Chemical bond approach to metals and alloys
International Nuclear Information System (INIS)
The BCS theory of superconductivity was extended to the transition elements and their alloys by a chemical bond approach based on the electronic configurations of the Engel-- Brewer theory of alloys. The net attractive potential between electrons in Cooper pairs, V/sub BCS/, for the late transition series elements and alloys is shown to arise mainly from a generalized electron--electron interaction related to bonding of electrons on the d level alone, the phonon-induced attraction being nearly zero. A mechanism is proposed in which a scattering of superconducting d electrons into nonsuperconducting s and p states is responsible for a predictable reduction in V/sub BCS/. The electron-per-atom ratio and a new chemical parameter, the average atomic radius for coordination twelve, were applied successfully to the prediction of the maximum energy product of multiphase commercial permanent magnets. The correlations developed for the maximum energy product with these two parameters can be applied to optimize the compositions of existing permanent magnets or suggest hypothetical alloy mixtures of possibly better magnetic properties. Heats of reaction of the
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
A GENERAL APPROACH TO VALUING COMMODITY-LINKED BONDS
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) ...
Automating Partial Period Bond Valuation with Excel's Day Counting Functions
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…
BOND-ANGLE DISTRIBUTION FUNCTIONS IN METALLIC GLASSES
Hafner, J.
1985-01-01
Bond-angle distribution functions have been calculated for realistic models of metallic glasses. They suggest a defected icosahedral short-range bond-orientational order and a close analogy of the short-range topological order in the amorphous and in the crystalline states.
Multiple correlation function approach
Grebenkov, Denis S.
2016-01-01
The multiple correlation function approach is briefly presented and applied to investigate spin-echo signal attenuation due to restricted diffusion in simple geometries (slab, cylinder, and sphere) in the presence of surface relaxation. Exact and explicit representations for the zeroth and second moments of the total phase accumulated by diffusing spins are derived by using the Laplace transform summation technique. Within the Gaussian phrase approximation, these two moments determine the ...
Evaluating Callable and Putable Bonds: An Eigenfunction Expansion Approach
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...
Universal bond correlation function for two-dimensional polymer rings
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...
Integration a functional approach
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...
International Nuclear Information System (INIS)
Graphical abstract: Density functional calculations are frequently found to yield too long Eu-S bond distances. - Highlights: • Density functional theory provides too long Eu-S bond distances. • Ab initio structure optimizations needed to obtain reliable Eu-S bond distances. • Am-S bonds not necessarily more covalent than Eu-S bonds. - Abstract: In complexes of trivalent Eu and Am standard unrestricted Kohn–Sham density functional calculations tend to yield shorter bond distances for the Am-X than for the Eu-X bonds, especially when X is a so-called soft ligand. Since the ionic radius of AmIII is larger than the one of EuIII the reversed order of the bond distances is sometimes explained by a higher covalency of the Am-X bond compared to the one of the Eu-X bond. A comparison of density functional with wavefunction-based correlated calculations for several model systems reveals, however, that the energetically low-lying and spatially compact 4f shell of EuIII often is erroneously filled with significantly more than 6 electrons at the density functional theory level, thus yielding considerably too long bond distances. Particularly claims based on comparisons of structures optimized at the density functional level that the strong preference of the Cyanex 301 ligand for AmIII over EuIII is due to an increased covalency in the Am-S bonds should be viewed with some reservation
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.
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
Energy Technology Data Exchange (ETDEWEB)
Fifield, Leonard S.; Grate, Jay W.
2010-06-01
Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.
Site-selective and stereoselective functionalization of unactivated C-H bonds.
Liao, Kuangbiao; Negretti, Solymar; Musaev, Djamaladdin G; Bacsa, John; Davies, Huw M L
2016-05-12
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. PMID:27172046
Site-selective and stereoselective functionalization of unactivated C–H bonds
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.
Doster, Meghan E; Hatnean, Jillian A; Jeftic, Tamara; Modi, Sunjay; Johnson, Samuel A
2010-09-01
The ubiquitous Stille coupling reaction utilizes Sn-C bonds and is of great utility to organic chemists. Unlike the B-C bonds used in the Miyaura-Suzuki coupling reaction, which are readily obtained via direct borylation of C-H bonds, routes to organotin compounds via direct C-H bond functionalization are lacking. Here we report that the nickel-catalyzed reaction of fluorinated arenes and pyridines with vinyl stannanes does not provide the expected vinyl compounds via C-F activation but rather provides new Sn-C bonds via C-H functionalization with the loss of ethylene. This mechanism provides a new unanticipated methodology for the direct conversion of C-H bonds to carbon-heteroatom bonds. PMID:20690675
Metal nanoparticles functionalized with metal-ligand covalent bonds
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
"Pricing Convertible Bonds with Credit Risk: A Duffie-Singleton Approach "(in Japanese)
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.
Walton, Jay R.; Rivera-Rivera, Luis A.; Lucchese, Robert R.; Bevan, John W.
2016-05-01
A canonical approach is used to investigate prototypical multi-dimensional intermolecular interaction potentials characteristic of categories in van der Waals, hydrogen-bonded, and halogen-bonded intermolecular interactions. It is demonstrated that well-characterized potentials in Ar·HI, OC·HI, OC·HF, and OC·BrCl, can be canonically transformed to a common dimensionless potential with relative error less than 0.010. The results indicate common intrinsic bonding properties despite other varied characteristics in the systems investigated. The results of these studies are discussed in the context of the previous statement made by Slater (1972) concerning fundamental bonding properties in the categories of interatomic interactions analyzed.
Gradient Bundle Analysis: A Full Topological Approach to Chemical Bonding
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 ...
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.
A bond graph approach to modeling the anuran vocal production system.
Kime, Nicole M; Ryan, Michael J; Wilson, Preston S
2013-06-01
Air-driven vocal production systems such as those found in mammals, birds, and anurans (frogs and toads) combine pneumatic and mechanical elements in species-specific ways to produce a diversity of communication signals. This study uses bond graphs to model a generalized anuran vocal production system. Bond graphs allow an incremental approach to modeling dynamic physical systems involving different domains. Anurans provide an example of how signal diversity results from variation in the structure and behavior of vocal system elements. This paper first proposes a bond graph model of the integrated anuran vocal system as a framework for future study. It then presents a simulated submodel of the anuran sound source that produces sustained oscillations in vocal fold displacement and air flow through the larynx. The modeling approach illustrated here should prove of general applicability to other biological sound production systems, and will allow researchers to study the biomechanics of vocal production as well as the functional congruence and evolution of groups of traits within integrated vocal systems. PMID:23742365
The freeze-out bond exchange offer. An experimental approach
Flavio Bazzana; Luigi Mittone; Luciano Andreozzi
2012-01-01
A freeze-out bond exchange offer can occur when a firm wants to replace an exist- ing bond, issued with a covenant, with a new bond that does not have this type of restriction. If the bondholders are not fully coordinated, the shareholders can make the exchange offer unfair to capture wealth from the bondholders. We perform two experiments using the freeze-out game proposed by Oldfield (2004) to isolate (i) the level of information in the exchange offer and (ii) the role of the experience of ...
A non-perturbative approach to the random-bond Ising model
International Nuclear Information System (INIS)
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. (author). 30 refs, 1 fig
A Non-Perturbative Approach to the Random-Bond Ising Model
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.
Covalent bonding from alchemical linear response density functional theory
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...
Incorporation of in-plane interconnects to reflow bonding for electrical functionality
International Nuclear Information System (INIS)
Incorporation of in-plane electrical interconnects to reflow bonding is studied to provide electrical functionality to lab-on-a-chip or microfluidic devices. Reflow bonding is the packaging technology, in which glass tubes are joined to silicon substrates at elevated temperatures. The tubes are used to interface the silicon-based fluidic devices and are directly compatible with standard Swagelok® connectors. After the bonding, the electrically conductive lines will allow probing into the volume confined by the tube, where the fluidic device operates. Therefore methods for fabricating electrical interconnects that survive the bonding procedure at elevated temperature and do not alter the properties of the bond interface are investigated
Radiological emergency response - a functional approach
International Nuclear Information System (INIS)
The state of Louisiana's radiological emergency response programme is based on the federal guidance 'Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants' (NUREG-0654, FEMA-REP-1 Rev. 1). Over the past 14 years, the planning and implementation of response capabilities became more organized and efficient; the training programme has strengthened considerably; co-ordination with all participating agencies has assumed a more co-operative role, and as a result, a fairly well integrated response planning has evolved. Recently, a more 'functional' approach is being adopted to maximize the programme's efficiency not only for nuclear power plant emergency response, but radiological emergency response as a whole. First, several broad-based 'components' are identified; clusters of 'nodes' are generated for each component; these 'nodes' may be divided into 'sub-nodes' which will contain some 'attributes'; 'relational bonds' among the 'attributes' will exist. When executed, the process begins and continues with the 'nodes' assuming a functional and dynamic role based on the nature and characteristics of the 'attributes'. The typical response based on stand-alone elements is thus eliminated, the overlapping of functions is avoided, and a well structured and efficient organization is produced, that is essential for today's complex nature of emergency response. (author)
Sovereign bond yield spreads: A time-varying coefficient approach
Bernoth, Kerstin; Erdogan, Burcu
2010-01-01
We study the determinants of sovereign bond yield spreads across 10 EMU countries between Q1/1999 and Q1/2010. We apply a semiparametric time-varying coefficient model to identify, to what extent an observed change in the yield spread is due to a shift in macroeconomic fundamentals or due to altering risk pricing. We find that at the beginning of EMU, the government debt level and the general investors' risk aversion had a significant impact on interest differentials. In the subsequent years,...
Surface Reconstructions and Bonding via the Electron Localization Function: The Case of Si(001)
De Santis, L; Resta, R.
1999-01-01
The bonding pattern of a covalent semiconductor is disrupted when a surface is cut while keeping a rigid (truncated bulk) geometry. The covalent bonds are partly reformed (with a sizeable energy gain) when reconstruction is allowed. We show that the ``electron localization function'' (ELF)---applied within a first--principles pseudopotential framework---provides un unprecedented insight into the bonding mechanisms. In the unreconstructed surface one detects a partly metallic character, which ...
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
Block correlated second order perturbation theory with a generalized valence bond reference function
International Nuclear Information System (INIS)
The block correlated second-order perturbation theory with a generalized valence bond (GVB) reference (GVB-BCPT2) is proposed. In this approach, each geminal in the GVB reference is considered as a “multi-orbital” block (a subset of spin orbitals), and each occupied or virtual spin orbital is also taken as a single block. The zeroth-order Hamiltonian is set to be the summation of the individual Hamiltonians of all blocks (with explicit two-electron operators within each geminal) so that the GVB reference function and all excited configuration functions are its eigenfunctions. The GVB-BCPT2 energy can be directly obtained without iteration, just like the second order Møller–Plesset perturbation method (MP2), both of which are size consistent. We have applied this GVB-BCPT2 method to investigate the equilibrium distances and spectroscopic constants of 7 diatomic molecules, conformational energy differences of 8 small molecules, and bond-breaking potential energy profiles in 3 systems. GVB-BCPT2 is demonstrated to have noticeably better performance than MP2 for systems with significant multi-reference character, and provide reasonably accurate results for some systems with large active spaces, which are beyond the capability of all CASSCF-based methods
Haruspicy 3: The directed bond-animal generating function is not D-finite
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...
Evrensel, Ayşe Y.; Kutan, Ali M.
2004-01-01
This paper critically evaluates the existing empirical literature on creditor moral hazard in sovereign bond markets, proposes a unified theoretical approach to test for IMF-induced creditor moral hazard, and provides empirical evidence, using daily sovereign bond market spreads of Indonesia and Korea. The results suggest that IMF-related news regarding program negotiations and approval may be associated with creditor moral hazard, but their impact on spreads is short-lived, indicating that c...
Performance of a Nonempirical Density Functional on Molecules and Hydrogen-Bonded Complexes
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.
The pricing of the firm bond with extendable maturity by the structural form approach
REN Xuemin; GENG Lifang
2014-01-01
This article deals with the credit risk by the structural form approach.The firm has an option of extending maturity by the firm′s credit rating on the nominal expiry date .We obtain a pricing formula for the firm bond with extendable maturity the PDE approach and compare its return rate with that of the ordinary firm bond.The difficulty is to calculate the probability of default before the nominal expiry date and the conditional distribution of assets of the company under this condition.
The pricing of the firm bond with extendable maturity by the structural form approach
Directory of Open Access Journals (Sweden)
REN Xuemin
2014-02-01
Full Text Available This article deals with the credit risk by the structural form approach.The firm has an option of extending maturity by the firm′s credit rating on the nominal expiry date .We obtain a pricing formula for the firm bond with extendable maturity the PDE approach and compare its return rate with that of the ordinary firm bond.The difficulty is to calculate the probability of default before the nominal expiry date and the conditional distribution of assets of the company under this condition.
Approaches to Pendent Groups' Functionalization of Polyimide
Institute of Scientific and Technical Information of China (English)
无
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.
Symbolic Tensor Calculus -- Functional and Dynamic Approach
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.
Thanh Tung, Bui; Suzuki, Motohiro; Kato, Fumiki; Nemoto, Shunsuke; Watanabe, Naoki; Aoyagi, Masahiro
2013-04-01
High-precision integration has valuable meaning in heterogeneous convergent technology. In this paper we report on a new high-precision low-temperature bonding approach, capable of submicron alignment accuracy, based on the conventional ultrasonic flip-chip bonding technique and modified metal pad and bump elements. The interconnection pair made from a conductive-sloped hollow bonding pad (concave) and metal cone bump (convex) elements, i.e., misalignment self-correction elements, helps in aligning and maintaining the alignment between the chip and the substrate during stacking. By this method, the stacking accuracy can be improved significantly and effectively. Repeatable submicron (i.e., less than 500 nm) bonding accuracies are confirmed through experimental investigation. Moreover, reliable bond characteristics including electrical and mechanical properties are observed, validating the performance of the bonding approach. With these results, the proposed high-precision low-temperature bonding approach shows its suitability for heterogeneous electronics-optics integration applications.
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...
Green's function approach to the anisotropic Kondo-necklace lattice
International Nuclear Information System (INIS)
Full text: We have studied the effect of anisotropy on the quantum phase transition of the 2D anisotropic Kondo necklace lattice [1] within a Green's function approach [2]. In the disordered phase the ground state is the product of all singlet bonds between itinerant and localized spins. It is separated by a finite energy gap from the triplet excited states. The quantum phase transition to the antiferromagnetically ordered phase takes place where the gap vanishes. In this approach we use the bond operator formalism introduced in Ref.[3] where each bond is represented by the singlet and triplet operators. The Kondo necklace Hamiltonian in the bond operator representation is composed of the kinetic energy and pairing part (H2), the two particle interaction (H4) of the boson gas and a term which includes three boson operators (H3). In order to ensure that the physical states are either singlets or triplets we impose the hard-core condition by introducing an infinite on-site repulsion between triplet bosons (HU). The scattering vertex in the ladder approximation satisfies the Bethe-Salpeter equation [4]. By calculating the scattering vertex function we obtain the self energy contribution of the Hamiltonian HU. We have added the second order contribution of the self energy of H3 to the self energy of HU. It should be noted that the non conservation of triplet boson numbers requires the inclusion of the anomalous Green's functions. We treat H4 in mean-field theory, by splitting the quartic operator into all possible pairs. Finally we obtain the renormalization of coefficients in the H2 Hamiltonian and calculate the energy gap. Indeed at the critical point a condensation of triplet bosons occurs. We have numerically found the critical point of this model and compared our results with the corresponding mean field values [5]. Moreover, the critical exponent of the energy gap can be obtained more accurately than the mean field results. (authors)
Functionalization of Rhenium Aryl Bonds by O-Atom Transfer
Energy Technology Data Exchange (ETDEWEB)
Bischof, Steven M. [Scripps Research Inst., Jupiter, FL (United States); Cheng, Mu-Jeng [California Inst. of Technology (CalTech), Pasadena, CA (United States); Nielsen, Robert J. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Gunnoe, T. Brent [Univ. of Virginia, Charlottesville, VA (United States); Goddard, William A. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Periana, Roy A. [Scripps Research Inst., Jupiter, FL (United States)
2011-03-29
Aryltrioxorhenium (ArReO_{3}) has been demonstrated to show rapid oxy-functionalization upon reaction with O-atom donors, YO, to selectively generate the corresponding phenols in near quantitative yields. ^{18}O-Labeling experiments show that the oxygen in the products is exclusively from YO. DFT studies reveal a 10.7 kcal/mol barrier (Ar = Ph) for oxy-functionalization with H_{2}O_{2} via a Baeyer-Villiger type mechanism involving nucleophilic attack of the aryl group on an electrophilic oxygen of YO coordinated to rhenium.
The anchoring function: parental authority and the parent-child bond.
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
Spin-spin critical point correlation functions for the 2D random bond Ising and Potts models
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.
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
METAL NANOPARTICLES FUNCTIONALIZED WITH METAL-LIGAND COVALENT BONDS
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 ...
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.
New observations on hydrogen bonding in ice by density functional theory simulations
International Nuclear Information System (INIS)
In this paper, we report on a series of computational simulations on hydrogen bonding in two ice phases (Ih and Ic) using CASTEP with PW91 and RPBE exchange—correlation based on ab initio density functional theory. The strength of the H-bond is correlated with intramolecular O—H stretching, and the energy splitting exists for both the H-bond and covalent O—H stretching. By analyzing the dispersion relationship of ω(q), we observe the separation of the longitudinal optic (LO) mode from transverse optic (TO) mode at the gamma point, seemingly interpreting the controversial two H-bond peaks in the vibrational spectrum of ice recorded by inelastic incoherent neutron scattering experiments. The test of ambient environment on phonon density of sates (PDOS) shows that the relaxed tetrahedral structure is the most stable structural configuration for water clusters. (condensed matter: structural, mechanical, and thermal properties)
Aggregation functions: an approach using copulae
Marta Cardin; Maddalena Manzi
2007-01-01
In this paper we present the extension of the copula approach to aggregation functions. In fact we want to focus on a class of aggregation functions and present them in the multilinear form with marginal copulae. Moreover, we define the joint aggregation density function.
A Unified Bond Graph Modeling Approach for the Ejection Phase of the Cardiovascular System
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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.
Performance of a Nonempirical Density Functional on Molecules and Hydrogen-Bonded Complexes
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...
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.
Structure-directing factors when introducing hydrogen bond functionality to metal-organic frameworks
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, ...
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...
Metal-catalysed azidation of tertiary C-H bonds suitable for late-stage functionalization
Sharma, Ankit; Hartwig, John F.
2015-01-01
Many enzymes oxidize unactivated aliphatic C-H bonds selectively to form alcohols; however, biological systems do not possess enzymes that catalyse the analogous aminations of C-H bonds. The absence of such enzymes limits the discovery of potential medicinal candidates because nitrogen-containing groups are crucial to the biological activity of therapeutic agents and clinically useful natural products. In one prominent example illustrating the importance of incorporating nitrogen-based functionality, the conversion of the ketone of erythromycin to the -N(Me)CH2- group in azithromycin leads to a compound that can be dosed once daily with a shorter treatment time. For such reasons, synthetic chemists have sought catalysts that directly convert C-H bonds to C-N bonds. Most currently used catalysts for C-H bond amination are ill suited to the intermolecular functionalization of complex molecules because they require excess substrate or directing groups, harsh reaction conditions, weak or acidic C-H bonds, or reagents containing specialized groups on the nitrogen atom. Among C-H bond amination reactions, those forming a C-N bond at a tertiary alkyl group would be particularly valuable, because this linkage is difficult to form from ketones or alcohols that might be created in a biosynthetic pathway by oxidation. Here we report a mild, selective, iron-catalysed azidation of tertiary C-H bonds that occurs without excess of the valuable substrate. The reaction tolerates aqueous environments and is suitable for the functionalization of complex structures in the late stages of a multistep synthesis. Moreover, this azidation makes it possible to install a range of nitrogen-based functional groups, including those from Huisgen `click' cycloadditions and the Staudinger ligation. We anticipate that these reactions will create opportunities to modify natural products, their precursors and their derivatives to produce analogues that contain different polarity and charge as a
An iterative approach of protein function prediction
Directory of Open Access Journals (Sweden)
Chi Xiaoxiao
2011-11-01
Full Text Available Abstract Background Current approaches of predicting protein functions from a protein-protein interaction (PPI dataset are based on an assumption that the available functions of the proteins (a.k.a. annotated proteins will determine the functions of the proteins whose functions are unknown yet at the moment (a.k.a. un-annotated proteins. Therefore, the protein function prediction is a mono-directed and one-off procedure, i.e. from annotated proteins to un-annotated proteins. However, the interactions between proteins are mutual rather than static and mono-directed, although functions of some proteins are unknown for some reasons at present. That means when we use the similarity-based approach to predict functions of un-annotated proteins, the un-annotated proteins, once their functions are predicted, will affect the similarities between proteins, which in turn will affect the prediction results. In other words, the function prediction is a dynamic and mutual procedure. This dynamic feature of protein interactions, however, was not considered in the existing prediction algorithms. Results In this paper, we propose a new prediction approach that predicts protein functions iteratively. This iterative approach incorporates the dynamic and mutual features of PPI interactions, as well as the local and global semantic influence of protein functions, into the prediction. To guarantee predicting functions iteratively, we propose a new protein similarity from protein functions. We adapt new evaluation metrics to evaluate the prediction quality of our algorithm and other similar algorithms. Experiments on real PPI datasets were conducted to evaluate the effectiveness of the proposed approach in predicting unknown protein functions. Conclusions The iterative approach is more likely to reflect the real biological nature between proteins when predicting functions. A proper definition of protein similarity from protein functions is the key to predicting
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.
Ying, Fuming
2010-01-01
This thesis deals with two disjoint subdiciplines of quantum chemistry. One isthe most used electronic structure method today, density functional theory(DFT), and the other one of the least used electronic structure methods,valence bond theory (VB). The work on DFT is based on previous developments inthe department in density functional response theory and involves studies ofhyperfine coupling constants which are measured in electron paramagneticresonance experiments. The method employed i...
A Functional Approach to User Guides
DEFF Research Database (Denmark)
Nielsen, Sandro
2007-01-01
include all 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...... possible, user guides should contain text parts that have a directive discourse function, as this is an excellent way in which to tell the user how to benefit the most when consulting the dictionary in a function-specific context. The functional approach will enable lexicographers to write user guides that...
A Multivariate Approach to Functional Neuro Modeling
DEFF Research Database (Denmark)
Mørch, Niels J.S.
1998-01-01
This Ph.D. thesis, A Multivariate Approach to Functional Neuro Modeling, deals with the analysis and modeling of data from functional neuro imaging experiments. A multivariate dataset description is provided which facilitates efficient representation of typical datasets and, more importantly...... macroscopic variables to be manifestations of an underlying system. - A review of two microscopic basis selection procedures, namely principal component analysis and independent component analysis, with respect to their applicability to functional datasets. - Quantitative model performance assessment via a...
Density functional approaches to nuclear dynamics
Nakatsukasa, T.; Ebata, S; Avogadro, P.; Guo, L; Inakura, T.; Yoshida, K
2012-01-01
We present background concepts of the nuclear density functional theory (DFT) and applications of the time-dependent DFT with the Skyrme energy functional for nuclear response functions. Practical methods for numerical applications of the time-dependent Hartree-Fock-Bogoliubov theory (TDHFB) are proposed; finite amplitude method and canonical-basis TDHFB. These approaches are briefly reviewed and some numerical applications are shown to demonstrate their feasibility.
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.
Silver-catalyzed silicon-hydrogen bond functionalization by carbene insertion.
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
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.
Nahum, Tami Levy; Mamlok-Naaman, Rachel; Hofstein, Avi; Krajcik, Joseph
2007-01-01
The traditional pedagogical approach for teaching chemical bonding is often overly simplistic and not aligned with the most up-to-date scientific models. As a result, high-school students around the world lack fundamental understanding of chemical bonding. In order to improve students' understanding of this concept, it was essential to propose a…
Honacker, Christian; Qu, Zheng-Wang; Tannert, Jens; Layh, Marcus; Hepp, Alexander; Grimme, Stefan; Uhl, Werner
2016-04-14
Treatment of alkynyl-arylchlorogermanes ArylnGe(Cl)(C[triple bond, length as m-dash]C-(t)Bu)3-n (n = 1, 2) with HM(t)Bu2 (M = Al, Ga) yielded mixed Al or Ga alkenyl-alkynylchlorogermanes via hydrometallation reactions. Intramolecular interactions between the Lewis-basic Cl atoms and the Lewis-acidic Al or Ga atoms afforded MCGeCl heterocycles. The endocyclic M-Cl distances were significantly lengthened compared to the starting compounds and indicated Ge-Cl bond activation. Dual hydrometallation succeeded only with HGa(t)Bu2. One Ga atom of the product was involved in a Ga-Cl bond, while the second one had an interaction to a C-H bond of a phenyl group. In two cases treatment of chlorogermanes with two equivalents of HAl(t)Bu2 resulted in hydroalumination of one alkynyl group and formation of unprecedented Ge-H functionalized germanes, Aryl-Ge(H)(C[triple bond, length as m-dash]C-(t)Bu)[C(Al(t)Bu2)[double bond, length as m-dash]C(H)-(t)Bu] (Aryl = mesityl, triisopropylphenyl). The Al atoms of these compounds interacted with the α-C atoms of the alkynyl groups. Ph(Cl)Ge(C[triple bond, length as m-dash]C-(t)Bu)[C(Al(t)Bu2}[double bond, length as m-dash]C(H)-(t)Bu] reacted in an unusual Cl/(t)Bu exchange to yield the tert-butylgermane Ph((t)Bu)Ge(C[triple bond, length as m-dash]C-(t)Bu)[C{Al((t)Bu)(Cl)}[double bond, length as m-dash]C(H)-(t)Bu]. Quantum chemical calculations suggested the formation of a germyl cation as a transient intermediate. PMID:26610394
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
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.
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.
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.
[Partial lease squares approach to functional analysis].
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
Optogenetic approaches for functional mouse brain mapping
Diana H Lim; LeDue, Jeffrey; Mohajerani, Majid H.; Vanni, Matthieu P.; Murphy, Timothy H.
2013-01-01
To better understand the connectivity of the brain, it is important to map both structural and functional connections between neurons and cortical regions. In recent years, a set of optogenetic tools have been developed that permit selective manipulation and investigation of neural systems. These tools have enabled the mapping of functional connections between stimulated cortical targets and other brain regions. Advantages of the approach include the ability to arbitrarily stimulate brain reg...
Chemical bond fundamental aspects of chemical bonding
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
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...
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...
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
Functionalization and bioimmobilization of silicon surfaces with Si–N bonded monolayer
International Nuclear Information System (INIS)
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, C2H4 (NH2)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
Würthner, Frank; Yao, Sheng
2003-11-14
The condensation of the CH acidic heterocycles 4-alkyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (5a and b) and barbituric acid (15) with electron-rich thiophene aldehydes and benzaldehyde derivatives affords the respective monomethine dyes 10-13 and 17-19. The formylation of 5a,b and 15 with N,N'-diphenylformamidine or dibutylformamide in acetic anhydride and further reaction with 4-picolinium salts 9a,b provide the dimethine dyes 14 and 20a,b. Triple hydrogen bonding of the imide groups of merocyanine dyes 10-14 has been investigated by NMR titration experiments with melamine 21. Despite rather pronounced variations of the charge-transfer properties within the given series of dyes, minor changes of their binding constants have been observed. These results could be rationalized by semiempirical calculations that reveal small changes in the charge density at the oxygen functionalities involved in hydrogen bonding upon variation of the electron-donating carbocyclic or heterocyclic groups at the terminal double bond. Although the binding constants for triple hydrogen bonding between imides and melamines are rather weak in chloroform, they proved to be strong enough to facilitate dissolution of some of these dyes in aliphatic solvents by coordination to amphiphilic melamines and dipolar aggregation. UV-vis spectral changes observed in methylcyclohexane vs chloroform suggest the formation of colloidal assemblies through noncovalent polymerization. PMID:14604366
Introducing linear functions: an alternative statistical approach
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.
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
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).
A functional approach for managing ITER operations
International Nuclear Information System (INIS)
Highlights: ► A function-oriented approach for defining and organizing all the functions required to perform the mission has been developed. ► A Functional Breakdown Structure providing a complete hierarchy of functions on multiple levels is presented. ► The FBS is used for giving a good visibility of ITER project needs and requirements. ► Reliability (R) and Inherent Availability (AI) of basic functions are calculated from data on the structures, systems and components (failure rate and time to repair) for obtaining the Availability objectives of the ITER project. - Abstract: ITER is currently the most ambitious project on nuclear fusion research. Its objective is to demonstrate the feasibility of fusion as an energy source for the future. The complexity of the systems required to meet this challenge present many opportunities for omissions or incorrect assumptions. System engineering allows the engineer to deal with such a complexity by developing a Functional Breakdown Structure (FBS). Unlike a Plant Breakdown Structure (PBS), the FBS is a function-oriented tree, not a product-oriented tree. It details operations or activities that have to be performed as needed functions of the architecture, allowing identification of any missing elements, defining the personnel skills required to operate the architecture and managing the machine availability.
Role of functional groups in surface bonding of planar π-conjugated molecules
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.
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
C-F sp(2) bond functionalization mediated by niobium complexes.
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
Estimating Function Approaches for Spatial Point Processes
Deng, Chong
Spatial point pattern data consist of locations of events that are often of interest in biological and ecological studies. Such data are commonly viewed as a realization from a stochastic process called spatial point process. To fit a parametric spatial point process model to such data, likelihood-based methods have been widely studied. However, while maximum likelihood estimation is often too computationally intensive for Cox and cluster processes, pairwise likelihood methods such as composite likelihood, Palm likelihood usually suffer from the loss of information due to the ignorance of correlation among pairs. For many types of correlated data other than spatial point processes, when likelihood-based approaches are not desirable, estimating functions have been widely used for model fitting. In this dissertation, we explore the estimating function approaches for fitting spatial point process models. These approaches, which are based on the asymptotic optimal estimating function theories, can be used to incorporate the correlation among data and yield more efficient estimators. We conducted a series of studies to demonstrate that these estmating function approaches are good alternatives to balance the trade-off between computation complexity and estimating efficiency. First, we propose a new estimating procedure that improves the efficiency of pairwise composite likelihood method in estimating clustering parameters. Our approach combines estimating functions derived from pairwise composite likeli-hood estimation and estimating functions that account for correlations among the pairwise contributions. Our method can be used to fit a variety of parametric spatial point process models and can yield more efficient estimators for the clustering parameters than pairwise composite likelihood estimation. We demonstrate its efficacy through a simulation study and an application to the longleaf pine data. Second, we further explore the quasi-likelihood approach on fitting
A Transtextual Approach to Lexicographic Functions
Directory of Open Access Journals (Sweden)
Rufus H. Gouws
2011-10-01
Full Text Available
Abstract: The development of theoretical lexicography clearly indicates a movement towards a more general recognition of the role of lexicographic functions. A consistent application of lexicographic functions has a major influence on the contents of dictionary articles but also on the data distribution and even the typological classification. In the discussion of lexicographic functions, the emphasis has primarily been on the central list of dictionaries. This article proposes an approach where outer texts are also selected and compiled in order to make an active contribution to achieving the lexicographic functions of a given dictionary. A distinction is made between function-adhering and non-function-adhering outer texts. The function-adhering outer texts can further be divided into integrated and non-integrated function-adhering outer texts. With reference to the data distribution programme of a dictionary, it is suggested that in the planning of every dictionary, provision should be made for a function allocation programme. This will ensure that the identified functions of a given dictionary will be realised in both the central list and the outer texts.
Keywords: BACK MATTER TEXTS, CENTRAL LIST, COGNITIVE FUNCTION, DATA DISTRIBUTION, FRAME STRUCTURE, FRONT MATTER TEXTS, FUNCTION ALLOCATION PROGRAMME, FUNCTION-ADHERING OUTER TEXTS, FUNCTIONAL TEXT PARTS, INTEGRATED FUNCTION-ADHERING OUTER TEXTS, LEXICOGRAPHIC FUNCTIONS, NON-FUNCTION-ADHERING OUTER TEXTS, NON-INTEGRATED FUNCTION-ADHERING OUTER TEXTS, OUTER TEXTS, TEXT PRODUCTION, TEXT RECEPTION, TRANSTEXTUAL APPROACH
Opsomming: 'n Transtekstuele benadering tot leksikografiese funksies. Die ontwikkeling van die teoretiese leksikografie toon 'n duidelike beweging in die rigting van 'n groter erkenning aan die rol van leksikografiese funksies. 'n Konsekwente toepassing van leksiko-grafiese funksies het 'n ingrypende invloed op die inhoud van woordeboekartikels maar ook op die
Partition functions and graphs: A combinatorial approach
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...
Density Functional Calculations of C-NO2 Bond Dissociation Energies for Nitroalkanes Molecules
Institute of Scientific and Technical Information of China (English)
无
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.
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.
International Nuclear Information System (INIS)
The definition of a hydrogen bond (H-bond) is intimately related to the topological and dynamic properties of the hydrogen bond network within liquid water. The development of a universal H-bond definition for water is an active area of research as it would remove many ambiguities in the network properties that derive from the fixed definition employed to assign whether a water dimer is hydrogen bonded. This work investigates the impact that an electronic-structure based definition, an energetic, and a geometric definition of the H-bond has upon both topological and dynamic network behavior of simulated water. In each definition, the use of a cutoff (either geometric or energetic) to assign the presence of a H-bond leads to the formation of transiently bonded or broken dimers, which have been quantified within the simulation data. The relative concentration of transient species, and their duration, results in two of the three definitions sharing similarities in either topological or dynamic features (H-bond distribution, H-bond lifetime, etc.), however no two definitions exhibit similar behavior for both classes of network properties. In fact, two networks with similar local network topology (as indicated by similar average H-bonds) can have dramatically different global network topology (as indicated by the defect state distributions) and altered H-bond lifetimes. A dynamics based correction scheme is then used to remove artificially transient H-bonds and to repair artificially broken bonds within the network such that the corrected network exhibits the same structural and dynamic properties for two H-bond definitions (the properties of the third definition being significantly improved). The algorithm described represents a significant step forward in the development of a unified hydrogen bond network whose properties are independent of the original hydrogen bond definition that is employed
An approach to real-time process control of semiconductor wire-bonding
1972-01-01
Thermal probe using infrared-transparent optical fiber attached to tip of collet with resin to prevent movement during bonding is used to accurately measure temperature during wire bonding on semiconductors for use in large scale integrated circuits.
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.
Lee, Alex; Kim, Minjung; Chelikowsky, James
2015-03-01
Recent experimental noncontact atomic force microscopy (AFM) studies on 8-hydroxyquinoline (8-hq) assemblies have imaged distinct lines between molecules that are thought to represent intermolecular bonding. To aid the interpretation of these images, we calculate simulated AFM images of an 8-hq dimer with a CO functionalized tip using a real-space pseudopotential formalism. We examine the effects of Pauli repulsion and tip probe relaxation as explanations for the enhanced resolution that resolves these intermolecular force lines. Our study aims to compute ab initio real-space images of intermolecular interactions.
Katranchev, B.; Petrov, M.; Keskinova, E.; Naradikian, H.; Rafailov, P. M.; Dettlaff-Weglikowska, U.; Spassov, T.
2014-12-01
The liquid crystalline (LC) nature of alkyloxybenzoic acids is preserved after adding of any mesogenic or non-mesogenic compound through hydrogen bonding. However, this noncovalent interaction provokes a sizable effect on the physical properties as, e. g. melting point and mesomorphic states. In the present work we investigate nanocomposites, prepared by mixture of the eighth homologue of p-n-alkyloxybenzoic acids (8OBA) with single-walled carbon nanotubes (SWCNT) with the purpose to modify the optical properties of the liquid crystal. We exercise optical control on the LC system by inserting SWCNT specially functionalized by carboxylic groups. Since the liquid crystalline state combines order and mobility at the molecular (nanoscale) level, molecular modification can lead to different macroscopical nanocomposite symmetry. The thermal properties of the functionalized nanocomposite are confirmed by DSC analyses. The mechanism of the interaction between surface-treated nanoparticles (functionalized nanotubes) and the liquid crystal 8OBA bent- dimer molecules is briefly discussed.
International Nuclear Information System (INIS)
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 thionyl chloride to give acyl chloride bound GOS. Gold nanoparticles (AuNPs) were functionalized using 4-aminothiophenol in a single-phase system to introduce amino groups on their surface through the well-developed Au-S chemistry. Subsequently, amino groups of AuNPs were reacted with acyl chloride groups of GOS to form a novel hybrid material containing GOS and AuNPs. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy were used to study the changes in surface functionalities and demonstrate the successful immobilization of AuNPs on GOS surface. High resolution transmission electron microscopy (HR-TEM), field emission scanning electronic microscopy (FE-SEM), and atomic force microscopy (AFM) were employed to investigate the morphologies of prepared AuNPs and their distribution onto the GOS surface. Thermogravimetric analysis (TGA) was used to characterize the thermal stability of the samples on heating.
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...
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.
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...
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...
Meyer, E.
1992-01-01
Conserved structural patterns of internal water molecules and/or H-bond chains were observed and are here correlated in this review, which then describes two functional properties: equilibration of hydrostatic pressure and proton transport. Available evidence in support of these hypotheses is presented, together with suggested experiments to test them. High-resolution crystal structures of a variety of proteins were studied with interactive computer graphics. Conserved H-bonding linkages may ...
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.)
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.
The Bond Order of C2 from a Strictly N-Representable Natural Orbital Energy Functional Perspective.
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
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.
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 of low-lying isomers and van der Waals (vdW) dispersion forces to give key contributions to the dissociation energy. The question raised whether functionals that incorporate vdW forces implicitly int...
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 one intermolecular H-bond showed a high density of thermal storage up to 269.8 kJ kg(-1) compared with RGO-ortho-AZO (149.6 kJ kg(-1)) with multiple intra- and intermolecular H-bonds of AZO according to relaxed stable structures. Thermal storage in experiment was the same order magnitude to theoretical data based on ΔH calculated by density functional theory and packing density. Photoactive RGO-AZO hybrid can be developed for high-performance solar thermal storage by optimizing molecular H-bonds. PMID:24247355
Martínez-Periñán, Emiliano; de Juan, Alberto; Pouillon, Yann; Schierl, Christoph; Strauss, Volker; Martín, Nazario; Rubio, Ángel; Guldi, Dirk M.; Lorenzo, Encarnación; Pérez, Emilio M.
2016-04-01
We describe the functionalization of SWNTs enriched in (6,5) chirality with electron donating macrocycles to yield rotaxane-type mechanically interlocked carbon nanotubes (MINTs). Investigations by means of electron microscopy and control experiments corroborated the interlocked nature of the MINTs. A comprehensive characterization of the MINTs through UV-vis-NIR, Raman, fluorescence, transient absorption spectroscopy, cyclic voltammetry, and chronoamperometry was carried out. Analyses of the spectroscopic data reveal that the MINT-forming reaction proceeds with diameter selectivity, favoring functionalization of (6,5) SWNTs rather than larger (7,6) SWNTs. In the ground state, we found a lack of significant charge-transfer interactions between the electron donor exTTF and the SWNTs. Upon photoexcitation, efficient charge-transfer between the electron donating exTTF macrocycles and SWNTs was demonstrated. As a complement, we established significantly different charge-transfer rate constants and diffusion coefficients for MINTs and the supramolecular models, which confirms the fundamentally different type of interactions between exTTF and SWNTs in the presence or absence of the mechanical bond. Molecular mechanics and DFT calculations support the experimental findings.We describe the functionalization of SWNTs enriched in (6,5) chirality with electron donating macrocycles to yield rotaxane-type mechanically interlocked carbon nanotubes (MINTs). Investigations by means of electron microscopy and control experiments corroborated the interlocked nature of the MINTs. A comprehensive characterization of the MINTs through UV-vis-NIR, Raman, fluorescence, transient absorption spectroscopy, cyclic voltammetry, and chronoamperometry was carried out. Analyses of the spectroscopic data reveal that the MINT-forming reaction proceeds with diameter selectivity, favoring functionalization of (6,5) SWNTs rather than larger (7,6) SWNTs. In the ground state, we found a lack of
Wafer-level packaging and laser bonding as an approach for silicon-into-lab-on-chip integration
International Nuclear Information System (INIS)
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. (paper)
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
Deiner, L Jay; Farjami, Elaheh
2015-01-01
In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated
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.
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.
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.
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.)
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...... presented in this manuscript focuses on studying bond pad corrosion by selecting an appropriate model system and a dedicated set of electrochemical and analytical experimental tools. Taking into account the complex three-dimensional structure and the small dimensions of Au-Al interconnections (around 50......-focused ion beam and Auger electron spectroscopy. The results revealed that the electrochemical behaviour of thin gold films was influenced by the underlying metal layers and the microstructural changes during heat treatment. The effect of the underlying layers on the electrochemical properties of the top...
A multiscale approach to model hydrogen bonding: The case of polyamide
Energy Technology Data Exchange (ETDEWEB)
Gowers, Richard J., E-mail: richard.gowers@manchester.ac.uk; Carbone, Paola, E-mail: paola.carbone@manchester.ac.uk [School of Chemical Engineering and Analytical Science, University of Manchester, Manchester M13 9PL (United Kingdom)
2015-06-14
We present a simple multiscale model for polymer chains in which it is possible to selectively remove degrees of freedom. The model integrates all-atom and coarse-grained potentials in a simple and systematic way and allows a fast sampling of the complex conformational energy surface typical of polymers whilst maintaining a realistic description of selected atomistic interactions. In particular, we show that it is possible to simultaneously reproduce the structure of highly directional non-bonded interactions such as hydrogen bonds and efficiently explore the large number of conformations accessible to the polymer chain. We apply the method to a melt of polyamide removing from the model only the degrees of freedom associated to the aliphatic segments and keeping at atomistic resolution the amide groups involved in the formation of the hydrogen bonds. The results show that the multiscale model produces structural properties that are comparable with the fully atomistic model despite being five times faster to simulate.
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.
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.
International Nuclear Information System (INIS)
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
Directory of Open Access Journals (Sweden)
Michael Ghobrial
2014-09-01
Full Text Available The synthesis of 1,2,3-trisubstituted indoles was investigated. More specifically, straightforward synthetic routes towards 1-(1,2-diarylindol-3-yl-N-PG-THIQs (PG = protecting group, THIQ = tetrahydroisoquinoline employing transition metal-catalyzed C–H and N–H-bond functionalization were explored. It was found that the synthesis of the target compounds is strongly dependent on the order of events. Hence, depending on the requirements of a synthetic problem the most suitable and promising pathway can be chosen. Additionally, a new synthetic approach towards 1,2-diarylindoles starting from 1-arylindole could be established in the course of our investigation by using a palladium-catalyzed protocol. Such 1,2-diarylindoles were successfully reacted with N-Boc-THIQ to furnish 1,2,3-trisubstituted indoles as target compounds. Furthermore, regioselective N-arylation of protected and unprotected 1-(indol-3-yl-THIQs was successfully conducted using either simple iron or copper salts as catalysts.
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.
Infrared study of the hydrogen bonding site in a poly-functional schiff base: N( sp2) or N( sp)?
Laureys, C.; Zeegers-Huyskens, Th.
1987-05-01
The hydrogen bond complexes between phenol derivatives and the Schiff base [(diphenylmethylene)amino]-acetonitrile have been studied by infrared spectroscopy in carbon tetrachloride solution. The thermodynamic data and the infrared spectra investigated in the ν OH, ν CN and ν CN region indicate that complex formation occurs at the nitrogen atom of the nitrile function. The hydrogen bonding site is in this case governed by the accessibility of the lone pair which is markedly higher for the N( sp) than the N( sp2) electrons.
A Transtextual Approach to Lexicographic Functions
Rufus H Gouws
2011-01-01
Abstract: The development of theoretical lexicography clearly indicates a movement towards a more general recognition of the role of lexicographic functions. A consistent application of lexicographic functions has a major influence on the contents of dictionary articles but also on the data distribution and even the typological classification. In the discussion of lexicographic functions, the emphasis has primarily been on the central list of dictionaries. This article proposes an ap...
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
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.
A theoretical perspective of the nature of hydrogen-bond types - the atoms in molecules approach
Czech Academy of Sciences Publication Activity Database
Pandiyan, B. V.; Kolandaivel, P.; Deepa, Palanisamy
2014-01-01
Roč. 112, č. 12 (2014), s. 1609-1623. ISSN 0026-8976 Institutional support: RVO:61388963 Keywords : hydrogen bond * proton affinity * deprotanation enthalpy * atoms in molecules * chemical shift Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.720, year: 2014
A Functional Analytic Approach to Group Psychotherapy
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…
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.
Ben Doudou, Bessem; Chen, Jun; Vivet, Alexandre; Poilâne, Christophe
2016-03-01
In this paper, we have investigated the chemical bond interactions between covalently functionalized zigzag (5,0) and (8,0) SWCNT-SWCNT via various covalent linkages. Side-to-side junctions connected via amide, ester and anhydride linkages were particularly studied. The geometries and energy of the forming reaction were investigated using first-principles density functional theory. Furthermore, the band structures and the total density of states (DOS) of the junctions have also been analyzed. Our results show that several promising structures could be obtained by using chemical connection strategy and particularly the junctions formed by coupling amino functionalized SWCNT and carboxylic acid functionalized SWCNT was more favorable.
DEFF Research Database (Denmark)
Kepp, Kasper Planeta
2009-01-01
This paper presents systematic data for 200 neutral diatomic molecules ML (M is it second- or third-row d-block metal and L = H, F, Cl, Br, I, C, N, O, S, or Se) Computed with the density functionals TPSSh and BP86. With experimental Structures and bond enthalpies available for many of these...... molecules, the computations first document the high accuracy of TPSSh, giving metal-ligand bond lengths with a mean absolute error of similar to 0.01 angstrom for the second row and 0.03 angstrom for the third row. TPSSh provides metal-ligand bond enthalpies with mean absolute errors of 37 and 44 kJ/mol for......, characteristic 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...
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
Translation: Towards a Critical-Functional Approach
Sadeghi, Sima; Ketabi, Saeed
2010-01-01
The controversy over the place of translation in the teaching of English as a Foreign Language (EFL) is a thriving field of inquiry. Many older language teaching methodologies such as the Direct Method, the Audio-lingual Method, and Natural and Communicative Approaches, tended to either neglect the role of translation, or prohibit it entirely as a…
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
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
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.
Genomic and functional approaches to genetic adaptation
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...
Exponential function approach to parabolic equations
Lin, Chin-Yuan
2014-01-01
This volume is on initial-boundary value problems for parabolic partial differential equations of second order. It rewrites the problems as abstract Cauchy problems or evolution equations, and then solves them by the technique of elementary difference equations. Because of this, the volume assumes less background and provides an easy approach for readers to understand. Contents:Existence Theorems for Cauchy ProblemsExistence Theorems for Evolution Equations (I)Linear Autonomous Parabolic EquationsNonlinear Autonomous Parabolic EquationsLinea
Energy Density Functional Approach to Superfluid Nuclei
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.
Density Functional Theory Approach to Nuclear Fission
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.
Energy Technology Data Exchange (ETDEWEB)
Horowitz, Scott; Dirk, Lynnette M.A.; Yesselman, Joseph D.; Nimtz, Jennifer S.; Adhikari, Upendra; Mehl, Ryan A.; Scheiner, Steve; Houtz, Robert L.; Al-Hashimi, Hashim M.; Trievel, Raymond C. [Oregon State U.; (Michigan); (Utah SU); (HHMI); (Kentucky)
2013-09-06
S-Adenosylmethionine (AdoMet)-based methylation is integral to metabolism and signaling. AdoMet-dependent methyltransferases belong to multiple distinct classes and share a catalytic mechanism that arose through convergent evolution; however, fundamental determinants underlying this shared methyl transfer mechanism remain undefined. A survey of high-resolution crystal structures reveals that unconventional carbon–oxygen (CH···O) hydrogen bonds coordinate the AdoMet methyl group in different methyltransferases irrespective of their class, active site structure, or cofactor binding conformation. Corroborating these observations, quantum chemistry calculations demonstrate that these charged interactions formed by the AdoMet sulfonium cation are stronger than typical CH···O hydrogen bonds. Biochemical and structural studies using a model lysine methyltransferase and an active site mutant that abolishes CH···O hydrogen bonding to AdoMet illustrate that these interactions are important for high-affinity AdoMet binding and transition-state stabilization. Further, crystallographic and NMR dynamics experiments of the wild-type enzyme demonstrate that the CH···O hydrogen bonds constrain the motion of the AdoMet methyl group, potentially facilitating its alignment during catalysis. Collectively, the experimental findings with the model methyltransferase and structural survey imply that methyl CH···O hydrogen bonding represents a convergent evolutionary feature of AdoMet-dependent methyltransferases, mediating a universal mechanism for methyl transfer.
Quantum Confinement in Hydrogen Bond
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.
Functional renormalisation approach to driven dissipative dynamics
Mathey, Steven
2014-01-01
We investigate stationary scaling states of Burgers' and Gross-Pitaevskii equations (GPE). The path integral representation of the steady state of the stochastic Burgers equation is used in order to investigate the scaling solutions of the system at renormalisation group (RG) fixed points. We employ the functional RG in order to access the non-perturbative regime. We devise an approximation that respects Galilei invariance and is designed to resolve the frequency and momentum dependence of low order correlation functions. We establish a set of RG fixed point equations for inverse propagators with an arbitrary frequency and momentum dependence. In all spatial dimensions they yield a continuum of fixed points as well as an isolated one. These results are fully compatible with the existing literature for $d=1$. For $d\
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.
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.
International Nuclear Information System (INIS)
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
Nishiyama, Yoshihiro
2005-01-01
A transfer-matrix simulation scheme for the three-dimensional (d=3) bond percolation is presented. Our scheme is based on Novotny's transfer-matrix formalism, which enables us to consider arbitrary (integral) number of sites N constituting a unit of the transfer-matrix slice even for d=3. Such an arbitrariness allows us to perform systematic finite-size-scaling analysis of the criticality at the percolation threshold. Diagonalizing the transfer matrix for N =4,5,...,10, we obtain an estimate ...
Nishiyama, Yoshihiro
2006-01-01
A transfer-matrix simulation scheme for the three-dimensional (d=3) bond percolation is presented. Our scheme is based on Novotny’s transfer-matrix formalism, which enables us to consider arbitrary (integral) number of sites N constituting a unit of the transfer-matrix slice even for d=3 . Such an arbitrariness allows us to perform systematic finite-size-scaling analysis of the criticality at the percolation threshold. Diagonalizing the transfer matrix for N=4,5,…,10 , we obtain an estimate for the correlation-length critical exponent ν=0.81(5) .
Dentin Bonding Testing Using a Mini-interfacial Fracture Toughness Approach.
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
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.
An extrinsic function-level evolvable hardware approach
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...
Functional genomics approach to hypoxia signaling.
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
Lyapunov Functions Family Approach to Transient Stability Assessment
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...
A new approach to bootstrap inference in functional coefficient models
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...
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.
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
Czech Academy of Sciences Publication Activity Database
Ulrich, C. M.; Hashibon, A.; Svoboda, Jiří; Elsässer, C.; Helm, D.; Riedel, H.
2011-01-01
Roč. 59, č. 20 (2011), s. 7634-7644. ISSN 1359-6454 R&D Projects: GA ČR GAP204/10/1784 Institutional research plan: CEZ:AV0Z20410507 Keywords : Bonding * Diffusion * Intermetallic compounds Subject RIV: BJ - Thermodynamics Impact factor: 3.755, year: 2011
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.
Green functions of graphene: An analytic approach
International Nuclear Information System (INIS)
In this article we derive the lattice Green Functions (GFs) of graphene using a Tight Binding Hamiltonian incorporating both first and second nearest neighbour hoppings and allowing for a non-orthogonal electron wavefunction overlap. It is shown how the resulting GFs can be simplified from a double to a single integral form to aid computation, and that when considering off-diagonal GFs in the high symmetry directions of the lattice this single integral can be approximated very accurately by an algebraic expression. By comparing our results to the conventional first nearest neighbour model commonly found in the literature, it is apparent that the extended model leads to a sizeable change in the electronic structure away from the linear regime. As such, this article serves as a blueprint for researchers who wish to examine quantities where these considerations are important
Green functions of graphene: An analytic approach
Energy Technology Data Exchange (ETDEWEB)
Lawlor, James A., E-mail: jalawlor@tcd.ie [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Ferreira, Mauro S. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); CRANN, Trinity College Dublin, Dublin 2 (Ireland)
2015-04-15
In this article we derive the lattice Green Functions (GFs) of graphene using a Tight Binding Hamiltonian incorporating both first and second nearest neighbour hoppings and allowing for a non-orthogonal electron wavefunction overlap. It is shown how the resulting GFs can be simplified from a double to a single integral form to aid computation, and that when considering off-diagonal GFs in the high symmetry directions of the lattice this single integral can be approximated very accurately by an algebraic expression. By comparing our results to the conventional first nearest neighbour model commonly found in the literature, it is apparent that the extended model leads to a sizeable change in the electronic structure away from the linear regime. As such, this article serves as a blueprint for researchers who wish to examine quantities where these considerations are important.
Bond order potentials for fracture, wear, and plasticity
Pastewka, L.; Mrovec, M.; Moseler, M.; Gumbsch, P.
2012-01-01
Coulson's bond order is a chemically intuitive quantity that measures the difference in the occupation of bonding and anti-bonding orbitals. Both empirical and rigorously derived bond order expressions have evolved in the course of time and proven very useful for atomistic modeling of materials. The latest generation of empirical formulations has recently been augmented by screening-function approaches. Using friction and wear of diamond and diamond-like carbon as examples, we demonstrate tha...
International Nuclear Information System (INIS)
The solvent-dependent luminescent metal-organic framework (MOF), Cu2(L)2·CH2Cl2 (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 S1 of Cu2(L)2·CH2Cl2. 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 S1 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). ► 1H NMR and binding energies indicate H-bond weakening in excited states. ► The coordination bonds become stronger in the excited states
Toward Intelligent Hemodynamic Monitoring: A Functional Approach
Directory of Open Access Journals (Sweden)
Pierre Squara
2012-01-01
Full Text Available Technology is now available to allow a complete haemodynamic analysis; however this is only used in a small proportion of patients and seems to occur when the medical staff have the time and inclination. As a result of this, significant delays occur between an event, its diagnosis and therefore, any treatment required. We can speculate that we should be able to collect enough real time information to make a complete, real time, haemodynamic diagnosis in all critically ill patients. This article advocates for “intelligent haemodynamic monitoring”. Following the steps of a functional analysis, we answered six basic questions. (1 What is the actual best theoretical model for describing haemodynamic disorders? (2 What are the needed and necessary input/output data for describing this model? (3 What are the specific quality criteria and tolerances for collecting each input variable? (4 Based on these criteria, what are the validated available technologies for monitoring each input variable, continuously, real time, and if possible non-invasively? (5 How can we integrate all the needed reliably monitored input variables into the same system for continuously describing the global haemodynamic model? (6 Is it possible to implement this global model into intelligent programs that are able to differentiate clinically relevant changes as opposed to artificial changes and to display intelligent messages and/or diagnoses?
Kelkkanen, André K.; Lundqvist, Bengt I.; Nørskov, Jens K.
2009-07-01
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 of low-lying isomers and van der Waals (vdW) dispersion forces to give key contributions to the dissociation energy. The question raised whether functionals that incorporate vdW forces implicitly into the XC functional predict the correct lowest-energy structure for the water hexamer and yield accurate total dissociation energy is here answered affirmatively for the vdW-DF [M. Dion et al., Phys. Rev. Lett.92, 246401 (2004)].
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...
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
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.
The Microstructure and Chemical Bonds of β-C2S Under the High Energy Ball Grinding Function
Institute of Scientific and Technical Information of China (English)
无
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.
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
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.
Mechatronics by bond graphs an object-oriented approach to modelling and simulation
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. .
Functional Approach to Classical Yang-Mills Theories
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.
Defining mental disorder. Exploring the 'natural function' approach
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...
Energy Technology Data Exchange (ETDEWEB)
Bruce S. Hudson
2004-10-27
This project is directed at a fundamental understanding of hydrogen bonding, the primary reversible interaction leading to defined geometries, networks and supramolecular aggregates formed by organic molecules. Hydrogen bonding is still not sufficiently well understood that the geometry of such supramolecular aggregates can be predicted. In the approach taken existing quantum chemical methods capable of treating periodic solids have been applied to hydrogen bonded systems of known structure. The equilibrium geometry for the given space group and packing arrangement were computed and compared to that observed. The second derivatives and normal modes of vibration will then be computed and from this inelastic neutron scattering (INS) spectra were computed using the normal mode eigenvectors to compute spectral intensities. Appropriate inclusion of spectrometer line width and shape was made in the simulation and overtones, combinations and phonon wings were be included. These computed spectra were then compared with experimental results obtained for low-temperature polycrystalline samples at INS spectrometers at several facilities. This procedure validates the computational methodology for describing these systems including both static and dynamic aspects of the material. The resulting description can be used to evaluate the relative free energies of two or more proposed structures and so ultimately to be able to predict which structure will be most stable for a given building block.
International Nuclear Information System (INIS)
Gold clusters are of increasing interest due to a number of already established as well as new potential applications in different fields of nanotechnology. The use of gold nanoparticles can be significantly extended by surface modifications, sulfidation being the most popular. The identifications of preferred adsorption geometries, bond formation, and binding energies are helpful tools for understanding the properties of these particles. This study is focused on a 38-atom gold cluster passivated with 3-hydroxypropanthiolate linkers. Starting from the re-optimized global minimum structure of a bare 38-atom gold cluster (Doye and Wales 1998 New J. Chem. 22 733-44) and aiming at a description of the passivated particle, density functional theory calculations (within the framework of the Amsterdam density functional calculation package ADF 2006.01 (ADF2006.01, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com)) were performed at the level of the generalized gradient approximation of Perdew and Wang from 1991, with triple-zeta Slater basis sets plus p- and f-polarization functions (TZ2P) for the 33 outermost electrons of each gold atom, and considering scalar relativistic effects. Using this methodology, the space around the gold cluster (with the distance of the S of the thiolate from the gold cluster surface in the range 2.3-2.6 A) was examined to identify the most favourable absorption site for the thiolate linker. As a result, a 3D map was created and low energy areas corresponding to the potentially most favourable site for one 3-hydroxypropanthiolate linker on the gold cluster localized. Structures representing these areas were further optimized and consequently analysed using Mulliken population analysis to compare charge distribution over the tested structures, Mayer bond order analysis, as well as electron localization function/indicator bond formation analysis. The results obtained will be presented in comparison
Energy Technology Data Exchange (ETDEWEB)
Sihelnikova, L; Tvaroska, I [Institute of Chemistry, Slovak Academy of Sciences, Bratislava (Slovakia)
2008-02-13
Gold clusters are of increasing interest due to a number of already established as well as new potential applications in different fields of nanotechnology. The use of gold nanoparticles can be significantly extended by surface modifications, sulfidation being the most popular. The identifications of preferred adsorption geometries, bond formation, and binding energies are helpful tools for understanding the properties of these particles. This study is focused on a 38-atom gold cluster passivated with 3-hydroxypropanthiolate linkers. Starting from the re-optimized global minimum structure of a bare 38-atom gold cluster (Doye and Wales 1998 New J. Chem. 22 733-44) and aiming at a description of the passivated particle, density functional theory calculations (within the framework of the Amsterdam density functional calculation package ADF 2006.01 (ADF2006.01, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com)) were performed at the level of the generalized gradient approximation of Perdew and Wang from 1991, with triple-zeta Slater basis sets plus p- and f-polarization functions (TZ2P) for the 33 outermost electrons of each gold atom, and considering scalar relativistic effects. Using this methodology, the space around the gold cluster (with the distance of the S of the thiolate from the gold cluster surface in the range 2.3-2.6 A) was examined to identify the most favourable absorption site for the thiolate linker. As a result, a 3D map was created and low energy areas corresponding to the potentially most favourable site for one 3-hydroxypropanthiolate linker on the gold cluster localized. Structures representing these areas were further optimized and consequently analysed using Mulliken population analysis to compare charge distribution over the tested structures, Mayer bond order analysis, as well as electron localization function/indicator bond formation analysis. The results obtained will be presented in comparison
Sihelniková, L.; Tvaroška, I.
2008-02-01
Gold clusters are of increasing interest due to a number of already established as well as new potential applications in different fields of nanotechnology. The use of gold nanoparticles can be significantly extended by surface modifications, sulfidation being the most popular. The identifications of preferred adsorption geometries, bond formation, and binding energies are helpful tools for understanding the properties of these particles. This study is focused on a 38-atom gold cluster passivated with 3-hydroxypropanthiolate linkers. Starting from the re-optimized global minimum structure of a bare 38-atom gold cluster (Doye and Wales 1998 New J. Chem. 22 733-44) and aiming at a description of the passivated particle, density functional theory calculations (within the framework of the Amsterdam density functional calculation package ADF 2006.01 (ADF2006.01, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com)) were performed at the level of the generalized gradient approximation of Perdew and Wang from 1991, with triple-zeta Slater basis sets plus p- and f-polarization functions (TZ2P) for the 33 outermost electrons of each gold atom, and considering scalar relativistic effects. Using this methodology, the space around the gold cluster (with the distance of the S of the thiolate from the gold cluster surface in the range 2.3-2.6 Å) was examined to identify the most favourable absorption site for the thiolate linker. As a result, a 3D map was created and low energy areas corresponding to the potentially most favourable site for one 3-hydroxypropanthiolate linker on the gold cluster localized. Structures representing these areas were further optimized and consequently analysed using Mulliken population analysis to compare charge distribution over the tested structures, Mayer bond order analysis, as well as electron localization function/indicator bond formation analysis. The results obtained will be presented in comparison
Sihelniková, L; Tvaroška, I
2008-02-13
Gold clusters are of increasing interest due to a number of already established as well as new potential applications in different fields of nanotechnology. The use of gold nanoparticles can be significantly extended by surface modifications, sulfidation being the most popular. The identifications of preferred adsorption geometries, bond formation, and binding energies are helpful tools for understanding the properties of these particles. This study is focused on a 38-atom gold cluster passivated with 3-hydroxypropanthiolate linkers. Starting from the re-optimized global minimum structure of a bare 38-atom gold cluster (Doye and Wales 1998 New J. Chem. 22 733-44) and aiming at a description of the passivated particle, density functional theory calculations (within the framework of the Amsterdam density functional calculation package ADF 2006.01 (ADF2006.01, SCM, Theoretical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands, http://www.scm.com)) were performed at the level of the generalized gradient approximation of Perdew and Wang from 1991, with triple-zeta Slater basis sets plus p- and f-polarization functions (TZ2P) for the 33 outermost electrons of each gold atom, and considering scalar relativistic effects. Using this methodology, the space around the gold cluster (with the distance of the S of the thiolate from the gold cluster surface in the range 2.3-2.6 Å) was examined to identify the most favourable absorption site for the thiolate linker. As a result, a 3D map was created and low energy areas corresponding to the potentially most favourable site for one 3-hydroxypropanthiolate linker on the gold cluster localized. Structures representing these areas were further optimized and consequently analysed using Mulliken population analysis to compare charge distribution over the tested structures, Mayer bond order analysis, as well as electron localization function/indicator bond formation analysis. The results obtained will be presented in
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.
Combining Formal and Functional Approaches to Topic Structure
Zellers, Margaret; Post, Brechtje
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 kind of variation. We argue that it is fruitful to…
AN ENERGY FUNCTION APPROACH FOR FINDING ROOTS OF CHARACTERISTIC EQUATION
Directory of Open Access Journals (Sweden)
Deepak Mishra
2011-07-01
Full Text Available In this paper, an energy function approach for finding roots of a characteristic equation has been proposed. Finding the roots of a characteristics equation is considered as an optimization problem. We demonstrated that this problem can be solved with the application of feedback type neural network. The proposed approach is fast and robust against variation of parameter.
Combining formal and functional approaches to topic structure
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
Revisiting the European sovereign bonds with a permutation-information-theory approach
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.
Elkabetz, Yechiel; Ofir, Ayala; Argon, Yair; Bar-Nun, Shoshana
2008-01-01
Disulfide bonds within and between proteins are responsible for stabilizing folding and covalent assembly. They are thought to form by an obligatory pathway that leads to a single native structure compatible with secretion. We have previously demonstrated that the intradomain disulfide in the CH1 domain of the Ig γ2b heavy chains was dispensable for secretion (Elkabetz et al., 2005). Here we show that the heavy chain-light chain interchain disulfide is also dispensable. γ2b with mutated Cys12...
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.
Morioku, Kumika; Morimoto, Naoki; Takeuchi, Yasuo; Nishina, Yuta
2016-01-01
Oxidative C-H coupling reactions were conducted using graphene oxide (GO) as an oxidant. GO showed high selectivity compared with commonly used oxidants such as (diacetoxyiodo) benzene and 2,3-dichloro-5,6-dicyano-p-benzoquinone. A mechanistic study revealed that radical species contributed to the reaction. After the oxidative coupling reaction, GO was reduced to form a material that shows electron conductivity and high specific capacitance. Therefore, this system could concurrently achieve two important reactions: C-C bond formation via C-H transformation and production of functionalized graphene. PMID:27181191
International Nuclear Information System (INIS)
The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I2, At2, IO+, and AtO+ species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakens the covalent character of the bond in At2 even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems
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.
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.
International Nuclear Information System (INIS)
We have evaluated the kinetic isotope effect (KIE) in the proton transfer step that determines the oxidation rate of methylamine, catalyzed by the enzyme methylamine dehydrogenase. Calculations were performed with the wave function propagation (WFP) approach, recently implemented to estimate the KIE in soybean lipoxygenase-1. Two different versions of the method were applied. Both of them produced results which are close to the experimental value of 16.8 ± 0.5. The calculation required the development of a valence-bond parameterization. In the article, we describe the procedure followed to obtain these parameters, present the results of several tests employed to assess their performance and give details of the two versions of the WFP approach used to evaluate the KIE.
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
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.
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)
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.
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
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.
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 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...... calculation. 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...
A probabilistic approach to delineating functional brain regions
DEFF Research Database (Denmark)
Kalbitzer, Jan; Svarer, Claus; Frokjaer, Vibe G;
2009-01-01
The purpose of this study was to develop a reliable observer-independent approach to delineating volumes of interest (VOIs) for functional brain regions that are not identifiable on structural MR images. The case is made for the raphe nuclei, a collection of nuclei situated in the brain stem known...... compared with a manual delineation approach. RESULTS: In addition to providing an observer-independent solution, the probabilistic map approach returned a higher specific binding determined in a larger region, ultimately providing better data fitting in kinetic modeling. CONCLUSION: We developed a fast...
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.
Application of Functional-notional Approach in Institutional Settings
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...
Dual Approach to the Study of Land Market Functioning
Liliya Oganesovna Oganesyan; Elena Nikolaevna Fedyunina
2015-01-01
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 th...
The local projection in the density functional theory plus U approach: A critical assessment
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.
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.
Generating function approach to reliability analysis of structural systems
Institute of Scientific and Technical Information of China (English)
无
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.
International Nuclear Information System (INIS)
An analytical solution is developed for analysis of functionally graded material (FGM) beams containing two layers of piezoelectric material, used as sensor and actuator. The properties of FGM layer are functionally graded in the thickness direction according to the volume fraction power law distribution. The equations of motion are derived by using Hamilton's principle, based on the first-order shear deformation theory. By using a displacement potential function, and assumption of harmonic vibration, the equations of motion have been solved analytically. Finally, the effects of FGM constituent volume fraction in the peak responses for various volume fraction indexes have been graphically illustrated
Hong, Gongyi; Rosta, Edina; Warshel, Arieh
2006-10-01
The empirical valence bond (EVB) model provides an extremely powerful way for modeling and analyzing chemical reactions in solutions and proteins. However, this model is based on the unverified assumption that the off diagonal elements of the EVB Hamiltonian do not change significantly upon transfer of the reacting system from one phase to another. This ad hoc assumption has been rationalized by its consistency with empirically observed linear free energy relationships, as well as by other qualitative considerations. Nevertheless, this assumption has not been rigorously established. The present work explores the validity of the above EVB key assumption by a rigorous numerical approach. This is done by exploiting the ability of the frozen density functional theory (FDFT) and the constrained density functional theory (CDFT) models to generate convenient diabatic states for QM/MM treatments, and thus to examine the relationship between the diabatic and adiabatic surfaces, as well as the corresponding effective off diagonal elements. It is found that, at least for the test case of S(N)()2 reactions, the off diagonal element does not change significantly upon moving from the gas phase to solutions and thus the EVB assumption is valid and extremely useful. PMID:17004821
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...
Sequential approach to Colombeau's theory of generalized functions
International Nuclear Information System (INIS)
J.F. Colombeau's generalized functions are constructed as equivalence classes of the elements of a specially chosen ultrapower of the class of the C∞-functions. The elements of this ultrapower are considered as sequences of C∞-functions, so in a sense, the sequential construction presented here refers to the original Colombeau theory just as, for example, the Mikusinski sequential approach to the distribution theory refers to the original Schwartz theory of distributions. The paper could be used as an elementary introduction to the Colombeau theory in which recently a solution was found to the problem of multiplication of Schwartz distributions. (author). Refs
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...
Questionnaire of Executive Function for Dancers: An Ecological Approach
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,…
Matrix converter controlled with the direct transfer function approach
DEFF Research Database (Denmark)
Rodriguez, J.; Silva, E.; Blaabjerg, Frede;
2005-01-01
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...
The Foldy-Wouthuysen transformation from a functional integral approach
International Nuclear Information System (INIS)
The Foldy-Wouthuysen transformation is obtained from the functional integral, Lagrangian, approach. As a toy model we used the QCD Lagrangian. This leads to a derivation of the effective Lagrangian for non-relativistic quantum chromodynamics and the heavy quarks effective field theory. (Author)
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.
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.
Oxy-functionalization of nucleophilic rhenium(I) metal carbon bonds catalyzed by selenium(IV)
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...
Järvinen, Anna; Ng, Rowena; Bellugi, Ursula
2015-11-01
Williams syndrome (WS) is a neurogenetic disorder that is saliently characterized by a unique social phenotype, most notably associated with a dramatically increased affinity and approachability toward unfamiliar people. Despite a recent proliferation of studies into the social profile of WS, the underpinnings of the pro-social predisposition are poorly understood. To this end, the present study was aimed at elucidating approach behavior of individuals with WS contrasted with typical development (TD) by employing a multidimensional design combining measures of autonomic arousal, social functioning, and two levels of approach evaluations. Given previous evidence suggesting that approach behaviors of individuals with WS are driven by a desire for social closeness, approachability tendencies were probed across two levels of social interaction: talking versus befriending. The main results indicated that while overall level of approachability did not differ between groups, an important qualitative between-group difference emerged across the two social interaction contexts: whereas individuals with WS demonstrated a similar willingness to approach strangers across both experimental conditions, TD individuals were significantly more willing to talk to than to befriend strangers. In WS, high approachability to positive faces across both social interaction levels was further associated with more normal social functioning. A novel finding linked autonomic responses with willingness to befriend negative faces in the WS group: elevated autonomic responsivity was associated with increased affiliation to negative face stimuli, which may represent an autonomic correlate of approach behavior in WS. Implications for underlying organization of the social brain are discussed. PMID:26459097
Miranda Olff; Zhonglin Tan
2014-01-01
Background The study examined the prevalence of trauma and posttraumatic stress disorder (PTSD) symptoms among community dwelling Chinese adults in Hong Kong. The relationship of traumatic life events (including loss) and mental health has been investigated. Methods The sampling of the collaborative study (HKMMS: Hong Kong Mental Morbidity Survey) adopts a multi-stage stratification approach with the distribution of residential premises in different geographical districts and the relative pro...
Reaction Development on π- and σ-Conjugated Bonds and Creation of Innovative Functions.
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
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
A hybrid-exchange density functional study of the bonding and electronic structure in bulk CuFeS2
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.
Green's function approach to edge states in transition metal dichalcogenides
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.
An Evolutionary Computation Approach to Examine Functional Brain Plasticity.
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
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
Seo, Pill Won; Ahmed, Imteaz; Jhung, Sung Hwa
2016-06-01
Denitrogenation of a model fuel was studied by employing the adsorption of indole (IND) and quinoline (QUI) over a metal-organic framework (MOF), MIL-101, with or without functionalization. Five MIL-101 MOFs were obtained by direct syntheses, grafting, and hydrogenation. The adsorption capacity of IND increased significantly (up to 1.7 times that of MIL-101) upon introducing amino functional groups into MIL-101, despite the decrease in the porosity of the MOF after modification. However, the adsorption of QUI decreased when MIL-101 was modified using both amino and butyl groups because of the reduced porosity. The adsorption capacity for IND (based on the unit surface area of MIL-101s) showed that MIL-101s with amino groups had an adsorption capacity of around 2.3 times those of MIL-101 or MIL-101 with butyl groups, showing the importance of H-bonds for the adsorption of IND over MIL-101s. However, for the adsorption of QUI, only the porosity is important, and coordination of QUI on open metal sites does not play a dominant role, probably because of the low basicity of QUI. Moreover, there is little contribution of H-bonds (between N of QUI and H of -NH2 of MOF) in the adsorption of QUI over amino-MIL-101s, and this is probably due to a similar reason. Preparation methods for MIL-101 having a free amino group did not have any effect on the adsorption (based on surface area) of QUI or IND. PMID:27117231
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
Elements of a function analytic approach to probability.
Energy Technology Data Exchange (ETDEWEB)
Ghanem, Roger Georges (University of Southern California, Los Angeles, CA); Red-Horse, John Robert
2008-02-01
We first provide a detailed motivation for using probability theory as a mathematical context in which to analyze engineering and scientific systems that possess uncertainties. We then present introductory notes on the function analytic approach to probabilistic analysis, emphasizing the connections to various classical deterministic mathematical analysis elements. Lastly, we describe how to use the approach as a means to augment deterministic analysis methods in a particular Hilbert space context, and thus enable a rigorous framework for commingling deterministic and probabilistic analysis tools in an application setting.
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.
Directory of Open Access Journals (Sweden)
Y. Sajeev
2015-08-01
Full Text Available The equation-of-motion coupled cluster (EOMCC method based on the excited state Hartree-Fock (ESHF solutions is shown to be appropriate for computing the entire ground state potential energy curves of strongly correlated higher-order bonds. The new approach is best illustrated for the homolytic dissociation of higher-order bonds in molecules. The required multireference character of the true ground state wavefunction is introduced through the linear excitation operator of the EOMCC method. Even at the singles and doubles level of cluster excitation truncation, the nonparallelity error of the ground state potential energy curve from the ESHF based EOMCC method is small.
International Nuclear Information System (INIS)
A new approach of the combined effects of quantum direct and indirect dampings (within the adiabatic approximation) on the infrared lineshapes of the νX-H stretching mode of simple and single weak H-bonds is proposed. The approach is based on our precedent model dealing only with bare weak H-bonds [B. Boulil, O. Henri-Rousseau , P. Blaise Chem. Phys. 126 (1988) 263; B. Boulil, J.-L. Dejardin, N. El-Ghandour, O. Henri-Rousseau, J. Mol. Struct. (Theochem) 314 (1994) 83]. As in this initial model, the indirect relaxation of the H-bond bridge is described by the aid of the driven damped quantum harmonic oscillator model [W. Louisell, L. Walker, Phys. Rev. 137 (1965) 204]. It is shown that the Hamiltonian characterizing the driven damped quantum harmonic oscillator may be obtained in a non-Hermitean reduced form, allowing, contrarily to the initial approach, the possibility of generalizations to more complex situations than those of bare H-bonds
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.
Unified approach to partition functions of RNA secondary structures.
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. PMID:24177391
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.
Green's function approach for quantum graphs: an overview
Andrade, Fabiano M.(Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, Ponta Grossa, PR, 84030-900, Brazil); Schmidt, Alexandre G M; Vicentini, Eduardo; Cheng, Bin K.; da Luz, Marcos G. E.
2016-01-01
Here we review the many interesting 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. Such approach is particularly interesting because $G$ can be written as a sum over classical-like paths, where local quantum effects are taking into account through the scattering matrix amplitudes (basically, transmission and reflection coefficients) defined on each one...
Elliptic Cylindrical Invisibility Cloak, a Semianalytical Approach Using Mathieu Functions
Cojocaru, E.
2008-01-01
An elliptic cylindrical wave expansion method by using Mathieu functions is developed to obtain the scattering field for a two-dimensional elliptic cylindrical invisibility cloak. The cloak material parameters are obtained from the spatial transformation approach. A near-ideal model of the invisibility cloak is set up to solve the boundary problem at the inner boundary in the cloak shell. The proposed design provides a more practical cloak geometry when compared to previous designs of ellipti...
Nonequilibrium Green's function approach to mesoscopic thermal transport
Wang, Jian-Sheng; Jian WANG; Zeng, Nan
2006-01-01
We present a formulation of a nonequilibrium Green's function method for thermal current in nanojunction atomic systems with nonlinear interactions. This first-principle approach is applied to the calculation of the thermal conductance in carbon nanotube junctions. It is shown that nonlinearity already becomes important at low temperatures. Nonlinear interactions greatly suppress phonon transmission at room temperature. The peak of thermal conductance is found to be around 400K, in good agree...
Mechanistic approaches to the study of evolution: the functional synthesis
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...
PROCESS OF IDENTIFYING COMPETENCIES BASED ON A FUNCTIONAL APPROACH
NAOUFAL SEFIANI; ABDERAZAK BOUMANE; JEAN-PIERRE CAMPAGNE; DRISS BOUAMI
2012-01-01
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 (characteriz...
A zeta function approach to the semiclassical quantization of maps
International Nuclear Information System (INIS)
The quantum analogue of an area preserving map on a compact phase space is a unitary (evolution) operator which can be represented by a matrix of dimension L∝ℎ-1. The semiclassical theory for spectrum of the evolution operator will be reviewed with special emphasize on developing a dynamical zeta function approach, similar to the one introduced recently for a semiclassical quantization of hamiltonian systems. (author)
Fuzzy set approach to quality function deployment: An investigation
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
Magnetic Resonance and Brain Function. Approaches from Physics
International Nuclear Information System (INIS)
In the last decade of this millennium, while, on the one hand, the international scientific community has focused with increasing endeavour on the research about the great unknown of the mechanism and the pathologies of the human brain, on the other hand, the NMR community has achieved some important results, which should widely affect, in the future, the possibility of understanding the function and disfunction of the human brain. In the early 1980's, the beginning of the application of Magnetic Resonance Imaging (MRI) to the morphological study of the brain in vivo, has played an extraordinary role, which, since then, placed MRI in a leading position among the methodologies used for investigation and diagnostics of the Central Nervous System. In the 1990s, the objective of finding new means, based on MRI, capable of giving functional and metabolic information, with the highest possible space resolution, drove the scientists towards different approaches. Among these, the first one to generate a breakthrough in the localization of specific cerebral functions was the Blood Oxygen Level Development (BOLD) MRI. A very wide range of applications followed the discovery of BOLD imaging. Still, this method gives an indirect information of the localization of functions, via the variation of oxygen release and deoxyhemoglobin formation. Of course, a high-resolution spatial distribution of the metabolites, crucial to brain function, would give a deeper insight into the occurring processes. This finality is aimed at by the Double Magnetic Resonance methods, which are developing new procedures able to detect some metabolites with increasing sensitivity and resolution. A third new promising approach to functional MRI should derive from the use of hyperpolarized, opens a series of potential applications to the study of brain function
Garcia, Martin E.; Bennemann, K. H.
1994-01-01
We use a microscopic theory to describe the dynamics of the valence electrons in divalent-metal clusters. The theory is based on a many-body model Harniltonian H which takes into account, on the same electronic level, the van der Waals and the covalent bonding. In order to study the ground-state properties of H we have developed an extended slave-boson method. We have studied the bonding character and the degree of electronic delocalization in Hg_n clusters as a function of cluste...
Quantum transport through anisotropic molecular magnets: Hubbard Green function approach
International Nuclear Information System (INIS)
We extend the Green function approach to quantum transport through an anisotropic molecular magnet system with the help of Hubbard operators. Based on the single molecular magnet model, we reformulate the large spin and the total Hamiltonian in the language of Hubbard operators and obtain analytical expressions of the retarded Green function in sequential tunneling and Kondo regimes. In addition to this, we show the connection of our method to the master equation method in sequential regime and discuss a simple isotropic case in Kondo regime, in which we find a three-peak Kondo structure, a feature characterizing the isotropic exchange interaction between the localized electron and large spin. -- Highlights: ► We study transport through single molecular magnets by Green function approach. ► Large spin is expressed by Hubbard operators. ► Analytical formulas for the retarded Green's function are derived in two regimes. ► The connection of our method to the master equation is discussed. ► We find a three-peak Kondo structure.
A New Approach to Estimating the Bellman Function
Czech Academy of Sciences Publication Activity Database
Zeman, Jan
Praha: ÚTIA, AV ČR, 2009 - (Hofman, R.; Šmídl, V.; Pavelková, L.), s. 1-5 ISBN 978-80-903834-3-2. [10th International PhD Workshop on Systems and Control a Young Generation Viewpoint. Hluboká nad Vltavou (CZ), 22.09.2009-26.09.2009] R&D Projects: GA MŠk 2C06001; GA ČR GA102/08/0567 Institutional research plan: CEZ:AV0Z10750506 Keywords : dynamic programming * Bellman function * value function Subject RIV: BD - Theory of Information http://library.utia.cas.cz/separaty/2009/AS/zeman-a new approach to estimating the bellman function.pdf
Systems approaches to microbial communities and their functioning.
Röling, Wilfred F M; Ferrer, Manuel; Golyshin, Peter N
2010-08-01
Recent advances in molecular microbial ecology and systems biology enhance insight into microbial community structure and functioning. They provide conceptual and technical bases for the translation of species-data and community-data into a model framework accounting for the functioning of and interactions between metabolic networks of species in multispecies environments. Function-directed and single cell-directed approaches supplement and improve metagenomics-derived community information. The topology of the metabolic network, reconstructed from a species' genome sequence, provides insight into its metabolic environments and interactions with other microorganisms. Progress in the theoretical and experimental analysis of flux through metabolic networks paves the way for their application at the community level, contributing to understanding of material flows between and within species and their resilience toward perturbations. PMID:20637597
Controlled Chemistry Approach to the Oxo-Functionalization of Graphene.
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
Density functional approach for pairing in finite size systems
International Nuclear Information System (INIS)
The combination of functional theory where the energy is written as a functional of the density, and the configuration mixing method, provides an efficient description of nuclear ground and excited state properties. The specific pathologies that have been recently observed, show the lack of a clear underlying justification associated to the breaking and the restoration of symmetries within density functional theory. This thesis focuses on alternative treatments of pairing correlations in finite many body systems that consider the breaking and the restoration of the particle number conservation. The energy is written as a functional of a projected quasi-particle vacuum and can be linked to the one obtained within the configuration mixing framework. This approach has been applied to make the projection either before or after the application of the variational principle. It is more flexible than the usual configuration mixing method since it can handle more general effective interactions than the latter. The application to the Krypton isotopes shows the feasibility and the efficiency of the method to describe pairing near closed shell nuclei. Following a parallel path, a theory where the energy is written as a functional of the occupation number and natural orbitals is proposed. The new functional is benchmarked in an exactly solvable model, the pairing Hamiltonian. The efficiency and the applicability of the new theory have been tested for various pairing strengths, single particle energy spectra and numbers of particles. (author)
International Nuclear Information System (INIS)
Graphical abstract: The electronic properties such as the static dipole polarizability, anisotropy of the polarizability, and dipole moment of yttrium bromide, YBr (X1Σ) have been theoretically studied. Highlights: → Conventional ab initio and density functional theory methods were employed to study linear optical properties of YBr molecule. → Properties derivatives and their level of theory dependence were studied. → 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, α-bar, anisotropy of the polarizability, Δα, and dipole moment, μ, 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.
Density function theoretical study on the complex involved in Th atom-activated C–C bond in C2H6
Qing-Qing, Wang; Peng, Li; Tao, Gao; Hong-Yan, Wang; Bing-Yun, Ao
2016-06-01
Density functional theory (DFT) calculations are performed to investigate the reactivity of Th atom toward ethane C–C bond activation. A comprehensive description of the reaction mechanisms leading to two different reaction products is presented. We report a complete exploration of the potential energy surfaces by taking into consideration different spin states. In addition, the intermediate and transition states along the reaction paths are characterized. Total, partial, and overlap population density of state diagrams and analyses are also presented. Furthermore, the natures of the chemical bonding of intermediate and transition states are studied by using topological method combined with electron localization function (ELF) and Mayer bond order. Infrared spectrum (IR) is obtained and further discussed based on the optimized geometries. Project supported by the National Natural Science Foundation of China (Grant Nos. 21371160, 21401173, and 11364023).
International Nuclear Information System (INIS)
We propose a kinetic energy density functional scheme with nonlocal terms based on the von Weizsaecker functional, instead of the more traditional approach where the nonlocal terms have the structure of the Thomas-Fermi functional. The proposed functionals recover the exact kinetic energy and reproduce the linear response function of homogeneous electron systems. In order to assess their quality, we have tested the total kinetic energies as well as the kinetic energy density for atoms. The results show that these nonlocal functionals give as good results as the most sophisticated functionals in the literature. The proposed scheme for constructing the functionals means a step ahead in the field of fully nonlocal kinetic energy functionals, because they are capable of giving better local behavior than the semilocal functionals, yielding at the same time accurate results for total kinetic energies. Moreover, the functionals enjoy the possibility of being evaluated as a single integral in momentum space if an adequate reference density is defined, and then quasilinear scaling for the computational cost can be achieved
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.)
Nuclear Functions of Nucleolin through Global Proteomics and Interactomic Approaches.
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
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
Sensorimotor integration for functional recovery and the Bobath approach.
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
The Navier-Stokes equations an elementary functional analytic approach
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...
A novel Bayesian approach to spectral function reconstruction
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.
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.
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 %...
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…
An information theoretic approach to the functional classification of neurons
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.
Novel metal resistance genes from microorganisms: a functional metagenomic approach.
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
Current approaches on viral infection: proteomics and functional validations
Directory of Open Access Journals (Sweden)
JieZheng
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.
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.
Green's function approach for quantum graphs: An overview
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.
Wall function approach for boiling two-phase flows
International Nuclear Information System (INIS)
One of the important goals of the NURESIM project is to assess and improve the simulation capability of the three-dimensional two-fluid codes for prediction of local boiling flow processes. The boiling flow is strongly affected by local mechanisms in the turbulent boundary layer near the heated wall. Wall-to-fluid transfer models for boiling flow with the emphasis on near-wall treatment are being addressed in the paper. Since the computational grid of the 3D two-fluid models is too coarse to resolve the variable gradients in the near-wall region, the use of wall functions is a common approach to model the liquid velocity and temperature profile adjacent to the heated wall. The wall function model for momentum, based on the surface roughness analogy has been discussed and implemented in the NEPTUNECFD code. The model has been validated on several upward boiling flow experiments, differing in the geometry, working fluid and operating conditions. The simulations with the new wall function model show an improved prediction of flow parameters over the boiling boundary layer. Furthermore, a wall function model for the energy equation, based on enhanced two-phase wall friction has been derived and validated.
A traveling salesman approach for predicting protein functions
Directory of Open Access Journals (Sweden)
Johnson Olin
2006-10-01
Full Text Available Abstract Background Protein-protein interaction information can be used to predict unknown protein functions and to help study biological pathways. Results Here we present a new approach utilizing the classic Traveling Salesman Problem to study the protein-protein interactions and to predict protein functions in budding yeast Saccharomyces cerevisiae. We apply the global optimization tool from combinatorial optimization algorithms to cluster the yeast proteins based on the global protein interaction information. We then use this clustering information to help us predict protein functions. We use our algorithm together with the direct neighbor algorithm 1 on characterized proteins and compare the prediction accuracy of the two methods. We show our algorithm can produce better predictions than the direct neighbor algorithm, which only considers the immediate neighbors of the query protein. Conclusion Our method is a promising one to be used as a general tool to predict functions of uncharacterized proteins and a successful sample of using computer science knowledge and algorithms to study biological problems.
The Navier-Stokes equations an elementary functional analytic approach
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 ...
Electronic excitations: density-functional versus many-body Green's-function approaches
Onida, Giovanni; Reining, Lucia; Rubio, Angel
2002-04-01
Electronic excitations lie at the origin of most of the commonly measured spectra. However, the first-principles computation of excited states requires a larger effort than ground-state calculations, which can be very efficiently carried out within density-functional theory. On the other hand, two theoretical and computational tools have come to prominence for the description of electronic excitations. One of them, many-body perturbation theory, is based on a set of Green's-function equations, starting with a one-electron propagator and considering the electron-hole Green's function for the response. Key ingredients are the electron's self-energy Σ and the electron-hole interaction. A good approximation for Σ is obtained with Hedin's GW approach, using density-functional theory as a zero-order solution. First-principles GW calculations for real systems have been successfully carried out since the 1980s. Similarly, the electron-hole interaction is well described by the Bethe-Salpeter equation, via a functional derivative of Σ. An alternative approach to calculating electronic excitations is the time-dependent density-functional theory (TDDFT), which offers the important practical advantage of a dependence on density rather than on multivariable Green's functions. This approach leads to a screening equation similar to the Bethe-Salpeter one, but with a two-point, rather than a four-point, interaction kernel. At present, the simple adiabatic local-density approximation has given promising results for finite systems, but has significant deficiencies in the description of absorption spectra in solids, leading to wrong excitation energies, the absence of bound excitonic states, and appreciable distortions of the spectral line shapes. The search for improved TDDFT potentials and kernels is hence a subject of increasing interest. It can be addressed within the framework of many-body perturbation theory: in fact, both the Green's functions and the TDDFT approaches profit
Simonetti, S.; Compañy, A. Díaz; Pronsato, E.; Juan, A.; Brizuela, G.; Lam, A.
2015-12-01
Silica-based mesoporous materials have been recently proposed as an efficient support for the controlled release of a popular anticancer drug, 5-fluorouracil (5-FU). Although the relevance of this topic, the atomistic details about the specific surface-drug interactions and the energy of adsorption are almost unknown. In this work, theoretical calculations using the Vienna Ab-initio Simulation Package (VASP) applying Grimme's-D2 correction were performed to elucidate the drug-silica interactions and the host properties that control 5-FU drug adsorption on β-cristobalite (1 1 1) hydroxylated surface. This study shows that hydrogen bonding, electron exchange, and dispersion forces are mainly involved to perform the 5-FU adsorption onto silica. This phenomenon, revealed by favorable energies, results in optimum four adsorption geometries that can be adopted for 5-FU on the hydroxylated silica surface. Silanols are weakening in response to the molecule approach and establish H-bonds with polar groups of 5-FU drug. The final geometry of 5-FU adopted on hydroxylated silica surface is the results of H-bonding interactions which stabilize and fix the molecule to the surface and dispersion forces which approach it toward silica (1 1 1) plane. The level of hydroxylation of the SiO2 (1 1 1) surface is reflected by the elevated number of hydrogen bonds that play a significant role in the adsorption mechanisms.
Functional renormalization-group approach to decaying turbulence
International Nuclear Information System (INIS)
We reconsider the functional renormalization-group (FRG) approach to decaying Burgers turbulence, and extend it to decaying Navier–Stokes and surface quasi-geostrophic turbulence. The method is based on a renormalized small-time expansion, equivalent to a loop expansion, and naturally produces a dissipative anomaly and a cascade after a finite time. We explicitly calculate and analyze the one-loop FRG equations in the zero-viscosity limit as a function of the dimension. For Burgers turbulence they reproduce the FRG equation obtained in the context of random manifolds, extending previous results of one of us. Breakdown of energy conservation due to shocks and the appearance of a direct energy cascade corresponds to failure of dimensional reduction in the context of disordered systems. For Navier–Stokes turbulence in three dimensions, the velocity–velocity correlation function acquires a linear dependence on the distance, ζ2 = 1, in the inertial range, instead of Kolmogorov’s ζ2 = 2/3; however, the possibility remains for corrections at two- or higher-loop order. In two dimensions, we obtain a numerical solution which conserves energy and exhibits an inverse cascade, with explicit analytical results for both large and small distances, in agreement with the scaling proposed by Batchelor. In large dimensions, the one-loop FRG equation for Navier–Stokes turbulence converges to that of Burgers turbulence. (paper)
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.
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.
Functional Analysis of Jasmonates in Rice through Mutant Approaches
Dhakarey, Rohit; Kodackattumannil Peethambaran, Preshobha; Riemann, Michael
2016-01-01
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. PMID:27135235
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.
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.
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.
International Nuclear Information System (INIS)
A first-principles study of critical temperatures (Tc) of spin crossover (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the Tc of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔEHL and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract Tc by exploiting the ΔH/T − T and ΔS − T relationships. The results are in agreement with experiment. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in Tc of the two phases. This study shows the applicability of the DFT+U approach for predicting Tc of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior
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Khandaker M
2016-02-01
Full Text Available Morshed Khandaker,1,4 Shahram Riahinezhad,1 Fariha Sultana,1 Melville B Vaughan,2,4 Joshua Knight,2 Tracy L Morris3,4 1Department of Engineering & Physics, 2Department of Biology, 3Department of Mathematics and Statistics, 4Center for Interdisciplinary Biomedical Education and Research, University of Central Oklahoma, Edmond, OK, USA Abstract: Implant failure due to poor integration of the implant with the surrounding biomaterial is a common problem in various orthopedic and orthodontic surgeries. Implant fixation mostly depends upon the implant surface topography. Micron to nanosize circular-shaped groove architecture with adequate surface roughness can enhance the mechanical interlock and osseointegration of an implant with the host tissue and solve its poor fixation problem. Such groove architecture can be created on a titanium (Ti alloy implant by laser peening treatment. Laser peening produces deep, residual compressive stresses in the surfaces of metal parts, delivering increased fatigue life and damage tolerance. The scientific novelty of this study is the controlled deposition of circular-shaped rough spot groove using laser peening technique and understanding the effect of the treatment techniques for improving the implant surface properties. The hypothesis of this study was that implant surface grooves created by controlled laser peen treatment can improve the mechanical and biological responses of the implant with the adjoining biomaterial. The objective of this study was to measure how the controlled laser-peened groove architecture on Ti influences its osteoblast cell functions and bonding strength with bone cement. This study determined the surface roughness and morphology of the peen-treated Ti. In addition, this study compared the osteoblast cell functions (adhesion, proliferation, and differentiation between control and peen-treated Ti samples. Finally, this study measured the fracture strength between each kind of Ti samples
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
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
Recent molecular approaches to understanding astrocyte function in vivo
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Todd A Fiacco
2013-12-01
Full Text Available Astrocytes are a predominant glial cell type in the nervous systems, and are becoming recognized as important mediators of normal brain function as well as neurodevelopmental, neurological, and neurodegenerative brain diseases. Although numerous potential mechanisms have been proposed to explain the role of astrocytes in the normal and diseased brain, research into the physiological relevance of these mechanisms in vivo is just beginning. In this review, we will summarize recent developments in innovative and powerful molecular approaches, including knockout mouse models, transgenic mouse models, and astrocyte-targeted gene transfer/expression, which have led to advances in understanding astrocyte biology in vivo that were heretofore inaccessible to experimentation. We will examine the recently improved understanding of the roles of astrocytes - with an emphasis on astrocyte signaling - in the context of both the healthy and diseased brain, discuss areas where the role of astrocytes remains debated, and suggest new research directions.
A Functional Approach to the Heat Kernel in Curved Space
Martin, L
1996-01-01
The heat kernel $M_{xy} = $ is of central importance when studying the propagation of a scalar particle in curved space. It is quite convenient to analyze this quantity in terms of classical variables by use of the quantum mechanical path integral; regrettably it is not entirely clear how this path integral can be mathematically well defined in curved space. An alternate approach to studying the heat kernel in terms of classical variables was introduced by Onofri. This technique is shown to be applicable to problems in curved space; an unambiguous expression for $M_{xy}$ is obtained which involves functional derivatives of a classical quantity. We illustrate how this can be used by computing $M_{xx}$ to lowest order in the curvature scalar R.
A Goal-Function Approach to Analysis of Control Situations
DEFF Research Database (Denmark)
Lind, Morten
2010-01-01
The concept of situations plays a central role in all theories of meaning and context. and serve to frame or group events and other occurrences into coherent meaningful wholes. Situations are typed, may be interconnected and organized into higher level structures. In operation of industrial...... processes situations should identify operational aspects relevant for control agent’s decision making in plant supervision and control. Control situations can be understood as recurrent and interconnected patterns of control with important implications for control and HMI design. Goal-Function approaches to...... systems modeling like Multilevel Flow Modeling can be used to represent control situations. The paper will describe an action theoretical foundation for MFM and its use for the development of a theory of control situations....
CLARM: An integrative approach for functional modules discovery
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.
Promoting return of function in multiple sclerosis: An integrated approach.
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
PROCESS OF IDENTIFYING COMPETENCIES BASED ON A FUNCTIONAL APPROACH
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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.
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
Predicting activity approach based on new atoms similarity kernel function.
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. PMID:26117822
Convergent approaches for defining functional imaging endophenotypes in schizophrenia
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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
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...
A Model-Based Approach to Constructing Music Similarity Functions
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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.
Molecular Approaches to Functionalization of Dental Implant Surfaces
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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.
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 ...
ABOUT COMPLEX APPROACH TO MODELLING OF TECHNOLOGICAL MACHINES FUNCTIONING
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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
Convertible bond valuation focusing on Chinese convertible bond market
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-...
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.
Exponential wealth distribution : a new approach from functional iteration theory*
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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.
Executive Function and Food Approach Behavior in Middle Childhood
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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
A Functional Genomic Approach to Chlorinated Ethenes Bioremediation
Lee, P. K.; Brodie, E. L.; MacBeth, T. W.; Deeb, R. A.; Sorenson, K. S.; Andersen, G. L.; Alvarez-Cohen, L.
2007-12-01
With the recent advances in genomic sciences, a knowledge-based approach can now be taken to optimize the bioremediation of trichloroethene (TCE). During the bioremediation of a heterogeneous subsurface, it is vital to identify and quantify the functionally important microorganisms present, characterize the microbial community and measure their physiological activity. In our field experiments, quantitative PCR (qPCR) was coupled with reverse-transcription (RT) to analyze both copy numbers and transcripts expressed by the 16S rRNA gene and three reductive dehalogenase (RDase) genes as biomarkers of Dehalococcoides spp. in the groundwater of a TCE-DNAPL site at Ft. Lewis (WA) that was serially subjected to biostimulation and bioaugmentation. Genes in the Dehalococcoides genus were targeted as they are the only known organisms that can completely dechlorinate TCE to the innocuous product ethene. Biomarker quantification revealed an overall increase of more than three orders of magnitude in the total Dehalococcoides population and quantification of the more liable and stringently regulated mRNAs confirmed that Dehalococcoides spp. were active. Parallel with our field experiments, laboratory studies were conducted to explore the physiology of Dehalococcoides isolates in order to develop relevant biomarkers that are indicative of the metabolic state of cells. Recently, we verified the function of the nitrogenase operon in Dehalococcoides sp. strain 195 and nitrogenase-encoding genes are ideal biomarker targets to assess cellular nitrogen requirement. To characterize the microbial community, we applied a high-density phylogenetic microarray (16S PhyloChip) that simultaneous monitors over 8,700 unique taxa to track the bacterial and archaeal populations through different phases of treatment. As a measure of species richness, 1,300 to 1,520 taxa were detected in groundwater samples extracted during different stages of treatment as well as in the bioaugmentation culture. We
Selectionist and evolutionary approaches to brain function: a critical appraisal
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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.
A new Bayesian approach to the reconstruction of spectral functions
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 ...
Filtered density function approach for reactive transport in groundwater
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
Liang, Qiuhua; Jiang, Junke; Meng, Ruishen; Ye, Huaiyu; Tan, Chunjian; Yang, Qun; Sun, Xiang; Yang, Daoguo; Chen, Xianping
2016-06-28
Using density functional theory calculations with van der Waals correction, we show that the electronic properties (band gap and carrier mobility) and work functions of graphane/fully hydrogenated hexagonal boron nitride (G/fHBN) heterobilayers can be favorably tuned via heteronuclear dihydrogen bonding (C-HH-B and C-HH-N) and an external electric field. Our results reveal that G/fHBN heterobilayers have different direct band gaps of ∼1.2 eV and ∼3.5 eV for C-HH-B and C-HH-N bonds, respectively. In particular, these band gaps can be effectively modulated by altering the direction and strength of the external electric field (E-field), and correspondingly exhibit a semiconductor-metal transition. The conformation and stability of G/fHBN heterobilayers show a strong dependence on the heteronuclear dihydrogen bonding. Fantastically, these bonds are stable enough under a considerable external E-field as compared with other van der Waals (vdW) 2D layered materials. The mobilities of G/fHBN heterobilayers we predicted are hole-dominated, reasonably high (improvable up to 200 cm(2) V(-1) s(-1)), and extremely isotropic. We also demonstrate that the work function of G/fHBN heterobilayers is very sensitive to the external E-field and is extremely low. These findings make G/fHBN heterobilayers very promising materials for field-effect transistors and light-emitting devices, and inspire more efforts in the development of 2D material systems using weak interlayer interactions and electric field control. PMID:27265511
Vedernikov, Andrei N
2012-06-19
Atom economy and the use of "green" reagents in organic oxidation, including oxidation of hydrocarbons, remain challenges for organic synthesis. Solutions to this problem would lead to a more sustainable economy because of improved access to energy resources such as natural gas. Although natural gas is still abundant, about a third of methane extracted in distant oil fields currently cannot be used as a chemical feedstock because of a dearth of economically and ecologically viable methodologies for partial methane oxidation. Two readily available "atom-economical" "green" oxidants are dioxygen and hydrogen peroxide, but few methodologies have utilized these oxidants effectively in selective organic transformations. Hydrocarbon oxidation and C-H functionalization reactions rely on Pd(II) and Pt(II) complexes. These reagents have practical advantages because they can tolerate moisture and atmospheric oxygen. But this tolerance for atmospheric oxygen also makes it challenging to develop novel organometallic palladium and platinum-catalyzed C-H oxidation reactions utilizing O(2) or H(2)O(2). This Account focuses on these challenges: the development of M-C bond (M = Pt(II), Pd(II)) functionalization and related selective hydrocarbon C-H oxidations with O(2) or H(2)O(2). Reactions discussed in this Account do not involve mediators, since the latter can impart low reaction selectivity and catalyst instability. As an efficient solution to the problem of direct M-C oxidation and functionalization with O(2) and H(2)O(2), this Account introduces the use of facially chelating semilabile ligands such as di(2-pyridyl)methanesulfonate and the hydrated form of di(2-pyridyl)ketone that enable selective and facile M(II)-C(sp(n)) bond functionalization with O(2) (M = Pt, n = 3; M = Pd, n = 3 (benzylic)) or H(2)O(2) (M = Pd, n = 2). The reactions proceed efficiently in protic solvents such as water, methanol, or acetic acid. With the exception of benzylic Pd(II) complexes, the
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
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
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
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.
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%.
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.
Metatranscriptomic Approach to Analyze the Functional Human Gut Microbiota
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...
A copula-based approach to aggregation functions
Marta Cardin; Maddalena Manzi
2006-01-01
This paper presents the role of copula functions in the theory of aggregation operators and an axiomatic characterization of Archimedean aggregation functions. In this context we are focusing our attention about several properties of aggregation functions, like supermodularity and Schur-concavity.
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...
Functional integral approach to the kinetic theory of inhomogeneous systems
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...
A Reverse Genetic Approach to Test Functional Redundancy During Embryogenesis
Rikin, Amir; Rosenfeld, Gabriel E.; McCartin, Kellie; Evans, Todd
2010-01-01
Gene function during embryogenesis is typically defined by loss-of-function experiments, for example by targeted mutagenesis (knockout) in the mouse. In the zebrafish model, effective reverse genetic techniques have been developed using microinjection of gene-specific antisense morpholinos. Morpholinos target an mRNA through specific base-pairing and block gene function transiently by inhibiting translation or splicing for several days during embryogenesis (knockdown). However, in vertebrates...
Connectomics and new approaches for analyzing human brain functional connectivity
Craddock, R. Cameron; Tungaraza, Rosalia L; Milham, Michael P.
2015-01-01
Estimating the functional interactions between brain regions and mapping those connections to corresponding inter-individual differences in cognitive, behavioral and psychiatric domains are central pursuits for understanding the human connectome. The number and complexity of functional interactions within the connectome and the large amounts of data required to study them position functional connectivity research as a “big data” problem. Maximizing the degree to which knowledge about human br...
Functional Bipartite Ranking: a Wavelet-Based Filtering Approach
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...
COSMETICS AS THEMATIC TO APPROACH ORGANIC FUNCTIONS IN CHEMISTRY TEACHING
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...
The discourse functions of Italian subjects a centering approach
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.
The Motivational Function of Private Speech: An Experimental Approach.
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…
Metere, Alfredo; Dzugutov, Mikhail
2015-01-01
We present a new program able to perform unique visual analysis on generic particle systems: PASYVAT (PArticle SYstem Visual Analysis Tool). More specifically, it can perform a selection of multiple interparticle distance ranges from a radial distribution function (RDF) plot and display them in 3D as bonds. This software can be used with any data set representing a system of particles in 3D. In this manuscript the reader will find a description of the program and its internal structure, with emphasis on its applicability in the study of certain particle configurations, obtained from classical molecular dynamics simulation in condensed matter physics.
Recent approaches in physical modification of protein functionality.
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
Supersymmetric Valence Bond Solid States
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...
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.
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.
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)
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 are...
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.
Institute of Scientific and Technical Information of China (English)
无
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:
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.
A reproducing kernel Hilbert space approach to functional linear regression
Yuan, Ming; Cai, T. Tony
2012-01-01
We study in this paper a smoothness regularization method for functional linear regression and provide a unified treatment for both the prediction and estimation problems. By developing a tool on simultaneous diagonalization of two positive definite kernels, we obtain shaper results on the minimax rates of convergence and show that smoothness regularized estimators achieve the optimal rates of convergence for both prediction and estimation under conditions weaker than those for the functional...
Computational approaches for rational design of proteins with novel functionalities
Manish Kumar Tiwari; Ranjitha Singh; Raushan Kumar Singh; In-Won Kim; Jung-Kul Lee
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 ...
Path probability of stochastic motion: A functional approach
Hattori, Masayuki; Abe, Sumiyoshi
2016-06-01
The path probability of a particle undergoing stochastic motion is studied by the use of functional technique, and the general formula is derived for the path probability distribution functional. The probability of finding paths inside a tube/band, the center of which is stipulated by a given path, is analytically evaluated in a way analogous to continuous measurements in quantum mechanics. Then, the formalism developed here is applied to the stochastic dynamics of stock price in finance.
An evolutionary computation approach to examine functional brain plasticity
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 ...
An Evolutionary Computation Approach to Examine Functional Brain Plasticity
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 ...
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Maurice, Rémi, E-mail: remi.maurice@subatech.in2p3.fr; Montavon, Gilles [SUBATECH, CNRS UMR 6457, IN2P3/EMN Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3 (France); Réal, Florent; Gomes, André Severo Pereira; Vallet, Valérie [Laboratoire PhLAM, CNRS UMR 8523, Université de Lille, 59655 Villeneuve d’Ascq Cedex (France); Galland, Nicolas [CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3 (France)
2015-03-07
The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I{sub 2}, At{sub 2}, IO{sup +}, and AtO{sup +} species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakens the covalent character of the bond in At{sub 2} even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems.
Functional Approach to Phase Space Formulation of Quantum Mechanics
Aringazin, A K
1995-01-01
We present BRST gauge fixing approach to quantum mechanics in phase space. The theory is obtained by $\\hbar$-deformation of the cohomological classical mechanics described by d=1, N=2 model. We use the extended phase space supplied by the path integral formulation with $\\hbar$-deformed symplectic structure.
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.
Credit default swaps, bond spreads and the bond market
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...
Functional complexity and ecosystem stability: an experimental approach
International Nuclear Information System (INIS)
The complexity-stability hypothesis was experimentally tested using intact terrestrial microcosms. Functional complexity was defined as the number and significance of component interactions (i.e., population interactions, physical-chemical reactions, biological turnover rates) influenced by nonlinearities, feedbacks, and time delays. It was postulated that functional complexity could be nondestructively measured through analysis of a signal generated from the system. Power spectral analysis of hourly CO2 efflux, from eleven old-field microcosms, was analyzed for the number of low frequency peaks and used to rank the functional complexity of each system. Ranking of ecosystem stability was based on the capacity of the system to retain essential nutrients and was measured by net loss of Ca after the system was stressed. Rank correlation supported the hypothesis that increasing ecosystem functional complexity leads to increasing ecosystem stability. The results indicated that complex functional dynamics can serve to stabilize the system. The results also demonstrated that microcosms are useful tools for system-level investigations
Green's function approach for electron scattering through super lattice structure
International Nuclear Information System (INIS)
In the present paper, an alternative treatment for resonance scattering is developed, where the requirement of correct asymptotic behaviour is incorporated, in the frame of relativistic quantal mechanics. In this respect, analogous Siegert incoming- and outgoing- boundary conditions are employed, in which resonant internal energy Eigen-values that are embedded into super-lattice structures, are extended into the external region, and as a consequence the corresponding internal Eigen-functions become non orthogonal. Thereby, Green's equation is employed. This, and together with utilizing Dirac σ-function for the potential, enabled us to express explicitly the relativistic scattering coefficients, in terms of the Green's function, after being spectrally represented as a Mittage Leffler- expansion
Synergetic approach of norm and pathology of living system functioning
International Nuclear Information System (INIS)
Basing on fundamental idea of dynamical chaos and strict periodicity in living systems the new peculiarities in brain and heart functioning have been reveled. It has been shown that the development of pathological states of brain and heart activities occurs by means of both increase and decrease of chaos components in brain activity and heart rhythm. It has been defined the 'health range' for brain and heart functioning in norm, and the method of recovery of the health range is proposed from the electrocardiograms and electroencephalograms data (authors).
Approaches to organizing public relations functions in healthcare.
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
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
Geostatistics for functional data: an ordinary kriging approach
Giraldo, Ramón; Delicado Useros, Pedro Francisco; Mateu, Jorge
2007-01-01
We present a methodology to perform spatial prediction when measured data are curves. In particular, we propose both an estimator of the spatial correlation and a functional kriging predictor. We adapt an optimization criterium used in multi- variable spatial prediction in order to estimate the kriging parameters. A real data example on soil penetration resistences illustrates our proposals.
Mayer Transfer Operator Approach to Selberg Zeta Function
DEFF Research Database (Denmark)
Momeni, Arash; Venkov, Alexei
These notes are based on three lectures given by the second author at Copenhagen University (October 2009) and at Aarhus University, Denmark (December 2009). We mostly present here a survey of results of Dieter Mayer on relations between Selberg and Smale-Ruelle dynamical zeta functions. In a spe...
A Functional Approach to Televised Political Spots: Acclaiming, Attacking, Defending.
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…
Newer Approaches to Identify Potential Untoward Effects in Functional Foods.
Marone, Palma Ann; Birkenbach, Victoria L; Hayes, A Wallace
2016-03-01
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
Alternative approach for establishing the Nacelle Transfer Function
DEFF Research Database (Denmark)
Krishna, Vinay B.; Ormel, Frank; Hansen, Kurt Schaldemose
2016-01-01
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...
Generalized ODE approach to impulsive retarded functional differential equations
Czech Academy of Sciences Publication Activity Database
Federson, M.; Schwabik, Štefan
2006-01-01
Roč. 19, č. 11 (2006), s. 1201-1234. ISSN 0893-4983 R&D Projects: GA ČR(CZ) GA201/04/0690 Institutional research plan: CEZ:AV0Z10190503 Keywords : generalized ordinary differential equation * retarded functional differential equation Subject RIV: BA - General Mathematics
Constructing and Deriving Reciprocal Trigonometric Relations: A Functional Analytic Approach
Ninness, Chris; Dixon, Mark; Barnes-Holmes, Dermot; Rehfeldt, Ruth Anne; Rumph, Robin; McCuller, Glen; Holland, James; Smith, Ronald; Ninness, Sharon K.; McGinty, Jennifer
2009-01-01
Participants were pretrained and tested on mutually entailed trigonometric relations and combinatorially entailed relations as they pertained to positive and negative forms of sine, cosine, secant, and cosecant. Experiment 1 focused on training and testing transformations of these mathematical functions in terms of amplitude and frequency followed…
A Derivational Approach to the Operational Semantics of Functional Languages
DEFF Research Database (Denmark)
Biernacka, Malgorzata
We study the connections between different forms of operational semantics for functional programming languages and we present systematic methods of interderiving reduction semantics, abstract machines and higher-order evaluators. We first consider two methods based on program transformations: a s...
Newton Algorithms for Analytic Rotation: An Implicit Function Approach
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…
Filling the gap between sequence and function: a bioinformatics approach
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
Polarization and localization in insulators: Generating function approach
International Nuclear Information System (INIS)
We develop the theory and practical expressions for the full quantum-mechanical distribution of the intrinsic macroscopic polarization of an insulator in terms of the ground state wave function. The central quantity is a cumulant generating function, which yields, upon successive differentiation, all the cumulants and moments of the probability distribution of the center of mass X/N of the electrons, defined appropriately to remain valid for extended systems obeying twisted boundary conditions. The first moment is the average polarization, where we recover the well-known Berry phase expression. The second cumulant gives the mean-square fluctuation of the polarization, which defines an electronic localization length ξi along each direction i: ξi2=(i2>-i>2)/N. It follows from the fluctuation-dissipation theorem that in the thermodynamic limit ξi diverges for metals and is a finite, measurable quantity for insulators. In noninteracting systems ξi2 is related to the spread of the Wannier functions. It is possible to define for correlated insulators maximally localized ''many-body Wannier functions,'' which for large N become localized in disconnected regions of the high-dimensional configuration space, establishing a direct connection with Kohn's theory of the insulating state. Interestingly, the expression for ξi2, which involves the second derivative of the wave function with respect to the boundary conditions, is directly analogous to Kohn's formula for the ''Drude weight'' as the second derivative of the energy. (c) 2000 The American Physical Society
Rahm, Martin; Hoffmann, Roald
2016-03-23
The energy change per electron in a chemical or physical transformation, ΔE/n, may be expressed as Δχ̅ + Δ(VNN + ω)/n, where Δχ̅ is the average electron binding energy, a generalized electronegativity, ΔVNN is the change in nuclear repulsions, and Δω is the change in multielectron interactions in the process considered. The last term can be obtained by the difference from experimental or theoretical estimates of the first terms. Previously obtained consequences of this energy partitioning are extended here to a different analysis of bonding in a great variety of diatomics, including more or less polar ones. Arguments are presented for associating the average change in electron binding energy with covalence, and the change in multielectron interactions with electron transfer, either to, out, or within a molecule. A new descriptor Q, essentially the scaled difference between the Δχ̅ and Δ(VNN + ω)/n terms, when plotted versus the bond energy, separates nicely a wide variety of bonding types, covalent, covalent but more correlated, polar and increasingly ionic, metallogenic, electrostatic, charge-shift bonds, and dispersion interactions. Also, Q itself shows a set of interesting relations with the correlation energy of a bond. PMID:26910496
Théveau, Laure; Schneider, Cédric; Querolle, Olivier; Meerpoel, Lieven; Levacher, Vincent; Hoarau, Christophe
2016-04-01
The construction and subsequent orthogonal functionalization of a hitherto unknown oxazolo[5',4':4,5]pyrano[2,3-b]pyridine are reported. A palladium-catalyzed direct C-H bond functionalization methodology was used to build the tricyclic scaffold as well as to achieve the subsequent C-H bond functionalization at the C-2 position of the oxazole unit with various (hetero)aryl iodides. Remarkably, selective C-H construction and functionalization procedures preserve the chorine atom on the pyridine moiety offering a late-stage substitution site to progress drug design. PMID:26967763
Approach to combined-function magnets via symplectic slicing
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.
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......, the path integral problem can, in principle, be solved exactly by making use of the two-particle pair correlation function (2p-PCF) for the ends of an open polymer, half of the original. This way the exact data for one-dimensional quantum harmonic oscillator are reproduced in a wide range of...... simple self-consistent iteration so as to correctly account for the interparticle interactions. The algorithm is speeded up by taking convolutions with the aid of fast Fourier transforms. We apply this approximate path integral DFT (PI-DFT) method to systems within spherical symmetry: 3D harmonic...
Configuration interaction wave functions: A seniority number approach
International Nuclear Information System (INIS)
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
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.
A hybrid fuzzy MCDM approach to maintenance Quality Function Deployment
Directory of Open Access Journals (Sweden)
Davy George Valavi
2015-01-01
Full Text Available Maintenance Quality Function Deployment (MQFD is a model, which enhances the synergic power of Quality Function Deployment (QFD and Total Productive Maintenance (TPM. One of the crucial and important steps during the implementation of MQFD is the determination of the importance or weightages of the critical factors (CF and sub factors (SF. The CFs and SFs have to be compared precisely for the successful implementation of MQFD. The crisp pair-wise comparison in the conventional Analytical Hierarchy Process (AHP may be insufficient to determine the degree of weightage of CFs and SFs where vagueness and uncetainties are associated. In this paper, a modification of AHP based MQFD by incorporating fuzzy operations is proposed, which can improve the accuracy of determination of the weightages. A case study showing the applicability of this method is illustrated in this paper.
Functional dyspepsia: A new approach from traditional Persian medicine
Mehdi Pasalar; Majid Nimrouzi; Rasool Choopani; Mahmoud Mosaddegh; Mohammad Kamalinejad; Abolali Mohagheghzadeh; Kamran Bagheri Lankarani
2016-01-01
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 medici...
Accounting for Income Distribution Trends : A Density Function Decomposition Approach
Jenkins, Stephen P.; VAN KERM Philippe
2004-01-01
This paper develops methods for decomposing changes in the income distribution using subgroup decompositions of the income density function. Overall changes are related to changes in subgroup shares and changes in subgroup densities, where the latter are broken down further using elementary transformations of individual incomes. These density decompositions are analogous to the widely-used decompositions of inequality indices by population subgroup, except that they summarize multiple feature...
An information theoretic approach to the functional classification of neurons
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...
Recent molecular approaches to understanding astrocyte function in vivo
Fiacco, Todd A.; Cendra Agulhon
2013-01-01
Astrocytes are a predominant glial cell type in the nervous systems, and are becoming recognized as important mediators of normal brain function as well as neurodevelopmental, neurological, and neurodegenerative brain diseases. Although numerous potential mechanisms have been proposed to explain the role of astrocytes in the normal and diseased brain, research into the physiological relevance of these mechanisms in vivo is just beginning. In this review, we will summarize recent developments ...
Promoting return of function in multiple sclerosis: An integrated approach
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...
Functional Neuroimaging Approaches to the Changing Borders of Consciousness
Noirhomme, Quentin; Soddu, Andrea; Vanhaudenhuyse, Audrey; Lehembre, Remy; Bruno, Marie-Aurélie; Gosseries, Olivia; Demertzi, Athina; Maudoux, Audrey; Schnakers, Caroline; Boveroux, Pierre; Boly, Mélanie; Laureys, Steven
2010-01-01
The bedside diagnosis of vegetative and minimally conscious patients is extremely challenging, and prediction of individual long-term outcome remains difficult. State-of the art neuroimaging methods could help disentangle complex cases and offer new prognostic criteria. These methods can be divided into to three categories: First, new anatomical MRI neuroimaging methods, like diffusion tensor imaging (DTI) or spectroscopy, and passive functional imaging methods (looking at the brain’...
Relativistic Wigner Function Approach to Neutrino Propagation in Matter
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...
Relativistic Wigner function approach to neutrino propagation in matter
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.
Robust Benefit Function Transfer: A Bayesian Model Averaging Approach
Roberto Leon-Gonzalez; Riccardo Scarpa
2007-01-01
A Benefit Function Transfer obtains estimates of Willingness-to-Pay (WTP) for the evaluation of a given policy at a site by combining existing information from different study sites. This has the advantage that more efficient estimates are obtained, but it relies on the assumption that the heterogeneity between sites is appropriately captured in the Benefit Transfer model. A more expensive alternative to estimate WTP is to analyse only data from the policy site in question while ignoring info...
On the functional integral approach in quantum statistics. 1. Some approximations
International Nuclear Information System (INIS)
In this paper the susceptibility of a Kondo system in a fairly wide temperature region is calculated in the first harmonic approximation in a functional integral approach. The comparison with that of the renormalization group theory shows that in this region the two results agree quite well. The expansion of the partition function with infinite independent harmonics for the Anderson model is studied. Some symmetry relations are generalized. It is a challenging problem to develop a functional integral approach including diagram analysis, mixed mode effects and some exact relations in the Anderson system proved in the functional integral approach. These topics will be discussed in the next paper. (author). 22 refs, 1 fig
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
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.
Chemical approaches for mimicking logic functions within fluorescent MPT dyes
Institute of Scientific and Technical Information of China (English)
无
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.
On Spectral Approach to Pascal White Noise Functionals
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.
Contribution of DSm Approach to the Belief Function Theory
Czech Academy of Sciences Publication Activity Database
Daniel, Milan
Málaga : University of Malaga, 2008 - (Magdelana, L.; Ojeda-Aciego, M.; Verdegay, J.), s. 417-424 ISBN 978-84-612-3061-7. [IPMU 2008 /12./. Málaga (ES), 22.06.2008-27.06.2008] R&D Projects: GA AV ČR 1ET100300419 Institutional research plan: CEZ:AV0Z10300504 Keywords : belief function * Dempster-Shafer theory * DSm theory * constraints * overlapping elements * exclusive elements * non-separable elements Subject RIV: BA - General Mathematics
Nuclear clustering in the energy density functional approach
International Nuclear Information System (INIS)
Nuclear Energy Density Functionals (EDFs) are a microscopic tool of choice extensively used over the whole chart to successfully describe the properties of atomic nuclei ensuing from their quantum liquid nature. In the last decade, they also have proved their ability to deal with the cluster phenomenon, shedding a new light on its fundamental understanding by treating on an equal footing both quantum liquid and cluster aspects of nuclei. Such a unified microscopic description based on nucleonic degrees of freedom enables to tackle the question pertaining to the origin of the cluster phenomenon and emphasizes intrinsic mechanisms leading to the emergence of clusters in nuclei
Relativistic Wigner Function Approach to Neutrino Propagation in Matter
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.
Nuclear clustering in the energy density functional approach
Energy Technology Data Exchange (ETDEWEB)
Ebran, J.-P., E-mail: jean-paul.ebran@cea.fr [CEA,DAM,DIF, F-91297 Arpajon (France); Khan, E. [Institut de Physique Nucléaire, Université Paris-Sud CEA, IN2P3 CNRS, F-91406 Orsay Cedex (France); Nikšić, T.; Vretenar, D. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia)
2015-10-15
Nuclear Energy Density Functionals (EDFs) are a microscopic tool of choice extensively used over the whole chart to successfully describe the properties of atomic nuclei ensuing from their quantum liquid nature. In the last decade, they also have proved their ability to deal with the cluster phenomenon, shedding a new light on its fundamental understanding by treating on an equal footing both quantum liquid and cluster aspects of nuclei. Such a unified microscopic description based on nucleonic degrees of freedom enables to tackle the question pertaining to the origin of the cluster phenomenon and emphasizes intrinsic mechanisms leading to the emergence of clusters in nuclei.
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.
Solvation force between tethered polyelectrolyte layers. A density functional approach
Directory of Open Access Journals (Sweden)
O. Pizio
2012-10-01
Full Text Available We use a version of the density functional theory to study the solvation force between two plates modified with a tethered layer of chains. The chains are built of tangentially jointed charged spherical segments. The plates are immersed in an electrolyte solution that involves cations, anions and solvent molecules. The latter molecules are modelled as hard spheres. We study the dependence of the solvation force and the structure of chains and of solute molecules on the grafting density, length of chains, architecture of the chains and on concentration of the solute.
Covalent bond orders for non-bonded atoms: The case for carbon-carbon interactions
International Nuclear Information System (INIS)
The Cioslowski-Mixon (CM) covalent bond order and the atoms-in-molecules (AIM) delocalization index can be used to study bonding characteristics between atoms not bonded in the conventional chemical sense. In particular, the bond orders between atoms (AIM basins) with one intervening atom evolve in a predictable manner and are related to the bond orders of conventionally bonded species. The CM approach shows that it is the tails of the incompletely localized orbitals that provide for such interactions. Single, multiple, and resonant bond effects are seen which are physically meaningful and useful as an additional characterization of molecular bonding. The important case of carbon-carbon interactions is studied here.
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.
VISUALIZATION APPROACH TO STRUCTURE-FUNCTION RELATIONSHIP IN BIOLOGICAL MACROMOLECULES
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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
The QCD analysis of xF_3 structure function based on the analytic approach
Sidorov, A. V.; Solovtsova, O. P.
2013-01-01
We apply analytic perturbation theory to the QCD analysis of the xF_3 structure function data of the CCFR collaboration. We use different approaches for the leading order Q^2 evolution of the xF_3 structure function and compare the extracted values of the parameter Lambda_QCD and the shape of the higher twistcontribution. Our consideration is based on the Jacobi polynomial expansion method of the unpolarized structure function. The analysis shows that the analytic approach provides reasonable...
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.
Zhao, Liang; Baslé, Oliver; Li, Chao-Jun
2009-01-01
A copper-catalyzed α-functionalization of glycine derivatives and short peptides with nucleophiles is described. The present method provides ways to introduce functionalities such as aryl, vinyl, alkynyl, or indolyl specifically to the terminal glycine moieties of small peptides, which are normally difficult in peptide modifications. Furthermore, on functionalization, the configurations of other stereocenters in the peptides could be maintained. Because the functionalized peptides could easil...
Electronic structure of disordered graphene with Green's function approach
International Nuclear Information System (INIS)
The Green functions play a big role in the calculation of the local density of states of the carbon nanostructures. We investigate their nature for the variously oriented and disclinated graphene-like surface. Next, we investigate the case of a small perturbation generated by two heptagonal defects and from the character of the local density of states in the border sites of these defects we derive their minimal and maximal distances on the perturbed cylindrical surface. For this purpose, we transform the given surface into a chain using the Haydock recursion method. We will suppose only the nearest-neighbor interactions between the atom orbitals, in other words, the calculations suppose the short-range potential. -- Highlights: ► The Green functions play a big role in the calculation of the local density of states of the carbon nanostructures. ► We investigate their nature for the variously oriented and disclinated graphene-like surface. ► We investigate the case of a small perturbation generated by two heptagonal defects. ► We transform the given surface into a chain using the Haydock recursion method.
Approach to a correct function of stuffing boxes
International Nuclear Information System (INIS)
Stuff boxes are often used to tighten the gaps between valve stems and the housing. The stuffing box packing material is compressed axially to achieve a radial stress value, which is necessary for tightness. Tightness is achieved, if the sealing materials are seated properly and if a sufficient stress value is acting in radial direction during all states of operation. High prestress values are necessary for tightening purposes, lower values are better for the function of the valve. As the seating and the prestressing force is applied axially (using the bolts of a gland), gasket factors must be known, that characterize the deformation behavior and the transmission (relation between radial/axial stress). Furthermore, gasket factors, that characterize the tightening behavior, are necessary. Such gasket factors give the relation between radial stress and leakage of the packing materials. A friction coefficient -- this parameter determines the function of the valve (together with the radial stress) -- is another important gasket factor. Additionally the relaxation of the stuffing box packing material between the assembly and the operating state must be known. In the paper definitions for the most important gasket factors of stuffing box materials are provided. Test procedures and test rigs for the determination of the gasket factors are discussed. Gasket factors, which have been measured with these newly developed test rigs, are related to experiences with real applications. Finally a method for a controlled prestressing of gland packings is described
Defining the neurocircuitry of borderline personality disorder: functional neuroimaging approaches.
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
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.
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
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.
Photochromic supramolecular azopolyimides based on hydrogen bonds
Schab-Balcerzak, Ewa; Flakus, Henryk; Jarczyk-Jedryka, Anna; Konieczkowska, Jolanta; Siwy, Mariola; Bijak, Katarzyna; Sobolewska, Anna; Stumpe, Joachim
2015-09-01
The approach of deriving new photoresponsive active supramolecular azopolymers based on the hydrogen bonds is described. Polymers with imide rings, i.e., poly(esterimide)s and poly(etherimide)s, with phenolic hydroxyl or carboxylic groups were applied as matrixes for the polymer-dye supramolecular systems. Supramolecular films were built on the basis of the hydrogen bonds between the functional groups of the polymers and various azochromophores, that is, 4-phenylazophenol, 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene, 4-[4-(6-hexadecaneoxy)phenylazo]pyridine and 4-(4-hydroxyphenylazo)pyridine. The hydrogen bonding interaction in azo-systems were studied by Fourier transform infrared spectroscopy and for selected assembles by 1H NMR technique. The obtained polyimide azo-assembles were characterized by X-ray diffraction and DSC measurements. H-bonds allow attaching a chromophore to each repeating unit of the polymer, thereby suppressing the macroscopic phase separation except for the systems based on 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene. H-bonds systems were amorphous and revealed glass transition temperatures lower than for the polyimide matrixes (170-260 °C). The photoresponsive behavior of the azo-assemblies was tasted in holographic recording experiment.
An analytic function approach to weak mutually unbiased bases
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.
Intelligent platforms for disease assessment: novel approaches in functional echocardiography.
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
I2/O2-Enabled N-S Bond Formation to Access Functionalized 1,2,3-Thiadiazoles.
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
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.
Estimating Structural Models of Corporate Bond Prices in Indonesian Corporations
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Lenny Suardi
2010-07-01
Full Text Available This paper applies the maximum likelihood (ML approaches to implementing the structural model of corporate bond, as suggested by Li and Wong (2008, in Indonesian corporations. Two structural models, extended Merton and Longstaff & Schwartz (LS models, are used in determining these prices, yields, yield spreads and probabilities of default. ML estimation is used to determine the volatility of firm value. Since firm value is unobserved variable, Duan (1994 suggested that the first step of ML estimation is to derive the likelihood function for equity as the option on the firm value. The second step is to ind parameters such as the drift and volatility of firm value, that maximizing this function. The firm value itself is extracted by equating the pricing formula to the observed equity prices. Equity, total liabilities, bond prices data and the firm's parameters (firm value, volatility of firm value, and default barrier are substituted to extended Merton and LS bond pricing formula in order to valuate the corporate bond.These models are implemented to a sample of 24 bond prices in Indonesian corporation during period of 2001-2005, based on criteria of Eom, Helwege and Huang (2004. The equity and bond prices data were obtained from Indonesia Stock Exchange for firms that issued equity and provided regular financial statement within this period. The result shows that both models, in average, underestimate the bond prices and overestimate the yields and yield spread.
Role of Cell-Cell bond for the viability and the function of vascular smooth muscle cells
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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
Functional dyspepsia: A new approach from traditional Persian medicine
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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.
Astrocytes, Synapses and Brain Function: A Computational Approach
Nadkarni, Suhita
2006-03-01
Modulation of synaptic reliability is one of the leading mechanisms involved in long- term potentiation (LTP) and long-term depression (LTD) and therefore has implications in information processing in the brain. A recently discovered mechanism for modulating synaptic reliability critically involves recruitments of astrocytes - star- shaped cells that outnumber the neurons in most parts of the central nervous system. Astrocytes until recently were thought to be subordinate cells merely participating in supporting neuronal functions. New evidence, however, made available by advances in imaging technology has changed the way we envision the role of these cells in synaptic transmission and as modulator of neuronal excitability. We put forward a novel mathematical framework based on the biophysics of the bidirectional neuron-astrocyte interactions that quantitatively accounts for two distinct experimental manifestation of recruitment of astrocytes in synaptic transmission: a) transformation of a low fidelity synapse transforms into a high fidelity synapse and b) enhanced postsynaptic spontaneous currents when astrocytes are activated. Such a framework is not only useful for modeling neuronal dynamics in a realistic environment but also provides a conceptual basis for interpreting experiments. Based on this modeling framework, we explore the role of astrocytes for neuronal network behavior such as synchrony and correlations and compare with experimental data from cultured networks.
Approaching human performance the functionality-driven Awiwi robot hand
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. ...
Sorption on deformable solids. Density functional theory approach.
Berim, Gersh O; Ruckenstein, Eli
2011-11-17
A modified density functional theory is proposed to describe fluid adsorption and absorption by a solid, the density of which is nonhomogeneous near the interface. The density distribution of the solid is not provided by apriori assumptions, but is obtained via the minimization of an appropriate thermodynamic potential. The theory considers a mixture of two components in a slitlike pore. One of them, the fluid, is in contact with a reservoir containing the same kind of molecules and can be described through a grand canonical ensemble. The other component has strong interactions between its molecules. As a consequence, it forms a solid in the slit which can be treated as a canonical ensemble of a fixed number of molecules. The theory predicts both an intrinsic (in the absence of fluid) change in the solid density near the interface and a solid density variation as the fluid density in the reservoir is changed. In addition, it reveals that the oscillations that occur in the fluid density when the solid density is uniform are damped by the nonuniform solid. The theory provides the amounts of fluid adsorbed as well as absorbed by the solid. PMID:21985615
Functional and aesthetic approach to design of bird feeders
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.
Functional dyspepsia: A new approach from traditional Persian medicine
Pasalar, Mehdi; Nimrouzi, Majid; Choopani, Rasool; Mosaddegh, Mahmoud; Kamalinejad, Mohammad; Mohagheghzadeh, Abdolali; Bagheri Lankarani, Kamran
2016-01-01
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.
Funnel function approach to determine uncertainty: Some advances
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.
Makrlík, Emanuel; Selucký, Pavel; Vaňura, Petr
2012-06-01
From extraction experiments and γ-activity measurements, the exchange extraction constantcorresponding to the general equilibrium Ca2+(aq) + 2HL(nb) CaL2(nb) + 2H+(aq) taking place in the two-phase water-nitrobenzene (L- = anionic ligand based on cobalt bis(dicarbollide) anion with covalently bonded CMPO function; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (Ca2+, 2HL) = 0.0 ± 0.1. Further, the stability constant of the electroneutral complex species CaL2 in water-saturated nitrobenzene was calculated for a temperature of 25 °C : log βnb (CaL2) = 11.0 ± 0.2. PMID:24061262
International Nuclear Information System (INIS)
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2+(aq) + CaL2(nb) ↔ ML2(nb) + Ca2+(aq) taking place in the two-phase water-nitrobenzene system (M2+ = Mg2+, Sr2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Co2+, Ni2+, Mn2+; L- = anionic ligand based on cobalt bis(dicarbollide) anion with covalently bonded CMPO function; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the electroneutral complex species ML2 in water-saturated nitrobenzene were calculated; they were found to increase in the following cation order: Sr2+ 2+, Ni2+ 2+ 2+ 2+, Cd2+ 2+ 2+ 2+ 22+. (author)
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.
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
International Nuclear Information System (INIS)
Two hypotheses for the dissolution of SiO2 in ionic solutions are investigated via ab initio molecular dynamics (AIMD) simulations. The hypotheses are (1) that the presence of ions induces orientations in H2O molecules at the surface, which favor proton transfer to bridging oxygen (BO) atoms, and (2) the presence of ions induces stronger H-bonding between terminal hydroxyl (TH) groups and BO atoms, allowing proton transfer. It is found that the model structures produced by density functional theory simulations do not support the former hypothesis and are more consistent with the latter. (paper)
International Nuclear Information System (INIS)
A straightforward derivation of Landau's collision term within linear response theory using the memory function approach to correlation function is presented. The relation with recent works in nuclear physics on the subject of the damping of collective modes is shown. It is discussed by means of the equations of motion method. In particular, we point out that the second RPA yields results at variance with Landau's expression. Arguments are advanced that the latter is (still) the correct one. (orig.)
Chin, Sai-Kong; Lam, Kai-Tak; Seah, Dawei; Liang, Gengchiau
2012-01-01
We present an efficient approach to study the carrier transport in graphene nanoribbon (GNR) devices using the non-equilibrium Green's function approach (NEGF) based on the Dirac equation calibrated to the tight-binding π-bond model for graphene. The approach has the advantage of the computational efficiency of the Dirac equation and still captures sufficient quantitative details of the bandstructure from the tight-binding π-bond model for graphene. We demonstrate how the exact self-energies ...
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.
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
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.
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.
Finding Global Minima with a Filled Function Approach for Non-Smooth Global Optimization
Directory of Open Access Journals (Sweden)
Ying Zhang
2010-01-01
Full Text Available A filled function approach is proposed for solving a non-smooth unconstrained global optimization problem. First, the definition of filled function in Zhang (2009 for smooth global optimization is extended to non-smooth case and a new one is put forwarded. Then, a novel filled function is proposed for non-smooth the global optimization and a corresponding non-smooth algorithm based on the filled function is designed. At last, a numerical test is made. The computational results demonstrate that the proposed approach is effcient and reliable.
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.
Transcendental Functions and Initial Value Problems: A Different Approach to Calculus II
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.
Olga V. Avseeva; Yuri B. Tebekin
2011-01-01
The article is devoted to the problem of the quality management for multiphase processes on the basis of the probabilistic approach. Method with continuous response functions is offered from the application of the method of Lagrange multipliers.
Directory of Open Access Journals (Sweden)
Yuri B. Tebekin
2011-11-01
Full Text Available The article is devoted to the problem of the quality management for multiphase processes on the basis of the probabilistic approach. Method with continuous response functions is offered from the application of the method of Lagrange multipliers.
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.
Bonding additives - a thermoanalytical approach
Czech Academy of Sciences Publication Activity Database
Kovářová, Jana; Podešva, Jiří
Belgrade: Materials Research Society of Serbia , 2012 - (Uskoković, D.). s. 22 [Annual Conference YUCOMAT 2012 /14./. 03.09.2012-07.09.2012, Herceg Novi] R&D Projects: GA MPO FR-TI2/338 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : thermal analysis * stabilization Subject RIV: CD - Macromolecular Chemistry
Divya, A.; Mathavan, T.; Asath, R. Mohamed; Archana, J.; Hayakawa, Y.; Benial, A. Milton Franklin
2016-05-01
A series of strontium oxide functionalized graphene nanoflakes were designed and their optoelectronic properties were studied for enhanced photocatalytic activity. The efficiency of designed molecules was studied using various parameters such as HOMO-LUMO energy gap, light harvesting efficiency and exciton binding energy. The computed results show that by increasing the degree of functionalization of strontium oxide leads to lowering the band gap of hydrogen terminated graphene nanoflakes. Furthermore, the study explores the role of strontium oxide functionalization in Frontier Molecular Orbitals, ionization potential, electron affinity, exciton binding energy and light harvesting efficiency of designed molecules. The infrared and Raman spectra were simulated for pure and SrO functionalized graphene nanoflakes. The electron rich and electron deficient regions which are favorable for electrophilic and nucleophilic attacks respectively were analyzed using molecular electrostatic potential surface analysis.
Trait-based approaches for understanding microbial biodiversity and ecosystem functioning
SaschaKrause; XavierLe Roux; PascalAlexNiklaus; PeterVanBodegom; JayTLennon; StefanBertilsson; Hans-PeterGrossart; LaurentPhilippot
2014-01-01
In ecology, biodiversity-ecosystem functioning (BEF) research has seen a shift in perspective from taxonomy to function in the last two decades, with successful application of trait-based approaches. This shift offers opportunities for a deeper mechanistic understanding of the role of biodiversity in maintaining multiple ecosystem processes and services. In this paper, we highlight studies that have focused on BEF of microbial communities with an emphasis on integrating trait-based approaches...
Accurate definition of brain regions position through the functional landmark approach.
Thirion, Bertrand; Varoquaux, Gaël; Poline, Jean-Baptiste
2010-01-01
In many application of functional Magnetic Resonance Imaging (fMRI), including clinical or pharmacological studies, the definition of the location of the functional activity between subjects is crucial. While current acquisition and normalization procedures improve the accuracy of the functional signal localization, it is also important to ensure that functional foci detection yields accurate results, and reflects between-subject variability. Here we introduce a fast functional landmark detection procedure, that explicitly models the spatial variability of activation foci in the observed population. We compare this detection approach to standard statistical maps peak extraction procedures: we show that it yields more accurate results on simulations, and more reproducible results on a large cohort of subjects. These results demonstrate that explicit functional landmark modeling approaches are more effective than standard statistical mapping for brain functional focus detection. PMID:20879321
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
International Nuclear Information System (INIS)
Based on the density functional perturbation theory (DFPT), infrared absorption spectra of porous silicon are calculated by using an ordered pore model, in which columns of silicon atoms are removed along the [001] direction and dangling bonds are initially saturated with hydrogen atoms. When these atoms on the pore surface are gradually replaced by oxygen ones, the ab-initio infrared absorption spectra reveal oxygen, hydroxyl, and coupled hydrogen–oxygen vibrational modes. In a parallel way, freestanding porous silicon samples were prepared by using electrochemical etching and they were further thermally oxidized in a dry oxygen ambient. Fourier transform infrared spectroscopy was used to investigate the surface modifications caused by oxygen adsorption. In particular, the predicted hydroxyl and oxygen bound to the silicon pore surface are confirmed. Finally, a global analysis of measured transmittance spectra has been performed by means of a combined DFPT and thin-film optics approach. - Highlights: • The density functional perturbation theory is used to study infrared absorption. • An ordered pore model is used to investigate the oxidation in porous silicon (PSi). • Infrared transmittance spectra of oxidized PSi freestanding samples are measured
Points of convergence between functional and formal approaches to syntactic analysis
DEFF Research Database (Denmark)
Bjerre, Tavs; Engels, Eva; Jørgensen, Henrik;
2008-01-01
AbstractThe paper discusss two different approaches to linguistic theory and their relation to empirical issues in syntactic analysis. The two approaches chosen are probably the two most widespread ones in Scandinavian linguistics, here seen as representing a functional and a formal view respec...
Hot neutron matter from a Self-Consistent Green's Functions approach
Rios, A; Vidaña, I
2008-01-01
A systematic study of the microscopic and thermodynamical properties of pure neutron matter at finite temperature within the Self-Consistent Green's Function approach is performed. The model dependence of these results is analyzed by both comparing the results obtained with two different microscopic interactions, the CD-BONN and the Argonne V18 potentials, and by analyzing the results obtained with other approaches, such as the Brueckner--Hartree--Fock approximation, the variational approach and the virial expansion.
A distance function approach to school-leavers’ efficiency in the school-to-work transition
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 ...
Artificial Neural Network for Transfer Function Placental Development: DCT and DWT Approach
Mohammad Ayache; Mohamad Khalil; Francois Tranquart
2011-01-01
The aim of our study is to propose an approach for transfer function placental development using ultrasound images. This approach is based to the selection of tissues, feature extraction by discrete cosine transform DCT, discrete wavelet transform DWT and classification of different grades of placenta by artificial neural network and especially the multi layer perceptron MLP. The proposed approach is tested for ultrasound images of placenta, resulting in 75% success rate of classification usi...
Pi Bond Orders and Bond Lengths
Herndon, William C.; Parkanyi, Cyril
1976-01-01
Discusses three methods of correlating bond orders and bond lengths in unsaturated hydrocarbons: the Pauling theory, the Huckel molecular orbital technique, and self-consistent-field techniques. (MLH)
Photoinduced hydrogen-bonding dynamics.
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
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
Artificial Neural Network for Transfer Function Placental Development: DCT and DWT Approach
Directory of Open Access Journals (Sweden)
Mohammad Ayache
2011-09-01
Full Text Available The aim of our study is to propose an approach for transfer function placental development using ultrasound images. This approach is based to the selection of tissues, feature extraction by discrete cosine transform DCT, discrete wavelet transform DWT and classification of different grades of placenta by artificial neural network and especially the multi layer perceptron MLP. The proposed approach is tested for ultrasound images of placenta, resulting in 75% success rate of classification using DCT and 92% using DWT. The method based on multi resolution decomposition analysis and on supervised neural network technique MLP, seems a good method to study the transfer function of placental development in ultrasound.
Parand, K; Taghavi, A; 10.1002/mma.1318
2010-01-01
This paper aims to compare rational Chebyshev (RC) and Hermite functions (HF) collocation approach to solve the Volterra's model for population growth of a species within a closed system. This model is a nonlinear integro-differential equation where the integral term represents the effect of toxin. This approach is based on orthogonal functions which will be defined. The collocation method reduces the solution of this problem to the solution of a system of algebraic equations. We also compare these methods with some other numerical results and show that the present approach is applicable for solving nonlinear integro-differential equations.
Huang, Jingzi; Morgan, Glenn
2003-01-01
Investigates use of a functional approach to discourse analysis--knowledge structure analysis, which focuses on meaning, form, and function simultaneously--to evaluate both writing development and content learning. Examined written texts in science, produced by English-as-a-Second-Language students with limited to intermediate English language…
S. De Nicola; Fedele, R.; Man'ko, M. A.; V. I. Man'ko
2005-01-01
New type of tomographic probability distribution, which contains complete information on the density matrix (wave function) related to the Fresnel transform of the complex wave function, is introduced. Relation to symplectic tomographic probability distribution is elucidated. Multimode generalization of the Fresnel tomography is presented. Examples of applications of the present approach are given.
Domestic Bond Market Development
Jonathan A. Batten; Szilagyi, Peter G.
2007-01-01
A two-tiered approach to financial market development aimed at both bank and bond market reform would also be complementary to longer term economic development, provided services could be delivered through efficient financial and legal institutions (Chakraborty and Ray 2006) and there was strong protection for investors and sound fiscal and monetary policy management by government (Burger and Warnock 2006b). Historically, local issuers tend to issue in the major currencies (U.S. dollars, yen,...
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)
A New Approach for Predicting the Variance of Random Decrement Functions
DEFF Research Database (Denmark)
Asmussen, J. C.; Brincker, Rune
technique is that no consistent approach to estimate the variance of the RD functions is known. Only approximate relations are available, which can only be used under special conditions. The variance of teh RD functions contains valuable information about accuracy of the estimates. Furthermore, the variance...... can be used as basis for a decision about how many time lags from the RD funtions should be used in the modal parameter extraction procedure. This paper suggests a new method for estimating the variance of the RD functions. The method is consistent in the sense that the accuracy of the approach is not...
A Two Layer Approach to the Computability and Complexity of Real Functions
DEFF Research Database (Denmark)
Lambov, Branimir Zdravkov
characterizing functions. A similar discrimination is implemented in the presented real number package, which operates on both an approximation layer and a layer which operates on real numbers as complete entities. This approach allows the model to provide correctness and completeness to the established notions......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...
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 ...
Bond graph modeling of centrifugal compression systems
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...
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)
Thomas, Holly N; Thurston, Rebecca C
2016-05-01
A satisfying sex life is an important component of overall well-being, but sexual dysfunction is common, especially in midlife women. The aim of this review is (a) to define sexual function and dysfunction, (b) to present theoretical models of female sexual response, (c) to examine longitudinal studies of how sexual function changes during midlife, and (d) to review treatment options. Four types of female sexual dysfunction are currently recognized: Female Orgasmic Disorder, Female Sexual Interest/Arousal Disorder, Genito-Pelvic Pain/Penetration Disorder, and Substance/Medication-Induced Sexual Dysfunction. However, optimal sexual function transcends the simple absence of dysfunction. A biopsychosocial approach that simultaneously considers physical, psychological, sociocultural, and interpersonal factors is necessary to guide research and clinical care regarding women's sexual function. Most longitudinal studies reveal an association between advancing menopause status and worsening sexual function. Psychosocial variables, such as availability of a partner, relationship quality, and psychological functioning, also play an integral role. Future directions for research should include deepening our understanding of how sexual function changes with aging and developing safe and effective approaches to optimizing women's sexual function with aging. Overall, holistic, biopsychosocial approaches to women's sexual function are necessary to fully understand and treat this key component of midlife women's well-being. PMID:27013288
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
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. PMID:26441717
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.
Quantitative bond energetics in atomic-scale junctions with significant van der Waals character
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.
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.
A parallel approach of COFFEE objective function to multiple sequence alignment
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.
A nonorthogonal state-interaction approach for matrix product state wave functions
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.
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.
International Nuclear Information System (INIS)
In this paper, we do a complete classification of valence-bond crystals (VBCs) on the kagomé lattice based on general arguments of symmetry only and thus identify many new VBCs for different unit cell sizes. For the spin-1/2 Heisenberg antiferromagnet, we study the relative energetics of competing gapless spin liquids (SLs) and VBC phases within the class of Gutzwiller-projected fermionic wave functions using variational Monte Carlo techniques, hence implementing exactly the constraint of one fermion per site. By using a state-of-the-art optimization method, we conclusively show that the U(1) Dirac SL is remarkably stable towards dimerizing into all 6-, 12- and 36-site unit cell VBCs. This stability is also preserved on addition of a next-nearest-neighbor super-exchange coupling of both antiferromagnetic and ferromagnetic (FM) type. However, we find that a 36-site unit cell VBC is stabilized on addition of a very small next-nearest-neighbor FM super-exchange coupling, i.e. |J2| ≈ 0.045, and this VBC is the same in terms of space-group symmetry as that obtained in an effective quantum dimer model study. It breaks reflection symmetry, has a nontrivial flux pattern and is a strong dimerization of the uniform RVB SL. (paper)
International Nuclear Information System (INIS)
First principles calculations of anisotropic elastic constants of titanium boride (TiB) have been performed using the computational implementation of density functional theory (DFT). TiB has orthorhombic crystal structure, thus, nine independent elastic constants need to be determined to completely characterize its polycrystalline elastic behavior as well as elastic anisotropy. TiB, especially in the whisker form, has attracted attention recently as reinforcement in metal matrix composites, wear resistance coatings and has potential as monolithic material due to its high hardness and elastic modulus coupled with its electrically conducting nature. In this study, the elastic constants were determined using the WIEN2K computational implementation of the full-potential-linear-augmented-plane-wave (FLAPW) method and the generalized gradient approximation (GGA). Nine independent elastic distortions of the unit cell were employed to determine the anisotropic elastic constants. Internal atomic relaxations after elastic distortions have been shown to have significant effects on the numerical values of elastic constants. Polycrystalline elastic moduli were determined from the elastic constants and were compared with that extrapolated from experimental data. The nature of chemical bonding and the electronic charge density distribution in TiB have also been explored to explain the high hardness and high stiffness values as well as the nature of elastic anisotropy
A comparison of approaches to estimate the resonance energy
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.
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.
The chemisorptive bond basic concepts
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
Hexacoordinate bonding and aromaticity in silicon phthalocyanine.
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
Mining Functional Modules in Heterogeneous Biological Networks Using Multiplex PageRank Approach.
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
Borowski, Tomasz; Bassan, Arianna; Siegbahn, Per E M
2004-05-17
Density functional calculations using the B3LYP functional have been used to study the reaction mechanism of [Fe(Tp(Ph2))BF] (Tp(Ph2) = hydrotris(3,5-diphenylpyrazol-1-yl)borate; BF = benzoylformate) with dioxygen. This mononuclear non-heme iron(II) complex was recently synthesized, and it proved to be the first biomimetic complex reproducing the dioxygenase activity of alpha-ketoglutarate-dependent enzymes. Moreover, the enthalpy and entropy of activation for this biologically interesting process were derived from kinetic experiments offering a unique possibility for direct comparison of theoretical and experimental data. The results reported here support a mechanism in which oxidative decarboxylation of the keto acid is the rate-limiting step. This oxygen activation process proceeds on the septet potential energy surface through a transition state for a concerted O-O and C-C bond cleavage. In the next step, a high-valent iron-oxo species performs electrophilic attack on the phenyl ring of the Tp(Ph2) ligand leading to an iron(III)-radical sigma-complex. Subsequent proton-coupled electron-transfer yields an iron(II)-phenol intermediate, which can bind dioxygen and reduce it to a superoxide radical. Finally, the protonated superoxide radical leaves the first coordination sphere of the iron(III)-phenolate complex and dismutates to dioxygen and hydrogen peroxide. The calculated activation barrier (enthalpy and entropy) and the overall reaction energy profile agree well with experimental data. A comparison to the enzymatic process, which is suggested to occur on the quintet surface, has been made. PMID:15132638
A Transfer Function Approach to Structural Vibrations Induced by Thermoacoustic Sources
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...
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.
Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality
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.
A functional approach to movement analysis and error identification in sports and physical education
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 functio...
Electronic Structure and Bonding in Complex Biomolecule
Ouyang, Lizhi
2005-03-01
For over a century vitamin B12 and its enzyme cofactor derivates have persistently attracted research efforts for their vital biological role, unique Co-C bonding, rich red-ox chemistry, and recently their candidacies as drug delivery vehicles etc. However, our understanding of this complex metalorganic molecule's efficient enzyme activated catalytic power is still controversial. We have for the first time calculated the electronic structure, Mulliken effective charge and bonding of a whole Vitamin B12 molecule without any structural simplification by first- principles approaches based on density functional theory using structures determined by high resolution X-ray diffraction. A partial density of states analysis shows excellent agreement with X-ray absorption data and has been used successfully to interpret measured optical absorption spectra. Mulliken bonding analysis of B12 and its derivatives reveal noticeable correlations between the two axial ligands which could be exploited by the enzyme to control the catalytic process. Our calculated X-ray near edge structure of B12 and its derivates using Slater's transition state theory are also in good agreement with experiments. The same approach has been applied to other B12 derivatives, ferrocene peptides, and recently DNA molecules.
Approaches to the study of functional activity phagocytic link immune system (review)
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...
Rasmussen, Svend; Damgaard, Martin
2008-01-01
This paper describes a cost function approach to modelling production and resource use at the level of the individual farm firm. The procedure for deriving the supply function using mathematical programming under fairly general condition of a convex input set is shown, and the model is demonstrated. It is suggested that the model is used as the basic building block in agricultural sector models, the advantage being that the technology is modelled as a production frontier providing better oppo...
Consistent descriptions of metal–ligand bonds and spin-crossover in inorganic chemistry
DEFF Research Database (Denmark)
Kepp, Kasper Planeta
2013-01-01
-scale DFT studies of inorganic systems in catalysis and bioinorganic chemistry rely directly on the ability to balance correlation effects in the involved bonds across the s-, p-, and d-blocks. This review concerns recent efforts to describe such bonds accurately and consistently across the s-, p-, and d......-blocks. Physical effects and ingredients in functionals, their systematic errors, and approaches to deal with them are discussed, in order to identify broadly applicable methods for inorganic chemistry....
The effects of hydrogen bonds on metal-mediated O2 activation and related processes
Shook, Ryan L.; Borovik, A. S.
2008-01-01
Hydrogen bonds stabilize and direct chemistry performed by metalloenzymes. With inspiration from enzymes, we will utilize an approach that incorporates intramolecular hydrogen bond donors to determine their effects on the stability and reactivity of metal complexes. Our premise is that control of secondary coordination sphere interactions will promote new function in synthetic metal complexes. Multidentate ligands have been developed that create rigid organic structures around metal ions. The...
Guo, Wei; Zheng, Lv-Yin; Li, Yong-Dong; Wu, Ren-Miao; Chen, Qiang; Yang, Ding-Qiao; Fan, Xiao-Lin
2016-06-10
Discovery of novel topological agents against Oncomelania hupensis snails and cercariae remains a significant challenge in current Schistosomiasis control. A pseudo-ring formed from salicylanilide by an intramolecular hydrogen bond led to the discovery of 3-substituted quinazolinone derivatives which showed a potent molluscicidal and cercaricidal activities. PMID:27017555
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
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.
Skyrme energy-density functional approach to collective modes of excitation in exotic nuclei
International Nuclear Information System (INIS)
Low-frequency collective modes of excitation in neutron-rich nuclei are investigated in the framework of the nuclear energy-density functional method. It is shown that the collective Hamiltonian approach gives the quantitative description of the low-lying states in transitional nuclei with the Skyrme and pairing energy-density functionals as a microscopic input. The inertial functions for large-amplitude vibration and rotation are evaluated by the local normal modes along the axial quadrupole collective coordinate. The time-odd components of the mean fields are fully included in the derived masses
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.
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.
An approach for functional safety improvement of an existing automotive system
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
Analysis of DIS structure functions of the nucleon within truncated Mellin moments approach
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.
Two-dimensional quantum ferromagnet with different spins: a Greens's function approach
International Nuclear Information System (INIS)
The magnetization of a two-dimensional ferromagnetic Heisenberg model, which represents a quantum Hall system at filling factor v=1, is calculated employing Green's function approach. The calculations are discussed in detail for spins S = 1/2, 1 and 3/2. The result for S = 1/2 is compared with recent quantum Monte Carlo simulations (Authors)
Novel Vaccine Approach Achieves “Functional Cure” of AIDS Virus in Monkeys | Poster
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.
On an approach for computing the generating functions of the characters of simple Lie algebras
International Nuclear Information System (INIS)
We describe a general approach to obtain the generating functions of the characters of simple Lie algebras which is based on the theory of the quantum trigonometric Calogero–Sutherland model. We show how the method works in practice by means of a few examples involving some low rank classical algebras. (paper)
Standing wave vs Green's function approach to the Casimir force problem
Schuller, Frédéric; Neumann-Spallart, Michael
2012-01-01
After a short recall of our previous standing wave approach to the Casimir force problem, we consider Lifshitz's temperature Green's function method and its virtues from a physical point of view. Using his formula, specialized for perfectly reflecting mirrors, we present a quantitative discussion of the temperature effect on the attractive force.
THE MODELLING OF MEDICAL INSURANCE WITH USE OF SYSTEM AND STRUCTURAL FUNCTIONAL APPROACH
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.
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
Subvastus and medial parapatellar approaches in TKA: comparison of functional results.
Dutka, Julian; Skowronek, Michal; Sosin, Pawel; Skowronek, Pawel
2011-06-01
The purpose of this study was to compare the clinical results of total knee arthroplasty (TKA) in the early and late postoperative period using subvastus and medial parapatellar approach. A prospective randomized controlled study was conducted in a group of 169 patients (180 TKAs) with 2-year follow-up. Patients were divided into a study group (97 TKAs) with a subvastus approach and a control group (83 TKAs) with a parapatellar approach. Assessment of the results of both operating approaches was based on functional, clinical Knee Society Score, and pain (visual analog scale). Patients in the subvastus group achieved full active extension, better range of motion, and better Knee Society Score results at 12 days, 6 weeks, and 12 weeks earlier than patients in the medial parapatellar group. They also had less pain at 12 days. No statistically significant differences existed between assessed end points in both groups at 24- and 52-weeks, and 24-months postoperatively. The subvastus approach has given patients better early clinical results; however, at longer follow-up, both groups had similar outcomes. The potential benefits of the subvastus approach are: protection of the extensor mechanism from damage, less risk of damaging the blood supply to the patella, earlier clinical recovery, and less pain in the early postoperative period. The subvastus approach is an alternative to the standard medial parapatellar approach in TKA. It can be used with equally good results, especially taking into consideration positive clinical aspects in the early postoperative period. PMID:21667899
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
A new approach to wall modeling in LES of incompressible flow via function enrichment
Krank, Benjamin
2015-01-01
A novel approach to wall modeling for the incompressible Navier-Stokes equations including flows of moderate and large Reynolds numbers is presented. The basic idea is that a problem-tailored function space allows prediction of turbulent boundary layer gradients with very coarse meshes. The proposed function space consists of a standard polynomial function space plus an enrichment, which is constructed using Spalding's law-of-the-wall. The enrichment function is not enforced but "allowed" in a consistent way and the overall methodology is much more general and also enables other enrichment functions. The proposed method is closely related to detached-eddy simulation as near-wall turbulence is modeled statistically and large eddies are resolved in the bulk flow. Interpreted in terms of a three-scale separation within the variational multiscale method, the standard scale resolves large eddies and the enrichment scale represents boundary layer turbulence in an averaged sense. The potential of the scheme is shown...
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...
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.
A Functional Approach to Compiling a Specialized English–Slovene Dictionary of Green Energy Terms
Directory of Open Access Journals (Sweden)
Laura Mrhar
2013-12-01
Full Text Available The functional approach to lexicography argues that dictionaries must provide their users with concrete types of information, presented in a manner that suits their needs. To achieve this, the process of compiling specialized dictionaries must be improved. This paper examines the revision of a specialized English–Slovene Dictionary of Green Energy Terms, with particular emphasis on the functional approach to building specialized dictionaries. As the potential users of the unrevised dictionary differ from those of the revised version, this paper aims to show how the profile of the intended user affects the structure of the actual dictionary entry, as well as the dictionary’s main functions. The main objective of the paper is therefore to put forward a sound theoretical foundation for the improved construction of LSP dictionaries, so that they will truly serve as a helpful tool in solving those problems that normally occur in LSP communication.
A modular approach to introduce function into single-chain polymeric nanoparticles.
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
Fast approach to infrared image restoration based on shrinkage functions calibration
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.
Delocalized π state between molecules through a surface confined pseudodihydrogen bond.
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