WorldWideScience

Sample records for bond functionalization approach

  1. Atom and Bond Fukui Functions and Matrices: A Hirshfeld-I Atoms-in-Molecule Approach.

    Science.gov (United States)

    Oña, Ofelia B; De Clercq, Olivier; Alcoba, Diego R; Torre, Alicia; Lain, Luis; Van Neck, Dimitri; Bultinck, Patrick

    2016-09-19

    The Fukui function is often used in its atom-condensed form by isolating it from the molecular Fukui function using a chosen weight function for the atom in the molecule. Recently, Fukui functions and matrices for both atoms and bonds separately were introduced for semiempirical and ab initio levels of theory using Hückel and Mulliken atoms-in-molecule models. In this work, a double partitioning method of the Fukui matrix is proposed within the Hirshfeld-I atoms-in-molecule framework. Diagonalizing the resulting atomic and bond matrices gives eigenvalues and eigenvectors (Fukui orbitals) describing the reactivity of atoms and bonds. The Fukui function is the diagonal element of the Fukui matrix and may be resolved in atom and bond contributions. The extra information contained in the atom and bond resolution of the Fukui matrices and functions is highlighted. The effect of the choice of weight function arising from the Hirshfeld-I approach to obtain atom- and bond-condensed Fukui functions is studied. A comparison of the results with those generated by using the Mulliken atoms-in-molecule approach shows low correlation between the two partitioning schemes.

  2. Assessment of recently developed density functional approaches for the evaluation of the bond length alternation in polyacetylene

    Science.gov (United States)

    Jacquemin, Denis; Perpète, Eric. A.; Ciofini, Ilaria; Adamo, Carlo

    2005-04-01

    The bond length alternation (BLA) of increasingly long polyacetylene oligomers has been computed using various wavefunction methods of increasing accuracy and several DFT models, including standard GGA and the most-recent meta-GGA and hybrid functionals. Our results show the meta-GGA functionals do not offer any significant improvement with respect to the GGA approaches, both providing too small values for the BLA. More accurate results are obtained with hybrid approaches, where, instead, the percent of HF exchange rules the quantitative result. In particular, hybrids including 25% of HF exchange are the most accurate, whereas TPSSh, O3LYP, τ-HCTHh provide only poor estimates.

  3. Study on the covalence of Cu and chemical bonding in an inorganic fullerene-like molecule, [CuCl]20[Cp*FeP5]12[Cu-(CH3CN)2+Cl-]5, by a density functional approach

    Institute of Scientific and Technical Information of China (English)

    WANG Bingwu; XU Guangxian; CHEN Zhida

    2004-01-01

    The electronic structure and chemical bonding in a recently synthesized inorganic fullerene-like molecule, {[CuCl]20[Cp*FeP5]12 [Cu(CH3CN)+2Cl-]5}, has been studied by a density functional approach. Geometrical optimization of the three basic structural units of the molecule is performed with Amsterdam Density Functional Program. The results are in agreement with the experiment. Localized MO's obtained by Boys-Foster method give a clear picture of the chemical bonding in this molecule. The reason why CuCl can react with Cp*FeP5 in solvent CH3CN to form the fullerene-like molecule is explained in terms of the soft-hard Lewis acid base theory and a new concept of covalence.

  4. Density functional study of the bonding in small silicon clusters

    International Nuclear Information System (INIS)

    We report the ground electronic state, equilibrium geometry, vibrational frequencies, and binding energy for various isomers of Sin(n = 2--8) obtained with the linear combination of atomic orbitals-density functional method. We used both a local density approximation approach and one with gradient corrections. Our local density approximation results concerning the relative stability of electronic states and isomers are in agreement with Hartree--Fock and Moller--Plesset (MP2) calculations [K. Raghavachari and C. M. Rohlfing, J. Chem. Phys. 89, 2219 (1988)]. The binding energies calculated with the gradient corrected functional are in good agreement with experiment (Si2 and Si3) and with the best theoretical estimates. Our analysis of the bonding reveals two limiting modes of bonding and classes of silicon clusters. One class of clusters is characterized by relatively large s atomic populations and a large number of weak bonds, while the other class of clusters is characterized by relatively small s atomic populations and a small number of strong bonds

  5. A GENERAL APPROACH TO VALUING COMMODITY-LINKED BONDS

    OpenAIRE

    Jin, Yufei; Turvey, Calum G.

    2004-01-01

    The purpose of this paper is to develop a general approach to valuing commodity-linked bonds (CLBs) based on the Heath-Jarrow-Morton (HJM) framework. The model deals with four dimensions of uncertainty: prices of the underlying commodity, the value of firm that issues bonds, interest rates, and convenience yields. A mathematical formula for the price of a commodity-linked bond is derived. The previous results in Black and Scholes (1973), Merton (1973), Schwartz (1982), and Atta-Mensah (1992) ...

  6. Automating Partial Period Bond Valuation with Excel's Day Counting Functions

    Science.gov (United States)

    Vicknair, David; Spruell, James

    2009-01-01

    An Excel model for calculating the actual price of bonds under a 30 day/month, 360 day/year day counting assumption by nesting the DAYS360 function within the PV function is developed. When programmed into an Excel spreadsheet, the model can accommodate annual and semiannual payment bonds sold on or between interest dates using six fundamental…

  7. Mean bond-length variation in crystal structures: a bond-valence approach.

    Science.gov (United States)

    Bosi, Ferdinando

    2014-08-01

    The distortion theorem of the bond-valence theory predicts that the mean bond length 〈D〉 increases with increasing deviation of the individual bond lengths from their mean value according to the equation 〈D〉 = (D' + ΔD), where D' is the length found in a polyhedron having equivalent bonds and ΔD is the bond distortion. For a given atom, D' is expected to be similar from one structure to another, whereas 〈D〉 should vary as a function of ΔD. However, in several crystal structures 〈D〉 significantly varies without any relevant contribution from ΔD. In accordance with bond-valence theory, 〈D〉 variation is described here by a new equation: 〈D〉 = (DRU + ΔDtop + ΔDiso + ΔDaniso + ΔDelec), where DRU is a constant related to the type of cation and coordination environment, ΔDtop is the topological distortion related to the way the atoms are linked, ΔDiso is an isotropic effect of compression (or stretching) in the bonds produced by steric strain and represents the same increase (or decrease) in all the bond lengths in the coordination sphere, ΔDaniso is the distortion produced by compression and stretching of bonds in the same coordination sphere, ΔDelec is the distortion produced by electronic effects. If present, ΔDelec can be combined with ΔDaniso because they lead to the same kind of distortions in line with the distortion theorem. Each D-index, in the new equation, corresponds to an algebraic expression containing experimental and theoretical bond valences. On the basis of this study, the ΔD index defined in bond valence theory is a result of both the bond topology and the distortion theorem (ΔD = ΔDtop + ΔDaniso + ΔDelec), and D' is a result of the compression, or stretching, of bonds (D' = DRU + ΔDiso). The deficiencies present in the bond-valence theory in explaining mean bond-length variations can therefore be overcome, and the observed variations of 〈D〉 in crystal structures can be

  8. Free-Radical Triggered Ordered Domino Reaction: An Approach to C-C Bond Formation via Selective Functionalization of α-Hydroxyl-(sp(3))C-H in Fluorinated Alcohols.

    Science.gov (United States)

    Xu, Zhengbao; Hang, Zhaojia; Liu, Zhong-Quan

    2016-09-16

    A free-radical mediated highly ordered radical addition/cyclization/(sp(3))C-C(sp(3)) formation domino reaction is developed. Three new C-C bonds are formed one by one in a mixed system. Furthermore, it represents the first example of cascade C-C bond formation via selective functionalization of α-hydroxyl-C(sp(3))-H in fluorinated alcohols.

  9. Evaluating Callable and Putable Bonds: An Eigenfunction Expansion Approach

    OpenAIRE

    Dongjae Lim; Lingfei Li; Vadim Linetsky

    2012-01-01

    We propose an efficient method to evaluate callable and putable bonds under a wide class of interest rate models, including the popular short rate diffusion models, as well as their time changed versions with jumps. The method is based on the eigenfunction expansion of the pricing operator. Given the set of call and put dates, the callable and putable bond pricing function is the value function of a stochastic game with stopping times. Under some technical conditions, it is shown to have an e...

  10. Universal bond correlation function for two-dimensional polymer rings

    OpenAIRE

    Sakaue, Takahiro; Witz, Guillaume; Dietler, Giovanni; Wada, Hirofumi

    2010-01-01

    The bond orientational correlation function (BCF) of a semiflexible ring polymer on a flat surface is studied theoretically. For a stiff chain, we give an exact analytic form of BCF with perturbation calculations. For a chain sufficiently longer than its persistence length, the conventional exponential decay vanishes and a long-range order along the chain contour appears. We demonstrate that the bond orientational correlation satisfies the scaling properties, and construct an interpolating fo...

  11. Effect of water storage on resin-dentin bond strengths formed by different bonding approaches

    Directory of Open Access Journals (Sweden)

    Martins G

    2009-01-01

    Full Text Available Objectives: The purpose of this study was to evaluate the influence of water storage on resin-dentin bond strengths [µTBS] using different adhesive bonding approaches. Materials and Methods: Flat superficial dentin surfaces of 24 extracted human third molars were exposed and polished to create a standardized smear layer. The teeth were randomly distributed into four different groups: Three-step etch-and-rinse (Adper Scotchbond Multi-Purpose, 3M ESPE - SBMP, two-step etch-and-rinse (Adper Single Bond 2, 3 M ESPE - SB; two-step self-etch (AdheSE, Ivoclar/Vivadent - AD; and self-etch 1 step (Adper Prompt L-Pop, 3M ESPE - LP. Following the adhesive application (n = 6, resin composite was incrementally applied (Filtek™ Supreme XT - 3 M ESPE in order to obtain bonded sticks, with a cross-sectioned area of 0.81 mm 2 . The bonded sticks were randomly divided and assigned to be tested after one day [OD] (n 30 or six months [6 M] of water storage [6 M] (n = 30. Results: Two-way ANOVA and Tukey′s test showed that none of the adhesives showed degradation after 6 M. SB achieved the highest µTBS both in the [OD] (49.13 MPa and [6M] (40.27 MPa. Despite the highest values in both time evaluations, the µTBS of SB significantly reduced after 6M. LP showed the lowest µTBS in both periods of evaluation (18.35 and 18.34 MPa. Conclusions: Although a significant degradation was only observed for SB, this was the adhesive that showed the highest µTBS after 6 M of water storage.

  12. Integration a functional approach

    CERN Document Server

    Bichteler, Klaus

    1998-01-01

    This book covers Lebesgue integration and its generalizations from Daniell's point of view, modified by the use of seminorms. Integrating functions rather than measuring sets is posited as the main purpose of measure theory. From this point of view Lebesgue's integral can be had as a rather straightforward, even simplistic, extension of Riemann's integral; and its aims, definitions, and procedures can be motivated at an elementary level. The notion of measurability, for example, is suggested by Littlewood's observations rather than being conveyed authoritatively through definitions of (sigma)-algebras and good-cut-conditions, the latter of which are hard to justify and thus appear mysterious, even nettlesome, to the beginner. The approach taken provides the additional benefit of cutting the labor in half. The use of seminorms, ubiquitous in modern analysis, speeds things up even further. The book is intended for the reader who has some experience with proofs, a beginning graduate student for example. It might...

  13. Efficient photolytic C-H bond functionalization of alkylbenzene with hypervalent iodine(iii) reagent.

    Science.gov (United States)

    Sakamoto, Ryu; Inada, Tsubasa; Selvakumar, Sermadurai; Moteki, Shin A; Maruoka, Keiji

    2016-03-01

    A practical approach to radical C-H bond functionalization by the photolysis of a hypervalent iodine(iii) reagent is presented. The photolysis of [bis(trifluoroacetoxy)iodo]benzene (PIFA) leads to the generation of trifluoroacetoxy radicals, which allows the smooth transformation of various alkylbenzenes to the corresponding benzyl ester compounds under mild reaction conditions. PMID:26686276

  14. Comparison of theoretical approaches for computing the bond length alternation of polymethineimine

    Science.gov (United States)

    Jacquemin, Denis; Perpète, Eric A.; Chermette, Henry; Ciofini, Ilaria; Adamo, Carlo

    2007-01-01

    Using electron-correlated wavefunction approaches and several pure and hybrid density functionals combined with three atomic basis sets, we have optimized the ground-state geometry of increasingly long polymethineimine oligomers presenting all- trans and gliding-plane symmetries. It turns out that MP2 bond length alternations (BLA) are in good agreement with higher-order electron-correlated wavefunction approaches, whereas, for both conformers, large qualitative and quantitative discrepancies between MP2 and DFT geometries have been found. Indeed, all the selected GGA, meta-GGA and hybrid functionals tend to overestimate bond length equalization in extended polymethineimine structures. On the other hand, self-interaction corrections included in the ADSIC framework provide, in this particular case, a more efficient approach to predict the BLA for medium-size oligomers.

  15. Comparison of theoretical approaches for computing the bond length alternation of polymethineimine

    Energy Technology Data Exchange (ETDEWEB)

    Jacquemin, Denis [Laboratoire de Chimie Theorique Appliquee, Facultes Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur (Belgium)], E-mail: denis.jacquemin@fundp.ac.be; Perpete, Eric A. [Laboratoire de Chimie Theorique Appliquee, Facultes Universitaires Notre-Dame de la Paix, rue de Bruxelles, 61, B-5000 Namur (Belgium); Chermette, Henry [Laboratoire de Chimie Physique Theorique, Universite Claude Bernard, Lyon I Bat. 210, and CNRS UMR 5180 43, Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Ciofini, Ilaria; Adamo, Carlo [Ecole Nationale Superieure de Chimie de Paris, Laboratoire Electrochimie et Chimie Analytique, UMR CNRS ENSCP no. 7575, rue Pierre et Marie Curie, 11 F-75321 Paris Cedex 05 (France)

    2007-01-25

    Using electron-correlated wavefunction approaches and several pure and hybrid density functionals combined with three atomic basis sets, we have optimized the ground-state geometry of increasingly long polymethineimine oligomers presenting all-trans and gliding-plane symmetries. It turns out that MP2 bond length alternations (BLA) are in good agreement with higher-order electron-correlated wavefunction approaches, whereas, for both conformers, large qualitative and quantitative discrepancies between MP2 and DFT geometries have been found. Indeed, all the selected GGA, meta-GGA and hybrid functionals tend to overestimate bond length equalization in extended polymethineimine structures. On the other hand, self-interaction corrections included in the ADSIC framework provide, in this particular case, a more efficient approach to predict the BLA for medium-size oligomers.

  16. Site-selective and stereoselective functionalization of unactivated C–H bonds

    Science.gov (United States)

    Liao, Kuangbiao; Negretti, Solymar; Musaev, Djamaladdin G.; Bacsa, John; Davies, Huw M. L.

    2016-05-01

    The laboratory synthesis of complex organic molecules relies heavily on the introduction and manipulation of functional groups, such as carbon–oxygen or carbon–halogen bonds; carbon–hydrogen bonds are far less reactive and harder to functionalize selectively. The idea of C–H functionalization, in which C–H bonds are modified at will instead of the functional groups, represents a paradigm shift in the standard logic of organic synthesis. For this approach to be generally useful, effective strategies for site-selective C–H functionalization need to be developed. The most practical solutions to the site-selectivity problem rely on either intramolecular reactions or the use of directing groups within the substrate. A challenging, but potentially more flexible approach, would be to use catalyst control to determine which site in a particular substrate would be functionalized. Here we describe the use of dirhodium catalysts to achieve highly site-selective, diastereoselective and enantioselective C–H functionalization of n-alkanes and terminally substituted n-alkyl compounds. The reactions proceed in high yield, and functional groups such as halides, silanes and esters are compatible with this chemistry. These studies demonstrate that high site selectivity is possible in C–H functionalization reactions without the need for a directing or anchoring group present in the molecule.

  17. Metal nanoparticles functionalized with metal-ligand covalent bonds

    Science.gov (United States)

    Kang, Xiongwu

    Metal-organic contact has been recognized to play important roles in regulation of optical and electronic properties of nanoparticles. In this thesis, significant efforts have been devoted into synthesis of ruthenium nanoparticles with various metal-ligand interfacial linkages and investigation of their electronic and optical properties. Ruthenium nanoparticles were prepared by the self-assembly of functional group onto bare Ru colloid surface. As to Ru-alkyne nanoparticles, the formation of a Ru-vinylidene (Ru=C=CH--R) interfacial bonding linkage was confirmed by the specific reactivity of the nanoparticles with imine derivatives and olefin at the metal-ligand interface, as manifested in NMR, photoluminescence, and electrochemical measurements. Interestingly, it was found the electronic coupling coefficient (beta)for strongly depend upon such metal-ligand interfacial bonding. Next, such metal-ligand interfacial bonding was extended to ruthenium-nitrene pi bonds on ruthenium colloids, which were investigated by XPS. The nanoparticles exhibited a 1:1 atomic ratio of nitrogen to sulfur, consistent with that of sulfonyl nitrene fragments. In addition, the nanoparticle-bound nitrene moieties behaved analogously to azo derivatives, as manifested in UV-vis and fluorescence measurements. Further testimony of the formation of Ru=N interfacial linkages was highlighted in the unique reactivity of the nanoparticles with alkenes by imido transfer. Extensive conjugation between metal-ligand interfacial bond results in remarkable intraparticle charge delocalization on Ru-alkynide nanoparticles, which was manipulated by simple chemical reduction or oxidation. Charging of extra electrons into the nanoparticle cores led to an electron-rich metal core and hence red-shift of the triple bond stretching mode, lower binding energy of sp hybridized C 1s and dimmed fluorescence of nanoparticles. Instead, chemical oxidation resulted in the opposite impacts on these properties. By taking

  18. Phasor analysis of a synchronous generator: a bond graph approach

    NARCIS (Netherlands)

    Núñez Hernández, Israel; Breedveld, Peter C.; Weustink, Paul B.T.; Gonzalez-Avalos, Gilberto

    2014-01-01

    This paper presents the use of phasor bond graphs to obtain the steady-state behavior of a synchronous generator. The phasor bond graph elements are built using 2D multibonds, which represent the real and imaginary part of the phasor. The dynamic bond graph model of a salient-pole synchronous genera

  19. Density Functional Calculations on a Double Hydrogen-bonded Dimer

    Institute of Scientific and Technical Information of China (English)

    建方方; 赵朴素; 汪庆祥

    2005-01-01

    Density functional theory (DFT) calculations on a double hydrogen-bonded dimer of o-hydroxybenzoic acid were carried out at the B3LYP/6-31G* level. The optimized geometry of the dimer closely resembles that of the crystal. The calculated results show that the total energy of the dimer is much lower than the sum energies of the two monomers, and the average strength of the double hydrogen bonds is about 38.37 kJ/mol. In order to probe the origin of the interactions in the dimer, natural bond orbital analyses were performed. The thermodynamic properties of the title compound at different temperatures have also been calculated on the basis of vibrational analyses and AGT, the change of Gibbs free energy for the aggregation from monomer to the dimmer, is 26.47 k J/mol at 298.15 K and 0. 1 Mpa, implying the spontaneous process of forming the dimer. The correlation graphics of Som, Hom and temperatures is depicted.

  20. "Pricing Convertible Bonds with Credit Risk: A Duffie-Singleton Approach "(in Japanese)

    OpenAIRE

    Akihiko Takahashi; Takao Kobayashi; Naruhisa Nakagawa

    2001-01-01

    This paper proposes a method to price convertible bonds with credit risk using Duffie-Singleton approach to handle credit risk. As such it also provides a method to replicate convertibles by trading common stocks and corporate bonds of the issuing company. Empirical comparison with existing models which incorporate credit risk is provided using Japanese convertible bond data.

  1. Gradient Bundle Analysis: A Full Topological Approach to Chemical Bonding

    CERN Document Server

    Morgenstern, Amanda

    2016-01-01

    The "chemical bond" is a central concept in molecular sciences, but there is no consensus as to what a bond actually is. Therefore, a variety of bonding models have been developed, each defining the structure of molecules in a different manner with the goal of explaining and predicting chemical properties. This thesis describes the initial development of gradient bundle analysis (GBA), a chemical bonding model that creates a high resolution picture of chemical interactions within the charge density framework. GBA is based on concepts from the quantum theory of atoms in molecules (QTAIM), but uses a more complete picture of the topology and geometry of the electron charge density to understand and predict bonding interactions. Gradient bundles are defined as volumes bounded by zero-flux surfaces (ZFSs) in the gradient of the charge density with well-defined energies. The structure of gradient bundles provides an avenue for detecting the locations of valence electrons, which correspond to reactive regions in a ...

  2. Enantioselective functionalization of allylic C-H bonds following a strategy of functionalization and diversification.

    Science.gov (United States)

    Sharma, Ankit; Hartwig, John F

    2013-11-27

    We report the enantioselective functionalization of allylic C-H bonds in terminal alkenes by a strategy involving the installation of a temporary functional group at the terminal carbon atom by C-H bond functionalization, followed by the catalytic diversification of this intermediate with a broad scope of reagents. The method consists of a one-pot sequence of palladium-catalyzed allylic C-H bond oxidation under neutral conditions to form linear allyl benzoates, followed by iridium-catalyzed allylic substitution. This overall transformation forms a variety of chiral products containing a new C-N, C-O, C-S, or C-C bond at the allylic position in good yield with a high branched-to-linear selectivity and excellent enantioselectivity (ee ≤97%). The broad scope of the overall process results from separating the oxidation and functionalization steps; by doing so, the scope of nucleophile encompasses those sensitive to direct oxidative functionalization. The high enantioselectivity of the overall process is achieved by developing an allylic oxidation that occurs without acid to form the linear isomer with high selectivity. These allylic functionalization processes are amenable to an iterative sequence leading to (1,n)-functionalized products with catalyst-controlled diastereo- and enantioselectivity. The utility of the method in the synthesis of biologically active molecules has been demonstrated.

  3. A Non-Perturbative Approach to the Random-Bond Ising Model

    CERN Document Server

    Cabra, D C; Mussardo, G; Pujol, P

    1997-01-01

    We study the N -> 0 limit of the O(N) Gross-Neveu model in the framework of the massless form-factor approach. This model is related to the continuum limit of the Ising model with random bonds via the replica method. We discuss how this method may be useful in calculating correlation functions of physical operators. The identification of non-perturbative fixed points of the O(N) Gross-Neveu model is pursued by its mapping to a WZW model.

  4. Renormalisation group calculation of correlation functions for the 2D random bond Ising and Potts models

    CERN Document Server

    Dotsenko, V S; Pujol, P; Dotsenko, Vladimir; Picco, Marco; Pujol, Pierre

    1995-01-01

    We find the cross-over behavior for the spin-spin correlation function for the 2D Ising and 3-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation approach of the perturbation series around the conformal field theories representing the pure models. We obtain a crossover in the amplitude for the correlation function for the Ising model which doesn't change the critical exponent, and a shift in the critical exponent produced by randomness in the case of the Potts model. A comparison with numerical data is discussed briefly.

  5. Schwinger-boson approach to anisotropy ferrimagnetic chain with bond alternation

    Institute of Scientific and Technical Information of China (English)

    李殷翔; 陈斌

    2015-01-01

    We use the Schwinger-boson approach to study the anisotropy ferrimagnetic spin-(1/2,1) chain with bond alternation. Based on the effect of bond alternationδ, we obtain energy gap, free energy, and specific heat, respectively. The specific heat with larger bond alternation (δ >0.7) displays a peak at low temperature. Based on the effect of X X Z anisotropy parameter∆, we present excited spectrums, free energy, and specific heat, respectively.

  6. Covalent bonding from alchemical linear response density functional theory

    CERN Document Server

    Chang, K Y Samuel; Ramakrishnan, Raghunathan; von Lilienfeld, O Anatole

    2015-01-01

    We assess the predictive accuracy of linear response based estimates of changes in covalent bonding due to linear alchemical interpolations among molecules. We have investigated single bonds to hydrogen, as well as single, double, and triple bonds between main-group elements, occurring in small iso-electronic molecular spaces with atomic elements drawn from rows 2-3 in the $p$-block of the periodic table. Numerical evidence suggests that first order estimates of bonding potentials can achieve chemical accuracy if the alchemical interpolation connects molecules containing late elements in the periodic table (3$^{rd}$ and 4$^{th}$ row) and identical number of atoms and molecular geometries. For these interpolations, changes in bonding potential are near-linear in the coupling parameter, resulting in accurate Hellmann-Feynman predictions. Second order estimates for such interpolations yield worse predictions. The predictions become substantially worse if initial and final molecules differ not only in composition...

  7. Cavity partition and functionalization of a [2+3] organic molecular cage by inserting polar P[double bond, length as m-dash]O bonds.

    Science.gov (United States)

    Feng, Genfeng; Liu, Wei; Peng, Yuxin; Zhao, Bo; Huang, Wei; Dai, Yafei

    2016-07-28

    The cavity of a [2+3] organic molecular cage was partitioned and functionalized by inserting inner-directed P[double bond, length as m-dash]O bonds, which shows CO2 capture and CH4 exclusion due to the size-matching and polarity effects. Computational results demonstrate that the successful segmentation via polar P[double bond, length as m-dash]O bonds facilitates the CO2 molecules to reside selectively inside the cavity. PMID:27356151

  8. Haruspicy 3: The directed bond-animal generating function is not D-finite

    OpenAIRE

    Rechnitzer, Andrew

    2004-01-01

    While directed site-animals have been solved on several lattices, directed bond-animals remain unsolved on any non-trivial lattice. In this paper we demonstrate that the anisotropic generating function of directed bond-animals on the square lattice is fundamentally different from that of directed site-animals in that it is not differentiably finite. We also extend this result to directed bond-animals on hypercubic lattices. This indicates that directed bond-animals are unlikely to be solved b...

  9. Hydrogen bonding in the protic ionic liquid triethylammonium nitrate explored by density functional tight binding simulations

    CERN Document Server

    Zentel, Tobias

    2016-01-01

    The applicability of the density functional based tight binding (DFTB) method to the description of hydrogen bond dynamics and infrared spectroscopy is addressed for the exemplary protic ionic liquid triethylammonium nitrate. Potential energy curves for proton transfer in gas and liquid phase are shown to be comparable to high level coupled cluster theory in the thermally accessible range of bond lengths. Geometric correlations in the hydrogen bond dynamics are analyzed for a cluster of six ion pairs. Comparing DFTB and regular DFT data lends further support for the reliability of the DFTB method. Therefore, DFTB bulk simulations are performed to quantify the extent of geometric correlations in terms of Pauling's bond order model. Further, infrared (IR) absorption spectra are obtained and analyzed putting emphasis on the signatures of hydrogen bonding in the NH-stretching and far IR hydrogen bond range.

  10. Performance of a Nonempirical Density Functional on Molecules and Hydrogen-Bonded Complexes

    CERN Document Server

    Mo, Yuxiang; Car, Roberto; Staroverov, Viktor N; Scuseria, Gustavo E; Tao, Jianmin

    2016-01-01

    Recently, Tao and Mo (TM) derived a new meta-generalized gradient approximation based on a model exchange hole. In this work, the performance of this functional is assessed on standard test sets, using the 6-311++G(3df,3pd) basis set. These test sets include 223 G3/99 enthalpies of formation, 58 electron affinities, 8 proton affinities, 96 bond lengths, 82 harmonic vibrational frequencies, and 10 hydrogen-bonded molecular complexes. Our calculations show that the TM functional can achieve remarkable accuracy for most molecular properties, improving upon non-empirical density functionals considered here. In particular, it delivers the best accuracy for proton affinities, harmonic vibrational frequencies, and hydrogen-bonded dissociation energies and bond lengths, compared to other semilocal density-functional approximations considered in this work.

  11. Metal-activated histidine carbon donor hydrogen bonds contribute to metalloprotein folding and function.

    Science.gov (United States)

    Schmiedekamp, Ann; Nanda, Vikas

    2009-07-01

    Carbon donor hydrogen bonds are typically weak interactions that contribute less than 2 kcal/mol, and provide only modest stabilization in proteins. One exception is the class of hydrogen bonds donated by heterocyclic side chain carbons. Histidine is capable of particularly strong interactions through the Cepsilon(1) and Cdelta(2) carbons when the imidazole is protonated or bound to metal. Given the frequent occurrence of metal-bound histidines in metalloproteins, we characterized the energies of these interactions through DFT calculations on model compounds. Imidazole-water hydrogen bonding could vary from -11.0 to -17.0 kcal/mol, depending on the metal identity and oxidation state. A geometric search of metalloprotein structures in the PDB identified a number of candidate His C-H...O hydrogen bonds which may be important for folding or function. DFT calculations on model complexes of superoxide reductase show a carbon donor hydrogen bond positioning a water molecule above the active site.

  12. SCAN: An Efficient Density Functional Yielding Accurate Structures and Energies of Diversely-Bonded Materials

    Science.gov (United States)

    Sun, Jianwei

    The accuracy and computational efficiency of the widely used Kohn-Sham density functional theory (DFT) are limited by the approximation to its exchange-correlation energy Exc. The earliest local density approximation (LDA) overestimates the strengths of all bonds near equilibrium (even the vdW bonds). By adding the electron density gradient to model Exc, generalized gradient approximations (GGAs) generally soften the bonds to give robust and overall more accurate descriptions, except for the vdW interaction which is largely lost. Further improvement for covalent, ionic, and hydrogen bonds can be obtained by the computationally more expensive hybrid GGAs, which mix GGAs with the nonlocal exact exchange. Meta-GGAs are still semilocal in computation and thus efficient. Compared to GGAs, they add the kinetic energy density that enables them to recognize and accordingly treat different bonds, which no LDA or GGA can. We show here that the recently developed non-empirical strongly constrained and appropriately normed (SCAN) meta-GGA improves significantly over LDA and the standard Perdew-Burke-Ernzerhof GGA for geometries and energies of diversely-bonded materials (including covalent, metallic, ionic, hydrogen, and vdW bonds) at comparable efficiency. Often SCAN matches or improves upon the accuracy of a hybrid functional, at almost-GGA cost. This work has been supported by NSF under DMR-1305135 and CNS-09-58854, and by DOE BES EFRC CCDM under DE-SC0012575.

  13. Approaches to Pendent Groups' Functionalization of Polyimide

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Pendent groups' functionalization of polyimide is an optimum approach to improve its processability and achieve functionalized polyimide materials. There are two types of modification routes for pendent groups functionalization of polyimide: monomer route and macromolecular route. In this paper, various approaches for pendent groups' functionalization of polyimide are introduced. At the same time, a new method to achieve functional polyimide materials without decreasing its thermal stability and mechanical properties is mentioned.

  14. van der Waals Bonding in Layered Compounds from Advanced Density-Functional First-Principles Calculations

    OpenAIRE

    Björkman, T.; Gulans, A.; Krasheninnikov, A. V.; Nieminen, Risto M.

    2012-01-01

    Although the precise microscopic knowledge of van der Waals interactions is crucial for understanding bonding in weakly bonded layered compounds, very little quantitative information on the strength of interlayer interaction in these materials is available, either from experiments or simulations. Here, using many-body perturbation and advanced density-functional theory techniques, we calculate the interlayer binding and exfoliation energies for a large number of layered compounds and show tha...

  15. Symbolic Tensor Calculus -- Functional and Dynamic Approach

    CERN Document Server

    Woszczyna, A; Czaja, W; Golda, Z A

    2016-01-01

    In this paper, we briefly discuss the dynamic and functional approach to computer symbolic tensor analysis. The ccgrg package for Wolfram Language/Mathematica is used to illustrate this approach. Some examples of applications are attached.

  16. A simple approach for immobilization of gold nanoparticles on graphene oxide sheets by covalent bonding

    NARCIS (Netherlands)

    Pham, Tuan Anh; Choi, Byung Choon; Lim, Kwon Taek; Jeong, Yeon Tae

    2011-01-01

    Amino - functionalized gold nanoparticles with a diameter of around 5 nm were immobilized onto the surface of graphene oxide sheets (GOS) by covalent bonding through a simple amidation reaction. Pristine graphite was firstly oxidized and exfoliated to obtain GOS, which further were acylated with thi

  17. The anchoring function: parental authority and the parent-child bond.

    Science.gov (United States)

    Omer, Haim; Steinmetz, Sarit G; Carthy, Tal; von Schlippe, Arist

    2013-06-01

    Descriptions of parental authority and of the formation of a secure parent-child bond have remained unconnected in conceptualizations about parenting and child development. The parental anchoring function is here presented as an integrative metaphor for the two fields. Parents who fulfill an anchoring function offer a secure relational frame for the child, while also manifesting a stabilizing and legitimate kind of authority. The anchoring function enriches the two fields by: (1) adding a dimension of authority to the acknowledged functions of the safe haven and the secure base that are seen as core to a secure parent-child bond, and (2) adding considerations about the parent-child bond to Baumrind's classical description of authoritative parenting.

  18. The anchoring function: parental authority and the parent-child bond.

    Science.gov (United States)

    Omer, Haim; Steinmetz, Sarit G; Carthy, Tal; von Schlippe, Arist

    2013-06-01

    Descriptions of parental authority and of the formation of a secure parent-child bond have remained unconnected in conceptualizations about parenting and child development. The parental anchoring function is here presented as an integrative metaphor for the two fields. Parents who fulfill an anchoring function offer a secure relational frame for the child, while also manifesting a stabilizing and legitimate kind of authority. The anchoring function enriches the two fields by: (1) adding a dimension of authority to the acknowledged functions of the safe haven and the secure base that are seen as core to a secure parent-child bond, and (2) adding considerations about the parent-child bond to Baumrind's classical description of authoritative parenting. PMID:23763680

  19. Diagnostic Approach to Functional Recovery

    DEFF Research Database (Denmark)

    Havsteen, Inger; Madsen, Kristoffer H; Christensen, Hanne Krarup;

    2013-01-01

    to an acute ischemic lesion. Task-related as well as resting-state fMRI have been successfully applied to elucidate post-stroke remodeling of functional brain networks. This includes regional changes in neuronal activation as well as distributed changes in functional brain connectivity. Since fMRI is readily...... available and does not pose any adverse effects, repeated fMRI measurements provide unprecedented possibilities to prospectively assess the time course of reorganization in functional neural networks after stroke and relate the temporospatial dynamics of reorganization at the systems level to functional......, only up to 20-25% of patients are eligible to causal treatment. Further, care in a specialized stroke unit improves prognosis in all patients independent of age and stroke severity. Even when it is not possible to prevent tissue loss, the surviving brain areas of functional brain networks have...

  20. Bond slip detection of concrete-encased composite structure using shear wave based active sensing approach

    Science.gov (United States)

    Zeng, Lei; Parvasi, Seyed Mohammad; Kong, Qingzhao; Huo, Linsheng; Lim, Ing; Li, Mo; Song, Gangbing

    2015-12-01

    Concrete-encased composite structure exhibits improved strength, ductility and fire resistance compared to traditional reinforced concrete, by incorporating the advantages of both steel and concrete materials. A major drawback of this type of structure is the bond slip introduced between steel and concrete, which directly reduces the load capacity of the structure. In this paper, an active sensing approach using shear waves to provide monitoring and early warning of the development of bond slip in the concrete-encased composite structure is proposed. A specimen of concrete-encased composite structure was investigated. In this active sensing approach, shear mode smart aggregates (SAs) embedded in the concrete act as actuators and generate desired shear stress waves. Distributed piezoceramic transducers installed in the cavities of steel plates act as sensors and detect the wave response from shear mode SAs. Bond slip acts as a form of stress relief and attenuates the wave propagation energy. Experimental results from the time domain analysis clearly indicate that the amplitudes of received signal by lead zirconate titanate sensors decreased when bond slip occurred. In addition, a wavelet packet-based analysis was developed to compute the received signal energy values, which can be used to determine the initiation and development of bond slip in concrete-encased composite structure. In order to establish the validity of the proposed method, a 3D finite element analysis of the concrete-steel bond model is further performed with the aid of the commercial finite element package, Abaqus, and the numerical results are compared with the results obtained in experimental study.

  1. Spin-spin critical point correlation functions for the 2D random bond Ising and Potts models

    CERN Document Server

    Dotsenko, V S; Pujol, P; Vladimir Dotsenko; Marco Picco; Pierre Pujol

    1994-01-01

    We compute the combined two and three loop order correction to the spin-spin correlation functions for the 2D Ising and q-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation group approach for the perturbation series around the conformal field theories representing the pure models. We obtain corrections for the correlations functions which produce crossover in the amplitude but don't change the critical exponent in the case of the Ising model and which produce a shift in the critical exponent, due to randomness, in the case of the Potts model. Comparison with numerical data is discussed briefly.

  2. METAL NANOPARTICLES FUNCTIONALIZED WITH METAL-LIGAND COVALENT BONDS

    OpenAIRE

    Kang, Xiongwu

    2012-01-01

    Metal-organic contact has been recognized to play important roles in regulation of optical and electronic properties of nanoparticles. In this thesis, significant efforts have been devoted into synthesis of ruthenium nanoparticles with various metal-ligand interfacial linkages and investigation of their electronic and optical properties. Ruthenium nanoparticles were prepared by the self-assembly of functional group onto bare Ru colloid surface. As to Ru-alkyne nanoparticles, the formation of ...

  3. A Unified Bond Graph Modeling Approach for the Ejection Phase of the Cardiovascular System

    Directory of Open Access Journals (Sweden)

    LUBNA MOIN

    2016-07-01

    Full Text Available In this paper the unified Bond Graph model of the left ventricle ejection phase is presented, simulated and validated. The integro-differential and ordinary differential equations obtained from the bond graph models are simulated using ODE45 (Ordinary Differential Equation Solver on MATLAB and Simulink. The results, thus, obtained are compared with CVS (Cardiovascular System physiological data present in Simbiosys (a software for simulating biological systems and also with the CVS Wiggers diagram of heart cycle. As the cardiac activity is a multi domain process that includes mechanical, hydraulic, chemical and electrical events; therefore, for modeling such systems a unified modeling approach is needed. In this paper the unified Bond Graph model of the left ventricle ejection phase is proposed. The Bond Graph conventionalism approach is a graphical method principally powerful to portray multi-energy systems, as it is formulated on the portrayal of power exchanges. The model takes into account a simplified description of the left ventricle which is close to the medical investigation promoting the apperception and the dialogue between engineers and physiologists.

  4. Ferromagnetic bond of Li10 cluster: An alternative approach in terms of effective ferromagnetic sites

    Science.gov (United States)

    Donoso, Roberto; Rössler, Jaime; Llano-Gil, Sandra; Fuentealba, Patricio; Cárdenas, Carlos

    2016-09-01

    In this work, a model to explain the unusual stability of atomic lithium clusters in their highest spin multiplicity is presented and used to describe the ferromagnetic bonding of high-spin Li10 and Li8 clusters. The model associates the (lack of-)fitness of Heisenberg Hamiltonian with the degree of (de-)localization of the valence electrons in the cluster. It is shown that a regular Heisenberg Hamiltonian with four coupling constants cannot fully explain the energy of the different spin states. However, a more simple model in which electrons are located not at the position of the nuclei but at the position of the attractors of the electron localization function succeeds in explaining the energy spectrum and, at the same time, explains the ferromagnetic bond found by Shaik using arguments of valence bond theory. In this way, two different points of view, one more often used in physics, the Heisenberg model, and the other in chemistry, valence bond, come to the same answer to explain those atypical bonds.

  5. Performance of a Nonempirical Density Functional on Molecules and Hydrogen-Bonded Complexes

    OpenAIRE

    Mo, Yuxiang; Tian, Guocai; Car, Roberto; Viktor N. Staroverov; Scuseria, Gustavo E.; Tao, Jianmin

    2016-01-01

    Recently, Tao and Mo (TM) derived a new meta-generalized gradient approximation based on a model exchange hole. In this work, the performance of this functional is assessed on standard test sets, using the 6-311++G(3df,3pd) basis set. These test sets include 223 G3/99 enthalpies of formation, 58 electron affinities, 8 proton affinities, 96 bond lengths, 82 harmonic vibrational frequencies, and 10 hydrogen-bonded molecular complexes. Our calculations show that the TM functional can achieve rem...

  6. Nonorthogonal orbital based N-body reduced density matrices and their applications to valence bond theory. I. Hamiltonian matrix elements between internally contracted excited valence bond wave functions

    Science.gov (United States)

    Chen, Zhenhua; Chen, Xun; Wu, Wei

    2013-04-01

    In this series, the n-body reduced density matrix (n-RDM) approach for nonorthogonal orbitals and their applications to ab initio valence bond (VB) methods are presented. As the first paper of this series, Hamiltonian matrix elements between internally contracted VB wave functions are explicitly provided by means of nonorthogonal orbital based RDM approach. To this end, a more generalized Wick's theorem, called enhanced Wick's theorem, is presented both in arithmetical and in graphical forms, by which the deduction of expressions for the matrix elements between internally contracted VB wave functions is dramatically simplified, and the matrix elements are finally expressed in terms of tensor contractions of electronic integrals and n-RDMs of the reference VB self-consistent field wave function. A string-based algorithm is developed for the purpose of evaluating n-RDMs in an efficient way. Using the techniques presented in this paper, one is able to develop new methods and efficient algorithms for nonorthogonal orbital based many-electron theory much easier than by use of the first quantized formulism.

  7. The Trouble with Chemical Energy: Why Understanding Bond Energies Requires an Interdisciplinary Systems Approach

    OpenAIRE

    Cooper, Melanie M.; Klymkowsky, Michael W.

    2013-01-01

    Helping students understand “chemical energy” is notoriously difficult. Many hold inconsistent ideas about what energy is, how and why it changes during the course of a chemical reaction, and how these changes are related to bond energies and reaction dynamics. There are (at least) three major sources for this problem: 1) the way biologists talk about chemical energy (which is also the way we talk about energy in everyday life); 2) the macroscopic approach to energy concepts that is common in...

  8. Structure-directing factors when introducing hydrogen bond functionality to metal-organic frameworks

    OpenAIRE

    Forgan, Ross S.; Marshall, Ross J.; Struckmann, Mona; Bleine, Aurore; Long, De-Liang; Bernini, Maria Celeste; Fairen-Jimenez, David

    2015-01-01

    The introduction of H-bond donor/acceptor functionality into metal-organic frameworks (MOFs) can have a beneficial effect on their molecular recognition, uptake selectivity and catalytic properties. The changes in ligand geometry induced by incorporation of functional groups may also affect the topology and composition of the resultant MOFs. Herein, we present a comprehensive study of functional group incorporation into MOFs, linked by either Zn2+ paddlewheel units or monomeric Zn2+ corners, ...

  9. A Unified Approach to Generalized Stirling Functions

    Institute of Scientific and Technical Information of China (English)

    Tianxiao HE

    2012-01-01

    Here presented is a unified approach to generalized Stirling functions by using generalized factorial functions,k-Gamma functions,generalized divided difference,and the unified expression of Stirling numbers defined in[16].Previous well-known Stirling functions introduced by Butzer and Hauss[4],Butzer,Kilbas,and Trujilloet[6]and others are included as particular cases of our generalization.Some basic properties related to our general pattern such as their recursive relations,generating functions,and asymptotic properties are discussed,which extend the corresponding results about the Stirling numbers shown in[21]to the defined Stirling functions.

  10. Tensile bond strength of polyvinyl siloxane impressions bonded to a custom tray as a function of drying time: Part I.

    Science.gov (United States)

    Cho, G C; Donovan, T E; Chee, W W; White, S N

    1995-05-01

    Time-dependent bond strength studies of two polyvinyl siloxane impression materials to acrylic resin disks with their respective adhesives were studied to determine the optimal time for maximum bond strength. Six groups were tested with varying adhesive dry times of 0, 7, 15, and 60 minutes and 8 and 24 hours before testing. The results indicated that the bond strength of the adhesive increased at least twofold from time zero to 7 minutes adhesive dry time and peaked at 60 minutes for one of the materials and at 8 hours for the other. Bond strengths increased rapidly to the 15-minute test interval and then seemed to plateau. Both materials exhibited decreased adhesive bond strengths at 24 hours.

  11. Accurate first-principles structures and energies of diversely bonded systems from an efficient density functional

    Science.gov (United States)

    Sun, Jianwei; Remsing, Richard C.; Zhang, Yubo; Sun, Zhaoru; Ruzsinszky, Adrienn; Peng, Haowei; Yang, Zenghui; Paul, Arpita; Waghmare, Umesh; Wu, Xifan; Klein, Michael L.; Perdew, John P.

    2016-09-01

    One atom or molecule binds to another through various types of bond, the strengths of which range from several meV to several eV. Although some computational methods can provide accurate descriptions of all bond types, those methods are not efficient enough for many studies (for example, large systems, ab initio molecular dynamics and high-throughput searches for functional materials). Here, we show that the recently developed non-empirical strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) within the density functional theory framework predicts accurate geometries and energies of diversely bonded molecules and materials (including covalent, metallic, ionic, hydrogen and van der Waals bonds). This represents a significant improvement at comparable efficiency over its predecessors, the GGAs that currently dominate materials computation. Often, SCAN matches or improves on the accuracy of a computationally expensive hybrid functional, at almost-GGA cost. SCAN is therefore expected to have a broad impact on chemistry and materials science.

  12. Atom probe tomography simulations and density functional theory calculations of bonding energies in Cu3Au

    KAUST Repository

    Boll, Torben

    2012-10-01

    In this article the Cu-Au binding energy in Cu3Au is determined by comparing experimental atom probe tomography (APT) results to simulations. The resulting bonding energy is supported by density functional theory calculations. The APT simulations are based on the Müller-Schottky equation, which is modified to include different atomic neighborhoods and their characteristic bonds. The local environment is considered up to the fifth next nearest neighbors. To compare the experimental with simulated APT data, the AtomVicinity algorithm, which provides statistical information about the positions of the neighboring atoms, is applied. The quality of this information is influenced by the field evaporation behavior of the different species, which is connected to the bonding energies. © Microscopy Society of America 2012.

  13. Silver-catalyzed silicon-hydrogen bond functionalization by carbene insertion.

    Science.gov (United States)

    Iglesias, M José; Nicasio, M Carmen; Caballero, Ana; Pérez, Pedro J

    2013-01-28

    The catalytic functionalization of silicon-hydrogen bonds by means of the insertion of carbene units :CHCO(2)Et from ethyl diazoacetate (EDA) has been achieved using a silver-based catalyst, constituting the first example of this metal to promote this transformation. Competition experiments have revealed that the relative reactivity of substituted silanes depends on the bond dissociation energy of the Si-H bond (tertiary > secondary > primary for ethyl substituted). In the presence of bulky substituents such order reverts to secondary > primary ≈ tertiary (for phenyl substituted). Screening with other diazo compounds has shown that N(2)C(Ph)CO(2)Et displays similar reactivity to that of EDA, whereas other N(2)C(R)CO(2)Et (R = Me, CO(2)Et) gave lower conversions. PMID:23114570

  14. Density Functional Theory Study of Hydrogen Bonds of Bipyridine with 1,3,5-Benzenetricarboxylic Acid

    Institute of Scientific and Technical Information of China (English)

    LI Quan; ZHAO Keqing

    2009-01-01

    The hydrogen-bonded dimer and trimer formed between 1,3,5-benzenetricarboxylic acid and bipyridine have been investigated using a density functional theory(DFT)method and 6-31++G** basis set.The interaction enerstretching modes in the dimer and trimer red-shifted relative to those of the 1,3,5-benzenetricarhoxylic acid monomer.The natural bond orbit analysis shows that the inter-molecular charge transfers are 0.60475e and 1.20225e for the dimer and trimer,respectively.Thermodynamic analysis indicates that the formation of trimer is an exothermic H-O intermolecular hydrogen bonds between bipyridine and 1,3,5-benzenetricarboxylic acid,which is in good agreement with the experimental results.

  15. Analysis of radial basis function interpolation approach

    Institute of Scientific and Technical Information of China (English)

    Zou You-Long; Hu Fa-Long; Zhou Can-Can; Li Chao-Liu; Dunn Keh-Jim

    2013-01-01

    The radial basis function (RBF) interpolation approach proposed by Freedman is used to solve inverse problems encountered in well-logging and other petrophysical issues. The approach is to predict petrophysical properties in the laboratory on the basis of physical rock datasets, which include the formation factor, viscosity, permeability, and molecular composition. However, this approach does not consider the effect of spatial distribution of the calibration data on the interpolation result. This study proposes a new RBF interpolation approach based on the Freedman's RBF interpolation approach, by which the unit basis functions are uniformly populated in the space domain. The inverse results of the two approaches are comparatively analyzed by using our datasets. We determine that although the interpolation effects of the two approaches are equivalent, the new approach is more flexible and beneficial for reducing the number of basis functions when the database is large, resulting in simplification of the interpolation function expression. However, the predicted results of the central data are not sufficiently satisfied when the data clusters are far apart.

  16. Developing density functional theory for Bose-Einstein condensates. The case of chemical bonding

    International Nuclear Information System (INIS)

    Since the nowadays growing interest in Bose-Einstein condensates due to the expanded experimental evidence on various atomic systems within optical lattices in weak and strong coupling regimes, the connection with Density Functional Theory is firstly advanced within the mean field framework at three levels of comprehension: the many-body normalization condition, Thomas-Fermi limit, and the chemical hardness closure with the inter-bosonic strength and universal Hohenberg-Kohn functional. As an application the traditional Heitler-London quantum mechanical description of the chemical bonding for homopolar atomic systems is reloaded within the non-linear Schrödinger (Gross-Pitaevsky) Hamiltonian; the results show that a two-fold energetic solution is registered either for bonding and antibonding states, with the bosonic contribution being driven by the square of the order parameter for the Bose-Einstein condensate density in free (gas) motion, while the associate wave functions remain as in classical molecular orbital model

  17. Developing density functional theory for Bose-Einstein condensates. The case of chemical bonding

    Energy Technology Data Exchange (ETDEWEB)

    Putz, Mihai V., E-mail: mvputz@cbg.uvt.ro [Laboratory of Physical and Computational Chemistry, Chemistry Department, West University of Timisoara, Str. Pestalozzi No. 16, 300115 Timisoara, Romania and Theoretical Physics Institute, Free University Berlin, Arnimallee 14, 14195 Berlin (Germany)

    2015-01-22

    Since the nowadays growing interest in Bose-Einstein condensates due to the expanded experimental evidence on various atomic systems within optical lattices in weak and strong coupling regimes, the connection with Density Functional Theory is firstly advanced within the mean field framework at three levels of comprehension: the many-body normalization condition, Thomas-Fermi limit, and the chemical hardness closure with the inter-bosonic strength and universal Hohenberg-Kohn functional. As an application the traditional Heitler-London quantum mechanical description of the chemical bonding for homopolar atomic systems is reloaded within the non-linear Schrödinger (Gross-Pitaevsky) Hamiltonian; the results show that a two-fold energetic solution is registered either for bonding and antibonding states, with the bosonic contribution being driven by the square of the order parameter for the Bose-Einstein condensate density in free (gas) motion, while the associate wave functions remain as in classical molecular orbital model.

  18. Hydrogen-bonded Intramolecular Charge Transfer Excited State of Dimethylaminobenzophenone using Time Dependent Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    Yu-ling Chu; Zhong Yang; Zhe-feng Pan; Jing Liu; Yue-yi Han; Yong Ding; Peng Song

    2012-01-01

    Density functional theory and time-dependent density-functional theory have been used to investigate the photophysical properties and relaxation dynamics of dimethylaminobenzophenone (DMABP) and its hydrogen-bonded DMABP-MeOH dimer.It is found that,in nonpolar aprotic solvent,the transitions from S0 to S1 and S2 states of DMABP have both n→π* and π→π* characters,with the locally excited feature mainly located on the C=O group and the partial CT one characterized by electron transfer mainly from the dimethylaminophenyl group to the C=O group.But when the intermolecular hydrogen bond C=O…H-O is formed,the highly polar intramolecular charge transfer character switches over to the first excited state of DMABP-MeOH dimer and the energy difference between the two lowlying electronically excited states increases.To gain insight into the relaxation dynamics of DMABP and DMABP-MeOH dimer in the excited state,the potential energy curves for conformational relaxation are calculated.The formation of twisted intramolecular charge transfer state via diffusive twisting motion of the dimethylamino/dimethylaminophenyl groups is found to be the major relaxation process.In addition,the decay of the S1 state of DMABP-MeOH dimer to the ground state,through nonradiative intermolecular hydrogen bond stretching vibrations,is facilitated by the formation of the hydrogen bond between DMABP and alcohols.

  19. Enhancement of dispersion and bonding of graphene-polymer through wet transfer of functionalized graphene oxide

    Directory of Open Access Journals (Sweden)

    F. Sharif

    2012-12-01

    Full Text Available Dispersion of nanomaterials in polymeric matrices plays an important role in determining the final properties of the composites. Dispersion in nano scale, and especially in single layers, provides best opportunity for bonding. In this study, we propose that by proper functionalization and mixing strategy of graphene its dispersion, and bonding to the polymeric matrix can be improved. We then apply this strategy to graphene-epoxy system by amino functionalization of graphene oxide (GO. The process included two phase extraction, and resulted in better dispersion and higher loading of graphene in epoxy matrix. Rheological evaluation of different graphene-epoxy dispersions showed a rheological percolation threshold of 0.2 vol% which is an indication of highly dispersed nanosheets. Observation of the samples by optical microscopy, scanning electron microscopy (SEM, and atomic force microscopy (AFM, showed dispersion homogeneity of the sheets at micro and nano scales. Study of graphene-epoxy composites showed good bonding between graphene and epoxy. Mechanical properties of the samples were consistent with theoretical predictions for ideal composites indicating molecular level dispersion and good bonding between nanosheets and epoxy matrix.

  20. An inverse approach for elucidating dendritic function

    Directory of Open Access Journals (Sweden)

    Benjamin Torben-Nielsen

    2010-09-01

    Full Text Available We outline an inverse approach for investigating dendritic function-structure relationships by optimizing dendritic trees for a-priori chosen computational functions. The inverse approach can be applied in two different ways. First, we can use it as a `hypothesis generator' in which we optimize dendrites for a function of general interest. The optimization yields an artificial dendrite that is subsequently compared to real neurons. This comparison potentially allows us to propose hypotheses about the function of real neurons. In this way, we investigated dendrites that optimally perform input-order detection. Second, we can use it as a `function confirmation' by optimizing dendrites for functions hypothesized to be performed by classes of neurons. If the optimized, artificial, dendrites resemble the dendrites of real neurons the artificial dendrites corroborate the hypothesized function of the real neuron. Moreover, properties of the artificial dendrites can lead to predictions about yet unmeasured properties. In this way, we investigated wide-field motion integration performed by the VS cells of the fly visual system. In outlining the inverse approach and two applications, we also elaborate on the nature of dendritic function. We furthermore discuss the role of optimality in assigning functions to dendrites and point out interesting future directions.

  1. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  2. Push-out bond strength and SEM evaluation of a new bonding approach into the root canal

    Directory of Open Access Journals (Sweden)

    Carlos Augusto Carvalho

    2012-12-01

    Full Text Available OBJECTIVE: This study evaluated the performance of different adhesive systems in fiber post placement aiming to clarify the influence of different hydrophobic experimental blend adhesives, and of one commercially available adhesive on the frictional retention during a luting procedure. MATERIAL AND METHODS: One luting agent (70 Wt% BisGMA, 28.5% TEGDMA; 1.5% p-tolyldiethanolamine to cement fiber posts into root canals was applied with 4 different adhesive combinations: Group 1: The etched roots were rinsed with water for 30 s to remove the phosphoric acid, then rinsed with 99.6% ethanol for 30 s, and blotdried. A trial adhesive (base to catalyst on a 1:1 ratio was used with an experimental luting agent (35% Bis-GMA, 14.37% TeGDMA, 0.5% eDMAB, 0.13% CQ; Group 2: A trial adhesive (base to catalyst on a 1:2 ratio was luted as in Group 1; Group 3: One-Step Plus (OSP, Bisco Inc. following the ethanol bonding technique in combination with the luting agent as in Group 1; Group 4: OSP strictly following the manufacturer's instructions using the luting agent as in Group 1. The groups were challenged with push-out tests. Posted root slices were loaded until post segment extrusion in the apical-coronal direction. Failure modes were analyzed under scanning electron microscopy. RESULTS: Push-out strength was not significantly influenced by the luting agent (p>0.05. No statistically significant differences among the tested groups were found as Group 1 (exp 1 - ethanol-wet bonding technique=Group 2 (exp 2 - ethanol-wet bonding technique=Group 3 (OSP - ethanol-wet bonding technique=Group 4 (control, OSP - water-wet bonding technique (p>0.05. The dominating failure modes in all the groups were cohesive/adhesive failures, which were predominantly observed on the post/luting agent interface. CONCLUSIONS: The results of this study support the hypothesis that the proposal to replace water with ethanol to bond fiber posts to the root canal using highly hydrophobic

  3. Electronic Structure of Dangling Bonds in Amorphous Silicon Studied via a Density-Matrix Functional Method

    OpenAIRE

    Hennig, R. G.; Fedders, P. A.; Carlsson, A. E.

    2002-01-01

    A structural model of hydrogenated amorphous silicon containing an isolated dangling bond is used to investigate the effects of electron interactions on the electronic level splittings, localization of charge and spin, and fluctuations in charge and spin. These properties are calculated with a recently developed density-matrix correlation-energy functional applied to a generalized Anderson Hamiltonian, consisting of tight-binding one-electron terms parametrizing hydrogenated amorphous silicon...

  4. Stressful parental bonding exaggerate the functional and emotional disturbances of primary dysmenorrhea

    OpenAIRE

    Kai XU; Chen, Liuxi; Fu, Lingyun; Mao, Hongjing; Liu, Jian; Wang, Wei

    2014-01-01

    Background: Some evidence suggests that women with primary dysmenorrhea (or painful period) often have traumatic experience with parental attachments, but the exact relationship between styles of the parental bonding and the detailed aspects of the disorder is unclear.Methods: From university-student women, we invited 50 primary dysmenorrhea patients and 111 healthy volunteers to undergo tests of the functional and emotional measure of dysmenorrhea (FEMD), the Family Relationship Questionnair...

  5. Density Functional Theory Study of Red-shifted Hydrogen Bonds of 4-Pyridinemethanol with Water

    Institute of Scientific and Technical Information of China (English)

    LI Quan; CAI Jing; CHEN Jun-Rong; ZHAO Ke-Qing

    2008-01-01

    The hydrogen bonds of 1∶1 and 1∶2 complexes formed between 4-pyridinemethanol and water have been investigated using a density functional theory (DFT) method and 6-311++G** basis set, and three and eight stable geometries have been obtained for 1∶1 and 1∶2 complexes, respectively.The interaction energy is -20.536 and -44.256 kJ/mol for the most stable 1∶1 and 1∶2 complexes, respectively, after the basis set superposition error and zero-point corrections.The formation of O-H…N(O) hydrogen bonds makes O-H symmetric stretching modes in the complexes red-shifted relative to those of the monomer.The natural bond orbit analysis indicates that the intermolecular charge transfer between 4-pyridinemethanol and water is 0.02642 e and 0.03813 e for the most stable 1∶1 and 1∶2 complexes, respectively.In addition, TD-B3LYP/6-311++G** calculations show that formation of water-OH…N and water-OH…OH hydrogen bonds makes maximum absorbance wavelength λmax blue-shifted 8-16 nm and red-shifted 4-11 nm compared to that of 4-pyridinemethanol monomer molecule, respectively.

  6. A functional approach to the TMJ disorders.

    Science.gov (United States)

    Deodato, F; Cristiano, S; Trusendi, R; Giorgetti, R

    2003-01-01

    This manuscript describes our conservative approach to treatment of TMJ disorders. The method we use had been suggested by Rocabado - its aims are: joint distraction by the elimination of compression, restoration of physiologic articular rest, mobilization of the soft tissues, and whenever possible, to improve the condyle-disk-glenoid fossa relationship. To support these claims two clinical cases are presented where the non-invasive therapy was successful. The results obtained confirm the validity of this functional approach.

  7. Functionalization and bioimmobilization of silicon surfaces with Si–N bonded monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Masood, Muhammad Nasir, E-mail: chemnasir_76@yahoo.com [Bios Lab on a Chip Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands); Department of Physics and Applied Mathematics, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad (Pakistan); Carlen, Edwin T.; Berg, Albert van den [Bios Lab on a Chip Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede (Netherlands)

    2015-05-15

    Highlights: • Chemistry of Ethylene diamine (EDA) studied by X-ray photoelectron spectroscopy (XPS) on hydrogen terminated Si (1 1 1) surface under UV-irradiation. • Fast, efficient and selective surface modification via symmetric functional molecule. • Do not involve protection and deprotection steps which deteoriate the monolayer integrity, time consuming and expensive. • Si–N bond remain intact on sub-oxidized silicon surface. • Free amine groups availability for bioimmobilization. • Selectivity and sensitivity was demonstrated by SEM, fluorscence and electrochemical (C–V) measurements. - Abstract: A new method for selective surface functionalization of silicon with a silicon–nitrogen bonded (Si–N) monolayer and subsequent bioimmobilization is presented. The Si–N monolayer was studied using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), fluorescence spectroscopy, and capacitance–voltage (C–V) measurements using an electrolyte insulator semiconductor (EIS) sensor. A symmetric ethylene diamine (EDA, C{sub 2}H{sub 4} (NH{sub 2}){sub 2}) molecule was used as a precursor compound for monolayer formation in an inert environment in the liquid phase. XPS results show the attachment of EDA molecules proceeds via dissociative and dative bond formation whereas free amine groups on the surface were used for further immobilization of biomolecules. SEM shows selective functionalization and bioimmobilization on a patterned surface such as a silicon nanowire on silicon oxide substrate. Biosensing experiments with bioimmobilized surfaces were carried out in aqueous buffer and show high sensitivity for biosensing.

  8. [Partial lease squares approach to functional analysis].

    Science.gov (United States)

    Preda, C

    2006-01-01

    We extend the partial least squares (PLS) approach to functional data represented in our models by sample paths of stochastic process with continuous time. Due to the infinite dimension, when functional data are used as a predictor for linear regression and classification models, the estimation problem is an ill-posed one. In this context, PLS offers a simple and efficient alternative to the methods based on the principal components of the stochastic process. We compare the results given by the PLS approach and other linear models using several datasets from economy, industry and medical fields. PMID:17124795

  9. Green function approach for scattering quantum walks

    CERN Document Server

    Andrade, F M; 10.1103/PhysRevA.84.042343

    2011-01-01

    In this work a Green function approach for scattering quantum walks is developed. The exact formula has the form of a sum over paths and always can be cast into a closed analytic expression for arbitrary topologies and position dependent quantum amplitudes. By introducing the step and path operators, it is shown how to extract any information about the system from the Green function. The method relevant features are demonstrated by discussing in details an example, a general diamond-shaped graph.

  10. Bond centred functions in relativistic and non-relativistic calculations for diatomics

    International Nuclear Information System (INIS)

    In this paper, we discuss the performance of molecular basis sets consisting of atomic centred (AC) functions augmented with bond centred (BC) functions in relativistic and non-relativistic calculations carried out at the Hartree-Fock and several correlated levels of approximation. While usually non-correlated calculations employing BC functions can be performed at a lower computational cost as compared with those making use of energy optimized AC basis sets, the correlated calculations are always more accurate and less expensive with the latter. It is demonstrated that both correlated or non-correlated calculations always benefit from the addition of a few BC functions with a moderate increase of computational effort. The performance of basis sets containing even-tempered BC functions is also studied and their usage is advocated in case of relativistic calculations

  11. Hybrid density functional study on lattice vibration, thermodynamic properties, and chemical bonding of plutonium monocarbide

    Science.gov (United States)

    Rong, Yang; Bin, Tang; Tao, Gao; BingYun, Ao

    2016-06-01

    Hybrid density functional theory is employed to systematically investigate the structural, magnetic, vibrational, thermodynamic properties of plutonium monocarbide (PuC and PuC0.75). For comparison, the results obtained by DFT, DFT + U are also given. For PuC and PuC0.75, Fock-0.25 hybrid functional gives the best lattice constants and predicts the correct ground states of antiferromagnetic (AFM) structure. The calculated phonon spectra suggest that PuC and PuC0.75 are dynamically stable. Values of the Helmholtz free energy ΔF, internal energy ΔE, entropy S, and constant-volume specific heat C v of PuC and PuC0.75 are given. The results are in good agreement with available experimental or theoretical data. As for the chemical bonding nature, the difference charge densities, the partial densities of states and the Bader charge analysis suggest that the Pu-C bonds of PuC and PuC0.75 have a mixture of covalent character and ionic character. The effect of carbon vacancy on the chemical bonding is also discussed in detail. We expect that our study can provide some useful reference for further experimental research on the phonon density of states, thermodynamic properties of the plutonium monocarbide. Project supported by the National Natural Science Foundation of China (Grant Nos. 21371160 and 21401173).

  12. Role of functional groups in surface bonding of planar π-conjugated molecules

    Science.gov (United States)

    Bauer, Oliver; Mercurio, Giuseppe; Willenbockel, Martin; Reckien, Werner; Heinrich Schmitz, Christoph; Fiedler, Benjamin; Soubatch, Serguei; Bredow, Thomas; Tautz, Frank Stefan; Sokolowski, Moritz

    2012-12-01

    The trends in the bonding mechanism of 3,4,9,10-perylenetetracarboxylic acid dianhydride (PTCDA) to the Ag(111), Ag(100), and Ag(110) surfaces were analyzed on the basis of data obtained from x-ray standing waves and dispersion-corrected density functional theory. Of importance are the attractive local O-Ag bonds on the anhydride groups. They are the shorter, the more open the surface is, and lead even to partly repulsive interactions between the perylene core and the surface. In parallel, there is an increasing charge donation from the Ag surface into the π system of the PTCDA. This synergism explains the out-of-plane distortion of the adsorbed PTCDA and the surface buckling.

  13. C-F sp(2) bond functionalization mediated by niobium complexes.

    Science.gov (United States)

    Nechayev, Michael; Gianetti, Thomas L; Bergman, Robert G; Arnold, John

    2015-12-01

    Insertion chemistry of isocyanide molecules was used to functionalize C-F sp(2) bonds after their oxidative addition across the metal center in a β-diketiminate niobium(iii) imido complex (BDI)Nb(N(t)Bu)(C6H6). The complexes formed, 3a-b ([BDI]Nb(PhC[double bond, length as m-dash]N)(N(t)Bu)(F) (R = 1,6-diisopropylphenyl, tert-butyl), were characterized by NMR spectroscopy and X-ray analysis. Further treatment with phenylsilane induced H/F exchange under mild conditions, which was followed by hydride transfer to the inserted isocyanide. Divergent reactivity was observed when the two analogous aryl and tert-butyl isocyanide insertion products were treated with phenylsilane. PMID:26216334

  14. Spectroscopic examinations of hydrogen bonding in hydroxy-functionalized ADMET chemistry.

    Science.gov (United States)

    Thompson, Donovan L; Wagener, Kenneth B; Schulze, Ulrich; Voit, Brigitte; Jehnichen, Dieter; Malanin, Mikhail

    2015-01-01

    Wide-angle X-ray scattering (WAXS) and temperature-dependent Fourier transform infrared spectroscopy (FTIR) spectroscopy are used to study hydrogen bonding interactions of a hydroxyl-functionalized polyethylene (PE) prepared by acyclic diene metathesis (ADMET) chemistry. The hydroxyl polymer exhibits an orthorhombic unit cell structure with characteristic reflection planes at (110) and (200), comparable to pure crystalline PE. These data unequivocally demonstrate that the OH branch is excluded from the PE lamellae. Furthermore, the polymer melts 100 °C higher than all previous analogous polymers possessing precision placed long aliphatic branches that also are excluded from PE lamellae. Temperature-dependent FTIR spectroscopy from ambient to 150 °C, followed by cooling to 125 °C supports exclusion of the hydroxyl group from the crystalline lattice. It is concluded that these hydroxyl groups form stable physical networks in the amorphous region via hydrogen bonding and are important for the overall morphology of such polymers. PMID:25393938

  15. An application of the van der Waals density functional: Hydrogen bonding and stacking interactions between nucleobases.

    Science.gov (United States)

    Cooper, Valentino R; Thonhauser, T; Langreth, David C

    2008-05-28

    We apply the van der Waals density functional (vdW-DF) to study hydrogen bonding and stacking interactions between nucleobases. The excellent agreement of our results with high level quantum chemical calculations highlights the value of the vdW-DF for first-principles investigations of biologically important molecules. Our results suggest that, in the case of hydrogen-bonded nucleobase pairs, dispersion interactions reduce the cost of propeller twists while having a negligible effect on buckling. Furthermore, the efficient scaling of DFT methods allowed for the easy optimization of separation distance between nucleobase stacks, indicating enhancements in the interaction energy of up to 3 kcalmol over previous fixed distance calculations. We anticipate that these results are significant for extending the vdW-DF method to model larger vdW complexes and biological molecules. PMID:18513005

  16. Introducing linear functions: an alternative statistical approach

    Science.gov (United States)

    Nolan, Caroline; Herbert, Sandra

    2015-12-01

    The introduction of linear functions is the turning point where many students decide if mathematics is useful or not. This means the role of parameters and variables in linear functions could be considered to be `threshold concepts'. There is recognition that linear functions can be taught in context through the exploration of linear modelling examples, but this has its limitations. Currently, statistical data is easily attainable, and graphics or computer algebra system (CAS) calculators are common in many classrooms. The use of this technology provides ease of access to different representations of linear functions as well as the ability to fit a least-squares line for real-life data. This means these calculators could support a possible alternative approach to the introduction of linear functions. This study compares the results of an end-of-topic test for two classes of Australian middle secondary students at a regional school to determine if such an alternative approach is feasible. In this study, test questions were grouped by concept and subjected to concept by concept analysis of the means of test results of the two classes. This analysis revealed that the students following the alternative approach demonstrated greater competence with non-standard questions.

  17. A Functional Approach to User Guides

    DEFF Research Database (Denmark)

    Nielsen, Sandro

    2007-01-01

    The functional approach opens up exciting new possibilities for theoretical and practical lexicography. It encourages lexicographers to adopt a new way of thinking when planning and compiling dictionaries and when discussing and developing new lexicographic principles. One area in which it impacts...... on lexicography and lexicographic products is the writing of a really crafted and valuable user guide for instance by giving increased consideration to the user perspective. This involves the identification of the functions of the dictionary in terms of communication-oriented and cognitive functions, which helps...... function-related dictionary components, thereby highlighting the fact that a dictionary is much more than a list of words and that it can be used to solve specific function-related problems. One way in which to write really crafted and valuable user guides is to accentuate the relevant communication...

  18. Bonding in elemental boron: a view from electronic structure calculations using maximally localized Wannier functions

    Science.gov (United States)

    Ogitsu, Tadashi; Gygi, Francois; Reed, John; Schwegler, Eric; Galli, Giulia

    2007-03-01

    Boron exhibits the most complex structure of all elemental solids, with more than 300 atoms per unit cell arranged in interconnecting icosahedra, and some crystallographic positions occupied with a probability of less than one. The precise determination of the ground state geometry of boron---the so-called β-boron structure--has been elusive and its electronic and bonding properties have been difficult to rationalize. Using lattice model Monte Carlo optimization techniques and ab-initio simulations, we have shown that a defective, quasi-ordered β solid is the most stable structure at zero as well as finite T. In the absence of partially occupied sites (POS), the perfect β-boron crystal is unstable; the presence of POS lower its internal energy below that of an ordered α-phase, not mere an entropic effect. We present a picture of the intricate and unique bonding in boron based on maximally localized Wannier (MLWF) functions, which indicates that the presence of POS provides a subtle, yet essential spatial balance between electron deficient and fully saturated bonds. This work was performed under the auspices of the U.S. Dept. of Energy at the University of California/ LLNL under contract no. W-7405-Eng-48.

  19. Density Functional Calculations of C-NO2 Bond Dissociation Energies for Nitroalkanes Molecules

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Bond dissociation energies for the removal of nitrogen dioxide group in some nitroalkane energetic materials have been calculated by using the three hybrid density functional theory (DFT) methods B3LYP, B3PW91 and B3P86 with 6-31g** and 6-311g** basis sets. The computed BDEs have been compared with the available experimental results. It is found that the B3P86 method with 6-31g** and 6-311g** basis sets can obtain satisfactory bond dissociation energies (BDEs), which are in extraordinary agreement with the experimental data. Considering the smaller mean absolute deviation and maximum difference, the reliable B3P86/6-311g** method was recommended to compute the BDEs for the removal of nitrogen dioxide group in the nitroalkane energetic materials. Using the method, the BDEs of 8 other nitroalkane energetic materials have been calculated and the maximum difference from experimental value is 1.76 kcal·mol-1 (for the BDE of tC4H9-NO2), which further proves the reliability of B3P86/6-311g** method. In addition, it is noted that the BDEs of C-NO2 bond change slightly for main chain nitroalkane compounds with the maximum difference of only 3.43 kcal mol-1.

  20. Tuning and probing interfacial bonding channels for a functionalized organic molecule by surface modification

    Science.gov (United States)

    Mercurio, G.; Bauer, O.; Willenbockel, M.; Fiedler, B.; Sueyoshi, T.; Weiss, C.; Temirov, R.; Soubatch, S.; Sokolowski, M.; Tautz, F. S.

    2013-03-01

    The potassium-induced missing row reconstruction of Ag(110) is used to selectively modify the local chemical interaction between the functional anhydride groups of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and Ag(110). We find a significant upward shift of the anhydride groups, while the adsorption height of the perylene core is essentially preserved. This demonstrates an attractive perylene/substrate interaction for PTCDA/K:Ag(110), elucidating also the bonding situation for the potassium-free system.

  1. Understanding the bonding nature of uranyl ion and functionalized graphene: a theoretical study.

    Science.gov (United States)

    Wu, Qun-Yan; Lan, Jian-Hui; Wang, Cong-Zhi; Xiao, Cheng-Liang; Zhao, Yu-Liang; Wei, Yue-Zhou; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-03-20

    Studying the bonding nature of uranyl ion and graphene oxide (GO) is very important for understanding the mechanism of the removal of uranium from radioactive wastewater with GO-based materials. We have optimized 22 complexes between uranyl ion and GO applying density functional theory (DFT) combined with quasi-relativistic small-core pseudopotentials. The studied oxygen-containing functional groups include hydroxyl, carboxyl, amido, and dimethylformamide. It is observed that the distances between uranium atoms and oxygen atoms of GO (U-OG) are shorter in the anionic GO complexes (uranyl/GO(-/2-)) compared to the neutral GO ones (uranyl/GO). The formation of hydrogen bonds in the uranyl/GO(-/2-) complexes can enhance the binding ability of anionic GO toward uranyl ions. Furthermore, the thermodynamic calculations show that the changes of the Gibbs free energies in solution are relatively more negative for complexation reactions concerning the hydroxyl and carboxyl functionalized anionic GO complexes. Therefore, both the geometries and thermodynamic energies indicate that the binding abilities of uranyl ions toward GO modified by hydroxyl and carboxyl groups are much stronger compared to those by amido and dimethylformamide groups. This study can provide insights for designing new nanomaterials that can efficiently remove radionuclides from radioactive wastewater.

  2. Partition functions and graphs: A combinatorial approach

    CERN Document Server

    Solomon, A I; Duchamp, G; Horzela, A; Penson, K A; Solomon, Allan I.; Blasiak, Pawel; Duchamp, Gerard; Horzela, Andrzej; Penson, Karol A.

    2004-01-01

    Although symmetry methods and analysis are a necessary ingredient in every physicist's toolkit, rather less use has been made of combinatorial methods. One exception is in the realm of Statistical Physics, where the calculation of the partition function, for example, is essentially a combinatorial problem. In this talk we shall show that one approach is via the normal ordering of the second quantized operators appearing in the partition function. This in turn leads to a combinatorial graphical description, giving essentially Feynman-type graphs associated with the theory. We illustrate this methodology by the explicit calculation of two model examples, the free boson gas and a superfluid boson model. We show how the calculation of partition functions can be facilitated by knowledge of the combinatorics of the boson normal ordering problem; this naturally gives rise to the Bell numbers of combinatorics. The associated graphical representation of these numbers gives a perturbation expansion in terms of a sequen...

  3. Density functional for van der Waals forces accounts for hydrogen bond in benchmark set of water hexamers

    DEFF Research Database (Denmark)

    Kelkkanen, Kari André; Lundqvist, Bengt; Nørskov, Jens Kehlet

    2009-01-01

    A recent extensive study has investigated how various exchange-correlation (XC) functionals treat hydrogen bonds in water hexamers and has shown traditional generalized gradient approximation and hybrid functionals used in density-functional (DF) theory to give the wrong dissociation-energy trend...

  4. Density Functional Studies of the C-F Bond Activation of CF3 Radical by Bare Co +

    Institute of Scientific and Technical Information of China (English)

    张冬菊; 刘成卜; 胡海泉; 刘永军

    2001-01-01

    The C—F bond activation mechanism of CF3 radical by bare Co + has been studied by density functional theory. Three local minima and two first-order saddle points were located for the potential energy surface (PES) of [Co, C, F3] + . The activation barrier involving C-F bond activation was calculated to be only 14.73 kJ/mol, while the largest barrier of 149.29 kJ/mol on the PES involves Co-C bond rupture.The bonding mechanism between Co + , C and F atoms were discussed based on Mulliken population. The relevant bond dissociation energy and thermochmistry data were calculated with the limited experimental values, and the results are in good agreement with the experimental findings.

  5. Hydrogen bonds in the nucleobase-gold complexes: Photoelectron spectroscopy and density functional calculations

    Science.gov (United States)

    Cao, Guo-Jin; Xu, Hong-Guang; Li, Ren-Zhong; Zheng, Weijun

    2012-01-01

    The nucleobase-gold complexes were studied with anion photoelectron spectroscopy and density functional calculations. The vertical detachment energies of uracil-Au-, thymine-Au-, cytosine-Au-, adenine-Au-, and guanine-Au- were estimated to be 3.37 ± 0.08 eV, 3.40 ± 0.08 eV, 3.23 ± 0.08 eV, 3.28 ± 0.08 eV, and 3.43 ± 0.08 eV, respectively, based on their photoelectron spectra. The combination of photoelectron spectroscopy experiments and density functional calculations reveals the presence of two or more isomers for these nucleobase-gold complexes. The major isomers detected in the experiments probably are formed by Au anion with the canonical tautomers of the nucleobases. The gold anion essentially interacts with the nucleobases through N-H...Au hydrogen bonds.

  6. Hydrogen-bonding interactions between a nitrile-based functional ionic liquid and DMSO

    Science.gov (United States)

    Zheng, Yan-Zhen; Zhou, Yu; Deng, Geng; Yu, Zhi-Wu

    2016-11-01

    Task-specific ionic liquids (TSILs) have been introduced by incorporating additional functional groups in the cation or anion to impart specific properties or reactivates. In this work, the hydrogen-bonding interactions between a nitrile-functional TSIL 1-propylnitrile-3-methylimidazolium tetrafluoroborate ([PCNMIM][BF4]) and dimethyl sulphoxide (DMSO) were investigated in detail by attenuated total reflection infrared spectroscopy (ATR-IR), combined with hydrogen nuclear magnetic resonance (1H NMR) and density functional theory calculations (DFT). It was found that, first, introducing a nitrile group into the alkyl chain does not change the main interaction site in the cation. It is still the C2 hydrogen. So the v(C2-H) is more sensitive to the environmental change and can be used as an indicator of the environments change of IL. Second, the wavenumber shift changes of v(C2-H) have two turning points (xDMSO ≈ 0.6 and 0.9), dividing the dilution process into three stages. Combined with the calculation results, the dilution process is identified as: From larger ion clusters to smaller ion clusters (xDMSO 0.9). Introducing a nitrile group into the alkyl chain does not influence the dilution process of IL dissolving in DMSO. Third, the Ctbnd N in [PCNMIM][BF4] can work as an electron donor in forming hydrogen-bonds with the methyl group of [PCNMIM]+ and DMSO, but its strength is weaker than that formed by the imidazolium ring C-Hs. The dual roles of the cation to work as both electron acceptor and donor expand the wide applications of this nitrile-functional ionic liquid.

  7. Investigation of structure and hydrogen bonding of superhydrous phase B (HT) under pressure using first-principles density functional calculations

    Science.gov (United States)

    Poswal, H. K.; Sharma, Surinder M.; Sikka, S. K.

    2010-03-01

    High-pressure behaviour of superhydrous phase B (high temperature; HT) of Mg10Si3O14(OH)4 (Shy B) is investigated with the help of density functional theory-based first-principles calculations. In addition to the lattice parameters and equation of state, we use these calculations to determine the positional parameters of atoms as a function of pressure. Our results show that the compression induced structural changes involve cooperative distortions in the full geometry of the hydrogen bonds. The bond-bending mechanism proposed by Hofmeister et al. (Vibrational spectra of dense hydrous magnesium silicates at high pressure: Importance of the hydrogen bond angle, Am. Miner. 84 (1999), pp. 454-464) for hydrogen bonds to relieve the heightened repulsion due to short H- - -H contacts is not found to be effective in Shy B. The calculated O-H bond contraction is consistent with the observed blue shift in the stretching frequency of the hydrogen bond. These results establish that one can use first-principles calculations to obtain reliable insights into the pressure-induced bonding changes of complex minerals.

  8. Covalent functionalization of graphene by azobenzene with molecular hydrogen bonds for long-term solar thermal storage

    OpenAIRE

    Feng, Yiyu; Liu, Hongpo; Luo, Wen; Liu, Enzuo; Zhao, Naiqin; Yoshino, Katsumi; Feng, Wei

    2013-01-01

    Reduced graphene oxide-azobenzene (RGO-AZO) hybrids were prepared via covalent functionalization for long-term solar thermal storage. Thermal barrier (ΔEa ) of cis to tran reversion and thermal storage (ΔH) were improved by molecular hydrogen bonds (H-bonds) through ortho- or para-substitution of AZO. Intramolecular H-bonds thermally stabilized cis-ortho-AZO on RGO with a long-term half-life of 5400 h (ΔEa = 1.2 eV), which was much longer than that of RGO-para-AZO (116 h). RGO-para-AZO with o...

  9. Recent advances in C(sp3)–H bond functionalization via metal–carbene insertions

    Science.gov (United States)

    Wang, Bo; Qiu, Di; Zhang, Yan

    2016-01-01

    Summary The recent development of intermolecular C–H insertion in the application of C(sp3)–H bond functionalizations, especially for light alkanes, is reviewed. The challenging problem of regioselectivity in C–H bond insertions has been tackled by the use of sterically bulky metal catalysts, such as metal porphyrins and silver(I) complexes. In some cases, high regioselectivity and enantioselectivity have been achieved in the C–H bond insertion of small alkanes. This review highlights the most recent accomplishments in this field. PMID:27340470

  10. Trends in bond dissociation energies of alcohols and aldehydes computed with multireference averaged coupled-pair functional theory.

    Science.gov (United States)

    Oyeyemi, Victor B; Keith, John A; Carter, Emily A

    2014-05-01

    As part of our ongoing investigation of the combustion chemistry of oxygenated molecules using multireference correlated wave function methods, we report bond dissociation energies (BDEs) in C1-C4 alcohols (from methanol to the four isomers of butanol) and C1-C4 aldehydes (from methanal to butanal). The BDEs are calculated with a multireference averaged coupled-pair functional-based scheme. We compare these multireference BDEs with those derived from experiment and single-reference methods. Trends in BDEs for the alcohols and aldehydes are rationalized by considering geometry relaxations of dissociated radical fragments, resonance stabilization, and hyperconjugation. Lastly, we discuss the conjectured association between bond strengths and rates of hydrogen abstraction by hydroxyl radicals. In general, abstraction reaction rates are higher at sites where the C-H bond energies are lower (and vice versa). However, comparison with available rate data shows this inverse relationship between bond strengths and abstraction rates does not hold at all temperatures.

  11. Dynamic Analysis and Design Optimization of Series Hydraulic Hybrid System through Power Bond Graph Approach

    Directory of Open Access Journals (Sweden)

    R. Ramakrishnan

    2014-01-01

    Full Text Available The availability of natural gas and crude oil resources has been declining over the years. In automobile sector, the consumption of crude oil is 63% of total crude oil production in the world. Hence, automobile industries are placing more emphasis on energy efficient hydraulic hybrid systems, which can replace their conventional transmission systems. Series hydraulic hybrid system (SHHS is a multidomain mechatronics system with two distinct power sources that includes prime mover and hydropneumatic accumulator. It replaces the conventional transmission system to drive the vehicle. The sizing of the subsystems in SHHS plays a major role in improving the energy efficiency of the vehicle. In this paper, a power bond graph approach is used to model the dynamics of the SHHS. The obtained simulation results indicate the energy flow during various modes of operations. It also includes the dynamic response of hydropneumatic accumulator, prime mover, and system output speed. Further, design optimization of the system is carried out to optimize the process parameters for maximizing the system energy efficiency. This leads to increase in fuel economy and environmentally friendly vehicle.

  12. Flexural and tensile bond strength, related via a stochastic numerical approach

    NARCIS (Netherlands)

    Pluijm, R. van der

    1998-01-01

    The flexural strength of masonry parallel to the bed joint depends on the geometry of the cross section, tensile bond strength, fracture energy, stiffness of units and of mortar joints. In experiments, tensile bond strength and fracture energy determined on relatively small specimens, show a large s

  13. Parental Bonding

    Directory of Open Access Journals (Sweden)

    T. Paul de Cock

    2014-08-01

    Full Text Available Estimating the early parent–child bonding relationship can be valuable in research and practice. Retrospective dimensional measures of parental bonding provide a means for assessing the experience of the early parent–child relationship. However, combinations of dimensional scores may provide information that is not readily captured with a dimensional approach. This study was designed to assess the presence of homogeneous groups in the population with similar profiles on parental bonding dimensions. Using a short version of the Parental Bonding Instrument (PBI, three parental bonding dimensions (care, authoritarianism, and overprotection were used to assess the presence of unobserved groups in the population using latent profile analysis. The class solutions were regressed on 23 covariates (demographics, parental psychopathology, loss events, and childhood contextual factors to assess the validity of the class solution. The results indicated four distinct profiles of parental bonding for fathers as well as mothers. Parental bonding profiles were significantly associated with a broad range of covariates. This person-centered approach to parental bonding has broad utility in future research which takes into account the effect of parent–child bonding, especially with regard to “affectionless control” style parenting.

  14. The Bond Order of C2 from a Strictly N-Representable Natural Orbital Energy Functional Perspective.

    Science.gov (United States)

    Piris, Mario; Lopez, Xabier; Ugalde, Jesus M

    2016-03-14

    The bond order of the ground electronic state of the carbon dimer has been analyzed in the light of natural orbital functional theory calculations carried out with an approximate, albeit strictly N-representable, energy functional. Three distinct solutions have been found from the Euler equations of the minimization of the energy functional with respect to the natural orbitals and their occupation numbers, which expand upon increasing values of the internuclear coordinate. In the close vicinity of the minimum energy region, two of the solutions compete around a discontinuity point. The former, corresponding to the absolute minimum energy, features two valence natural orbitals of each of the following symmetries, σ, σ*, π and π*, and has three bonding interactions and one antibonding interaction, which is very suggestive of a bond order large than two but smaller than three. The latter, features one σ-σ* linked pair of natural orbitals and three degenerate pseudo-bonding like orbitals, paired each with one triply degenerate pseudo-antibonding orbital, which points to a bond order larger than three. When correlation effects, other than Hartree-Fock for example, between the paired natural orbitals are accounted for, this second solution vanishes yielding a smooth continuous dissociation curve. Comparison of the vibrational energies and electron ionization energies, calculated on this curve, with their corresponding experimental marks, lend further support to a bond order for C2 intermediate between acetylene and ethylene.

  15. The Bond Order of C2 from a Strictly N-Representable Natural Orbital Energy Functional Perspective.

    Science.gov (United States)

    Piris, Mario; Lopez, Xabier; Ugalde, Jesus M

    2016-03-14

    The bond order of the ground electronic state of the carbon dimer has been analyzed in the light of natural orbital functional theory calculations carried out with an approximate, albeit strictly N-representable, energy functional. Three distinct solutions have been found from the Euler equations of the minimization of the energy functional with respect to the natural orbitals and their occupation numbers, which expand upon increasing values of the internuclear coordinate. In the close vicinity of the minimum energy region, two of the solutions compete around a discontinuity point. The former, corresponding to the absolute minimum energy, features two valence natural orbitals of each of the following symmetries, σ, σ*, π and π*, and has three bonding interactions and one antibonding interaction, which is very suggestive of a bond order large than two but smaller than three. The latter, features one σ-σ* linked pair of natural orbitals and three degenerate pseudo-bonding like orbitals, paired each with one triply degenerate pseudo-antibonding orbital, which points to a bond order larger than three. When correlation effects, other than Hartree-Fock for example, between the paired natural orbitals are accounted for, this second solution vanishes yielding a smooth continuous dissociation curve. Comparison of the vibrational energies and electron ionization energies, calculated on this curve, with their corresponding experimental marks, lend further support to a bond order for C2 intermediate between acetylene and ethylene. PMID:26822104

  16. Functional approaches in translation studies in Germany Functional approaches in translation studies in Germany

    OpenAIRE

    Paul Kussmaul

    2008-01-01

    In the early phase of translation studies in Germany, contrastive linguistics played a major role. I shall briefly describe this approach so that the functional approach will become clearer by contrast. Influenced by the representatives of stylistique comparée, Vinay/Darbelnet (1968) Wolfram Wilss, for instance, in his early work (1971, 1977) makes frequent use of the notion transposition (German “Ausdrucksverschiebung“, cf. also Catford’s (1965) term shift). As a whole, of course, Wilss...

  17. CRACK PROPAGATING IN FUNCTIONALLY GRADED COATING WITH ARBITRARILY DISTRIBUTED MATERIAL PROPERTIES BONDED TO HOMOGENEOUS SUBSTRATE

    Institute of Scientific and Technical Information of China (English)

    Zhanqi Cheng; Danying Gao; Zheng Zhong

    2010-01-01

    In this paper,a finite crack with constant length(Yoffe type crack)propagating in a functionally graded coating with spatially varying elastic properties bonded to a homoge-neous substrate of finite thickness under anti-plane loading was studied.A multi-layered model is employed to model arbitrary variations of material properties based on two linearly-distributed material compliance parameters.The mixed boundary problem is reduced to a system of singular integral equations that are solved numerically.Some numerical examples are given to demonstrate the accuracy,efficiency and versatility of the model.The numerical results show that the graded parameters,the thicknesses of the interracial layer and the two homogeneous layers,the crack size and speed have significant effects on the dynamic fracture behavior.

  18. Wafer-level packaging and laser bonding as an approach for silicon-into-lab-on-chip integration

    Science.gov (United States)

    Brettschneider, T.; Dorrer, C.; Bründel, M.; Zengerle, R.; Daub, M.

    2013-05-01

    A novel approach for the integration of silicon biosensors into microfluidics is presented. Our approach is based on wafer-level packaging of the silicon die and a laser-bonding process of the resulting mold package into a polymer-multilayer stack. The introduction of a flexible and 40 μm thin hot melt foil as an intermediate layer enables laser bonding between materials with different melting temperatures, where standard laser welding processes cannot be employed. All process steps are suitable for mass production, e.g. the approach does not involve any dispensing steps for glue or underfiller. The integration approach was demonstrated and evaluated regarding process technology by wafer-level redistribution of daisy chain silicon dies representing a generic biosensor. Electrical connection was successfully established and laser-bonding tensile strength of 5.7 N mm-2 and burst pressure of 587 kPa at a temperature of 100 °C were achieved for the new material combination. The feasibility of the complete packaging approach was shown by the fabrication of a microfluidic flow cell with embedded mold package.

  19. Approach to ''Mind'' using functional neuroimaging

    International Nuclear Information System (INIS)

    This review mainly describes authors' recent investigations concerning neuroimages approaching to even human ''mind'' using techniques of PET, SPECT and functional MRI (fMRI). Progress of such studies greatly owes to the development of image statistics of the brain like statistical parametric mapping (www.fil.ion.ucl.ac.uk/spm/), and brain standards (www.mrc-cbu.cam.ac.uk/Imaging/mnispace.html, and ric.uthscsa.edu/projects/talairach daemon.html). The author discusses and presents images in cases of hallucinations (SPECT and H215O-PET), autism (SPECT), sleep, depression, and its therapy by transcaranial magnetic stimulation. These studies are expected to contribute to diagnosis and therapy of endogenous neurological disorders. (T.I.)

  20. Quantum anharmonic oscillator: The airy function approach

    Energy Technology Data Exchange (ETDEWEB)

    Maiz, F., E-mail: fethimaiz@gmail.com [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia); University of Cartage, Nabeul Engineering Preparatory Institute, Merazka, 8000 Nabeul (Tunisia); AlFaify, S. [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia)

    2014-05-15

    New and simple numerical method is being reported to solve anharmonic oscillator problems. The method is setup to approach the real potential V(x) of the anharmonic oscillator system as a piecewise linear potential u(x) and to solve the Schrödinger equation of the system using the Airy function. Then, solutions continuity conditions lead to the energy quantification condition, and consequently, the energy eigenvalues. For testing purpose, the method was applied on the sextic and octic oscillators systems. The proposed method is found to be realistic, computationally simple, and having high degrees of accuracy. In addition, it can be applied to any form of potential. The results obtained by the proposed method were seen closely agreeing with results reached by other complicated methods.

  1. Adaptive Shape Functions and Internal Mesh Adaptation for Modelling Progressive Failure in Adhesively Bonded Joints

    Science.gov (United States)

    Stapleton, Scott; Gries, Thomas; Waas, Anthony M.; Pineda, Evan J.

    2014-01-01

    Enhanced finite elements are elements with an embedded analytical solution that can capture detailed local fields, enabling more efficient, mesh independent finite element analysis. The shape functions are determined based on the analytical model rather than prescribed. This method was applied to adhesively bonded joints to model joint behavior with one element through the thickness. This study demonstrates two methods of maintaining the fidelity of such elements during adhesive non-linearity and cracking without increasing the mesh needed for an accurate solution. The first method uses adaptive shape functions, where the shape functions are recalculated at each load step based on the softening of the adhesive. The second method is internal mesh adaption, where cracking of the adhesive within an element is captured by further discretizing the element internally to represent the partially cracked geometry. By keeping mesh adaptations within an element, a finer mesh can be used during the analysis without affecting the global finite element model mesh. Examples are shown which highlight when each method is most effective in reducing the number of elements needed to capture adhesive nonlinearity and cracking. These methods are validated against analogous finite element models utilizing cohesive zone elements.

  2. Direct Functionalization of Nitrogen Heterocycles via Rh-Catalyzed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Jared; Bergman, Robert; Ellman, Jonathan

    2008-02-04

    Nitrogen heterocycles are present in many compounds of enormous practical importance, ranging from pharmaceutical agents and biological probes to electroactive materials. Direct funtionalization of nitrogen heterocycles through C-H bond activation constitutes a powerful means of regioselectively introducing a variety of substituents with diverse functional groups onto the heterocycle scaffold. Working together, our two groups have developed a family of Rh-catalyzed heterocycle alkylation and arylation reactions that are notable for their high level of functional-group compatibility. This Account describes their work in this area, emphasizing the relevant mechanistic insights that enabled synthetic advances and distinguished the resulting transformations from other methods. They initially discovered an intramolecular Rh-catalyzed C-2-alkylation of azoles by alkenyl groups. That reaction provided access to a number of di-, tri-, and tetracyclic azole derivatives. They then developed conditions that exploited microwave heating to expedite these reactions. While investigating the mechanism of this transformation, they discovered that a novel substrate-derived Rh-N-heterocyclic carbene (NHC) complex was involved as an intermediate. They then synthesized analogous Rh-NHC complexes directly by treating precursors to the intermediate [RhCl(PCy{sub 3}){sub 2}] with N-methylbenzimidazole, 3-methyl-3,4-dihydroquinazolein, and 1-methyl-1,4-benzodiazepine-2-one. Extensive kinetic analysis and DFT calculations supported a mechanism for carbene formation in which the catalytically active RhCl(PCy{sub 3}){sub 2} fragment coordinates to the heterocycle before intramolecular activation of the C-H bond occurs. The resulting Rh-H intermediate ultimately tautomerizes to the observed carbene complex. With this mechanistic information and the discovery that acid co-catalysts accelerate the alkylation, they developed conditions that efficiently and intermolecularly alkylate a variety of

  3. Bond graph to digraph conversion: A sensor placement optimization for fault detection and isolation by a structural approach

    Indian Academy of Sciences (India)

    Alem Saïd; Benazzouz Djamel

    2014-10-01

    In this paper, we consider the optimal sensors placement problem for faults detection and isolation using a novel structural and qualitative approach. This approach is based on the conversion of Bond Graph to Digraph representation of a structural system. When the fault detection and isolation of an existing system’s sensors are impossible or uncertain, a reconfiguration sensor placement of this system should be reconsidered. This paper proposes how this reconfiguration takes place by recovering all missing or redundant parts of the system. This novel approach is illustrated over a thermo-fluid application.

  4. Interface of covalently bonded phospholipids with a phosphorylcholine head: characterization, protein nonadsorption, and further functionalization.

    Science.gov (United States)

    Ferez, Lynda; Thami, Thierry; Akpalo, Edefia; Flaud, Valérie; Tauk, Lara; Janot, Jean-Marc; Déjardin, Philippe

    2011-09-20

    Surface anchored poly(methylhydrosiloxane) (PMHS) thin films on oxidized silicon wafers or glass substrates were functionalized via the SiH hydrosilylation reaction with the internal double bonds of 1,2-dilinoleoyl-sn-glycero-3-phosphorylcholine (18:2 Cis). The surface was characterized by X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, and scanning electron microscopy. These studies showed that the PMHS top layer could be efficiently modified resulting in an interfacial high density of phospholipids. Grafted phospholipids made the initially hydrophobic surface (θ = 106°) very hydrophilic and repellent toward avidin, bovine serum albumin, bovine fibrinogen, lysozyme, and α-chymotrypsin adsorption in phosphate saline buffer pH 7.4. The surface may constitute a new background-stable support with increased biocompatibility. Further possibilities of functionalization on the surface remain available owing to the formation of interfacial SiOH groups by Karstedt-catalyzed side reactions of SiH groups with water. The presence of interfacial SiOH groups was shown by zeta potential measurements. The reactivity and surface density of SiOH groups were checked by fluorescence after reaction of a monoethoxy silane coupling agent bearing Alexa as fluorescent probe.

  5. Communication: Bond length alternation of conjugated oligomers: Another step on the fifth rung of Perdew's ladder of functional

    Science.gov (United States)

    Chabbal, Sylvain; Jacquemin, Denis; Adamo, Carlo; Stoll, Hermann; Leininger, Thierry

    2010-10-01

    In this work, we present the application of the hybrid short-range density functional theory/long-range MP2 energy gradients to the bond length alternation in polymethineimine and polyacetylene conjugated oligomers. Compared to other density functional calculations, our results are quite superior, even to fourth rung functionals, usually better than MP2 and very close to the available CCSD(T) values.

  6. Soil eukaryotic functional diversity, a metatranscriptomic approach.

    Science.gov (United States)

    Bailly, Julie; Fraissinet-Tachet, Laurence; Verner, Marie-Christine; Debaud, Jean-Claude; Lemaire, Marc; Wésolowski-Louvel, Micheline; Marmeisse, Roland

    2007-11-01

    To appreciate the functional diversity of communities of soil eukaryotic micro-organisms we evaluated an experimental approach based on the construction and screening of a cDNA library using polyadenylated mRNA extracted from a forest soil. Such a library contains genes that are expressed by each of the different organisms forming the community and represents its metatranscriptome. The diversity of the organisms that contributed to this library was evaluated by sequencing a portion of the 18S rDNA gene amplified from either soil DNA or reverse-transcribed RNA. More than 70% of the sequences were from fungi and unicellular eukaryotes (protists) while the other most represented group was the metazoa. Calculation of richness estimators suggested that more than 180 species could be present in the soil samples studied. Sequencing of 119 cDNA identified genes with no homologues in databases (32%) and genes coding proteins involved in different biochemical and cellular processes. Surprisingly, the taxonomic distribution of the cDNA and of the 18S rDNA genes did not coincide, with a marked under-representation of the protists among the cDNA. Specific genes from such an environmental cDNA library could be isolated by expression in a heterologous microbial host, Saccharomyces cerevisiae. This is illustrated by the functional complementation of a histidine auxotrophic yeast mutant by two cDNA originating possibly from an ascomycete and a basidiomycete fungal species. Study of the metatranscriptome has the potential to uncover adaptations of whole microbial communities to local environmental conditions. It also gives access to an abundant source of genes of biotechnological interest.

  7. Efficient Synthesis of Functionalized Benzimidazoles and Perimidines: Ytterbium Chloride Catalyzed CmC Bond Cleavage%Efficient Synthesis of Functionalized Benzimidazoles and Perimidines: Ytterbium Chloride Catalyzed CmC Bond Cleavage

    Institute of Scientific and Technical Information of China (English)

    Cai, Lijian; Ji, Xiaofeng; Yao, Zhigang; Xu, Fan; Shen, Qi

    2011-01-01

    An efficient method is developed for the synthesis of functionalized benzimidazoles and perimidines by the condensation of aryl diamines with β-carbonyl compounds catalyzed by ytterbium chloride. The reactions give good yields under mild conditions. A mechanism involving a lanthanide activated C--C bond cleavage is proposed.

  8. Density functional theory, natural bond orbital and quantum theory of atoms in molecule analyses on the hydrogen bonding interactions in tryptophan-water complexes

    Indian Academy of Sciences (India)

    Xiqian Niu; Zhengguo Huang; Lingling Ma; Tingting Shen; Lingfei Guo

    2013-07-01

    The tryptophan-water (Trp-H2O) complexes formed by hydrogen bonding interactions were investigated at the B97XD/6-311++G(d,p) level. Five Trp-H2O complexes possessing various types of hydrogen bonds (H-bonds) were characterized by geometries, energies, vibrational frequencies. The nature of the H-bonds were characterized by the natural bond orbital (NBO) and the quantum theory of atoms in molecule (QTAIM) analyses as well. The intramolecular H-bond formed between the amino and carboxyl oxygen atom of tryptophan was retained in most of the complexes, and the cooperativity between the intra and intermolecular H-bonds exist in some complexes. The intramolecular H-bond and some intermolecular H-bonds are strong and have partial covalent character. The H-bonds formed between carboxyl and oxygen/nitrogen atoms are stronger than other H-bonds. The H-bonds involving methylene of tryptophan as H-donor are weak H-bonds. For all complexes,ele and ex makes major contributions to the total interaction energy (MP2), while disp is the smallest component of the interaction energy. Both hydrogen bonding interaction and structural deformation play important roles in the relative stabilities of the complexes. Regardless of strong H-bonds, the stabilities of some complexes are weakened by the serious structural deformations.

  9. Thermoplasmonics modeling: A Green's function approach

    Science.gov (United States)

    Baffou, Guillaume; Quidant, Romain; Girard, Christian

    2010-10-01

    We extend the discrete dipole approximation (DDA) and the Green’s dyadic tensor (GDT) methods—previously dedicated to all-optical simulations—to investigate the thermodynamics of illuminated plasmonic nanostructures. This extension is based on the use of the thermal Green’s function and a original algorithm that we named Laplace matrix inversion. It allows for the computation of the steady-state temperature distribution throughout plasmonic systems. This hybrid photothermal numerical method is suited to investigate arbitrarily complex structures. It can take into account the presence of a dielectric planar substrate and is simple to implement in any DDA or GDT code. Using this numerical framework, different applications are discussed such as thermal collective effects in nanoparticles assembly, the influence of a substrate on the temperature distribution and the heat generation in a plasmonic nanoantenna. This numerical approach appears particularly suited for new applications in physics, chemistry, and biology such as plasmon-induced nanochemistry and catalysis, nanofluidics, photothermal cancer therapy, or phase-transition control at the nanoscale.

  10. Cation-interlinking network cluster approach in application to extended defects in covalent-bonded glassy semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shpotyuk, Oleh [Lviv Institute of Materials of SRC, Lviv (Ukraine); Institute of Physics, Jan Dlugosz University, Czestochowa (Poland); Boyko, Vitaliy [Lviv Institute of Materials of SRC, Lviv (Ukraine); Lviv Polytechnic National University (Ukraine); Hyla, Malgorzata [Institute of Physics, Jan Dlugosz University, Czestochowa (Poland)

    2009-08-15

    A principally new cation-interlinking network cluster approach (CINCA) was proposed to describe different types of glass-forming structural units in network covalent-bonded solids like to chalcogenide vitreous semiconductors. Within this approach, two (or three) interconnected cation-centered polyhedra form more stretched structural fragments conditionally named atomic clusters, reflecting in such a way whole backbone of covalent-bonded semiconductor multiply duplicated in a space. The probability of possible atomic clusters is estimated with numerical parameter giving average formation energy in respect to the number of atoms involved in the cluster and average coordination number. This approach was probed at the example of regular network clusters based on AsS{sub 3/2} pyramids mutually-interconnected through bridge -S- atom contrasted with irregular double-bond-based quasi-tetrahedral structural S=AsS{sub 3} defects within binary As-S system. The corresponding mathematical calculations confirming a preference of regularly-linked structural units over irregular ones was performed using HyperChem 7.5 program. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Novel electrochemical approach to study corrosion mechanism of Al-Au wire-bond pad interconnections

    DEFF Research Database (Denmark)

    Elisseeva, O. V.; Bruhn, A.; Cerezo, J.;

    2013-01-01

    A gold-aluminium material combination is typically employed as an interconnection for microelectronic devices. One of the reliability risks of such devices is that of corrosion of aluminium bond pads resulting from the galvanic coupling between an aluminium bond pad and a gold wire. The research...... gold films were applied on Ti-Al covered silicon surfaces, and their morphology and electrochemical behaviour were analysed using the localised electrochemical cell, scanning vibrating electrode technique, scanning electron microscopy-energy dispersive X-ray spectroscopy, scanning electron microscopy...

  12. Correlation hole effect in comblike copolymer systems obtained by hydrogen bonding between homopolymers and end-functionalized oligomers

    NARCIS (Netherlands)

    Huh, J; Ikkala, O; tenBrinke, G

    1997-01-01

    This paper addresses concentration fluctuations in comblike copolymer systems obtained by hydrogen bonding between polymers and end-functionalized oligomers. Monodisperse block copolymer systems in the homogeneous melt exhibit small-angle X-ray scattering peaks at finite nonzero angle due to charact

  13. Graphene Oxide Catalyzed C-H Bond Activation: The Importance Oxygen Functional Groups for Biaryl Construction

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Yongjun; Tang, Pei; Zhou, Hu; Zhang, Wei; Yang, Hanjun; Yan, Ning; Hu, Gang; Mei, Donghai; Wang, Jianguo; Ma, Ding

    2016-02-24

    A heterogeneous, inexpensive and environment-friendly carbon catalytic system was developed for the C-H bond arylation of benzene resulting in the subsequent formation of biaryl compounds. The oxygen-containing groups on these graphene oxide sheets play an essential role in the observed catalytic activity. The catalytic results of model compounds and DFT calculations show that these functional groups promote this reaction by stabilization and activation of K ions at the same time of facilitating the leaving of I. And further mechanisms studies show that it is the charge induced capabilities of oxygen groups connected to specific carbon skeleton together with the giant π-reaction platform provided by the π-domain of graphene that played the vital roles in the observed excellent catalytic activity. D. Mei acknowledges the support from the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory.

  14. The Trouble with Chemical Energy: Why Understanding Bond Energies Requires an Interdisciplinary Systems Approach

    Science.gov (United States)

    Cooper, Melanie M.; Klymkowsky, Michael W.

    2013-01-01

    Helping students understand "chemical energy" is notoriously difficult. Many hold inconsistent ideas about what energy is, how and why it changes during the course of a chemical reaction, and how these changes are related to bond energies and reaction dynamics. There are (at least) three major sources for this problem: 1) the way biologists talk…

  15. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals

    Science.gov (United States)

    Wyrick, Jonathan; Einstein, T. L.; Bartels, Ludwig

    2015-03-01

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species' diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system.

  16. Chemical insight from density functional modeling of molecular adsorption: Tracking the bonding and diffusion of anthracene derivatives on Cu(111) with molecular orbitals

    Energy Technology Data Exchange (ETDEWEB)

    Wyrick, Jonathan; Bartels, Ludwig, E-mail: ludwig.bartels@ucr.edu [Pierce Hall, University of California-Riverside, Riverside, California 92521 (United States); Einstein, T. L. [Department of Physics and Condensed Matter Theory Center, University of Maryland, College Park, Maryland 20742-4111 (United States)

    2015-03-14

    We present a method of analyzing the results of density functional modeling of molecular adsorption in terms of an analogue of molecular orbitals. This approach permits intuitive chemical insight into the adsorption process. Applied to a set of anthracene derivates (anthracene, 9,10-anthraquinone, 9,10-dithioanthracene, and 9,10-diselenonanthracene), we follow the electronic states of the molecules that are involved in the bonding process and correlate them to both the molecular adsorption geometry and the species’ diffusive behavior. We additionally provide computational code to easily repeat this analysis on any system.

  17. Extraction of consensus protein patterns in regions containing non-proline cis peptide bonds and their functional assessment

    Directory of Open Access Journals (Sweden)

    Rigas Georgios

    2011-05-01

    Full Text Available Abstract Background In peptides and proteins, only a small percentile of peptide bonds adopts the cis configuration. Especially in the case of amide peptide bonds, the amount of cis conformations is quite limited thus hampering systematic studies, until recently. However, lately the emerging population of databases with more 3D structures of proteins has produced a considerable number of sequences containing non-proline cis formations (cis-nonPro. Results In our work, we extract regular expression-type patterns that are descriptive of regions surrounding the cis-nonPro formations. For this purpose, three types of pattern discovery are performed: i exact pattern discovery, ii pattern discovery using a chemical equivalency set, and iii pattern discovery using a structural equivalency set. Afterwards, using each pattern as predicate, we search the Eukaryotic Linear Motif (ELM resource to identify potential functional implications of regions with cis-nonPro peptide bonds. The patterns extracted from each type of pattern discovery are further employed, in order to formulate a pattern-based classifier, which is used to discriminate between cis-nonPro and trans-nonPro formations. Conclusions In terms of functional implications, we observe a significant association of cis-nonPro peptide bonds towards ligand/binding functionalities. As for the pattern-based classification scheme, the highest results were obtained using the structural equivalency set, which yielded 70% accuracy, 77% sensitivity and 63% specificity.

  18. Theoretical Study of the N-NO2 Bond Dissociation Energies for Energetic Materials with Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Hong; TANG Zheng-Xin; Abraham F.Jalbout; ZHANG Xian-Zhou; CHENG Xin-Lu

    2008-01-01

    The N-NO2 bond dissociation energies (BDEs) for 7 energetic materials were computed by means of accurate density functional theory (B3LYP, B3PW91 and B3P86) with 6-31G** and 6-311G** basis sets. By comparing the computed energies and experimental results, we find that the B3P86/6-311G** method can give good results of BDE, which has the mean absolute deviation of 1.30 kcal/mol. In addition, substituent effects were also taken into account. It is noted that the Hammett constants of substituent groups are related to the BDEs of the N-NO2 bond and the bond dissociation energies of the energetic materials studied decrease when increasing the number of NO2 group.

  19. Bonding to dentin as a function of air-stream temperatures for solvent evaporation

    Directory of Open Access Journals (Sweden)

    Andréia Aquino Marsiglio

    2012-06-01

    Full Text Available This study evaluated the influence of solvent evaporation conditions of acid-etching adhesives. The medium dentin of thirty extracted human third molars was exposed and bonded to different types of etch-and-rinse adhesives: 1 Scotchbond Multi-Purpose (SBMP ; water-based; 2 Adper Single Bond 2 (SB ; ethanol/water-based, and 3 Prime & Bond 2.1 (PB ; acetone-based. Solvents were evaporated at air-drying temperatures of 21ºC or 38ºC. Composite buildups were incrementally constructed. After storage in water for 24 h at 37ºC, the specimens were prepared for bond strength testing. Data were analyzed by two-way ANOVA and Tukey's test (5%. SBMP performed better when the solvents were evaporated at a higher temperature (p < 0.05. Higher temperatures did not affect the performance of SB or PB. Bond strength at room temperature was material-dependent, and air-drying temperatures affected bonding of the water-based, acid-etching adhesive.

  20. Functional approaches in translation studies in Germany Functional approaches in translation studies in Germany

    Directory of Open Access Journals (Sweden)

    Paul Kussmaul

    2008-04-01

    Full Text Available In the early phase of translation studies in Germany, contrastive linguistics played a major role. I shall briefly describe this approach so that the functional approach will become clearer by contrast. Influenced by the representatives of stylistique comparée, Vinay/Darbelnet (1968 Wolfram Wilss, for instance, in his early work (1971, 1977 makes frequent use of the notion transposition (German “Ausdrucksverschiebung“, cf. also Catford’s (1965 term shift. As a whole, of course, Wilss’ work has a much broader scope. More recently, he has investigated the role of cognition (1988 and the various factors in translator behaviour (1996. Nevertheless, transposition is still a very important and useful notion in describing the translation process. The need for transpositions arises when there is no possibility of formal one-to-one correspondence between source and target-language structures. The basic idea is that whenever there is a need for transposition, we are faced with a translation problem. In the early phase of translation studies in Germany, contrastive linguistics played a major role. I shall briefly describe this approach so that the functional approach will become clearer by contrast. Influenced by the representatives of stylistique comparée, Vinay/Darbelnet (1968 Wolfram Wilss, for instance, in his early work (1971, 1977 makes frequent use of the notion transposition (German “Ausdrucksverschiebung“, cf. also Catford’s (1965 term shift. As a whole, of course, Wilss’ work has a much broader scope. More recently, he has investigated the role of cognition (1988 and the various factors in translator behaviour (1996. Nevertheless, transposition is still a very important and useful notion in describing the translation process. The need for transpositions arises when there is no possibility of formal one-to-one correspondence between source and target-language structures. The basic idea is that whenever there is a need for

  1. Density Functional Approach Based on Numerically Obtained Bridge Functional

    Institute of Scientific and Technical Information of China (English)

    ZHOUShi-Qi

    2002-01-01

    The ornstein-zenike equation is solved with the Rogers-Young approximation for bulk hard sphere fluid and Lennard-Jones fluid for several state points.Then the resulted bulk fluid radial distribution function combined with the test particle method is employed to determine numerically the function relationship of bridge functional as a function of indirect correlation function.It is found that all of the calculated points from different phase space state points for a same type of fluid collapse onto a same smooth curve.Then the numerically obtained curve is used to substitute the analytic expression of the bridge functional as a function of indirect correlation function required in the methodology [J.Chem.Phys,112(2000)8079] to determine the density distribution of non-uniform hard sphere fluid and Lennard-Jones fluid.The good agreement of theoretical predictions with the computer simulation data is obtained.The present numerical procedure incroporates the knowledge of bulk fluid radial distribution function into the constructing of the density functional approximation and makes the original methodology more accurate and more filexible for various interaction potential fluid.

  2. Detection of discriminative sequence patterns in the neighborhood of proline cis peptide bonds and their functional annotation

    Directory of Open Access Journals (Sweden)

    Papaloukas Costas

    2009-04-01

    Full Text Available Abstract Background Polypeptides are composed of amino acids covalently bonded via a peptide bond. The majority of peptide bonds in proteins is found to occur in the trans conformation. In spite of their infrequent occurrence, cis peptide bonds play a key role in the protein structure and function, as well as in many significant biological processes. Results We perform a systematic analysis of regions in protein sequences that contain a proline cis peptide bond in order to discover non-random associations between the primary sequence and the nature of proline cis/trans isomerization. For this purpose an efficient pattern discovery algorithm is employed which discovers regular expression-type patterns that are overrepresented (i.e. appear frequently repeated in a set of sequences. Four types of pattern discovery are performed: i exact pattern discovery, ii pattern discovery using a chemical equivalency set, iii pattern discovery using a structural equivalency set and iv pattern discovery using certain amino acids' physicochemical properties. The extracted patterns are carefully validated using a specially implemented scoring function and a significance measure (i.e. log-probability estimate indicative of their specificity. The score threshold for the first three types of pattern discovery is 0.90 while for the last type of pattern discovery 0.80. Regarding the significance measure, all patterns yielded values in the range [-9, -31] which ensure that the derived patterns are highly unlikely to have emerged by chance. Among the highest scoring patterns, most of them are consistent with previous investigations concerning the neighborhood of cis proline peptide bonds, and many new ones are identified. Finally, the extracted patterns are systematically compared against the PROSITE database, in order to gain insight into the functional implications of cis prolyl bonds. Conclusion Cis patterns with matches in the PROSITE database fell mostly into two

  3. Density Functional Approach Based on Numerically Obtained Bridge Functional

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shi-Qi

    2002-01-01

    The Ornstein Zernike equation is solved with the Rogers Young approximation for bulk hard sphere fluidand Lennard-Jones fluid for several state points. Then the resulted bulk fluid radial distribution function combinedwith the test particle method is employed to determine numerically the function relationship of bridge functional as afunction of indirect correlation function. It is found that all of the calculated points from different phase space statepoints for a same type of fluid collapse onto a same smooth curve. Then the numerically obtained curve is used tosubstitute the analytic expression of the bridge functional as a function of indirect correlation function required in themethodology [J. Chem. Phys. 112 (2000) 8079] to deterrnine the density distribution of non-uniform hard spherefluid and Lennard Jones fluid. The good agreement of theoretical predictions with the computer simulation data isobtained. The present numerical procedure incorporates the knowledge of bulk fluid radial distribution function intothe constructing of the density functional approximation and makes the original methodology more accurate and moreflexible for various interaction potential fluid.

  4. A Functional Analytic Approach to Group Psychotherapy

    Science.gov (United States)

    Vandenberghe, Luc

    2009-01-01

    This article provides a particular view on the use of Functional Analytical Psychotherapy (FAP) in a group therapy format. This view is based on the author's experiences as a supervisor of Functional Analytical Psychotherapy Groups, including groups for women with depression and groups for chronic pain patients. The contexts in which this approach…

  5. Hydrogen bonding strength of diblock copolymers affects the self-assembled structures with octa-functionalized phenol POSS nanoparticles.

    Science.gov (United States)

    Lu, Yi-Syuan; Yu, Chia-Yu; Lin, Yung-Chih; Kuo, Shiao-Wei

    2016-02-28

    In this study, the influence of the functional groups by the diblock copolymers of poly(styrene-b-4-vinylpyridine) (PS-b-P4VP), poly(styrene-b-2-vinylpyridine) (PS-b-P2VP), and poly(styrene-b-methyl methacrylate) (PS-b-PMMA) on their blends with octa-functionalized phenol polyhedral oligomeric silsesquioxane (OP-POSS) nanoparticles (NPs) was investigated. The relative hydrogen bonding strengths in these blends follow the order PS-b-P4VP/OP-POSS > PS-b-P2VP/OP-POSS > PS-b-PMMA/OP-POSS based on the Kwei equation from differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopic analyses. Small-angle X-ray scattering and transmission electron microscopic analyses show that the morphologies of the self-assembly structures are strongly dependent on the hydrogen bonding strength at relatively higher OP-POSS content. The PS-b-P4VP/OP-POSS hybrid complex system with the strongest hydrogen bonds shows the order-order transition from lamellae to cylinders and finally to body-centered cubic spheres upon increasing OP-POSS content. However, PS-b-P2VP/OP-POSS and PS-b-PMMA/OP-POSS hybrid complex systems, having relatively weaker hydrogen bonds, transformed from lamellae to cylinder structures at lower OP-POSS content (50 wt%). PMID:26781581

  6. Quantum Confinement in Hydrogen Bond

    CERN Document Server

    Santos, Carlos da Silva dos; Ricotta, Regina Maria

    2015-01-01

    In this work, the quantum confinement effect is proposed as the cause of the displacement of the vibrational spectrum of molecular groups that involve hydrogen bonds. In this approach the hydrogen bond imposes a space barrier to hydrogen and constrains its oscillatory motion. We studied the vibrational transitions through the Morse potential, for the NH and OH molecular groups inside macromolecules in situation of confinement (when hydrogen bonding is formed) and non-confinement (when there is no hydrogen bonding). The energies were obtained through the variational method with the trial wave functions obtained from Supersymmetric Quantum Mechanics (SQM) formalism. The results indicate that it is possible to distinguish the emission peaks related to the existence of the hydrogen bonds. These analytical results were satisfactorily compared with experimental results obtained from infrared spectroscopy.

  7. A computational approach for the annotation of hydrogen-bonded base interactions in crystallographic structures of the ribozymes

    Energy Technology Data Exchange (ETDEWEB)

    Hamdani, Hazrina Yusof, E-mail: hazrina@mfrlab.org [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi (Malaysia); Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Kepala Batas (Malaysia); Artymiuk, Peter J., E-mail: p.artymiuk@sheffield.ac.uk [Dept. of Molecular Biology and Biotechnology, Firth Court, University of Sheffield, S10 T2N Sheffield (United Kingdom); Firdaus-Raih, Mohd, E-mail: firdaus@mfrlab.org [School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi (Malaysia)

    2015-09-25

    A fundamental understanding of the atomic level interactions in ribonucleic acid (RNA) and how they contribute towards RNA architecture is an important knowledge platform to develop through the discovery of motifs from simple arrangements base pairs, to more complex arrangements such as triples and larger patterns involving non-standard interactions. The network of hydrogen bond interactions is important in connecting bases to form potential tertiary motifs. Therefore, there is an urgent need for the development of automated methods for annotating RNA 3D structures based on hydrogen bond interactions. COnnection tables Graphs for Nucleic ACids (COGNAC) is automated annotation system using graph theoretical approaches that has been developed for the identification of RNA 3D motifs. This program searches for patterns in the unbroken networks of hydrogen bonds for RNA structures and capable of annotating base pairs and higher-order base interactions, which ranges from triples to sextuples. COGNAC was able to discover 22 out of 32 quadruples occurrences of the Haloarcula marismortui large ribosomal subunit (PDB ID: 1FFK) and two out of three occurrences of quintuple interaction reported by the non-canonical interactions in RNA (NCIR) database. These and several other interactions of interest will be discussed in this paper. These examples demonstrate that the COGNAC program can serve as an automated annotation system that can be used to annotate conserved base-base interactions and could be added as additional information to established RNA secondary structure prediction methods.

  8. A computational approach for the annotation of hydrogen-bonded base interactions in crystallographic structures of the ribozymes

    Science.gov (United States)

    Hamdani, Hazrina Yusof; Artymiuk, Peter J.; Firdaus-Raih, Mohd

    2015-09-01

    A fundamental understanding of the atomic level interactions in ribonucleic acid (RNA) and how they contribute towards RNA architecture is an important knowledge platform to develop through the discovery of motifs from simple arrangements base pairs, to more complex arrangements such as triples and larger patterns involving non-standard interactions. The network of hydrogen bond interactions is important in connecting bases to form potential tertiary motifs. Therefore, there is an urgent need for the development of automated methods for annotating RNA 3D structures based on hydrogen bond interactions. COnnection tables Graphs for Nucleic ACids (COGNAC) is automated annotation system using graph theoretical approaches that has been developed for the identification of RNA 3D motifs. This program searches for patterns in the unbroken networks of hydrogen bonds for RNA structures and capable of annotating base pairs and higher-order base interactions, which ranges from triples to sextuples. COGNAC was able to discover 22 out of 32 quadruples occurrences of the Haloarcula marismortui large ribosomal subunit (PDB ID: 1FFK) and two out of three occurrences of quintuple interaction reported by the non-canonical interactions in RNA (NCIR) database. These and several other interactions of interest will be discussed in this paper. These examples demonstrate that the COGNAC program can serve as an automated annotation system that can be used to annotate conserved base-base interactions and could be added as additional information to established RNA secondary structure prediction methods.

  9. Multiconfigurational Green's function approaches in quantum chemistry

    International Nuclear Information System (INIS)

    The author discusses multiconfigurational Green's function techniques and generalizations. In particular he is interested in developing and applying these techniques for isolated atoms and small molecules. Furthermore, he develops formalisms that are fairly clear, accurate, and capable of being applied to open-shell and highly-correlated systems as well as to closed-shell systems with little electronic correlation. The two kinds of Green's functions that this article discusses are the single-particle Green's function and the retarded two-time Green's function in the energy representation. The poles of the former give the ionization potentials and electron affinities while the poles of the latter give the excitation energies. The multiconfigurational approximations are known as the multiconfigurational electron propagator (MCEP) and the multiconfigurational time-dependent Hartree-Fock (MCTDHF) (also known as the multiconfigurational random phase approximation (MCRPA) or the multiconfigurational linear response), respectively. 44 references

  10. A Multivariate Approach to Functional Neuro Modeling

    DEFF Research Database (Denmark)

    Mørch, Niels J.S.

    1998-01-01

    , provides the basis for a generalization theoretical framework relating model performance to model complexity and dataset size. Briefly summarized the major topics discussed in the thesis include: - An introduction of the representation of functional datasets by pairs of neuronal activity patterns...... a generalization theoretical framework centered around measures of model generalization error. - Only few, if any, examples of the application of generalization theory to functional neuro modeling currently exist in the literature. - Exemplification of the proposed generalization theoretical framework...... as particularly important; optimal model flexibility is a function of both the complexity and the size of the dataset at hand. This is something that has not received appropriate attention by the functional neuro modeling community so far. The observation implies that optimal model performance rarely is achieved...

  11. Optimal sensors placement for monitoring a steam condenser of the distillation column using bond graph approach

    Directory of Open Access Journals (Sweden)

    Samia LATRECHE

    2014-11-01

    Full Text Available This paper deals with monitoring of a process engineering system. The steam condenser was monitored by bond graph tool. The model was constituted by nine capacitive and resistive elements which needed minimum of sensors. This method was based on Analytical Redundancy Relations which were generated from a condenser model and represented residuals. After substitution, we obtained the placement of six sensors which guaranteed the monitoring of nine components. A fault is created by the abrupt annulment of the fluid flow value provided by the source. The block diagram is elaborated on SYMBOLS software and we supervised the residuals evolution.

  12. Dentin Bonding Testing Using a Mini-interfacial Fracture Toughness Approach.

    Science.gov (United States)

    Pongprueksa, P; De Munck, J; Karunratanakul, K; Barreto, B C; Van Ende, A; Senawongse, P; Van Meerbeek, B

    2016-03-01

    Measurement of interfacial fracture toughness (iFT) is considered a more valid method to assess bonding effectiveness as compared with conventional bond strength testing. Common fracture toughness tests are, however, laborious and require a relatively bulky specimen size. This study aimed to evaluate a new simplified and miniaturized iFT (mini-iFT) test. Four dentin adhesives, representing the main adhesive classes, and 1 glass ionomer cement were applied onto flat dentin. Mini-iFT (1.5 × 2.0 × 16 to 18 mm) and microtensile bond strength (µTBS; 1.5 × 1.5 × 16 to 18 mm) specimens were prepared from the same tooth. For the mini-iFT specimens, a single notch was cut at the adhesive-dentin interface with a 150-µm diamond blade under water cooling; the specimens were loaded until failure in a 4-point bending test setup. Finite element analysis was used to analyze stress distribution during mini-iFT testing. The correlation between the mean mini-iFT and µTBS was examined and found to be significant; a strong positive correlation was found (r(2) = 0.94, P = 0.004). Weibull data analysis suggested the mini-iFT to vary less than the µTBS. Both the mini-iFT and the µTBS revealed the same performance order, with the 3-step etch-and-rinse adhesive outperforming the 2-step self-etch and 2-step etch-and-rinse adhesive, followed by the 1-step SE adhesive and, finally, the glass ionomer cement. Scanning electron microscopy failure analysis revealed the adhesive-dentin interface to fail more at the actual interface with the mini-iFT test, while µTBS specimens failed more within dentin and composite. This finding was corroborated by finite element analysis showing stress to concentrate at the interface during mini-iFT loading and crack propagation. In conclusion, the new mini-iFT test appeared more discriminative and valid than the µTBS to assess bonding effectiveness; the latter test nevertheless remains more versatile. Specimen size and workload were alike, making the

  13. On Bond Portfolio Management

    OpenAIRE

    Vladislav Kargin

    2002-01-01

    This paper describes a new method of bond portfolio optimization based on stochastic string models of correlation structure in bond returns. The paper shows how to approximate correlation function of bond returns, compute the optimal portfolio allocation using Wiener-Hopf factorization, and check whether a collection of bonds presents arbitrage opportunities.

  14. Four Layered Approach to Non-Functional Requirements Analysis

    CERN Document Server

    Rao, A Ananda

    2012-01-01

    Identification of non-functional requirements is important for successful development and deployment of the software product. The acceptance of the software product by the customer depends on the non-functional requirements which are incorporated in the software. For this, we need to identify all the non-functional requirements required by all stakeholders. In the literature not many approaches are available for this purpose. Hence, we have proposed a four layered analysis approach for identification of non-functional requirements. The proposed layered approach has many advantages over non-layered approach. As part of this approach some rules are also proposed to be used in each layer. The approach is applied successfully on two case studies. The identified non-functional requirements are validated using a check list and in addition the completeness of the identified non-requirements is computed using a metric.

  15. Direct space decomposition of ELI-D: interplay of charge density and pair-volume function for different bonding situations.

    Science.gov (United States)

    Wagner, Frank R; Kohout, Miroslav; Grin, Yuri

    2008-10-01

    The topological features, i.e., gradients and curvatures of the same-spin electron pair restricted electron localizability indicator (ELI-D) in position space are analyzed in terms of those of the electron density and the pair-volume function. The analysis of the topology of these constituent functions and their interplay on ELI-D attractor formation for a number of molecules representing chemically different bonding situations allows distinguishing between different chemical bonding scenarios on a quantum mechanical basis without the recourse to orbitals. The occurrence of the Laplacian of the electron density in the expression for the Laplacian of ELI-D allows us to establish a physical link between electron localizability and electron pairing as displayed by ELI-D and the role of Laplacian of the density in this context.

  16. A simple and surprisingly accurate approach to the chemical bond obtained from dimensional scaling

    CERN Document Server

    Svidzinsky, A A; Scully, M O

    2005-01-01

    We present a new dimensional scaling transformation of the Schrodinger equation for the two electron bond. This yields, for the first time, a good description of the two electron bond via D-scaling. There also emerges, in the large-D limit, an intuitively appealing semiclassical picture, akin to a molecular model proposed by Niels Bohr in 1913. In this limit, the electrons are confined to specific orbits in the scaled space, yet the uncertainty principle is maintained because the scaling leaves invariant the position-momentum commutator. A first-order perturbation correction, proportional to 1/D, substantially improves the agreement with the exact ground state potential energy curve. The present treatment is very simple mathematically, yet provides a strikingly accurate description of the potential energy curves for the lowest singlet, triplet and excited states of H_2. We find the modified D-scaling method also gives good results for other molecules. It can be combined advantageously with Hartree-Fock and ot...

  17. Functional renormalization group approach to neutron matter

    Directory of Open Access Journals (Sweden)

    Matthias Drews

    2014-11-01

    Full Text Available The chiral nucleon-meson model, previously applied to systems with equal number of neutrons and protons, is extended to asymmetric nuclear matter. Fluctuations are included in the framework of the functional renormalization group. The equation of state for pure neutron matter is studied and compared to recent advanced many-body calculations. The chiral condensate in neutron matter is computed as a function of baryon density. It is found that, once fluctuations are incorporated, the chiral restoration transition for pure neutron matter is shifted to high densities, much beyond three times the density of normal nuclear matter.

  18. Genomic and functional approaches to genetic adaptation

    OpenAIRE

    Carnero-Montoro, Elena

    2013-01-01

    The genetic basis of phenotypes that have contributed to the adaptation of species and organisms to new environments is a central question in evolutionary genetics. The recent accumulation of genetic variability data has allowed a genome-wide search for different signatures of positive selection which has led to the discovery of hundreds of putative candidate genes that may have played a role in adaptation. However, such hypothesis-free approaches do not reveal either causal va...

  19. Energy Density Functional Approach to Superfluid Nuclei

    OpenAIRE

    Yu, Yongle; Bulgac, Aurel

    2002-01-01

    We show that within the framework of a simple local nuclear energy density functional (EDF), one can describe accurately the one-- and two--nucleon separation energies of semi--magic nuclei. While for the normal part of the EDF we use previously suggested parameterizations, for the superfluid part of the EDF we use the simplest possible local form compatible with known nuclear symmetries.

  20. Density Functional Theory Approach to Nuclear Fission

    CERN Document Server

    Schunck, N

    2012-01-01

    The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.

  1. Effect of self-interaction error in the evaluation of the bond length alternation in trans-polyacetylene using density-functional theory

    Science.gov (United States)

    Ciofini, I.; Adamo, C.; Chermette, H.

    2005-09-01

    The calculation of the bond-length alternation (BLA) in trans-polyacetylene has been chosen as benchmark to emphasize the effect of the self-interaction error within density-functional theory (DFT). In particular, the BLA of increasingly long acetylene oligomers has been computed using the Møller-Plesset wave-function method truncated at the second order and several DFT models. While local-density approximation (LDA) or generalized gradient corrected (GGA) functionals strongly underestimate the BLA, approaches including self-interaction corrections (SIC) provide significant improvements. Indeed, the simple averaged-density SIC scheme (ADSIC), recently proposed by Legrand et al. [J. Phys. B 35, 1115 (2002)], provides better results for the structure of large oligomers than the more complex approach of Krieger et al. [Phys. Rev. A 45, 101 (1992)]. The ADSIC method is particularly promising since both the exchange-correlation energy and potential are improved with respect to standard LDA/GGA using a physically appealing correction, through a different route than the more popular approach through the Hartree-Fock exchange inclusion within the hybrid functionals.

  2. Compact two-electron wave function for bond dissociation and Van der Waals interactions: A natural amplitude assessment

    International Nuclear Information System (INIS)

    Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions, and near degeneracy static correlations. In this work, we analyze for a one-dimensional model of a two-electron system how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function f (r12) depending on the interelectronic distance r12. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems, we make an analysis of the wave function in terms of the NO amplitudes for a model system of a diatomic molecule. In our numerical implementation, we fully optimize the orbitals and the correlation function on a spatial grid without restrictions on their functional form. Due to this particular form of the wave function, we can prove that none of the amplitudes vanishes and moreover that it displays a distinct sign pattern and a series of avoided crossings as a function of the bond distance in agreement with the exact solution. This shows that the wave function ansatz correctly incorporates the long range Van der Waals interactions. We further show that the approximate wave function gives an excellent binding curve and is able to describe static correlations. We show that in order to do this the correlation function f (r12) needs to diverge for large r12 at large internuclear distances while for shorter bond distances it increases as a function of r12 to a maximum value after which it decays exponentially. We further give a physical interpretation of this behavior

  3. Realistic Representation of Grain Shapes in CFD--DEM Simulations of Sediment Transport: A Bonded-Sphere Approach

    CERN Document Server

    Sun, Rui

    2016-01-01

    Development of algorithms and growth of computational resources in the past decades have enabled simulations of sediment transport processes with unprecedented fidelities. The Computational Fluid Dynamics--Discrete Element Method (CFD--DEM) is one of the high-fidelity approaches, where the motions of and collisions among the sediment grains as well as their interactions with surrounding fluids are resolved. In most DEM solvers the particles are modeled as soft spheres due to computational efficiency and implementation complexity considerations, although natural sediments are usually mixture of non-spherical particles. Previous attempts to extend sphere-based DEM to treat irregular particles neglected fluid-induced torques on particles, and the method lacked flexibility to handle sediments with an arbitrary mixture of particle shapes. In this contribution we proposed a simple, efficient approach to represent common sediment grain shapes with bonded spheres, where the fluid forces are computed and applied on ea...

  4. Proton conductivity in quasi-one dimensional hydrogen-bonded systems: A nonlinear approach

    International Nuclear Information System (INIS)

    Defect formation and transport in a hydrogen-bonded system is studied via a two-sublattice soliton-bearing one-dimensional model. Ionic and orientational defects are associated with distinct nonlinear topological excitations in the present model. The dynamics of these excitations is studied both analytically and with the use of numerical simulations. It is shown that the two types of defects are soliton solutions of a double Sine--Gordon equation which describes the motion of the protons in the long-wavelength limit. With each defect there is an associated deformation in the ionic lattice that, for small speeds, follows the defect dynamically albeit resisting its motion. Free propagation as well as collision properties of the proton solitons are presented. 33 refs., 10 figs

  5. Cohesive Laws and Progressive Damage Analysis of Composite Bonded Joints, a Combined Numerical/Experimental Approach

    Science.gov (United States)

    Girolamo, Donato; Davila, Carlos G.; Leone, Frank A.; Lin, Shih-Yung

    2015-01-01

    The results of an experimental/numerical campaign aimed to develop progressive damage analysis (PDA) tools for predicting the strength of a composite bonded joint under tensile loads are presented. The PDA is based on continuum damage mechanics (CDM) to account for intralaminar damage, and cohesive laws to account for interlaminar and adhesive damage. The adhesive response is characterized using standard fracture specimens and digital image correlation (DIC). The displacement fields measured by DIC are used to calculate the J-integrals, from which the associated cohesive laws of the structural adhesive can be derived. A finite element model of a sandwich conventional splice joint (CSJ) under tensile loads was developed. The simulations, in agreement with experimental tests, indicate that the model is capable of predicting the interactions of damage modes that lead to the failure of the joint.

  6. Bonding titanium on multi-walled carbon nanotubes for hydrogen storage: An electrochemical approach

    Energy Technology Data Exchange (ETDEWEB)

    Brieno-Enriquez, K.M.; Ledesma-Garcia, J. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S.C., Parque Tecnologico Queretaro-Sanfandila, Pedro Escobedo, Qro, C.P. 76703 (Mexico); Perez-Bueno, J.J., E-mail: jperez@cideteq.mx [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S.C., Parque Tecnologico Queretaro-Sanfandila, Pedro Escobedo, Qro, C.P. 76703 (Mexico); Godinez, Luis A. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, S.C., Parque Tecnologico Queretaro-Sanfandila, Pedro Escobedo, Qro, C.P. 76703 (Mexico); Terrones, H. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Division de Materiales Avanzados, Camino a la Presa San Jose 2055, Col. Lomas 4o Seccion C.P. 78216, San Luis Potosi (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, A.P. 14-805, 07730 Mexico D.F. (Mexico)

    2009-06-15

    This work explores the use of some procedures, involving electrochemistry, in order to bond atomic Ti on the outer surface of multi-walled carbon nanotubes (MWNTs). It is assumed that each titanium atom has the potential of host up to four hydrogen molecules and relinquish them by heated. As a way to spread and stick nanotubes on an electrode, a tested route was drying a solution with nanotubes on a glassy carbon flat electrode. The MWNTs were treated by anodic polarization in organic media. Dichloromethane was selected as the medium and titanium tetrachloride as the precursor for attaching atomic Ti onto the nanotubes. The hydrogen adsorption, estimated from voltamperometry was five times higher on Ti-MWNTs that on bare nanotubes. The use of anodic polarization during the preparation of Ti-MWNTs may represent great significance in procedure, which was manifest during the voltamperometric evaluation of samples.

  7. Functional genomics approach to hypoxia signaling.

    Science.gov (United States)

    Seta, Karen A; Millhorn, David E

    2004-02-01

    Mammalian cells require a constant supply of oxygen to maintain energy balance, and sustained hypoxia can result in cell death. It is therefore not surprising that sophisticated adaptive mechanisms have evolved that enhance cell survival during hypoxia. During the past few years, there have been a growing number of reports on hypoxia-induced transcription of specific genes. In this review, we describe a unique experimental approach that utilizes focused cDNA libraries coupled to microarray analyses to identify hypoxia-responsive signal transduction pathways and genes that confer the hypoxia-tolerant phenotype. We have used the subtractive suppression hybridization (SSH) method to create a cDNA library enriched in hypoxia-regulated genes in oxygen-sensing pheochromocytoma cells and have used this library to create microarrays that allow us to examine hundreds of genes at a time. This library contains over 300 genes and expressed sequence tags upregulated by hypoxia, including tyrosine hydroxylase, vascular endothelial growth factor, and junB. Hypoxic regulation of these and other genes in the library has been confirmed by microarray, Northern blot, and real-time PCR analyses. Coupling focused SSH libraries with microarray analyses allows one to specifically study genes relevant to a phenotype of interest while reducing much of the biological noise associated with these types of studies. When used in conjunction with high-throughput, dye-based assays for cell survival and apoptosis, this approach offers a rapid method for discovering validated therapeutic targets for the treatment of cardiovascular disease, stroke, and tumors. PMID:14715686

  8. An extrinsic function-level evolvable hardware approach

    OpenAIRE

    Kalganova, T

    2000-01-01

    The function level evolvable hardware approach to synthesize the combinational multiple-valued and binary logic functions is proposed in first time. The new representation of logic gate in extrinsic EHW allows us to describe behaviour of any multi-input multi-output logic function. The circuit is represented in the form of connections and functionalities of a rectangular array of building blocks. Each building block can implement primitive logic function or any multi-input multi-output log...

  9. Lyapunov Functions Family Approach to Transient Stability Assessment

    OpenAIRE

    Vu, Thanh Long; Turitsyn, Konstantin

    2014-01-01

    Analysis of transient stability of strongly nonlinear post-fault dynamics is one of the most computationally challenging parts of Dynamic Security Assessment. This paper proposes a novel approach for assessment of transient stability of the system. The approach generalizes the idea of energy methods, and extends the concept of energy function to a more general Lyapunov Functions Family (LFF) constructed via Semi-Definite-Programming techniques. Unlike the traditional energy function and its v...

  10. A new approach to bootstrap inference in functional coefficient models

    OpenAIRE

    Herwartz, Helmut; Xu, Fang

    2007-01-01

    We introduce a new, factor based bootstrap approach which is robust under heteroskedastic error terms for inference in functional coefficient models. Modeling the functional coefficient parametrically, the bootstrap approximation of an F statistic is shown to hold asymptotically. In simulation studies with both parametric and nonparametric functional coefficients, factor based bootstrap inference outperforms the wild bootstrap and pairs bootstrap approach according to its size features. Apply...

  11. Mechatronics by bond graphs an object-oriented approach to modelling and simulation

    CERN Document Server

    Damić, Vjekoslav

    2015-01-01

    This book presents a computer-aided approach to the design of mechatronic systems. Its subject is an integrated modeling and simulation in a visual computer environment. Since the first edition, the simulation software changed enormously, became more user-friendly and easier to use. Therefore, a second edition became necessary taking these improvements into account. The modeling is based on system top-down and bottom-up approach. The mathematical models are generated in a form of differential-algebraic equations and solved using numerical and symbolic algebra methods. The integrated approach developed is applied to mechanical, electrical and control systems, multibody dynamics, and continuous systems. .

  12. X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

    2006-09-27

    Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

  13. An estimating function approach to linkage heterogeneity

    Indian Academy of Sciences (India)

    He Gao; Ying Zhou; Weijun Ma; Haidong Liu; Linan Zhao

    2013-12-01

    Testing linkage heterogeneity between two loci is an important issue in genetics. Currently, there are four methods (K-test, A-test, B-test and D-test) for testing linkage heterogeneity in linkage analysis, which are based on the likelihood-ratio test. Among them, the commonly used methods are the K-test and A-test. In this paper, we present a novel test method which is different from the above four tests, called G-test. The new test statistic is based on estimating function, possessing a theoretic asymptotic distribution, and therefore demonstrates its own advantages. The proposed test is applied to analyse a real pedigree dataset. Our simulation results also indicate that the G-test performs well in terms of power of testing linkage heterogeneity and outperforms the current methods to some degree.

  14. Organic chemistry. Functionalization of C(sp3)-H bonds using a transient directing group.

    Science.gov (United States)

    Zhang, Fang-Lin; Hong, Kai; Li, Tuan-Jie; Park, Hojoon; Yu, Jin-Quan

    2016-01-15

    Proximity-driven metalation has been extensively exploited to achieve reactivity and selectivity in carbon-hydrogen (C-H) bond activation. Despite the substantial improvement in developing more efficient and practical directing groups, their stoichiometric installation and removal limit efficiency and, often, applicability as well. Here we report the development of an amino acid reagent that reversibly reacts with aldehydes and ketones in situ via imine formation to serve as a transient directing group for activation of inert C-H bonds. Arylation of a wide range of aldehydes and ketones at the β or γ positions proceeds in the presence of a palladium catalyst and a catalytic amount of amino acid. The feasibility of achieving enantioselective C-H activation reactions using a chiral amino acid as the transient directing group is also demonstrated.

  15. Spectroscopically determined force field for water dimer: physically enhanced treatment of hydrogen bonding in molecular mechanics energy functions.

    Science.gov (United States)

    Mannfors, Berit; Palmo, Kim; Krimm, Samuel

    2008-12-11

    Our ab initio transformed spectroscopically determined force field (SDFF) methodology emphasizes, in addition to accurate structure and energy performance, comparable prediction of vibrational properties in order to improve reproduction of interaction forces. It is now applied to the determination of a molecular mechanics (MM) force field for the water monomer and dimer as an initial step in developing a more physically based treatment of the hydrogen bonding that not only underlies condensed-phase water but also must be important in molecular-level protein-water interactions. Essential electrical components of the SDFF for monomer water are found to be the following: an off-plane charge distribution, this distribution consisting of four off-atom charge sites in traditional lone pair (LP) but also in inverted lone pair (ILP) positions; allowance for a diffuse size to these off-atom sites; and the incorporation of charge fluxes (i.e., the change in charge with change in internal coordinate). Parametrization of such an LP/ILP model together with the SDFF analytically transformed valence force field results in essentially exact agreement with ab initio (in this case MP2/6-31++G(d,p)) structure, electrical, and vibrational properties. Although we demonstrate that the properties of this monomer electrical model together with its van der Waals and polarization interactions are transferable to the dimer, this is not sufficient in reproducing comparable dimer properties, most notably the huge increase in infrared intensity of a donor OH stretch mode. This deficiency, which can be eliminated by a large dipole-derivative-determined change in the effective charge flux of the donor hydrogen-bonded OH bond, is not accounted for by the charge flux change in this bond due to the induction effects of the acceptor electric field alone, and can only be fully removed by an added bond flux associated with the extent of overlap of the wave functions of the two molecules. We show that

  16. The Microstructure and Chemical Bonds of β-C2S Under the High Energy Ball Grinding Function

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Using the laser granularity survey technology, X- ray powder diffraction, scanning electron mi croscopy (SEM) and infrared spectrum analysis methods, we studied the microscopic structure and chemical bonds changes of β- C2 S monomineral under the high energy ball grinding function .The result indicates that, continuously under the mechanical power, β-C2 S crystal size would decrease, the micro strain and the effective Beff parameter would increase, and the amorphous phases would be presented. Furthermore, the mechanical power would cause Si- O bond broken and reorganized, the specific surface area would increase, the energy of micro-pow der agglomeration vibration would be enhanced and the crystal would be disordered .Finally, β- C2 S was caused to have the mechanochemical change and the activity enhancement.

  17. The synthesis of functionalized bridged polycycles via C–H bond insertion

    Science.gov (United States)

    Shih, Jiun-Le; Chen, Po-An

    2016-01-01

    Summary This review presents examples from the chemical literature of syntheses of bridged-polycyclic products via C–H bond insertion by carbenes and nitrenes. Applications to natural product synthesis, a description of the essential elements in substrate-controlled reactions, and mechanistic details of transformations are presented. Overall, these transformations allow the construction of important ring systems rapidly and efficiently, though additional catalyst development is needed. PMID:27340489

  18. 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 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.

  19. Revisiting the European sovereign bonds with a permutation-information-theory approach

    Science.gov (United States)

    Fernández Bariviera, Aurelio; Zunino, Luciano; Guercio, María Belén; Martinez, Lisana B.; Rosso, Osvaldo A.

    2013-12-01

    In this paper we study the evolution of the informational efficiency in its weak form for seventeen European sovereign bonds time series. We aim to assess the impact of two specific economic situations in the hypothetical random behavior of these time series: the establishment of a common currency and a wide and deep financial crisis. In order to evaluate the informational efficiency we use permutation quantifiers derived from information theory. Specifically, time series are ranked according to two metrics that measure the intrinsic structure of their correlations: permutation entropy and permutation statistical complexity. These measures provide the rectangular coordinates of the complexity-entropy causality plane; the planar location of the time series in this representation space reveals the degree of informational efficiency. According to our results, the currency union contributed to homogenize the stochastic characteristics of the time series and produced synchronization in the random behavior of them. Additionally, the 2008 financial crisis uncovered differences within the apparently homogeneous European sovereign markets and revealed country-specific characteristics that were partially hidden during the monetary union heyday.

  20. Conceptual modelling approach of mechanical products based on functional surface

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A modelling framework based on functional surface is presented to support conceptual design of mechanical products. The framework organizes product information in an abstract and multilevel manner. It consists of two mapping processes: function decomposition process and form reconstitution process. The steady mapping relationship from function to form (function-functional surface-form) is realized by taking functional surface as the middle layer. It farthest reduces the possibilities of combinatorial explosion that can occur during function decomposition and form reconstitution. Finally, CAD tools are developed and an auto-bender machine is applied to demonstrate the proposed approach.

  1. A probabilistic approach to delineating functional brain regions

    DEFF Research Database (Denmark)

    Kalbitzer, Jan; Svarer, Claus; Frokjaer, Vibe G;

    2009-01-01

    healthy subjects. The templates were subsequently included in the region sets used in a previously published automatic MRI-based approach to create an observer- and activity-independent probabilistic VOI map. The probabilistic map approach was tested in a different group of 10 subjects and compared......-independent, reliable approach to delineating regions that can be identified only by functional imaging, here exemplified by the raphe nuclei. This approach can be used in future studies to create functional VOI maps based on neuroreceptor fingerprints retrieved through in vivo brain imaging Udgivelsesdato: 2009/6...

  2. Defining mental disorder. Exploring the 'natural function' approach

    OpenAIRE

    Varga Somogy

    2011-01-01

    Abstract Due to several socio-political factors, to many psychiatrists only a strictly objective definition of mental disorder, free of value components, seems really acceptable. In this paper, I will explore a variant of such an objectivist approach to defining metal disorder, natural function objectivism. Proponents of this approach make recourse to the notion of natural function in order to reach a value-free definition of mental disorder. The exploration of Christopher Boorse's 'biostatis...

  3. Functional Approach to Classical Yang-Mills Theories

    CERN Document Server

    Carta, P

    2002-01-01

    Sometime ago it was shown that the operatorial approach to classical mechanics, pioneered in the 30's by Koopman and von Neumann, can have a functional version. In this talk we will extend this functional approach to the case of classical field theories and in particular to the Yang-Mills ones. We shall show that the issues of gauge-fixing and Faddeev-Popov determinant arise also in this classical formalism.

  4. Defining mental disorder. Exploring the 'natural function' approach

    Directory of Open Access Journals (Sweden)

    Varga Somogy

    2011-01-01

    Full Text Available Abstract Due to several socio-political factors, to many psychiatrists only a strictly objective definition of mental disorder, free of value components, seems really acceptable. In this paper, I will explore a variant of such an objectivist approach to defining metal disorder, natural function objectivism. Proponents of this approach make recourse to the notion of natural function in order to reach a value-free definition of mental disorder. The exploration of Christopher Boorse's 'biostatistical' account of natural function (1 will be followed an investigation of the 'hybrid naturalism' approach to natural functions by Jerome Wakefield (2. In the third part, I will explore two proposals that call into question the whole attempt to define mental disorder (3. I will conclude that while 'natural function objectivism' accounts fail to provide the backdrop for a reliable definition of mental disorder, there is no compelling reason to conclude that a definition cannot be achieved.

  5. Combining formal and functional approaches to topic structure

    NARCIS (Netherlands)

    Zellers, M.; Post, B.

    2012-01-01

    Fragmentation between formal and functional approaches to prosodic variation is an ongoing problem in linguistic research. In particular, the frameworks of the Phonetics of Talk-in-Interaction (PTI) and Empirical Phonology (EP) take very different theoretical and methodological approaches to this ki

  6. Dynamical potential approach to dissociation of H-C bond in HCO highly excited vibration

    Institute of Scientific and Technical Information of China (English)

    Fang Chao; Wu Guo-Zhen

    2009-01-01

    The highly excited vibrational levels of HCO in the electronic ground state, X1A', are employed to determine the coefficients of an algebraic Hamiltonian, by which the dynamical potential is derived and shown to be very useful for interpreting thc intramolecular vibrational relaxation (IVR) which operates via the HCO bending motion. The IVR inhibits the dissociation of H atom and enhances the stochastic degree of dynamical character. This approach is from a global viewpoint on a series of levels classified by the polyad number which is a constant of motion in a certain dynamical domain. In this way, the seemingly complicated level structure shows very regular picture, dynamically.

  7. Text Analysis: A Functional Linguistic Approach of News Introduction

    Institute of Scientific and Technical Information of China (English)

    刘锦凤

    2009-01-01

    The past several decades have witnessed a phenomenal growth in interest in text analysis, in which different kinds of approaches have been studied and applied in this field. This paper aims at analyzing the introduction of a cho-sen CNN News from a functional linguis.tic approach, which is mainly realized through cohesive means and textual infor-mation. The study shows that in written text, well-organized semantic cohesive means and textual information are of great significance for readers to follow the movement of an idea from one sentence to another. Therefore, functional approach plays a momentous role in the analysis of a text.

  8. Kabat's Surface Terms in the $\\zeta$-Function approach

    CERN Document Server

    Iellici, D; Iellici, Devis; Moretti, Valter

    1997-01-01

    The thermal partition functions of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local zeta-function approach. The relation with the surface terms previously obtained by D. Kabat is studied. The results are discussed in relation to the quantum corrections to the black hole entropy.

  9. Molecular dynamics simulations on pars intercerebralis major peptide-C (PMP-C) reveal the role of glycosylation and disulfide bonds in its enhanced structural stability and function.

    Science.gov (United States)

    Kaushik, Sandeep; Mohanty, Debasisa; Surolia, Avadhesha

    2012-01-01

    Fucosylation of Thr 9 in pars intercerebralis major peptide-C (PMP-C) enhances its structural stability and functional ability as a serine protease inhibitor. In order to understand the role of disulfide bonds and glycosylation on the structure and function of PMP-C, we have carried out multiple explicit solvent molecular dynamics (MD) simulations on fucosylated and non-fucosylated forms of PMP-C, both in the presence and absence of the disulfide bonds. Our simulations revealed that there were no significant structural changes in the native disulfide bonded forms of PMP-C due to fucosylation. On the other hand, the non-fucosylated form of PMP-C without disulfide bonds showed larger deviations from the starting structure than the fucosylated form. However, the structural deviations were restricted to the terminal regions while core β-sheet retained its hydrogen bonded structure even in absence of disulfide bonds as well as fucosylation. Interestingly, fucosylation of disulfide bonded native PMP-C led to a decreased thermal flexibility in the residue stretch 29-32 which is known to interact with the active site of the target proteases. Our analysis revealed that disulfide bonds covalently connect the residue stretch 29-32 to the central β-sheet of PMP-C and using a novel network of side chain interactions and disulfide bonds fucosylation at Thr 9 is altering the flexibility of the stretch 29-32 located at a distal site. Thus, our simulations explain for the first time, how presence of disulfide bonds between conserved cysteines and fucosylation enhance the function of PMP-C as a protease inhibitor.

  10. Binary and Ternary Heterometallic (La3+, Gd3+, Y3+–Eu3+ Functionalized SBA-15 Mesoporous Hybrids: Chemically Bonded Assembly and Photoluminescence

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2010-01-01

    Full Text Available Abstract A novel kind of organic–inorganic monomer SUASi has been achieved by modifying 5-sulfosalicylic acid (SUA with 3-aminopropyltrimethoxysilane (APS, subsequently binary and ternary Eu3+ mesoporous hybrid materials with 5-sulfosalicylic acid (SUA-functionalized SBA-15 and 1,10-phenanthroline (phen are synthesized by co-condensation of SUASi and TEOS in the presence of Eu3+ complex and Pluronic P123 as a template. Finally, luminescent hybrid mesoporous materials consisting of active rare earth ions (Eu3+—inert rare earth ions (Y3+, La3+, Gd3+ complex covalently bonded to the mesoporous materials network have been obtained via this sol–gel approach. The physical characterization and photoluminescence of all these resulting materials are studied in detail. Especially the luminescent behavior has been studied with the different ratios of Eu3+–(Y3+, La3+, Gd3+, which suggests that the existence of inert rare earth ions can enhance the luminescence intensity of Eu3+. This may be due to the intramolecular energy transfer between Y3+, La3+, Gd3+, and Eu3+ through the covalently bonded mesoporous framework.

  11. The bonding of heavy metals on nitric acid-etched coal fly ashes functionalized with 2-mercaptoethanol or thioglycolic acid

    International Nuclear Information System (INIS)

    Coal fly ash is a waste by-product of the coal fire industry, which generates many environmental problems. Alternative uses of this material would provide efficient solutions for this by-product. In this work, nitric acid-etched coal fly ash labelled with 2-mercaptoethanol or thioglycolic acid was assessed for retention of Al(III), As(III), Cu(II), Cd(II), Fe(III), Mn(II), Hg(II), Ni(II), Pb(II) and Zn(II) ions. The bonding characteristics between the organic compounds with the solid support, as well as with the metal ions, were evaluated using various surface analytical techniques. Visualization of the organically-functionalized coal fly ash particle was possible using scanning electron microscopy (SEM), while the elemental composition of the functionalized material, before and after retention of the metal ions, was obtained by energy dispersive (ED)-X ray spectrometry (XRS) and electrothermal atomic absorption spectrometry (ETAAS). Fourier transform infrared (FT-IR) spectrometry and Raman spectrometry were used to obtain information about the functional groups. It was found that some metal(oid) ions (As, Ni, Pb, Zn) were coordinated through the mercaptan group, while other metal(oid)s (Al, Cd, Cu, Fe, Hg, Mn) were apparently bonded to oxygen atoms. A low-cost and effective solid phase retention system for extraction of heavy metals from aqueous solutions was thus developed. - Graphical abstract: Nitric acid-etched coal fly ash labelled with 2-mercaptoethanol or thioglycolic acid was intended for the retention of heavy metals. The bonding characteristics between the organic compounds with the solid support, as well as with the metal ions, were evaluated using surface analytical techniques. - Highlights: • Coal fly ashes were organically-functionalized. • Organically-functionalized coal fly ashes were spectrometrically characterized. • Organically-functionalized coal fly ashes can be used as an effective solid sorbent for metal(oid)s. • This retention

  12. Benchmarking Density Functional Theory Approaches for the Description of Symmetry-Breaking in Long Polymethine Dyes

    KAUST Repository

    Gieseking, Rebecca L.

    2016-04-25

    Long polymethines are well-known experimentally to symmetry-break, which dramatically modifies their linear and nonlinear optical properties. Computational modeling could be very useful to provide insight into the symmetry-breaking process, which is not readily available experimentally; however, accurately predicting the crossover point from symmetric to symmetry-broken structures has proven challenging. Here, we benchmark the accuracy of several DFT approaches relative to CCSD(T) geometries. In particular, we compare analogous hybrid and long-range corrected (LRC) functionals to clearly show the influence of the functional exchange term. Although both hybrid and LRC functionals can be tuned to reproduce the CCSD(T) geometries, the LRC functionals are better performing at reproducing the geometry evolution with chain length and provide a finite upper limit for the gas-phase crossover point; these methods also provide good agreement with the experimental crossover points for more complex polymethines in polar solvents. Using an approach based on LRC functionals, a reduction in the crossover length is found with increasing medium dielectric constant, which is related to localization of the excess charge on the end groups. Symmetry-breaking is associated with the appearance of an imaginary frequency of b2 symmetry involving a large change in the degree of bond-length alternation. Examination of the IR spectra show that short, isolated streptocyanines have a mode at ~1200 cm-1 involving a large change in bond-length alternation; as the polymethine length or the medium dielectric increases, the frequency of this mode decreases before becoming imaginary at the crossover point.

  13. Oxidation of MCrAlY bonding layers of thermal insulation coatings as a function of production parameters and alloy composition

    International Nuclear Information System (INIS)

    The oxidation behaviour of intermediate or bonding layers on a given gas turbine material (IN 100) is reported. The layers were brought onto the base material by plasma arc spraying in free air or controlled atmosphere, and consisted of spray powders of different aluminium content (Co-31 Ni-21Cr8Al0.5Y; Co-33Ni-21Cr-16Al0.5Y; composite powder with a Ni-19 Cr alloy core and 6% Al cladding). These bonding layers received a ceramic cover (ZrO2 + 7% of Y2O3) to serve as a thermal insulation coating. The oxidation behaviour of the bonding layers were analysed as a function of different spray powders, spraying techniques, surface roughness of bonding layer, and thickness of insulation coating or bonding layer. (MM)

  14. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Bahk, Yeon Kyoung; He, Xu; Gitsis, Emmanouil; Kuo, Yu-Ying [ETH Zurich, Institute of Environmental Engineering (Switzerland); Kim, Nayoung [EMPA, Building Energy Materials and Components (Switzerland); Wang, Jing, E-mail: jing.wang@ifu.baug.ethz.ch [ETH Zurich, Institute of Environmental Engineering (Switzerland)

    2015-10-15

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH{sub 3}CO{sub 2}NH{sub 4}) and sodium acetate (CH{sub 3}CO{sub 2}Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example.

  15. Design of Au/SPIO composite nanoparticle for facile and biocompatible surface functionalization via Au-S bond

    Energy Technology Data Exchange (ETDEWEB)

    Seino, Satoshi, E-mail: seino@mit.eng.osaka-u.ac.jp; Shibata, Yujin; Yamanaka, Masayuki; Nakagawa, Takashi [Osaka University, Graduate School of Engineering (Japan); Mukai, Yohei; Nakagawa, Shinsaku [Osaka University, Graduate School of Pharmaceutical Sciences and Center for Advanced Medical Engineering and Informatics (Japan); Yamamoto, Takao A. [Osaka University, Graduate School of Engineering (Japan)

    2013-01-15

    Immobilization of Au nanoparticles on super-paramagnetic iron-oxide (SPIO) enables facile and biocompatible surface functionalization via Au-S bond. Au/SPIO composite nanoparticle is easily modified by thiol-modified polyethylene glycol (PEG-SH), and they are successfully applied on MR tumor imaging. However, its large hydrodynamic size ({approx}150 nm) still causes the accumulation to liver in vivo. In this study, we controlled the hydrodynamic size of Au/SPIO by testing different raw SPIOs and stabilizing polymers. As the best candidate, Au/Molday-ION which was synthesized from Molday-ION and polyvinyl alcohol comprised the hydrodynamic size of 56 nm. Moreover, PEGylated Au/Molday-ION showed excellent dispersibility in blood serum, with the hydrodynamic size of 65 nm. This surface functionalization strategy is effective for the constructions of magnetic nanocarriers for in vivo applications.

  16. The Variety of Carbon-Metal Bonds inside Cu-ZSM-5 Zeolites: A Density Functional Theory Study

    Directory of Open Access Journals (Sweden)

    Takashi Yumura

    2010-04-01

    Full Text Available Large-scale density functional theory calculations (DFT found various types of binding of an unsaturated hydrocarbon (C2H2 and C2H4 to a ZSM-5 zeolite extraframework copper cation. We employed the DFT calculations based on the B3LYP functional to obtain local minima of an unsaturated hydrocarbon adsorbed on one or two copper cations embedded inside ZSM-5, and then compared their stabilization energies. The DFT results show that the stabilization energies are strongly dependent on the copper coordination environment as well as configurations of two copper cations. Consequently, the inner copper-carbon bonds are influenced substantially by a nanometer-scale cavity of ZSM-5.

  17. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    International Nuclear Information System (INIS)

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH3CO2NH4) and sodium acetate (CH3CO2Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example

  18. Social Media’s Function in Organizations: A Functional Analysis Approach

    Directory of Open Access Journals (Sweden)

    Amy Reitz

    2012-12-01

    Full Text Available System theorists believe that organizations that function as an open system have a greater chance of survival than organizations that function as a closed system due to the exchange of inputs and outputs between the organization and its publics. Public relations researchers have proposed adopting a dialogic approach to public relations where interaction between the organization and its publics are mutual, which is the underpinning to an open systems approach. This paper posits that organizations can function within an open systems approach to public relations by employing social media. Adoption of a functional approach is a fruitful way to look at the social functions various social media serve in the system of organizations and their publics. Research has considered the gratifications publics receive from social media; however, limited research has considered what social media do for the organization-public relationship system. It has been argued that organizations also have psychological and social motivations; therefore, applying a functional analysis approach might be a good of way determining what functions social media serve in the organization-public relationship system. Four functions are proposed in which social media may serve the system: maintenance of organizational identity, opportunity to build relationships with publics, ability to control issues management, and the chance to promote social corporate responsibility. Understanding social media’s role in the system can help practitioners identify the functions that may contribute to an open systems approach to public relations and ultimately an organization’s survival.

  19. Thymine- and Adenine-Functionalized Polystyrene Form Self-Assembled Structures through Multiple Complementary Hydrogen Bonds

    Directory of Open Access Journals (Sweden)

    Yu-Shian Wu

    2014-06-01

    Full Text Available In this study, we investigated the self-assembly of two homopolymers of the same molecular weight, but containing complementary nucleobases. After employing nitroxide-mediated radical polymerization to synthesize poly(vinylbenzyl chloride, we converted the polymer into poly(vinylbenzyl azide through a reaction with NaN3 and then performed click chemistry with propargyl thymine and propargyl adenine to yield the homopolymers, poly(vinylbenzyl triazolylmethyl methylthymine (PVBT and poly(vinylbenzyl triazolylmethyl methyladenine (PVBA, respectively. This PVBT/PVBA blend system exhibited a single glass transition temperature over the entire range of compositions, indicative of a miscible phase arising from the formation of multiple strong complementary hydrogen bonds between the thymine and adenine groups of PVBT and PVBA, respectively; Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy confirmed the presence of these noncovalent interactions. In addition, dynamic rheology, dynamic light scattering and transmission electron microscopy provided evidence for the formation of supramolecular network structures in these binary PVBT/PVBA blend systems.

  20. Computational approaches for rational design of proteins with novel functionalities

    DEFF Research Database (Denmark)

    Tiwari, Manish Kumar; Singh, Ranjitha; Singh, Raushan Kumar;

    2012-01-01

    Proteins are the most multifaceted macromolecules in living systems and have various important functions, including structural, catalytic, sensory, and regulatory functions. Rational design of enzymes is a great challenge to our understanding of protein structure and physical chemistry and has...... exciting results. Developments in this field are already having a significant impact on biotechnology and chemical biology. The application of powerful computational methods for functional protein designing has recently succeeded at engineering target activities. Here, we review recently reported de novo...... functional proteins that were developed using various protein design approaches, including rational design, computational optimization, and selection from combinatorial libraries, highlighting recent advances and successes....

  1. Exact response functions within the time-dependent Gutzwiller approach

    Science.gov (United States)

    Bünemann, J.; Wasner, S.; Oelsen, E. v.; Seibold, G.

    2015-02-01

    We investigate the applicability of the two existing versions of a time-dependent Gutzwiller approach (TDGA) beyond the frequently used limit of infinite spatial dimensions. To this end, we study the two-particle response functions of a two-site Hubbard model where we can compare the exact results and those derived from the TDGA. It turns out that only the more recently introduced version of the TDGA can be combined with a diagrammatic approach which allows for the evaluation of Gutzwiller wave functions in finite dimensions. For this TDGA method, we derive the time-dependent Lagrangian for general single-band Hubbard models.

  2. Compact wave function for bond dissociation and Van der Waals interactions: A natural amplitude assessment

    CERN Document Server

    Giesbertz, K J H

    2014-01-01

    Electron correlations in molecules can be divided in short range dynamical correlations, long range Van der Waals type interactions and near degeneracy static correlations. In this work we analyze how these three types of correlations can be incorporated in a simple wave function of restricted functional form consisting of an orbital product multiplied by a single correlation function $f(r_{12})$ depending on the interelectronic distance $r_{12}$. Since the three types of correlations mentioned lead to different signatures in terms of the natural orbital (NO) amplitudes in two-electron systems we make an analysis of the wave function in terms of the NO amplitudes for a model system of a diatomic molecule. In our numerical implementation we fully optimize the orbitals and the correlation function on a spatial grid without restrictions on their functional form. For the model system we can prove that none of the amplitudes vanishes and moreover that it displays a distinct sign pattern and a series of avoided cro...

  3. The local projection in the density functional theory plus U approach: A critical assessment

    Science.gov (United States)

    Wang, Yue-Chao; Chen, Ze-Hua; Jiang, Hong

    2016-04-01

    Density-functional theory plus the Hubbard U correction (DFT + U) method is widely used in first-principles studies of strongly correlated systems, as it can give qualitatively (and sometimes, semi-quantitatively) correct description of energetic and structural properties of many strongly correlated systems with similar computational cost as local density approximation or generalized gradient approximation. On the other hand, the DFT + U approach is limited both theoretically and practically in several important aspects. In particular, the results of DFT + U often depend on the choice of local orbitals (the local projection) defining the subspace in which the Hubbard U correction is applied. In this work we have systematically investigated the issue of the local projection by considering typical transition metal oxides, β-MnO2 and MnO, and comparing the results obtained from different implementations of DFT + U. We found that the choice of the local projection has significant effects on the DFT + U results, which are more significant for systems with stronger covalent bonding (e.g., MnO2) than those with more ionic bonding (e.g., MnO). These findings can help to clarify some confusion arising from the practical use of DFT + U and may also provide insights for the development of new first-principles approaches beyond DFT + U.

  4. Copper-Catalyzed Redox-Triggered Remote C-H Functionalization: Highly Selective Formation of C-CF3 and C-O Bonds

    Institute of Scientific and Technical Information of China (English)

    Taotao Li; Peng Yu; Jin-Shun Lin; Yonggang Zhi; Xin-Yuan Liu

    2016-01-01

    A Cu-catalyzed remote sp3 C-H/unactivated alkenes functionalization reaction for the concomitant construction ofC-CF3 and C-O bonds was described.An 1,5-H radical transfer involving an sp3 C-H bond adjacent to a nitrogen atom and an α-CF3-alkyl radical intermediate derived from unactivated alkenes was observed and demonstrated to proceed via the radical process.

  5. Application of Functional-notional Approach in Institutional Settings

    OpenAIRE

    大山, 中勝; オオヤマ, ナカカツ; Ohyama, Nakakatsu

    1999-01-01

    This paper presents the analysis of five major language functions. This analysis is based on the frequency of particular English usage and the actual usage of the language. This process allows the researcher to collect the quantitative and qualitative data in institutional settings. According to the data, he applies a functional-notional approach to meet the English needs of Chiba University administrative employees. He can then suggest the improvement of language programs for specific workpl...

  6. DIRECT APPROACH FOR SOLITON PERTURBATIONS BASED ON THE GREEN'S FUNCTION

    Institute of Scientific and Technical Information of China (English)

    PAN LIU-XIAN; YAN JIA-REN; ZHOU GUANG-HUI

    2001-01-01

    A direct approach has been developed for soliton perturbations based on the Green's function. We first linearized the soliton equation, and then derived the Green's function corresponding to approximation equations of different orders. Finally, we obtained the effects of perturbation on a soliton, namely both the slow time dependence of the soliton parameters and the corrections up to the second-order approximation. The higher-order effects can also be obtained in the same way.

  7. An Architectural Approach for Decoding and Distributing Functions in FPUs in a Functional Processor System

    CERN Document Server

    Nair, T R Gopalakrishnan; Krutthika, H K

    2010-01-01

    The main goal of this research is to develop the concepts of a revolutionary processor system called Functional Processor System. The fairly novel work carried out in this proposal concentrates on decoding of function pipelines and distributing it in FPUs as a part of scheduling approach. As the functional programs are super-level programs that entails requirements only at functional level, decoding of functions and distribution of functions in the heterogeneous functional processor units are a challenge. We explored the possibilities of segregation of the functions from the application program and distributing the functions on the relevant FPUs by using address mapping techniques. Here we pursue the perception of feeding the functions into the processor farm rather than the processor fetching the instructions or functions and executing it. This work is carried out at theoretical levels and it requires a long way to go in the realization of this work in hardware perhaps with a large industrial team with a pra...

  8. Generating function approach to reliability analysis of structural systems

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The generating function approach is an important tool for performance assessment in multi-state systems. Aiming at strength reliability analysis of structural systems, generating function approach is introduced and developed. Static reliability models of statically determinate, indeterminate systems and fatigue reliability models are built by constructing special generating functions, which are used to describe probability distributions of strength (resistance), stress (load) and fatigue life, by defining composite operators of generating functions and performance structure functions thereof. When composition operators are executed, computational costs can be reduced by a big margin by means of collecting like terms. The results of theoretical analysis and numerical simulation show that the generating function approach can be widely used for probability modeling of large complex systems with hierarchical structures due to the unified form, compact expression, computer program realizability and high universality. Because the new method considers twin loads giving rise to component failure dependency, it can provide a theoretical reference and act as a powerful tool for static, dynamic reliability analysis in civil engineering structures and mechanical equipment systems with multi-mode damage coupling.

  9. Metal-Ligand Bonds of Second- and Third-Row d-Block Metals Characterized by Density Functional Theory

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta

    2009-01-01

    metal-ligand bond lengths, and bond enthalpies for many as yet uncharacterized diatomics, of interest to researchers in the field of second- and third-row d-block chemistry. We stress that the success of TPSSh cannot be naively extrapolated to other special situations such as, e.g., metal-metal bonds...

  10. Oxy-functionalization of nucleophilic rhenium(I) metal carbon bonds catalyzed by selenium(IV)

    OpenAIRE

    Tenn, William J., III; Conley, Brian L.; Hovelmann, Claas H.; Ahlquist, Marten; Nielsen, Robert J.; Ess, Daniel H.; Oxgaard, Jonas; Bischof, Steven M.; Goddard, William A.; Periana, Roy A.

    2009-01-01

    We report that SeO_2 catalyzes the facile oxy-functionalization of (CO)_5Re(I)-Me^(δ−) with IO_4− to generate methanol. Mechanistic studies and DFT calculations reveal that catalysis involves methyl group transfer from Re to the electrophilic Se center followed by oxidation and subsequent reductive functionalization of the resulting CH_3Se(VI) species. Furthermore, (CO)_3Re(I)(Bpy)-R (R = ethyl, n-propyl, and aryl) complexes show analogous transfer to SeO_2 to generate the primary alcohols. T...

  11. Conceptual chemistry approach towards the support effect in supported vanadium oxides : Valence bond calculations on the ionicity of vanadium catalysts

    NARCIS (Netherlands)

    Fievez, Tim; De Proft, Frank; Geerlings, Paul; Weckhuysen, Bert M.; Havenith, Remco W. A.

    2011-01-01

    The concept of bond ionicity, obtained via a valence bond analysis, is invoked in the interpretation of the catalytic activity of supported vanadium oxides, in analogy with previous work conducted within the framework of conceptual DFT. For a set of model clusters representing the vanadium oxide sup

  12. Bonding thermoplastic polymers

    Science.gov (United States)

    Wallow, Thomas I.; Hunter, Marion C.; Krafcik, Karen Lee; Morales, Alfredo M.; Simmons, Blake A.; Domeier, Linda A.

    2008-06-24

    We demonstrate a new method for joining patterned thermoplastic parts into layered structures. The method takes advantage of case-II permeant diffusion to generate dimensionally controlled, activated bonding layers at the surfaces being joined. It is capable of producing bonds characterized by cohesive failure while preserving the fidelity of patterned features in the bonding surfaces. This approach is uniquely suited to production of microfluidic multilayer structures, as it allows the bond-forming interface between plastic parts to be precisely manipulated at micrometer length scales. The bond enhancing procedure is easily integrated in standard process flows and requires no specialized equipment.

  13. Reaction Development on π- and σ-Conjugated Bonds and Creation of Innovative Functions.

    Science.gov (United States)

    Takita, Ryo

    2016-01-01

    Monocarba-closo-dodecaborate (1; [closo-CB11H12](-), or C1-carborane anion) is a symmetrical, stable anionic cluster, which possesses low nucleophilicity/basicity and exhibits three-dimensional aromaticity. In contrast to the rich applications of C2-carborane molecules (C2B10H12), the chemistry of the C1-carborane anion as a platform for functional molecules has not been thoroughly studied thus far due to the lack of its efficient functionalization. In particular, no efficient general methods are available for the introduction of aryl and sp(2)/sp-carbon groups at the carbon vertex of the C1-carborane anion. The unique electronic structure and potential applications of the C1-carborane anion prompted us to investigate methods to functionalize it. We developed a general, efficient C-C cross-coupling reaction of 1 under palladium catalysis which yields a variety of 1-C-functionalized C1-carborane derivatives. The use of copper(I) or lithium species as a transmetalating partner facilitated the cross-coupling process of the sterically hindered C1-carborane anion. The potential application of 1-C-arylated C1-carborane anion derivatives thus obtained were explored, some of which showed potential as pharmacophores and ionic liquid crystal behavior. Furthermore, conjugation between σ- and π-aromatic moieties in 1-C-arylated monocarba-closo-dodecaborate anion derivatives was identified by means of kinetic experimental studies combined with theoretical calculations. PMID:27252066

  14. The Specific Role of Childhood Abuse, Parental Bonding, and Family Functioning in Female Adolescents With Borderline Personality Disorder.

    Science.gov (United States)

    Infurna, Maria Rita; Brunner, Romuald; Holz, Birger; Parzer, Peter; Giannone, Francesca; Reichl, Corinna; Fischer, Gloria; Resch, Franz; Kaess, Michael

    2016-04-01

    This study examined a broad variety of adverse childhood experiences in a consecutive sample of female adolescent inpatients with borderline personality disorder (BPD; n = 44) compared with a clinical control (CC; n = 47) group with mixed psychiatric diagnoses. BPD was diagnosed using a structured clinical interview; different dimensions of childhood adversity were assessed using the Childhood Experiences of Care and Abuse Questionnaire, the Parental Bonding Instrument, and the Family Assessment Device. A history of childhood adversity was significantly more common in patients with BPD than in the CC group. Using a multivariate model, sexual abuse (OR = 13.8), general family functioning (OR = 8.9), and low maternal care (OR = 7.6) were specific and independent predictors of adolescent BPD. The results increase our knowledge of the specific role of different dimensions of childhood adversity in adolescent BPD. They have important implications for prevention and early intervention as they highlight the need for specific strategies for involving the family. PMID:25905734

  15. A hybrid-exchange density functional study of the bonding and electronic structure in bulk CuFeS2

    Science.gov (United States)

    Martínez-Casado, Ruth; Chen, Vincent H.-Y.; Mallia, Giuseppe; Harrison, Nicholas M.

    2016-05-01

    The geometric, electronic, and magnetic properties of bulk chalcopyrite CuFeS2 have been investigated using hybrid-exchange density functional theory calculations. The results are compared with available theoretical and experimental data. The theoretical description of the bonding and electronic structure in CuFeS2 is analyzed in detail and compared to those computed for chalcocite (CuS2) and greigite (Fe3S4). In particular, the behavior of the 3d electrons of Fe3+ is discussed in terms of the Hubbard-Anderson model in the strongly correlated regime and found to be similarly described in both materials by an on-site Coulomb repulsion (U) of ˜8.9 eV and a transfer integral (t) of ˜0.3 eV.

  16. A Comprehensive Approach for Pectin Chemical and Functional Characterization

    DEFF Research Database (Denmark)

    de Sousa, António Felipe Gomes Teixeira

    In this work, a comprehensive approach for the chemical and functional analysis of pectin was used in order to relate the different extraction conditions used to the polymer structure and the final functional (mainly gelling) properties. A wide range of methods were utilized including chemical...... and chromatographic characterization methods (HPAEC and HPSEC), rheological measurements of elasticity, and biological epitopes detection using carbohydrate microarrays. The end product of this study is expected to contribute to the knowledge of pectin polymeric conformation and structure-function properties as well...

  17. Questionnaire of Executive Function for Dancers: An Ecological Approach

    Science.gov (United States)

    Wong, Alina; Rodriguez, Mabel; Quevedo, Liliana; de Cossio, Lourdes Fernandez; Borges, Ariel; Reyes, Alicia; Corral, Roberto; Blanco, Florentino; Alvarez, Miguel

    2012-01-01

    There is a current debate about the ecological validity of executive function (EF) tests. Consistent with the verisimilitude approach, this research proposes the Ballet Executive Scale (BES), a self-rating questionnaire that assimilates idiosyncratic executive behaviors of classical dance community. The BES was administrated to 149 adolescents,…

  18. From Equation to Inequality Using a Function-Based Approach

    Science.gov (United States)

    Verikios, Petros; Farmaki, Vassiliki

    2010-01-01

    This article presents features of a qualitative research study concerning the teaching and learning of school algebra using a function-based approach in a grade 8 class, of 23 students, in 26 lessons, in a state school of Athens, in the school year 2003-2004. In this article, we are interested in the inequality concept and our aim is to…

  19. Efficient wave-function matching approach for quantum transport calculations

    DEFF Research Database (Denmark)

    Sørensen, Hans Henrik Brandenborg; Hansen, Per Christian; Petersen, Dan Erik;

    2009-01-01

    the propagating and evanescent bulk modes of the left and right electrodes in order to obtain the correct coupling between device and electrode regions. In this paper we will describe a modified WFM approach that allows for the exclusion of the vast majority of the evanescent modes in all parts of the calculation......The wave-function matching (WFM) technique has recently been developed for the calculation of electronic transport in quantum two-probe systems. In terms of efficiency it is comparable to the widely used Green's function approach. The WFM formalism presented so far requires the evaluation of all....... This approach makes it feasible to apply iterative techniques to efficiently determine the few required bulk modes, which allows for a significant reduction of the computational expense of the WFM method. We illustrate the efficiency of the method on a carbon nanotube field-effect-transistor device displaying...

  20. Approaches for functional analysis of flagellar proteins in African trypanosomes.

    Science.gov (United States)

    Oberholzer, Michael; Lopez, Miguel A; Ralston, Katherine S; Hill, Kent L

    2009-01-01

    The eukaryotic flagellum is a highly conserved organelle serving motility, sensory, and transport functions. Although genetic, genomic, and proteomic studies have led to the identification of hundreds of flagellar and putative flagellar proteins, precisely how these proteins function individually and collectively to drive flagellum motility and other functions remains to be determined. In this chapter we provide an overview of tools and approaches available for studying flagellum protein function in the protozoan parasite Trypanosoma brucei. We begin by outlining techniques for in vitro cultivation of both T. brucei life cycle stages, as well as transfection protocols for the delivery of DNA constructs. We then describe specific assays used to assess flagellum function including flagellum preparation and quantitative motility assays. We conclude the chapter with a description of molecular genetic approaches for manipulating gene function. In summary, the availability of potent molecular tools, as well as the health and economic relevance of T. brucei as a pathogen, combine to make the parasite an attractive and integral experimental system for the functional analysis of flagellar proteins. PMID:20409810

  1. Functional systemic approach to the resuscitation and intensive care

    Directory of Open Access Journals (Sweden)

    Sadchikov D.V.

    2014-09-01

    Full Text Available Functional systemic approach to the resuscitation and intensive care may be considered as a direct correlation between analysis and synthesis, induction and deduction, and, in general, between the formal and dialectical categories. The realization of this system should be started with the interaction and formation of the final beneficial result. Therefore the experience assessment on the basis of functional systematic approach will enable us to formulate more precisely the subject and methods of resuscitation from the philosophical point of view taking into consideration the interaction of the human life integrity with death phenomenon as fixed in ontogenesis and will allow to methodically justify the distinguishing of functional systems and standard processes both in sanogenesis and thanatogenesis.

  2. Emerging approaches to probing ion channel structure and function

    Institute of Scientific and Technical Information of China (English)

    Wei-Guang Li; Tian-Le Xu

    2012-01-01

    Ion channels,as membrane proteins,are the sensors of the cell.They act as the first line of communication with the world beyond the plasma membrane and transduce changes in the external and internal environments into unique electrical signals to shape the responses of excitable cells.Because of their importance in cellular communication,ion channels have been intensively studied at the structural and functional levels.Here,we summarize the diverse approaches,including molecular and cellular,chemical,optical,biophysical,and computational,used to probe the structural and functional rearrangements that occur during channel activation (or sensitization),inactivation (or desensitization),and various forms of modulation.The emerging insights into the structure and function of ion channels by multidisciplinary approaches allow the development of new pharmacotherapies as well as new tools useful in controlling cellular activity.

  3. Form factor approach to dynamical correlation functions in critical models

    CERN Document Server

    Kitanine, N; Maillet, J M; Slavnov, N A; Terras, V

    2012-01-01

    We develop a form factor approach to the study of dynamical correlation functions of quantum integrable models in the critical regime. As an example, we consider the quantum non-linear Schr\\"odinger model. We derive long-distance/long-time asymptotic behavior of various two-point functions of this model. We also compute edge exponents and amplitudes characterizing the power-law behavior of dynamical response functions on the particle/hole excitation thresholds. These last results confirm predictions based on the non-linear Luttinger liquid method. Our results rely on a first principles derivation, based on the microscopic analysis of the model, without invoking, at any stage, some correspondence with a continuous field theory. Furthermore, our approach only makes use of certain general properties of the model, so that it should be applicable, with possibly minor modifications, to a wide class of (not necessarily integrable) gapless one dimensional Hamiltonians.

  4. Statistical approach of functional profiling for a microbial community.

    Directory of Open Access Journals (Sweden)

    Lingling An

    Full Text Available Metagenomics is a relatively new but fast growing field within environmental biology and medical sciences. It enables researchers to understand the diversity of microbes, their functions, cooperation, and evolution in a particular ecosystem. Traditional methods in genomics and microbiology are not efficient in capturing the structure of the microbial community in an environment. Nowadays, high-throughput next-generation sequencing technologies are powerfully driving the metagenomic studies. However, there is an urgent need to develop efficient statistical methods and computational algorithms to rapidly analyze the massive metagenomic short sequencing data and to accurately detect the features/functions present in the microbial community. Although several issues about functions of metagenomes at pathways or subsystems level have been investigated, there is a lack of studies focusing on functional analysis at a low level of a hierarchical functional tree, such as SEED subsystem tree.A two-step statistical procedure (metaFunction is proposed to detect all possible functional roles at the low level from a metagenomic sample/community. In the first step a statistical mixture model is proposed at the base of gene codons to estimate the abundances for the candidate functional roles, with sequencing error being considered. As a gene could be involved in multiple biological processes the functional assignment is therefore adjusted by utilizing an error distribution in the second step. The performance of the proposed procedure is evaluated through comprehensive simulation studies. Compared with other existing methods in metagenomic functional analysis the new approach is more accurate in assigning reads to functional roles, and therefore at more general levels. The method is also employed to analyze two real data sets.metaFunction is a powerful tool in accurate profiling functions in a metagenomic sample.

  5. Green's function approach to edge states in transition metal dichalcogenides

    Science.gov (United States)

    Farmanbar, Mojtaba; Amlaki, Taher; Brocks, Geert

    2016-05-01

    The semiconducting two-dimensional transition metal dichalcogenides MX 2 show an abundance of one-dimensional metallic edges and grain boundaries. Standard techniques for calculating edge states typically model nanoribbons, and require the use of supercells. In this paper, we formulate a Green's function technique for calculating edge states of (semi-)infinite two-dimensional systems with a single well-defined edge or grain boundary. We express Green's functions in terms of Bloch matrices, constructed from the solutions of a quadratic eigenvalue equation. The technique can be applied to any localized basis representation of the Hamiltonian. Here, we use it to calculate edge states of MX 2 monolayers by means of tight-binding models. Aside from the basic zigzag and armchair edges, we study edges with a more general orientation, structurally modifed edges, and grain boundaries. A simple three-band model captures an important part of the edge electronic structures. An 11-band model comprising all valence orbitals of the M and X atoms is required to obtain all edge states with energies in the MX 2 band gap. Here, states of odd symmetry with respect to a mirror plane through the layer of M atoms have a dangling-bond character, and tend to pin the Fermi level.

  6. Ensemble density functional theory method correctly describes bond dissociation, excited state electron transfer, and double excitations

    Energy Technology Data Exchange (ETDEWEB)

    Filatov, Michael, E-mail: mike.filatov@gmail.com [Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, Texas 75275-0314 (United States); Huix-Rotllant, Miquel; Burghardt, Irene [Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue-Str. 7, D-60438 Frankfurt am Main (Germany)

    2015-05-14

    State-averaged (SA) variants of the spin-restricted ensemble-referenced Kohn-Sham (REKS) method, SA-REKS and state-interaction (SI)-SA-REKS, implement ensemble density functional theory for variationally obtaining excitation energies of molecular systems. In this work, the currently existing version of the SA-REKS method, which included only one excited state into the ensemble averaging, is extended by adding more excited states to the averaged energy functional. A general strategy for extension of the REKS-type methods to larger ensembles of ground and excited states is outlined and implemented in extended versions of the SA-REKS and SI-SA-REKS methods. The newly developed methods are tested in the calculation of several excited states of ground-state multi-reference systems, such as dissociating hydrogen molecule, and excited states of donor–acceptor molecular systems. For hydrogen molecule, the new method correctly reproduces the distance dependence of the lowest excited state energies and describes an avoided crossing between the doubly excited and singly excited states. For bithiophene–perylenediimide stacked complex, the SI-SA-REKS method correctly describes crossing between the locally excited state and the charge transfer excited state and yields vertical excitation energies in good agreement with the ab initio wavefunction methods.

  7. An Evolutionary Computation Approach to Examine Functional Brain Plasticity.

    Science.gov (United States)

    Roy, Arnab; Campbell, Colin; Bernier, Rachel A; Hillary, Frank G

    2016-01-01

    One common research goal in systems neurosciences is to understand how the functional relationship between a pair of regions of interest (ROIs) evolves over time. Examining neural connectivity in this way is well-suited for the study of developmental processes, learning, and even in recovery or treatment designs in response to injury. For most fMRI based studies, the strength of the functional relationship between two ROIs is defined as the correlation between the average signal representing each region. The drawback to this approach is that much information is lost due to averaging heterogeneous voxels, and therefore, the functional relationship between a ROI-pair that evolve at a spatial scale much finer than the ROIs remain undetected. To address this shortcoming, we introduce a novel evolutionary computation (EC) based voxel-level procedure to examine functional plasticity between an investigator defined ROI-pair by simultaneously using subject-specific BOLD-fMRI data collected from two sessions seperated by finite duration of time. This data-driven procedure detects a sub-region composed of spatially connected voxels from each ROI (a so-called sub-regional-pair) such that the pair shows a significant gain/loss of functional relationship strength across the two time points. The procedure is recursive and iteratively finds all statistically significant sub-regional-pairs within the ROIs. Using this approach, we examine functional plasticity between the default mode network (DMN) and the executive control network (ECN) during recovery from traumatic brain injury (TBI); the study includes 14 TBI and 12 healthy control subjects. We demonstrate that the EC based procedure is able to detect functional plasticity where a traditional averaging based approach fails. The subject-specific plasticity estimates obtained using the EC-procedure are highly consistent across multiple runs. Group-level analyses using these plasticity estimates showed an increase in the strength

  8. An evolutionary computation approach to examine functional brain plasticity

    Directory of Open Access Journals (Sweden)

    Arnab eRoy

    2016-04-01

    Full Text Available One common research goal in systems neurosciences is to understand how the functional relationship between a pair of regions of interest (ROIs evolves over time. Examining neural connectivity in this way is well-suited for the study of developmental processes, learning, and even in recovery or treatment designs in response to injury. For most fMRI based studies, the strength of the functional relationship between two ROIs is defined as the correlation between the average signal representing each region. The drawback to this approach is that much information is lost due to averaging heterogeneous voxels, and therefore, the functional relationship between a ROI-pair that evolve at a spatial scale much finer than the ROIs remain undetected. To address this shortcoming, we introduce a novel evolutionary computation (EC based voxel-level procedure to examine functional plasticity between an investigator defined ROI-pair by simultaneously using subject-specific BOLD-fMRI data collected from two sessions seperated by finite duration of time. This data-driven procedure detects a sub-region composed of spatially connected voxels from each ROI (a so-called sub-regional-pair such that the pair shows a significant gain/loss of functional relationship strength across the two time points. The procedure is recursive and iteratively finds all statistically significant sub-regional-pairs within the ROIs. Using this approach, we examine functional plasticity between the default mode network (DMN and the executive control network (ECN during recovery from traumatic brain injury (TBI; the study includes 14 TBI and 12 healthy control subjects. We demonstrate that the EC based procedure is able to detect functional plasticity where a traditional averaging based approach fails. The subject-specific plasticity estimates obtained using the EC-procedure are highly consistent across multiple runs. Group-level analyses using these plasticity estimates showed an increase in

  9. A radial basis function network approach for the computation of inverse continuous time variant functions.

    Science.gov (United States)

    Mayorga, René V; Carrera, Jonathan

    2007-06-01

    This Paper presents an efficient approach for the fast computation of inverse continuous time variant functions with the proper use of Radial Basis Function Networks (RBFNs). The approach is based on implementing RBFNs for computing inverse continuous time variant functions via an overall damped least squares solution that includes a novel null space vector for singularities prevention. The singularities avoidance null space vector is derived from developing a sufficiency condition for singularities prevention that conduces to establish some characterizing matrices and an associated performance index.

  10. Computational approaches for rational design of proteins with novel functionalities

    Directory of Open Access Journals (Sweden)

    Manish Kumar Tiwari

    2012-09-01

    Full Text Available Proteins are the most multifaceted macromolecules in living systems and have various important functions, including structural, catalytic, sensory, and regulatory functions. Rational design of enzymes is a great challenge to our understanding of protein structure and physical chemistry and has numerous potential applications. Protein design algorithms have been applied to design or engineer proteins that fold, fold faster, catalyze, catalyze faster, signal, and adopt preferred conformational states. The field of de novo protein design, although only a few decades old, is beginning to produce exciting results. Developments in this field are already having a significant impact on biotechnology and chemical biology. The application of powerful computational methods for functional protein designing has recently succeeded at engineering target activities. Here, we review recently reported de novo functional proteins that were developed using various protein design approaches, including rational design, computational optimization, and selection from combinatorial libraries, highlighting recent advances and successes.

  11. Computational approaches for rational design of proteins with novel functionalities.

    Science.gov (United States)

    Tiwari, Manish Kumar; Singh, Ranjitha; Singh, Raushan Kumar; Kim, In-Won; Lee, Jung-Kul

    2012-01-01

    Proteins are the most multifaceted macromolecules in living systems and have various important functions, including structural, catalytic, sensory, and regulatory functions. Rational design of enzymes is a great challenge to our understanding of protein structure and physical chemistry and has numerous potential applications. Protein design algorithms have been applied to design or engineer proteins that fold, fold faster, catalyze, catalyze faster, signal, and adopt preferred conformational states. The field of de novo protein design, although only a few decades old, is beginning to produce exciting results. Developments in this field are already having a significant impact on biotechnology and chemical biology. The application of powerful computational methods for functional protein designing has recently succeeded at engineering target activities. Here, we review recently reported de novo functional proteins that were developed using various protein design approaches, including rational design, computational optimization, and selection from combinatorial libraries, highlighting recent advances and successes.

  12. A new approach to the gluon structure function

    International Nuclear Information System (INIS)

    We calculate the gluon structure function of a color dipole in a new approach evaluating the matrix element of gluon field operators separated along a direction close to the light cone. As vacuum state in the pure glue sector, we use a variational ground state of the near-light-cone Hamiltonian. With a mean momentum fraction of the gluons fixed to the ''experimental value'' in a proton, the resulting gluon structure function for a dipole state with four links is rather close to the NLO MRST 2002 and the CTEQAB-0 parameterizations at Q2=1.5 GeV2.

  13. Linear optical properties and their bond length dependence of yttrium bromide from ab initio and density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Alipour, Mojtaba, E-mail: malipour@shirazu.ac.ir [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Mohajeri, Afshan, E-mail: amohajeri@shirazu.ac.ir [Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

    2011-08-25

    Graphical abstract: The electronic properties such as the static dipole polarizability, anisotropy of the polarizability, and dipole moment of yttrium bromide, YBr (X{sup 1}{Sigma}) have been theoretically studied. Highlights: {yields} Conventional ab initio and density functional theory methods were employed to study linear optical properties of YBr molecule. {yields} Properties derivatives and their level of theory dependence were studied. {yields} Electron correlation effects and rovibrational corrections have also been discussed. - Abstract: We have employed conventional ab initio and density functional theory methods to study the electronic properties such as the mean static dipole polarizability, {alpha}-bar, anisotropy of the polarizability, {Delta}{alpha}, and dipole moment, {mu}, of yttrium bromide. The bond length dependence of properties is determined at different levels of theory and appropriate expansions around experimental internuclear distance have been presented. Moreover, the first and second geometrical derivatives for each property are quantified and their level of theory dependence has been analyzed. To study the effect of molecular rotation and vibration on the electronic properties, the rovibrational corrections have also been carried out. It is found that these corrections are less pronounced for considered properties of YBr. In all calculations, the electron correlation effects have been considered and discussed. The obtained results show that the electron correlation is more significant in the calculation of the mean and the anisotropy of dipole polarizability.

  14. Unified approach to partition functions of RNA secondary structures.

    Science.gov (United States)

    Bundschuh, Ralf

    2014-11-01

    RNA secondary structure formation is a field of considerable biological interest as well as a model system for understanding generic properties of heteropolymer folding. This system is particularly attractive because the partition function and thus all thermodynamic properties of RNA secondary structure ensembles can be calculated numerically in polynomial time for arbitrary sequences and homopolymer models admit analytical solutions. Such solutions for many different aspects of the combinatorics of RNA secondary structure formation share the property that the final solution depends on differences of statistical weights rather than on the weights alone. Here, we present a unified approach to a large class of problems in the field of RNA secondary structure formation. We prove a generic theorem for the calculation of RNA folding partition functions. Then, we show that this approach can be applied to the study of the molten-native transition, denaturation of RNA molecules, as well as to studies of the glass phase of random RNA sequences.

  15. New approach to equipment quality evaluation method with distinct functions

    Directory of Open Access Journals (Sweden)

    Milisavljević Vladimir M.

    2016-01-01

    Full Text Available The paper presents new approach for improving method for quality evaluation and selection of equipment (devices and machinery by applying distinct functions. Quality evaluation and selection of devices and machinery is a multi-criteria problem which involves the consideration of numerous parameters of various origins. Original selection method with distinct functions is based on technical parameters with arbitrary evaluation of each parameter importance (weighting. Improvement of this method, presented in this paper, addresses the issue of weighting of parameters by using Delphi Method. Finally, two case studies are provided, which included quality evaluation of standard boilers for heating and evaluation of load-haul-dump (LHD machines, to demonstrate applicability of this approach. Analytical Hierarchical Process (AHP is used as a control method.

  16. Mechanistic approaches to the study of evolution: the functional synthesis

    OpenAIRE

    Dean, Antony M; Joseph W Thornton

    2007-01-01

    An emerging synthesis of evolutionary biology and experimental molecular biology is providing much stronger and deeper inferences about the dynamics and mechanisms of evolution than were possible in the past. The new approach combines statistical analyses of gene sequences with manipulative molecular experiments to reveal how ancient mutations altered biochemical processes and produced novel phenotypes. This functional synthesis has set the stage for major advances in our understanding of fun...

  17. Language: A Typological, Functional, Cognitive, Biological and Evolutionary Approach.

    OpenAIRE

    Kirtchuk, Pablo

    2009-01-01

    The paper shows the inadequacy of the structuralist method with its climax in generative grammar method when applied to our understanding of langauge. It shows the adequation of the cognitive, typological and functional approach. based on croslinguistically empirical data, i show the intrinsically human nature of language, which distinguishes it from other communication sysrtemss, viz. animal, computer and artificial ones,. Points treated in some detail are : Iconicity, Deixis, Multiple encod...

  18. Fuzzy set approach to quality function deployment: An investigation

    Science.gov (United States)

    Masud, Abu S. M.

    1992-01-01

    The final report of the 1992 NASA/ASEE Summer Faculty Fellowship at the Space Exploration Initiative Office (SEIO) in Langley Research Center is presented. Quality Function Deployment (QFD) is a process, focused on facilitating the integration of the customer's voice in the design and development of a product or service. Various input, in the form of judgements and evaluations, are required during the QFD analyses. All the input variables in these analyses are treated as numeric variables. The purpose of the research was to investigate how QFD analyses can be performed when some or all of the input variables are treated as linguistic variables with values expressed as fuzzy numbers. The reason for this consideration is that human judgement, perception, and cognition are often ambiguous and are better represented as fuzzy numbers. Two approaches for using fuzzy sets in QFD have been proposed. In both cases, all the input variables are considered as linguistic variables with values indicated as linguistic expressions. These expressions are then converted to fuzzy numbers. The difference between the two approaches is due to how the QFD computations are performed with these fuzzy numbers. In Approach 1, the fuzzy numbers are first converted to their equivalent crisp scores and then the QFD computations are performed using these crisp scores. As a result, the output of this approach are crisp numbers, similar to those in traditional QFD. In Approach 2, all the QFD computations are performed with the fuzzy numbers and the output are fuzzy numbers also. Both the approaches have been explained with the help of illustrative examples of QFD application. Approach 2 has also been applied in a QFD application exercise in SEIO, involving a 'mini moon rover' design. The mini moon rover is a proposed tele-operated vehicle that will traverse and perform various tasks, including autonomous operations, on the moon surface. The output of the moon rover application exercise is a

  19. 样条函数在构造债券收益率曲线中的应用%APPLICATION OF SPLINE FUNCTION IN CONSTRUCTING BOND YIELD CURVE

    Institute of Scientific and Technical Information of China (English)

    杨柳

    2016-01-01

    针对债券市场上芜杂的行情数据,提出将DBSCAN聚类算法应用于构造债券收益率曲线样条函数。通过运用DBSCAN算法对用于构造债券收益率曲线的行情数据进行聚类分析,能够有效地剔除市场上的异常交易数据。在聚类分析结果的基础上,再次应用DBSCAN算法于构造债券收益率曲线,根据市场上行情数据的密集区域对样条函数进行分段。此外,针对传统的依赖于经验进行债券收益率曲线样条函数分段点选取的缺点,使用DBSCAN算法可有效地提高债券收益率曲线和行情数据的符合程度。实验结果表明,将DBSCAN算法用于构建债券收益率曲线样条函数,可以提高收益率曲线反映利率期限结构波动及准确性的效果。%In light of the miscellaneous quotation data in bond market,we proposed to apply the DBSCAN algorithm to constructing the spline function of bond yield curve.By employing DBSCAN algorithm to the cluster analysis of the quotation data,which is used to construct bond yield curve,it is able to eliminate effectively the abnormal transaction data on the market.On the basis of cluster analysis results,we used the DBSCAN algorithm once again to construct the bond yield curve,and segmented the spline function into sections according to the dense regions of quotation data on the market.Besides,targeted at the defect of traditional way that it selects the segment points of spline function of bond yield curve depending on experience,the use of DBSCAN algorithm can effectively improve the conformance between the bond yield curve and the bond quotation data.From the experimental results it is illustrated that to apply the DBSCAN algorithm to constructing the spline function of bond yield curve can improve the effects of reflecting the fluctuations of interest term structure by bond yield curve and its accuracy.

  20. Controlled Chemistry Approach to the Oxo-Functionalization of Graphene.

    Science.gov (United States)

    Eigler, Siegfried

    2016-05-17

    Graphene is the best-studied 2D material available. However, its production is still challenging and the quality depends on the preparation procedure. Now, more than a decade after the outstanding experiments conducted on graphene, the most successful wet-chemical approach to graphene and functionalized graphene is based on the oxidation of graphite. Graphene oxide has been known for more than a century; however, the structure bears variable large amounts of lattice defects that render the development of a controlled chemistry impossible. The controlled oxo-functionalization of graphene avoids the formation of defects within the σ-framework of carbon atoms, making the synthesis of specific molecular architectures possible. The scope of this review is to introduce the field of oxo-functionalizing graphene. In particular, the differences between GO and oxo-functionalized graphene are described in detail. Moreover analytical methods that allow determining lattice defects and functional groups are introduced followed by summarizing the current state of controlled oxo-functionalization of graphene. PMID:26990805

  1. Theoretical study on β-aminoacroleine; Density functional theory, atoms in molecules theory and natural bond orbitals studies

    Indian Academy of Sciences (India)

    Heidar Raissi; Mehdi Yoosefian; Effat Moshfeghi; Farzaneh Farzad

    2012-05-01

    The characteristics of the intramolecular hydrogen bonding for a series of 19 different derivatives of -aminoacroleine have been systematically analysed at the B3LYP/6-31G∗∗ level of theory. The topological properties of the electron density distributions for N-H$\\cdots$O intramolecular bridges have been analysed by the Bader theory of atoms in molecules. The electron density () and Laplacian (∇2 ρ) properties at critical points of the relevant bonds, estimated by AIM calculations, showed that N-H$\\cdots$O have low and positive character (∇2 ρ > 0), consistent with electrostatic character of the hydrogen bond. The vibrational study of the hydrogen bonded systems showed negative (red) shifts for the (N−H) stretching mode. The -electron delocalization parameter () as a geometrical indicator of a local aromaticity and the geometry-based HOMA have also been calculated. Furthermore, the analysis of hydrogen bond in this molecule and its derivatives by natural bond orbital (NBO) methods support the DFT results. The results of AIM and NBO analysis as well as (N−H) were further used for estimation of the hydrogen bonding interactions and the forces driving their formation. The various correlations were found between geometrical, energetic and topological parameters. The substituent effect was also analysed and it was found that the strongest hydrogen bonds exist for N+(CH3)3 and Cl substituents while the weakest ones for COOCH3.

  2. Properties and structure of the functional composite materials - Nd-Fe-Co-B powder bonded with polymer

    OpenAIRE

    B. Ziębowicz; M. Dziekońska; L.A. Dobrzański

    2011-01-01

    Purpose: This paper presents the material and technological solution which makes it possible obtaining functional composite materials based on the nanocrystalline Nd-Fe-Co-B powder with polymer matrix and shows the possibility of application in different branches of the techniques.Design/methodology/approach: For fabrication of composite materials: Nd-Fe-Co-B powder obtained by rapid quenched technique and for matrix - high density pressureless polyethylene (PEHD) and polyamide (PA12) (2.5 %...

  3. Self-Reported Emotional and Behavioral Problems, Family Functioning and Parental Bonding among Psychiatric Outpatient Adolescent Offspring of Croatian Male Veterans with Partial PTSD

    Science.gov (United States)

    Sarajlic Vukovic, Iris; Boricevic Maršanic, Vlatka; Aukst Margetic, Branka; Paradžik, Ljubica; Vidovic, Domagoj; Buljan Flander, Gordana

    2015-01-01

    Background: Posttraumatic stress disorder (PTSD) in male veterans has been linked with impaired family relationships and psychopathology in their children. Less is known about symptoms in children of veterans with partial PTSD. Objective: To compare mental health problems, family functioning and parent-child bonding among adolescent offspring of…

  4. Rigorous Description Of Design Components Functionality: An Approach Based Contract

    Directory of Open Access Journals (Sweden)

    Abdelhafid Zitouni

    2012-01-01

    Full Text Available Current models for software components have made component-based software engineering practical. However, these models are limited in the sense that their support for the characterization/specification of design components primarily deals with syntactic issues. To avoid mismatch and misuse of components, more comprehensive specification of software components is required, In this paper, we present a contract-based approach to analyze and model the both aspects (functional and non-functional properties of design components and their composition in order to detect and correct composition errors. This approach permits to characterize the structural, interface and behavioural aspects of design component. To enable this we present a pattern contract language that captures the structural and behavioral requirements associated with a range of patterns, as well as the system properties that are guaranteed as a result. In addition, we propose the use of the LOTOS language as an ADL for formalizing these aspects. We illustrate the approach by applying it to a standard design pattern.

  5. Density functional theory study of interaction, bonding and affinity of group IIb transition metal cations with nucleic acid bases

    Science.gov (United States)

    Bagchi, Sabyasachi; Mandal, Debasish; Ghosh, Deepanwita; Das, Abhijit K.

    2012-05-01

    The structure, bonding, and energetics of the complexes obtained from the interaction between the most stable tautomeric forms of free DNA and RNA bases and Zn2+, Cd2+ and Hg2+ cations have been studied using density functional B3LYP method. The 6-311+G (2df, 2p) basis set along with LANL2DZ pseudopotentials for the cations are used in the calculations. The tautomerization paths of the nucleobases are investigated and transition states between the tautomeric forms of the free bases are located. The relative stability of the complexes and the tautomers of the free nucleobases are discussed referring to MIA and relative energy values. For uracil, thymine and adenine, interaction of the metal cations with the most stable tautomers form the least stable molecular complexes. For cytosine and guanine, the stability of the metalated complexes differs significantly. The enthalpy (ΔH), entropy (TΔS) and free energy (ΔG) of the complexes at 298 K have also been calculated.

  6. Density Functional Method Studies of X-H (X=C, N, O, Si, P, S) Bond Dissociation Energies

    Institute of Scientific and Technical Information of China (English)

    FU Yao; DONG Xiao-Yu; WANG Yi-Min; LIU Lei; GUO Qing-Xiang

    2005-01-01

    The performances of the density functional theory (DFT) methods in calculating X-H bond dissociation energies (BDE, X=C, N, O, Si, P, S) were evaluated. It was found that most DFT methods including B3LYP, B3PW91,G96LYP, PBE1PBE and BH&HLYP significantly underestimated the X-H BDE by as much as 13-24 kJ/mol.The underestimation is not due to the use of finite basis set, because the DFT methods still significantly underestimate the X-H BDE with the complete basis set. Therefore, these DFT methods can not be used to calculate the BDE directly. Nevertheless, the B3P86 method shows very small underestimation for the X-H BDE. Further analysis suggests that there be no advantage for using the restricted open-shell DFT methods. The unrestricted DFT methods actually perform slightly better than the restricted open-shell DFT methods in most cases. Finally, it was found that the underestimation by the DFT methods was largely systematic. The use of the calibrated UDFT/6-311+ + G(d, p) method was recommended to calculate the X-H BDE.

  7. Nuclear Functions of Nucleolin through Global Proteomics and Interactomic Approaches.

    Science.gov (United States)

    Salvetti, Anna; Couté, Yohann; Epstein, Alberto; Arata, Loredana; Kraut, Alexandra; Navratil, Vincent; Bouvet, Philippe; Greco, Anna

    2016-05-01

    Nucleolin (NCL) is a major component of the cell nucleolus, which has the ability to rapidly shuttle to several other cells' compartments. NCL plays important roles in a variety of essential functions, among which are ribosome biogenesis, gene expression, and cell growth. However, the precise mechanisms underlying NCL functions are still unclear. Our study aimed to provide new information on NCL functions via the identification of its nuclear interacting partners. Using an interactomics approach, we identified 140 proteins co-purified with NCL, among which 100 of them were specifically found to be associated with NCL after RNase digestion. The functional classification of these proteins confirmed the prominent role of NCL in ribosome biogenesis and additionally revealed the possible involvement of nuclear NCL in several pre-mRNA processing pathways through its interaction with RNA helicases and proteins participating in pre-mRNA splicing, transport, or stability. NCL knockdown experiments revealed that NCL regulates the localization of EXOSC10 and the amount of ZC3HAV1, two components of the RNA exosome, further suggesting its involvement in the control of mRNA stability. Altogether, this study describes the first nuclear interactome of human NCL and provides the basis for further understanding the mechanisms underlying the essential functions of this nucleolar protein. PMID:27049334

  8. Correlation functions of the spin chains. Algebraic Bethe Ansatz approach

    International Nuclear Information System (INIS)

    Spin chains are the basic elements of integrable quantum models. These models have direct applications in condense matter theory, in statistical physics, in quantum optics, in field theory and even in string theory but they are also important because they enable us to solve, in an exact manner, non-perturbative phenomena that otherwise would stay unresolved. The method described in this work is based on the algebraic Bethe Ansatz. It is shown how this method can be used for the computation of null temperature correlation functions of the Heisenberg 1/2 spin chain. The important point of this approach is the solution of the inverse quantum problem given by the XXZ spin chain. This solution as well as a simple formulae for the scalar product of the Bethe states, have enabled us to get the most basic correlation functions under the form of multiple integrals. The formalism of multiple integrals open the way for asymptotic analysis for a few physical quantities like the probability of vacuum formation. It is worth noticing that this formalism can give exact results for two-point functions that are the most important correlation functions for applications. A relationship has been discovered between these multiple integrals and the sum of the form factors. The results have been extended to dynamical correlation functions. (A.C.)

  9. Dual Approach to the Study of Land Market Functioning

    Directory of Open Access Journals (Sweden)

    Liliya Oganesovna Oganesyan

    2015-12-01

    Full Text Available The article reveals the essence, the structural elements and features of the mechanism of functioning of the market of agricultural land. The authors present the supplementing idea on the structural dichotomy of the agricultural land market. In contrast to neoclassical approaches, it is proposed to explore the market based on its structural dichotomy – market property rights and market rights of management. In this context, the mechanism of functioning of agricultural lands market performs the function of a basic element in the system of land relations to ensure market circulation of agricultural land through alienation and assign full or partial rights of land ownership. The use of the institutional approach to the study of market structures justifies the dual nature of the mechanism of functioning of the market of agricultural land due to the fact that on the one hand, the market is slow and limited in the market space of the rare economic good or factor of production, and on the other hand, it is a dynamic institutional and economic system within which the specification of property rights to land is implemented. The structure of the mechanism of functioning and development of agricultural land market is considered as a system of interrelated and interacting elements of state regulation and market self-regulation, based on the principles of coordination and harmonization of personalized economic interests and market law of supply and demand. The combination of elements of market self-regulation and state regulation allows in practice to justify the choice of model combinations of stable and changing elements of the mechanism. This combination complies with the institutional conditions for the functioning of the market of agricultural land considering the dominance of regulated sustainable standards at the market of property rights and in the frames of informal institutions at the market of the management rights. The authors prove the

  10. The Navier-Stokes equations an elementary functional analytic approach

    CERN Document Server

    Sohr, Hermann

    2001-01-01

    The primary objective of this monograph is to develop an elementary and self-contained approach to the mathematical theory of a viscous, incompressible fluid in a domain of the Euclidean space, described by the equations of Navier-Stokes. Moreover, the theory is presented for completely general domains, in particular, for arbitrary unbounded, nonsmooth domains. Therefore, restriction was necessary to space dimensions two and three, which are also the most significant from a physical point of view. For mathematical generality, however, the linearized theory is expounded for general dimensions higher than one. Although the functional analytic approach developed here is, in principle, known to specialists, the present book fills a gap in the literature providing a systematic treatment of a subject that has been documented until now only in fragments. The book is mainly directed to students familiar with basic tools in Hilbert and Banach spaces. However, for the readers’ convenience, some fundamental properties...

  11. Green-function approach to the theory of tunneling ionization

    Science.gov (United States)

    Fabrikant, I. I.; Zhao, L. B.

    2015-05-01

    We solve the problem of tunneling ionization of a multielectron atom in a static electric field by using the Green's function for the Stark-Coulomb problem. This allows us to incorporate the outgoing-wave boundary conditions at infinity. The interaction of the active electron with the atomic residue is described either by a model potential or by the l -dependent pseudopotential which prevents virtual transitions to orbitals occupied by inner electrons. The method works well in the broad range of electric fields including the region above the classical ionization threshold (the barrier-suppression region). Calculations of ionization of Ar demonstrate a noticeable difference between the model potential approach and the pseudopotential approach, but both sets of results agree with experimental data.

  12. Sensorimotor integration for functional recovery and the Bobath approach.

    Science.gov (United States)

    Levin, Mindy F; Panturin, Elia

    2011-04-01

    Bobath therapy is used to treat patients with neurological disorders. Bobath practitioners use hands-on approaches to elicit and reestablish typical movement patterns through therapist-controlled sensorimotor experiences within the context of task accomplishment. One aspect of Bobath practice, the recovery of sensorimotor function, is reviewed within the framework of current motor control theories. We focus on the role of sensory information in movement production, the relationship between posture and movement and concepts related to motor recovery and compensation with respect to this therapeutic approach. We suggest that a major barrier to the evaluation of the therapeutic effectiveness of the Bobath concept is the lack of a unified framework for both experimental identification and treatment of neurological motor deficits. More conclusive analysis of therapeutic effectiveness requires the development of specific outcomes that measure movement quality. PMID:21628730

  13. An ecological approach to language development: an alternative functionalism.

    Science.gov (United States)

    Dent, C H

    1990-11-01

    I argue for a new functionalist approach to language development, an ecological approach. A realist orientation is used that locates the causes of language development neither in the child nor in the language environment but in the functioning of perceptual systems that detect language-world relationships and use them to guide attention and action. The theory requires no concept of innateness, thus avoiding problems inherent in either the innate ideas or the genes-as-causal-programs explanations of the source of structure in language. An ecological explanation of language is discussed in relation to concepts and language, language as representation, problems in early word learning, metaphor, and syntactic development. Finally, problems incurred in using the idea of innateness are summarized: History prior to the chosen beginning point is ignored, data on organism-environment mutuality are not collected, and the explanation claims no effect of learning, which cannot be tested empirically.

  14. A novel Bayesian approach to spectral function reconstruction

    CERN Document Server

    Burnier, Yannis

    2013-01-01

    We present a novel approach to the inference of spectral functions from Euclidean time correlator data that makes close contact with modern Bayesian concepts. Our method differs significantly from the maximum entropy method (MEM). A new set of axioms is postulated for the prior probability, leading to an improved expression, which is devoid of the asymptotically flat directions present in the Shanon-Jaynes entropy. Hyperparameters are integrated out explicitly, liberating us from the Gaussian approximations underlying the evidence approach of the MEM. We present a realistic test of our method in the context of the non-perturbative extraction of the heavy quark potential. Based on hard-thermal-loop correlator mock data, we establish firm requirements in the number of data points and their accuracy for a successful extraction of the potential from lattice QCD. An improved potential estimation from previously investigated quenched lattice QCD correlators is provided.

  15. Investigation of Drag Force on Fibres of Bonded Spherical Elements using a Coupled CFD-DEM Approach

    DEFF Research Database (Denmark)

    Jensen, Anna Lyhne; Sørensen, Henrik; Rosendahl, Lasse Aistrup;

    2016-01-01

    are quantified. The drag coefficient on the resolved cylinder is compared to a CFD-DEM simulation of a flexible fiber made by a chain of bonded spherical discrete elements, using a free steam drag formulation on each particle. Based on the results, a drag force model can distinguish between the outermost...

  16. ONION: Functional Approach for Integration of Lipidomics and Transcriptomics Data.

    Directory of Open Access Journals (Sweden)

    Monika Piwowar

    Full Text Available To date, the massive quantity of data generated by high-throughput techniques has not yet met bioinformatics treatment required to make full use of it. This is partially due to a mismatch in experimental and analytical study design but primarily due to a lack of adequate analytical approaches. When integrating multiple data types e.g. transcriptomics and metabolomics, multidimensional statistical methods are currently the techniques of choice. Typical statistical approaches, such as canonical correlation analysis (CCA, that are applied to find associations between metabolites and genes are failing due to small numbers of observations (e.g. conditions, diet etc. in comparison to data size (number of genes, metabolites. Modifications designed to cope with this issue are not ideal due to the need to add simulated data resulting in a lack of p-value computation or by pruning of variables hence losing potentially valid information. Instead, our approach makes use of verified or putative molecular interactions or functional association to guide analysis. The workflow includes dividing of data sets to reach the expected data structure, statistical analysis within groups and interpretation of results. By applying pathway and network analysis, data obtained by various platforms are grouped with moderate stringency to avoid functional bias. As a consequence CCA and other multivariate models can be applied to calculate robust statistics and provide easy to interpret associations between metabolites and genes to leverage understanding of metabolic response. Effective integration of lipidomics and transcriptomics is demonstrated on publically available murine nutrigenomics data sets. We are able to demonstrate that our approach improves detection of genes related to lipid metabolism, in comparison to applying statistics alone. This is measured by increased percentage of explained variance (95% vs. 75-80% and by identifying new metabolite-gene associations

  17. Matrix converter controlled with the direct transfer function approach

    DEFF Research Database (Denmark)

    Rodriguez, J.; Silva, E.; Blaabjerg, Frede;

    2005-01-01

    Power electronics is an emerging technology. New power circuits are invented and have to be introduced into the power electronics curriculum. One of the interesting new circuits is the matrix converter (MC), and this paper analyses its working principles. A simple model is proposed to represent...... the power circuit, including the input filter. The power semiconductors are modelled as ideal bidirectional switches and the MC is controlled using a direct transfer function approach. The modulation strategy of the converter is explained in a complete and clear form. The commutation problem of two switches...

  18. Optical Approach for the Thermal Partition Function of Photons

    OpenAIRE

    Moretti, Valter; Iellici, Devis

    1996-01-01

    The optical manifold method to compute the one-loop effective action in a static space-time is extended from the massless scalar field to the Maxwell field in any Feynman-like covariant gauge. The method is applied to the case of the Rindler space obtaining the same results as the point-splitting procedure. The result is free from Kabat's surface terms which instead affect the $\\zeta$-function or heat-kernel approaches working directly in the static manifold containing conical singularities. ...

  19. An information theoretic approach to the functional classification of neurons

    CERN Document Server

    Schneidman, E; Berry, M J; Schneidman, Elad; Bialek, William; Berry, Michael J.

    2002-01-01

    A population of neurons typically exhibits a broad diversity of responses to sensory inputs. The intuitive notion of functional classification is that cells can be clustered so that most of the diversity is captured in the identity of the clusters rather than by individuals within clusters. We show how this intuition can be made precise using information theory, without any need to introduce a metric on the space of stimuli or responses. Applied to the retinal ganglion cells of the salamander, this approach recovers classical results, but also provides clear evidence for subclasses beyond those identified previously. Further, we find that each of the ganglion cells is functionally unique, and that even within the same subclass only a few spikes are needed to reliably distinguish between cells.

  20. Current approaches on viral infection: proteomics and functional validations

    Directory of Open Access Journals (Sweden)

    Jie eZheng

    2012-11-01

    Full Text Available Viruses could manipulate cellular machinery to ensure their continuous survival and thus become parasites of living organisms. Delineation of sophisticated host responses upon virus infection is a challenging task. It lies in identifying the repertoire of host factors actively involved in the viral infectious cycle and characterizing host responses qualitatively and quantitatively during viral pathogenesis. Mass spectrometry based proteomics could be used to efficiently study pathogen-host interactions and virus-hijacked cellular signaling pathways. Moreover, direct host and viral responses upon infection could be further investigated by activity based functional validation studies. These approaches involve drug inhibition of secretory pathway, immunofluorescence staining, dominant negative mutation of protein target, real time PCR, small interfering siRNA-mediated knockdown, and molecular cloning studies. In this way, functional validation could gain novel insights into the high-content proteomic dataset in an unbiased and comprehensive way.

  1. A Model-Based Approach to Constructing Music Similarity Functions

    Science.gov (United States)

    West, Kris; Lamere, Paul

    2006-12-01

    Several authors have presented systems that estimate the audio similarity of two pieces of music through the calculation of a distance metric, such as the Euclidean distance, between spectral features calculated from the audio, related to the timbre or pitch of the signal. These features can be augmented with other, temporally or rhythmically based features such as zero-crossing rates, beat histograms, or fluctuation patterns to form a more well-rounded music similarity function. It is our contention that perceptual or cultural labels, such as the genre, style, or emotion of the music, are also very important features in the perception of music. These labels help to define complex regions of similarity within the available feature spaces. We demonstrate a machine-learning-based approach to the construction of a similarity metric, which uses this contextual information to project the calculated features into an intermediate space where a music similarity function that incorporates some of the cultural information may be calculated.

  2. Novel metal resistance genes from microorganisms: a functional metagenomic approach.

    Science.gov (United States)

    González-Pastor, José E; Mirete, Salvador

    2010-01-01

    Most of the known metal resistance mechanisms are based on studies of cultured microorganisms, and the abundant uncultured fraction could be an important source of genes responsible for uncharacterized resistance mechanisms. A functional metagenomic approach was selected to recover metal resistance genes from the rhizosphere microbial community of an acid-mine drainage (AMD)-adapted plant, Erica andevalensis, from Rio Tinto, Spain. A total of 13 nickel resistant clones were isolated and analyzed, encoding hypothetical or conserved hypothetical proteins of uncertain functions, or well-characterized proteins, but not previously reported to be related to nickel resistance. The resistance clones were classified into two groups according to their nickel accumulation properties: those preventing or those favoring metal accumulation. Two clones encoding putative ABC transporter components and a serine O-acetyltransferase were found as representatives of each group, respectively. PMID:20830571

  3. Coupled valence bond theory

    NARCIS (Netherlands)

    Havenith, R.W.A.

    2005-01-01

    In this Letter, the formulation and implementation of a parallel response property code for non-orthogonal, valence bond wave-functions are described. Test calculations on benzene and cyclobutadiene show that the polarisability and magnetisability tensors obtained using valence bond theory are compa

  4. Green's function approach for quantum graphs: An overview

    Science.gov (United States)

    Andrade, Fabiano M.; Schmidt, A. G. M.; Vicentini, E.; Cheng, B. K.; da Luz, M. G. E.

    2016-08-01

    Here we review the many aspects and distinct phenomena associated to quantum dynamics on general graph structures. For so, we discuss such class of systems under the energy domain Green's function (G) framework. This approach is particularly interesting because G can be written as a sum over classical-like paths, where local quantum effects are taken into account through the scattering matrix elements (basically, transmission and reflection amplitudes) defined on each one of the graph vertices. Hence, the exact G has the functional form of a generalized semiclassical formula, which through different calculation techniques (addressed in detail here) always can be cast into a closed analytic expression. It allows to solve exactly arbitrary large (although finite) graphs in a recursive and fast way. Using the Green's function method, we survey many properties of open and closed quantum graphs as scattering solutions for the former and eigenspectrum and eigenstates for the latter, also considering quasi-bound states. Concrete examples, like cube, binary trees and Sierpiński-like topologies are presented. Along the work, possible distinct applications using the Green's function methods for quantum graphs are outlined.

  5. Structural, bonding, and electronic properties of the hexagonal ferroelectric and paraelectric phases of LuMnO{sub 3} compound: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, A. M.; Coutinho, W. S.; Lima, A. F.; Lalic, M. V., E-mail: mlalicbr@gmail.com [Physics Department, Federal University of Sergipe, São Cristóvão 49100-000 (Brazil)

    2015-02-21

    We have investigated the structural, bonding, and electronic properties of both ferroelectric (FE) and paraelectric (PE) phases of the hexagonal LuMnO{sub 3} compound using calculations based on density functional theory. The structural properties have been determined by employing the generalized gradient approximation with Perdew-Burke-Ernzerhof and Wu-Cohen parameterization. The bonding and electronic properties have been treated by recently developed modified Becke-Johnson exchange potential, which succeeded to open a band gap for both PE and FE phases, in agreement with experimental predictions. The Bader’s topological analysis of electronic density showed that the character of the Lu–O axial bonds changes when the crystal exhibits the PE → FE structural transition. This fact is in agreement with experimental findings. The covalent character of the Lu–O bond significantly increases due to orbital hybridization between the Lu 5d{sub z}{sup 2} and O 2p{sub z}-states. This bonding mechanism causes the ferroelectricity in the hexagonal LuMnO{sub 3} compound.

  6. Decomposition Pathways of Glycerol via C–H, O–H, and C–C Bond Scission on Pt(111): A Density Functional Theory Study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials; Greeley, Jeffrey [Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials

    2011-09-01

    Glycerol decomposition on Pt(111) via dehydrogenation or C–C bond scission is examined with periodic density functional theory (DFT) calculations. The thermochemistry of dehydrogenation intermediates is first estimated using an empirical correlation scheme with parameters fit to selected DFT calculations; the resulting estimates for the more stable intermediates are refined with full DFT calculations. Brønsted–Evans–Polanyi (BEP) relationships for dehydrogenation and C–C bond scission reactions are developed and used to estimate the kinetics of elementary dehydrogenation and C–C bond scission steps in the reaction network. The combined thermochemical and kinetic analysis implies that glycerol dehydrogenation products at intermediate levels of dehydrogenation are the most thermochemically stable. Additionally, although C–C bond scission transition state energies are high for glycerol and for intermediates at early stages of dehydrogenation, these energies decrease as the intermediates are successively dehydrogenated, reaching a minimum after the removal of several hydrogen atoms from glycerol. At these levels of dehydrogenation, the C–C scission transition state energies become comparable to those of O–H or C–H scission. These results suggest that C–C bonds are only broken after glycerol has been significantly dehydrogenated and demonstrate that DFT-based analyses, combined with simple correlation schemes, can be effective for elucidating general features of complex biomassic reaction networks.

  7. Decomposition Pathways of Glycerol via C–H, O–H, and C–C Bond Scission on Pt(111): A Density Functional Theory Study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Greeley, Jeffrey P.

    2011-10-13

    Glycerol decomposition on Pt(111) via dehydrogenation or C–C bond scission is examined with periodic density functional theory (DFT) calculations. The thermochemistry of dehydrogenation intermediates is first estimated using an empirical correlation scheme with parameters fit to selected DFT calculations; the resulting estimates for the more stable intermediates are refined with full DFT calculations. Brønsted–Evans–Polanyi (BEP) relationships for dehydrogenation and C–C bond scission reactions are developed and used to estimate the kinetics of elementary dehydrogenation and C–C bond scission steps in the reaction network. The combined thermochemical and kinetic analysis implies that glycerol dehydrogenation products at intermediate levels of dehydrogenation are the most thermochemically stable. Additionally, although C–C bond scission transition state energies are high for glycerol and for intermediates at early stages of dehydrogenation, these energies decrease as the intermediates are successively dehydrogenated, reaching a minimum after the removal of several hydrogen atoms from glycerol. At these levels of dehydrogenation, the C–C scission transition state energies become comparable to those of O–H or C–H scission. These results suggest that C–C bonds are only broken after glycerol has been significantly dehydrogenated and demonstrate that DFT-based analyses, combined with simple correlation schemes, can be effective for elucidating general features of complex biomassic reaction networks.

  8. Bond Issues.

    Science.gov (United States)

    Pollack, Rachel H.

    2000-01-01

    Notes trends toward increased borrowing by colleges and universities and offers guidelines for institutions that are considering issuing bonds to raise money for capital projects. Discussion covers advantages of using bond financing, how use of bonds impacts on traditional fund raising, other cautions and concerns, and some troubling aspects of…

  9. The Navier-Stokes equations an elementary functional analytic approach

    CERN Document Server

    Sohr, Hermann

    2001-01-01

    The primary objective of this monograph is to develop an elementary and self­ contained approach to the mathematical theory of a viscous incompressible fluid in a domain 0 of the Euclidean space ]Rn, described by the equations of Navier­ Stokes. The book is mainly directed to students familiar with basic functional analytic tools in Hilbert and Banach spaces. However, for readers' convenience, in the first two chapters we collect without proof some fundamental properties of Sobolev spaces, distributions, operators, etc. Another important objective is to formulate the theory for a completely general domain O. In particular, the theory applies to arbitrary unbounded, non-smooth domains. For this reason, in the nonlinear case, we have to restrict ourselves to space dimensions n = 2,3 that are also most significant from the physical point of view. For mathematical generality, we will develop the lin­ earized theory for all n 2 2. Although the functional-analytic approach developed here is, in principle, known ...

  10. Bayesian field theoretic reconstruction of bond potential and bond mobility in single molecule force spectroscopy

    CERN Document Server

    Chang, Joshua C; Chou, Tom

    2015-01-01

    Quantifying the forces between and within macromolecules is a necessary first step in understanding the mechanics of molecular structure, protein folding, and enzyme function and performance. In such macromolecular settings, dynamic single-molecule force spectroscopy (DFS) has been used to distort bonds. The resulting responses, in the form of rupture forces, work applied, and trajectories of displacements, have been used to reconstruct bond potentials. Such approaches often rely on simple parameterizations of one-dimensional bond potentials, assumptions on equilibrium starting states, and/or large amounts of trajectory data. Parametric approaches typically fail at inferring complex-shaped bond potentials with multiple minima, while piecewise estimation may not guarantee smooth results with the appropriate behavior at large distances. Existing techniques, particularly those based on work theorems, also do not address spatial variations in the diffusivity that may arise from spatially inhomogeneous coupling to...

  11. Molecular and environmental factors governing non-covalent bonding interactions and conformations of phosphorous functionalized γ-cyclodextrin hydrate systems.

    Science.gov (United States)

    Ivanova, Bojidarka; Spiteller, Michael

    2016-06-01

    Recent strategies in molecular drugs-design shift efforts to nanomedicine. Large supra-molecular inclusion systems are implemented as therapeutics. The sophistication of design is based on major advances of cyclodextrins (CDs) as host molecules. They are friendly towards biological environment. CDs have good (bio)compatibility as well. CDs can form host-guest macromolecular systems incorporating small molecules with suitable shapes due to non-covalent interactions. Innovative strategies yield to polymeric nano-particles; micelles; linear polymers and/or CDs-functionalized dendrimeric nanostructures; nanofibers as well as hydrogels. Attractive are phosphorous containing (bio)matrerials, having high selectivity toward biological active molecules. The non-covalent interactions in aquatic CD-systems contribute to stability of host-guest systems under physiological conditions, determining conformational preferences of host-CD macromolecule and guest small molecular template. In this paper we have reported complementation application of mass spectrometric (MS) and quantum chemical analysis of phosphorous chemically substituted γ-cyclodextrin hydrates γ-CDPO/nH2O (n ∊ [0-14]), studying neutral and polynegatively charged molecules as an effort to describe realistic a representative scale of physiological conditions. The binding affinity and molecular conformations are discussed. The 250 neutral and charged systems (γ-CDPOHm/nH2O, n ∊ [10][0,14], m ∊ [0,15], γ-CDPOH-8/nH2O.8Na(+), and γ-CDPOH-16/nH2O.16Na(+)) in four main domains of non-covalent hydrogen bonding interactions are studied. PMID:26944657

  12. A computational approach to the functional screening of genomes.

    Directory of Open Access Journals (Sweden)

    Davide Chiarugi

    2007-09-01

    Full Text Available Comparative genomics usually involves managing the functional aspects of genomes, by simply comparing gene-by-gene functions. Following this approach, Mushegian and Koonin proposed a hypothetical minimal genome, Minimal Gene Set (MGS, aiming for a possible oldest ancestor genome. They obtained MGS by comparing the genomes of two simple bacteria and eliminating duplicated or functionally identical genes. The authors raised the fundamental question of whether a hypothetical organism possessing MGS is able to live or not. We attacked this viability problem specifying in silico the metabolic pathways of the MGS-based prokaryote. We then performed a dynamic simulation of cellular metabolic activities in order to check whether the MGS-prokaryote reaches some equilibrium state and produces the necessary biomass. We assumed these two conditions to be necessary for a living organism. Our simulations clearly show that the MGS does not express an organism that is able to live. We then iteratively proceeded with functional replacements in order to obtain a genome composition that gives rise to equilibrium. We ruled out 76 of the original 254 genes in the MGS, because they resulted in duplication from a functional point of view. We also added seven genes not present in the MGS. These genes encode for enzymes involved in critical nodes of the metabolic network. These modifications led to a genome composed of 187 elements expressing a virtually living organism, Virtual Cell (ViCe, that exhibits homeostatic capabilities and produces biomass. Moreover, the steady-state distribution of the concentrations of virtual metabolites that resulted was similar to that experimentally measured in bacteria. We conclude then that ViCe is able to "live in silico."

  13. Simulation of cement-improved clay structures with a bonded elasto-plastic model: A practical approach

    OpenAIRE

    Arroyo Alvarez de Toledo, Marcos; Ciantia, M.; Castellanza, Riccardo; Gens Solé, Antonio; NOVA, ROBERTO

    2012-01-01

    Engineering practice has usually dealt with the treated soil bodies using simplistic constitutive models (e.g. elastic perfectly-plastic Mohr–Coulomb). In this paper, a more refined bonded elasto-plastic model is here applied, with emphasis on the ease of calibration. Empirical studies have identified the ratio of cement content to the cured mixture void ratio as a controlling variable for mechanical response. This observation is elaborated upon to show that measuring porosity and unconfined ...

  14. Theoretical analysis of the geometrical isotope effect on the hydrogen bonds in photoactive yellow protein with multi-component density functional theory

    International Nuclear Information System (INIS)

    Highlights: • We analyze nuclear quantum effects on hydrogen bonds around the chromophore in the photoactive yellow protein. • Multi-component density functional theory is used to analyze the H/D isotope effect on hydrogen bond distances. • The donor–acceptor distance in the hydrogen bonds are elongated by the deuterium substitution. - Abstract: To theoretically analyze the nuclear quantum effects of protons on two hydrogen bonds around the chromophore (CRO) in the photoactive yellow protein (PYP), we have calculated simple cluster model consisting of CRO, Glu46, and Tyr42 residues in PYP with the multi-component molecular orbital method and multi-component density functional theory, which can take account of quantum fluctuations of light mass particles. The average OO distances between CRO and Glu46 and between CRO and Tyr42 with our methods are shorter than the corresponding equilibrium ones, while the OH distances become longer due to the anharmonicity of the potential. The H/D geometrical isotope effect is also found, that is, the distances between oxygen atoms are elongated by the deuterium substitution, known as Ubbelohde effect

  15. Functional Analysis of Jasmonates in Rice through Mutant Approaches

    Directory of Open Access Journals (Sweden)

    Rohit Dhakarey

    2016-03-01

    Full Text Available Jasmonic acid, one of the major plant hormones, is, unlike other hormones, a lipid-derived compound that is synthesized from the fatty acid linolenic acid. It has been studied intensively in many plant species including Arabidopsis thaliana, in which most of the enzymes participating in its biosynthesis were characterized. In the past 15 years, mutants and transgenic plants affected in the jasmonate pathway became available in rice and facilitate studies on the functions of this hormone in an important crop. Those functions are partially conserved compared to other plant species, and include roles in fertility, response to mechanical wounding and defense against herbivores. However, new and surprising functions have also been uncovered by mutant approaches, such as a close link between light perception and the jasmonate pathway. This was not only useful to show a phenomenon that is unique to rice but also helped to establish this role in plant species where such links are less obvious. This review aims to provide an overview of currently available rice mutants and transgenic plants in the jasmonate pathway and highlights some selected roles of jasmonate in this species, such as photomorphogenesis, and abiotic and biotic stress.

  16. NON FUNCTIONAL REQUIREMENT TRACEABILITY AUTOMATION-AN MOBILE MULTIMEDIA APPROACH

    Directory of Open Access Journals (Sweden)

    J. Selvakumar

    2012-01-01

    Full Text Available Requirements Engineering (RE is the area of software engineering that deals with the discovery and specification of the objectives for the system under development and the environment in which it is used including the human activities it supports. Requirement Elicitation is process of gathering requirements from stakeholders. Incorporating RE to identify non Functional Requirements (NFR in early stages of design and implementation avoids ambiguities, conflicting requirement and other defects. The efficacy of the requirement engineering methodology is its ability to capture NFR in an efficient manner. In this study, we propose a novel method of elicitation using mobile multimedia and to automatically trace the NFR. The requirements description is captured in video using smart phones. Requirement document are prepared using voice to text converter. NFR is detected automatically from the requirement document and hand gestures emphasise the importance of the requirement. It is observed that the precision and recall of the classifiers is better using multimedia data. Features were extracted from video frame and audio using image processing technique and speech processing. We investigated data mining approach to identify Non Functional Requirements (NFR from Functional Requirement (FR Documents. Results obtained were satisfactory.

  17. Convertible bond valuation focusing on Chinese convertible bond market

    OpenAIRE

    Yang, Ke

    2010-01-01

    This paper mainly discusses the methods of valuation of convertible bonds in Chinese market. Different from common convertible bonds in European market, considering the complicate features of Chinese convertible bond, this paper represents specific pricing approaches for pricing convertible bonds with different provisions along with the increment of complexity of these provisions. More specifically, this paper represents the decomposing method and binomial tree method for pricing both of Non-...

  18. Promoting return of function in multiple sclerosis: An integrated approach.

    Science.gov (United States)

    Gacias, Mar; Casaccia, Patrizia

    2013-10-01

    Multiple sclerosis is a disease characterized by inflammatory demyelination, axonal degeneration and progressive brain atrophy. Most of the currently available disease modifying agents proved to be very effective in managing the relapse rate, however progressive neuronal damage continues to occur and leads to progressive accumulation of irreversible disability. For this reason, any therapeutic strategy aimed at restoration of function must take into account not only immunomodulation, but also axonal protection and new myelin formation. We further highlight the importance of an holistic approach, which considers the variability of therapeutic responsiveness as the result of the interplay between genetic differences and the epigenome, which is in turn affected by gender, age and differences in life style including diet, exercise, smoking and social interaction. PMID:24363985

  19. CLARM: An integrative approach for functional modules discovery

    KAUST Repository

    Salem, Saeed M.

    2011-01-01

    Functional module discovery aims to find well-connected subnetworks which can serve as candidate protein complexes. Advances in High-throughput proteomic technologies have enabled the collection of large amount of interaction data as well as gene expression data. We propose, CLARM, a clustering algorithm that integrates gene expression profiles and protein protein interaction network for biological modules discovery. The main premise is that by enriching the interaction network by adding interactions between genes which are highly co-expressed over a wide range of biological and environmental conditions, we can improve the quality of the discovered modules. Protein protein interactions, known protein complexes, and gene expression profiles for diverse environmental conditions from the yeast Saccharomyces cerevisiae were used for evaluate the biological significance of the reported modules. Our experiments show that the CLARM approach is competitive to wellestablished module discovery methods. Copyright © 2011 ACM.

  20. Optical Approach for the Thermal Partition Function of Photons

    CERN Document Server

    Moretti, V; Moretti, Valter; Iellici, Devis

    1997-01-01

    The optical manifold method to compute the one-loop effective action in a static space-time is extended from the massless scalar field to the Maxwell field in any Feynman-like covariant gauge. The method applied in the case of the Rindler space obtaining the same results as the point-splitting procedure. The result is free from Kabat's surface terms which instead affect the manifold containing conical singularities. The relation between the optical method and the direct $\\zeta$-function approach on the Euclidean Rindler manifold is discussed both in the scalar and the photon case. Problems with the thermodynamic consistency of the results obtained from the point-splitting thermal stress tensor in the case of the Rindler space are pointed out.

  1. PROCESS OF IDENTIFYING COMPETENCIES BASED ON A FUNCTIONAL APPROACH

    Directory of Open Access Journals (Sweden)

    NAOUFAL SEFIANI

    2012-01-01

    Full Text Available To cope with fast change of the technological and organizational context, managers need tools to help them to improve competence management. Our contribution aims at supporting the task of competence identification that is considered as the first step of the management process. The proposed identification involves tree stages.The first stage concerns the research of competences based on a functional approach. The second stage is to define a typology of the component of competence (characterization and the third stage to define the core competencies of competence (prioritization. The application of the method in an industrial case in the logisticsfield confirms the possibility of using the “principle of solution” to provide a dynamic process for the identification of requisite competencies.

  2. A transfer function approach to measuring cell inheritance

    Directory of Open Access Journals (Sweden)

    Errington Rachel J

    2011-02-01

    Full Text Available Abstract Background The inheritance of cellular material between parent and daughter cells during mitosis is highly influential in defining the properties of the cell and therefore the population lineage. This is of particular relevance when studying cell population evolution to assess the impact of a disease or the perturbation due to a drug treatment. The usual technique to investigate inheritance is to use time-lapse microscopy with an appropriate biological marker, however, this is time consuming and the number of inheritance events captured are too low to be statistically meaningful. Results Here we demonstrate the use of a high throughput fluorescence measurement technique e.g. flow cytometry, to measure the fluorescence from quantum dot markers which can be used to target particular cellular sites. By relating, the fluorescence intensity measured between two time intervals to a transfer function we are able to deconvolve the inheritance of cellular material during mitosis. To demonstrate our methodology we use CdTe/ZnS quantum dots to measure the ratio of endosomes inherited by the two daughter cells during mitosis in the U2-OS, human osteoscarcoma cell line. The ratio determined is in excellent agreement with results obtained previously using a more complex and computational intensive bespoke stochastic model. Conclusions The use of a transfer function approach allows us to utilise high throughput measurement of large cell populations to derive statistically relevant measurements of the inheritance of cellular material. This approach can be used to measure the inheritance of organelles, proteins etc. and also particles introduced to cells for drug delivery.

  3. Distribution function approach to irreversible adsorption of interacting colloidal particles

    Science.gov (United States)

    Faraudo, Jordi; Bafaluy, Javier

    2000-01-01

    A statistical-mechanical description of the irreversible adsorption of interacting colloidal particles is developed. Our approach describes in a consistent way the interaction of particles from the bulk with adsorbed particles during the transport process towards the adsorbing surface. The macroscopic physical quantities corresponding to the actual process are expressed as averages over simpler auxiliary processes which proceed in the presence of a fixed number n of adsorbed particles. The adsorption rate verifies a generalized Langmuir equation, in which the kinetic resistance (the inverse of the kinetic coefficient) is expressed as the sum of a diffusional resistance and a resistance due to interaction with adsorbed particles during the transport process (blocking effect). Contrary to previous approaches, the blocking effect is not due to geometrical exclusion, instead it measures how the transport from the bulk is affected by the adsorbed particles. From the general expressions obtained, we have derived coverage expansions for the adsorption rate and the surface correlation function. The theory is applied to the case of colloidal particles interacting through DLVO potentials. This form of the kinetic coefficient is shown to be in agreement with recent experimental results, in which RSA fails.

  4. Predicting activity approach based on new atoms similarity kernel function.

    Science.gov (United States)

    Abu El-Atta, Ahmed H; Moussa, M I; Hassanien, Aboul Ella

    2015-07-01

    Drug design is a high cost and long term process. To reduce time and costs for drugs discoveries, new techniques are needed. Chemoinformatics field implements the informational techniques and computer science like machine learning and graph theory to discover the chemical compounds properties, such as toxicity or biological activity. This is done through analyzing their molecular structure (molecular graph). To overcome this problem there is an increasing need for algorithms to analyze and classify graph data to predict the activity of molecules. Kernels methods provide a powerful framework which combines machine learning with graph theory techniques. These kernels methods have led to impressive performance results in many several chemoinformatics problems like biological activity prediction. This paper presents a new approach based on kernel functions to solve activity prediction problem for chemical compounds. First we encode all atoms depending on their neighbors then we use these codes to find a relationship between those atoms each other. Then we use relation between different atoms to find similarity between chemical compounds. The proposed approach was compared with many other classification methods and the results show competitive accuracy with these methods.

  5. Convergent approaches for defining functional imaging endophenotypes in schizophrenia

    Directory of Open Access Journals (Sweden)

    Godfrey Pearlson

    2009-11-01

    Full Text Available In complex genetic disorders such as schizophrenia, endophenotypes have potential utility both in identifying risk genes and in illuminating pathophysiology. This is due to their presumed status as closer in the etiopathological pathway to the causative genes than is the currently defining clinical phenomenology of the illness and thus their simpler genetic architecture than that of the full syndrome. There, many genes conferring slight individual risk are additive or epistatic (interactive with regard to cumulative schizophrenia risk. In addition the use of endophenotypes has encouraged a conceptual shift away from the exclusive study of categorical diagnoses in manifestly ill patients, towards the study of quantitative traits in patients, unaffected relatives and healthy controls. A more recently employed strategy is thus to study unaffected first degree relatives of schizophrenia patients, who share some of the genetic diathesis without illness-related confounds that may themselves impact fMRI task performance. Consistent with the multiple biological abnormalities associated with the disorder, many candidate endophenotypes have been advanced for schizophrenia, including measures derived from structural brain imaging, EEG, sensorimotor integration, eye movements and cognitive performance (Allen 2009, but recent data derived from quantitative functional brain imaging measures present additional attractive putative endophenotypes. We will review two major, conceptually different approaches that use fMRI in this context. One, the dominant paradigm, employs defined cognitive tasks on which schizophrenia patients perform poorly as “cognitive stress tests”. The second uses very simple probes or “task-free” approaches where performance in patients and controls is equal. We explore the potential advantages and disadvantages of each method, the associated data analytic approaches and recent studies exploring their interface with the genetic

  6. Band alignment and chemical bonding at the GaAs/Al{sub 2}O{sub 3} interface: A hybrid functional study

    Energy Technology Data Exchange (ETDEWEB)

    Colleoni, Davide, E-mail: davide.colleoni@epfl.ch; Miceli, Giacomo; Pasquarello, Alfredo [Chaire de Simulation à l' Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2015-11-23

    The band alignment at the interface between GaAs and amorphous Al{sub 2}O{sub 3} is studied through the use of hybrid functionals. For the oxide component, a disordered model is generated through density-functional molecular dynamics. The achieved structure shows good agreement with the experimental characterization. The potential line-up across the interface is obtained for two atomistic GaAs/Al{sub 2}O{sub 3} interface models, which differ by the GaAs substrate termination. The calculated valence band offset amounts to 3.9 eV for an interface characterized by the occurrence of Ga–O bonds as dominant chemical bonding, favoring the high-energy side in the range of experimental values (2.6–3.8 eV). The effect of As antisite and As–As dimer defects on the band alignment is shown to be negligible.

  7. Molecular Approaches to Functionalization of Dental Implant Surfaces

    Directory of Open Access Journals (Sweden)

    Angelina O. Zekiy

    2015-12-01

    Full Text Available The present review examines several approaches to improve properties of dental implants by modifying their bioactive surfaces (functionalization using the techniques of molecular transplantation. The first group of functional ligands is designed to enhance osseointegration of implants, it includes growth factors, promoting the formation and bone remodeling: bone morphogenetic proteins (BMPs, platelet-derived growth factor (PDGF, fibroblast growth factor (FGF and their combinations with each other, and several other ones. The second group of bioactive molecules does not directly stimulate bone formation, but it promotes osteoblast seeding on the implant surface due to the adhesive properties, thus accelerating osseointegration. Finally, the third group of substances used to increase the antibacterial properties of coatings, thereby reducing the formation of bacterial film on the implant surface and the risk of inflammatory rejection of the implant. Key issues of using biofunctional coatings, despite their obvious promise today still are relatively high cost, difficulties of controlling properties and its storage between the fabrication and installation of implants in the bone of the recipient.

  8. A Model-Based Approach to Constructing Music Similarity Functions

    Directory of Open Access Journals (Sweden)

    Lamere Paul

    2007-01-01

    Full Text Available Several authors have presented systems that estimate the audio similarity of two pieces of music through the calculation of a distance metric, such as the Euclidean distance, between spectral features calculated from the audio, related to the timbre or pitch of the signal. These features can be augmented with other, temporally or rhythmically based features such as zero-crossing rates, beat histograms, or fluctuation patterns to form a more well-rounded music similarity function. It is our contention that perceptual or cultural labels, such as the genre, style, or emotion of the music, are also very important features in the perception of music. These labels help to define complex regions of similarity within the available feature spaces. We demonstrate a machine-learning-based approach to the construction of a similarity metric, which uses this contextual information to project the calculated features into an intermediate space where a music similarity function that incorporates some of the cultural information may be calculated.

  9. ABOUT COMPLEX APPROACH TO MODELLING OF TECHNOLOGICAL MACHINES FUNCTIONING

    Directory of Open Access Journals (Sweden)

    A. A. Honcharov

    2015-01-01

    Full Text Available Problems arise in the process of designing, production and investigation of a complicated technological machine. These problems concern not only properties of some types of equipment but they have respect to regularities of control object functioning as a whole. A technological machine is thought of as such technological complex where it is possible to lay emphasis on a control system (or controlling device and a controlled object. The paper analyzes a number of existing approaches to construction of models for controlling devices and their functioning. A complex model for a technological machine operation has been proposed in the paper; in other words it means functioning of a controlling device and a controlled object of the technological machine. In this case models of the controlling device and the controlled object of the technological machine can be represented as aggregate combination (elements of these models. The paper describes a conception on realization of a complex model for a technological machine as a model for interaction of units (elements in the controlling device and the controlled object. When a control activation is given to the controlling device of the technological machine its modelling is executed at an algorithmic or logic level and the obtained output signals are interpreted as events and information about them is transferred to executive mechanisms.The proposed scheme of aggregate integration considers element models as object classes and the integration scheme is presented as a combination of object property values (combination of a great many input and output contacts and combination of object interactions (in the form of an integration operator. Spawn of parent object descendants of the technological machine model and creation of their copies in various project parts is one of the most important means of the distributed technological machine modelling that makes it possible to develop complicated models of

  10. Functional Associations by Response Overlap (FARO), a functional genomics approach matching gene expression phenotypes

    DEFF Research Database (Denmark)

    Nielsen, Henrik Bjørn; Mundy, J.; Willenbrock, Hanni

    2007-01-01

    The systematic comparison of transcriptional responses of organisms is a powerful tool in functional genomics. For example, mutants may be characterized by comparing their transcript profiles to those obtained in other experiments querying the effects on gene expression of many experimental factors...... for deriving 'Functional Association(s) by Response Overlap' (FARO) between microarray gene expression studies. The transcriptional response is defined by the set of differentially expressed genes independent from the magnitude or direction of the change. This approach overcomes the limited comparability...... to confirm and further delineate the functions of Arabidopsis MAP kinase 4 in disease and stress responses. Furthermore, we find that a large, well-defined set of genes responds in opposing directions to different stress conditions and predict the effects of different stress combinations. This demonstrates...

  11. Complex esthetic and functional rehabilitation with an additive, minimally invasive restorative approach.

    Science.gov (United States)

    Ho, Christopher Ck

    2014-06-01

    Historically, the management of patients presenting with extensive tooth wear comprised the use of conventional fixed prosthodontics, an approach that often entailed invasive dentistry and increased biomechanical risk. With the development of adhesive bonding, a dentition can be restored in a much more conservative manner using an additive approach. This case report describes the concepts employed in a complex rehabilitation involving tooth erosion, applying both direct and indirect restorations with minimal biological risk to the patient.

  12. Adsorptive Removal of Pharmaceuticals and Personal Care Products from Water with Functionalized Metal-organic Frameworks: Remarkable Adsorbents with Hydrogen-bonding Abilities

    Science.gov (United States)

    Seo, Pill Won; Bhadra, Biswa Nath; Ahmed, Imteaz; Khan, Nazmul Abedin; Jhung, Sung Hwa

    2016-01-01

    Adsorption of typical pharmaceuticals and personal care products (PPCPs) (such as naproxen, ibuprofen and oxybenzone) from aqueous solutions was studied by using the highly porous metal-organic framework (MOF) MIL-101 with and without functionalization. Adsorption results showed that MIL-101s with H-donor functional groups such as –OH and –NH2 were very effective for naproxen adsorption, despite a decrease in porosity, probably because of H-bonding between O atoms on naproxen and H atoms on the adsorbent. For this reason, MIL-101 with two functional groups capable of H-bonding (MIL-101-(OH)2) exhibited remarkable adsorption capacity based on adsorbent surface area. The favorable contributions of –OH and –(OH)2 on MIL-101 in the increased adsorption of ibuprofen and oxybenzone (especially based on porosity) confirmed again the importance of H-bonding mechanism. The adsorbent with the highest adsorption capacity, MIL-101-OH, was very competitive when compared with carbonaceous materials, mesoporous materials, and pristine MIL-101. Moreover, the MIL-101-OH could be recycled several times by simply washing with ethanol, suggesting potential application in the adsorptive removal of PPCPs from water. PMID:27695005

  13. Molecular dynamics simulations of the hydration of poly(vinyl methyl ether): Hydrogen bonds and quasi-hydrogen bonds

    Institute of Scientific and Technical Information of China (English)

    WU RongLiang; JI Qing; KONG Bin; YANG XiaoZhen

    2008-01-01

    Atomistic detailed hydration structures of poly(vinyl methyl ether) (PVME) have been investigated by molecular dynamics simulations under 300 K at various concentrations. Both radial distribution func-tions and the distance distributions between donors and acceptors in hydrogen bonds show that the hydrogen bonds between the polymer and water are shorter by 0.005 nm than those between water molecules. The Quasi-hydrogen bonds take only 7.2% of the van der Waals interaction pairs. It was found the hydrogen bonds are not evenly distributed along the polymer chain, and there still exists a significant amount (10%) of ether oxygen atoms that are not hydrogen bonded to water at a concentra-tion as low as 3.3%. This shows that in polymer solutions close contacts occur not only between polymer chains but also between chain segments within the polymer, which leads to inefficient con-tacts between ether oxygen atoms and water molecules. Variation of the quasi-hydrogen bonds with the concentration is similar to that of hydrogen bonds, but the ratio of the repeat units forming quasi-hydrogen bonds to those forming hydrogen bonds approaches 0.2. A transition was found in the demixing enthalpy at around 30% measured by dynamic testing differential scanning calorimetry (DTDSC) for aqueous solutions of a mono-dispersed low molecular weight PVME, which can be related to the transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27%. The transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27% can be used to explain the demixing enthalpy transition at 30% at a molecular scale. In addition, at the concentration of 86%, each ether oxygen atom bonded with water is assigned 1.56 water molecules on average, and 'free' water molecules emerge at the concentration of around 54%.

  14. Molecular dynamics simulations of the hydration of poly(vinyl methyl ether):Hydrogen bonds and quasi-hydrogen bonds

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Atomistic detailed hydration structures of poly(vinyl methyl ether)(PVME) have been investigated by molecular dynamics simulations under 300 K at various concentrations. Both radial distribution functions and the distance distributions between donors and acceptors in hydrogen bonds show that the hydrogen bonds between the polymer and water are shorter by 0.005 nm than those between water molecules. The Quasi-hydrogen bonds take only 7.2% of the van der Waals interaction pairs. It was found the hydrogen bonds are not evenly distributed along the polymer chain,and there still exists a significant amount(10%) of ether oxygen atoms that are not hydrogen bonded to water at a concentration as low as 3.3%. This shows that in polymer solutions close contacts occur not only between polymer chains but also between chain segments within the polymer,which leads to inefficient contacts between ether oxygen atoms and water molecules. Variation of the quasi-hydrogen bonds with the concentration is similar to that of hydrogen bonds,but the ratio of the repeat units forming quasi-hydrogen bonds to those forming hydrogen bonds approaches 0.2. A transition was found in the demixing enthalpy at around 30% measured by dynamic testing differential scanning calorimetry(DTDSC) for aqueous solutions of a mono-dispersed low molecular weight PVME,which can be related to the transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27%. The transition of the fractions of hydrogen bonds and quasi-hydrogen bonds at ~27% can be used to explain the demixing enthalpy transition at 30% at a molecular scale. In addition,at the concentration of 86%,each ether oxygen atom bonded with water is assigned 1.56 water molecules on average,and ’free’ water molecules emerge at the concentration of around 54%.

  15. Geometry of trigonal boron coordination sphere in boronic acids derivatives - a bond-valence vector model approach.

    Science.gov (United States)

    Czerwińska, Karolina; Madura, Izabela D; Zachara, Janusz

    2016-04-01

    The systematic analysis of the geometry of three-coordinate boron in boronic acid derivatives with a common [CBO2] skeleton is presented. The study is based on the bond-valence vector (BVV) model [Zachara (2007). Inorg. Chem. 46, 9760-9767], a simple tool for the identification and quantitative estimation of both steric and electronic factors causing deformations of the coordination sphere. The empirical bond-valence (BV) parameters in the exponential equation [Brown & Altermatt (1985). Acta Cryst. B41, 244-247] rij and b, for B-O and B-C bonds were determined using data deposited in the Cambridge Structural Database. The values obtained amount to rBO = 1.364 Å, bBO = 0.37 Å, rBC = 1.569 Å, bBC = 0.28 Å, and they were further used in the calculation of BVV lengths. The values of the resultant BVV were less than 0.10 v.u. for 95% of the set comprising 897 [CBO2] fragments. Analysis of the distribution of BVV components allowed for the description of subtle in- and out-of plane deviations from the `ideal' (sp(2)) geometry of boron coordination sphere. The distortions specific for distinct groups of compounds such as boronic acids, cyclic and acyclic esters, benzoxaboroles and hemiesters were revealed. In cyclic esters the direction of strains was found to be controlled by the ring size effect. It was shown that the syn or anti location of substituents on O atoms is decisive for the deformations direction for both acids and acyclic esters. The greatest strains were observed in the case of benzoxaboroles which showed the highest deviation from the zero value of the resultant BVV. The out-of-plane distortions, described by the vz component of the resultant BVV, were ascertained to be useful in the identification of weak secondary interactions on the fourth coordination site of the boron centre. PMID:27048726

  16. Chebyshev matrix product state approach for spectral functions

    Science.gov (United States)

    Holzner, Andreas; Weichselbaum, Andreas; McCulloch, Ian P.; Schollwöck, Ulrich; von Delft, Jan

    2011-05-01

    We show that recursively generated Chebyshev expansions offer numerically efficient representations for calculating zero-temperature spectral functions of one-dimensional lattice models using matrix product state (MPS) methods. The main features of this Chebyshev matrix product state (CheMPS) approach are as follows: (i) it achieves uniform resolution over the spectral function’s entire spectral width; (ii) it can exploit the fact that the latter can be much smaller than the model’s many-body bandwidth; (iii) it offers a well-controlled broadening scheme that allows finite-size effects to be either resolved or smeared out, as desired; (iv) it is based on using MPS tools to recursively calculate a succession of Chebyshev vectors |tn>, (v) the entanglement entropies of which were found to remain bounded with increasing recursion order n for all cases analyzed here; and (vi) it distributes the total entanglement entropy that accumulates with increasing n over the set of Chebyshev vectors |tn>, which need not be combined into a single vector. In this way, the growth in entanglement entropy that usually limits density matrix renormalization group (DMRG) approaches is packaged into conveniently manageable units. We present zero-temperature CheMPS results for the structure factor of spin-(1)/(2) antiferromagnetic Heisenberg chains and perform a detailed finite-size analysis. Making comparisons to three benchmark methods, we find that CheMPS (a) yields results comparable in quality to those of correction-vector DMRG, at dramatically reduced numerical cost; (b) agrees well with Bethe ansatz results for an infinite system, within the limitations expected for numerics on finite systems; and (c) can also be applied in the time domain, where it has potential to serve as a viable alternative to time-dependent DMRG (in particular, at finite temperatures). Finally, we present a detailed error analysis of CheMPS for the case of the noninteracting resonant level model.

  17. VB studies on bonding features of HNC(←→)HCN

    Institute of Scientific and Technical Information of China (English)

    廖新丽; 吴玮; 莫亦荣; 张乾二

    2003-01-01

    Within the bonded tableau unitary group approach (BTUGA), a scheme, combined with Pauling's resonance theory to select the predominant valence bond structures for VB calculations, is proposed. This scheme ensures a reliable and illustrative bonding picture in the description of chemical reactions, as exemplified by the isomerization reaction HNCHCN. The computation results account for important bonding features about this isomerization at the ab initio level and explore the mechanism of phenomena such as (i) HCN is more stable than HNC; (ii) the C-N bond first lengthens and then shortens in the vicinity of the transition state; (iii) only H-atom migration is observed in the isomerization process, without the breaking of the CN bond. Our results demonstrate that only a few bonded tableau functions are sufficient enough to provide a visual and reliable bonding picture.

  18. Number series of atoms, interatomic bonds and interface bonds defining zinc-blende nanocrystals as function of size, shape and surface orientation: Analytic tools to interpret solid state spectroscopy data

    Directory of Open Access Journals (Sweden)

    Dirk König

    2016-08-01

    Full Text Available Semiconductor nanocrystals (NCs experience stress and charge transfer by embedding materials or ligands and impurity atoms. In return, the environment of NCs experiences a NC stress response which may lead to matrix deformation and propagated strain. Up to now, there is no universal gauge to evaluate the stress impact on NCs and their response as a function of NC size dNC. I deduce geometrical number series as analytical tools to obtain the number of NC atoms NNC(dNC[i], bonds between NC atoms Nbnd(dNC[i] and interface bonds NIF(dNC[i] for seven high symmetry zinc-blende (zb NCs with low-index faceting: {001} cubes, {111} octahedra, {110} dodecahedra, {001}-{111} pyramids, {111} tetrahedra, {111}-{001} quatrodecahedra and {001}-{111} quadrodecahedra. The fundamental insights into NC structures revealed here allow for major advancements in data interpretation and understanding of zb- and diamond-lattice based nanomaterials. The analytical number series can serve as a standard procedure for stress evaluation in solid state spectroscopy due to their deterministic nature, easy use and general applicability over a wide range of spectroscopy methods as well as NC sizes, forms and materials.

  19. Number series of atoms, interatomic bonds and interface bonds defining zinc-blende nanocrystals as function of size, shape and surface orientation: Analytic tools to interpret solid state spectroscopy data

    Science.gov (United States)

    König, Dirk

    2016-08-01

    Semiconductor nanocrystals (NCs) experience stress and charge transfer by embedding materials or ligands and impurity atoms. In return, the environment of NCs experiences a NC stress response which may lead to matrix deformation and propagated strain. Up to now, there is no universal gauge to evaluate the stress impact on NCs and their response as a function of NC size dNC. I deduce geometrical number series as analytical tools to obtain the number of NC atoms NNC(dNC[i]), bonds between NC atoms Nbnd(dNC[i]) and interface bonds NIF(dNC[i]) for seven high symmetry zinc-blende (zb) NCs with low-index faceting: {001} cubes, {111} octahedra, {110} dodecahedra, {001}-{111} pyramids, {111} tetrahedra, {111}-{001} quatrodecahedra and {001}-{111} quadrodecahedra. The fundamental insights into NC structures revealed here allow for major advancements in data interpretation and understanding of zb- and diamond-lattice based nanomaterials. The analytical number series can serve as a standard procedure for stress evaluation in solid state spectroscopy due to their deterministic nature, easy use and general applicability over a wide range of spectroscopy methods as well as NC sizes, forms and materials.

  20. The unique functional role of the C-HS hydrogen bond in the substrate specificity and enzyme catalysis of type 1 methionine aminopeptidase.

    Science.gov (United States)

    Reddi, Ravikumar; Singarapu, Kiran Kumar; Pal, Debnath; Addlagatta, Anthony

    2016-07-19

    It is intriguing how nature attains recognition specificity between molecular interfaces where there is no apparent scope for classical hydrogen bonding or polar interactions. Methionine aminopeptidase (MetAP) is one such enzyme where this fascinating conundrum is at play. In this study, we demonstrate that a unique C-HS hydrogen bond exists between the enzyme methionine aminopeptidase (MetAP) and its N-terminal-methionine polypeptide substrate, which allows specific interaction between apparent apolar interfaces, imposing a strict substrate recognition specificity and efficient catalysis, a feature replicated in Type I MetAPs across all kingdoms of life. We evidence this evolutionarily conserved C-HS hydrogen bond through enzyme assays on wild-type and mutant MetAP proteins from Mycobacterium tuberculosis that show a drastic difference in catalytic efficiency. The X-ray crystallographic structure of the methionine bound protein revealed a conserved water bridge and short contacts involving the Met side-chain, a feature also observed in MetAPs from other organisms. Thermal shift assays showed a remarkable 3.3 °C increase in melting temperature for methionine bound protein compared to its norleucine homolog, where C-HS interaction is absent. The presence of C-HS hydrogen bonding was also corroborated by nuclear magnetic resonance spectroscopy through a change in chemical shift. Computational chemistry studies revealed the unique role of the electrostatic environment in facilitating the C-HS interaction. The significance of this atypical hydrogen bond is underscored by the fact that the function of MetAP is essential for any living cell. PMID:27225936

  1. Exponential wealth distribution : a new approach from functional iteration theory*

    Directory of Open Access Journals (Sweden)

    López José-Luis

    2012-08-01

    Full Text Available Different approaches are possible in order to derive the exponential regime in statistical systems. Here, a new functional equation is proposed in an economic context to explain the wealth exponential distribution. Concretely, the new iteration [1] given by egin{equation} f_{n+1}(x = int!!int_{u+v>x},{f_n(uf_n(vover u+v} ; {mathrm d}u{mathrm d}v ,. onumber label{syst1} end{equation} f n + 1 ( x = ∫ ∫ u + v > x   f n ( u f n ( v u + v d u d v   . It is found that the exponential distribution is a stable fixed point of this functional iteration equation. From this point of view, it is easily understood why the exponential wealth distribution (or by extension, other kind of distributions is asymptotically obtained in different multi-agent economic models. Différentes approches pour dériver le régime asymptotique exponentiel dans les systèmes statistiques sont possibles. Ici une nouvelle équation fonctionnelle est proposée, dans le cadre des systèmes économiques, pour expliquer la distribution exponentielle. Nous montrons que cette distribution est le seul point fixe vers lequel la dynamique de cette équation fonctionnelle évolue quand l’itération va vers l’infini. De ce point de vue, il est facile de comprendre l’ubiquité de cette distribution (ou d’autres en différents problèmes statistiques réels.

  2. Polymicrobial Multi-functional Approach for Enhancement of Crop Productivity.

    Science.gov (United States)

    Reddy, Chilekampalli A; Saravanan, Ramu S

    2013-01-01

    There is an increasing global need for enhancing the food production to meet the needs of the fast-growing human population. Traditional approach to increasing agricultural productivity through high inputs of chemical nitrogen and phosphate fertilizers and pesticides is not sustainable because of high costs and concerns about global warming, environmental pollution, and safety concerns. Therefore, the use of naturally occurring soil microbes for increasing productivity of food crops is an attractive eco-friendly, cost-effective, and sustainable alternative to the use of chemical fertilizers and pesticides. There is a vast body of published literature on microbial symbiotic and nonsymbiotic nitrogen fixation, multiple beneficial mechanisms used by plant growth-promoting rhizobacteria (PGPR), the nature and significance of mycorrhiza-plant symbiosis, and the growing technology on production of efficacious microbial inoculants. These areas are briefly reviewed here. The construction of an inoculant with a consortium of microbes with multiple beneficial functions such as N(2) fixation, biocontrol, phosphate solubilization, and other plant growth-promoting properties is a positive new development in this area in that a single inoculant can be used effectively for increasing the productivity of a broad spectrum of crops including legumes, cereals, vegetables, and grasses. Such a polymicrobial inoculant containing several microorganisms for each major function involved in promoting the plant growth and productivity gives it greater stability and wider applications for a range of major crops. Intensifying research in this area leading to further advances in our understanding of biochemical/molecular mechanisms involved in plant-microbe-soil interactions coupled with rapid advances in the genomics-proteomics of beneficial microbes should lead to the design and development of inoculants with greater efficacy for increasing the productivity of a wide range of crops.

  3. Executive Function and Food Approach Behavior in Middle Childhood

    Directory of Open Access Journals (Sweden)

    Karoline eGroppe

    2014-05-01

    Full Text Available Executive function (EF has long been considered to be a unitary, domain-general cognitive ability. However, recent research suggests differentiating ‘hot’ affective and ‘cool’ cognitive aspects of EF. Yet, findings regarding this two-factor construct are still inconsistent. In particular, the development of this factor structure remains unclear and data on school-aged children is lacking. Furthermore, studies linking EF and overweight or obesity suggest that EF contributes to the regulation of eating behavior. So far, however, the links between EF and eating behavior have rarely been investigated in children and non-clinical populations.First, we examined whether EF can be divided into hot and cool factors or whether they actually correspond to a unitary construct in middle childhood. Second, we examined how hot and cool EF are associated with different eating styles that put children at risk of becoming overweight during development. Hot and cool EF were assessed experimentally in a non-clinical population of 1,657 elementary-school children (aged 6-11 years. The ‘food approach’ behavior was rated mainly via parent questionnaires.Findings indicate that hot EF is distinguishable from cool EF. However, only cool EF seems to represent a coherent functional entity, whereas hot EF does not seem to be a homogenous construct. This was true for a younger and an older subgroup of children. Furthermore, different EF components were correlated with eating styles, such as responsiveness to food, desire to drink, and restrained eating in girls but not in boys. This shows that lower levels of EF are not only seen in clinical populations of obese patients but are already associated with food approach styles in a normal population of elementary school-aged girls. Although the direction of effect still has to be clarified, results point to the possibility that EF constitutes a risk factor for eating styles contributing to the development of

  4. The structure and function of the first component of complement: genetic engineering approach (a review).

    Science.gov (United States)

    Gál, P; Cseh, S; Schumaker, V N; Závodszky, P

    1994-01-01

    The availability of cDNA and genomic clones for the subcomponents of C1, as well as the recognition of the modular organization of serine-proteases have opened up exciting new possibilities for approaching structural problems. In this review the latest achievements of combined protein engineering, functional and structural studies are summarized. The concept of this research is to construct deletion, point and hybrid mutants of the highly homologous C1r and C1s subcomponents, to reveal the functional role of individual modules, map the interaction sites between subcomponents of the C1 complex and refine the structural model of C1. The first prerequisite of such an approach was the expression of the subcomponents in a eukaryotic system, in biologically active form. This was followed by expression of various mutants. Autographa californica nuclear polyhedrosis virus was used as vector to express human C1r and C1s in Spodoptera frugiperda cell culture and in lepidopteran larvae. The yield of expression was high enough to isolate recombinant subcomponents for structural and functional studies. Recombinant viruses containing the A-, B-, and C-chains of C1q were also constructed. The insect cells are able to beta-hydroxylate the Asn residue of the EGF domain in the C1r but with a low efficiency. It is clear now, that this post-translational modification does not play a role in the Ca2+ dependent C1r-C1s interaction. The results with deletion mutants of C1r show that both, domain I, and II are absolutely necessary for the tetramer formation and both have regulatory role in the autoactivation. The C1s alpha R hybrid does not dimerize in presence of Ca2+, however it can form a tetramer with C11(2) that can bind to C1q. This observation indicates that the function of the C1s alpha part in the hybrid is modulated by the C1r part (gamma B) of the molecule. The C1Rs hybrid behaves like C1r, providing haemolytically active C1 with C1q and C1s. This observations shows that the

  5. Selectionist and evolutionary approaches to brain function: a critical appraisal

    Directory of Open Access Journals (Sweden)

    Chrisantha Thomas Fernando

    2012-04-01

    Full Text Available We consider approaches to brain dynamics and function that have been claimed to be Darwinian. These include Edelman’s theory of neuronal group selection, Changeux’s theory of synaptic selection and selective stabilization of pre-representations, Seung’s Darwinian synapse, Loewenstein’s synaptic melioration, Adam’s selfish synapse and Calvin’s replicating activity patterns. Except for the last two, the proposed mechanisms are selectionist but not truly Darwinian, because no replicators with information transfer to copies and hereditary variation can be identified in them. All of them fit, however, a generalized selectionist framework conforming to the picture of Price’s covariance formulation, which deliberately was not specific even to selection in biology, and therefore does not imply an algorithmic picture of biological evolution. Bayesian models and reinforcement learning are formally in agreement with selection dynamics. A classification of search algorithms is shown to include Darwinian replicators (evolutionary units with multiplication, heredity and variability as the most powerful mechanism in a sparsely occupied search space. Examples of why parallel competitive search with information transfer among the units is efficient are given. Finally, we review our recent attempts to construct and analyze simple models of true Darwinian evolutionary units in the brain in terms of connectivity and activity copying of neuronal groups. Although none of the proposed neuronal replicators include miraculous mechanisms, their identification remains a challenge but also a great promise.

  6. A new Bayesian approach to the reconstruction of spectral functions

    CERN Document Server

    Burnier, Yannis

    2013-01-01

    We present a novel approach for the reconstruction of spectra from Euclidean correlator data that makes close contact to modern Bayesian concepts. It is based upon an axiomatically justified dimensionless prior distribution, which in the case of constant prior function $m(\\omega)$ only imprints smoothness on the reconstructed spectrum. In addition we are able to analytically integrate out the only relevant overall hyper-parameter $\\alpha$ in the prior, removing the necessity for Gaussian approximations found e.g. in the Maximum Entropy Method. Using a quasi-Newton minimizer and high-precision arithmetic, we are then able to find the unique global extremum of $P[\\rho|D]$ in the full $N_\\omega\\gg N_\\tau$ dimensional search space. The method actually yields gradually improving reconstruction results if the quality of the supplied input data increases, without introducing artificial peak structures, often encountered in the MEM. To support these statements we present mock data analyses for the case of zero width ...

  7. Excitation energies with linear response density matrix functional theory along the dissociation coordinate of an electron-pair bond in N-electron systems.

    Science.gov (United States)

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

    2014-01-14

    Time dependent density matrix functional theory in its adiabatic linear response formulation delivers exact excitation energies ωα and oscillator strengths fα for two-electron systems if extended to the so-called phase including natural orbital (PINO) theory. The Löwdin-Shull expression for the energy of two-electron systems in terms of the natural orbitals and their phases affords in this case an exact phase-including natural orbital functional (PILS), which is non-primitive (contains other than just J and K integrals). In this paper, the extension of the PILS functional to N-electron systems is investigated. With the example of an elementary primitive NO functional (BBC1) it is shown that current density matrix functional theory ground state functionals, which were designed to produce decent approximations to the total energy, fail to deliver a qualitatively correct structure of the (inverse) response function, due to essential deficiencies in the reconstruction of the two-body reduced density matrix (2RDM). We now deduce essential features of an N-electron functional from a wavefunction Ansatz: The extension of the two-electron Löwdin-Shull wavefunction to the N-electron case informs about the phase information. In this paper, applications of this extended Löwdin-Shull (ELS) functional are considered for the simplest case, ELS(1): one (dissociating) two-electron bond in the field of occupied (including core) orbitals. ELS(1) produces high quality ωα(R) curves along the bond dissociation coordinate R for the molecules LiH, Li2, and BH with the two outer valence electrons correlated. All of these results indicate that response properties are much more sensitive to deficiencies in the reconstruction of the 2RDM than the ground state energy, since derivatives of the functional with respect to both the NOs and the occupation numbers need to be accurate. PMID:24437859

  8. Filtered density function approach for reactive transport in groundwater

    Science.gov (United States)

    Suciu, Nicolae; Schüler, Lennart; Attinger, Sabine; Knabner, Peter

    2016-04-01

    Spatial filtering may be used in coarse-grained simulations (CGS) of reactive transport in groundwater, similar to the large eddy simulations (LES) in turbulence. The filtered density function (FDF), stochastically equivalent to a probability density function (PDF), provides a statistical description of the sub-grid, unresolved, variability of the concentration field. Besides closing the chemical source terms in the transport equation for the mean concentration, like in LES-FDF methods, the CGS-FDF approach aims at quantifying the uncertainty over the whole hierarchy of heterogeneity scales exhibited by natural porous media. Practically, that means estimating concentration PDFs on coarse grids, at affordable computational costs. To cope with the high dimensionality of the problem in case of multi-component reactive transport and to reduce the numerical diffusion, FDF equations are solved by particle methods. But, while trajectories of computational particles are modeled as stochastic processes indexed by time, the concentration's heterogeneity is modeled as a random field, with multi-dimensional, spatio-temporal sets of indices. To overcome this conceptual inconsistency, we consider FDFs/PDFs of random species concentrations weighted by conserved scalars and we show that their evolution equations can be formulated as Fokker-Planck equations describing stochastically equivalent processes in concentration-position spaces. Numerical solutions can then be approximated by the density in the concentration-position space of an ensemble of computational particles governed by the associated Itô equations. Instead of sequential particle methods we use a global random walk (GRW) algorithm, which is stable, free of numerical diffusion, and practically insensitive to the increase of the number of particles. We illustrate the general FDF approach and the GRW numerical solution for a reduced complexity problem consisting of the transport of a single scalar in groundwater

  9. Properties and structure of the functional composite materials - Nd-Fe-Co-B powder bonded with polymer

    Directory of Open Access Journals (Sweden)

    B. Ziębowicz

    2011-12-01

    Full Text Available Purpose: This paper presents the material and technological solution which makes it possible obtaining functional composite materials based on the nanocrystalline Nd-Fe-Co-B powder with polymer matrix and shows the possibility of application in different branches of the techniques.Design/methodology/approach: For fabrication of composite materials: Nd-Fe-Co-B powder obtained by rapid quenched technique and for matrix - high density pressureless polyethylene (PEHD and polyamide (PA12 (2.5 % wt. were used. Composite materials were compacted by the one-sided uniaxial pressing. The complex relationships among the manufacturing technology of these materials, their microstructure, as well as their mechanical and physical properties were evaluated. Materialographic examination of the structure of composite materials and fractures after decohesion were made.Findings: The main purpose of obtaining this kind of composite materials is broadening possibilities of nanocrystalline magnetic materials application that influence on the miniaturization, simplification and lowering the costs of devices. Composite materials show regular distribution of magnetic powder in polymer matrix. Examination of mechanical properties show that these materials have satisfactory compression strength.Practical implications: The manufacturing of composite materials Nd-Fe-Co-B powder – polymer greatly expand the applicable possibilities of nanocrystalline powders of magnetically hard materials however further examination to obtain improved properties of magnetic composite materials and investigations of constructions of new machines and devices with these materials elements are still needed.Originality/value: Manufacturing processes of functional composite materials obtaining Nd-Fe-Co-B – polymer matrix and determination of their mechanical properties. Results are the base for further investigations such composite materials.

  10. Reactive force field simulation of proton diffusion in BaZrO{sub 3} using an empirical valence bond approach

    Energy Technology Data Exchange (ETDEWEB)

    Raiteri, Paolo; Gale, Julian D [Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box 1987, Perth, WA 6845 (Australia); Bussi, Giovanni, E-mail: paolo@ivec.org, E-mail: julian@ivec.org [Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste (Italy)

    2011-08-24

    A new reactive force field to describe proton diffusion within the solid oxide fuel cell material BaZrO{sub 3} has been derived. Using a quantum mechanical potential energy surface, the parameters of an interatomic potential model to describe hydroxyl groups within both pure and yttrium-doped BaZrO{sub 3} have been determined. Reactivity is then incorporated through the use of the empirical valence bond model. Molecular dynamics simulations (EVB-MD) have been performed to explore the diffusion of hydrogen using a stochastic thermostat and barostat whose equations are extended to the isostress-isothermal ensemble. In the low concentration limit, the presence of yttrium is found not to significantly influence the diffusivity of hydrogen, despite the proton having a longer residence time at oxygen adjacent to the dopant. This lack of influence is due to the fact that trapping occurs infrequently, even when the proton diffuses through octahedra adjacent to the dopant. The activation energy for diffusion is found to be 0.42 eV, in good agreement with experimental values, though the prefactor is slightly underestimated.

  11. Supersymmetric Valence Bond Solid States

    OpenAIRE

    Arovas, Daniel P.; Hasebe, Kazuki; Qi, Xiao-Liang; Zhang, Shou-Cheng

    2009-01-01

    In this work we investigate the supersymmetric version of the valence bond solid (SVBS) state. In one dimension, the SVBS states continuously interpolate between the valence bond states for integer and half-integer spin chains, and they generally describe superconducting valence bond liquid states. Spin and superconducting correlation functions can be computed exactly for these states, and their correlation lengths are equal at the supersymmetric point. In higher dimensions, the wave function...

  12. 1, 4-Pyrone Effects on O-H Bond Dissociation Energies of Catechols in Flavonoids: A Density Functional Theory Study

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Through B3LYP/6-31G** calculations, the 1, 4-pyrone effects on O-H bond dissociation energies (BDEs) of catechols in rings A or B of flavonoids were investigated. For the catechol in ring A, although 1, 4-pyrone enlarged the conjugation system, its electron-withdrawing property increased the O-H BDE 3 ( 4.184 kJ/mol compared with that of catechol. However, for the catechol in ring B, 1, 4-pyrone was poorly conjugated with the moiety, and therefore, had little effect on the O-H BDE.

  13. Metatranscriptomic Approach to Analyze the Functional Human Gut Microbiota

    OpenAIRE

    Gosalbes, María José; Durbán, Ana; Pignatelli, Miguel; Abellan, Juan José; Jiménez-Hernández, Nuria; Pérez-Cobas, Ana Elena; Latorre, Amparo; Moya, Andrés

    2011-01-01

    The human gut is the natural habitat for a large and dynamic bacterial community that has a great relevance for health. Metagenomics is increasing our knowledge of gene content as well as of functional and genetic variability in this microbiome. However, little is known about the active bacteria and their function(s) in the gastrointestinal tract. We performed a metatranscriptomic study on ten healthy volunteers to elucidate the active members of the gut microbiome and their functionality und...

  14. Bond Boom

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The Ministry of Finance recently kick-started a pilot program allowing local governments of Shanghai and Shenzhen, and Zhejiang and Guangdong provinces to issue bonds for the first time. How will the new policy affect fiscal capacities of local governments and the broader economy? What else should the country do to build a healthy bond market? Economists and experts discussed these issues in an interview with the ShanghaiSecuritiesJournal. Edited excerpts follow:

  15. Bond Boom

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The Ministry of Finance recently kick-started a pilot program allowing local governments of Shanghai and Shenzhen,and Zhejiang and Guangdong provinces to issue bonds for the first time.How will the new policy affect fiscal capacities of local governments and the broader economy? What else should the country do to build a healthy bond market? Economists and experts discussed these issues in an interview with the Shanghai Securities Journal.Edited excerpts follow.

  16. Mayer Transfer Operator Approach to Selberg Zeta Function

    DEFF Research Database (Denmark)

    Momeni, Arash; Venkov, Alexei

    in terms of a Fredholm determinant of a classical transfer operator of the flow. The transfer operator is defined in a certain space of holomorphic functions and its matrix representation in a natural basis is given in terms of the Riemann zeta function and the Euler gamma function....

  17. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    The paper examines the role of structured bonds in the optimal portfolio of a small retail investor. We consider the typical structured bond essentially repacking an exotic option and a zero coupon bond, i.e. an investment with portfolio insurance. The optimal portfolio is found when the investment...... opportunities consist of a risky reference fund, a risk-free asset and a structured bond. Key model elements are the trading strategy and utility function of the investor. Our numerical results indicate structured bonds do have basis for consideration in the optimal portfolio. The product holdings...

  18. Force correcting atom centered potentials for generalized gradient approximated density functional theory: Approaching hybrid functional accuracy for geometries and harmonic frequencies in CCl$_3$F and other small molecules

    CERN Document Server

    von Lilienfeld, O Anatole

    2013-01-01

    Generalized gradient approximated (GGA) density functional theory (DFT) typically overestimates polarizability and bond-lengths, and underestimates force constants of covalent bonds. To overcome this problem we show that one can use empirical frequency correcting atom centered potentials (FCACPs), parameterized for every nuclear species. Parameters are obtained through minimization of a penalty functional that explicitly encodes hybrid DFT geometries and static polarizabilities of reference molecules. For hydrogen, fluorine, chlorine, and carbon the respective reference molecules consist of H$_2$, F$_2$, Cl$_2$, and CH$_4$. The transferability of this approach to other systems and properties is assessed for harmonic frequencies of a small set of molecules. Numerical evidence, gathered for CCl$_3$F, HF, HCl, CFH$_3$, and CHCl$_3$, indicates that the GGA+FCACP level of theory yields significantly improved harmonic frequencies at the desired hybrid DFT geometry minima, as well as systematically reduced molecular...

  19. Credit default swaps, bond spreads and the bond market

    OpenAIRE

    Zhu, Meicheng

    2014-01-01

    With the rapid development of the credit default swap (CDS) market, the issue of how the introduction of CDSs affects the corporate bond market has been of particular interest to researchers and policy makers. This has been investigated in the literature from two perspectives. One is to examine the relationship between the CDS and the bond markets in price discovery, and the other is concerned with researching the CDS trading effects on bond spreads. Referring to the former approach, most rel...

  20. Functional integral approach to the kinetic theory of inhomogeneous systems

    CERN Document Server

    Fouvry, Jean-Baptiste; Pichon, Christophe

    2016-01-01

    We present a derivation of the kinetic equation describing the secular evolution of spatially inhomogeneous systems with long-range interactions, the so-called inhomogeneous Landau equation, by relying on a functional integral formalism. We start from the BBGKY hierarchy derived from the Liouville equation. At the order ${1/N}$, where $N$ is the number of particles, the evolution of the system is characterised by its 1-body distribution function and its 2-body correlation function. Introducing associated auxiliary fields, the evolution of these quantities may be rewritten as a traditional functional integral. By functionally integrating over the 2-body autocorrelation, one obtains a new constraint connecting the 1-body DF and the auxiliary fields. When inverted, this constraint allows us to obtain the closed non-linear kinetic equation satisfied by the 1-body distribution function. This derivation provides an alternative to previous methods, either based on the direct resolution of the truncated BBGKY hierarc...

  1. A comparison of approaches to estimate the resonance energy

    NARCIS (Netherlands)

    Zielinski, Marcin; Havenith, Remco W. A.; Jenneskens, Leonardus W.; van Lenthe, Joop H.

    2010-01-01

    We discuss Ab Initio approaches to calculate the energy lowering (stabilisation) due to aromaticity. We compare the valence bond method and the block-localised wave function approaches to calculate the resonance energy. We conclude that the valence bond approach employs a Pauling-Wheland resonance e

  2. Functional Bipartite Ranking: a Wavelet-Based Filtering Approach

    OpenAIRE

    Clémençon, Stéphan; Depecker, Marine

    2013-01-01

    It is the main goal of this article to address the bipartite ranking issue from the perspective of functional data analysis (FDA). Given a training set of independent realizations of a (possibly sampled) second-order random function with a (locally) smooth autocorrelation structure and to which a binary label is randomly assigned, the objective is to learn a scoring function s with optimal ROC curve. Based on linear/nonlinear wavelet-based approximations, it is shown how to select compact fin...

  3. COSMETICS AS THEMATIC TO APPROACH ORGANIC FUNCTIONS IN CHEMISTRY TEACHING

    OpenAIRE

    FREITAS, Tasielle Lima; DA COSTA, Maria Aparecida; FREITAS, Fabricia Carla Ribeiro Mendes; OLIVEIRA, Tatiana de Fátima; MORAES, Lilian Marciolina; FIELD’S, Karla Amâncio Pinto; REZENDE, Gláucia Aparecida Andrade; SANTOS, Renato Gomes

    2016-01-01

    The science teaching has become more complex each passing day regarding its approach in an attempt to promote a more effective content learning, what requires from the teachers reflection concerning their education teaching, aiming at the use of different teaching strategies, such as the approach of chemistry contents through their relation to a social context in which they are inserted, as the use of cosmetics. This paper reports on a pedagogical intervention project in the subject of Sup...

  4. Hydrogen bonding and coordination bonding in the electronically excited states of the MOF Cu{sub 2} (L){sub 2} (L=5-(4-pyridyl)tetrazole) CH{sub 2}Cl{sub 2}: A time-dependent density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Sui, Xiao; Mi, Weihong; Ji, Min [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Hao, Ce, E-mail: haoce_dlut@126.com [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Qiu, Jieshan [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)

    2013-10-15

    The solvent-dependent luminescent metal-organic framework (MOF), Cu{sub 2}(L){sub 2}·CH{sub 2}Cl{sub 2} (L=5-(4-pyridyl)tetrazole), in the electronically excited states was studied using time-dependent density functional theory (TDDFT) method. Based on the analysis of the frontier molecular orbitals and electronic configuration, it revealed that the emission is attributed to a ligand-to-metal charge transfer (LMCT). Besides, we investigated the behavior of the hydrogen bonding and coordination bonding in the excited state S{sub 1} of Cu{sub 2}(L){sub 2}·CH{sub 2}Cl{sub 2}. The results indicated that the strength of the hydrogen bonding N5⋯H39-C2 between the dichloromethane molecule and the tetrazole ligand was decreased in the S{sub 1} state, while the coordination bond Cu2-N8 was strengthened in the excited state. Moreover, we further demonstrated that the hydrogen bonding weakening and coordination bonding strengthening should be beneficial to the luminescent process of the MOF. Highlights: ► Solvent-dependent luminescent MOF was studied by TDDFT. ► Emission mechanism was a ligand to metal charge transition (LMCT). ► {sup 1}H NMR and binding energies indicate H-bond weakening in excited states. ► The coordination bonds become stronger in the excited states.

  5. Beta-1 integrin-mediated adhesion may be initiated by multiple incomplete bonds, thus accounting for the functional importance of receptor clustering.

    Science.gov (United States)

    Vitte, Joana; Benoliel, Anne-Marie; Eymeric, Philippe; Bongrand, Pierre; Pierres, Anne

    2004-06-01

    The regulation of cell integrin receptors involves modulation of membrane expression, shift between different affinity states, and topographical redistribution on the cell membrane. Here we attempted to assess quantitatively the functional importance of receptor clustering. We studied beta-1 integrin-mediated attachment of THP-1 cells to fibronectin-coated surfaces under low shear flow. Cells displayed multiple binding events with a half-life of the order of 1 s. The duration of binding events after the first second after arrest was quantitatively accounted for by a model assuming the existence of a short-time intermediate binding state with 3.6 s(-1) dissociation rate and 1.3 s(-1) transition frequency toward a more stable state. Cell binding to surfaces coated with lower fibronectin densities was concluded to be mediated by single molecular interactions, whereas multiple bonds were formed intermediate state. Receptor aggregation was induced by treating cells with neutral antiintegrin antibody and antiimmunoglobulin antibodies. A semiquantitative confocal microscopy study suggested that this treatment increased between 40% and 100% the average number of integrin receptors located in a volume of approximately 0.045 microm(3) surrounding each integrin. This aggregation induced up to 2.7-fold increase of the average number of bonds. Flow cytometric analysis of fluorescent ligand binding showed that THP-1 cells displayed low-affinity beta-1 integrins with a dissociation constant in the micromolar range. It is concluded that the initial step of cell adhesion was mediated by multiple incomplete bonds rather than a single equilibrium-state ligand receptor association. This interpretation accounts for the functional importance of integrin clustering.

  6. 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.

  7. Electronic Coupling Calculations for Bridge-Mediated Charge Transfer Using Constrained Density Functional Theory (CDFT) and Effective Hamiltonian Approaches at the Density Functional Theory (DFT) and Fragment-Orbital Density Functional Tight Binding (FODFTB) Level

    Energy Technology Data Exchange (ETDEWEB)

    Gillet, Natacha; Berstis, Laura; Wu, Xiaojing; Gajdos, Fruzsina; Heck, Alexander; de la Lande, Aurelien; Blumberger, Jochen; Elstner, Marcus

    2016-10-11

    In this article, four methods to calculate charge transfer integrals in the context of bridge-mediated electron transfer are tested. These methods are based on density functional theory (DFT). We consider two perturbative Green's function effective Hamiltonian methods (first, at the DFT level of theory, using localized molecular orbitals; second, applying a tight-binding DFT approach, using fragment orbitals) and two constrained DFT implementations with either plane-wave or local basis sets. To assess the performance of the methods for through-bond (TB)-dominated or through-space (TS)-dominated transfer, different sets of molecules are considered. For through-bond electron transfer (ET), several molecules that were originally synthesized by Paddon-Row and co-workers for the deduction of electronic coupling values from photoemission and electron transmission spectroscopies, are analyzed. The tested methodologies prove to be successful in reproducing experimental data, the exponential distance decay constant and the superbridge effects arising from interference among ET pathways. For through-space ET, dedicated p-stacked systems with heterocyclopentadiene molecules were created and analyzed on the basis of electronic coupling dependence on donor-acceptor distance, structure of the bridge, and ET barrier height. The inexpensive fragment-orbital density functional tight binding (FODFTB) method gives similar results to constrained density functional theory (CDFT) and both reproduce the expected exponential decay of the coupling with donor-acceptor distances and the number of bridging units. These four approaches appear to give reliable results for both TB and TS ET and present a good alternative to expensive ab initio methodologies for large systems involving long-range charge transfers.

  8. The Motivational Function of Private Speech: An Experimental Approach.

    Science.gov (United States)

    de Dios, M. J.; Montero, I.

    Recently, some works have been published exploring the role of private speech as a tool for motivation, reaching beyond the classical research on its regulatory function for cognitive processes such as attention or executive function. In fact, the authors' own previous research has shown that a moderate account of spontaneous private speech of…

  9. The discourse functions of Italian subjects a centering approach

    CERN Document Server

    Eugenio, B D

    1996-01-01

    This paper examines the discourse functions that different types of subjects perform in Italian within the centering framework. I build on my previous work (COLING90) that accounted for the alternation of null and strong pronouns in subject position. I extend my previous analysis in several ways: for example, I refine the notion of {\\sc continue} and discuss the centering functions of full NPs.

  10. Recent approaches in physical modification of protein functionality.

    Science.gov (United States)

    Mirmoghtadaie, Leila; Shojaee Aliabadi, Saeedeh; Hosseini, Seyede Marzieh

    2016-05-15

    Today, there is a growing demand for novel technologies, such as high hydrostatic pressure, irradiation, ultrasound, filtration, supercritical carbon dioxide, plasma technology, and electrical methods, which are not based on chemicals or heat treatment for modifying ingredient functionality and extending product shelf life. Proteins are essential components in many food processes, and provide various functions in food quality and stability. They can create interfacial films that stabilize emulsions and foams as well as interact to make networks that play key roles in gel and edible film production. These properties of protein are referred to as 'protein functionality', because they can be modified by different processing. The common protein modification (chemical, enzymatic and physical) methods have strong effects on the structure and functionality of food proteins. Furthermore, novel technologies can modify protein structure and functional properties that will be reviewed in this study.

  11. Recent approaches in physical modification of protein functionality.

    Science.gov (United States)

    Mirmoghtadaie, Leila; Shojaee Aliabadi, Saeedeh; Hosseini, Seyede Marzieh

    2016-05-15

    Today, there is a growing demand for novel technologies, such as high hydrostatic pressure, irradiation, ultrasound, filtration, supercritical carbon dioxide, plasma technology, and electrical methods, which are not based on chemicals or heat treatment for modifying ingredient functionality and extending product shelf life. Proteins are essential components in many food processes, and provide various functions in food quality and stability. They can create interfacial films that stabilize emulsions and foams as well as interact to make networks that play key roles in gel and edible film production. These properties of protein are referred to as 'protein functionality', because they can be modified by different processing. The common protein modification (chemical, enzymatic and physical) methods have strong effects on the structure and functionality of food proteins. Furthermore, novel technologies can modify protein structure and functional properties that will be reviewed in this study. PMID:26776016

  12. A new approach for the analysis of functionally graded beams

    Directory of Open Access Journals (Sweden)

    M. Mirzababaee

    2006-04-01

    Full Text Available Purpose: It is the intention of the present study to develope a new beam theory for the analysis of functionallygraded compopsite beams to overcome the shortcomings present in the existing beam theories.Design/methodology/approach: Within the displacement field of a first-order shear deformation theory and byusing the Hamilton principle the governing equations of motion are obtained for both the new and the existingbeam theories. The beams are assumed to have isotropic, two-constituent material distribution through thethickness.Findings: It is found that the procedure used is simple and straightforward and similar to the one used in thedevelopment of shear deformation plate and shell theories. It is analytically showed that the new approach yieldsidentical results as those obtained by using the existing first-order shear deformation theory.Research limitations/implications: The new approach can be adopted in developing higher-order sheardeformation and layerwise theories. It is believed that the new approach has advantage with respect to theexisting beam theories especially for developing beam layerwise theories.Practical implications: The new shear deformation beam theory can be used to develop a new beam elementfor analysis of practical composite beam structures.Originality/value: The paper introduces an approach to develop a new theory for modeling composite beams.The resulting equations of motion may be solved analytically or by using finite element method.

  13. A neuroeconomics approach to inferring utility functions in sensorimotor control.

    Directory of Open Access Journals (Sweden)

    Konrad P Körding

    2004-10-01

    Full Text Available Making choices is a fundamental aspect of human life. For over a century experimental economists have characterized the decisions people make based on the concept of a utility function. This function increases with increasing desirability of the outcome, and people are assumed to make decisions so as to maximize utility. When utility depends on several variables, indifference curves arise that represent outcomes with identical utility that are therefore equally desirable. Whereas in economics utility is studied in terms of goods and services, the sensorimotor system may also have utility functions defining the desirability of various outcomes. Here, we investigate the indifference curves when subjects experience forces of varying magnitude and duration. Using a two-alternative forced-choice paradigm, in which subjects chose between different magnitude-duration profiles, we inferred the indifference curves and the utility function. Such a utility function defines, for example, whether subjects prefer to lift a 4-kg weight for 30 s or a 1-kg weight for a minute. The measured utility function depends nonlinearly on the force magnitude and duration and was remarkably conserved across subjects. This suggests that the utility function, a central concept in economics, may be applicable to the study of sensorimotor control.

  14. Metatranscriptomic approach to analyze the functional human gut microbiota.

    Directory of Open Access Journals (Sweden)

    María José Gosalbes

    Full Text Available The human gut is the natural habitat for a large and dynamic bacterial community that has a great relevance for health. Metagenomics is increasing our knowledge of gene content as well as of functional and genetic variability in this microbiome. However, little is known about the active bacteria and their function(s in the gastrointestinal tract. We performed a metatranscriptomic study on ten healthy volunteers to elucidate the active members of the gut microbiome and their functionality under conditions of health. First, the microbial cDNAs obtained from each sample were sequenced using 454 technology. The analysis of 16S transcripts showed the phylogenetic structure of the active microbial community. Lachnospiraceae, Ruminococcaceae, Bacteroidaceae, Prevotellaceae, and Rickenellaceae were the predominant families detected in the active microbiota. The characterization of mRNAs revealed a uniform functional pattern in healthy individuals. The main functional roles of the gut microbiota were carbohydrate metabolism, energy production and synthesis of cellular components. In contrast, housekeeping activities such as amino acid and lipid metabolism were underrepresented in the metatranscriptome. Our results provide new insights into the functionality of the complex gut microbiota in healthy individuals. In this RNA-based survey, we also detected small RNAs, which are important regulatory elements in prokaryotic physiology and pathogenicity.

  15. Enhancement of biodiversity in energy farming: towards a functional approach

    International Nuclear Information System (INIS)

    When biomass is a substantial sustainable energy source, and special energy crops are grown on a large scale, land use and the environment of agriculture will be affected. Of these effects, biodiversity deserves special attention. The enhancement of biodiversity in energy farming via standard setting is the overall purpose of this project. In this study, the potential functionality of biodiversity in energy farming is proposed as a way of operationalising the rather abstract and broad concept of biodiversity. Functions of biodiversity are reviewed, and examples of functions are worked out, based on the current literature of nature in energy farming systems. (author)

  16. The structure, energetics, and nature of the chemical bonding of phenylthiol adsorbed on the Au(111) surface: implications for density-functional calculations of molecular-electronic conduction.

    Science.gov (United States)

    Bilić, Ante; Reimers, Jeffrey R; Hush, Noel S

    2005-03-01

    The adsorption of phenylthiol on the Au(111) surface is modeled using Perdew and Wang density-functional calculations. Both direct molecular physisorption and dissociative chemisorption via S-H bond cleavage are considered as well as dimerization to form disulfides. For the major observed product, the chemisorbed thiol, an extensive potential-energy surface is produced as a function of both the azimuthal orientation of the adsorbate and the linear translation of the adsorbate through the key fcc, hcp, bridge, and top binding sites. Key structures are characterized, the lowest-energy one being a broad minimum of tilted orientation ranging from the bridge structure halfway towards the fcc one. The vertically oriented threefold binding sites, often assumed to dominate molecular electronics measurements, are identified as transition states at low coverage but become favored in dense monolayers. A similar surface is also produced for chemisorption of phenylthiol on Ag(111); this displays significant qualitative differences, consistent with the qualitatively different observed structures for thiol chemisorption on Ag and Au. Full contours of the minimum potential energy as a function of sulfur translation over the crystal face are described, from which the barrier to diffusion is deduced to be 5.8 kcal mol(-1), indicating that the potential-energy surface has low corrugation. The calculated bond lengths, adsorbate charge and spin density, and the density of electronic states all indicate that, at all sulfur locations, the adsorbate can be regarded as a thiyl species that forms a net single covalent bond to the surface of strength 31 kcal mol(-1). No detectable thiolate character is predicted, however, contrary to experimental results for alkyl thiols that indicate up to 20%-30% thiolate involvement. This effect is attributed to the asymptotic-potential error of all modern density functionals that becomes manifest through a 3-4 eV error in the lineup of the adsorbate and

  17. STABILIZATION OF NONLINEAR TIME-VARYING SYSTEMS: A CONTROL LYAPUNOV FUNCTION APPROACH

    Institute of Scientific and Technical Information of China (English)

    Zhongping JIANG; Yuandan LIN; Yuan WANG

    2009-01-01

    This paper presents a control Lyapunov function approach to the global stabilization problem for general nonlinear and time-varying systems. Explicit stabilizing feedback control laws are proposed based on the method of control Lyapunov functions and Sontag's universal formula.

  18. Novel approaches to assessing renal function in cirrhotic liver disease.

    Science.gov (United States)

    Portal, Andrew J; Austin, Mark; Heneghan, Michael A

    2007-09-01

    Renal dysfunction is common in patients with end-stage liver disease. Etiological factors include conditions as diverse as acute tubular necrosis, immunoglobulin A nephropathy and hepatorenal syndrome. Current standard tests of renal function, such as measurement of serum urea and creatinine levels, are inaccurate as the synthesis of these markers is affected by the native liver pathology. This article reviews novel markers of renal function and their potential use in patients with liver disease.

  19. An evolutionary computation approach to examine functional brain plasticity

    OpenAIRE

    Arnab eRoy; Colin eCampbell; Rachel A Bernier; Frank eHillary

    2016-01-01

    One common research goal in systems neurosciences is to understand how the functional relationship between a pair of regions of interest (ROIs) evolves over time. Examining neural connectivity in this way is well-suited for the study of developmental processes, learning, and even in recovery or treatment designs in response to injury. For most fMRI based studies, the strength of the functional relationship between two ROIs is defined as the correlation between the average signal representing ...

  20. An Evolutionary Computation Approach to Examine Functional Brain Plasticity

    OpenAIRE

    Roy, Arnab; Campbell, Colin; Rachel A Bernier; Hillary, Frank G.

    2016-01-01

    One common research goal in systems neurosciences is to understand how the functional relationship between a pair of regions of interest (ROIs) evolves over time. Examining neural connectivity in this way is well-suited for the study of developmental processes, learning, and even in recovery or treatment designs in response to injury. For most fMRI based studies, the strength of the functional relationship between two ROIs is defined as the correlation between the average signal representing ...

  1. A Systemic-Functional Approach to English Ambiguity

    Institute of Scientific and Technical Information of China (English)

    张静

    2014-01-01

    This thesis chooses the theory of rank scale and the theory of meta-function in the framework of Systemic-Functional Grammar (SFG) to study ambiguity. It firstly analyzes ambiguities occurring at the rank of morpheme, word or phrase. Then it studies ambiguities at the rank of clause, from ideational ambiguity to textual ambiguity. This study shows that SFG can give a sys-tematic and comprehensive interpretation of English ambiguity.

  2. Functional integral approach to the kinetic theory of inhomogeneous systems

    Science.gov (United States)

    Fouvry, Jean-Baptiste; Chavanis, Pierre-Henri; Pichon, Christophe

    2016-10-01

    We present a derivation of the kinetic equation describing the secular evolution of spatially inhomogeneous systems with long-range interactions, the so-called inhomogeneous Landau equation, by relying on a functional integral formalism. We start from the BBGKY hierarchy derived from the Liouville equation. At the order 1 / N, where N is the number of particles, the evolution of the system is characterised by its 1-body distribution function and its 2-body correlation function. Introducing associated auxiliary fields, the evolution of these quantities may be rewritten as a traditional functional integral. By functionally integrating over the 2-body autocorrelation, one obtains a new constraint connecting the 1-body DF and the auxiliary fields. When inverted, this constraint allows us to obtain the closed non-linear kinetic equation satisfied by the 1-body distribution function. This derivation provides an alternative to previous methods, either based on the direct resolution of the truncated BBGKY hierarchy or on the Klimontovich equation. It may turn out to be fruitful to derive more accurate kinetic equations, e.g., accounting for collective effects, or higher order correlation terms.

  3. Direction-dependent learning approach for radial basis function networks.

    Science.gov (United States)

    Singla, Puneet; Subbarao, Kamesh; Junkins, John L

    2007-01-01

    Direction-dependent scaling, shaping, and rotation of Gaussian basis functions are introduced for maximal trend sensing with minimal parameter representations for input output approximation. It is shown that shaping and rotation of the radial basis functions helps in reducing the total number of function units required to approximate any given input-output data, while improving accuracy. Several alternate formulations that enforce minimal parameterization of the most general radial basis functions are presented. A novel "directed graph" based algorithm is introduced to facilitate intelligent direction based learning and adaptation of the parameters appearing in the radial basis function network. Further, a parameter estimation algorithm is incorporated to establish starting estimates for the model parameters using multiple windows of the input-output data. The efficacy of direction-dependent shaping and rotation in function approximation is evaluated by modifying the minimal resource allocating network and considering different test examples. The examples are drawn from recent literature to benchmark the new algorithm versus existing methods.

  4. AN IMPROVED MULTIVARIATE LOSS FUNCTION APPROACH TO OPTIMIZATION

    Institute of Scientific and Technical Information of China (English)

    Yizhong MA; Fengyu ZHAO

    2004-01-01

    The basic purpose of a quality loss function is to evaluate a loss to customers in a quantitative manner. Although there are several multivariate loss functions that have been proposed and studied in the literature, it has room for improvement. A good multivariate loss function should represent an appropriate compromise in terms of both process economics and the correlation structure among various responses. More important, it should be easily understood and implemented in practice.According to this criterion, we first introduce a pragmatic dimensionless multivariate loss function proposed by Artiles-Leon, then we improve the multivariate loss function in two respects: one is making it suitable for all three types of quality characteristics; the other is considering correlation structure among the various responses, which makes the improved multivariate loss function more adequate in the real world. On the bases of these, an example from industrial practice is provided to compare our improved method with other methods, and last, some reviews are presented in conclusion.

  5. LAMMPS Framework for Directional Dynamic Bonding

    DEFF Research Database (Denmark)

    2012-01-01

    and bond types. When breaking bonds, all angular and dihedral interactions involving broken bonds are removed. The framework allows chemical reactions to be modeled, and use it to simulate a simplistic, coarse-grained DNA model. The resulting DNA dynamics illustrates the power of the present framework.......We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled...... to limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead...

  6. LETTER TO THE EDITOR: Electronic structure and bonding properties in layered ternary carbide Ti3SiC2

    Science.gov (United States)

    Zhou, Yanchun; Sun, Zhimei

    2000-07-01

    Ab initio calculations based on the density-functional pseudopotential approach have been used to study the electronic structure and chemical bonding in layered machinable Ti3SiC2 ceramic. The calculations reveal that all three types of bonding - metallic, covalent and ionic - contribute to the bonding in Ti3SiC2. The high electric conductivity is attributed to the metallic bonding parallel to the basal plane and the high modulus and high melting point are attributed to the strong Ti-C-Ti-C-Ti covalent bond chains in the structure.

  7. Establishing bonds between vehicle certification data and real-world vehicle fuel consumption – A Vehicle Specific Power approach

    International Nuclear Information System (INIS)

    Highlights: • Innovative methodology to estimate VSP fuel consumption based on public available data. • Model validation with accurate fuel consumption results (absolute deviation from 4.7% to 9.2%). • Best-selling vehicles in Portugal case study was developed for different driving cycles. - Abstract: A method to perform the energy characterization of a vehicle according to the specific power required while driving was developed using public vehicle certification data. Using a portable emission measurement system, fuel consumption was quantified in a second-by-second basis under on-road conditions for 19 vehicles (spark-ignition, compression-ignition and hybrids). This data allowed building generic curves of fuel consumption as a function of the specific power, according to Vehicle Specific Power methodology. Comparing on-road measurements and the model estimates, a R2 higher than 0.9 for conventional and hybrid vehicles was obtained regarding modal fuel consumption. Comparing the fuel consumption measured on the drive cycles performed by each vehicle and the correspondent estimates, an absolute deviation of 9.2% ± 9.2% was found for conventional vehicles and 4.7% ± 1.8% for hybrids vehicles. This methodology was validated and applied to estimate the energy impacts of the best-selling vehicles in Portugal for different driving cycles. This prompt method, that does not require vehicle monitoring, can estimate curves of fuel consumption in g/s, as a function of specific power, which allows quantifying the absolute fuel use for any driving cycle

  8. System Response Analysis and Model Order Reduction, Using Conventional Method, Bond Graph Technique and Genetic Programming

    Directory of Open Access Journals (Sweden)

    Shahid Ali

    2009-04-01

    Full Text Available This research paper basically explores and compares the different modeling and analysis techniques and than it also explores the model order reduction approach and significance. The traditional modeling and simulation techniques for dynamic systems are generally adequate for single-domain systems only, but the Bond Graph technique provides new strategies for reliable solutions of multi-domain system. They are also used for analyzing linear and non linear dynamic production system, artificial intelligence, image processing, robotics and industrial automation. This paper describes a unique technique of generating the Genetic design from the tree structured transfer function obtained from Bond Graph. This research work combines bond graphs for model representation with Genetic programming for exploring different ideas on design space tree structured transfer function result from replacing typical bond graph element with their impedance equivalent specifying impedance lows for Bond Graph multiport. This tree structured form thus obtained from Bond Graph is applied for generating the Genetic Tree. Application studies will identify key issues and importance for advancing this approach towards becoming on effective and efficient design tool for synthesizing design for Electrical system. In the first phase, the system is modeled using Bond Graph technique. Its system response and transfer function with conventional and Bond Graph method is analyzed and then a approach towards model order reduction is observed. The suggested algorithm and other known modern model order reduction techniques are applied to a 11th order high pass filter [1], with different approach. The model order reduction technique developed in this paper has least reduction errors and secondly the final model retains structural information. The system response and the stability analysis of the system transfer function taken by conventional and by Bond Graph method is compared and

  9. Approaches to organizing public relations functions in healthcare.

    Science.gov (United States)

    Guy, Bonnie; Williams, David R; Aldridge, Alicia; Roggenkamp, Susan D

    2007-01-01

    This article provides health care audiences with a framework for understanding different perspectives of the role and functions of public relations in healthcare organizations and the resultant alternatives for organizing and enacting public relations functions. Using an example of a current issue receiving much attention in US healthcare (improving rates of organ donation), the article provides examples of how these different perspectives influence public relations goals and objectives, definitions of 'public', activities undertaken, who undertakes them and where they fit into the organizational hierarchy. PMID:19042525

  10. Approaches to organizing public relations functions in healthcare.

    Science.gov (United States)

    Guy, Bonnie; Williams, David R; Aldridge, Alicia; Roggenkamp, Susan D

    2007-01-01

    This article provides health care audiences with a framework for understanding different perspectives of the role and functions of public relations in healthcare organizations and the resultant alternatives for organizing and enacting public relations functions. Using an example of a current issue receiving much attention in US healthcare (improving rates of organ donation), the article provides examples of how these different perspectives influence public relations goals and objectives, definitions of 'public', activities undertaken, who undertakes them and where they fit into the organizational hierarchy.

  11. Modeling of Heterogeneous Objects: An Approach Based on Implicit Functions

    Directory of Open Access Journals (Sweden)

    Miller Gómez-Mora

    2016-02-01

    Full Text Available Modeling objects, their properties and relations is an important topic in computer science. In this sense, this research contributes to the framework of heterogeneous solid modeling, as well as the popular and intricate study of implicit solid representation. The approach presented here is broad and generic, but this article will focus on bio-CAD models, alluding to the existing extension and implementation in other fields. The overall aim of this work is to demonstrate that solid models of heterogeneous object can be built implicitly. This is shown to have promise in practical applications from biomedical computing to computer animation and engineering. The approach adopted here is based on the observation that current solid models cannot intrinsically represent multiphase geometric information along with the attribute information. This makes necessary to explore new modeling techniques in order to represent real-world objects. The availability of such modeling techniques remains central to the design, analysis, and fabrication of heterogeneous objects

  12. Full CI benchmark calculations on N2, NO, and O2 - A comparison of methods for describing multiple bonds

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1987-01-01

    Full configuration interaction (CI) calculations on the ground states of N2, NO, and O2 using a DZP Gaussian basis are compared with single-reference SDCI and coupled pair approaches (CPF), as well as with CASSCF multireference CI approaches. The CASSCF/MRCI technique is found to describe multiple bonds as well as single bonds. Although the coupled pair functional approach gave chemical accuracy (1 kcal/mol) for bonds involving hydrogen, larger errors occur in the CPF approach for the multiple bonded systems considered here. CI studies on the 1Sigma(g +) state of N2, including all single, double, triple, and quadruple excitations show that triple excitations are very important for the multiple bond case, and accounts for most of the deficiency in the coupled pair functional methods.

  13. Bond Growth under Temperature Gradient.

    Directory of Open Access Journals (Sweden)

    P.K. Satyawali

    1999-12-01

    Full Text Available Grain and bond growth for dry snow are determined by the distribution of temperature andtemperature gradient in the snow matrix. From the standpoint of particle approach and based oncubic packing structure, a bond growth model has been developed for TG metamorphism. The paper.highlights the importance of bond formation and its effect on snow viscosity and finally on the rateof settlement. This is very important for developing a numerical snow pack model if microstructureis considered to be a basic parameter. A few experiments have been carried out to validate bond formation under temperature gradient.

  14. A Functional Approach to Televised Political Spots: Acclaiming, Attacking, Defending.

    Science.gov (United States)

    Benoit, William L.; Pier, P. M.; Blaney, Joseph R.

    1997-01-01

    Articulates a theoretical framework for understanding the fundamental functions of political advertising (acclaiming, attacking, defending) which occur on the twin grounds of policy considerations and character. Applies this theory of political discourse to presidential general election television spots from 1980-1996, finding that Democrats and…

  15. Filling the gap between sequence and function: a bioinformatics approach

    NARCIS (Netherlands)

    Bargsten, J.W.

    2014-01-01

    The research presented in this thesis focuses on deriving function from sequence information, with the emphasis on plant sequence data. Unravelling the impact of genomic elements, in most cases genes, on the phenotype of an organism is a major challenge in biological research and modern plant breedi

  16. Newer Approaches to Identify Potential Untoward Effects in Functional Foods.

    Science.gov (United States)

    Marone, Palma Ann; Birkenbach, Victoria L; Hayes, A Wallace

    2016-01-01

    Globalization has greatly accelerated the numbers and variety of food and beverage products available worldwide. The exchange among greater numbers of countries, manufacturers, and products in the United States and worldwide has necessitated enhanced quality measures for nutritional products for larger populations increasingly reliant on functionality. These functional foods, those that provide benefit beyond basic nutrition, are increasingly being used for their potential to alleviate food insufficiency while enhancing quality and longevity of life. In the United States alone, a steady import increase of greater than 15% per year or 24 million shipments, over 70% products of which are food related, is regulated under the Food and Drug Administration (FDA). This unparalleled growth has resulted in the need for faster, cheaper, and better safety and efficacy screening methods in the form of harmonized guidelines and recommendations for product standardization. In an effort to meet this need, the in vitro toxicology testing market has similarly grown with an anticipatory 15% increase between 2010 and 2015 of US$1.3 to US$2.7 billion. Although traditionally occupying a small fraction of the market behind pharmaceuticals and cosmetic/household products, the scope of functional food testing, including additives/supplements, ingredients, residues, contact/processing, and contaminants, is potentially expansive. Similarly, as functional food testing has progressed, so has the need to identify potential adverse factors that threaten the safety and quality of these products. PMID:26657815

  17. Newton Algorithms for Analytic Rotation: An Implicit Function Approach

    Science.gov (United States)

    Boik, Robert J.

    2008-01-01

    In this paper implicit function-based parameterizations for orthogonal and oblique rotation matrices are proposed. The parameterizations are used to construct Newton algorithms for minimizing differentiable rotation criteria applied to "m" factors and "p" variables. The speed of the new algorithms is compared to that of existing algorithms and to…

  18. Executive function in older adults: a structural equation modeling approach.

    Science.gov (United States)

    Hull, Rachel; Martin, Randi C; Beier, Margaret E; Lane, David; Hamilton, A Cris

    2008-07-01

    Confirmatory factor analysis (CFA) and structural equation modeling (SEM) were used to study the organization of executive functions in older adults. The four primary goals were to examine (a) whether executive functions were supported by one versus multiple underlying factors, (b) which underlying skill(s) predicted performance on complex executive function tasks, (c) whether performance on analogous verbal and nonverbal tasks was supported by separable underlying skills, and (d) how patterns of performance generally compared with those of young adults. A sample of 100 older adults completed 10 tasks, each designed to engage one of three control processes: mental set shifting (Shifting), information updating or monitoring (Updating), and inhibition of prepotent responses (Inhibition). CFA identified robust Shifting and Updating factors, but the Inhibition factor failed to emerge, and there was no evidence for verbal and nonverbal factors. SEM showed that Updating was the best predictor of performance on each of the complex tasks the authors assessed (the Tower of Hanoi and the Wisconsin Card Sort). Results are discussed in terms of insight for theories of cognitive aging and executive function. PMID:18590362

  19. Polymer density functional approach to efficient evaluation of path integrals

    DEFF Research Database (Denmark)

    Brukhno, Andrey; Vorontsov-Velyaminov, Pavel N.; Bohr, Henrik

    2005-01-01

    A polymer density functional theory (P-DFT) has been extended to the case of quantum statistics within the framework of Feynman path integrals. We start with the exact P-DFT formalism for an ideal open chain and adapt its efficient numerical solution to the case of a ring. We show that, similarly...

  20. Bonding in Zintl phase hydrides: density functional calculations for SrAlSiH, SrAl2H2, SrGa2H2 and BaGa2H2

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, Alaska P [ORNL; Singh, David J [ORNL

    2008-01-01

    We investigate the bonding characteristics of SrAlSiH, SrAl{sub 2}H{sub 2}, SrGa{sub 2}H{sub 2}, and BaGa{sub 2}H{sub 2} using density functional calculations. The mixed bonding characteristic of other families of Zintl phases is found, with the formation of covalent sp{sup 2} bonds in the Al/Ga/Al-Si planes of the various compounds. On the other hand the Sr and Ba atoms occur as divalent cations, while the H is anionic. The results indicate that insulating SrSiAlH may be a switchable ferroelectric.

  1. Anomalous scaling and breakdown of conventional density functional theory methods for the description of Mott phenomena and stretched bonds

    Science.gov (United States)

    Ying, Zu-Jian; Brosco, Valentina; Lopez, Giorgia Maria; Varsano, Daniele; Gori-Giorgi, Paola; Lorenzana, José

    2016-08-01

    Density functional theory provides the most widespread framework for the realistic description of the electronic structure of solids, but the description of strongly correlated systems has remained so far elusive. We consider a particular limit of electrons and ions in which a one-band description becomes exact all the way from the weakly correlated metallic regime to the strongly correlated Mott-Hubbard regime. We provide a necessary condition a density functional should fulfill to describe Mott-Hubbard behavior in this one-band limit and show that it is not satisfied by standard and widely used local, semilocal, and hybrid functionals. We illustrate the condition in the case of few-atom systems and provide an analytic approximation to the exact exchange-correlation potential based on a variational wave function which shows explicitly the correct behavior, combining in a neat way lattice and continuum methods.

  2. Hybrid materials of MCM-41 functionalized by lanthanide (Tb3+, Eu3+) complexes of modified meta-methylbenzoic acid: Covalently bonded assembly and photoluminescence

    International Nuclear Information System (INIS)

    Novel organic-inorganic mesoporous hybrid materials were synthesized by linking lanthanide (Tb3+, Eu3+) complexes to the mesoporous MCM-41 through the modified meta-methylbenzoic acid (MMBA-Si) using co-condensation method in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template. The luminescence properties of these resulting materials (denoted as Ln-MMBA-MCM-41, Ln=Tb, Eu) were characterized in detail, and the results reveal that luminescent mesoporous materials have high surface area, uniformity in the ordered mesoporous structure. Moreover, the mesoporous material covalently bonded Tb3+ complex (Tb-MMBA-MCM-41) exhibits the stronger characteristic emission of Tb3+ and longer lifetime than Eu-MMBA-MCM-41 due to the triplet state energy of organic legend MMBA-Si matches with the emissive energy level of Tb3+ very well. - Graphical abstract: Novel organic-inorganic mesoporous luminescent materials were synthesized by linking lanthanide (Tb3+, Eu3+) complexes to covalently bond the functionalized ordered mesoporous MCM-41 with modified meta-methylbenzoic acid (MMBA)-Si by co-condensation of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as template

  3. Ligand-Mediated and Copper-Catalyzed C(sp3)-H Bond Functionalization of Aryl Ketones with Sodium Sulfinates under Mild Conditions

    Science.gov (United States)

    Lan, Xing-Wang; Wang, Nai-Xing; Bai, Cui-Bing; Zhang, Wei; Xing, Yalan; Wen, Jia-Long; Wang, Yan-Jing; Li, Yi-He

    2015-12-01

    A novel and convenient copper (II) bromide and 1,8-diazabicyclo[5.4.1]undec-7-ene (DBU) or 1,10-phenanthroline catalysis protocol for the construction of α-alkyl-β-keto sulfones via C(sp3)-H bond functionalization followed by C(sp3)-S bond formation between aryl ketones and sodium sulfinates at room temperature has been developed. This method is applicable to a wide range of aryl ketones and sodium sulfinates. The electronic effects of aryl ketones and ligands effects of the copper salts are crucial for this transformation. Typically, substituted aryl ketones with electron-withdrawing group do not need any ligand to give a good to excellent yield, while substituted aryl ketones with electron-donating group and electron-rich heteroaromatic ketones offer a good to excellent yield only under the nitrogen-based ligands. The practical value of this transformation highlights the efficient and robust one-pot synthesis of α-alkyl-β-keto sulfones.

  4. FINAL TECHNICAL REPORT for grant DE-FG02-93ER14353 "Carbon-Hydrogen Bond Functionalization Catalyzed by Transition Metal Systems"

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Alan S

    2012-05-21

    Alkanes are our most abundant organic resource but are highly resistant to selective chemical transformations. Alkenes (olefins) by contrast are the single most versatile class of molecules for selective transformations, and are intermediates in virtually every petrochemical process as well as a vast range of commodity and fine chemical processes. Over the course of this project we have developed the most efficient catalysts to date for the selective conversion of alkanes to give olefins, and have applied these catalysts to other dehydrogenation reactions. We have also developed some of the first efficient catalysts for carbonylation of alkanes and arenes to give aldehydes. The development of these catalysts has been accompanied by elucidation of the mechanism of their operation and the factors controlling the kinetics and thermodynamics of C-H bond activation and other individual steps of the catalytic cycles. This fundamental understanding will allow the further improvement of these catalysts, as well as the development of the next generation of catalysts for the functionalization of alkanes and other molecules containing C-H bonds.

  5. Amino-Functionalized Multiwalled Carbon Nanotubes Lead to Successful Ring-Opening Polymerization of Poly(ε-caprolactone): Enhanced Interfacial Bonding and Optimized Mechanical Properties.

    Science.gov (United States)

    Roumeli, Eleftheria; Papageorgiou, Dimitrios G; Tsanaktsis, Vasilios; Terzopoulou, Zoe; Chrissafis, Konstantinos; Avgeropoulos, Apostolos; Bikiaris, Dimitrios N

    2015-06-01

    In this work, the synthesis, structural characteristics, interfacial bonding, and mechanical properties of poly(ε-caprolactone) (PCL) nanocomposites with small amounts (0.5, 1.0, and 2.5 wt %) of amino-functionalized multiwalled carbon nanotubes (f-MWCNTs) prepared by ring-opening polymerization (ROP) are reported. This method allows the creation of a covalent-bonding zone on the surface of nanotubes, which leads to efficient debundling and therefore satisfactory dispersion and effective load transfer in the nanocomposites. The high covalent grafting extent combined with the higher crystallinity provide the basis for a significant enhancement of the mechanical properties, which was detected in the composites with up to 1 wt % f-MWCNTs. Increasing filler concentration encourages intrinsic aggregation forces, which allow only minor grafting efficiency and poorer dispersion and hence inferior mechanical performance. f-MWCNTs also cause a significant improvement on the polymerization reaction of PCL. Indeed, the in situ polymerization kinetics studies reveal a significant decrease in the reaction temperature, by a factor of 30-40 °C, combined with accelerated the reaction kinetics during initiation and propagation and a drastically reduced effective activation energy.

  6. Alternative approach for establishing the Nacelle Transfer Function

    DEFF Research Database (Denmark)

    Krishna, Vinay B.; Ormel, Frank; Hansen, Kurt Schaldemose

    2016-01-01

    -consistency checks have failed to meet the criteria listed in the standard. The root cause analysis against such failure showed that the methodology followed by the standard is less accurate in estimating the free stream wind speed. Suitable changes were made in the process of establishing the nacelle transfer...... will be strongly affected by the wind turbine’s rotor and the nacelle. Suitable correction against such flow distortion is applied through a nacelle transfer function (NTF). The -12-2standard requires a self-consistency check performed on such established NTF using the nacelle power curve. Most of these self...... function and the subsequent self-consistency checks were found to be clearing the criteria set by the standard....

  7. Configuration interaction wave functions: A seniority number approach

    Energy Technology Data Exchange (ETDEWEB)

    Alcoba, Diego R. [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Física de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Torre, Alicia; Lain, Luis, E-mail: qfplapel@lg.ehu.es [Departamento de Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apdo. 644, E-48080 Bilbao (Spain); Massaccesi, Gustavo E. [Departamento de Ciencias Exactas, Ciclo Básico Común, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Oña, Ofelia B. [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Universidad Nacional de La Plata, CCT La Plata, Consejo Nacional de Investigaciones Científicas y Técnicas, Diag. 113 y 64 (S/N), Sucursal 4, CC 16, 1900 La Plata (Argentina)

    2014-06-21

    This work deals with the configuration interaction method when an N-electron Hamiltonian is projected on Slater determinants which are classified according to their seniority number values. We study the spin features of the wave functions and the size of the matrices required to formulate states of any spin symmetry within this treatment. Correlation energies associated with the wave functions arising from the seniority-based configuration interaction procedure are determined for three types of molecular orbital basis: canonical molecular orbitals, natural orbitals, and the orbitals resulting from minimizing the expectation value of the N-electron seniority number operator. The performance of these bases is analyzed by means of numerical results obtained from selected N-electron systems of several spin symmetries. The comparison of the results highlights the efficiency of the molecular orbital basis which minimizes the mean value of the seniority number for a state, yielding energy values closer to those provided by the full configuration interaction procedure.

  8. Approach to combined-function magnets via symplectic slicing

    Science.gov (United States)

    Titze, M.

    2016-05-01

    In this article we describe how to obtain symplectic "slice" maps for combined-function magnets, by using a method of generating functions. A feature of this method is that one can use an unexpanded and unsplit Hamiltonian. From such a slice map we obtain a first-order map which is symplectic at the closed orbit. We also obtain a symplectic kick map. Both results were implemented into the widely used program MAD-X to regain, in particular, the twiss parameters for the sliced model of the Proton Synchrotron at CERN. In addition, we obtain recursion equations for symplectic maps of general time-dependent Hamiltonians, which might be useful even beyond the scope of accelerator physics.

  9. Relativistic Wigner Function Approach to Neutrino Propagation in Matter

    OpenAIRE

    Sirera Tomás, Miguel; Pérez Cañellas, Armando

    1998-01-01

    In this work we study the propagation of massive Dirac neutrinos in matter with flavor mixing, using statistical techniques based on Relativistic Wigner Functions. First, we consider neutrinos in equilibrium within the Hartree approximation, and obtain the corresponding relativistic dispersion relations and effective masses. After this, we analyze the same system out of equilibrium. We verify that, under the appropiate physical conditions, the well known equations for the MSW effect are recov...

  10. Relativistic Wigner function approach to neutrino propagation in matter

    Science.gov (United States)

    Sirera, M.; Pérez, A.

    1999-06-01

    In this work we study the propagation of massive Dirac neutrinos in matter with flavor mixing, using statistical techniques based on relativistic Wigner functions. First, we consider neutrinos in equilibrium within the Hartree approximation, and obtain the corresponding dispersion relations and effective masses. After this, we analyze the same system out of equilibrium. We verify that, under the appropriate physical conditions, the well-known equations for the MSW effect are recovered.

  11. Promoting return of function in multiple sclerosis: An integrated approach

    OpenAIRE

    Gacias, Mar; Casaccia, Patrizia

    2013-01-01

    Multiple sclerosis is a disease characterized by inflammatory demyelination, axonal degeneration and progressive brain atrophy. Most of the currently available disease modifying agents proved to be very effective in managing the relapse rate, however progressive neuronal damage continues to occur and leads to progressive accumulation of irreversible disability. For this reason, any therapeutic strategy aimed at restoration of function must take into account not only immunomodulation, but also...

  12. An information theoretic approach to the functional classification of neurons

    OpenAIRE

    Schneidman, Elad; Bialek, William; Berry II, Michael J.

    2002-01-01

    A population of neurons typically exhibits a broad diversity of responses to sensory inputs. The intuitive notion of functional classification is that cells can be clustered so that most of the diversity is captured in the identity of the clusters rather than by individuals within clusters. We show how this intuition can be made precise using information theory, without any need to introduce a metric on the space of stimuli or responses. Applied to the retinal ganglion cells of the salamander...

  13. I2/O2-Enabled N-S Bond Formation to Access Functionalized 1,2,3-Thiadiazoles.

    Science.gov (United States)

    Fan, Wei; Li, Qun; Li, Yanrong; Sun, Hao; Jiang, Bo; Li, Guigen

    2016-03-18

    A new, metal-free intermolecular formal [3 + 2] heterocyclization between triethylammonium thiolates and aryl hydrazines has been established by using the combination of I2 and O2 as efficient oxidation sources, allowing a concise and low-cost access to new densely functionalized 1,2,3-thiadiazoles with good to excellent yields. The reaction showed a broad scope of substrates of both reactants and attractive characteristics consisting of eco-friendly oxidants, flexible structural modification, broad functional group compatibility, and mild reaction conditions. PMID:26927417

  14. Functional genomic approach to the study of biodiversitywithin Trichoderma

    Institute of Scientific and Technical Information of China (English)

    Monte E; Hermosa M R; González F J; Rey M; Cardoza R E; Gutiérrez S; Delgado Jarana J; Llobell A

    2004-01-01

    @@ Trichoderma is a fungal genus of great and demonstrable biotechnological value, but its genome is poorly surveyed compared with other model microorganisms. Due to their ubiquity and rapid substrate colonization, Trichoderma species have been widely used as biocontrol organisms for agriculture, and their enzyme systems are widely used in industry. Therefore, there is a clear interest to explore beyond the phenotype to exploit the underlying genetic systems using functional genomics tools. The great diversity of species within the Trichoderma genus, the absence of optimized systems for its exploration, and the great variety of genes expressed under a wide range of ambient conditions are the main challenges to consider when starting a comprehensive functional genomics study. An initial project started by three Spanish groups has been extended into the project TRICHOEST, funded by the EU (FP5, QLRT-2001-02032) to target the transcriptome analysis of selected Trichoderma strains with biocontrol potential, in conditions related to antagonism, nutrient stress and plant interactions. Once specific conditions were defined, cDNA libraries were produced and used for EST sequencing. Nine strains from seven Trichoderma species have been considered in this study and an important amount of gene sequence data has been generated, analyzed and used to compare the gene expression in different strains.In parallel to sequencing, genomic expression studies were carried out by means of macro-arrays to identify genes expressed in specific conditions. In silico analysis of DNA sequencing data together with macro-array expression results have lead to a selection based on the potential use of the gene sequences.The selected clone sequences were completed and cloned in appropriate vectors to initiate functional analysis by means of expression studies in homologous and heterologous systems.

  15. Diffusion bonding

    Science.gov (United States)

    Anderson, Robert C.

    1976-06-22

    1. A method for joining beryllium to beryllium by diffusion bonding, comprising the steps of coating at least one surface portion of at least two beryllium pieces with nickel, positioning a coated surface portion in a contiguous relationship with an other surface portion, subjecting the contiguously disposed surface portions to an environment having an atmosphere at a pressure lower than ambient pressure, applying a force upon the beryllium pieces for causing the contiguous surface portions to abut against each other, heating the contiguous surface portions to a maximum temperature less than the melting temperature of the beryllium, substantially uniformly decreasing the applied force while increasing the temperature after attaining a temperature substantially above room temperature, and maintaining a portion of the applied force at a temperature corresponding to about maximum temperature for a duration sufficient to effect the diffusion bond between the contiguous surface portions.

  16. A novel approach to the assessment of vascular endothelial function

    Energy Technology Data Exchange (ETDEWEB)

    Sathasivam, S; Siddiqui, Z; Greenwald, S [Pathology Group, Blizard Institute of Cell and Molecular Science, Barts and The London School of Medicine and Dentistry, Queen Mary University of London (United Kingdom); Phababpha, S; Sengmeuan, P; Detchaporn, P; Kukongviriyapan, U, E-mail: s.e.greenwald@qmul.ac.uk [Department of Physiology, Khon Kaen University, Khon Kaen (Thailand)

    2011-08-17

    Impaired endothelial function (EF) is associated with atherogenesis, and its quantitative assessment has prognostic value. Currently, methods based on assessing flow-mediated dilation (FMD) are technically difficult and expensive. We tested a novel way of assessing EF by measuring the time difference between pulses arriving at the middle fingers of each hand (f-f{Delta}T), whilst FMD is induced in one arm. We compared f-f{Delta}T with standard methods in healthy and diseased subjects. Our findings suggest that the proposed simple and inexpensive technique gives comparable results and has the potential to qualitatively assess EF in the clinical setting, although further work is required.

  17. Relativistic Wigner Function Approach to Neutrino Propagation in Matter

    CERN Document Server

    Sirera, M

    1999-01-01

    In this work we study the propagation of massive Dirac neutrinos in matter with flavor mixing, using statistical techniques based on Relativistic Wigner Functions. First, we consider neutrinos in equilibrium within the Hartree approximation, and obtain the corresponding relativistic dispersion relations and effective masses. After this, we analyze the same system out of equilibrium. We verify that, under the appropiate physical conditions, the well known equations for the MSW effect are recovered. The techniques we used here appear as an alternative to describe neutrino properties and transport equations in a consistent way.

  18. On Spectral Approach to Pascal White Noise Functionals

    Science.gov (United States)

    Barhoumi, Abdessatar; Ouerdiane, Habib; Riahi, Anis

    2011-01-01

    We introduce a one-mode type interacting Fock space {F}NB ( {H}) naturally associated to the negative binomial distribution μr,α. The Fourier transform in generalized joint eigenvectors of a family {Jϕ ; ϕ ∈ ɛ} of Pascal Jacobi fields provides a way to explicit a unitary isomorphism {U}{r,α } between {F}NB ( {H}) and the so-called Pascal white noise space L2(ɛ', Λr,α). Then, we derive a chaotic decomposition property of the quadratic integrable functionals of the Pascal white noise process in terms of an appropriate wick tensor product.

  19. Chemical approaches for mimicking logic functions within fluorescent MPT dyes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The progress of the design, synthesis, fluorescence properties and application of a new family of fluorescent molecular switches towards information processing at the molecular level was reviewed. On the basis of the high fluorescence quantum yields and surroundings-sensitive fluorescent properties of the 5-methoxy-2-(2-pyridyl)-thiazole (2-MPT, 1) and a series of its derivatives as prepared, multiple binary logic and arithmetic functionalities were realized through encoding the controllable fluorescence switching properties with binary digit. Combined with the microfluidic platform, the fabrication of the molecular logic devices was attempted.

  20. Role of Cell-Cell bond for the viability and the function of vascular smooth muscle cells

    Directory of Open Access Journals (Sweden)

    M. Mura

    2010-01-01

    Full Text Available Vascular smooth muscle cell (VSMC viability and homeostasis is regulated by cell-matrix and cell-cell contact: disruption of these interactions are responsible of a switch from a mature to a high proliferative phenotype. VSMCs migration, rate of growth and apoptosis, and the extent of their extracellular matrix (ECM deposition can be also modulated by proatherogenic peptides. Among them, ATII induces the transactivation of IGF I R, which, together with the binding protein IGFBP3, represents a determinant of cell survival, growth and proliferation. Aim of our in vitro study was to verify the role of elective cell-cell bond in moulating the response to ATII. Thus, we evaluated viability, proliferation, IGFIR, IGFBP3 expression and the long term survival and production of ECM in a provisional tissue. A7r5 cell-line was used in adherent cultures or incubated in agarose-coated culture plates to inhibit cell-matrix interactions. Cells, treated or not with ATII 100 nM, were evaluated for apoptosis rate, cell cycle, IGFIR and IGFBP3 protei expression. Fibrin provisional tissue was developed polymerizing a fibrin solution. cantaining A7r5 cells with thrombin. Histological stainings for ECM components were performed on sections of prvisional tissue. An exclusive cell-cell contact resulted to monolayer cell cultures. ATII did not affect the cell survival in both culture conditions, but promoted a 10% decrease in "S" phase and an increases IGFIR expression only in adherent cells. while suspended cell aggregates were resistant to ATII administration; IGFBP3 was reduced both in ATII treated adherent cells and in floating clustered cells, irrespective of the treatmentn. VSMC conditioning in agarose-coated plates before seeding in fibrin provisional matrix reduced, but not abolished, the cell ability to colonize the clot and to produce ECM. This study demonstrates that the elective cell-cell contact induces a quiescent status in cells lacking of cell

  1. VISUALIZATION APPROACH TO STRUCTURE-FUNCTION RELATIONSHIP IN BIOLOGICAL MACROMOLECULES

    Directory of Open Access Journals (Sweden)

    M. Luetić

    2015-08-01

    Full Text Available Introduction: Most of recent research in the field of education strongly recommends the use of visualization in the daily teacher’s practice, especially when it comes to teaching science. Objectives: We investigated the impact of different kinds of visualization on student’s accomplishments, and the relationship between 2D and 3D visualization on the learning outcomes in biochemistry teaching, as well as gender-related differences in 2D vs 3D perception abilities. Materials and Methods: The research study was conducted on a sample of 149 senior secondary school students, devided into three groups: control group (usual teaching approach, and two experimental groups taught using different kinds of visualization: E1 (2D and 3D static visualization tools, and E2 (3D dynamic visualization tools, in addition. Discussion and results: We measured the students’ learning outcomes in biochemistry, as well as the level of satisfaction with different teaching methods. The data were interpreted by performing statistical measures and analyses. In order to validate our hypothesis, we used one-tail and two-tail ANOVA analyses (along with the t-test.Conclusions: There was no statistical significance regarding 2D vs 3D visualization tools in biochemistry teaching. Although there existed some gender-related differences in students’ achievements (in favor of females, it was not established that they were related to the type of visualization (2D or 3D tools applied. However students from the E2 group (additional computer animations were more interested and involved in this kind of teaching. Although the results do not show a statistical significance in favor of 3D visualization, we must conclude that in teaching biochemistry it is certainly a more efficient approach than traditional teacher-oriented lessons. By using this kind of visualization tools in everyday teaching practice, chemistry teachers are given the opportunity to enlighten students with somewhat

  2. [Sensory functions and Alzheimer's disease: a multi-disciplinary approach].

    Science.gov (United States)

    Kenigsberg, Paul-Ariel; Aquino, Jean-Pierre; Berard, Alain; Boucart, Muriel; Bouccara, Didier; Brand, Gérard; Charras, Kevin; Garcia-Larrea, Luis; Gzil, Fabrice; Krolak-Salmon, Pierre; Madjlessi, Arach; Malaquin-Pavan, Évelyne; Penicaud, Luc; Platel, Hervé; Pozzo, Thierry; Reintjens, Christophe; Salmon, Éric; Vergnon, Laurent; Robert, Philippe

    2015-09-01

    Relations between sensory functions and Alzheimer's disease are still under-explored. To understand them better, the Fondation Médéric Alzheimer has brought together a multi-disciplinary expert group. Aristote's five senses must be enhanced by today's knowledge of proprioception, motor cognition and pain perception. When cognition breaks down, the person with dementia perceives the world around her with her sensory experience, yet is unable to integrate all this information to understand the context. The treatment of multiple sensory inputs by the brain is closely linked to cognitive processes. Sensory deficits reduce considerably the autonomy of people with dementia in their daily life and their relations with others, increase their social isolation and the risk of accidents. Professionals involved with neurodegenerative diseases remain poorly aware of sensory deficits, which can bias the results of cognitive tests. However, there are simple tools to detect these deficits, notably for vision, hearing and balance disorders, which can be corrected. Many interventions for cognitive rehabilitation or quality of life improvement are based on sensory functions. The environment of people with dementia must be adapted to become understandable, comfortable, safe and eventually therapeutic. PMID:26395297

  3. Defining the neurocircuitry of borderline personality disorder: functional neuroimaging approaches.

    Science.gov (United States)

    Brendel, Gary R; Stern, Emily; Silbersweig, David A

    2005-01-01

    Functional neuroimaging recently has been used to localize brain dysfunction in borderline personality disorder (BPD). Initial studies have examined baseline activity or emotional reactivity, and our group has investigated what we consider to be a crucial interaction between negative emotion and behavioral (dys)control. This research is beginning to identify abnormal frontolimbic circuitry likely underlying core clinical features of this condition. We review the evidence for dysfunction in specific frontolimbic regions, leading to a mechanistic model of symptom formation in BPD. In addition, we offer an integration of these neuroimaging findings with developmental perspectives on the emergence of borderline psychopathology, focusing on the ways in which early psychosocial experience may interact with developing brain systems. We also consider possible mechanisms of psychotherapeutic change at the neural systems level in BPD. Finally, we propose that future neuroimaging studies of BPD should integrate multiple levels of observation (structural, functional, neurochemical, genetic, and clinical) in a model-driven fashion to further understand the dynamic relationship between biological and psychological factors in the development and treatment of this difficult condition. PMID:16613437

  4. Water as a green solvent for efficient synthesis of isocoumarins through microwave-accelerated and Rh/Cu-catalyzed C-H/O-H bond functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiu; Yan, Yunnan; Wang, Xiaowei; Gong, Binwei; Tang, Xiaobo; Shi, JingJing; Xu, H. Eric; Yi, Wei [Shenyang; (Gannan); (Van Andel); (UST - China); (Chinese Aca. Sci.)

    2014-08-14

    Green chemistry that uses water as a solvent has recently received great attention in organic synthesis. Here we report an efficient synthesis of biologically important isocoumarins through direct cleavage of C–H/O–H bonds by microwave-accelerated and Rh/Cu-catalyzed oxidative annulation of various substituted benzoic acids, where water is used as the only solvent in the reactions. The remarkable features of this “green” methodology include high product yields, wide tolerance of various functional groups as substrates, and excellent region-/site-specificities, thus rendering this methodology a highly versatile and eco-friendly alternative to the existing methods for synthesizing isocoumarins and other biologically important derivatives such as isoquinolones.

  5. Density Functional Studies of the Reaction of Ytterbium Monocation with Fluoromethane: C-F Bond Activation and Electron-Transfer Reactivity

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The potential energy surface and reaction mechanism corresponding to the reaction of ytterbium monocation with fluoromethane,which represents a prototype of the activation of C-F bond in fluorohydrocarbons by bare lanthanide cations,have been investigated for the first time by using density functional theory.A direct fluorine abstraction mechanism was revealed,and the related thermochemistry data were determined.The electron-transfer reactivity of the reaction was analyzed using the two-state model,and a strongly avoided crossing behavior on the transition state region was shown.The present results support the reaction mechanism inferred from early experimental data and the related thermochemistry data can provide a guide for further experimental researches.

  6. Evidence-based concepts and procedures for bonded inlays and onlays. Part I. Historical perspectives and clinical rationale for a biosubstitutive approach.

    Science.gov (United States)

    Dietschi, Didier; Spreafico, Roberto

    2015-01-01

    This first article in the series (Part I) aims to present an updated rationale and treatment approach for indirect adhesive posterior restorations based on the best scientific and long-term clinical evidence available. The proposed treatment concept relies on the basic ideas of (1) the placement of an adhesive base/liner (Dual Bonding [DB] and Cavity Design Optimization [CDO]) and, when needed, (2) a simultaneous relocation of deep cervical margins (Cervical Margin Relocation [CMR]), prior to (3) impression taking to ensure a more conservative preparation and easier-to-follow clinical steps, and the use of (4) a highly filled, light-curing restorative material for the cementation (Controlled Adhesive Cementation [CAC]), together with restoration insertion facilitation, the application of sonic/ultrasonic energy, and/or material heating. The suggested clinical protocol will help the practitioner to eliminate the most frequently experienced difficulties relating to the preparation, isolation, impression taking and cementation of tooth-colored inlays and onlays. This protocol can be applied to both ceramics and composites as no material has been proven to be the most feasible or reliable in all clinical indications regarding its physicochemical and handling characteristics. For the time being, however, we have to regard such indirect restorations as a biosubstitution due to the monolithic nature of the restoration, with still very imperfect replication of the specific natural dentin-enamel assemblage. PMID:25874270

  7. Unsymmetrical Chelation of N-Thioether-Functionalized Bis(diphenylphosphino)amine-Type Ligands and Substituent Effects on the Nuclearity of Iron(II) Complexes: Structures, Magnetism, and Bonding.

    Science.gov (United States)

    Fliedel, Christophe; Rosa, Vitor; Falceto, Andrés; Rosa, Patrick; Alvarez, Santiago; Braunstein, Pierre

    2015-07-01

    Starting from the short-bite ligands N-thioether-functionalized bis(diphenylphosphino)amine-type (Ph2P)2N(CH2)3SMe (1) and (Ph2P)2N(p-C6H4)SMe (2), the Fe(II) complexes [FeCl2(1)]n (3), [FeCl2(2)]2 (4), [Fe(OAc)(1)2]PF6 (5), and [Fe(OAc)(2)2]PF6 (6) were synthesized and characterized by Fourier transform IR, mass spectrometry, elemental analysis, and also by X-ray diffraction for 3, 4, and 6. Complex 3 is a coordination polymer in which 1 acts as a P,P-pseudochelate and a (P,P),S-bridge, whereas 4 has a chlorido-bridged dinuclear structure in which 2 acts only as a P,P-pseudochelate. Since these complexes were obtained under strictly similar synthetic and crystallization conditions, these unexpected differences were ascribed to the different spacer between the nitrogen atom and the −SMe group. In both compounds, one Fe–P bond was found to be unusually long, and a theoretical analysis was performed to unravel the electronic or steric reasons for this difference. Density functional theory calculations were performed for a set of complexes of general formula [FeCl2(SR2){R21PN(R2)P′R23}] (R = H, Me; R1, R2, and R3 = H, Me, Ph), to understand the reasons for the significant deviation of the iron coordination sphere away from tetrahedral as well as from trigonal bipyramidal and the varying degree of unsymmetry of the two Fe–P bonds involving pseudochelating PN(R)P ligands. Electronic factors nicely explain the observed structures, and steric reasons were further ruled out by the structural analysis in the solid-state of the bis-chelated complex 6, which displays usual and equivalent Fe–P bond lengths. Magnetic susceptibility studies were performed to examine how the structural differences between 3 and 4 would affect the interactions between the iron centers, and it was concluded that 3 behaves as an isolated high-spin Fe(II) mononuclear complex, while significant intra- and intermolecular ferromagnetic interactions were evidenced for 4 at low temperatures

  8. An analytic function approach to weak mutually unbiased bases

    Science.gov (United States)

    Olupitan, T.; Lei, C.; Vourdas, A.

    2016-08-01

    Quantum systems with variables in Z(d) are considered, and three different structures are studied. The first is weak mutually unbiased bases, for which the absolute value of the overlap of any two vectors in two different bases is 1 /√{ k } (where k | d) or 0. The second is maximal lines through the origin in the Z(d) × Z(d) phase space. The third is an analytic representation in the complex plane based on Theta functions, and their zeros. It is shown that there is a correspondence (triality) that links strongly these three apparently different structures. For simplicity, the case where d =p1 ×p2, where p1 ,p2 are odd prime numbers different from each other, is considered.

  9. Intelligent platforms for disease assessment: novel approaches in functional echocardiography.

    Science.gov (United States)

    Sengupta, Partho P

    2013-11-01

    Accelerating trends in the dynamic digital era (from 2004 onward) has resulted in the emergence of novel parametric imaging tools that allow easy and accurate extraction of quantitative information from cardiac images. This review principally attempts to heighten the awareness of newer emerging paradigms that may advance acquisition, visualization and interpretation of the large functional data sets obtained during cardiac ultrasound imaging. Incorporation of innovative cognitive software that allow advanced pattern recognition and disease forecasting will likely transform the human-machine interface and interpretation process to achieve a more efficient and effective work environment. Novel technologies for automation and big data analytics that are already active in other fields need to be rapidly adapted to the health care environment with new academic-industry collaborations to enrich and accelerate the delivery of newer decision making tools for enhancing patient care. PMID:24229773

  10. A Derivational Approach to the Operational Semantics of Functional Languages

    DEFF Research Database (Denmark)

    Biernacka, Malgorzata

    substitutions and environment machines. In particular, we show that canonical environment-based abstract machines for evaluation in the lambda calculus, including the Krivine machine for call by name and the CEK machine for call by value, can be systematically derived from a calculus of explicit substitutions......, given a reduction strategy such as normal order or applicative order. Furthermore, we show that the syntactic correspondence applies to languages with context-sensitive reductions, which we illustrate by presenting a number of calculi of explicit substitutions with computational effects (e.g., control...... operators, input/output, stack inspection, laziness and proper tail recursion). Several of the corresponding abstract machines have been independently designed and reported as such in the literature. All the calculi are new. As an application of the syntactic and the functional correspondences, we also...

  11. A statistical mechanical theory of proton transport kinetics in hydrogen-bonded networks based on population correlation functions with applications to acids and bases.

    Science.gov (United States)

    Tuckerman, Mark E; Chandra, Amalendu; Marx, Dominik

    2010-09-28

    Extraction of relaxation times, lifetimes, and rates associated with the transport of topological charge defects in hydrogen-bonded networks from molecular dynamics simulations is a challenge because proton transfer reactions continually change the identity of the defect core. In this paper, we present a statistical mechanical theory that allows these quantities to be computed in an unbiased manner. The theory employs a set of suitably defined indicator or population functions for locating a defect structure and their associated correlation functions. These functions are then used to develop a chemical master equation framework from which the rates and lifetimes can be determined. Furthermore, we develop an integral equation formalism for connecting various types of population correlation functions and derive an iterative solution to the equation, which is given a graphical interpretation. The chemical master equation framework is applied to the problems of both hydronium and hydroxide transport in bulk water. For each case it is shown that the theory establishes direct links between the defect's dominant solvation structures, the kinetics of charge transfer, and the mechanism of structural diffusion. A detailed analysis is presented for aqueous hydroxide, examining both reorientational time scales and relaxation of the rotational anisotropy, which is correlated with recent experimental results for these quantities. Finally, for OH(-)(aq) it is demonstrated that the "dynamical hypercoordination mechanism" is consistent with available experimental data while other mechanistic proposals are shown to fail. As a means of going beyond the linear rate theory valid from short up to intermediate time scales, a fractional kinetic model is introduced in the Appendix in order to describe the nonexponential long-time behavior of time-correlation functions. Within the mathematical framework of fractional calculus the power law decay ∼t(-σ), where σ is a parameter of the

  12. An Approach for Integrating the Prioritization of Functional and Nonfunctional Requirements

    Directory of Open Access Journals (Sweden)

    Mohammad Dabbagh

    2014-01-01

    Full Text Available Due to the budgetary deadlines and time to market constraints, it is essential to prioritize software requirements. The outcome of requirements prioritization is an ordering of requirements which need to be considered first during the software development process. To achieve a high quality software system, both functional and nonfunctional requirements must be taken into consideration during the prioritization process. Although several requirements prioritization methods have been proposed so far, no particular method or approach is presented to consider both functional and nonfunctional requirements during the prioritization stage. In this paper, we propose an approach which aims to integrate the process of prioritizing functional and nonfunctional requirements. The outcome of applying the proposed approach produces two separate prioritized lists of functional and non-functional requirements. The effectiveness of the proposed approach has been evaluated through an empirical experiment aimed at comparing the approach with the two state-of-the-art-based approaches, analytic hierarchy process (AHP and hybrid assessment method (HAM. Results show that our proposed approach outperforms AHP and HAM in terms of actual time-consumption while preserving the quality of the results obtained by our proposed approach at a high level of agreement in comparison with the results produced by the other two approaches.

  13. Functional dyspepsia: A new approach from traditional Persian medicine

    Directory of Open Access Journals (Sweden)

    Mehdi Pasalar

    2016-03-01

    Full Text Available Objective: One of the most common global disorders is related to gastrointestinal system. Functional dyspepsia (FD defined as upper abdominal pain and discomfort in the absence of organic ailments is a prevalent disease without any confirmed medication. The purpose of this study was to find gastric disorders which might be coincidental to FD based on traditional Persian medicine (TPM. Materials and Methods: We searched the main textbooks of TPM including Al-Havi (by Rhazes, Canon of medicine (by Avicenna, ZakhireKhawrazmshahi (by Ismail Jorjani, Moalijat-e Aghili and Makhzan Al-adviya (by Mohammad Hosein AghiliShirazi, and ExirAzam (by Hakim Azam Khan. Also, we searched Pubmed, Scopus, Science Direct, Medline, scientific information database (SID, Iranmedex and Google Scholar from 1980 to 1 August 2014 for dyspepsia, gastrointestinal disease, traditional Persian medicine, and gastric dystemperaments. Results: There is no equivalent term for FD in traditional Persian medicine although similar signs and symptoms are visible in terms like simple cold dystemperament of stomach, indigestion, and digestion debility in TPM sources. Some treatments mentioned in TPM have shown promising results in the current experimental tests. Conclusion: Finding these similarities in complementary and alternative medicine (CAM textbooks may lead to discovering new remedies for this widespread disease.

  14. Approaching human performance the functionality-driven Awiwi robot hand

    CERN Document Server

    Grebenstein, Markus

    2014-01-01

    Humanoid robotics have made remarkable progress since the dawn of robotics. So why don't we have humanoid robot assistants in day-to-day life yet? This book analyzes the keys to building a successful humanoid robot for field robotics, where collisions become an unavoidable part of the game. The author argues that the design goal should be real anthropomorphism, as opposed to mere human-like appearance. He deduces three major characteristics to aim for when designing a humanoid robot, particularly robot hands: _ Robustness against impacts _ Fast dynamics _ Human-like grasping and manipulation performance   Instead of blindly copying human anatomy, this book opts for a holistic design me-tho-do-lo-gy. It analyzes human hands and existing robot hands to elucidate the important functionalities that are the building blocks toward these necessary characteristics.They are the keys to designing an anthropomorphic robot hand, as illustrated in the high performance anthropomorphic Awiwi Hand presented in this book.  ...

  15. Functional and aesthetic approach to design of bird feeders

    Science.gov (United States)

    Kukhta, A.; Kukhta, M.

    2015-10-01

    Anthropogenic objects which load the urban environment negatively affects the human psyche. The alternative is attracting elements of the natural environment into urban environment, of which some of the most frequently identified are birds. Attracting birds in the city is possible by means of feeders and artificial nests, however, both must be harmonious. The aim of this study is to analyze the essential functions of the feeders, and their integration into the environmental design and development of the city. On this basis an original feeder which is convenient for use by birds and attracts people's attention is developed. In this paper we apply comparative analysis of different types of feeders encountered in Tomsk, bird watching, and evaluate usability of different types of feeders from the position of their convenience both for birds and human beings. Historical-cultural analysis for determining features of the architectural and environmental design of Tomsk is carried out, the method allows us to solve engineering problems. In this study the feeder convenient for bird use is designed which blends harmoniously with the architectural design of Tomsk.

  16. Funnel function approach to determine uncertainty: Some advances

    Science.gov (United States)

    Routh, P. S.

    2006-12-01

    Given a finite number of noisy data it is difficult (perhaps impossible) to obtain unique average of the model value in any region of the model (Backus & Gilbert, 1970; Oldenburg, 1983). This difficulty motivated Backus and Gilbert to construct the averaging kernels that is in some sense close to delta function. Averaging kernels describe how the true model is averaged over the entire domain to generate the model value in the region of interest. An unique average value is difficult to obtain theoretically. However we can compute the bounds on the average value and this allows us to obtain a measure of uncertainty. This idea was proposed by Oldenburg (1983). As the region of interest increases the uncertainty decreases associated with the average value giving a funnel like shape. Mathematically this is equivalent to solving minimization and maximization problem of average value (Oldenburg, 1983). In this work I developed a nonlinear interior point method to solve this min-max problem and construct the bounds. The bounds determined in this manner honors all types of available information: (a) geophysical data with errors (b) deterministic or statistical prior information and (c ) complementary information from other data sets at different scales (such as hydrology or other geophysical data) if they are formulated in a joint inversion framework.

  17. Effects of Bonding Types and Functional Groups on CO 2 Capture using Novel Multiphase Systems of Liquid-like Nanoparticle Organic Hybrid Materials

    KAUST Repository

    Lin, Kun-Yi Andrew

    2011-08-01

    Novel liquid-like nanoparticle organic hybrid materials (NOHMs) which possess unique features including negligible vapor pressure and a high degree of tunability were synthesized and their physical and chemical properties as well as CO 2 capture capacities were investigated. NOHMs can be classified based on the synthesis methods involving different bonding types, the existence of linkers, and the addition of task-specific functional groups including amines for CO 2 capture. As a canopy of polymeric chains was grafted onto the nanoparticle cores, the thermal stability of the resulting NOHMs was improved. In order to isolate the entropy effect during CO 2 capture, NOHMs were first prepared using polymers that do not contain functional groups with strong chemical affinity toward CO 2. However, it was found that even ether groups on the polymeric canopy contributed to CO 2 capture in NOHMs via Lewis acid-base interactions, although this effect was insignificant compared to the effect of task-specific functional groups such as amine. In all cases, a higher partial pressure of CO 2 was more favorable for CO 2 capture, while a higher temperature caused an adverse effect. Multicyclic CO 2 capture tests confirmed superior recyclability of NOHMs and NOHMs also showed a higher selectivity toward CO 2 over N 2O, O 2 and N 2. © 2011 American Chemical Society.

  18. Effects of bonding types and functional groups on CO2 capture using novel multiphase systems of liquid-like nanoparticle organic hybrid materials.

    Science.gov (United States)

    Lin, Kun-Yi Andrew; Park, Ah-Hyung Alissa

    2011-08-01

    Novel liquid-like nanoparticle organic hybrid materials (NOHMs) which possess unique features including negligible vapor pressure and a high degree of tunability were synthesized and their physical and chemical properties as well as CO(2) capture capacities were investigated. NOHMs can be classified based on the synthesis methods involving different bonding types, the existence of linkers, and the addition of task-specific functional groups including amines for CO(2) capture. As a canopy of polymeric chains was grafted onto the nanoparticle cores, the thermal stability of the resulting NOHMs was improved. In order to isolate the entropy effect during CO(2) capture, NOHMs were first prepared using polymers that do not contain functional groups with strong chemical affinity toward CO(2). However, it was found that even ether groups on the polymeric canopy contributed to CO(2) capture in NOHMs via Lewis acid-base interactions, although this effect was insignificant compared to the effect of task-specific functional groups such as amine. In all cases, a higher partial pressure of CO(2) was more favorable for CO(2) capture, while a higher temperature caused an adverse effect. Multicyclic CO(2) capture tests confirmed superior recyclability of NOHMs and NOHMs also showed a higher selectivity toward CO(2) over N(2)O, O(2) and N(2).

  19. Family therapy for adolescents with functional somatic symptoms: A systemic narrative approach on a biopsychosocial foundation

    DEFF Research Database (Denmark)

    Dehlholm-Lambertsen, Birgitte; Hulgaard, Ditte Roth

    evidence on the effect of psychological treatment. At the department of Child and Adolescent Psychiatry, University Hospital of Southern Denmark, a team of experienced therapists has developed an approach for the treatment of adolescents with FSS. This approach includes a formalized and well...... and Adolescent Psychiatry, University Hospital of Southern Denmark. • Discussion of different approaches to family therapy for adolescents with functional somatic symptoms • Discussion of challenges and advantages of a systemic narrative approach to families of adolescents with functional somatic symptoms....

  20. Photoinduced hydrogen-bonding dynamics.

    Science.gov (United States)

    Chu, Tian-Shu; Xu, Jinmei

    2016-09-01

    Hydrogen bonding dynamics has received extensive research attention in recent years due to the significant advances in femtolaser spectroscopy experiments and quantum chemistry calculations. Usually, photoexcitation would cause changes in the hydrogen bonding formed through the interaction between hydrogen donor and acceptor molecules on their ground electronic states, and such transient strengthening or weakening of hydrogen bonding could be crucial for the photophysical transformations and the subsequent photochemical reactions that occurred on a time scale from tens of femtosecond to a few nanoseconds. In this article, we review the combined experimental and theoretical studies focusing on the ultrafast electronic and vibrational hydrogen bonding dynamics. Through these studies, new mechanisms and proposals and common rules have been put forward to advance our understanding of the hydrogen bondings dynamics in a variety of important photoinduced phenomena like photosynthesis, dual fluorescence emission, rotational reorientation, excited-state proton transfer and charge transfer processes, chemosensor fluorescence sensing, rearrangements of the hydrogen-bond network including forming and breaking hydrogen bond in water. Graphical Abstract We review the recent advances on exploring the photoinduced hydrogen bonding dynamics in solutions through a joint approach of laser spectroscopy and theoretical calculation. The reviewed studies have put forward a new mechanism, new proposal, and new rule for a variety of photoinduced phenomena such as photosynthesis, dual fluorescence emission, rotational reorientation, excited-state proton transfer and charge transfer, chemosensor fluorescence sensing, and rearrangements of the hydrogen-bond network in water. PMID:27491849

  1. A3-Coupling catalyzed by robust Au nanoparticles covalently bonded to HS-functionalized cellulose nanocrystalline films

    Directory of Open Access Journals (Sweden)

    Jian-Lin Huang

    2013-07-01

    Full Text Available We decorated HS-functionalized cellulose nanocrystallite (CNC films with monodisperse Au nanoparticles (AuNPs to form a novel nanocomposite catalyst AuNPs@HS-CNC. The uniform, fine AuNPs were made by the reduction of HAuCl4 solution with thiol (HS- group-functionalized CNC films. The AuNPs@HS-CNC nanocomposites were examined by X-ray photoelectron spectroscopy (XPS, TEM, ATR-IR and solid-state NMR. Characterizations suggested that the size of the AuNPs was about 2–3 nm and they were evenly distributed onto the surface of CNC films. Furthermore, the unique nanocomposite Au@HS-CNC catalyst displayed high catalytic efficiency in promoting three-component coupling of an aldehyde, an alkyne, and an amine (A3-coupling either in water or without solvent. Most importantly, the catalyst could be used repetitively more than 11 times without significant deactivation. Our strategy also promotes the use of naturally renewable cellulose to prepare reusable nanocomposite catalysts for organic synthesis.

  2. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    Directory of Open Access Journals (Sweden)

    Conrad Schittko

    Full Text Available A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion.

  3. Using a multi-trait approach to manipulate plant functional diversity in a biodiversity-ecosystem function experiment.

    Science.gov (United States)

    Schittko, Conrad; Hawa, Mahmoud; Wurst, Susanne

    2014-01-01

    A frequent pattern emerging from biodiversity-ecosystem function studies is that functional group richness enhances ecosystem functions such as primary productivity. However, the manipulation of functional group richness goes along with major disadvantages like the transformation of functional trait data into categories or the exclusion of functional differences between organisms in the same group. In a mesocosm study we manipulated plant functional diversity based on the multi-trait Functional Diversity (FD)-approach of Petchey and Gaston by using database data of seven functional traits and information on the origin of the species in terms of being native or exotic. Along a gradient ranging from low to high FD we planted 40 randomly selected eight-species mixtures under controlled conditions. We found a significant positive linear correlation of FD with aboveground productivity and a negative correlation with invasibility of the plant communities. Based on community-weighted mean calculations for each functional trait, we figured out that the traits N-fixation and species origin, i.e. being native or exotic, played the most important role for community productivity. Our results suggest that the identification of the impact of functional trait diversity and the relative contributions of relevant traits is essential for a mechanistic understanding of the role of biodiversity for ecosystem functions such as aboveground biomass production and resistance against invasion.

  4. Modified bonded bridge space maintainer.

    Science.gov (United States)

    Liegeois, F; Limme, M

    1999-01-01

    The premature loss of primary teeth can create the need for space maintenance and restoration of function. This article presents a fixed bonded space maintainer, which allows space to be maintained with economy of dental tissues.

  5. A Multi-Atlas Labeling Approach for Identifying Subject-Specific Functional Regions of Interest.

    Science.gov (United States)

    Huang, Lijie; Zhou, Guangfu; Liu, Zhaoguo; Dang, Xiaobin; Yang, Zetian; Kong, Xiang-Zhen; Wang, Xu; Song, Yiying; Zhen, Zonglei; Liu, Jia

    2016-01-01

    The functional region of interest (fROI) approach has increasingly become a favored methodology in functional magnetic resonance imaging (fMRI) because it can circumvent inter-subject anatomical and functional variability, and thus increase the sensitivity and functional resolution of fMRI analyses. The standard fROI method requires human experts to meticulously examine and identify subject-specific fROIs within activation clusters. This process is time-consuming and heavily dependent on experts' knowledge. Several algorithmic approaches have been proposed for identifying subject-specific fROIs; however, these approaches cannot easily incorporate prior knowledge of inter-subject variability. In the present study, we improved the multi-atlas labeling approach for defining subject-specific fROIs. In particular, we used a classifier-based atlas-encoding scheme and an atlas selection procedure to account for the large spatial variability across subjects. Using a functional atlas database for face recognition, we showed that with these two features, our approach efficiently circumvented inter-subject anatomical and functional variability and thus improved labeling accuracy. Moreover, in comparison with a single-atlas approach, our multi-atlas labeling approach showed better performance in identifying subject-specific fROIs.

  6. A Computational Approach to Essential and Nonessential Objective Functions in Linear Multicriteria Optimization

    CERN Document Server

    Malinowska, Agnieszka B

    2007-01-01

    The question of obtaining well-defined criteria for multiple criteria decision making problems is well-known. One of the approaches dealing with this question is the concept of nonessential objective function. A certain objective function is called nonessential if the set of efficient solutions is the same both with or without that objective function. In this paper we put together two methods for determining nonessential objective functions. A computational implementation is done using a computer algebra system.

  7. From Common Sense Concepts to Scientifically Conditioned Concepts of Chemical Bonding: An Historical and Textbook Approach Designed to Address Learning and Teaching Issues at the Secondary School Level

    Science.gov (United States)

    Croft, Michael; de Berg, Kevin

    2014-09-01

    This paper selects six key alternative conceptions identified in the literature on student understandings of chemical bonding and illustrates how a historical analysis and a textbook analysis can inform these conceptions and lead to recommendations for improving the teaching and learning of chemical bonding at the secondary school level. The historical analysis and the textbook analysis focus on the concepts of charge, octet, electron pair, ionic, covalent and metallic bonding. Finally, a table of recommendations is made for teacher and student in the light of four fundamental questions and the six alternative conceptions to enhance the quality of the curriculum resources available and the level of student engagement.

  8. On the accuracy of density-functional theory exchange-correlation functionals for H bonds in small water clusters. II. The water hexamer and van der Waals interactions

    NARCIS (Netherlands)

    Santra, Biswajit; Michaelides, Angelos; Fuchs, Martin; Tkatchenko, Alexandre; Filippi, Claudia; Scheffler, Matthias

    2008-01-01

    Second order Møller–Plesset perturbation theory at the complete basis set limit and diffusion quantum Monte Carlo are used to examine several low energy isomers of the water hexamer. Both approaches predict the so-called prism to be the lowest energy isomer, followed by cage, book, and cyclic isomer

  9. Composite-hydroxide-mediated approach an effective synthesis route for BaTiO3 functional nanomaterials

    Science.gov (United States)

    Khan, Taj Muhammad; Zakria, M.; Shakoor, Rana. I.; Hussain, Shabbir

    2016-04-01

    This paper describes synthesis of the functional BaTiO3 (BT) nanostructures by composite-hydroxide-mediated (CHM) approach. The effect of processing temperature on the nucleation and the optical, structural properties is investigated. The nanostructures prepared at various temperatures (180, 220 and 250 °C) are thermally stable and nucleate in different morphologies, which shows a temperature-dependent mechanism of the CHM approach. The nanostructures are cubic in nature with an average particle size in the range of 97-250 nm. The local crystal structure investigated by Raman spectroscopy reveals a certain degree of tetragonality on atomic scale in the local phase structure. The micrographs of scanning electron microscopy (SEM) indicate formation of the nanocuboids at 180 and 220 °C with larger particle size. At 250 °C, the product shows ball-like spherical morphology. Energy-dispersive X-ray (EDX) confirms the existence of Ba, Ti and O elements in the product, which indicates a chemically pure product. Further signature on the formation, purity and chemical bonding is obtained from FT-IR spectroscopy. Based on these experimental results, size, morphology manipulation and possible growth mechanisms are proposed with CHM at low temperature and without surfactant.

  10. The dynamic dielectric at a brain functional site and an EM wave approach to functional brain imaging.

    Science.gov (United States)

    Li, X P; Xia, Q; Qu, D; Wu, T C; Yang, D G; Hao, W D; Jiang, X; Li, X M

    2014-11-04

    Functional brain imaging has tremendous applications. The existing methods for functional brain imaging include functional Magnetic Resonant Imaging (fMRI), scalp electroencephalography (EEG), implanted EEG, magnetoencephalography (MEG) and Positron Emission Tomography (PET), which have been widely and successfully applied to various brain imaging studies. To develop a new method for functional brain imaging, here we show that the dielectric at a brain functional site has a dynamic nature, varying with local neuronal activation as the permittivity of the dielectric varies with the ion concentration of the extracellular fluid surrounding neurons in activation. Therefore, the neuronal activation can be sensed by a radiofrequency (RF) electromagnetic (EM) wave propagating through the site as the phase change of the EM wave varies with the permittivity. Such a dynamic nature of the dielectric at a brain functional site provides the basis for an RF EM wave approach to detecting and imaging neuronal activation at brain functional sites, leading to an RF EM wave approach to functional brain imaging.

  11. Bond graph modeling of centrifugal compression systems

    OpenAIRE

    Uddin, Nur; Gravdahl, Jan Tommy

    2015-01-01

    A novel approach to model unsteady fluid dynamics in a compressor network by using a bond graph is presented. The model is intended in particular for compressor control system development. First, we develop a bond graph model of a single compression system. Bond graph modeling offers a different perspective to previous work by modeling the compression system based on energy flow instead of fluid dynamics. Analyzing the bond graph model explains the energy flow during compressor surge. Two pri...

  12. Transcendental Functions and Initial Value Problems: A Different Approach to Calculus II

    Science.gov (United States)

    Cha, Byungchul

    2007-01-01

    We present an approach of defining certain transcendental functions as solutions to initial value problems or systems of such problems. This material is suitable for use in a second-semester one-variable calculus course.

  13. Confinement effects on the steel-concrete bond strength and pull-out failure

    International Nuclear Information System (INIS)

    In this contribution, an experimental campaign based on unconfined and actively confined pull-out tests is presented to investigate the bond stress-slip behavior. This campaign aims at underlining passive (concrete cover) and active (external pressure) confinement effects on the maximal bond stress. Experimental results are associated to a numerical approach in order to predict the evolution of the bond strength. Equations are finally proposed that distinguish splitting failure (function of the concrete tensile properties) and pull-out failure (function of the compressive concrete properties). (authors)

  14. A crystal chemistry approach for high-power ytterbium doped solid-state lasers: diffusion-bonded crystals and new crystalline hosts

    International Nuclear Information System (INIS)

    This work deals with ytterbium based crystals for high-power laser applications. In particular, we focus our interest in reducing crystal heating and its consequences during laser operation following two different ways. First, we review the specific properties of ytterbium doped solid-state lasers in order to define a figure-of-merit which gives the evaluation of laser performances, thermo-mechanical and thermo-optical properties. Bearing in mind this analysis, we propose a set of theoretical tools, based on the crystallographic structure of the crystal and its chemical composition, to predict thermo-mechanical and optical potentials. This approach, used for the seek of new Yb3+-doped materials for high-power laser applications, shows that simple oxides containing rare-earths are favorable. Therefore, the spectroscopic properties of six new materials Yb3+:GdVO4, Yb3+:GdAlO3, Yb3+:Gd2O3, Yb3+:Sc2SiO5, Yb3+:CaSc2O4 and Yb3+:SrSc2O4 are described. The second aspect developed in this work deals with thermal properties enhancement of already well characterized laser materials. Two different ways are explored: a) elaboration by diffusion bonding of end-caps lasers with undoped crystals (composite crystals). Thus, different composites were obtained and a fairly lowering of thermal lensing effect was observed during laser operation. b) strengthening of crystalline structures by ionic substitution of one of its constituents. We demonstrate how crystal growth ability can be improved by a cationic substitution in the case of Yb3+:BOYS, a largely-tunable laser material which is of great interest for femtosecond pulses generation. (author)

  15. The properties of mesoporous silica nanoparticles functionalized with different PEG-chain length via the disulfide bond linker and drug release in glutathione medium.

    Science.gov (United States)

    Xie, Zhifei; Gong, Huameng; Liu, Mingxing; Zhu, Hongda; Sun, Honghao

    2016-01-01

    In this paper, a novel drug-loaded material (MSNs-SS-PEG) was obtained by grafting the thiol-linked methoxy polyethylene glycol (MeOPEG-SH) onto the thiol-functionalized mesoporous silica nanoparticles (MSNs-SH) via the disulfide bond linker. In our designed experiment, three different chain lengths of PEG (PEG(1000), PEG(5000), and PEG(1000)-PEG(5000)) were used. The silica materials were characterized by Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, field emission scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption measurements, and X-ray diffraction. The morphology of the MSNs-SS-PEG was spherical with an average diameter of about 150 nm. Due to the covalent modification of hydrophilic MeOPEG, the MSNs-SS-PEG was coated by a thin polymer shell, showing stable and inerratic MCM-41 type mesoporous structure as well as high specific surface areas and large pore volumes. Moreover, the releases of doxorubicin hydrochloride (DOX) from these materials at 10 mM of glutathione were investigated. The PEG functionalization could effectively cap drugs in the mesoporous channels. The release of DOX from the MSNs-SS-PEG(n) revealed redox-responsive characteristic. The obtained results showed that the MSNs-SS-PEG might be promising drug delivery carrier materials, which could play an important role in the development of drug delivery. PMID:26540096

  16. Rhodium-Catalyzed C-C Bond Formation via Heteroatom-Directed C-H Bond Activation

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Denise; Bergman, Robert; Ellman, Jonathan

    2010-05-13

    Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach

  17. Points of convergence between functional and formal approaches to syntactic analysis

    DEFF Research Database (Denmark)

    Bjerre, Tavs; Engels, Eva; Jørgensen, Henrik;

    2008-01-01

    respectively: The functional approach is represented by Paul Diderichsen's (1936, 1941, 1946, 1964) sætningsskema, ‘sentence model', and the formal approach is represented by analysis whose main features are common to the principles and parameters framework (Chomsky 1986) and the minimalist programme (Chomsky...

  18. A robust outlier approach to prevent type I error inflation in Differential Item Functioning

    NARCIS (Netherlands)

    D. Magis; P. de Boeck

    2012-01-01

    The identification of differential item functioning (DIF) is often performed by means of statistical approaches that consider the raw scores as proxies for the ability trait level. One of the most popular approaches, the Mantel-Haenszel (MH) method, belongs to this category. However, replacing the a

  19. Functionally Approached Body (FAB) Strategies for Young Children Who Have Behavioral and Sensory Processing Challenges

    Science.gov (United States)

    Pagano, John

    2005-01-01

    Functionally Approached Body (FAB) Strategies offer a clinical approach to help parents of young children with behavioral and sensory processing strategies. This article introduces the FAB Strategies, clinical strategies developed by the author for understanding and addressing young children's behavioral and sensory processing challenges. The FAB…

  20. A distance function approach to school-leavers’ efficiency in the school-to-work transition

    OpenAIRE

    B. DEFLOOR; L. VAN OOTEGEM; E. VERHOFSTADT

    2010-01-01

    Two conventional approaches to study the school-to-work transition are the duration period to the first job and the satisfaction in (or for some specific characteristics of) the first job. This paper compares these two approaches with an analysis of the efficiency of school-leavers? first job achievement. The transformation of resources, when leaving school, into achieved first job characteristics is analysed using a multi-input multi-output stochastic distance function approach. This allows ...

  1. Quantitative bond energetics in atomic-scale junctions with significant van der Waals character

    Science.gov (United States)

    Venkataraman, Latha; Aradhya, Sriharsha; Hybertsen, Mark

    2015-03-01

    A direct measurement of the potential energy surface that characterizes individual chemical bonds in complex materials has fundamental significance for many disciplines. Here, we demonstrate that the energy profile for metallic single-atom contacts and single-molecule junctions can be mapped by fitting ambient atomic force microscope measurements carried out in the near-equilibrium regime to a physical, but simple, functional form. In particular we are able to extract bond energies for metal-molecule link bonds in cases where the interaction has significant contribution from nonspecific interactions attributed to van der Waals (vdW) interactions at short length scale in addition to specific donor-acceptor bonds. Our approach significantly expands the quantitative information extracted from these measurements, allowing direct comparisons to density functional theory (DFT) calculations instead of relying on trends in bond rupture forces alone. Currently at Cornell University.

  2. Synthesis, molecular structure, spectral analysis, natural bond order and intramolecular interactions of 2-acetylpyridine thiosemicarbazone: A combined DFT and AIM approach

    Science.gov (United States)

    Singh, Ravindra Kumar; Singh, Ashok Kumar

    2015-08-01

    2-Acetylpyridine thiosemicarbazone was synthesized and characterized by elemental analysis, 1H, 13C NMR, IR, UV and ESI-MS mass spectrometry. Quantum chemical calculations have been performed at DFT level of theory using B3LYP functional and 6-31G (d, p) as basis set. Potential energy distribution (PED) for the normal modes of vibrations was done using Gar2ped program. The time dependent density functional theory (TD-DFT) was used to assign the various electronic transitions within molecule in gas as well as solvent phase. Non linear optical (NLO) behavior of title compound was investigated by the computed value of first hyperpolarizability (β0). Stability of molecule as a result of hyperconjugative interactions and electron delocalization was analyzed using NBO analysis. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Intramolecular interactions were analyzed by AIM approach. The chemical reactivity descriptors were calculated to study the reactive sites within molecule.

  3. Measuring Social Returns to Higher Education Investments in Hong Kong: Production Function Approach.

    Science.gov (United States)

    Voon, Jan P.

    2001-01-01

    Uses a growth model involving an aggregate production function to measure social benefits from human capital improvements due to investments in Hong Kong higher education. Returns calculated using the production-function approach are significantly higher than those derived from the wage-increment method. Returns declined during the past 10 years.…

  4. A Two Layer Approach to the Computability and Complexity of Real Functions

    DEFF Research Database (Denmark)

    Lambov, Branimir Zdravkov

    2003-01-01

    We present a new model for computability and complexity of real functions together with an implementation that it based on it. The model uses a two-layer approach in which low-type basic objects perform the computation of a real function, but, whenever needed, can be complemented with higher type...

  5. A Functional-Notional Approach for English for Specific Purposes (ESP) Programs.

    Science.gov (United States)

    Kim, Young-Min

    English for Specific Purposes (ESP) programs, characterized by the special needs of the language learners, are described and a review of the literature on a functional-notional approach to the syllabus design of ESP programs is presented. It is suggested that effective ESP programs should teach the language skills necessary to function and perform…

  6. Controlled growth of silica-titania hybrid functional nanoparticles through a multistep microfluidic approach.

    Science.gov (United States)

    Shiba, K; Sugiyama, T; Takei, T; Yoshikawa, G

    2015-11-11

    Silica/titania-based functional nanoparticles were prepared through controlled nucleation of titania and subsequent encapsulation by silica through a multistep microfluidic approach, which was successfully applied to obtaining aminopropyl-functionalized silica/titania nanoparticles for a highly sensitive humidity sensor.

  7. Thread bonds in molecules

    CERN Document Server

    Ivlev, B

    2015-01-01

    Unusual chemical bonds are proposed. Each bond is almost covalent but is characterized by the thread of a small radius $\\sim 0.6\\times 10^{-11}$cm, between two nuclei in a molecule. The main electron density is concentrated outside the thread as in a covalent bond. The thread is formed by the electron wave function which has a tendency to be singular on it. The singularity along the thread is cut off by electron "vibrations" due to the interaction with zero point electromagnetic oscillations. The electron energy has its typical value of (1-10)eV. Due to the small tread radius the uncertainty of the electron momentum inside the thread is large resulting in a large electron kinetic energy $\\sim 1 MeV$. This energy is compensated by formation of a potential well due to the reduction of the energy of electromagnetic zero point oscillations. This is similar to formation of a negative van der Waals potential. Thread bonds are stable and cannot be created or destructed in chemical or optical processes.

  8. The chemisorptive bond basic concepts

    CERN Document Server

    Clark, Alfred

    1974-01-01

    The Chemisorptive Bond: Basic Concepts describes the basic concepts of the chemisorptive bond on solid surfaces from the simple analogies with ordinary chemical bonds to the quantum-mechanical approaches.This book is composed of 10 chapters and begins with discussions of simple formulas for correlating measurable quantities in chemisorptions and catalysis. The succeeding chapters deal with theories based on quantum-mechanical principles that describe the mutual interactions of atoms of the solid and foreign atoms on the surface. The remaining chapters consider the possible arrangements

  9. A novel pattern mining approach for identifying cognitive activity in EEG based functional brain networks.

    Science.gov (United States)

    Thilaga, M; Vijayalakshmi, R; Nadarajan, R; Nandagopal, D

    2016-06-01

    The complex nature of neuronal interactions of the human brain has posed many challenges to the research community. To explore the underlying mechanisms of neuronal activity of cohesive brain regions during different cognitive activities, many innovative mathematical and computational models are required. This paper presents a novel Common Functional Pattern Mining approach to demonstrate the similar patterns of interactions due to common behavior of certain brain regions. The electrode sites of EEG-based functional brain network are modeled as a set of transactions and node-based complex network measures as itemsets. These itemsets are transformed into a graph data structure called Functional Pattern Graph. By mining this Functional Pattern Graph, the common functional patterns due to specific brain functioning can be identified. The empirical analyses show the efficiency of the proposed approach in identifying the extent to which the electrode sites (transactions) are similar during various cognitive load states.

  10. Hexacoordinate bonding and aromaticity in silicon phthalocyanine.

    Science.gov (United States)

    Yang, Yang

    2010-12-23

    Si-E bondings in hexacoordinate silicon phthalocyanine were analyzed using bond order (BO), energy partition, atoms in molecules (AIM), electron localization function (ELF), and localized orbital locator (LOL). Bond models were proposed to explain differences between hexacoordinate and tetracoordinate Si-E bondings. Aromaticity of silicon phthalocyanine was investigated using nucleus-independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), conceptual density functional theory (DFT), ring critical point (RCP) descriptors, and delocalization index (DI). Structure, energy, bonding, and aromaticity of tetracoordinate silicon phthalocyanine were studied and compared with hexacoordinate one. PMID:21105726

  11. Biodiversity and multifunctionality in a microbial community: a novel theoretical approach to quantify functional redundancy

    OpenAIRE

    Miki, Takeshi; Yokokawa, Taichi; Matsui, Kazuaki

    2014-01-01

    Ecosystems have a limited buffering capacity of multiple ecosystem functions against biodiversity loss (i.e. low multifunctional redundancy). We developed a novel theoretical approach to evaluate multifunctional redundancy in a microbial community using the microbial genome database (MBGD) for comparative analysis. In order to fully implement functional information, we defined orthologue richness in a community, each of which is a functionally conservative evolutionary unit in genomes, as an ...

  12. Heterocyclization Approach for Electrooxidative Coupling of Functional Primary Alkylamines with Aromatics.

    Science.gov (United States)

    Morofuji, Tatsuya; Shimizu, Akihiro; Yoshida, Jun-ichi

    2015-08-12

    A new approach for electrooxidative coupling of aromatic compounds and primary alkylamines bearing a functional group such as a hydroxyl group and an amino group was developed. The key to the success of the transformation is heterocyclization of functional primary alkylamines. Treatment of primary alkylamines bearing a functional group with nitriles or their equivalents gives the corresponding heterocycles. The electrochemical oxidation of aromatic substrates in the presence of the heterocycles followed by chemical reaction under nonoxidative conditions gave the desired coupling products.

  13. A functional approach to movement analysis and error identification in sports and physical education

    Directory of Open Access Journals (Sweden)

    Ernst-Joachim eHossner

    2015-09-01

    Full Text Available In a hypothesis-and-theory paper, a functional approach to movement analysis in sports is introduced. In this approach, contrary to classical concepts, it is not anymore the ideal movement of elite athletes that is taken as a template for the movements produced by learners. Instead, movements are understood as the means to solve given tasks that in turn, are defined by to-be-achieved task goals. A functional analysis comprises the steps of (1 recognising constraints that define the functional structure, (2 identifying sub-actions that subserve the achievement of structure-dependent goals, (3 explicating modalities as specifics of the movement execution, and (4 assigning functions to actions, sub-actions and modalities. Regarding motor-control theory, a functional approach can be linked to a dynamical-system framework of behavioural shaping, to cognitive models of modular effect-related motor control as well as to explicit concepts of goal setting and goal achievement. Finally, it is shown that a functional approach is of particular help for sports practice in the context of structuring part practice, recognising functionally equivalent task solutions, finding innovative technique alternatives, distinguishing errors from style, and identifying root causes of movement errors.

  14. A functional approach to movement analysis and error identification in sports and physical education.

    Science.gov (United States)

    Hossner, Ernst-Joachim; Schiebl, Frank; Göhner, Ulrich

    2015-01-01

    In a hypothesis-and-theory paper, a functional approach to movement analysis in sports is introduced. In this approach, contrary to classical concepts, it is not anymore the "ideal" movement of elite athletes that is taken as a template for the movements produced by learners. Instead, movements are understood as the means to solve given tasks that in turn, are defined by to-be-achieved task goals. A functional analysis comprises the steps of (1) recognizing constraints that define the functional structure, (2) identifying sub-actions that subserve the achievement of structure-dependent goals, (3) explicating modalities as specifics of the movement execution, and (4) assigning functions to actions, sub-actions and modalities. Regarding motor-control theory, a functional approach can be linked to a dynamical-system framework of behavioral shaping, to cognitive models of modular effect-related motor control as well as to explicit concepts of goal setting and goal achievement. Finally, it is shown that a functional approach is of particular help for sports practice in the context of structuring part practice, recognizing functionally equivalent task solutions, finding innovative technique alternatives, distinguishing errors from style, and identifying root causes of movement errors.

  15. A comparison of approaches to estimate the resonance energy

    OpenAIRE

    Zielinski, M.L.; Havenith, R.W.A.; Jenneskens, L. W.; Lenthe, J.H. van

    2010-01-01

    We discuss Ab Initio approaches to calculate the energy lowering (stabilisation) due to aromaticity. We compare the valence bond method and the block-localised wave function approaches to calculate the resonance energy. We conclude that the valence bond approach employs a Pauling–Wheland resonance energy and that the block-localised approach employs a delocalisation criterion. The latter is shown to be more basis set dependent in a series of illustrative calculations.

  16. Efifcient Methods for Approaching Functional Safety to Hardware Systems of Medical Devices

    Institute of Scientific and Technical Information of China (English)

    KIMGi-young; WANGDa-wei; PARKHo-joon; JANG Joong-soon

    2015-01-01

    A medical device is an instrument that includes components, parts, or accessories to diagnose or treat patients. Since the complexity of medical devices has increased in recent years, functional safety and basic safety are required to ensure the overall device safety. Functional safety is part of the overall safety that relates to the equipment under control (EUC) and to the EUC control system that depends on the correct functionality of the electrical/electronic/programmable electronic (E/E/PE) safety-related systems. This study proposes approach methods to functional safety of medical devices for which it is important to correctly identify the safety functions and the safety integrity level (SIL). The relationship between the functional safety and essential performance is identiifed focusing on the safety function. The essential performance of E/E/PE systems is deifned as the safety function of the functional safety. The target SIL of the essential performance is determined according to the potential risk levels, based on the classiifcation rules of medical devices. This approach is applied to the pulse oximeter as a case study. The target SIL for the functionality of the power-failure alarm condition is determined to be SIL1. The target SILs of other functions are determined as SIL2.

  17. A parallel approach of COFFEE objective function to multiple sequence alignment

    Science.gov (United States)

    Zafalon, G. F. D.; Visotaky, J. M. V.; Amorim, A. R.; Valêncio, C. R.; Neves, L. A.; de Souza, R. C. G.; Machado, J. M.

    2015-09-01

    The computational tools to assist genomic analyzes show even more necessary due to fast increasing of data amount available. With high computational costs of deterministic algorithms for sequence alignments, many works concentrate their efforts in the development of heuristic approaches to multiple sequence alignments. However, the selection of an approach, which offers solutions with good biological significance and feasible execution time, is a great challenge. Thus, this work aims to show the parallelization of the processing steps of MSA-GA tool using multithread paradigm in the execution of COFFEE objective function. The standard objective function implemented in the tool is the Weighted Sum of Pairs (WSP), which produces some distortions in the final alignments when sequences sets with low similarity are aligned. Then, in studies previously performed we implemented the COFFEE objective function in the tool to smooth these distortions. Although the nature of COFFEE objective function implies in the increasing of execution time, this approach presents points, which can be executed in parallel. With the improvements implemented in this work, we can verify the execution time of new approach is 24% faster than the sequential approach with COFFEE. Moreover, the COFFEE multithreaded approach is more efficient than WSP, because besides it is slightly fast, its biological results are better.

  18. A nonorthogonal state-interaction approach for matrix product state wave functions

    CERN Document Server

    Knecht, Stefan; Autschbach, Jochen; Reiher, Markus

    2016-01-01

    We present a state-interaction approach for matrix product state (MPS) wave functions in a nonorthogonal molecular orbital basis. Our approach allows us to calculate for example transition and spin-orbit coupling matrix elements between arbitrary electronic states provided that they share the same one-electron basis functions and active orbital space, respectively. The key element is the transformation of the MPS wave functions of different states from a nonorthogonal to a biorthonormal molecular orbital basis representation exploiting a sequence of non-unitary transformations following a proposal by Malmqvist (Int. J. Quantum Chem. 30, 479 (1986)). This is well-known for traditional wave-function parametrizations but has not yet been exploited for MPS wave functions.

  19. Casimir force in brane worlds: Coinciding results from Green's and zeta function approaches

    International Nuclear Information System (INIS)

    Casimir force encodes the structure of the field modes as vacuum fluctuations and so it is sensitive to the extra dimensions of brane worlds. Now, in flat spacetimes of arbitrary dimension the two standard approaches to the Casimir force, Green's function, and zeta function yield the same result, but for brane world models this was only assumed. In this work we show that both approaches yield the same Casimir force in the case of universal extra dimensions and Randall-Sundrum scenarios with one and two branes added by p compact dimensions. Essentially, the details of the mode eigenfunctions that enter the Casimir force in the Green's function approach get removed due to their orthogonality relations with a measure involving the right hypervolume of the plates, and this leaves just the contribution coming from the zeta function approach. The present analysis corrects previous results showing a difference between the two approaches for the single brane Randall-Sundrum; this was due to an erroneous hypervolume of the plates introduced by the authors when using the Green's function. For all the models we discuss here, the resulting Casimir force can be neatly expressed in terms of two four-dimensional Casimir force contributions: one for the massless mode and the other for a tower of massive modes associated with the extra dimensions.

  20. Optimal Investment in Structured Bonds

    DEFF Research Database (Denmark)

    Jessen, Pernille; Jørgensen, Peter Løchte

    2012-01-01

    of the article is to provide possible explanations for the puzzle of why small retail investors hold structured bonds. The investment universe consists of a stock index, a risk-free bank account, and a structured bond containing an option written on another index. We apply expected utility maximization...... and consider different utility functions and trading strategies. Our results show that investors should include structured bonds in their optimal portfolio only if they cannot access the index underlying the option directly and only if the products then provide sufficient diversification to compensate...

  1. Probing the Conformational and Functional Consequences of Disulfide Bond Engineering in Growth Hormone by Hydrogen-Deuterium Exchange Mass Spectrometry Coupled to Electron Transfer Dissociation

    DEFF Research Database (Denmark)

    Seger, Signe T; Breinholt, Jens; Faber, Johan H;

    2015-01-01

    spectrometry (HDX-MS) to map the impact of the new disulfide bond on the conformational dynamics of this new hGH variant. Compared to wild type hGH, the variant exhibits reduced loop dynamics, indicating a stabilizing effect of the introduced disulfide bond. Furthermore, the disulfide bond exhibits longer...... ranging effects, stabilizing a short α-helix quite distant from the mutation sites, but also rendering a part of the α-helical hGH core slightly more dynamic. In the regions where the hGH variant exhibits a different deuterium uptake than the wild type protein, electron transfer dissociation (ETD...

  2. [FUNCTIONAL ANALYTIC PSYCHOTHERAPY: APPROACHES AND SCOPE OF BEHAVIOR THERAPY BASED ON CHANGES IN THE THERAPEUTIC CONTEXT].

    Science.gov (United States)

    Muñoz-Martínez, Amanda M; Coletti, Juan Pablo

    2015-01-01

    Abstract Functional Analytic Psychotherapy (FAP) is a therapeutic approach developed in context. FAP is characterized by use therapeutic relationship and the behaviors emit into it to improve clients daily life functioning. This therapeutic model is supported in behavior analysis principles and contextual functionalism philosophy. FAP proposes that clients behavior in session are functional equivalent with those out of session; therefore, when therapists respond to clients behaviors in session contingently, they promote and increase improvements in the natural setting. This article poses main features of FAP, its philosophical roots, achievements and research challenges to establish FAP as an independent treatment based on the evidence.

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

    Science.gov (United States)

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

    2010-03-01

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

  4. Molecular assembly of highly symmetric molecules under a hydrogen bond framework controlled by alkyl building blocks: a simple approach to fine-tune nanoscale structures.

    Science.gov (United States)

    Tanphibal, Pimsai; Tashiro, Kohji; Chirachanchai, Suwabun

    2016-01-14

    To date, molecular assemblies under the contribution of hydrogen bond in combination with weak interactions and their consequent morphologies have been variously reported; however, how the systematic variation of the structure can fine-tune the morphologies has not yet been answered. The present work finds an answer through highly symmetric molecules, i.e. diamine-based benzoxazine dimers. This type of molecule develops unique molecular assemblies with their networks formed by hydrogen bonds at the terminal, while, at the same time, their hydrogen bonded frameworks are further controlled by the hydrophobic segment at the center of the molecule. When this happens, slight differences in hydrophobic alkyl chain lengths (, , and ) bring a significant change to the molecular assemblies, thus resulting in tunable morphologies, i.e. spheres, needles and dendrites. The superimposition between the crystal lattice obtained from X-ray single crystal analysis and the electron diffraction pattern obtained from transmission electron microscopy allows us to identify the molecular alignment from single molecules to self-assembly until the morphologies developed. The present work, for the first time, shows the case of symmetric molecules, where the hydrophobic building block controls the hydrogen bond patterns, leading to the variation of molecular assemblies with tunable morphologies. PMID:26482133

  5. Mining Functional Modules in Heterogeneous Biological Networks Using Multiplex PageRank Approach.

    Science.gov (United States)

    Li, Jun; Zhao, Patrick X

    2016-01-01

    Identification of functional modules/sub-networks in large-scale biological networks is one of the important research challenges in current bioinformatics and systems biology. Approaches have been developed to identify functional modules in single-class biological networks; however, methods for systematically and interactively mining multiple classes of heterogeneous biological networks are lacking. In this paper, we present a novel algorithm (called mPageRank) that utilizes the Multiplex PageRank approach to mine functional modules from two classes of biological networks. We demonstrate the capabilities of our approach by successfully mining functional biological modules through integrating expression-based gene-gene association networks and protein-protein interaction networks. We first compared the performance of our method with that of other methods using simulated data. We then applied our method to identify the cell division cycle related functional module and plant signaling defense-related functional module in the model plant Arabidopsis thaliana. Our results demonstrated that the mPageRank method is effective for mining sub-networks in both expression-based gene-gene association networks and protein-protein interaction networks, and has the potential to be adapted for the discovery of functional modules/sub-networks in other heterogeneous biological networks. The mPageRank executable program, source code, the datasets and results of the presented two case studies are publicly and freely available at http://plantgrn.noble.org/MPageRank/. PMID:27446133

  6. Mining Functional Modules in Heterogeneous Biological Networks Using Multiplex PageRank Approach.

    Science.gov (United States)

    Li, Jun; Zhao, Patrick X

    2016-01-01

    Identification of functional modules/sub-networks in large-scale biological networks is one of the important research challenges in current bioinformatics and systems biology. Approaches have been developed to identify functional modules in single-class biological networks; however, methods for systematically and interactively mining multiple classes of heterogeneous biological networks are lacking. In this paper, we present a novel algorithm (called mPageRank) that utilizes the Multiplex PageRank approach to mine functional modules from two classes of biological networks. We demonstrate the capabilities of our approach by successfully mining functional biological modules through integrating expression-based gene-gene association networks and protein-protein interaction networks. We first compared the performance of our method with that of other methods using simulated data. We then applied our method to identify the cell division cycle related functional module and plant signaling defense-related functional module in the model plant Arabidopsis thaliana. Our results demonstrated that the mPageRank method is effective for mining sub-networks in both expression-based gene-gene association networks and protein-protein interaction networks, and has the potential to be adapted for the discovery of functional modules/sub-networks in other heterogeneous biological networks. The mPageRank executable program, source code, the datasets and results of the presented two case studies are publicly and freely available at http://plantgrn.noble.org/MPageRank/.

  7. Soliton Solutions of Discrete Complex Ginzburg-Landau Equation via Extended Hyperbolic Function Approach

    Institute of Scientific and Technical Information of China (English)

    LIHua-Mei; LINJi; XUYou-Sheng

    2005-01-01

    In this paper, we extend the hyperbolic function approach for constructing the exact solutions of nonlinear differential-difference equation (NDDE) in a unified way. Applying the extended approach and with the aid of Maple,we have studied the discrete complex Ginzburg-Landau equation (dCGLE). As a result, we find a set of exact solutions which include bright and dark soliton solutions.

  8. A Transfer Function Approach to Structural Vibrations Induced by Thermoacoustic Sources

    OpenAIRE

    Huls, Rob; Boer, de, F.R.; Kok, Jim

    2004-01-01

    To decrease NOx emissions from a combustion system, lean premixed combustion in combination with an annular combustor is used. One of the disadvantages is an increase in sound pressure levels in the combustion system, resulting in an increased excitation of the surrounding structure, the liner. This causes fatigue, which limits the life time of the combustor. To model the interaction between flame, acoustics and structure, a transfer function approach is used. In this approach, the components...

  9. Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies

    Science.gov (United States)

    Oeiras, R. Y.; da Silva, E. Z.

    2014-04-01

    Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials.

  10. Bond length and electric current oscillation of long linear carbon chains: Density functional theory, MpB model, and quantum spin transport studies

    Energy Technology Data Exchange (ETDEWEB)

    Oeiras, R. Y.; Silva, E. Z. da [Institute of Physics “Gleb Wataghin”, University of Campinas-Unicamp, 13083-859 Campinas, SP (Brazil)

    2014-04-07

    Carbon linear atomic chains attached to graphene have experimentally been produced. Motivated by these results, we study the nature of the carbon bonds in these nanowires and how it affects their electrical properties. In the present study we investigate chains with different numbers of atoms and we observe that nanowires with odd number of atoms present a distinct behavior than the ones with even numbers. Using graphene nanoribbons as leads, we identify differences in the quantum transport of the chains with the consequence that even and odd numbered chains have low and high electrical conduction, respectively. We also noted a dependence of current with the wire size. We study this unexpected behavior using a combination of first principles calculations and simple models based on chemical bond theory. From our studies, the electrons of carbon nanowires present a quasi-free electron behavior and this explains qualitatively the high electrical conduction and the bond lengths with unexpected values for the case of odd nanowires. Our study also allows the understanding of the electric conduction dependence with the number of atoms and their parity in the chain. In the case of odd number chains a proposed π-bond (MpB) model describes unsaturated carbons that introduce a mobile π-bond that changes dramatically the structure and transport properties of these wires. Our results indicate that the nature of bonds plays the main role in the oscillation of quantum electrical conduction for chains with even and odd number of atoms and also that nanowires bonded to graphene nanoribbons behave as a quasi-free electron system, suggesting that this behavior is general and it could also remain if the chains are bonded to other materials.

  11. Comparison of the electromagnetic responses of $^{12}$C obtained from the Green's function Monte Carlo and spectral function approaches

    CERN Document Server

    Rocco, Noemi; Benhar, Omar

    2016-01-01

    The electromagnetic responses of carbon obtained from the Green's function Monte Carlo and spectral function approaches using the same dynamical input are compared in the kinematical region corresponding to momentum transfer in the range 300-570 MeV. The results of our analysis, aimed at pinning down the limits of applicability of the approximations involved in the two schemes, indicate that the factorization ansatz underlying the spectral function formalism provides remarkably accurate results down to momentum transfer as low as 300 MeV. On the other hand, it appears that at 570 MeV relativistic corrections to the electromagnetic current not included in the Monte Carlo calculations may play a significant role in the transverse channel.

  12. Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality

    Science.gov (United States)

    Wang, De-Yi; Song, Yan-Peng; Wang, Jun-Sheng; Ge, Xin-Guo; Wang, Yu-Zhong; Stec, Anna A.; Richard Hull, T.

    2009-04-01

    A novel one-step synthetic route, the double in situ approach, is used to produce both TiO2 nanoparticles and polymer (PET), and simultaneously forming a nanocomposite with multi-functionality. The method uses the release of water during esterification to hydrolyze titanium (IV) butoxide (Ti(OBu)4) forming nano-TiO2 in the polymerization vessel. This new approach is of general significance in the preparation of polymer nanocomposites, and will lead to a new route in the synthesis of multi-functional polymer nanocomposites.

  13. Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality

    Directory of Open Access Journals (Sweden)

    Stec Anna

    2009-01-01

    Full Text Available Abstract A novel one-step synthetic route, the double in situ approach, is used to produce both TiO2nanoparticles and polymer (PET, and simultaneously forming a nanocomposite with multi-functionality. The method uses the release of water during esterification to hydrolyze titanium (IV butoxide (Ti(OBu4 forming nano-TiO2in the polymerization vessel. This new approach is of general significance in the preparation of polymer nanocomposites, and will lead to a new route in the synthesis of multi-functional polymer nanocomposites.

  14. An Approach to Function Annotation for Proteins of Unknown Function (PUFs in the Transcriptome of Indian Mulberry.

    Directory of Open Access Journals (Sweden)

    K H Dhanyalakshmi

    Full Text Available The modern sequencing technologies are generating large volumes of information at the transcriptome and genome level. Translation of this information into a biological meaning is far behind the race due to which a significant portion of proteins discovered remain as proteins of unknown function (PUFs. Attempts to uncover the functional significance of PUFs are limited due to lack of easy and high throughput functional annotation tools. Here, we report an approach to assign putative functions to PUFs, identified in the transcriptome of mulberry, a perennial tree commonly cultivated as host of silkworm. We utilized the mulberry PUFs generated from leaf tissues exposed to drought stress at whole plant level. A sequence and structure based computational analysis predicted the probable function of the PUFs. For rapid and easy annotation of PUFs, we developed an automated pipeline by integrating diverse bioinformatics tools, designated as PUFs Annotation Server (PUFAS, which also provides a web service API (Application Programming Interface for a large-scale analysis up to a genome. The expression analysis of three selected PUFs annotated by the pipeline revealed abiotic stress responsiveness of the genes, and hence their potential role in stress acclimation pathways. The automated pipeline developed here could be extended to assign functions to PUFs from any organism in general. PUFAS web server is available at http://caps.ncbs.res.in/pufas/ and the web service is accessible at http://capservices.ncbs.res.in/help/pufas.

  15. An Approach to Function Annotation for Proteins of Unknown Function (PUFs) in the Transcriptome of Indian Mulberry.

    Science.gov (United States)

    Dhanyalakshmi, K H; Naika, Mahantesha B N; Sajeevan, R S; Mathew, Oommen K; Shafi, K Mohamed; Sowdhamini, Ramanathan; N Nataraja, Karaba

    2016-01-01

    The modern sequencing technologies are generating large volumes of information at the transcriptome and genome level. Translation of this information into a biological meaning is far behind the race due to which a significant portion of proteins discovered remain as proteins of unknown function (PUFs). Attempts to uncover the functional significance of PUFs are limited due to lack of easy and high throughput functional annotation tools. Here, we report an approach to assign putative functions to PUFs, identified in the transcriptome of mulberry, a perennial tree commonly cultivated as host of silkworm. We utilized the mulberry PUFs generated from leaf tissues exposed to drought stress at whole plant level. A sequence and structure based computational analysis predicted the probable function of the PUFs. For rapid and easy annotation of PUFs, we developed an automated pipeline by integrating diverse bioinformatics tools, designated as PUFs Annotation Server (PUFAS), which also provides a web service API (Application Programming Interface) for a large-scale analysis up to a genome. The expression analysis of three selected PUFs annotated by the pipeline revealed abiotic stress responsiveness of the genes, and hence their potential role in stress acclimation pathways. The automated pipeline developed here could be extended to assign functions to PUFs from any organism in general. PUFAS web server is available at http://caps.ncbs.res.in/pufas/ and the web service is accessible at http://capservices.ncbs.res.in/help/pufas. PMID:26982336

  16. An improved α-cut approach to transforming fuzzy membership function into basic belief assignment

    Directory of Open Access Journals (Sweden)

    Yang Yi

    2016-08-01

    Full Text Available In practical applications, pieces of evidence originated from different sources might be modeled by different uncertainty theories. To implement the evidence combination under the Dempster–Shafer evidence theory (DST framework, transformations from the other type of uncertainty representation into the basic belief assignment are needed. α-Cut is an important approach to transforming a fuzzy membership function into a basic belief assignment, which provides a bridge between the fuzzy set theory and the DST. Some drawbacks of the traditional α-cut approach caused by its normalization step are pointed out in this paper. An improved α-cut approach is proposed, which can counteract the drawbacks of the traditional α-cut approach and has good properties. Illustrative examples, experiments and related analyses are provided to show the rationality of the improved α-cut approach.

  17. Comparison of two approaches for the treatment of Gutzwiller variational wave functions

    Science.gov (United States)

    Kaczmarczyk, J.

    2015-02-01

    In this work, we analyse the variational problem emerging from the Gutzwiller approach to strongly correlated systems. This problem comprises two main steps: evaluation and minimization of the ground state energy ? for the postulated Gutzwiller Wave Function. We discuss the available methods for evaluating ?, in particular the recently proposed diagrammatic expansion method. We compare the two existing approaches to minimize ?: the standard approach based on the effective single-particle Hamiltonian and the so-called Statistically-consistent Gutzwiller Approximation (SGA). On the example of the superconducting phase analysis, we show that these approaches lead to the same minimum as it should be. However, the calculations within the SGA method are easier to perform and the two approaches allow for a simple cross-check of the obtained results. Finally, we show two ways of solving the equations resulting from the variational procedure, as well as how to incorporate the condition for a fixed number of particles.

  18. High-throughput approaches to understanding gene function and mapping network architecture in bacteria.

    Science.gov (United States)

    Brochado, Ana Rita; Typas, Athanasios

    2013-04-01

    Advances in sequencing technology have provided an unprecedented view of bacterial diversity, along with a daunting number of novel genes. Within this new reality lies the challenge of developing large-scale approaches to assign function to the new genes and place them in pathways. Here, we highlight recent advances on this front, focusing on how high-throughput gene-gene, gene-drug and drug-drug interactions can yield functional and mechanistic inferences in bacteria. PMID:23403119

  19. Approaches to the study of functional activity phagocytic link immune system (review)

    OpenAIRE

    ABDUSHUKUROV ABDURASHI; GULYAMOV NARIMAN; HIETOV ROVSHAN; SADIKOVA NIGORA

    2016-01-01

    Literature data on the role and significance of phagocytic component, in particular, neutrophils in realization of immune response of an organism to antigen are analyzed. A special attention is paid to approaches to evaluation of functional state and reactivity of phagocytes. The most informative and objective method for evaluation of functional state of neutrophils is NBT-test. NBT-test allows to evaluate a potential maximal ability of neutrophils (stimulation test), what part of maximal abi...

  20. Delocalized π state between molecules through a surface confined pseudodihydrogen bond.

    Science.gov (United States)

    Chen, Lan; Li, Hui; Wee, Andrew Thye Shen

    2010-11-26

    When 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) and coronene molecules coadsorb on the Ag(111) surface, one-dimensional PTCDA molecular oligomers with efficient electronic connection via noncovalent bonds are observed by low temperature scanning tunneling microscopy. Density functional theory calculations indicate the neighboring PTCDA molecules form oligomers due to strong PTCDA-metal interactions, which result in overlapping of π orbitals and pseudodihydrogen surface bonds between molecules. Our results provide a potential approach for electron transport from molecule to molecule directly through noncovalent bond. PMID:21231400

  1. Covalent vs Electrostatic Interactions in Rare Earth Systems: A Comparative Study of U(III), U(IV), and U(V) and Nd(III) Bonding Properties by DFT and CAS-PT2 Approaches

    International Nuclear Information System (INIS)

    A description of the electronic Structure of F3UCO, F3NdCO, F4UCO, and F5UCO has been obtained by Complete Active Space second-order perturbation theory CASPT2 calculations using a relativistic effective core potential. These multiconfigurational calculations have been compared to the DFT description combined with a quasi-relativistic ZORA scalar approach. Geometries have been optimized for both levels of calculations and frequencies computed in the DFT formalism. The bonding properties of U(III) have been compared to those of Nd(III) and of higher oxidation states of U(IV, V). Both methodologies are consistent and show a decrease of the covalent character of the U-CO bonding with a higher oxidation state, U(IV) or U(V), as well as its absence for the isoelectronic Nd(III) species. (authors)

  2. Optical characterization of gaps in directly bonded Si compound optics using infrared spectroscopy

    CERN Document Server

    Gully-Santiago, Michael; White, Victor

    2015-01-01

    Silicon direct bonding offers flexibility in the design and development of Si optics by allowing manufacturers to combine subcomponents with a potentially lossless and mechanically stable interface. The bonding process presents challenges in meeting the requirements for optical performance because air gaps at the Si interface cause large Fresnel reflections. Even small (35 nm) gaps reduce transmission through a direct bonded Si compound optic by 4% at $\\lambda = 1.25 \\; \\mu$m at normal incidence. We describe a bond inspection method that makes use of precision slit spectroscopy to detect and measure gaps as small as 14 nm. Our method compares low finesse Fabry-P\\'{e}rot models to high precision measurements of transmission as a function of wavelength. We demonstrate the validity of the approach by measuring bond gaps of known depths produced by microlithography.

  3. Cross Shear Roll Bonding

    DEFF Research Database (Denmark)

    Bay, Niels; Bjerregaard, Henrik; Petersen, Søren. B;

    1994-01-01

    The present paper describes an investigation of roll bonding an AlZn alloy to mild steel. Application of cross shear roll bonding, where the two equal sized rolls run with different peripheral speed, is shown to give better bond strength than conventional roll bonding. Improvements of up to 20......-23% in bond strength are found and full bond strength is obtained at a reduction of 50% whereas 65% is required in case of conventional roll bonding. Pseudo cross shear roll bonding, where the cross shear effect is obtained by running two equal sized rolls with different speed, gives the same results....

  4. Restored glial glutamate transporter EAAT2 function as a potential therapeutic approach for Alzheimer's disease.

    Science.gov (United States)

    Takahashi, Kou; Kong, Qiongman; Lin, Yuchen; Stouffer, Nathan; Schulte, Delanie A; Lai, Liching; Liu, Qibing; Chang, Ling-Chu; Dominguez, Sky; Xing, Xuechao; Cuny, Gregory D; Hodgetts, Kevin J; Glicksman, Marcie A; Lin, Chien-Liang Glenn

    2015-03-01

    Glutamatergic systems play a critical role in cognitive functions and are known to be defective in Alzheimer's disease (AD) patients. Previous literature has indicated that glial glutamate transporter EAAT2 plays an essential role in cognitive functions and that loss of EAAT2 protein is a common phenomenon observed in AD patients and animal models. In the current study, we investigated whether restored EAAT2 protein and function could benefit cognitive functions and pathology in APPSw,Ind mice, an animal model of AD. A transgenic mouse approach via crossing EAAT2 transgenic mice with APPSw,Ind. mice and a pharmacological approach using a novel EAAT2 translational activator, LDN/OSU-0212320, were conducted. Findings from both approaches demonstrated that restored EAAT2 protein function significantly improved cognitive functions, restored synaptic integrity, and reduced amyloid plaques. Importantly, the observed benefits were sustained one month after compound treatment cessation, suggesting that EAAT2 is a potential disease modifier with therapeutic potential for AD. PMID:25711212

  5. Wire bonding in microelectronics

    CERN Document Server

    Harman, George G

    2010-01-01

    Wire Bonding in Microelectronics, Third Edition, has been thoroughly revised to help you meet the challenges of today's small-scale and fine-pitch microelectronics. This authoritative guide covers every aspect of designing, manufacturing, and evaluating wire bonds engineered with cutting-edge techniques. In addition to gaining a full grasp of bonding technology, you'll learn how to create reliable bonds at exceedingly high yields, test wire bonds, solve common bonding problems, implement molecular cleaning methods, and much more. Coverage includes: Ultrasonic bonding systems and technologies, including high-frequency systems Bonding wire metallurgy and characteristics, including copper wire Wire bond testing Gold-aluminum intermetallic compounds and other interface reactions Gold and nickel-based bond pad plating materials and problems Cleaning to improve bondability and reliability Mechanical problems in wire bonding High-yield, fine-pitch, specialized-looping, soft-substrate, and extreme-temperature wire bo...

  6. Analytical approach to the current correlation function in dissipative two-state systems

    Institute of Scientific and Technical Information of China (English)

    Qin WANG; Cheng JIANG; Hang ZHENG

    2008-01-01

    Using the spin-boson model with coupling to Ohmic bath, an analytical approach is developed to study the dynamics of the current correlation function in dissipa-tive two-state systems with the view of understanding the ef-fects of environment and tunneling on the coherent oscillation and the long-time decay of the current correlation function in these systems. An analytic expression of current correlation function is obtained and the results agree very well with that of numerical simulations.

  7. Click chemistry approach to functionalize two-dimensional macromolecules of graphene oxide nanosheets

    Institute of Scientific and Technical Information of China (English)

    Liang Kou; Hongkun He; Chao Gao

    2010-01-01

    A facile “click chemistry” approach to functionalize 2D macromolecules of graphene oxide nanosheets with poly (ethylene glycol) of different molecular weights, polystyrene, palmitic acid and various amino acids was presented. FTIR, TGA, Raman spectroscopy, XPS, XRD, TEM, AFM and SEM were utilized to characterize the products. High degree of functionalization was achieved on the flat surfaces of graphene oxide, affording polymer-grafted 2D brushes and amino acids-immobilized nanosheets, which show improved solubility in organic solvents. The click chemistry strategy reported herein provides a facile and general method for functionalization of graphene oxide with macromolecules and desired biomolecules.

  8. A generating functional approach to the sd-model with strong correlations

    Directory of Open Access Journals (Sweden)

    Yu.A.Izyumov

    2005-01-01

    Full Text Available A Kadanoff-Baym-type generating functional approach, earlier developed by the authors to strongly correlated systems, is applied to the sd-model with strong sd-coupling. Formalism of the Hubbard X-operators was used, and equation for electron Green's function was derived with functional derivatives over external fluctuating fields. Iterations in this equation generate a perturbation theory near the atomic limit. Hartree-Fock type approximation is developed within the framework of this theory, and the problem of a metal-insulator phase transition in sd-model is discussed.

  9. Analysis of DIS structure functions of the nucleon within truncated Mellin moments approach

    CERN Document Server

    Kotlorz, D

    2016-01-01

    We present generalized evolution equations and factorization in terms of the truncated Mellin moments (TMM) of the parton distributions and structure functions. We illustrate the $x$ and $Q^2$ dependence of TMM in the polarized case. Using the TMM approach we compare the integrals of $g_1$ with HERMES and COMPASS data from the limited $x$-ranges.

  10. An approach for functional safety improvement of an existing automotive system

    NARCIS (Netherlands)

    Khabbaz Saberi, A.; Luo, Y.; Pawel Cichosz, F.; Brand, M. van den; Jansen, S.T.H.

    2015-01-01

    Safety of automotive systems is becoming more involved, specially for the case of autonomous vehicles. The ISO 26262 standard offers a systematic approach for designing a safe road vehicle (or subsystems of a car) from design phase through its production. However, providing functional safety (accord

  11. Integrating Formal and Functional Approaches to Language Teaching in French Immersion: An Experimental Study.

    Science.gov (United States)

    Day, Elaine M.; Shapson, Stan M.

    2001-01-01

    Evaluated the effect on French language proficiency of an integrated formal, analytic and functional, communicative approach to second language teaching in the immersion classroom. Impetus for the study arises from previous research indicating that immersion children show persistent weaknesses in their grammatical skills despite the fluent,…

  12. THE MODELLING OF MEDICAL INSURANCE WITH USE OF SYSTEM AND STRUCTURAL FUNCTIONAL APPROACH

    OpenAIRE

    Yevtushenko, T.

    2009-01-01

    The system of medical insurance management (the motive of insurance services, the model of working out and realization of insurance services, risk-management of insurance services). The information models of making decisions in medical insurance realization's based on the principles of system and structural functional approach are worked out.

  13. Functional approach to a Class II patient with upper first molar impaction

    Directory of Open Access Journals (Sweden)

    Giacomo D′Orlandi

    2014-01-01

    Full Text Available The lack of the left first molar maxillary and the left second molar maxillary, caused respectively by impaction and agenesis is a very rare case, which determines an important occlusal imbalance and asymmetrical mandible movement. A gnatologic and functional orthodontic approach were planned to improve the retrognathic mandible and the muscular activity using kinesiograph and electromyography.

  14. Novel Vaccine Approach Achieves “Functional Cure” of AIDS Virus in Monkeys | Poster

    Science.gov (United States)

    By Frank Blanchard, Staff Writer, and Jeff Lifson, Guest Writer Scientists at the Oregon Health & Science University and the AIDS and Cancer Virus Program of the Frederick National Laboratory for Cancer Research have used a novel vaccine approach to achieve a “functional cure” and apparent eradication of infection with a monkey version of the AIDS virus.

  15. Fragment approach to constrained density functional theory calculations using Daubechies wavelets

    Energy Technology Data Exchange (ETDEWEB)

    Ratcliff, Laura E., E-mail: lratcliff@anl.gov [Argonne Leadership Computing Facility, Argonne National Laboratory, Lemont, Illinois 60439 (United States); Université de Grenoble Alpes, CEA, INAC-SP2M, L-Sim, F-38000 Grenoble (France); Genovese, Luigi; Mohr, Stephan; Deutsch, Thierry [Université de Grenoble Alpes, CEA, INAC-SP2M, L-Sim, F-38000 Grenoble (France)

    2015-06-21

    In a recent paper, we presented a linear scaling Kohn-Sham density functional theory (DFT) code based on Daubechies wavelets, where a minimal set of localized support functions are optimized in situ and therefore adapted to the chemical properties of the molecular system. Thanks to the systematically controllable accuracy of the underlying basis set, this approach is able to provide an optimal contracted basis for a given system: accuracies for ground state energies and atomic forces are of the same quality as an uncontracted, cubic scaling approach. This basis set offers, by construction, a natural subset where the density matrix of the system can be projected. In this paper, we demonstrate the flexibility of this minimal basis formalism in providing a basis set that can be reused as-is, i.e., without reoptimization, for charge-constrained DFT calculations within a fragment approach. Support functions, represented in the underlying wavelet grid, of the template fragments are roto-translated with high numerical precision to the required positions and used as projectors for the charge weight function. We demonstrate the interest of this approach to express highly precise and efficient calculations for preparing diabatic states and for the computational setup of systems in complex environments.

  16. Fragment approach to constrained density functional theory calculations using Daubechies wavelets

    International Nuclear Information System (INIS)

    In a recent paper, we presented a linear scaling Kohn-Sham density functional theory (DFT) code based on Daubechies wavelets, where a minimal set of localized support functions are optimized in situ and therefore adapted to the chemical properties of the molecular system. Thanks to the systematically controllable accuracy of the underlying basis set, this approach is able to provide an optimal contracted basis for a given system: accuracies for ground state energies and atomic forces are of the same quality as an uncontracted, cubic scaling approach. This basis set offers, by construction, a natural subset where the density matrix of the system can be projected. In this paper, we demonstrate the flexibility of this minimal basis formalism in providing a basis set that can be reused as-is, i.e., without reoptimization, for charge-constrained DFT calculations within a fragment approach. Support functions, represented in the underlying wavelet grid, of the template fragments are roto-translated with high numerical precision to the required positions and used as projectors for the charge weight function. We demonstrate the interest of this approach to express highly precise and efficient calculations for preparing diabatic states and for the computational setup of systems in complex environments

  17. Bond Graph Modeling and Simulation of Mechatronic Systems

    DEFF Research Database (Denmark)

    Habib, Tufail; Nielsen, Kjeld; Jørgensen, Kaj Asbjørn

    2012-01-01

    One of the demanding steps in the design and development of Mechatronic systems is to develop the initial model to visualize the response of a system. The Bond Graph (BG) method is a graphical approach for the design of multidomain systems. That is ideal for visualizing the essential characterist......One of the demanding steps in the design and development of Mechatronic systems is to develop the initial model to visualize the response of a system. The Bond Graph (BG) method is a graphical approach for the design of multidomain systems. That is ideal for visualizing the essential...... characteristics of a system. This paper explores the BG method as a modeling approach to develop Mechatronic systems; a case study about the Radar Antenna pedestal drive system is comprehensively addressed. Flow of energy between different functional elements of the system and their causalities are analyzed...

  18. Analyzing Rice distributed functional magnetic resonance imaging data: a Bayesian approach

    International Nuclear Information System (INIS)

    Analyzing functional MRI data is often a hard task due to the fact that these periodic signals are strongly disturbed with noise. In many cases, the signals are buried under the noise and not visible, such that detection is quite impossible. However, it is well known that the amplitude measurements of such disturbed signals follow a Rice distribution which is characterized by two parameters. In this paper, an alternative Bayesian approach is proposed to tackle this two-parameter estimation problem. By incorporating prior knowledge into a mathematical framework, the drawbacks of the existing methods (i.e. the maximum likelihood approach and the method of moments) can be overcome. The performance of the proposed Bayesian estimator is analyzed theoretically and illustrated through simulations. Finally, the developed approach is successfully applied to measurement data for the analysis of functional MRI

  19. Portfolio Management for a Random Field of Bond Returns

    OpenAIRE

    Vladislav Kargin

    2003-01-01

    A new method of bond portfolio optimization is described. The method is based on stochastic string models of bond returns. It is shown how to approximate the bond return correlation function with Padé approximations and how to compute the optimal portfolio allocation using Wiener-Hopf factorization. The technique is illustrated with an example of the Treasury bond portfolio.

  20. A real-space stochastic density matrix approach for density functional electronic structure.

    Science.gov (United States)

    Beck, Thomas L

    2015-12-21

    The recent development of real-space grid methods has led to more efficient, accurate, and adaptable approaches for large-scale electrostatics and density functional electronic structure modeling. With the incorporation of multiscale techniques, linear-scaling real-space solvers are possible for density functional problems if localized orbitals are used to represent the Kohn-Sham energy functional. These methods still suffer from high computational and storage overheads, however, due to extensive matrix operations related to the underlying wave function grid representation. In this paper, an alternative stochastic method is outlined that aims to solve directly for the one-electron density matrix in real space. In order to illustrate aspects of the method, model calculations are performed for simple one-dimensional problems that display some features of the more general problem, such as spatial nodes in the density matrix. This orbital-free approach may prove helpful considering a future involving increasingly parallel computing architectures. Its primary advantage is the near-locality of the random walks, allowing for simultaneous updates of the density matrix in different regions of space partitioned across the processors. In addition, it allows for testing and enforcement of the particle number and idempotency constraints through stabilization of a Feynman-Kac functional integral as opposed to the extensive matrix operations in traditional approaches. PMID:25969148

  1. A functional genomics approach using metabolomics and in silico pathway analysis

    DEFF Research Database (Denmark)

    Förster, Jochen; Gombert, Andreas Karoly; Nielsen, Jens

    2002-01-01

    In the field of functional genomics increasing effort is being undertaken to analyze the function of orphan genes using metabolome data. Improved analytical equipment allows screening simultaneously for a high number of metabolites. Such metabolite profiles are analyzed using multivariate data...... analysis techniques and changes in the genotype will in many cases lead to different metabolite profiles. Here, a theoretical framework that may be applied to identify the function of orphan genes is presented. The approach is based on a combination of metabolome analysis combined with in silico pathway...... analysis. Pathway analysis may be carried out using convex analysis and a change in the active pathway structure of deletion mutants expressed in a different metabolite profile may disclose the function or the functional class of an orphan gene. The concept is illustrated using a simplified model for...

  2. Planning Approach to Organisational and Methodical Provision of Formation and Functioning of Logistic Systems of Enterprises

    Directory of Open Access Journals (Sweden)

    Kolodizyeva Tetyana O.

    2013-12-01

    Full Text Available The article analyses factors of external and internal environment of enterprises that influence the process of formation of logistic systems and justifies expediency of use of the planning approach to development of the organisational and methodical provision of functioning of logistic systems of enterprises. The article offers to conduct development of organisational and methodical provision of formation of functioning of logistic systems with the use of not one but several methodological approaches: situational, process, functional and planning. The conducted analysis allowed composing a basic project, which could be laid in the foundation of formation of a logistic system by any enterprise for meeting requirements of the planning triangle: content / borders, time, cost, taking into consideration the forth limitation – quality.

  3. Fast approach to infrared image restoration based on shrinkage functions calibration

    Science.gov (United States)

    Zhang, Chengshuo; Shi, Zelin; Xu, Baoshu; Feng, Bin

    2016-05-01

    High-quality image restoration in real time is a challenge for infrared imaging systems. We present a fast approach to infrared image restoration based on shrinkage functions calibration. Rather than directly modeling the prior of sharp images to obtain the shrinkage functions, we calibrate them for restoration directly by using the acquirable sharp and blurred image pairs from the same infrared imaging system. The calibration method is employed to minimize the sum of squared errors between sharp images and restored images from the blurred images. Our restoration algorithm is noniterative and its shrinkage functions are stored in the look-up tables, so an architecture solution of pipeline structure can work in real time. We demonstrate the effectiveness of our approach by testing its quantitative performance from simulation experiments and its qualitative performance from a developed wavefront coding infrared imaging system.

  4. A modular approach to introduce function into single-chain polymeric nanoparticles.

    Science.gov (United States)

    Huerta, Elisa; van Genabeek, Bas; Stals, Patrick J M; Meijer, E W; Palmans, Anja R A

    2014-08-01

    Here, a modular approach is reported to introduce a specific function into single-chain polymeric nanoparticles (SCPNs). Hereto, an amphiphilic polymer with pendant benzene-1,3,5-tricarboxamide (BTA) units is mixed with a "free" BTA that contains a functional group, either a fluorescent naphthalimide or a catalytically active l-proline. Taking advantage of hydrophobic interactions and self-recognition properties of the BTA units, the "free" BTAs are captured into the interior of the SCPN in water as evidenced by fluorescence studies. To illustrate that function can be readily introduced using a modular approach, l-proline-based BTAs are incorporated to procure a catalytically active SCPN in water. The aldol reaction between p-nitrobenzaldehyde and cyclohexanone shows good conversions at low catalyst loadings and substrate concentrations, and high stereoselectivities are obtained (de = 91% and ee = 98%). PMID:24962087

  5. Form factor approach to the asymptotic behavior of correlation functions in critical models

    CERN Document Server

    Kitanine, N; Maillet, J M; Slavnov, N A; Terras, V

    2011-01-01

    We propose a form factor approach for the computation of the large distance asymptotic behavior of correlation functions in quantum critical (integrable) models. In the large distance regime we reduce the summation over all excited states to one over the particle/hole excitations lying on the Fermi surface in the thermodynamic limit. We compute these sums, over the so-called critical form factors, exactly. Thus we obtain the leading large distance behavior of each oscillating harmonic of the correlation function asymptotic expansion, including the corresponding amplitudes. Our method is applicable to a wide variety of integrable models and yields precisely the results stemming from the Luttinger liquid approach, the conformal field theory predictions and our previous analysis of the correlation functions from their multiple integral representations. We argue that our scheme applies to a general class of non-integrable quantum critical models as well.

  6. Density functional theory approach for calculation of dielectric properties of warm dense matter

    Science.gov (United States)

    Saitov, Ilnur

    2015-06-01

    The reflectivity of shocked xenon was measured in the experiments of Mintsev and Zaporoghets for wavelength 1064 nm. But there is no adequate theoretical explanation of these reflectivity results in the framework of the standard methods of nonideal plasma theory. The assumption of significant width to the shock front gives a good agreement with the experimental data. However, there are no evidences of this effect in the experiment. Reflectivity of shocked compressed xenon plasma is calculated in the framework of the density functional theory approach as in. Dependencies on the frequency of incident radiation and on the plasma density are analyzed. The Fresnel formula for the reflectivity is used. The longitudinal expression in the long wavelength limit is applied for the calculation of the imaginary part of the dielectric function. The real part of the dielectric function is calculated by means of the Kramers-Kronig transformation. The approach for the calculation of plasma frequency is developed.

  7. A textural approach based on Gabor functions for texture edge detection in ultrasound images.

    Science.gov (United States)

    Chen, C M; Lu, H H; Han, K C

    2001-04-01

    Edge detection is an important, but difficult, step in quantitative ultrasound (US) image analysis. In this paper, we present a new textural approach for detecting a class of edges in US images; namely, the texture edges with a weak regional mean gray-level difference (RMGD) between adjacent regions. The proposed approach comprises a vision model-based texture edge detector using Gabor functions and a new texture-enhancement scheme. The experimental results on the synthetic edge images have shown that the performances of the four tested textural and nontextural edge detectors are about 20%-95% worse than that of the proposed approach. Moreover, the texture enhancement may improve the performance of the proposed texture edge detector by as much as 40%. The experiments on 20 clinical US images have shown that the proposed approach can find reasonable edges for real objects of interest with the performance of 0.4 +/- 0.08 in terms of the Pratt's figure.

  8. Diagnosis of Switching Systems using Hybrid Bond Graph

    Directory of Open Access Journals (Sweden)

    Taher Mekki

    2013-01-01

    Full Text Available Hybrid Bond Graph (HBG is a Bond Graph-based modelling approach which provides an effective tool not only for dynamic modeling but also for fault detection and isolation (FDI of switching systems. Bond graph (BG has been proven useful for FDI for continuous systems. In addition, BG provides the causal relations between systems variables which allow FDI algorithms to be developed systematically from the graph. There are many methods that exploit structural relations and functional redundancy in the system model to find efficient solutions for the residual generation and residual evaluation steps in FDI of switching systems. This paper describes two different techniques, quantitative and qualitative, based on common modelling approach that employs HBG. In quantitative approach, global analytical redundancy relationships (GARRs are derived from the HBG model with a specified causality assignment procedure. GARRs describe the system behaviour at all of its operating modes. In qualitative approach, functional redundancy can be captured by a Temporal Causal Graph (TCG, a directed graph that may include temporal information.

  9. Global land model development: time to shift from a plant functional type to a plant functional trait approach

    Science.gov (United States)

    Reich, P. B.; Butler, E. E.

    2015-12-01

    This project will advance global land models by shifting from the current plant functional type approach to one that better utilizes what is known about the importance and variability of plant traits, within a framework of simultaneously improving fundamental physiological relations that are at the core of model carbon cycling algorithms. Existing models represent the global distribution of vegetation types using the Plant Functional Typeconcept. Plant Functional Types are classes of plant species with similar evolutionary and life history withpresumably similar responses to environmental conditions like CO2, water and nutrient availability. Fixedproperties for each Plant Functional Type are specified through a collection of physiological parameters, or traits.These traits, mostly physiological in nature (e.g., leaf nitrogen and longevity) are used in model algorithms to estimate ecosystem properties and/or drive calculated process rates. In most models, 5 to 15 functional types represent terrestrial vegetation; in essence, they assume there are a total of only 5 to 15 different kinds of plants on the entire globe. This assumption of constant plant traits captured within the functional type concept has serious limitations, as a single set of traits does not reflect trait variation observed within and between species and communities. While this simplification was necessary decades past, substantial improvement is now possible. Rather than assigning a small number of constant parameter values to all grid cells in a model, procedures will be developed that predict a frequency distribution of values for any given grid cell. Thus, the mean and variance, and how these change with time, will inform and improve model performance. The trait-based approach will improve land modeling by (1) incorporating patterns and heterogeneity of traits into model parameterization, thus evolving away from a framework that considers large areas of vegetation to have near identical trait

  10. A Multimodal Approach for Determining Brain Networks by Jointly Modeling Functional and Structural Connectivity

    Directory of Open Access Journals (Sweden)

    Wenqiong eXue

    2015-02-01

    Full Text Available Recent innovations in neuroimaging technology have provided opportunities for researchers to investigate connectivity in the human brain by examining the anatomical circuitry as well as functional relationships between brain regions. Existing statistical approaches for connectivity generally examine resting-state or task-related functional connectivity (FC between brain regions or separately examine structural linkages. As a means to determine brain networks, we present a unified Bayesian framework for analyzing FC utilizing the knowledge of associated structural connections, which extends an approach by Patel et al.(2006a that considers only functional data. We introduce an FC measure that rests upon assessments of functional coherence between regional brain activity identified from functional magnetic resonance imaging (fMRI data. Our structural connectivity (SC information is drawn from diffusion tensor imaging (DTI data, which is used to quantify probabilities of SC between brain regions. We formulate a prior distribution for FC that depends upon the probability of SC between brain regions, with this dependence adhering to structural-functional links revealed by our fMRI and DTI data. We further characterize the functional hierarchy of functionally connected brain regions by defining an ascendancy measure that compares the marginal probabilities of elevated activity between regions. In addition, we describe topological properties of the network, which is composed of connected region pairs, by performing graph theoretic analyses. We demonstrate the use of our Bayesian model using fMRI and DTI data from a study of auditory processing. We further illustrate the advantages of our method by comparisons to methods that only incorporate functional information.

  11. Covalently Bonded Polyaniline and para-phenylenediamine Functionalized Graphene Oxide: How the Conductive Two-dimensional Nanostructure Influences the Electrochromic Behaviors of Polyaniline

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: Polyaniline (PANI) was attached onto the reduced graphene oxide (rGO) sheets through copolymerization of aniline with a para-phenylenediamine (PPD) functionalized graphene oxide (GO-PPD) using the poly(styrene sulfonate) (PSS) as the macromolecular dopant agent to produce a water-dispersible electrochromic material. The structures and the morphologies analysis confirm that the final electrochromic materials (rGO-PANI) are the mixture of PANI/PSS and the covalently bonded rGO-PANI (rGO-PANI hybrid). The rGO-PANI hybrid can be found to form a parallel arrangement to the substrate in the spin-coated film. This parallel arrangement of the layered two-dimensional nanostructure of rGO-PANI hybrid may narrow the ion transportation pathways of the exchanged ions, which will result in a high charge transfer resistance and slow switching speed. Meanwhile, with the conductive rGO added, the electrical conductivity of the electrochromic layer will be increased, which will benefit to low charge transfer resistance and high optical contrast. So the conductive two-dimensional nanostructure has a double-face influence on the electrochromic performances of PANI, which include a positive influence on the electrical conductivity and a negative influence on the ion diffusion. The overall influences depend on the loading amount of GO-PPD. With 4 wt.% GO-PPD feeding, the optical contrast was enhanced by 36% from 0.38 for PANI/PSS to 0.52 for rGO-PANI-3, while the coloration time was almost same as that of PANI/PSS and the bleaching time was decreased by ∼20% from 9.1s for PANI/PSS to 7.4s for rGO-PANI-3. The electrochemical tests showed that with the increasing of GO-PPD loading, the peak currents of cyclic voltammetry (CV) curves were increased, and the peak locations shifted to the positive potential for oxidation peak and the negative potential for reduction peak, respectively, which confirmed that the double-face influences of rGO-PANI on the

  12. Carbon K-edge X-ray absorption spectroscopy and time-dependent density functional theory examination of metal-carbon bonding in metallocene dichlorides.

    Science.gov (United States)

    Minasian, Stefan G; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Kozimor, Stosh A; Martin, Richard L; Shuh, David K; Tyliszczak, Tolek; Vernon, Louis J

    2013-10-01

    Metal-carbon covalence in (C5H5)2MCl2 (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a1* and 1b2* orbitals. The peak intensities, which are directly related to the M-(C5H5) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (C5H5)2TiCl2 to 0.31(3) and 0.75(8) for (C5H5)2ZrCl2, and finally to 0.54(5) and 0.83(8) for (C5H5)2HfCl2. The experimental trend toward increased peak intensity for transitions associated with 1a1* and 1b2* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (C5H5)2TiCl2; 0.21 and 0.73, (C5H5)2ZrCl2; 0.35 and 0.69, (C5H5)2HfCl2] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a1* and 1b2* orbitals [8.2 and 23.4%, (C5H5)2TiCl2; 15.3 and 39.7%, (C5H5)2ZrCl2; 20.1 and 50.9%, (C5H5)2HfCl2]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M-Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands.

  13. Optogenetics in the cerebellum: Purkinje cell-specific approaches for understanding local cerebellar functions.

    Science.gov (United States)

    Tsubota, Tadashi; Ohashi, Yohei; Tamura, Keita

    2013-10-15

    The cerebellum consists of the cerebellar cortex and the cerebellar nuclei. Although the basic neuronal circuitry of the cerebellar cortex is uniform everywhere, anatomical data demonstrate that the input and output relationships of the cortex are spatially segregated between different cortical areas, which suggests that there are functional distinctions between these different areas. Perturbation of cerebellar cortical functions in a spatially restricted fashion is thus essential for investigating the distinctions among different cortical areas. In the cerebellar cortex, Purkinje cells are the sole output neurons that send information to downstream cerebellar and vestibular nuclei. Therefore, selective manipulation of Purkinje cell activities, without disturbing other neuronal types and passing fibers within the cortex, is a direct approach to spatially restrict the effects of perturbations. Although this type of approach has for many years been technically difficult, recent advances in optogenetics now enable selective activation or inhibition of Purkinje cell activities, with high temporal resolution. Here we discuss the effectiveness of using Purkinje cell-specific optogenetic approaches to elucidate the functions of local cerebellar cortex regions. We also discuss what improvements to current methods are necessary for future investigations of cerebellar functions to provide further advances.

  14. An Approach to Formulation of FNLP with Complex Piecewise Linear Membership Functions

    Institute of Scientific and Technical Information of China (English)

    闻博; 李宏光

    2014-01-01

    Traditionally, extra binary variables are demanded to formulate a fuzzy nonlinear programming (FNLP) problem with piecewise linear membership functions (PLMFs). However, this kind of methodology usually suffers increasing computational burden associated with formulation and solution, particularly in the face of complex PLMFs. Motivated by these challenges, this contribution introduces a novel approach free of additional binary variables to formulate FNLP with complex PLMFs, leading to superior performance in reducing computational complexity as well as simplifying formulation. A depth discussion about the approach is conducted in this paper, along with a numerical case study to demonstrate its potential benefits.

  15. Channel based generating function approach to the stochastic Hodgkin-Huxley neuronal system

    Science.gov (United States)

    Ling, Anqi; Huang, Yandong; Shuai, Jianwei; Lan, Yueheng

    2016-03-01

    Internal and external fluctuations, such as channel noise and synaptic noise, contribute to the generation of spontaneous action potentials in neurons. Many different Langevin approaches have been proposed to speed up the computation but with waning accuracy especially at small channel numbers. We apply a generating function approach to the master equation for the ion channel dynamics and further propose two accelerating algorithms, with an accuracy close to the Gillespie algorithm but with much higher efficiency, opening the door for expedited simulation of noisy action potential propagating along axons or other types of noisy signal transduction.

  16. Stable alkanes containing very long carbon-carbon bonds.

    Science.gov (United States)

    Fokin, Andrey A; Chernish, Lesya V; Gunchenko, Pavel A; Tikhonchuk, Evgeniya Yu; Hausmann, Heike; Serafin, Michael; Dahl, Jeremy E P; Carlson, Robert M K; Schreiner, Peter R

    2012-08-22

    The metal-induced coupling of tertiary diamondoid bromides gave highly sterically congested hydrocarbon (hetero)dimers with exceptionally long central C-C bonds of up to 1.71 Å in 2-(1-diamantyl)[121]tetramantane. Yet, these dimers are thermally very stable even at temperatures above 200 °C, which is not in line with common C-C bond length versus bond strengths correlations. We suggest that the extraordinary stabilization arises from numerous intramolecular van der Waals attractions between the neighboring H-terminated diamond-like surfaces. The C-C bond rotational dynamics of 1-(1-adamantyl)diamantane, 1-(1-diamantyl)diamantane, 2-(1-adamantyl)triamantane, 2-(1-diamantyl)triamantane, and 2-(1-diamantyl)[121]tetramantane were studied through variable-temperature (1)H- and (13)C NMR spectroscopies. The shapes of the inward (endo) CH surfaces determine the dynamic behavior, changing the central C-C bond rotation barriers from 7 to 33 kcal mol(-1). We probe the ability of popular density functional theory (DFT) approaches (including BLYP, B3LYP, B98, B3LYP-Dn, B97D, B3PW91, BHandHLYP, B3P86, PBE1PBE, wB97XD, and M06-2X) with 6-31G(d,p) and cc-pVDZ basis sets to describe such an unusual bonding situation. Only functionals accounting for dispersion are able to reproduce the experimental geometries, while most DFT functionals are able to reproduce the experimental rotational barriers due to error cancellations. Computations on larger diamondoids reveal that the interplay between the shapes and the sizes of the CH surfaces may even allow the preparation of open-shell alkyl radical dimers (and possibly polymers) that are strongly held together exclusively by dispersion forces. PMID:22835264

  17. LAMMPS Framework for Dynamic Bonding and an Application Modeling DNA

    DEFF Research Database (Denmark)

    Svaneborg, Carsten

    2012-01-01

    and bond types. When breaking bonds, all angular and dihedral interactions involving broken bonds are removed. The framework allows chemical reactions to be modeled, and use it to simulate a simplistic, coarse-grained DNA model. The resulting DNA dynamics illustrates the power of the present framework.......We have extended the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) to support directional bonds and dynamic bonding. The framework supports stochastic formation of new bonds, breakage of existing bonds, and conversion between bond types. Bond formation can be controlled to...... limit the maximal functionality of a bead with respect to various bond types. Concomitant with the bond dynamics, angular and dihedral interactions are dynamically introduced between newly connected triplets and quartets of beads, where the interaction type is determined from the local pattern of bead...

  18. A MDA approach for defining WS-Policy semantic non-functional properties

    CERN Document Server

    Belouadha, Fatima-Zahra; Roudies, Ounsa

    2012-01-01

    A lot of works has been especially interested to the functional aspect of Web services. Nevertheless, it is necessary to describe their non-functional properties such as the security characteristics and the quality of service. The WS-Policy standard was recommended in 2007 to describe Web services policies including the non-functional properties. However, it doesn't provide any information of their meaning necessary for automatic processes. In this paper, we propose a Model Driven Architecture approach founded on W3C standards to generate WSDL language based files including semantic policies. We use a package of WSDL and WS-Policy profiles and transformations rules to generate Web services interfaces files including policies. We extend a XML schema profile according to SAWSDL standard to define semantic non-functional properties domains. This work contributes to minimize the development cost of Web services including semantic policies. Moreover, the generated services can be automatically processed in discove...

  19. The Breathing Orbital Valence Bond Method in Diffusion Monte Carlo: C-H Bond Dissociation ofAcetylene

    Energy Technology Data Exchange (ETDEWEB)

    Domin, D.; Braida, Benoit; Lester Jr., William A.

    2008-05-30

    This study explores the use of breathing orbital valence bond (BOVB) trial wave functions for diffusion Monte Carlo (DMC). The approach is applied to the computation of the carbon-hydrogen (C-H) bond dissociation energy (BDE) of acetylene. DMC with BOVB trial wave functions yields a C-H BDE of 132.4 {+-} 0.9 kcal/mol, which is in excellent accord with the recommended experimental value of 132.8 {+-} 0.7 kcal/mol. These values are to be compared with DMC results obtained with single determinant trial wave functions, using Hartree-Fock orbitals (137.5 {+-} 0.5 kcal/mol) and local spin density (LDA) Kohn-Sham orbitals (135.6 {+-} 0.5 kcal/mol).

  20. Nanoparticle/Polymer Nanocomposite Bond Coat or Coating

    Science.gov (United States)

    Miller, Sandi G.

    2011-01-01

    This innovation addresses the problem of coatings (meant to reduce gas permeation) applied to polymer matrix composites spalling off in service due to incompatibility with the polymer matrix. A bond coat/coating has been created that uses chemically functionalized nanoparticles (either clay or graphene) to create a barrier film that bonds well to the matrix resin, and provides an outstanding barrier to gas permeation. There is interest in applying clay nanoparticles as a coating/bond coat to a polymer matrix composite. Often, nanoclays are chemically functionalized with an organic compound intended to facilitate dispersion of the clay in a matrix. That organic modifier generally degrades at the processing temperature of many high-temperature polymers, rendering the clay useless as a nano-additive to high-temperature polymers. However, this innovation includes the use of organic compounds compatible with hightemperature polymer matrix, and is suitable for nanoclay functionalization, the preparation of that clay into a coating/bondcoat for high-temperature polymers, the use of the clay as a coating for composites that do not have a hightemperature requirement, and a comparable approach to the preparation of graphene coatings/bond coats for polymer matrix composites.

  1. The Valence Bond Interpretation of Molecular Geometry.

    Science.gov (United States)

    Smith, Derek W.

    1980-01-01

    Presents ways in which the valence bond (VB) theory describes the bonding and geometry of molecules, following directly from earlier principles laid down by Pauling and others. Two other theories (molecular orbital approach and valence shell electron pair repulsion) are discussed and compared to VB. (CS)

  2. Organocatalysis by hydrogen-bonding: a new approach to controlled/living polymerization of α-amino acid N-carboxyanhydrides

    KAUST Repository

    Zhao, Wei

    2015-01-01

    A new method, based on hydrogen-bonding organocatalysis, was developed to achieve living ring-opening polymerization of N-carboxyanhydride of α-amino acids using aminoalcohols as initiators in the presence of N,N′-bis[3,5-bis(trifluoromethyl)phenyl]thiourea (TU-S). The thiourea provides, through hydrogen bonding, simultaneous activation of NCA monomers/reversible deactivation of polymer chain-ends/silencing of the tertiary amine and thus allows the polymerization to proceed in a highly controllable mode. For example, by using N,N-dimethyl ethanolamine (DMEA), as an initiator in the presence of TU-S, a series of well-defined linear polypeptides with differently designed Mns (3.01 × 104-18.10 × 104) and low PDI values (1.02-1.05) were successfully synthesized. This general strategy was also extended to the synthesis of well-defined di- and multi-armed polypeptides by using di-, tri-, or tetra-aminoalcohol initiators (methyldiethanolamine (MDEA), triethanolamine (TEA) or N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine (THEED)) in the presence of TU-S. © The Royal Society of Chemistry 2015.

  3. An Information-Theoretic Approach to Effective Inference for Z-functionals

    Institute of Scientific and Technical Information of China (English)

    Chang Chun WU; Run Chu ZHANG

    2009-01-01

    In this paper, through an information-theoretic approach, we construct estimations and confidence intervals of Z-functionals involving finite population and with the presence of auxiliary information. In particular, we give a method of estimating the variance of finite population with known mean. The modified estimates and confidence intervals for Z-functionals can adequately use the auxiliary information, at least not worse than what the standard ones do. A simulation study is presented to assess the performance of the modified estimates for the finite sample case.

  4. The Quality of Life and relevant Approaches based on Capabilities and Functionalities

    Directory of Open Access Journals (Sweden)

    Matei Șimandan

    2014-12-01

    Full Text Available Recent research regarding the quality of life developed different approaches concerning the use of objective and subjective indicators, as well as the relevance of hypotheses, propositions and methods of analysis or of evaluation. Starting from the conceptual difficulties regarding the term of ‘quality of life’, this article focuses upon the contributions of Amartya Sen on the relationships between resources, liberties, capabilities, functionalities and human development. A separate section attempts to capture the shift of accent from the approaches of a quantitative type towards those of a qualitative type, founded on capabilities, functionalities, and the factors of conversion of resources into elements of quality of subjective life. The following sections are consecrated to the contributions to the development of the model proposed by Amartya Sen and to the reception of this model by a few specialists in the field, as well as to its relevance within scientific research and the foundation of public policies.

  5. A new integrated approach for dye removal from wastewater by polyoxometalates functionalized membranes.

    Science.gov (United States)

    Yao, Lei; Zhang, Lizhi; Wang, Rong; Chou, Shuren; Dong, ZhiLi

    2016-01-15

    Membrane technique is a promising way for the removal of dyes from wastewater. A unique approach combining both the adsorptive and the catalytic membrane processes was proposed on the basis of a new functionalized membrane. The membrane integrating both the adsorptive and catalytic activities was developed by introducing polyoxometalates (POMs) as an ideal candidate for the membrane functionalization via a novel sol-gel method. A two-step protocol, adsorptive separation and catalytic degradation, was designed for dye removal, realizing an excellent dye rejection with easy and economic membrane regeneration through simply soaking the membrane in a limited volume of dilute oxidant solution. This approach is feasible and versatile owing to the flexible selection of distinct POMs and design of catalytic degradation routes as required. As a result, the current research provides insight into a new methodology of the membrane technique in dye removal applications. PMID:26410275

  6. Control of a Biped Robot by Total Rate of Angular Momentum Using the Task Function Approach

    Directory of Open Access Journals (Sweden)

    J. A. Rojas-Estrada

    2005-01-01

    Full Text Available In this work we address the control problem of biped robots by using the task function approach. A problem arrives when one of the feet is in contact with the ground, which presents imperfections. There is then the possibility that the biped robot undergoes a fall. It is difficult to track any trajectory due to the presence of unevenness on the ground. What we propose is to use the task function approach combined with the application of the total rate of angular momentum to obtain a control law for the ankle. By this technique, the tracking becomes more smooth and the balance is assured. The control law proposed allows the upper part of the robot to be controlled independently since only the ankle actuators are concerned. We enounce the formal problem and present some simulations with real parameters of a 21 degrees of freedom biped robot.

  7. Protein folding guides disulfide bond formation

    OpenAIRE

    Qin, Meng; Wang, Wei; Thirumalai, D.

    2015-01-01

    Anfinsen inferred the principles of protein folding by studying a protein containing four disulfide bonds in the native state. However, how protein folding drives disulfide bond formation is poorly understood despite the role such proteins play in variety of extracellular and intracellular functions. We developed a method to mimic the complex chemistry of disulfide bond formation in molecular simulations, which is used to decipher the mechanism of folding of bovine pancreatic trypsin inhibito...

  8. A generalized exchange-correlation functional: the Neural-Networks approach

    CERN Document Server

    Zheng, X; Wang, X J; Chen, G H; Zheng, Xiao; Hu, LiHong; Wang, XiuJun; Chen, GuanHua

    2003-01-01

    A Neural-Networks-based approach is proposed to construct a new type of exchange-correlation functional for density functional theory. It is applied to improve B3LYP functional by taking into account of high-order contributions to the exchange-correlation functional. The improved B3LYP functional is based on a neural network whose structure and synaptic weights are determined from 116 known experimental atomization energies, ionization potentials, proton affinities or total atomic energies which were used by Becke in his pioneer work on the hybrid functionals [J. Chem. Phys. ${\\bf 98}$, 5648 (1993)]. It leads to better agreement between the first-principles calculation results and these 116 experimental data. The new B3LYP functional is further tested by applying it to calculate the ionization potentials of 24 molecules of the G2 test set. The 6-311+G(3{\\it df},2{\\it p}) basis set is employed in the calculation, and the resulting root-mean-square error is reduced to 2.2 kcal$\\cdot$mol$^{-1}$ in comparison to ...

  9. Jinzhai County Household Technical Change and Efficiency Change Analysis: Stochastic Frontier Production Function Approach

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Stochastic frontier production function approach is adopted, 93 farmer samples have been collected, pure efficiency, technical efficiency, technical change and scale efficiency and the institutional contribution have been calculated. The results indicated that increasing productivity is the sole measurement to reduce poverty, institution and technical change are the two key factors. Therefore, stable institution, improving technical changes are required. At present, it is urgent to make technical progre...

  10. An ab initio Non-Equilibrium Green Function Approach to Charge Transport: Dithiolethine

    Institute of Scientific and Technical Information of China (English)

    Alexander Schnurpfeil; SONG Bo; Martin Albrecht

    2006-01-01

    @@ We present a novel ab initio non-equilibrium approach to calculate the current across a molecular junction. The method rests on a wavefunction-based full ab initio description of the central region of the junction combined with a tight binding approximation for the electrodes in the frame of the Keldysh Green function formalism. Our procedure is demonstrated for a dithiolethine molecule located between silver electrodes. The main conducting channel is identified and the full current-voltage characteristic is calculated.

  11. Functional Integral Approach to the Transition Temperature of Attractive Interacting Bose Gas in Traps

    Institute of Scientific and Technical Information of China (English)

    HU Guang-Xi; DAI Xian-Xi

    2004-01-01

    The functional integral approach (FIA) is introduced to study the transition temperature of an imperfect Bose gas in traps.An interacting model in quantum statistical mechanics is presented.With the model we study a Bose gas with attractive interaction trapped in an external potential.We obtain the result that the transition temperature of a trapped Bose gas will slightly shift upwards owing to the attractive interacting force.Successful application of the FIA to Bose systems is demonstrated.

  12. MEASURING THE IMPACT OF FOOD SAFETY REGULATION-AN OUTPUT DIRECTIONAL DISTANCE FUNCTION APPROACH

    OpenAIRE

    Cho, Bo-Hyun; Hooker, Neal H.

    2004-01-01

    This paper provides a novel methodology to measure the impact of food safety regulation. An output directional distance function approach is applied to estimate the opportunity cost of food safety regulation. Such a measure should be included as part of the overall cost for a more precise benefit-cost analysis of food safety regulation. Using US Census and food safety recall data, the value of potential output loss due to food safety regulation is suggested $2.5 billion.

  13. Robust H∞ Control for Singular Time-Delay Systems via Parameterized Lyapunov Functional Approach

    Directory of Open Access Journals (Sweden)

    Li-li Liu

    2014-01-01

    Full Text Available A new version of delay-dependent bounded real lemma for singular systems with state delay is established by parameterized Lyapunov-Krasovskii functional approach. In order to avoid generating nonconvex problem formulations in control design, a strategy that introduces slack matrices and decouples the system matrices from the Lyapunov-Krasovskii parameter matrices is used. Examples are provided to demonstrate that the results in this paper are less conservative than the existing corresponding ones in the literature.

  14. Determinants of Profit Efficiency Among Small Scale Rice Farmers in Nigeria: A Profit Function Approach

    OpenAIRE

    Kolawole, Ogundari

    2006-01-01

    This study employs a stochastic frontier approach to examine profit efficiency of small scale rice farmers in Nigeria using farm-level survey data collected from 200 farmers in the study area. Data were analysed using descriptive statistics and standard profit function. The result shows that about 60 percent of potential profit is gain due to production efficiency while the remaining can be attributed to both technical and allocative inefficiencies in the study area. Also, the result further ...

  15. Improved radial basis function approach with the odd-even corrections

    CERN Document Server

    Niu, Z M; Liang, H Z; Niu, Y F; Guo, J Y

    2016-01-01

    The radial basis function (RBF) approach has been used to improve the mass predictions of nuclear models. However, systematic deviations exist between the improved masses and the experimental data for nuclei with different odd-even parities of ($Z$, $N$), i.e., the (even $Z$, even $N$), (even $Z$, odd $N$), (odd $Z$, even $N$), and (odd $Z$, odd $N$). By separately training the RBF for these four different groups, it is found that the systematic odd-even deviations can be cured in a large extend and the predictive power of nuclear mass models can thus be further improved. Moreover, this new approach can better reproduce the single-nucleon separation energies. Based on the latest version of Weizs\\"acker-Skyrme model WS4, the root-mean-square deviation of the improved masses with respect to known data falls to $135$ keV, approaching the chaos-related unpredictability limit ($\\sim 100$ keV).

  16. Hierarchical organization of functional connectivity in the mouse brain: a complex network approach

    Science.gov (United States)

    Bardella, Giampiero; Bifone, Angelo; Gabrielli, Andrea; Gozzi, Alessandro; Squartini, Tiziano

    2016-08-01

    This paper represents a contribution to the study of the brain functional connectivity from the perspective of complex networks theory. More specifically, we apply graph theoretical analyses to provide evidence of the modular structure of the mouse brain and to shed light on its hierarchical organization. We propose a novel percolation analysis and we apply our approach to the analysis of a resting-state functional MRI data set from 41 mice. This approach reveals a robust hierarchical structure of modules persistent across different subjects. Importantly, we test this approach against a statistical benchmark (or null model) which constrains only the distributions of empirical correlations. Our results unambiguously show that the hierarchical character of the mouse brain modular structure is not trivially encoded into this lower-order constraint. Finally, we investigate the modular structure of the mouse brain by computing the Minimal Spanning Forest, a technique that identifies subnetworks characterized by the strongest internal correlations. This approach represents a faster alternative to other community detection methods and provides a means to rank modules on the basis of the strength of their internal edges.

  17. Generalised analysis of the potential of an enterprise as a function of environmental parameters (theoretical approach

    Directory of Open Access Journals (Sweden)

    Karapeychik Igor M.

    2013-03-01

    Full Text Available Within the frameworks of the author’s concept of the potential of an enterprise as the ability to conduct its immanently appropriate activity and also the idea of presentation of the size of the potential in the form of potential function from parameters of the state of an enterprise and foreign economic environment the article develops a scientific and methodical approach to construction and analysis of the potential function of an enterprise. The offered approach envisages building an economic and mathematical model of an enterprise of the optimisation type with consideration of environmental factors, determination of the size of economic potential as a maximum possible (optimal with the set condition of an enterprise and external environment of net income, statistical test of the model with possible values of external parameters (formation of statistical sampling of the graph of the potential function of an enterprise and application of statistical methods including methods of correlation, factor and regression analysis, for the study of its properties. Operability of this approach is shown on the example of the study of properties of the potential function of a model enterprise. In the course of approbation the article demonstrates its ability to reveal specific features of impact of external factors on economic potential of an enterprise; establishes, as a common regularity, differential influence of various environmental factors, caused not only by the nature of these factors, but also production and economic specific features and specific state of an enterprise. The article shows that the quantitative values of the force of influence of the said factors upon the value of economic potential, obtained during statistical analysis of the potential function of an enterprise, could serve as an instrument of ranking these factors by the priority level in the goal setting tasks at the stage of formation of the strategy of enterprise development

  18. Green’s Function for Dirac Particle in a Non-Abelian Field: A Path Integral Approach

    OpenAIRE

    Boudieb, Sami; CHETOUANI, Lyazid

    2013-01-01

    The Green function for a Dirac particle moving in a non-Abelian field and having a particular form is exactly determined by the path integral approach. The wave functions were deduced from the residues of Green’s function. It is shown that the classical paths contributed mainly to the determination of the Green function.

  19. Hydrogen bonded supramolecular structures

    CERN Document Server

    Li, Zhanting

    2015-01-01

    This book covers the advances in the studies of hydrogen-bonding-driven supramolecular systems  made over the past decade. It is divided into four parts, with the first introducing the basics of hydrogen bonding and important hydrogen bonding patterns in solution as well as in the solid state. The second part covers molecular recognition and supramolecular structures driven by hydrogen bonding. The third part introduces the formation of hollow and giant macrocycles directed by hydrogen bonding, while the last part summarizes hydrogen bonded supramolecular polymers. This book is designed to b

  20. Silver- and gold-mediated nucleobase bonding.

    Science.gov (United States)

    Acioli, Paulo H; Srinivas, Sudha

    2014-08-01

    We report the results of a density functional theory investigation of the bonding of nucleobases mediated by silver and gold atoms in the gas phase. Our calculations use the Becke exchange and Perdew-Wang correlation functional (BPW91) combined with the Stuttgart effective core potentials to represent the valence electrons of gold, silver, and platinum, and the all-electron DGTZVP basis set for C, H, N, and O. This combination was chosen based on tests on the metal atoms and tautomers of adenine, cytosine, and guanine. To establish a benchmark to understand the metal-mediated bonding, we calculated the binding energy of each of the base pairs in their canonical forms. Our calculations show rather strong bonds between the Watson-Crick base pairs when compared with typical values for N-H-N and N-H-O hydrogen bonds. The neutral metal atoms tend to bond near the nitrogen atoms. The effect of the metal atoms on the bonding of nucleobases differs depending on whether or not the metal atoms bond to one of the hydrogen-bonding sites. When the silver or gold atoms bond to a non-hydrogen-bonding site, the effect is a slight enhancement of the cytosine-guanine bonding, but there is almost no effect on the adenine-thymine pairing. The metal atoms can block one of the hydrogen-bonding sites, thus preventing the normal cytosine-guanine and adenine-thymine pairings. We also find that both silver and gold can bond to consecutive guanines in a similar fashion to platinum, albeit with a significantly lower binding energy.