 < z < 0.8 in this largest galaxy redshift survey.

  10. Microwave irradiation controls the manganese oxidation states of nanostructured (Li[Li0.2Mn0.52Ni0.13Co0.13Al0.02]O2) layered cathode materials for high-performance lithium ion batteries

    CSIR Research Space (South Africa)

    Jafta, CJ

    2015-02-01

    Full Text Available A hybrid synthesis procedure, combining microwave irradiation and conventional annealing process, is described for the preparation of lithium-rich manganese-rich cathode materials, Li[Li0.2Mn0.54Ni0.13Co0.13]O2 (LMNC) and its aluminum...

  11. Anticorrosive organic/inorganic hybrid coatings

    Science.gov (United States)

    Gao, Tongzhai

    Organic/inorganic hybrid coating system was developed for anticorrosion applications using polyurea, polyurethane or epoxide as the organic phase and polysiloxane, formed by sol-gel process, as the inorganic phase. Polyurea/polysiloxane hybrid coatings were formulated and moisture cured using HDI isocyanurate, alkoxysilane-functionalized HDI isocyanurate, and tetraethyl orthosilicate (TEOS) oligomers. Two urethanes were prepared using the same components as abovementioned in addition to the oligoesters derived from either cyclohexane diacids (CHDA) and 2-butyl-2-ethyl-1,3-propanediol (BEPD) or adipic acid (AA), isophthalic acid (IPA), 1,6-hexanediol (HD), and trimethylol propane (TMP). Accelerated weathering and outdoor exposure were performed to study the weatherability of the polyurethane/polysiloxane hybrid coating system. FTIR and solid-state 13C NMR revealed that the degradation of the hybrid coatings occurred at the urethane and ester functionalities of the organic phase. DMA and DSC analyses showed the glass transition temperature increased and broadened after weathering. SEM was employed to observe the change of morphology of the hybrid coatings and correlated with the gloss variation after weathering. Rutile TiO2 was formulated into polyurethane/polysiloxane hybrid coatings in order to investigate the effect of pigmentation on the coating properties and the sol-gel precursor. Chemical interaction between the TiO2 and the sol-gel precursor was investigated using solid-state 29Si NMR and XPS. The morphology, mechanical, viscoelastic, thermal properties of the pigmented coatings were evaluated as a function of pigmentation volume concentration (PVC). Using AFM and SEM, the pigment were observed to be well dispersed in the polymer matrix. The thermal stability, the tensile modulus and strength of the coatings were enhanced with increasing PVC, whereas the pull-off adhesion and flexibility were reduced with increasing PVC. Finally, the pigmented coatings were

  12. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies.

    Science.gov (United States)

    Patil, Avinash J; Li, Mei; Mann, Stephen

    2013-08-21

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of "inorganic molecular wrapping" of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as "armour-plated" enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  13. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies

    Science.gov (United States)

    Patil, Avinash J.; Li, Mei; Mann, Stephen

    2013-07-01

    Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of ``inorganic molecular wrapping'' of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as ``armour-plated'' enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.

  14. Comprehensive Benefit Evaluation of the Wind-PV-ES and Transmission Hybrid Power System Consideration of System Functionality and Proportionality

    Directory of Open Access Journals (Sweden)

    Huizheng Ji

    2017-01-01

    Full Text Available In the background of decreasing fossil fuels and increasing environmental pollution, the wind-photovoltaic energy storage and transmission hybrid power system (or called the wind-PV-ES and transmission hybrid system has become a strategic choice to achieve energy sustainability. However, the comprehensive benefit evaluation of such a combined power system is in a relatively blank state in China, which will hinder the reasonable and orderly development of this station. Four parts, the technical performance, economic benefit, ecological impact and social benefit, are considered in this paper, and a multi-angle evaluation index system of the wind-PV-ES and transmission system is designed. The projection pursuit model is used to evaluated system functionality conventionally; relative entropy theory is used to evaluate the system functionality simultaneously; and a comprehensive benefit evaluation model of the technique for order preference by similar to ideal solution (TOPSIS considering both system functionality and proportionality is constructed. Finally, the national demonstration station of the wind-PV-ES-transmission system is taken as an example to testify to the practicability and validity of the evaluation index system and model.

  15. Modifikasi dan Uji Kinerja Alat Pengering Energi Surya-Hybrid Tipe Rak untuk Pengeringan Ikan Teri

    Directory of Open Access Journals (Sweden)

    Risman Hanafi

    2017-04-01

    Abstract. At the time of harvest fish, fishermen get a lot of anchovy as catches with very large amount. Due to the very large number of these, sometimes anchovy is not sold out. This resulted in an anchovy rot if not done preservation (cool storage. One way in which the fisherman is by drying anchovy naturally (the drying in the sun. A tool rack type solar dryer is a box-shaped dryer that utilize the sun as thermal energy. The constraints of this tool is only utilizing the heat from solar energy, so when the weather is cloudy or at nightfall these tools can not function. The research aims to modify the tool rack type solar dryer to be a hybrid dryer for drying anchovy. The results were obtained that total efficiency of energy use during drying is for drying empty test hybrid is 0,010%, for drying hybrid test at 0,695%, and for drying solar test of 20,319%. As for the length of drying time, hybrid test replicates 1 for 7 hours, hybrid test replicates 2 for 8 hours, solar test replicates 1 for 10 hours, and solar test replicates 2 for 11 hours. For the total energy available, hybrid drying of 305,838 MJ and solar drying of 9,896 MJ.

  16. Dietary supplementation with hybrid palm oil alters liver function in the common Marmoset.

    Science.gov (United States)

    Spreafico, Flavia; Sales, Rafael Carvalho; Gil-Zamorano, Judit; Medeiros, Priscylla da Costa; Latasa, Maria-Jesús; Lima, Monique Ribeiro; de Souza, Sergio Augusto Lopes; Martin-Hernández, Roberto; Gómez-Coronado, Diego; Iglesias-Gutierrez, Eduardo; Mantilla-Escalante, Diana C; das Graças Tavares do Carmo, Maria; Dávalos, Alberto

    2018-02-09

    Hybrid palm oil, which contains higher levels of oleic acid and lower saturated fatty acids in comparison with African palm oil, has been proposed to be somehow equivalent to extra virgin olive oil. However, the biological effects of its consumption are poorly described. Here we have explored the effects of its overconsumption on lipid metabolism in a non-human primate model, the common marmoset. Dietary supplementation of marmoset with hyperlipidic diet containing hybrid palm oil for 3 months did not modify plasma lipids levels, but increased glucose levels as compared to the supplementation with African palm oil. Liver volume was unexpectedly found to be more increased in marmosets consuming hybrid palm oil than in those consuming African palm oil. Hepatic total lipid content and circulating transaminases were dramatically increased in animals consuming hybrid palm oil, as well as an increased degree of fibrosis. Analysis of liver miRNAs showed a selective modulation of certain miRNAs by hybrid palm oil, some of which were predicted to target genes involved in cell adhesion molecules and peroxisomal pathways. Our data suggest that consumption of hybrid palm oil should be monitored carefully, as its overconsumption compared to that of African palm oil could involve important alterations to hepatic metabolism.

  17. Hybrid particles and associated methods

    Science.gov (United States)

    Fox, Robert V; Rodriguez, Rene; Pak, Joshua J; Sun, Chivin

    2015-02-10

    Hybrid particles that comprise a coating surrounding a chalcopyrite material, the coating comprising a metal, a semiconductive material, or a polymer; a core comprising a chalcopyrite material and a shell comprising a functionalized chalcopyrite material, the shell enveloping the core; or a reaction product of a chalcopyrite material and at least one of a reagent, heat, and radiation. Methods of forming the hybrid particles are also disclosed.

  18. Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

    Science.gov (United States)

    Shu, Jessica Yo

    The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly

  19. HyDe: a Python Package for Genome-Scale Hybridization Detection.

    Science.gov (United States)

    Blischak, Paul D; Chifman, Julia; Wolfe, Andrea D; Kubatko, Laura S

    2018-03-19

    The analysis of hybridization and gene flow among closely related taxa is a common goal for researchers studying speciation and phylogeography. Many methods for hybridization detection use simple site pattern frequencies from observed genomic data and compare them to null models that predict an absence of gene flow. The theory underlying the detection of hybridization using these site pattern probabilities exploits the relationship between the coalescent process for gene trees within population trees and the process of mutation along the branches of the gene trees. For certain models, site patterns are predicted to occur in equal frequency (i.e., their difference is 0), producing a set of functions called phylogenetic invariants. In this paper we introduce HyDe, a software package for detecting hybridization using phylogenetic invariants arising under the coalescent model with hybridization. HyDe is written in Python, and can be used interactively or through the command line using pre-packaged scripts. We demonstrate the use of HyDe on simulated data, as well as on two empirical data sets from the literature. We focus in particular on identifying individual hybrids within population samples and on distinguishing between hybrid speciation and gene flow. HyDe is freely available as an open source Python package under the GNU GPL v3 on both GitHub (https://github.com/pblischak/HyDe) and the Python Package Index (PyPI: https://pypi.python.org/pypi/phyde).

  20. Study of Alkylthiolate Self-assembled Monolayers on Au(111) Using a Semilocal meta-GGA Density Functional

    DEFF Research Database (Denmark)

    Ferrighi, Lara; Pan, Yun-xiang; Grönbeck, Henrik

    2012-01-01

    We present a density functional theory study of the structure and stability of self-assembled monolayers (SAMs) of alkylthiolate on Au(111) as a function of the alkyl chain length. The most favorable structure of the SAMs involves an RS–Au–SR complex (S being sulfur, R being an alkyl chain) forme....... In particular, the use of M06-L yields an increased stability of the SAMs with increasing alkyl chain length and an increased attractive interaction between RS–Au–SR complexes at shorter distances....... through sandwiching one Au adatom by two alkylthiolates (RSs). Comparing a generalized gradient (GGA-PBE) and a meta-GGA (MGGA-M06-L) exchange-correlation functional we find that only the meta-GGA functional predicts the experimentally observed attractive intermolecular interactions within the SAMs...

  1. GalaxyDock BP2 score: a hybrid scoring function for accurate protein-ligand docking

    Science.gov (United States)

    Baek, Minkyung; Shin, Woong-Hee; Chung, Hwan Won; Seok, Chaok

    2017-07-01

    Protein-ligand docking is a useful tool for providing atomic-level understanding of protein functions in nature and design principles for artificial ligands or proteins with desired properties. The ability to identify the true binding pose of a ligand to a target protein among numerous possible candidate poses is an essential requirement for successful protein-ligand docking. Many previously developed docking scoring functions were trained to reproduce experimental binding affinities and were also used for scoring binding poses. However, in this study, we developed a new docking scoring function, called GalaxyDock BP2 Score, by directly training the scoring power of binding poses. This function is a hybrid of physics-based, empirical, and knowledge-based score terms that are balanced to strengthen the advantages of each component. The performance of the new scoring function exhibits significant improvement over existing scoring functions in decoy pose discrimination tests. In addition, when the score is used with the GalaxyDock2 protein-ligand docking program, it outperformed other state-of-the-art docking programs in docking tests on the Astex diverse set, the Cross2009 benchmark set, and the Astex non-native set. GalaxyDock BP2 Score and GalaxyDock2 with this score are freely available at http://galaxy.seoklab.org/softwares/galaxydock.html.

  2. Optimal energy management for a flywheel-based hybrid vehicle

    NARCIS (Netherlands)

    Berkel, van K.; Hofman, T.; Vroemen, B.G.; Steinbuch, M.

    2011-01-01

    This paper presents the modeling and design of an optimal Energy Management Strategy (EMS) for a flywheel-based hybrid vehicle, that does not use any electrical motor/generator, or a battery, for its hybrid functionalities. The hybrid drive train consists of only low-cost components, such as a

  3. Radiation protection during hybrid procedures: innovation creates new challenges.

    Science.gov (United States)

    Sawdy, Jaclynn M; Gocha, Mark D; Olshove, Vincent; Chisolm, Joanne L; Hill, Sharon L; Phillips, Alistair; Galantowicz, Mark; Cheatham, John P; Holzer, Ralf J

    2009-09-01

    The cooperation between interventional cardiologists and cardiothoracic surgeons has expanded the spectrum of treatment modalities for patients with congenital heart disease. These hybrid techniques have created new challenges, one of which being the provision of adequate but practical radiation protection. This study evaluates the use of a lightweight radiation protection drape (RADPAD) that may be suitable for shielding during hybrid procedures. To simulate a pediatric patient, an 8.7 liter water-filled tub was placed on an X-ray table and exposed to 10-second cine acquisition runs. Radiation exposure was measured at twelve specified locations around the table using a model with three different levels of radiation protection: no shielding, shielding using a traditional 0.35 mm lead-equivalent apron, and shielding using the 0.25 mm lead-equivalent RADPAD. The traditional lead apron and the RADPAD significantly reduced the amount of radiation dose when compared with no shielding. The standard lead apron provided slightly greater radiation protection than the RADPAD (0.000064 radiation absorbed dose [rad] vs. 0.000091 rad; p = 0.012). The measured rad was significantly higher on the right side of the table, and the measured radiation dose decreased significantly with increasing distance from the table. The RADPAD has been shown to function as an efficient shielding device, even though it does not quite match the protection that can be expected from a standard lead apron. It complies with regulatory radiation protection requirements and its lightweight and sterile use make it particularly useful during hybrid procedures in the operating room.

  4. Study of 4f hybridization in CeNiX with X=SnδGe1-δ, 0≤δ≤1

    International Nuclear Information System (INIS)

    Fuente, C. de la; Moral, A. del; Adroja, D.T.; Fraile, A.; Arnaudas, J.I.

    2010-01-01

    We report inelastic neutron scattering and core-level X-ray photoemission spectroscopy experiments for studying the Kondo problem in the CeNiX, X=Sn δ Ge 1-δ 0≤δ≤1 series. The neutron results confirm that they behave like a Kondo lattice for δ≥0.85, showing broad maxima at around 30 meV, typical of a crystal field magnetic scattering. So, the Ge doping could produce the suppression of the cerium magnetism observed for δ≤0.25. To open a more deep sight on this point, we have analyzed the 3d core-level XPS spectra by using the well-known Gunnarsson-Schoenhammer model. From this analysis, we have obtained the 'on-site' Coulomb bare repulsion for f states, U, and hybridization parameter, Δ, related with the hopping from the f states to the conduction ones. These U values are very similar for all compounds, about 7 eV, but the hybridization parameter slightly changes from 0.2 to 0.16 eV on increasing the Sn concentration. In Sn-rich compounds, the 4f occupation is close to spin limit fluctuation, which allows us to obtain an estimation of the Kondo temperatures, ∼1200 K, and the static 0 K susceptibility, ∼1.1x10 -3 emu/mol. Finally, we have done 'ab-initio' calculations based on the LDA+U+SO which confirm the existence of a small electronic gap opening in the DOS of Ge-rich compounds for U values lower than 7 eV.

  5. Overview, Progress, and Plans for the Compact Toroidal Hybrid Experiment

    Science.gov (United States)

    Hartwell, G. J.; Allen, N. R.; Ennis, D. A.; Hanson, J. D.; Howell, E. C.; Johnson, C. A.; Knowlton, S. F.; Kring, J. D.; Ma, X.; Maurer, D. A.; Ross, K. G.; Schmitt, J. C.; Traverso, P. J.; Williamson, E. N.

    2017-10-01

    The Compact Toroidal Hybrid (CTH) is an l = 2 , m = 5 torsatron/tokamak hybrid (R0 = 0.75 m, ap 0.2 m, and | B | disruption studies. The main goals of the CTH experiment are to study disruptive behavior as a function of applied 3D magnetic shaping, and to test and advance the V3FIT reconstruction code and NIMROD modeling of CTH. The disruptive density limit is observed to exceed the Greenwald limit as the vacuum transform is increased with no observed threshold for avoidance. Low-q operations (1.1 routine, with disruptions ceasing if the vacuum transform is raised above 0.07. Sawteeth are observed in CTH and have a similar phenomenology to tokamak sawteeth despite employing a 3D confining field. Application of vacuum transform has been demonstrated to reduce and eliminate the vertical drift of elongated discharges. Internal SXR diagnostics, in conjunction with external magnetics, extend the range of reconstruction accuracy into the plasma core. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.

  6. Hybrid soft computing approaches research and applications

    CERN Document Server

    Dutta, Paramartha; Chakraborty, Susanta

    2016-01-01

    The book provides a platform for dealing with the flaws and failings of the soft computing paradigm through different manifestations. The different chapters highlight the necessity of the hybrid soft computing methodology in general with emphasis on several application perspectives in particular. Typical examples include (a) Study of Economic Load Dispatch by Various Hybrid Optimization Techniques, (b) An Application of Color Magnetic Resonance Brain Image Segmentation by ParaOptiMUSIG activation Function, (c) Hybrid Rough-PSO Approach in Remote Sensing Imagery Analysis,  (d) A Study and Analysis of Hybrid Intelligent Techniques for Breast Cancer Detection using Breast Thermograms, and (e) Hybridization of 2D-3D Images for Human Face Recognition. The elaborate findings of the chapters enhance the exhibition of the hybrid soft computing paradigm in the field of intelligent computing.

  7. Density Functional Theory Simulations of Semiconductors for Photovoltaic Applications: Hybrid Organic-Inorganic Perovskites and III/V Heterostructures

    Directory of Open Access Journals (Sweden)

    Jacky Even

    2014-01-01

    Full Text Available Potentialities of density functional theory (DFT based methodologies are explored for photovoltaic materials through the modeling of the structural and optoelectronic properties of semiconductor hybrid organic-inorganic perovskites and GaAs/GaP heterostructures. They show how the properties of these bulk materials, as well as atomistic relaxations, interfaces, and electronic band-lineups in small heterostructures, can be thoroughly investigated. Some limitations of available standard DFT codes are discussed. Recent improvements able to treat many-body effects or based on density-functional perturbation theory are also reviewed in the context of issues relevant to photovoltaic technologies.

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

    KAUST Repository

    Kö rzdö rfer, Thomas; Bredas, Jean-Luc

    2014-01-01

    -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

  9. Generalised Computability and Applications to Hybrid Systems

    DEFF Research Database (Denmark)

    Korovina, Margarita V.; Kudinov, Oleg V.

    2001-01-01

    We investigate the concept of generalised computability of operators and functionals defined on the set of continuous functions, firstly introduced in [9]. By working in the reals, with equality and without equality, we study properties of generalised computable operators and functionals. Also we...... propose an interesting application to formalisation of hybrid systems. We obtain some class of hybrid systems, which trajectories are computable in the sense of computable analysis. This research was supported in part by the RFBR (grants N 99-01-00485, N 00-01- 00810) and by the Siberian Branch of RAS (a...... grant for young researchers, 2000)...

  10. Evolution and molecular control of hybrid incompatibility in plants

    Directory of Open Access Journals (Sweden)

    Chen Chen

    2016-08-01

    Full Text Available Postzygotic reproductive isolation (RI plays an important role in speciation. According to the stage at which it functions and the symptoms it displays, postzygotic RI can be called hybrid inviability, hybrid weakness or necrosis, hybrid sterility, or hybrid breakdown. In this review, we summarized new findings about hybrid incompatibilities in plants, most of which are from studies on Arabidopsis and rice. Recent progress suggests that hybrid incompatibility is a by-product of co-evolution either with parasitic selfish elements in the genome or with invasive microbes in the natural environment. We discuss the environmental influences on the expression of hybrid incompatibility and the possible effects of environment-dependent hybrid incompatibility on sympatric speciation. We also discuss the role of domestication on the evolution of hybrid incompatibilities.

  11. Hybrid broadband Ground Motion simulation based on a dynamic rupture model of the 2011 Mw 9.0 Tohoku earthquake.

    Science.gov (United States)

    Galvez, P.; Somerville, P.; Bayless, J.; Dalguer, L. A.

    2015-12-01

    The rupture process of the 2011 Tohoku earthquake exhibits depth-dependent variations in the frequency content of seismic radiation from the plate interface. This depth-varying rupture property has also been observed in other subduction zones (Lay et al, 2012). During the Tohoku earthquake, the shallow region radiated coherent low frequency seismic waves whereas the deeper region radiated high frequency waves. Several kinematic inversions (Suzuki et al, 2011; Lee et al, 2011; Bletery et al, 2014; Minson et al, 2014) detected seismic waves below 0.1 Hz coming from the shallow depths that produced slip larger than 40-50 meters close to the trench. Using empirical green functions, Asano & Iwata (2012), Kurahashi and Irikura (2011) and others detected regions of strong ground motion radiation at frequencies up to 10Hz located mainly at the bottom of the plate interface. A recent dynamic model that embodies this depth-dependent radiation using physical models has been developed by Galvez et al (2014, 2015). In this model the rupture process is modeled using a linear weakening friction law with slip reactivation on the shallow region of the plate interface (Galvez et al, 2015). This model reproduces the multiple seismic wave fronts recorded on the Kik-net seismic network along the Japanese coast up to 0.1 Hz as well as the GPS displacements. In the deep region, the rupture sequence is consistent with the sequence of the strong ground motion generation areas (SMGAs) that radiate high frequency ground motion at the bottom of the plate interface (Kurahashi and Irikura, 2013). It remains challenging to perform ground motions fully coupled with a dynamic rupture up to 10 Hz for a megathrust event. Therefore, to generate high frequency ground motions, we make use of the stochastic approach of Graves and Pitarka (2010) but add to the source spectrum the slip rate function of the dynamic model. In this hybrid-dynamic approach, the slip rate function is windowed with Gaussian

  12. Compton profiles and Mulliken’s populations of cobalt, nickel and copper tungstates: Experiment and theory

    Energy Technology Data Exchange (ETDEWEB)

    Meena, B.S. [Department of Physics, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Heda, N.L. [Department of Pure and Applied Physics, University of Kota, Kota 324010, Rajasthan (India); Kumar, Kishor; Bhatt, Samir; Mund, H.S. [Department of Physics, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India)

    2016-03-01

    We present the first ever studies on Compton profiles of AWO{sub 4} (A=Co, Ni and Cu) using 661.65 keV γ-rays emitted by {sup 137}Cs source. The experimental momentum densities have been employed to validate exchange and correlation potentials within linear combination of atomic orbitals (LCAO) method. Density functional theory (DFT) with local density approximation and generalized gradient approximation and also the hybridization of Hartree-Fock and DFT (B3LYP and PBE0) have been considered under LCAO scheme. The LCAO-B3LYP scheme is found to be in better agreement with the experimental data than other approximations considered in this work, suggesting applicability of B3LYP approach in predicting the electronic properties of these tungstates. The Mulliken’s population (MP) data show charge transfer from Co/Ni/Cu and W to O atoms. The experimental profiles when normalized to same area show almost similar localization of 3d electrons (in real space) of Ni and Cu which is lower than that of Co in their AWO{sub 4} environment.

  13. Electronic response of rare-earth magnetic-refrigeration compounds GdX2 (X = Fe and Co)

    Science.gov (United States)

    Bhatt, Samir; Ahuja, Ushma; Kumar, Kishor; Heda, N. L.

    2018-05-01

    We present the Compton profiles (CPs) of rare-earth-transition metal compounds GdX2 (X = Fe and Co) using 740 GBq 137Cs Compton spectrometer. To compare the experimental momentum densities, we have also computed the CPs, electronic band structure, density of states (DOS) and Mulliken population (MP) using linear combination of atomic orbitals (LCAO) method. Local density and generalized gradient approximations within density functional theory (DFT) along with the hybridization of Hartree-Fock and DFT (B3LYP and PBE0) have been considered under the framework of LCAO scheme. It is seen that the LCAO-B3LYP based momentum densities give a better agreement with the experimental data for both the compounds. The energy bands and DOS for both the spin-up and spin-down states show metallic like character of the reported intermetallic compounds. The localization of 3d electrons of Co and Fe has also been discussed in terms of equally normalized CPs and MP data. Discussion on magnetization using LCAO method is also included.

  14. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Science.gov (United States)

    Ambrosio, Francesco; Miceli, Giacomo; Pasquarello, Alfredo

    2015-12-01

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H+/H2 level defining the standard hydrogen electrode, the OH-/OH∗ level corresponding to the oxidation of the hydroxyl ion, and the H2O/OH∗ level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band-edge positions, and redox levels in overall

  15. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Francesco, E-mail: Francesco.Ambrosio@epfl.ch; Miceli, Giacomo; Pasquarello, Alfredo [Chaire de Simulation à l’Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2015-12-28

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H{sup +}/H{sub 2} level defining the standard hydrogen electrode, the OH{sup −}/OH{sup ∗} level corresponding to the oxidation of the hydroxyl ion, and the H{sub 2}O/OH{sup ∗} level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band

  16. Structure functions in the decay τ±→π±π0π0ντ

    International Nuclear Information System (INIS)

    Browder, T. E.; Li, Y.; Rodriguez, J. L.; Yamamoto, H.; Bergfeld, T.; Eisenstein, B. I.; Ernst, J.; Gladding, G. E.; Gollin, G. D.; Hans, R. M.

    2000-01-01

    Using the CLEO II detector operating at the Cornell Electron Storage Ring (CESR) e + e - collider, we have measured the structure functions in the decay τ ± →π ± π 0 π 0 ν τ , based on a sample corresponding to 4x10 6 produced τ-pair events. We determine the integrated structure functions, which depend only on the three pion invariant mass, as well as the structure functions differential in the Dalitz plot variables. We extract model independent limits on non-axial-vector contributions from the measured structure functions as less than 16.6% of the total branching fraction, at the 95% confidence level. Separating the non-axial-vector contributions into scalar and vector contributions, we measure that scalars (vectors) contribute with less than 9.4% (7.3%) to the total branching fraction, at the 95% confidence level. (c) 2000 The American Physical Society

  17. Preparation and characterization of trihydroxamic acid functionalized carbon materials for the removal of Cu(II) ions from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Godino-Salido, M. Luz, E-mail: mlgodino@ujaen.es [Departamento de Química Inorgánica y Orgánica, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071, Jaén (Spain); Santiago-Medina, Antonio; López-Garzón, Rafael; Gutiérrez-Valero, María D.; Arranz-Mascarós, Paloma; López de la Torre, M. Dolores [Departamento de Química Inorgánica y Orgánica, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071, Jaén (Spain); Domingo-García, María; López-Garzón, F. Javier [Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, 18071, Granada (Spain)

    2016-11-30

    Highlights: • Hybrid materials made by irreversible adsorption of a deferoxamine derivative on ACs. • The surface trihydroxamate groups are the active functions of the hybrid materials. • Great adsorption capacity for Cu(II) of novel trihydroxamic acid functionalized ACs. • Desorption of Cu(II) from the loaded hybrid materials regenerates the parent hybrids. - Abstract: The main objective of this study is to prepare and characterize two functionalizated carbon materials with enhanced adsorptive properties for Cu(II). Thus, two novel hybrid materials have been prepared by a non-covalent functionalization method based on the adsorption of a pyrimidine-desferrioxamine-B conjugate compound (H{sub 4}L) on two activated carbons, ACs (labelled Merck and F). The adsorption of H{sub 4}L on the ACs is pH-dependent and highly irreversible. This is due to strong π-π interactions between the arene centers of the ACs and the pyrimidine moiety of H{sub 4}L. The textural characterization of the AC/H{sub 4}L hybrids shows large decreases of their surface areas. Thus the values of Merck and F are 1031 and 1426 m{sup 2}/g respectively, while these of Merck/H{sub 4}L and F/H{sub 4}L hybrids are 200 and 322 m{sup 2}/g. An important decrease in the micropore volumes is also found, due to the blockage of narrow porosity produced by the adsorption of H{sub 4}L molecules. The ACs/H{sub 4}L hybrids show larger adsorption capacities for Cu(II) (0.105(4) and 0.13(2) mmol/g, at pH 2.0, and 0.20(3) and 0.242(9) mmol/g, at pH 5.5, for Merck/H{sub 4}L and F/H{sub 4}L, respectively) than those of the ACs (0.024(6) and 0.096(9) mmol/g, at pH 2.0, and 0.10(2) and 0.177(8) mmol/g, at pH 5.5, for Merck and F respectively), which is explained on the basis of the complexing ability of the trihydroxamic acid functions. The desorption of Cu(II) from the ACs/H{sub 4}L/Cu(II) materials in acid solution allows the regeneration of most active sites (78.5% in the case of Merck/H{sub 4}L/Cu(II) and 83.0

  18. Nacre-like hybrid films: Structure, properties, and the effect of relative humidity.

    Science.gov (United States)

    Abba, Mohammed T; Hunger, Philipp M; Kalidindi, Surya R; Wegst, Ulrike G K

    2015-03-01

    Functional materials often are hybrids composed of biopolymers and mineral constituents. The arrangement and interactions of the constituents frequently lead to hierarchical structures with exceptional mechanical properties and multifunctionality. In this study, hybrid thin films with a nacre-like brick-and-mortar microstructure were fabricated in a straightforward and reproducible manner through manual shear casting using the biopolymer chitosan as the matrix material (mortar) and alumina platelets as the reinforcing particles (bricks). The ratio of inorganic to organic content was varied from 0% to 15% and the relative humidities from 36% to 75% to determine their effects on the mechanical properties. It was found that increasing the volume fraction of alumina from 0% to 15% results in a twofold increase in the modulus of the film, but decreases the tensile strength by up to 30%, when the volume fraction of alumina is higher than 5%. Additionally, this study quantifies and illustrates the critical role of the relative humidity on the mechanical properties of the hybrid film. Increasing the relative humidity from 36% to 75% decreases the modulus and strength by about 45% and triples the strain at failure. These results suggest that complex hybrid materials can be manufactured and tailor made for specific applications or environmental conditions. Copyright © 2015. Published by Elsevier Ltd.

  19. Diffusion of interstitial oxygen in silicon and germanium: a hybrid functional study

    International Nuclear Information System (INIS)

    Colleoni, Davide; Pasquarello, Alfredo

    2016-01-01

    The minimum-energy paths for the diffusion of an interstitial O atom in silicon and germanium are studied through the nudged-elastic-band method and hybrid functional calculations. The reconsideration of the diffusion of O in silicon primarily serves the purpose of validating the procedure for studying the O diffusion in germanium. Our calculations show that the minimum energy path goes through an asymmetric transition state in both silicon and germanium. The stability of these transition states is found to be enhanced by the generation of unpaired electrons in the highest occupied single-particle states. Calculated energy barriers are 2.54 and 2.14 eV for Si and Ge, in very good agreement with corresponding experimental values of 2.53 and 2.08 eV, respectively. (paper)

  20. Hybrid colloidal plasmonic-photonic crystals.

    Science.gov (United States)

    Romanov, Sergei G; Korovin, Alexander V; Regensburger, Alois; Peschel, Ulf

    2011-06-17

    We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Synergistic effect of cellulose nanocrystals/graphene oxide nanosheets as functional hybrid nanofiller for enhancing properties of PVA nanocomposites.

    Science.gov (United States)

    El Miri, Nassima; El Achaby, Mounir; Fihri, Aziz; Larzek, Mohamed; Zahouily, Mohamed; Abdelouahdi, Karima; Barakat, Abdellatif; Solhy, Abderrahim

    2016-02-10

    Novel functional hybrid nanofillers composed of cellulose nanocrystals (CNC) and graphene oxide nanosheets (GON), at different weight ratios (2:1, 1:1 and 1:2), were successfully prepared and characterized, and their synergistic effect in enhancing the properties of poly(vinyl alcohol) (PVA) nanocomposites was investigated. Due to the synergistic reinforcement, it was found that the Young's modulus, tensile strength and toughness of the PVA nanocomposite containing 5 wt% hybrid nanofiller (1:2) were significantly improved by 320%, 124% and 159%, respectively; and the elongation at break basically remained compared to the neat PVA matrix. In addition, the glass and melting temperatures as well as the moisture sorption of nanocomposites were also enhanced. This synergistic effect improved the dispersion homogeneity by avoiding the agglomeration phenomenon of nanofillers within the polymer matrix, resulting in nanocomposites with largely enhanced properties compared to those prepared from single nanofiller (CNC or GON). The preparation of these hybrid nanofillers and their incorporation into a polymer provided a novel method for the development of novel multifunctional nanocomposites based on the combination of existing nanomaterials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Diaphite, a new type of surface with mixed sp{sup 2}-sp{sup 3} hybridization for adsorption and functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Radosinski, Lukasz, E-mail: lukasz.radosinski@pwr.edu.pl [Wroclaw University of Science and Technology, Chemistry Department, Group of Bioprocess and Biomedical Engineering, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Formalik, Filip [Wroclaw University of Science and Technology, Chemistry Department, Group of Bioprocess and Biomedical Engineering, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Olejniczak, Adam [Department of Spectroscopy of Excited States, Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okolna 2, 50-422 Wroclaw (Poland); Radosz, Andrzej [Wroclaw University of Science and Technology, Faculty of Fundamental Problems of Technology, Department of Quantum Technologies, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2017-05-15

    Highlights: • Recent discoveries show a possibility of photoinduced formation of a structure of mixed sp{sub 2}-sp{sub 3} hybridization out of graphite and graphene–diaphite. • Ab initio and molecular mechanics calculations indicate that the surface exhibits large enhancement of binding energy due to favorable sp{sub 3} like hybridization. • The binding energy varies upon configuration of occupied adsorption sites and the adsorption sites form a regular bed-like matrix. - Abstract: We theoretically study a new carbon phase with mixed sp{sup 2}-sp{sup 3} bond hybridization called diaphite. Using ab initio calculations and the adaptive intermolecular reactive bond order (AIREBO) potential approach, we show that the surface of this structure exhibits enhanced adsorption capabilities. Specifically, using hydrogen as a test adsorbate, we calculate that the chemical binding energy, depending on the configuration of hydrogen atoms, varies from 2.08 to 2.9 eV. Furthermore, the adsorption sites form a regular matrix; thus, we postulate that this new stable carbon phase may be a universal matrix for functionalization.

  3. The Minimum Data Set 3.0 Cognitive Function Scale.

    Science.gov (United States)

    Thomas, Kali S; Dosa, David; Wysocki, Andrea; Mor, Vincent

    2017-09-01

    The Minimum Data Set (MDS) 3.0 introduced the Brief Interview for Mental Status (BIMS), a short performance-based cognitive screener for nursing home (NH) residents. Not all residents are able to complete the BIMS and are consequently assessed by staff. We designed a Cognitive Function Scale (CFS) integrating self-report and staff-report data and present evidence of the scale's construct validity. A retrospective cohort study. The subjects consisted of 3 cohorts: (1) long-stay NH residents (N=941,077) and (2) new admissions (N=2,066,580) during 2011-2012, and (3) residents with the older MDS 2.0 assessment in 2010 and the newer MDS 3.0 assessment (n=688,511). MDS 3.0 items were used to create a single, integrated 4-category hierarchical CFS that was compared with residents' prior MDS 2.0 Cognitive Performance Scale scores and other concurrent MDS 3.0 measures of construct validity. The new CFS suggests that 28% of the long-stay cohort in 2011-2012 were cognitively intact, 22% were mildly impaired, 33% were moderately impaired, and 17% were severely impaired. For the admission cohort, the CFS noted 56% as cognitively intact, 23% as mildly impaired, 17% as moderately impaired, and 4% as severely impaired. The CFS corresponded closely with residents' prior MDS 2.0 Cognitive Performance Scale scores and with performance of Activities of Daily Living, and nurses' judgments of function and behavior in both the admission and long-stay cohorts. The new CFS is valuable to researchers as it provides a single, integrated measure of NH residents' cognitive function, regardless of the mode of assessment.

  4. Preparation and Physicochemical Properties of Functionalized Silica/Octamethacryl-Silsesquioxane Hybrid Systems

    Directory of Open Access Journals (Sweden)

    Karolina Szwarc-Rzepka

    2013-01-01

    Full Text Available Alkoxysilane-grafted silica/polyhedral oligomeric silsesquioxane with methacryl substituents (SiO2/silane/POSS hybrid material was synthesized according to hydrolyzation and condensation reactions in the so-called “bifunctionalization process.” It is a new attractive system because of its physicochemical, especially thermal and structural, properties. This innovative method of preparation as well as specific physicochemical and useful properties determine the potential applications of such products in many industries. The structure and physicochemical parameters of obtained hybrid systems were characterized using infrared spectroscopy (FTIR, 13C and 29Si solid-state nuclear magnetic resonance (CP MAS NMR, and thermal analysis. The mechanism of bifunctionalization reaction was proposed. The chemical immobilization of silane coupling agent and Methacryl POSS onto silica support surface was noted during the study. Those changes caused a significant increase in the hydrophobic character of fillers obtained. Moreover, changes in thermal stability of SiO2/silane/POSS hybrid systems in comparison to pure POSS modifier were also observed.

  5. The angular dependence of spin-state energy splittings in the ? core

    Science.gov (United States)

    Groß, Lynn; Steenbock, Torben; Herrmann, Carmen

    2013-07-01

    Spin-state energy splittings are highly relevant for catalysis, molecular magnetism, and materials science, yet continue to pose a challenge for electronic structure methods. For a Fe2O2+ 2 core, we evaluate the bridging angle dependence of energy splittings between ferromagnetically and antiferromagnetically coupled states for different exchange-correlation functionals, and compare with complete active space self-consistent field (CASSCF) values, also including second-order perturbative corrections (CASPT2). CASSCF and CASPT2 yield strong antiferromagnetic coupling, with the smallest coupling at 100°, and a smooth dependence on the angle for Fe-O-Fe angles of 70° to 120°. Interestingly, this is qualitatively the same behaviour as often found for stable dinuclear transition metal complexes. While all functionals show the same angular dependence as CASPT2, they favour the antiferromagnetic state less strongly. Pure functionals such as BP86, BLYP, SSB-D, and TPSS come closer to the CASPT2 results (with energy splittings by about 60 kJ/mol smaller than the CASPT2 ones) than hybrid functionals. The hybrid functionals B3LYP, B3LYP⋆, and PBE0 favour the antiferromagnetic state even less strongly, resulting in ferromagnetic coupling for angles around 100°. The good qualitative agreement between CASPT2 and CASSCF on the one hand and CASPT2 and density functional theory on the other hand for angles between 70° and 110° suggests that the chosen active space of 18 electrons in 14 orbitals may be adequate for spin-state energy splitting of Fe2O2+ 2 in that region (possibly due to error cancellation), while angles of 60° or 120° may require larger active spaces. This study is complemented by an analysis of local spins, local charges, and CASSCF natural orbitals.

  6. Feedback error learning controller for functional electrical stimulation assistance in a hybrid robotic system for reaching rehabilitation

    Directory of Open Access Journals (Sweden)

    Francisco Resquín

    2016-07-01

    Full Text Available Hybrid robotic systems represent a novel research field, where functional electrical stimulation (FES is combined with a robotic device for rehabilitation of motor impairment. Under this approach, the design of robust FES controllers still remains an open challenge. In this work, we aimed at developing a learning FES controller to assist in the performance of reaching movements in a simple hybrid robotic system setting. We implemented a Feedback Error Learning (FEL control strategy consisting of a feedback PID controller and a feedforward controller based on a neural network. A passive exoskeleton complemented the FES controller by compensating the effects of gravity. We carried out experiments with healthy subjects to validate the performance of the system. Results show that the FEL control strategy is able to adjust the FES intensity to track the desired trajectory accurately without the need of a previous mathematical model.

  7. Biodistribution and Pharmacokinetics Study of siRNA-loaded Anti-NTSR1-mAb-functionalized Novel Hybrid Nanoparticles in a Metastatic Orthotopic Murine Lung Cancer Model

    Directory of Open Access Journals (Sweden)

    Maryna Perepelyuk

    2016-01-01

    Full Text Available Small interfering RNA (siRNA is effective in silencing critical molecular pathways in cancer. The use of this tool as a treatment modality is limited by lack of an intelligent carrier system to enhance the preferential delivery of this molecule to specific targets in vivo. In the present study, the in vivo behavior of novel anti-NTSR1-mAb-functionalized antimutant K-ras siRNA-loaded hybrid nanoparticles, delivered by i.p. injection to non-small-cell lung cancer in mice models, was investigated and compared to that of a naked siRNA formulation. The siRNA in anti-NTSR1-mAb-functionalized hybrid nanoparticles was preferentially accumulated in tumor-bearing lungs and metastasized tumor for at least 48 hours while the naked siRNA formulation showed lack of preferential accumulation in all of the organs monitored. The plasma terminal half-life of nanoparticle-delivered siRNA was 11 times higher (17–1.5 hours than that of the naked siRNA formulation. The mean residence time and AUClast were 3.4 and 33 times higher than the corresponding naked siRNA formulation, respectively. High-performance liquid chromatography analysis showed that the hybrid nanoparticle carrier system protected the encapsulated siRNA against degradation in vivo. Our novel anti-NTSR1-mAb-functionalized hybrid nanoparticles provide a useful platform for in vivo targeting of siRNA for both experimental and clinical purposes.

  8. XRD analysis of strained Ge-SiGe heterostructures on relaxed SiGe graded buffers grown by hybrid epitaxy on Si(0 0 1) substrates

    International Nuclear Information System (INIS)

    Franco, N.; Barradas, N.P.; Alves, E.; Vallera, A.M.; Morris, R.J.H.; Mironov, O.A.; Parker, E.H.C.

    2005-01-01

    Ge/Si 1-x Ge x inverted modulation doped heterostructures with Ge channel thickness of 16 and 20 nm were grown by a method of hybrid epitaxy followed by ex situ annealing at 650 deg. C for p-HMOS application. The thicker layers of the virtual substrate (6000 nm graded SiGe up to x = 0.6 and 1000 nm uniform composition with x = 0.6) were produced by ultrahigh vacuum chemical vapor deposition (UHV-CVD) while the thinner, Si(2 nm)-SiGe(20 nm)-Ge-SiGe(15 nm + 5 nm B-doped + 20 nm) active layers were grown by low temperature solid-source (LT-SS) MBE at T = 350 deg. C. As-grown and annealed samples were measured by X-ray diffraction (XRD). Reciprocal space maps (RSMs) allowed us to determine non-destructively the precise composition (∼1%) and strain of the Ge channel, along with similar information regarding the other layers that made up the whole structure. Layer thickness was determined with complementary high-resolution Rutherford backscattering (RBS) experiments

  9. Improved functionality of graphene and carbon nanotube hybrid foam architecture by UV-ozone treatment

    Science.gov (United States)

    Wang, Wei; Ruiz, Isaac; Lee, Ilkeun; Zaera, Francisco; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2015-04-01

    Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability.Optimization of the electrode/electrolyte double-layer interface is a key factor for improving electrode performance of aqueous electrolyte based supercapacitors (SCs). Here, we report the improved functionality of carbon materials via a non-invasive, high-throughput, and inexpensive UV generated ozone (UV-ozone) treatment. This process allows precise tuning of the graphene and carbon nanotube hybrid foam (GM) transitionally from ultrahydrophobic to hydrophilic within 60 s. The continuous tuning of surface energy can be controlled by simply varying the UV-ozone exposure time, while the ozone-oxidized carbon nanostructure maintains its integrity. Symmetric SCs based on the UV-ozone treated GM foam demonstrated enhanced rate performance. This technique can be readily applied to other CVD-grown carbonaceous materials by taking advantage of its ease of processing, low cost, scalability, and controllability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr06795a

  10. Glueballs, hybrids, multiquarks

    Energy Technology Data Exchange (ETDEWEB)

    Klempt, Eberhard [Helmholtz-Institut fuer Strahlen-und Kernphysik der Rheinischen Friedrich-Wilhelms Universitaet, Nussallee 14-16, D-53115 Bonn (Germany)], E-mail: klempt@hiskp.uni-bonn.de; Zaitsev, Alexander [Institute for High-Energy Physics, Moscow Region, RU-142284 Protvino (Russian Federation)

    2007-12-15

    Glueballs, hybrids and multiquark states are predicted as bound states in models guided by quantum chromo dynamics (QCD), by QCD sum rules or QCD on a lattice. Estimates for the (scalar) glueball ground state are in the mass range from 1000 to 1800 MeV, followed by a tensor and a pseudoscalar glueball at higher mass. Experiments have reported evidence for an abundance of meson resonances with 0{sup -+},0{sup ++} and 2{sup ++} quantum numbers. In particular, the sector of scalar mesons is full of surprises starting from the elusive {sigma} and {kappa} mesons. The a{sub 0}(980) and f{sub 0}(980), discussed extensively in the literature, are reviewed with emphasis on their Janus-like appearance as KK-bar molecules, tetraquark states or qq-bar mesons. Most exciting is the possibility that the three mesons f{sub 0}(1370), f{sub 0}(1500), and f{sub 0}(1710) might reflect the appearance of a scalar glueball in the world of quarkonia. However, the existence of f{sub 0}(1370) is not beyond doubt and there is evidence that both f{sub 0}(1500) and f{sub 0}(1710) are flavour octet states, possibly in a tetraquark composition. We suggest a scheme in which the scalar glueball is dissolved into the wide background into which all scalar flavour-singlet mesons collapse. There is an abundance of meson resonances with the quantum numbers of the {eta}. Three states are reported below 1.5GeV/c{sup 2} whereas quark models expect only one, perhaps two. One of these states, {iota}(1440), was the prime glueball candidate for a long time. We show that {iota}(1440) is the first radial excitation of the {eta} meson. Hybrids may have exotic quantum numbers which are not accessible by qq-bar mesons. There are several claims for J{sup PC}=1{sup -+} exotics, some of them with properties as predicted from the flux tube model interpreting the quark-antiquark binding by a gluon string. The evidence for these states depends partly on the assumption that meson-meson interactions are dominated by s

  11. Numerical solution to generalized Burgers'-Fisher equation using Exp-function method hybridized with heuristic computation.

    Science.gov (United States)

    Malik, Suheel Abdullah; Qureshi, Ijaz Mansoor; Amir, Muhammad; Malik, Aqdas Naveed; Haq, Ihsanul

    2015-01-01

    In this paper, a new heuristic scheme for the approximate solution of the generalized Burgers'-Fisher equation is proposed. The scheme is based on the hybridization of Exp-function method with nature inspired algorithm. The given nonlinear partial differential equation (NPDE) through substitution is converted into a nonlinear ordinary differential equation (NODE). The travelling wave solution is approximated by the Exp-function method with unknown parameters. The unknown parameters are estimated by transforming the NODE into an equivalent global error minimization problem by using a fitness function. The popular genetic algorithm (GA) is used to solve the minimization problem, and to achieve the unknown parameters. The proposed scheme is successfully implemented to solve the generalized Burgers'-Fisher equation. The comparison of numerical results with the exact solutions, and the solutions obtained using some traditional methods, including adomian decomposition method (ADM), homotopy perturbation method (HPM), and optimal homotopy asymptotic method (OHAM), show that the suggested scheme is fairly accurate and viable for solving such problems.

  12. Numerical solution to generalized Burgers'-Fisher equation using Exp-function method hybridized with heuristic computation.

    Directory of Open Access Journals (Sweden)

    Suheel Abdullah Malik

    Full Text Available In this paper, a new heuristic scheme for the approximate solution of the generalized Burgers'-Fisher equation is proposed. The scheme is based on the hybridization of Exp-function method with nature inspired algorithm. The given nonlinear partial differential equation (NPDE through substitution is converted into a nonlinear ordinary differential equation (NODE. The travelling wave solution is approximated by the Exp-function method with unknown parameters. The unknown parameters are estimated by transforming the NODE into an equivalent global error minimization problem by using a fitness function. The popular genetic algorithm (GA is used to solve the minimization problem, and to achieve the unknown parameters. The proposed scheme is successfully implemented to solve the generalized Burgers'-Fisher equation. The comparison of numerical results with the exact solutions, and the solutions obtained using some traditional methods, including adomian decomposition method (ADM, homotopy perturbation method (HPM, and optimal homotopy asymptotic method (OHAM, show that the suggested scheme is fairly accurate and viable for solving such problems.

  13. Elasticity-based development of functionally enhanced multicellular 3D liver encapsulated in hybrid hydrogel.

    Science.gov (United States)

    Lee, Ho-Joon; Son, Myung Jin; Ahn, Jiwon; Oh, Soo Jin; Lee, Mihee; Kim, Ansoon; Jeung, Yun-Ji; Kim, Han-Gyeul; Won, Misun; Lim, Jung Hwa; Kim, Nam-Soon; Jung, Cho-Rock; Chung, Kyung-Sook

    2017-12-01

    Current in vitro liver models provide three-dimensional (3-D) microenvironments in combination with tissue engineering technology and can perform more accurate in vivo mimicry than two-dimensional models. However, a human cell-based, functionally mature liver model is still desired, which would provide an alternative to animal experiments and resolve low-prediction issues on species differences. Here, we prepared hybrid hydrogels of varying elasticity and compared them with a normal liver, to develop a more mature liver model that preserves liver properties in vitro. We encapsulated HepaRG cells, either alone or with supporting cells, in a biodegradable hybrid hydrogel. The elastic modulus of the 3D liver dynamically changed during culture due to the combined effects of prolonged degradation of hydrogel and extracellular matrix formation provided by the supporting cells. As a result, when the elastic modulus of the 3D liver model converges close to that of the in vivo liver (≅ 2.3 to 5.9 kPa), both phenotypic and functional maturation of the 3D liver were realized, while hepatic gene expression, albumin secretion, cytochrome p450-3A4 activity, and drug metabolism were enhanced. Finally, the 3D liver model was expanded to applications with embryonic stem cell-derived hepatocytes and primary human hepatocytes, and it supported prolonged hepatocyte survival and functionality in long-term culture. Our model represents critical progress in developing a biomimetic liver system to simulate liver tissue remodeling, and provides a versatile platform in drug development and disease modeling, ranging from physiology to pathology. We provide a functionally improved 3D liver model that recapitulates in vivo liver stiffness. We have experimentally addressed the issues of orchestrated effects of mechanical compliance, controlled matrix formation by stromal cells in conjunction with hepatic differentiation, and functional maturation of hepatocytes in a dynamic 3D

  14. (0 0 1) Facet-exposed anatase-phase TiO{sub 2} nanotube hybrid reduced graphene oxide composite: Synthesis, characterization and application in photocatalytic degradation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xun [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Shi, Tiejun, E-mail: stjhfut@163.com [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Wu, Jing [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); Zhou, Haiou [School of Chemical Engineering of Hefei University of Technology, Hefei 230009 (China); School of Materials and Chemical Engineering of Anhui University of Architecture, Hefei 230901 (China)

    2013-12-15

    Reduced graphene oxide (RGO) and TiO{sub 2} nanotube (TNT) with (0 0 1) facet-exposed anatase phase are covalently bonded together to synthesize TNT hybrid RGO (RGO-TNT) through consecutive process such as hydrothermal reaction, HCl washing, lyophilization and heat treatment with graphene oxide (GO), TiO{sub 2} powder and high concentration NaOH solution as the starting materials. The TNT with the diameter between 10 and 20 nm characterized by high resolution transmission electron microscopy (HRTEM) is in anatase phase proven by X-ray diffraction (XRD) and HRTEM. Additionally, the more active (0 0 1) facet is exposed identified by HRTEM. More significantly, TNT is bridged to RGO by C-Ti bond by the measurement of X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) spectra has testified that RGO in RGO-TNT can transfer and accept photoelectrons from TNT. The photocatalytic activity of RGO-TNT for degrading methylene blue (MB) is enhanced by contrast with pure TNT, and changeable by adjusting the mass ratios of GO to TiO{sub 2} powder. Simultaneously, lyophilization is benefit for maintaining the high active surface area of RGO-TNT, which is deeply in relationship with a higher photocatalytic activity. After four running cycles of photocatalytic degradation, RGO-TNT has shown a high stability and perfect reproducibility.

  15. Effect of sample storage time on detection of hybridization signals in Checkerboard DNA-DNA hybridization.

    Science.gov (United States)

    do Nascimento, Cássio; Muller, Katia; Sato, Sandra; Albuquerque Junior, Rubens Ferreira

    2012-04-01

    Long-term sample storage can affect the intensity of the hybridization signals provided by molecular diagnostic methods that use chemiluminescent detection. The aim of this study was to evaluate the effect of different storage times on the hybridization signals of 13 bacterial species detected by the Checkerboard DNA-DNA hybridization method using whole-genomic DNA probes. Ninety-six subgingival biofilm samples were collected from 36 healthy subjects, and the intensity of hybridization signals was evaluated at 4 different time periods: (1) immediately after collecting (n = 24) and (2) after storage at -20 °C for 6 months (n = 24), (3) for 12 months (n = 24), and (4) for 24 months (n = 24). The intensity of hybridization signals obtained from groups 1 and 2 were significantly higher than in the other groups (p  0.05). The Checkerboard DNA-DNA hybridization method was suitable to detect hybridization signals from all groups evaluated, and the intensity of signals decreased significantly after long periods of sample storage.

  16. Design and Biological Evaluation of Antifouling Dihydrostilbene Oxime Hybrids.

    Science.gov (United States)

    Moodie, Lindon W K; Cervin, Gunnar; Trepos, Rozenn; Labriere, Christophe; Hellio, Claire; Pavia, Henrik; Svenson, Johan

    2018-04-01

    By combining the recently reported repelling natural dihydrostilbene scaffold with an oxime moiety found in many marine antifoulants, a library of nine antifouling hybrid compounds was developed and biologically evaluated. The prepared compounds were shown to display a low antifouling effect against marine bacteria but a high potency against the attachment and growth of microalgae down to MIC values of 0.01 μg/mL for the most potent hybrid. The mode of action can be characterized as repelling via a reversible non-toxic biostatic mechanism. Barnacle cyprid larval settlement was also inhibited at low μg/mL concentrations with low levels or no toxicity observed. Several of the prepared compounds performed better than many reported antifouling marine natural products. While several of the prepared compounds are highly active as antifoulants, no apparent synergy is observed by incorporating the oxime functionality into the dihydrostilbene scaffold. This observation is discussed in light of recently reported literature data on related marine natural antifoulants and antifouling hybrids as a potentially general strategy for generation of improved antifoulants.

  17. 47 CFR 0.51 - Functions of the Bureau.

    Science.gov (United States)

    2010-10-01

    ... promote the vital interests of the American public in international commerce, national defense, and... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL COMMISSION ORGANIZATION Organization International Bureau § 0.51 Functions of the Bureau. The International Bureau has the following duties and...

  18. Performances Study of a Hybrid Rocket Engine

    Directory of Open Access Journals (Sweden)

    Adrian-Nicolae BUTURACHE

    2018-06-01

    Full Text Available This paper presents a study which analyses the functioning and performances optimization of a hybrid rocket engine based on gaseous oxygen and polybutadiene polymer (HTPB. Calculations were performed with NASA CEA software in order to obtain the parameters resulted following the combustion process. Using these parameters, the main parameters of the hybrid rocket engine were optimized. Using the calculus previously stated, an experimental rocket engine producing 100 N of thrust was pre-dimensioned, followed by an optimization of the rocket engine as a function of several parameters. Having the geometry and the main parameters of the hybrid rocket engine combustion process, numerical simulations were performed in the CFX – ANSYS commercial software, which allowed visualizing the flow field and the jet expansion. Finally, the analytical calculus was validated through numerical simulations.

  19. Synthesis of boronate-functionalized organic-inorganic hybrid monolithic column for the separation of cis-diol containing compounds at low pH.

    Science.gov (United States)

    Zhao, Heqing; Lyu, Haixia; Qin, Wenfei; Xie, Zenghong

    2018-04-01

    In this work, an organic-inorganic hybrid boronate affinity monolithic column was prepared via "one-pot" process using 4-vinylphenylboronic acid as organic monomer and divinylbenzene as cross-linker. The effects of reaction temperature, solvents and composition of organic monomers on the column properties (e.g. morphology, permeability, and mechanical stability) were investigated. A series of test compounds including small neutral molecules, aromatic amines, and cis-diol compounds were used to evaluate the retention behaviors of the prepared hybrid monolithic column. The results demonstrated that the prepared hybrid monolith exhibited mixed-interactions including hydrophilicity, cation exchange, and boronate affinity interaction. The run-to-run, day-to-day and batch-to-batch reproducibilities of the prepared hybrid monolith for thiourea's retention time were satisfactory with the relative standard deviations (RSDs) less than 0.09, 1.45 and 4.05% (n = 3), respectively, indicating the effectiveness and practicability of the proposed method. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Electronic structure of the amorphous oxide semiconductor a-InGaZnO4-x: Tauc-Lorentz optical model and origins of subgap states

    International Nuclear Information System (INIS)

    Kamiya, Toshio; Nomura, Kenji; Hosono, Hideo

    2009-01-01

    This paper discusses an optical model and subgap electronic states for a representative amorphous oxide semiconductor, InGaZnO 4 (a-IGZO). Parameterized optical models were developed based on the Tauc-Lorentz model combined with a Lorentz-type oscillator. The measured optical absorption spectra exhibit nearly linear dependences on photon energy (E) between 3 eV 0,TL ) being around 4 eV. The optimized parameters for the fixed E 0,TL of 3.7 eV are provided for four different a-IGZO films with root-mean-square errors less than 1%. Formation energies of crystalline IGZO, stoichiometric a-IGZO, oxygen deficient a-IGZO and their constituent oxides were calculated by the density functional theory using the local density approximation (LDA) and generalized gradient approximation with PBE96 functionals (PBE). PBE gives larger unit cell volumes at the ground states and better agreement in the formation energies than LDA does. The formation energies of an oxygen deficiency in a-IGZO were calculated to be 3.2-3.5 eV. The calculated electronic structures of stoichiometric a-IGZO models exhibit somewhat large dispersions for conduction bands (CB), which are not largely affected by the disordered structure in a-IGZO, while the dispersions of the valence bands (VBs) are very small, unlike the crystalline IGZO, showing that a-IGZO have strongly localized states at the VB maximums (VBMs). Oxygen-deficient a-IGZO models showed that oxygen deficiencies form both a deep localized state at 0.4-1 eV above VBM and a shallow donor state depending on local atomic configurations. An oxygen deficiency that forms a deep state breaks the dispersion of the CB, which could be an origin of the subgap states observed near CB. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Theoretical study of the microscopic appearance of the capture and storage of CO2 by zeolites: Studies of Zn-imidazole and triazole clusters with CO2

    International Nuclear Information System (INIS)

    Boulmene, Rida

    2016-01-01

    Several experimental and theoretical studies have shown the ability of zeolitic-imidazole frameworks (ZIFs) materials to capture the CO 2 gas. In this study, we have focused on the interaction of CO 2 with one of the sub-unit of ZIFs i.e. the complex between the imidazole and zinc (Im-Zn+q, q = 0,1, 2) or triazole without zinc. Various adsorption sites are examined for these complexes.The calculations were performed using ab initio methods MP2; CCSD(T)-F12 and density functional theory with PBE PBE0, M1 and M05-2X functionals with different basis set (aug-cc-pVDZ, aug-cc-pVTZ and 6-311++G(d, p), tightly integrated in GAUSSIAN and MOLPRO packages. The Grimme corrections for dispersion forces description (DFT-D3) are also included. Our results shows that the stability of our complex structures is achieved by the presence of strong covalent bonds (chemical bonds of organic ligands) and also by Van der Waals and hydrogen weak bonds. Both types of bonding are in competition. This allowed us to better understand the experimental observations. (author)

  2. Cooperative Control for A Hybrid Rehabilitation System Combining Functional Electrical Stimulation and Robotic Exoskeleton

    Directory of Open Access Journals (Sweden)

    Dingguo Zhang

    2017-12-01

    Full Text Available Functional electrical stimulation (FES and robotic exoskeletons are two important technologies widely used for physical rehabilitation of paraplegic patients. We developed a hybrid rehabilitation system (FEXO Knee that combined FES and an exoskeleton for swinging movement control of human knee joints. This study proposed a novel cooperative control strategy, which could realize arbitrary distribution of torque generated by FES and exoskeleton, and guarantee harmonic movements. The cooperative control adopted feedfoward control for FES and feedback control for exoskeleton. A parameter regulator was designed to update key parameters in real time to coordinate FES controller and exoskeleton controller. Two muscle groups (quadriceps and hamstrings were stimulated to generate active torque for knee joint in synchronization with torque compensation from exoskeleton. The knee joint angle and the interactive torque between exoskeleton and shank were used as feedback signals for the control system. Central pattern generator (CPG was adopted that acted as a phase predictor to deal with phase confliction of motor patterns, and realized synchronization between the two different bodies (shank and exoskeleton. Experimental evaluation of the hybrid FES-exoskeleton system was conducted on five healthy subjects and four paraplegic patients. Experimental results and statistical analysis showed good control performance of the cooperative control on torque distribution, trajectory tracking, and phase synchronization.

  3. Mesenchymal stem cells generate distinct functional hybrids in vitro via cell fusion or entosis.

    Science.gov (United States)

    Sottile, Francesco; Aulicino, Francesco; Theka, Ilda; Cosma, Maria Pia

    2016-11-09

    Homotypic and heterotypic cell-to-cell fusion are key processes during development and tissue regeneration. Nevertheless, aberrant cell fusion can contribute to tumour initiation and metastasis. Additionally, a form of cell-in-cell structure called entosis has been observed in several human tumours. Here we investigate cell-to-cell interaction between mouse mesenchymal stem cells (MSCs) and embryonic stem cells (ESCs). MSCs represent an important source of adult stem cells since they have great potential for regenerative medicine, even though they are also involved in cancer progression. We report that MSCs can either fuse forming heterokaryons, or be invaded by ESCs through entosis. While entosis-derived hybrids never share their genomes and induce degradation of the target cell, fusion-derived hybrids can convert into synkaryons. Importantly we show that hetero-to-synkaryon transition occurs through cell division and not by nuclear membrane fusion. Additionally, we also observe that the ROCK-actin/myosin pathway is required for both fusion and entosis in ESCs but only for entosis in MSCs. Overall, we show that MSCs can undergo fusion or entosis in culture by generating distinct functional cellular entities. These two processes are profoundly different and their outcomes should be considered given the beneficial or possible detrimental effects of MSC-based therapeutic applications.

  4. Cooperative Control for A Hybrid Rehabilitation System Combining Functional Electrical Stimulation and Robotic Exoskeleton.

    Science.gov (United States)

    Zhang, Dingguo; Ren, Yong; Gui, Kai; Jia, Jie; Xu, Wendong

    2017-01-01

    Functional electrical stimulation (FES) and robotic exoskeletons are two important technologies widely used for physical rehabilitation of paraplegic patients. We developed a hybrid rehabilitation system (FEXO Knee) that combined FES and an exoskeleton for swinging movement control of human knee joints. This study proposed a novel cooperative control strategy, which could realize arbitrary distribution of torque generated by FES and exoskeleton, and guarantee harmonic movements. The cooperative control adopted feedfoward control for FES and feedback control for exoskeleton. A parameter regulator was designed to update key parameters in real time to coordinate FES controller and exoskeleton controller. Two muscle groups (quadriceps and hamstrings) were stimulated to generate active torque for knee joint in synchronization with torque compensation from exoskeleton. The knee joint angle and the interactive torque between exoskeleton and shank were used as feedback signals for the control system. Central pattern generator (CPG) was adopted that acted as a phase predictor to deal with phase confliction of motor patterns, and realized synchronization between the two different bodies (shank and exoskeleton). Experimental evaluation of the hybrid FES-exoskeleton system was conducted on five healthy subjects and four paraplegic patients. Experimental results and statistical analysis showed good control performance of the cooperative control on torque distribution, trajectory tracking, and phase synchronization.

  5. Hybrid density functional theory study of Cu(In1−xGaxSe2 band structure for solar cell application

    Directory of Open Access Journals (Sweden)

    Xu-Dong Chen

    2014-08-01

    Full Text Available Cu(In1−xGaxSe2 (CIGS alloy based thin film photovoltaic solar cells have attracted more and more attention due to its large optical absorption coefficient, long term stability, low cost and high efficiency. However, the previous theoretical investigation of this material with first principle calculation cannot fulfill the requirement of experimental development, especially the accurate description of band structure and density of states. In this work, we use first principle calculation based on hybrid density functional theory to investigate the feature of CIGS, with B3LYP applied in the CuIn1−xGaxSe2 stimulation of the band structure and density of states. We report the simulation of the lattice parameter, band gap and chemical composition. The band gaps of CuGaSe2, CuIn0.25Ga0.75Se2, CuIn0.5Ga0.5Se2, CuIn0.75Ga0.25Se2 and CuInSe2 are obtained as 1.568 eV, 1.445 eV, 1.416 eV, 1.275 eV and 1.205 eV according to our calculation, which agree well with the available experimental values. The band structure of CIGS is also in accordance with the current theory.

  6. Item-level informant discrepancies across obese-overweight children and their parents on the PedsQL™ 4.0 instrument: an iterative hybrid ordinal logistic regression.

    Science.gov (United States)

    Jafari, Peyman; Allahyari, Elahe; Salarzadeh, Mina; Bagheri, Zahra

    2016-01-01

    Child obesity has become a major health concern worldwide. In order to provide successful intervention strategies, it is necessary to understand how obese-overweight children and their parents perceive obesity and its consequences on child's health-related quality of life (HRQoL). This study aimed to assess measurement equivalence of the PedsQL™ 4.0 across obese-overweight children and their parents. The items in the PedsQL™ 4.0 were analysed for differential item functioning (DIF) across obese-overweight children and their parents using an iterative hybrid ordinal logistic regression/item response theory approach. The sample included 647 overweight-obese children and their parents, who completed child and parent reports of the PedsQL™ 4.0, respectively. Overall, 17 out of 23 (74%) items were flagged with DIF across two groups: eight items exhibited uniform DIF and nine items non-uniform DIF. In addition, parents of obese children rated the child's HRQoL significantly lower than their children in all domains of the PedsQL™ 4.0, and this finding did not change whether or not items with uniform DIF were included. Although obese-overweight children and their parents interpret items of the PedsQL™ 4.0 in a conceptually different manner, removing or retaining DIF items in the subscales had no significant effects on group differences. Accordingly, it appears that observed differences in HRQoL scores across child and parent reports are a true difference and not a reflection of measurement artefact.

  7. CPHmodels-3.0--remote homology modeling using structure-guided sequence profiles

    DEFF Research Database (Denmark)

    Nielsen, Morten; Lundegaard, Claus; Lund, Ole

    2010-01-01

    CPHmodels-3.0 is a web server predicting protein 3D structure by use of single template homology modeling. The server employs a hybrid of the scoring functions of CPHmodels-2.0 and a novel remote homology-modeling algorithm. A query sequence is first attempted modeled using the fast CPHmodels-2.......0 profile-profile scoring function suitable for close homology modeling. The new computational costly remote homology-modeling algorithm is only engaged provided that no suitable PDB template is identified in the initial search. CPHmodels-3.0 was benchmarked in the CASP8 competition and produced models.......3 A. These performance values place the CPHmodels-3.0 method in the group of high performing 3D prediction tools. Beside its accuracy, one of the important features of the method is its speed. For most queries, the response time of the server is...

  8. Exact exchange and Wilson-Levy correlation: a pragmatic device for studying complex weakly-bonded systems.

    Science.gov (United States)

    Walsh, T R

    2005-02-07

    The Wilson-Levy (WL) correlation functional is used together with Hartree-Fock (HF) theory to evaluate interaction energies at intermediate separations (i.e. around equilibrium separation) for several weakly-bonded systems. The HF+WL approach reproduces binding trends for all complexes studied: selected rare-gas dimers, isomers of the methane dimer, benzene dimer and naphthalene dimer, and base-pair stacking structures for pyrimidine, cytosine, uracil and guanine dimers. These HF+WL data are contrasted against results obtained from some popular functionals (including B3LYP and PBE), as well as two newly-developed functionals, X3LYP and xPBE. The utility of HF+WL, with reference to exact-exchange (EXX) density-functional theory, is discussed in terms of a suggested EXXWL exchange-correlation functional.

  9. Accurate Energies and Structures for Large Water Clusters Using the X3LYP Hybrid Density Functional

    OpenAIRE

    Su, Julius T.; Xu, Xin; Goddard, William A., III

    2004-01-01

    We predict structures and energies of water clusters containing up to 19 waters with X3LYP, an extended hybrid density functional designed to describe noncovalently bound systems as accurately as covalent systems. Our work establishes X3LYP as the most practical ab initio method today for calculating accurate water cluster structures and energies. We compare X3LYP/aug-cc-pVTZ energies to the most accurate theoretical values available (n = 2−6, 8), MP2 with basis set superposition error (BSSE)...

  10. The effect of concentration ratio and type of functional group on synthesis of CNT-ZnO hybrid nanomaterial by an in situ sol-gel process

    Science.gov (United States)

    Hosseini Largani, Sekineh; Akbarzadeh Pasha, Mohammad

    2017-12-01

    In this research, MWCNT-ZnO hybrid nanomaterials were synthesized by a simple sol-gel process using Zn(CH3COO)2·2H2O and functionalized MWCNT with carboxyl(COOH) and hydroxyl(OH) groups. Three different mass ratios of MWCNT:ZnO = 3:1, 1:1 and 1:3 were examined. The prepared nanomaterials were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR). Successful growth of MWCNT-ZnO hybrids for both COOH and OH functional groups and all the three mass ratios were obtained. The ZnO nanoparticles attached on the surfaces of CNTs have rather spherical shapes and hexagonal crystal structure. By increasing the concentration of ZnO, the number and average size of ZnO nanoparticles decorated the body of CNTs in hybrid structures increase. By increasing the ZnO precursor, the distribution of ZnO nanoparticles that appeared on the surface of CNTs becomes more uniform. The SEM observation beside EDX analysis revealed that at the same concentration ratio the amount of ZnO loading on the surface of MWCNT-COOH is more than MWCNT-OH. Moreover, the average size of ZnO nanoparticles attached on the surface of COOH functionalized CNTs is relatively smaller than that of OH functionalized ones.

  11. A comprehensive study of g-factors, elastic, structural and electronic properties of III-V semiconductors using hybrid-density functional theory

    Science.gov (United States)

    Bastos, Carlos M. O.; Sabino, Fernando P.; Sipahi, Guilherme M.; Da Silva, Juarez L. F.

    2018-02-01

    Despite the large number of theoretical III-V semiconductor studies reported every year, our atomistic understanding is still limited. The limitations of the theoretical approaches to yield accurate structural and electronic properties on an equal footing, is due to the unphysical self-interaction problem that mainly affects the band gap and spin-orbit splitting (SOC) in semiconductors and, in particular, III-V systems with similar magnitude of the band gap and SOC. In this work, we report a consistent study of the structural and electronic properties of the III-V semiconductors by using the screening hybrid-density functional theory framework, by fitting the α parameters for 12 different III-V compounds, namely, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, and InSb, to minimize the deviation between the theoretical and experimental values of the band gap and SOC. Structural relaxation effects were also included. Except for AlP, whose α = 0.127, we obtained α values that ranged from 0.209 to 0.343, which deviate by less than 0.1 from the universal value of 0.25. Our results for the lattice parameter and elastic constants indicate that the fitting of α does not affect those structural parameters when compared with the HSE06 functional, where α = 0.25. Our analysis of the band structure based on the k ṡ p method shows that the effective masses are in agreement with the experimental values, which can be attributed to the simultaneous fitting of the band gap and SOC. Also, we estimate the values of g-factors, extracted directly from the band structure, which are close to experimental results, which indicate that the obtained band structure produced a realistic set of k ṡ p parameters.

  12. Peritonite bacteriana espontânea na cirrose hepática: prevalência, fatores preditivos e prognóstico Spontaneous bacterial peritonitis in hepatic cirrhosis: prevalence, predictive factors and prognosis

    Directory of Open Access Journals (Sweden)

    F.A.F. Figueiredo

    1999-04-01

    Full Text Available OBJETIVO: Investigar prevalência, fatores preditivos e prognóstico dos episódios de Peritonite Bacteriana Espontânea (PBE na cirrose hepática. METODOLOGIA: Estudamos, prospectivamente, 143 pacientes com cirrose hepática, ambulatoriais ou internados, que foram atendidos nos Serviços de Clínica Médica do HUCFF e de Gastroenterologia do HUPE no período de janeiro/95 a janeiro/96. Estes pacientes foram submetidos a questionário, exame físico, colheita de sangue e paracentese abdominal com colheita de líquido ascítico (LA e, então, acompanhados por um período médio de 4 meses, onde a taxa de mortalidade foi determinada. RESULTADOS: A prevalência de PBE foi cerca de 20%, sendo 24% PBE cultura positiva, 66% Ascite Neutrofílica cultura negativa e 10% Bacterioascite. Na análise univariada, alcançaram significância estatística (p=0.05 como fatores preditivos do episódio de PBE: HGI na semana anterior; passado de encefalopatia hepática; classificação de Child; dosagens séricas de proteínas, albumina, C3, C4 e uréia; dosagens no LA de C3 e C4. Após serem introduzidas na análise multivariada, apenas HGI na semana anterior, albumina sérica e C4 do LA foram independentemente correlacionadas ao episódio de PBE (p=0.05. A mortalidade hospitalar e durante o acompanhento foi de 33,3% e 53,8% para o grupo com PBE; 8,5% e 31,9% para o grupo sem PBE; respectivamente (p=0.01 e p=0.04. A probabilidade cumulativa de sobrevida foi significativamente menor no grupo com PBE. CONCLUSÕES: A PBE é uma complicação freqüente, depende, principalmente, da gravidade da doença hepática e é um marcador de prognóstico desfavorável nos pacientes com cirrose hepática.BACKGROUND: Spontaneous Bacterial Peritonitis (SBP is a common and potentially fatal complication of cirrhosis. Multiple variants of this infection have been described during the past decade. Few studies have investigated SBP in Brazil. MATERIAL AND METHOD: In order to

  13. Estimates of hybridization between two species of catostomids in the Columbia River

    Energy Technology Data Exchange (ETDEWEB)

    Dauble, D.D.; Buschbom, R.L.

    1981-01-01

    Extent of hybridization is described between two sympatric catostomids, Catostomus macrocheilus and C. columbianus, from the Hanford Reach of the Columbia River, southeastern Washington state. Estimated percentage of hybrids based on presence of intermediate meristic characters ranged from 12.4 to 14.6% of the total sucker population. Discriminant function analysis reduced subjective variability and lowered estimates of hybridization to 3.0 to 7.1%. Principal component analysis also provided evidence that the suspected hybrids were intermediate between populations of C. macrocheilus and C. columbianus. Meristic characters contributed most to all methods of treatment, with number of lateral line scales the best single criterion for species separation. Any analysis of closely related species would benefit from examination of offspring from artificial crosses and from knowledge of allopatric population characteristics. Breakdown of isolating mechanisms leading to C. macrocheilus X C. columbianus crosses may result from overlap in spawning time and incomplete habitat segregation. Morphological and coloration differences at spawning may provide a basis for species recognition, thus providing some degree of ethological isolation.

  14. Noncovalent functionalization of pristine CVD single-walled carbon nanotubes with 3d metal(II) phthalocyanines by adsorption from the gas phase

    Science.gov (United States)

    Basiuk, Vladimir A.; Flores-Sánchez, Laura J.; Meza-Laguna, Victor; Flores-Flores, José Ocotlán; Bucio-Galindo, Lauro; Puente-Lee, Iván; Basiuk, Elena V.

    2018-04-01

    Noncovalent hybrids of carbon nanotubes (CNTs) with phthalocyanines (Pcs) is a subject of growing research effort focused on the development of new efficient organic photovoltaic cells, heterogeneous catalysts, lithium batteries, gas sensors, field effect transistors, among other possible applications. The main advantage of using unsubstituted Pcs is their very moderate cost and easy commercial availability. Unfortunately, the deposition of unsubstituted Pcs onto CNT sidewalls via the traditional liquid-phase strategy proves to be very problematic due to an extremely poor solubility of Pcs. At the same time, unsubstituted free-base H2Pc ligand and many of its transition metal complexes exhibit high thermal stability and volatility under reduced pressure, which allows for their physical vapor deposition onto solid surfaces. In the present work, we demonstrated the possibility of simple, fast, efficient and environmentally friendly noncovalent functionalization of single-walled CNTs (SWNTs) with a series of 3d metal(II) phthalocyanines Me(II)Pc, where Me = Co, Ni, Cu and Zn. The functionalization can be performed at 400-500 °C under moderate vacuum, and takes about 2-3 h only. The nanohybrids obtained were characterized by means of Fourier-transform infrared, Raman, UV-vis and energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), scanning and transmission electron microscopy. TGA suggested that Pc weight content is 30%, 17% and 35% for NiPc, CuPc and ZnPc, respectively (CoPc exhibited anomalous behavior), which is close to the estimates from EDS spectra of 24-39%, 27-36% and 27-44% for CoPc, CuPc and ZnPc, respectively. A strong increase in intensity of D band in the Raman spectra of SWNT‒Pc hybrids, as compared to that of pristine nanotubes, was interpreted as very strong interactions between Pc molecules and SWNT sidewalls. Very high absolute values of binding energies of 32.46-37.12 kcal/mol and the patterns of HOMO and LUMO distribution

  15. Stability analysis of hybrid-driven underwater glider

    Science.gov (United States)

    Niu, Wen-dong; Wang, Shu-xin; Wang, Yan-hui; Song, Yang; Zhu, Ya-qiang

    2017-10-01

    Hybrid-driven underwater glider is a new type of unmanned underwater vehicle, which combines the advantages of autonomous underwater vehicles and traditional underwater gliders. The autonomous underwater vehicles have good maneuverability and can travel with a high speed, while the traditional underwater gliders are highlighted by low power consumption, long voyage, long endurance and good stealth characteristics. The hybrid-driven underwater gliders can realize variable motion profiles by their own buoyancy-driven and propeller propulsion systems. Stability of the mechanical system determines the performance of the system. In this paper, the Petrel-II hybrid-driven underwater glider developed by Tianjin University is selected as the research object and the stability of hybrid-driven underwater glider unitedly controlled by buoyancy and propeller has been targeted and evidenced. The dimensionless equations of the hybrid-driven underwater glider are obtained when the propeller is working. Then, the steady speed and steady glide path angle under steady-state motion have also been achieved. The steady-state operating conditions can be calculated when the hybrid-driven underwater glider reaches the desired steady-state motion. And the steadystate operating conditions are relatively conservative at the lower bound of the velocity range compared with the range of the velocity derived from the method of the composite Lyapunov function. By calculating the hydrodynamic coefficients of the Petrel-II hybrid-driven underwater glider, the simulation analysis has been conducted. In addition, the results of the field trials conducted in the South China Sea and the Danjiangkou Reservoir of China have been presented to illustrate the validity of the analysis and simulation, and to show the feasibility of the method of the composite Lyapunov function which verifies the stability of the Petrel-II hybrid-driven underwater glider.

  16. A hybrid mammalian cell cycle model

    Directory of Open Access Journals (Sweden)

    Vincent Noël

    2013-08-01

    Full Text Available Hybrid modeling provides an effective solution to cope with multiple time scales dynamics in systems biology. Among the applications of this method, one of the most important is the cell cycle regulation. The machinery of the cell cycle, leading to cell division and proliferation, combines slow growth, spatio-temporal re-organisation of the cell, and rapid changes of regulatory proteins concentrations induced by post-translational modifications. The advancement through the cell cycle comprises a well defined sequence of stages, separated by checkpoint transitions. The combination of continuous and discrete changes justifies hybrid modelling approaches to cell cycle dynamics. We present a piecewise-smooth version of a mammalian cell cycle model, obtained by hybridization from a smooth biochemical model. The approximate hybridization scheme, leading to simplified reaction rates and binary event location functions, is based on learning from a training set of trajectories of the smooth model. We discuss several learning strategies for the parameters of the hybrid model.

  17. Algorithm for locating the extremum of a multi-dimensional constrained function and its application to the PPPL Hybrid Study

    International Nuclear Information System (INIS)

    Bathke, C.

    1978-03-01

    A description is presented of a general algorithm for locating the extremum of a multi-dimensional constrained function. The algorithm employs a series of techniques dominated by random shrinkage, steepest descent, and adaptive creeping. A discussion follows of the algorithm's application to a ''real world'' problem, namely the optimization of the price of electricity, P/sub eh/, from a hybrid fusion-fission reactor. Upon the basis of comparisons with other optimization schemes of a survey nature, the algorithm is concluded to yield a good approximation to the location of a function's optimum

  18. Description of the Charge Transfer States at the Pentacene/C60 Interface: Combining Range-Separated Hybrid Functionals with the Polarizable Continuum Model

    KAUST Repository

    Zheng, Zilong; Bredas, Jean-Luc; Coropceanu, Veaceslav

    2016-01-01

    are usually performed on small-size donor/acceptor complexes and as result do not account for electronic polarization effects. Here, using a pentacene/C60 complex as a model system, we discuss the ability of long-range corrected (LCR) hybrid functionals

  19. Correction: General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory.

    Science.gov (United States)

    Roch, Loïc M; Baldridge, Kim K

    2018-02-07

    Correction for 'General optimization procedure towards the design of a new family of minimal parameter spin-component-scaled double-hybrid density functional theory' by Loïc M. Roch and Kim K. Baldridge, Phys. Chem. Chem. Phys., 2017, 19, 26191-26200.

  20. A hybrid choice model with nonlinear utility functions and bounded distributions for latent variables : application to purchase intention decisions of electric cars

    NARCIS (Netherlands)

    Kim, J.; Rasouli, S.; Timmermans, H.J.P.

    2014-01-01

    The hybrid choice model (HCM) provides a powerful framework to account for heterogeneity across decision-makers in terms of different underlying latent attitudes. Typically, effects of the latent attitudes have been represented assuming linear utility functions. In contributing to the further