Teaching Molecular Symmetry of Dihedral Point Groups by Drawing Useful 2D Projections

Science.gov (United States)

Chen, Lan; Sun, Hongwei; Lai, Chengming

2015-01-01

There are two main difficulties in studying molecular symmetry of dihedral point groups. One is locating the C[subscript 2] axes perpendicular to the C[subscript n] axis, while the other is finding the s[subscript]d planes which pass through the C[subscript n] axis and bisect the angles formed by adjacent C[subscript 2] axes. In this paper, a…

CACA-TOCSY with alternate 13C–12C labeling: a 13Cα direct detection experiment for mainchain resonance assignment, dihedral angle information, and amino acid type identification

Science.gov (United States)

Takeuchi, Koh; Frueh, Dominique P.; Sun, Zhen-Yu J.; Hiller, Sebastian

2010-01-01

We present a 13C direct detection CACA-TOCSY experiment for samples with alternate 13C–12C labeling. It provides inter-residue correlations between 13Cα resonances of residue i and adjacent Cαs at positions i − 1 and i + 1. Furthermore, longer mixing times yield correlations to Cα nuclei separated by more than one residue. The experiment also provides Cα-to-sidechain correlations, some amino acid type identifications and estimates for ψ dihedral angles. The power of the experiment derives from the alternate 13C–12C labeling with [1,3-13C] glycerol or [2-13C] glycerol, which allows utilizing the small scalar 3JCC couplings that are masked by strong 1JCC couplings in uniformly 13C labeled samples. PMID:20383561

Torsion angle dependence of the rectifying performance in molecular device with asymmetrical anchoring groups

International Nuclear Information System (INIS)

Wang, L.H.; Guo, Y.; Tian, C.F.; Song, X.P.; Ding, B.J.

2010-01-01

Using first-principles density functional theory and nonequilibrium Green's function formalism, we investigate the effect of torsion angle on the rectifying characteristics of 4'-thiolate-biphenyl-4-dithiocarboxylate sandwiched between two Au(111) electrodes. The results show that the torsion angle has an evident influence on rectifying performance of such devices. By increasing the dihedral angle between two phenyl rings, namely changing the magnitude of the intermolecular coupling effect, a different rectifying behavior can be observed in these systems. Our findings highlight that the rectifying characteristics are intimately related to dihedral angles and can provide fundamental guidelines for the design of functional molecular devices.

CACA-TOCSY with alternate 13C-12C labeling: a 13Cα direct detection experiment for mainchain resonance assignment, dihedral angle information, and amino acid type identification

International Nuclear Information System (INIS)

Takeuchi, Koh; Frueh, Dominique P.; Sun, Zhen-Yu J.; Hiller, Sebastian; Wagner, Gerhard

2010-01-01

We present a 13 C direct detection CACA-TOCSY experiment for samples with alternate 13 C- 12 C labeling. It provides inter-residue correlations between 13 C α resonances of residue i and adjacent C α s at positions i - 1 and i + 1. Furthermore, longer mixing times yield correlations to C α nuclei separated by more than one residue. The experiment also provides C α -to-sidechain correlations, some amino acid type identifications and estimates for ψ dihedral angles. The power of the experiment derives from the alternate 13 C- 12 C labeling with [1,3- 13 C] glycerol or [2- 13 C] glycerol, which allows utilizing the small scalar 3 J CC couplings that are masked by strong 1 J CC couplings in uniformly 13 C labeled samples.

CACA-TOCSY with alternate 13C-12C labeling: a 13Calpha direct detection experiment for mainchain resonance assignment, dihedral angle information, and amino acid type identification.

Science.gov (United States)

Takeuchi, Koh; Frueh, Dominique P; Sun, Zhen-Yu J; Hiller, Sebastian; Wagner, Gerhard

2010-05-01

We present a (13)C direct detection CACA-TOCSY experiment for samples with alternate (13)C-(12)C labeling. It provides inter-residue correlations between (13)C(alpha) resonances of residue i and adjacent C(alpha)s at positions i - 1 and i + 1. Furthermore, longer mixing times yield correlations to C(alpha) nuclei separated by more than one residue. The experiment also provides C(alpha)-to-sidechain correlations, some amino acid type identifications and estimates for psi dihedral angles. The power of the experiment derives from the alternate (13)C-(12)C labeling with [1,3-(13)C] glycerol or [2-(13)C] glycerol, which allows utilizing the small scalar (3)J(CC) couplings that are masked by strong (1)J(CC) couplings in uniformly (13)C labeled samples.

A general method for the derivation of the functional forms of the effective energy terms in coarse-grained energy functions of polymers. II. Backbone-local potentials of coarse-grained O 1 →4 -bonded polyglucose chains

Science.gov (United States)

Lubecka, Emilia A.; Liwo, Adam

2017-09-01

Based on the theory of the construction of coarse-grained force fields for polymer chains described in our recent work [A. K. Sieradzan et al., J. Chem. Phys. 146, 124106 (2017)], in this work effective coarse-grained potentials, to be used in the SUGRES-1P model of polysaccharides that is being developed in our laboratory, have been determined for the O ⋯O ⋯O virtual-bond angles (θ ) and for the dihedral angles for rotation about the O ⋯O virtual bonds (γ ) of 1 → 4 -linked glucosyl polysaccharides, for all possible combinations of [α ,β ]-[d,l]-glucose. The potentials of mean force corresponding to the virtual-bond angles and the virtual-bond dihedral angles were calculated from the free-energy surfaces of [α ,β ]-[d,l]-glucose pairs, determined by umbrella-sampling molecular-dynamics simulations with the AMBER12 force field, or combinations of the surfaces of two pairs sharing the overlapping residue, respectively, by integrating the respective Boltzmann factor over the dihedral angles λ for the rotation of the sugar units about the O ⋯O virtual bonds. Analytical expressions were subsequently fitted to the potentials of mean force. The virtual-bond-torsional potentials depend on both virtual-bond-dihedral angles and virtual-bond angles. The virtual-bond-angle potentials contain a single minimum at about θ =14 0° for all pairs except β -d-[α ,β ] -l-glucose, where the global minimum is shifted to θ =150° and a secondary minimum appears at θ =90°. The torsional potentials favor small negative γ angles for the α -d-glucose and extended negative angles γ for the β -d-glucose chains, as observed in the experimental structures of starch and cellulose, respectively. It was also demonstrated that the approximate expression derived based on Kubo's cluster-cumulant theory, whose coefficients depend on the identity of the disugar units comprising a trisugar unit that defines a torsional potential, fits simultaneously all

Automorphic Lie algebras with dihedral symmetry

International Nuclear Information System (INIS)

Knibbeler, V; Lombardo, S; A Sanders, J

2014-01-01

The concept of automorphic Lie algebras arises in the context of reduction groups introduced in the early 1980s in the field of integrable systems. automorphic Lie algebras are obtained by imposing a discrete group symmetry on a current algebra of Krichever–Novikov type. Past work shows remarkable uniformity between algebras associated to different reduction groups. For example, if the base Lie algebra is sl 2 (C) and the poles of the automorphic Lie algebra are restricted to an exceptional orbit of the symmetry group, changing the reduction group does not affect the Lie algebra structure. In this research we fix the reduction group to be the dihedral group and vary the orbit of poles as well as the group action on the base Lie algebra. We find a uniform description of automorphic Lie algebras with dihedral symmetry, valid for poles at exceptional and generic orbits. (paper)

CACA-TOCSY with alternate {sup 13}C-{sup 12}C labeling: a {sup 13}C{sup {alpha}} direct detection experiment for mainchain resonance assignment, dihedral angle information, and amino acid type identification

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, Koh [National Institute of Advanced Industrial Science and Technology (AIST), Biomedicinal Information Research Center (BIRC) (Japan); Frueh, Dominique P.; Sun, Zhen-Yu J.; Hiller, Sebastian; Wagner, Gerhard, E-mail: gerhard_wagner@hms.harvard.ed [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States)

2010-05-15

We present a {sup 13}C direct detection CACA-TOCSY experiment for samples with alternate {sup 13}C-{sup 12}C labeling. It provides inter-residue correlations between {sup 13}C{sup {alpha}} resonances of residue i and adjacent C{sup {alpha}s} at positions i - 1 and i + 1. Furthermore, longer mixing times yield correlations to C{sup {alpha}} nuclei separated by more than one residue. The experiment also provides C{sup {alpha}}-to-side chain correlations, some amino acid type identifications and estimates for {psi} dihedral angles. The power of the experiment derives from the alternate {sup 13}C-{sup 12}C labeling with [1,3-{sup 13}C] glycerol or [2-{sup 13}C] glycerol, which allows utilizing the small scalar {sup 3}J{sub CC} couplings that are masked by strong {sup 1}J{sub CC} couplings in uniformly {sup 13}C labeled samples.

Integral pentavalent Cayley graphs on abelian or dihedral groups

Indian Academy of Sciences (India)

MOHSEN GHASEMI

ghasemi@urmia.ac.ir. MS received 8 July 2015; revised 10 July 2016. Abstract. A graph is called integral, if all of its eigenvalues are integers. In this paper, we give some results about integral pentavalent Cayley graphs on abelian or dihedral.

Registration of Images with N-fold Dihedral Blur

Czech Academy of Sciences Publication Activity Database

Pedone, M.; Flusser, Jan; Heikkila, J.

2015-01-01

Roč. 24, č. 3 (2015), s. 1036-1045 ISSN 1057-7149 R&D Projects: GA ČR GA13-29225S; GA ČR GA15-16928S Institutional support: RVO:67985556 Keywords : Image registration * blurred images * N-fold rotational symmetry * dihedral symmetry * phase correlation Subject RIV: JD - Computer Applications, Robotics Impact factor: 3.735, year: 2015 http://library.utia.cas.cz/separaty/2015/ZOI/flusser-0441247.pdf

Assessing protein conformational sampling methods based on bivariate lag-distributions of backbone angles

KAUST Repository

Maadooliat, Mehdi; Gao, Xin; Huang, Jianhua Z.

2012-01-01

Despite considerable progress in the past decades, protein structure prediction remains one of the major unsolved problems in computational biology. Angular-sampling-based methods have been extensively studied recently due to their ability to capture the continuous conformational space of protein structures. The literature has focused on using a variety of parametric models of the sequential dependencies between angle pairs along the protein chains. In this article, we present a thorough review of angular-sampling-based methods by assessing three main questions: What is the best distribution type to model the protein angles? What is a reasonable number of components in a mixture model that should be considered to accurately parameterize the joint distribution of the angles? and What is the order of the local sequence-structure dependency that should be considered by a prediction method? We assess the model fits for different methods using bivariate lag-distributions of the dihedral/planar angles. Moreover, the main information across the lags can be extracted using a technique called Lag singular value decomposition (LagSVD), which considers the joint distribution of the dihedral/planar angles over different lags using a nonparametric approach and monitors the behavior of the lag-distribution of the angles using singular value decomposition. As a result, we developed graphical tools and numerical measurements to compare and evaluate the performance of different model fits. Furthermore, we developed a web-tool (http://www.stat.tamu. edu/~madoliat/LagSVD) that can be used to produce informative animations. © The Author 2012. Published by Oxford University Press.

Assessing protein conformational sampling methods based on bivariate lag-distributions of backbone angles

KAUST Repository

Maadooliat, Mehdi

2012-08-27

Despite considerable progress in the past decades, protein structure prediction remains one of the major unsolved problems in computational biology. Angular-sampling-based methods have been extensively studied recently due to their ability to capture the continuous conformational space of protein structures. The literature has focused on using a variety of parametric models of the sequential dependencies between angle pairs along the protein chains. In this article, we present a thorough review of angular-sampling-based methods by assessing three main questions: What is the best distribution type to model the protein angles? What is a reasonable number of components in a mixture model that should be considered to accurately parameterize the joint distribution of the angles? and What is the order of the local sequence-structure dependency that should be considered by a prediction method? We assess the model fits for different methods using bivariate lag-distributions of the dihedral/planar angles. Moreover, the main information across the lags can be extracted using a technique called Lag singular value decomposition (LagSVD), which considers the joint distribution of the dihedral/planar angles over different lags using a nonparametric approach and monitors the behavior of the lag-distribution of the angles using singular value decomposition. As a result, we developed graphical tools and numerical measurements to compare and evaluate the performance of different model fits. Furthermore, we developed a web-tool (http://www.stat.tamu. edu/~madoliat/LagSVD) that can be used to produce informative animations. © The Author 2012. Published by Oxford University Press.

Angle-resolved effective potentials for disk-shaped molecules

Energy Technology Data Exchange (ETDEWEB)

Heinemann, Thomas, E-mail: thomas.heinemann@tu-berlin.de; Klapp, Sabine H. L., E-mail: klapp@physik.tu-berlin.de [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Palczynski, Karol, E-mail: karol.palczynski@helmholtz-berlin.de; Dzubiella, Joachim, E-mail: joachim.dzubiella@helmholtz-berlin.de [Institut für Physik, Humboldt Universität zu Berlin, Newtonstraße 15, 12489 Berlin (Germany); Helmholtz Zentrum Berlin (HZB), Institute of Soft Matter and Functional Materials, Hahn-Meitner Platz 1, 14109 Berlin (Germany)

2014-12-07

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

Overcoming potential energy distortions in constrained internal coordinate molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Kandel, Saugat; Salomon-Ferrer, Romelia; Larsen, Adrien B.; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States); Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2016-01-28

The Internal Coordinate Molecular Dynamics (ICMD) method is an attractive molecular dynamics (MD) method for studying the dynamics of bonded systems such as proteins and polymers. It offers a simple venue for coarsening the dynamics model of a system at multiple hierarchical levels. For example, large scale protein dynamics can be studied using torsional dynamics, where large domains or helical structures can be treated as rigid bodies and the loops connecting them as flexible torsions. ICMD with such a dynamic model of the protein, combined with enhanced conformational sampling method such as temperature replica exchange, allows the sampling of large scale domain motion involving high energy barrier transitions. Once these large scale conformational transitions are sampled, all-torsion, or even all-atom, MD simulations can be carried out for the low energy conformations sampled via coarse grained ICMD to calculate the energetics of distinct conformations. Such hierarchical MD simulations can be carried out with standard all-atom forcefields without the need for compromising on the accuracy of the forces. Using constraints to treat bond lengths and bond angles as rigid can, however, distort the potential energy landscape of the system and reduce the number of dihedral transitions as well as conformational sampling. We present here a two-part solution to overcome such distortions of the potential energy landscape with ICMD models. To alleviate the intrinsic distortion that stems from the reduced phase space in torsional MD, we use the Fixman compensating potential. To additionally alleviate the extrinsic distortion that arises from the coupling between the dihedral angles and bond angles within a force field, we propose a hybrid ICMD method that allows the selective relaxing of bond angles. This hybrid ICMD method bridges the gap between all-atom MD and torsional MD. We demonstrate with examples that these methods together offer a solution to eliminate the potential

Conformational differences between the methoxy groups of QA and QB site ubisemiquinones in bacterial reaction centers: a key role for methoxy group orientation in modulating ubiquinone redox potential.

Science.gov (United States)

Taguchi, Alexander T; O'Malley, Patrick J; Wraight, Colin A; Dikanov, Sergei A

2013-07-09

Ubiquinone is an almost universal, membrane-associated redox mediator. Its ability to accept either one or two electrons allows it to function in critical roles in biological electron transport. The redox properties of ubiquinone in vivo are determined by its environment in the binding sites of proteins and by the dihedral angle of each methoxy group relative to the ring plane. This is an attribute unique to ubiquinone among natural quinones and could account for its widespread function with many different redox complexes. In this work, we use the photosynthetic reaction center as a model system for understanding the role of methoxy conformations in determining the redox potential of the ubiquinone/semiquinone couple. Despite the abundance of X-ray crystal structures for the reaction center, quinone site resolution has thus far been too low to provide a reliable measure of the methoxy dihedral angles of the primary and secondary quinones, QA and QB. We performed 2D ESEEM (HYSCORE) on isolated reaction centers with ubiquinones (13)C-labeled at the headgroup methyl and methoxy substituents, and have measured the (13)C isotropic and anisotropic components of the hyperfine tensors. Hyperfine couplings were compared to those derived by DFT calculations as a function of methoxy torsional angle allowing estimation of the methoxy dihedral angles for the semiquinones in the QA and QB sites. Based on this analysis, the orientation of the 2-methoxy groups are distinct in the two sites, with QB more out of plane by 20-25°. This corresponds to an ≈50 meV larger electron affinity for the QB quinone, indicating a substantial contribution to the experimental difference in redox potentials (60-75 mV) of the two quinones. The methods developed here can be readily extended to ubiquinone-binding sites in other protein complexes.

Fixman compensating potential for general branched molecules

Energy Technology Data Exchange (ETDEWEB)

Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States)

2013-12-28

The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules.

Novel concept of enzyme selective nicotinamide adenine dinucleotide (NAD)-modified inhibitors based on enzyme taxonomy from the diphosphate conformation of NAD.

Science.gov (United States)

Fujii, Mikio; Kitagawa, Yasuyuki; Iida, Shui; Kato, Keisuke; Ono, Machiko

2015-11-15

The dihedral angle θ of the diphosphate part of NAD(P) were investigated to distinguish the differences in the binding-conformation of NAD(P) to enzymes and to create an enzyme taxonomy. Furthermore, new inhibitors with fixed dihedral angles showed that enzymes could recognize the differences in the dihedral angle θ. We suggest the taxonomy and the dihedral angle θ are important values for chemists to consider when designing inhibitors and drugs that target enzymes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Freeman-Durden Decomposition with Oriented Dihedral Scattering

Directory of Open Access Journals (Sweden)

Yan Jian

2014-10-01

Full Text Available In this paper, when the azimuth direction of polarimetric Synthetic Aperature Radars (SAR differs from the planting direction of crops, the double bounce of the incident electromagnetic waves from the terrain surface to the growing crops is investigated and compared with the normal double bounce. Oriented dihedral scattering model is developed to explain the investigated double bounce and is introduced into the Freeman-Durden decomposition. The decomposition algorithm corresponding to the improved decomposition is then proposed. The airborne polarimetric SAR data for agricultural land covering two flight tracks are chosen to validate the algorithm; the decomposition results show that for agricultural vegetated land, the improved Freeman-Durden decomposition has the advantage of increasing the decomposition coherency among the polarimetric SAR data along the different flight tracks.

Modeling Bottom-Up Visual Attention Using Dihedral Group D4 §

Directory of Open Access Journals (Sweden)

Puneet Sharma

2016-08-01

Full Text Available In this paper, first, we briefly describe the dihedral group D 4 that serves as the basis for calculating saliency in our proposed model. Second, our saliency model makes two major changes in a latest state-of-the-art model known as group-based asymmetry. First, based on the properties of the dihedral group D 4 , we simplify the asymmetry calculations associated with the measurement of saliency. This results is an algorithm that reduces the number of calculations by at least half that makes it the fastest among the six best algorithms used in this research article. Second, in order to maximize the information across different chromatic and multi-resolution features, the color image space is de-correlated. We evaluate our algorithm against 10 state-of-the-art saliency models. Our results show that by using optimal parameters for a given dataset, our proposed model can outperform the best saliency algorithm in the literature. However, as the differences among the (few best saliency models are small, we would like to suggest that our proposed model is among the best and the fastest among the best. Finally, as a part of future work, we suggest that our proposed approach on saliency can be extended to include three-dimensional image data.

From lattice BF gauge theory to area-angle Regge calculus

International Nuclear Information System (INIS)

Bonzom, Valentin

2009-01-01

We consider Riemannian 4D BF lattice gauge theory, on a triangulation of spacetime. Introducing the simplicity constraints which turn BF theory into simplicial gravity, some geometric quantities of Regge calculus, areas, and 3D and 4D dihedral angles, are identified. The parallel transport conditions are taken care of to ensure a consistent gluing of simplices. We show that these gluing relations, together with the simplicity constraints, contain the constraints of area-angle Regge calculus in a simple way, via the group structure of the underlying BF gauge theory. This provides a precise road from constrained BF theory to area-angle Regge calculus. Doing so, a framework combining variables of lattice BF theory and Regge calculus is built. The action takes a form a la Regge and includes the contribution of the Immirzi parameter. In the absence of simplicity constraints, the standard spin foam model for BF theory is recovered. Insertions of local observables are investigated, leading to Casimir insertions for areas and reproducing for 3D angles known results obtained through angle operators on spin networks. The present formulation is argued to be suitable for deriving spin foam models from discrete path integrals and to unravel their geometric content.

Deep learning methods for protein torsion angle prediction.

Science.gov (United States)

Li, Haiou; Hou, Jie; Adhikari, Badri; Lyu, Qiang; Cheng, Jianlin

2017-09-18

Deep learning is one of the most powerful machine learning methods that has achieved the state-of-the-art performance in many domains. Since deep learning was introduced to the field of bioinformatics in 2012, it has achieved success in a number of areas such as protein residue-residue contact prediction, secondary structure prediction, and fold recognition. In this work, we developed deep learning methods to improve the prediction of torsion (dihedral) angles of proteins. We design four different deep learning architectures to predict protein torsion angles. The architectures including deep neural network (DNN) and deep restricted Boltzmann machine (DRBN), deep recurrent neural network (DRNN) and deep recurrent restricted Boltzmann machine (DReRBM) since the protein torsion angle prediction is a sequence related problem. In addition to existing protein features, two new features (predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments) are used as input to each of the four deep learning architectures to predict phi and psi angles of protein backbone. The mean absolute error (MAE) of phi and psi angles predicted by DRNN, DReRBM, DRBM and DNN is about 20-21° and 29-30° on an independent dataset. The MAE of phi angle is comparable to the existing methods, but the MAE of psi angle is 29°, 2° lower than the existing methods. On the latest CASP12 targets, our methods also achieved the performance better than or comparable to a state-of-the art method. Our experiment demonstrates that deep learning is a valuable method for predicting protein torsion angles. The deep recurrent network architecture performs slightly better than deep feed-forward architecture, and the predicted residue contact number and the error distribution of torsion angles extracted from sequence fragments are useful features for improving prediction accuracy.

A study of the apsidal angle and a proof of monotonicity in the logarithmic potential case

NARCIS (Netherlands)

Castelli, Roberto

2014-01-01

This paper concerns the behaviour of the apsidal angle for orbits of central force system with homogeneous potential of degree -2 ≤ α ≤ 1 and logarithmic potential. We derive a formula for the apsidal angle as a fixed end-points integral and we study the derivative of the apsidal angle with respect

Infrared spectra of cyanoacetaldehyde (NCCH2CHO): a potential prebiotic compound of astrochemical interest.

Science.gov (United States)

Benidar, Abdessamad; Georges, Robert; Guillemin, Jean-Claude; Mó, Otilia; Yáñez, Manuel

2013-08-26

Cyanoacetaldehyde (NC-CH2CH=O) and its isomer, cyanovinylalcohol (NC-CH=CH-OH), as possible components of the interstellar medium, comets, or planetary atmospheres, exist in equilibrium in the gas phase, although the latter compound is very much in the minority (2%). The recording and analysis of the gas-phase infrared spectrum of the former compound within the 4000-500 cm(-1) spectroscopic range and the potential presence of the latter isomer, which could be vital for their detection in these media, are reported. CCSD(T) and G4 high-level ab initio methods, as well as density functional theory calculations, predict the existence of two stable rotamers of cyanoacetaldehyde. The global minimum has a structure with an unusual O-C-C-C dihedral angle (150°) that falls between the antiperiplanar (180°) and anticlinal forms (120°). The second rotamer, which is about 4.0 kJ mol(-1) less stable in terms of free energy, has a planar structure that corresponds to the synperiplanar form (O-C-C-C dihedral angle: 0°). The absorption vibrational bands of the two aldehyde rotamers that are present in the mixture lead to a spectrum with a very complex structure in the region of deformation movements, in which several low-intensity bands overlap. A complete and unambiguous assignment of the experimental spectrum has been achieved by using the calculated harmonic and anharmonic vibrational frequencies. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Relation between photochromic properties and molecular structures in salicylideneaniline crystals.

Science.gov (United States)

Johmoto, Kohei; Ishida, Takashi; Sekine, Akiko; Uekusa, Hidehiro; Ohashi, Yuji

2012-06-01

The crystal structures of the salicylideneaniline derivatives N-salicylidene-4-tert-butyl-aniline (1), N-3,5-di-tert-butyl-salicylidene-3-methoxyaniline (2), N-3,5-di-tert-butyl-salicylidene-3-bromoaniline (3), N-3,5-di-tert-butyl-salicylidene-3-chloroaniline (4), N-3,5-di-tert-butyl-salicylidene-4-bromoaniline (5), N-3,5-di-tert-butyl-salicylidene-aniline (6), N-3,5-di-tert-butyl-salicylidene-4-carboxyaniline (7) and N-salicylidene-2-chloroaniline (8) were analyzed by X-ray diffraction analysis at ambient temperature to investigate the relationship between their photochromic properties and molecular structures. A clear correlation between photochromism and the dihedral angle of the two benzene rings in the salicylideneaniline derivatives was observed. Crystals with dihedral angles less than 20° were non-photochromic, whereas those with dihedral angles greater than 30° were photochromic. Crystals with dihedral angles between 20 and 30° could be either photochromic or non-photochromic. Inhibition of the pedal motion by intra- or intermolecular steric hindrance, however, can result in non-photochromic behaviour even if the dihedral angle is larger than 30°.

A new hydrocarbon empirical potential in angle bending calculation for the molecular dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Ping, Tan Ai; Hoe, Yeak Su [Department of Mathematical Sciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Johor Darul Takzim (Malaysia)

2014-07-10

Typically, short range potential only depends on neighbouring atoms and its parameters function can be categorized into bond stretching, angle bending and bond rotation potential. In this paper, we present our work called Angle Bending (AB) potential, whereas AB potential is the extension of our previous work namely Bond Stretching (BS) potential. Basically, potential will tend to zero after truncated region, potential in specific region can be represented by different piecewise polynomial. We proposed the AB piecewise potential which is possible to solve a system involving three atoms. AB potential able to handle the potential of covalent bonds for three atoms as well as two atoms cases due to its degeneracy properties. Continuity for the piecewise polynomial has been enforced by coupling with penalty methods. There are still plenty of improvement spaces for this AB potential. The improvement for three atoms AB potential will be studied and further modified into torsional potential which are the ongoing current research.

Flight mechanics of a tailless articulated wing aircraft

International Nuclear Information System (INIS)

Paranjape, Aditya A; Chung, Soon-Jo; Selig, Michael S

2011-01-01

This paper investigates the flight mechanics of a micro aerial vehicle without a vertical tail in an effort to reverse-engineer the agility of avian flight. The key to stability and control of such a tailless aircraft lies in the ability to control the incidence angles and dihedral angles of both wings independently. The dihedral angles can be varied symmetrically on both wings to control aircraft speed independently of the angle of attack and flight path angle, while asymmetric dihedral can be used to control yaw in the absence of a vertical stabilizer. It is shown that wing dihedral angles alone can effectively regulate sideslip during rapid turns and generate a wide range of equilibrium turn rates while maintaining a constant flight speed and regulating sideslip. Numerical continuation and bifurcation analysis are used to compute trim states and assess their stability. This paper lays the foundation for design and stability analysis of a flapping wing aircraft that can switch rapidly from flapping to gliding flight for agile manoeuvring in a constrained environment.

Flight mechanics of a tailless articulated wing aircraft

Energy Technology Data Exchange (ETDEWEB)

Paranjape, Aditya A; Chung, Soon-Jo; Selig, Michael S, E-mail: sjchung@illinois.edu [Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)

2011-06-15

This paper investigates the flight mechanics of a micro aerial vehicle without a vertical tail in an effort to reverse-engineer the agility of avian flight. The key to stability and control of such a tailless aircraft lies in the ability to control the incidence angles and dihedral angles of both wings independently. The dihedral angles can be varied symmetrically on both wings to control aircraft speed independently of the angle of attack and flight path angle, while asymmetric dihedral can be used to control yaw in the absence of a vertical stabilizer. It is shown that wing dihedral angles alone can effectively regulate sideslip during rapid turns and generate a wide range of equilibrium turn rates while maintaining a constant flight speed and regulating sideslip. Numerical continuation and bifurcation analysis are used to compute trim states and assess their stability. This paper lays the foundation for design and stability analysis of a flapping wing aircraft that can switch rapidly from flapping to gliding flight for agile manoeuvring in a constrained environment.

Influence of visual angle on pattern reversal visual evoked potentials

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Ruchi Kothari

2014-01-01

Full Text Available Purpose: The aim of this study was to find whether the visual evoked potential (VEP latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs. Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II. The statistical analysis was done by One Way Analysis of Variance (ANOVA using EPI INFO 6. Results: In Group I, the maximum (max. P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes. Conclusion: Altering the size of stimulus (visual angle has an effect on the PRVEP parameters. Our study found that the 120

On some homological functors of Bieberbach group of dimension four with dihedral point group of order eight

Science.gov (United States)

Mohammad, Siti Afiqah; Ali, Nor Muhainiah Mohd; Sarmin, Nor Haniza; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah

2014-06-01

A Bieberbach group is a torsion free crystallographic group, which is an extension of a free abelian group of finite rank by a finite point group, while homological functors of a group include nonabelian tensor square, exterior square and Schur Multiplier. In this paper, some homological functors of a Bieberbach group of dimension four with dihedral point group of order eight are computed.

Classification Formula and Generation Algorithm of Cycle Decomposition Expression for Dihedral Groups

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Dakun Zhang

2013-01-01

Full Text Available The necessary of classification research on common formula of group (dihedral group cycle decomposition expression is illustrated. It includes the reflection and rotation conversion, which derived six common formulae on cycle decomposition expressions of group; it designed the generation algorithm on the cycle decomposition expressions of group, which is based on the method of replacement conversion and the classification formula; algorithm analysis and the results of the process show that the generation algorithm which is based on the classification formula is outperformed by the general algorithm which is based on replacement conversion; it has great significance to solve the enumeration of the necklace combinational scheme, especially the structural problems of combinational scheme, by using group theory and computer.

A coupled two-dimensional main chain torsional potential for protein dynamics: generation and implementation.

Science.gov (United States)

Li, Yongxiu; Gao, Ya; Zhang, Xuqiang; Wang, Xingyu; Mou, Lirong; Duan, Lili; He, Xiao; Mei, Ye; Zhang, John Z H

2013-09-01

Main chain torsions of alanine dipeptide are parameterized into coupled 2-dimensional Fourier expansions based on quantum mechanical (QM) calculations at M06 2X/aug-cc-pvtz//HF/6-31G** level. Solvation effect is considered by employing polarizable continuum model. Utilization of the M06 2X functional leads to precise potential energy surface that is comparable to or even better than MP2 level, but with much less computational demand. Parameterization of the 2D expansions is against the full main chain torsion space instead of just a few low energy conformations. This procedure is similar to that for the development of AMBER03 force field, except unique weighting factor was assigned to all the grid points. To avoid inconsistency between quantum mechanical calculations and molecular modeling, the model peptide is further optimized at molecular mechanics level with main chain dihedral angles fixed before the calculation of the conformational energy on molecular mechanical level at each grid point, during which generalized Born model is employed. Difference in solvation models at quantum mechanics and molecular mechanics levels makes this parameterization procedure less straightforward. All force field parameters other than main chain torsions are taken from existing AMBER force field. With this new main chain torsion terms, we have studied the main chain dihedral distributions of ALA dipeptide and pentapeptide in aqueous solution. The results demonstrate that 2D main chain torsion is effective in delineating the energy variation associated with rotations along main chain dihedrals. This work is an implication for the necessity of more accurate description of main chain torsions in the future development of ab initio force field and it also raises a challenge to the development of quantum mechanical methods, especially the quantum mechanical solvation models.

Shape distortion and dimensional precision in tungsten heavy alloy liquid phase sintering

International Nuclear Information System (INIS)

Wuwen Yi; German, R.M.; Lu, P.K.

2001-01-01

Microstructure effects on densification and shape distortion in liquid phase sintering of tungsten heavy alloy were investigated. Microstructure parameters such as the solid volume fraction, dihedral angle, initial porosity, and pore size were varied to measure densification and distortion behavior during LPS using W-Ni-Cu alloys. Green compacts were formed using ethylene-bis-stearamide as a pore-forming agent with the amount of polymer controlling the initial porosity. Different initial pore sizes were generated by varying the polymer particle size. Dihedral angle was varied by changing the Ni:Cu ratio in the alloys. Finally, the solid volume fraction was adjusted via the tungsten content. Distortion was quantified using profiles determined with a coordinate measuring machine to calculate a distortion parameter. Sintering results showed that solid volume fraction and dihedral angle are the dominant factors on densification and distortion during liquid phase sintering. Distortion decreases with increasing solid volume fraction and dihedral angle, while initial porosity and pore size have no observable effect on distortion at nearly full densification. Various strategies emerge to improve distortion control in liquid phase sintering. (author)

1-[2-(4-Bromobenzyloxy-2-phenylethyl]-1H-1,2,4-triazole

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Tuncer Hökelek

2008-10-01

Full Text Available In the molecule of the title compound, C17H16BrN3O, the triazole ring is oriented at dihedral angles of 6.14 (9° and 82.08 (9°, respectively, with respect to the phenyl and bromobenzene rings. The dihedral angle between the bromobenzene and phenyl rings is 87.28 (7°. The intramolecular C—H...O hydrogen bond results in the formation of a planar five-membered ring, which is oriented at a dihedral angle of 0.13 (6° with respect to the bromobenzene ring. There is an intermolecular C—H...π contact between a methylene group and the bromobenzene ring.

N-{4-[4-(4-Fluorophenyl-1-(2-methoxyethyl-2-methylsulfanyl-1H-imidazol-5-yl]-2-pyridyl}-2-methyl-3-phenylpropionamide

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Stefan Laufer

2009-12-01

Full Text Available In the crystal structure of the title compound, C28H29FN4O2S, the imidazole ring makes dihedral angles of 11.85 (7, 73.33 (7 and 22.83 (8° with the 4-fluorophenyl, pyridine and phenyl rings, respectively. The 4-fluorophenyl ring makes dihedral angles of 77.91 (7 and 26.93 (8° with the pyridine and phenyl rings, respectively. The phenyl and pyridine rings are nearly perpendicular, making a dihedral angle of 86.47 (9°. The crystal packing shows an intermolecular N—H...O hydrogen-bonding interaction between the N—H and carbonyl groups of the amide functions.

5-(2,5-Dioxooxolan-3-yl-8-methyl-3,3a,4,5-tetrahydro-1H-naphtho[1,2-c]furan-1,3-dione

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Y. Z. Guo

2013-02-01

Full Text Available In the title compound, C17H14O6, the dihedral angle between the two anhydride rings is 76.01 (8°while the dihedral angles between the benzene and anhydride rings are 42.60 (7 and 68.94 (7°. The cyclohexene ring of the tetrahydronaphthalene unit exhibits an envelope conformation.

Equilibrium configurations of the conducting liquid surface in a nonuniform electric field

Science.gov (United States)

Zubarev, N. M.; Zubareva, O. V.

2011-01-01

Possible equilibrium configurations of the free surface of a conducting liquid deformed by a nonuniform external electric field are investigated. The liquid rests on an electrode that has the shape of a dihedral angle formed by two intersecting equipotential half-planes (conducting wedge). It is assumed that the problem has plane symmetry: the surface is invariant under shift along the edge of the dihedral angle. A one-parametric family of exact solutions for the shape of the surface is found in which the opening angle of the region above the wedge serves as a parameter. The solutions are valid when the pressure difference between the inside and outside of the liquid is zero. For an arbitrary pressure difference, approximate solutions to the problem are constructed and it is demonstrated the approximation error is small. It is found that, when the potential difference exceeds a certain threshold value, equilibrium solutions are absent. In this case, the region occupied by the liquid disintegrates, the disintegration scenario depending on the opening angle.

2-(4-Methylphenyl-5-[({[5-(4-methylphenyl-1,3,4-thiadiazol-2-yl]sulfanyl}methylsulfanyl]-1,3,4-thiadiazole

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Jing-wen Yu

2012-03-01

Full Text Available In the title compound, C19H16N4S4, the molecules exhibit a butterfly conformation, where the thiadiazole and attached benzene rings in two wings are almost coplanar, with dihedral angles of 0.8 (3 and 0.9 (3°, respectively, while the two thiadiazole rings form a dihedral angle of 46.3 (3°.

Fluid Distribution in Synthetic Wet Halite Rocks : Inference from Measured Elastic Wave Velocity and Electrical Conductivity

Science.gov (United States)

Watanabe, T.; Kitano, M.

2011-12-01

Intercrystalline fluid can significantly affect rheological and transport properties of rocks. Its influences are strongly dependent on its distribution. The dihedral angle between solid and liquid phases has been widely accepted as a key parameter that controls solid-liquid textures. The liquid phase is not expected to be interconnected if the dihedral angle is larger than 60 degree. However, observations contradictory to dihedral angle values have been reported. Watanabe (2010) suggested the coexistence of grain boundary fluid with a positive dihedral angle. For good understanding of fluid distribution, it is thus critical to study the nature of grain boundary fluid. We have developed a high pressure and temperature apparatus for study of intercrystalline fluid distribution. It was specially designed for measurements of elastic wave velocities and electrical conductivity. The apparatus mainly consists of a conventional cold-seal vessel with an external heater. The pressure medium is silicon oil of the viscosity of 0.1 Pa s. The pressure and temperature can be controlled from 0 to 200 MPa and from 20 to 200 C, respectively. Dimensions of a sample are 9 mm in diameter, and 15 mm in length. Halite-water system is used as an analog for crustal rocks. The dihedral angle has been studied systematically at various pressure and temperature conditions [Lewis and Holness, 1996]. The dihedral angle is larger than 60 degree at lower pressure and temperature. It decreases to be smaller than 60 degree with increasing pressure and temperature. A sample is prepared by cold-pressing and annealing of wet NaCl powder. Optical examination has shown that synthesized samples are microstructurally homogeneous. Grains are polygonal and equidimensional with a mean diameter of 100 micrometer. Grain boundaries vary from straight to bowed and 120 degree triple junctions are common. Gas and fluid bearing inclusions are visible on the grain boundaries. There are spherical inclusions or

t-3-Benzyl-r-2,c-6-diphenylpiperidin-4-one oxime

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R. Arulraj

2016-12-01

Full Text Available In the title compound, C24H24N2O [systematic name: (E-3-benzyl-2,6-diphenylpiperidin-4-one oxime], the piperidine ring adopts a slightly distorted chair conformation and the phenyl rings and the benzyl group substituents are attached equatorially. The oxime group makes a dihedral angle of 42.88 (12° with the piperidine ring. The dihedral angle between the phenyl rings is 71.96 (8°. The benzyl ring makes dihedral angles of 63.01 (8 and 59.35 (8° with the two phenyl rings. In the crystal, molecules are linked by O—H...N hydrogen bonds, forming C(7 chains along the c axis. The chains are linked by C—H...π interactions, forming slabs lying parallel to the bc plane.

Phenyl N-(2-methylphenylcarbamate

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Durre Shahwar

2009-07-01

Full Text Available In the title compound, C14H13NO2, the aromatic rings attached to the O and N atoms make dihedral angles of 62.65 (9 and 38.28 (11°, respectively, with the central carbamate group. The benzene rings are oriented at a dihedral angle of 39.22 (10°. In the crystal, a very weak C—H...π interaction occurs.

The Q-angle and sport

DEFF Research Database (Denmark)

Hahn, Thomas; Foldspang, Anders

1997-01-01

Quadriceps muscle contraction tends to straighten the Q angle. We expected that sports comprising a high amount of quadriceps training could be associated with low Q angles. The aim of the present study was to estimate the Q angle in athletes and to investigate its potential associations with par......Quadriceps muscle contraction tends to straighten the Q angle. We expected that sports comprising a high amount of quadriceps training could be associated with low Q angles. The aim of the present study was to estimate the Q angle in athletes and to investigate its potential associations...... with participation in sport. Three hundred and thirty-nine athletes had their Q angle measured. The mean of right-side Q angles was higher than left side, and the mean Q angle was higher in women than in men. The Q angle was positively associated with years of jogging, and negatively with years of soccer, swimming...... and sports participation at all. It is concluded that the use of Q angle measurements is questionable....

Methyl 2-(2,2-dimethyl-3a,6a-dihydrofuro[3,2-d][1,3]dioxol-5-yl-4-oxo-4H-chromene-3-carboxylate

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Devadasan Velmurugan

2013-08-01

Full Text Available In the title molecule, C18H16O7, the dioxolane ring adopts an envelope conformation with the dimethyl-substituted C atom as the flap. The furan ring is almost coplanar with the pyran ring, with a dihedral angle of 1.04 (10° between the planes, and it makes a dihedral angle of 67.97 (11° with the mean plane of the dioxolane ring. The latter makes a dihedral angle of 67.15 (10° with the pyran ring. The O atom attached to the pyran ring deviates by −0.009 (1 Å. The crystal packing features C—H...O hydrogen bonds, forming a three-dimensional structure. The methoxycarbonyl atoms are disordered over two positions, with a refined occupancy ratio of 0.508 (18:0.492 (18.

4-Chloro-N-o-tolylbenzamide

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Hiroyuki Ishida

2008-10-01

Full Text Available In the molecule of the title compound, C14H12ClNO, the two benzene rings are close to coplanar [dihedral angle = 7.85 (4°]. The amide N—C=O plane makes dihedral angles of 34.04 (4 and 39.90 (3°, respectively, with the 4-chloro- and 2-methylphenyl rings. In the crystal structure, intermolecular N—H...O hydrogen bonds link the molecules into chains.

12-Benzoyl-2-methylnaphtho[2,3-b]indolizine-6,11-dione

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Yun Liu

2011-06-01

Full Text Available In the title compound, C24H15NO3, the fused naphthaquinone–pyrrole unit is approximately planar, the naphthaquinone ring system making a dihedral angle of 2.91 (10° with the pyrrole ring. The plane of the pyrrole ring makes a dihedral angle 61.64 (14° with that of the benzene ring of the benzoylmethylene group. The crystal structure is stablized by intramolecular C—H...O interactions.

Crystal structure of N′-diphenylmethylidene-5-methyl-1H-pyrazole-3-carbohydrazide

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Khalid Karrouchi

2015-11-01

Full Text Available In the title compound, C18H16N4O, the planes of the phenyl rings are approximately perpendicular to each other [dihedral angle = 78.07 (8°] and form dihedral angles of 56.43 (8 and 24.59 (8° with the pyrazole ring. In the crystal, molecules are linked by N—H...O hydrogen bonds to form one-dimensional chains parallel to the [010] direction.

Solar electricity potentials and optimal angles for mounting solar ...

African Journals Online (AJOL)

The need for harnessing solar energy using solar panels mounted at optimal inclination angles in the six geopolitical zones of Nigeria is presented. The optimal angle for mounting solar panels as presented by Photovoltaic Geographic Information System (PVGIS) ranges from 11º to 14º in the Southern zone and 13º to 16º ...

Solutions of the Yang-Baxter equation: Descendants of the six-vertex model from the Drinfeld doubles of dihedral group algebras

International Nuclear Information System (INIS)

Finch, P.E.; Dancer, K.A.; Isaac, P.S.; Links, J.

2011-01-01

The representation theory of the Drinfeld doubles of dihedral groups is used to solve the Yang-Baxter equation. Use of the two-dimensional representations recovers the six-vertex model solution. Solutions in arbitrary dimensions, which are viewed as descendants of the six-vertex model case, are then obtained using tensor product graph methods which were originally formulated for quantum algebras. Connections with the Fateev-Zamolodchikov model are discussed.

(11-Methylpyrido[2,3-b][1,4]benzodiazepin-6-yl(phenylmethanone

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Fuqiang Shi

2010-09-01

Full Text Available In the title compound, C20H15N3O, the diazepine ring adopts a boat conformation. The dihedral angle between pyridine and benzene rings is 55.2 (1°. The benzoyl phenyl ring forms dihedral angles of 49.4 (1 and 75.9 (1°, respectively, with the pyridine and benzene rings. In the crystal, molecules are linked into centrosymmetric dimers by pairs of C—H...N hydrogen bonds.

(4-Nitrophenylmethyl 2,3-dihydro-1H-pyrrole-1-carboxylate: crystal structure and Hirshfeld analysis

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Julio Zukerman-Schpector

2018-03-01

Full Text Available In the title compound, C12H12N2O4, the dihydropyrrole ring is almost planar (r.m.s. deviation = 0.0049 Å and is nearly coplanar with the adjacent C2O2 residue [dihedral angle = 4.56 (9°], which links to the 4-nitrobenzene substituent [dihedral angle = 4.58 (8°]. The molecule is concave, with the outer rings lying to the same side of the central C2O2 residue and being inclined to each other [dihedral angle = 8.30 (7°]. In the crystal, supramolecular layers parallel to (10-5 are sustained by nitrobenzene-C—H...O(carbonyl and pyrrole-C—H...O(nitro interactions. The layers are connected into a three-dimensional architecture by π(pyrrole–π(nitrobenzene stacking [inter-centroid separation = 3.7414 (10 Å] and nitro-O...π(pyrrole interactions.

Analysis of binding energy activity of TIBO and HIV-RT based on ...

African Journals Online (AJOL)

Tetrahydro-imidazo[4,5,l-jk][1,4]-benzodiazepin-2 (1 H)one (TIBO) is a noncompetitive non nucleotide antiretroviral drug with a specific allosteric binding site of HIV-1 RT. The conformational analysis shows that the effect of the drug depends on the potential energy which varied due to the beta rotatable dihedral angles (N6 ...

The nonabelian tensor square of Bieberbach group of dimension five with dihedral point group of order eight

Science.gov (United States)

Fauzi, Wan Nor Farhana Wan Mohd; Idrus, Nor'ashiqin Mohd; Masri, Rohaidah; Sarmin, Nor Haniza

2014-07-01

The nonabelian tensor product was originated in homotopy theory as well as in algebraic K-theory. The nonabelian tensor square is a special case of the nonabelian tensor product where the product is defined if the two groups act on each other in a compatible way and their action are taken to be conjugation. In this paper, the computation of nonabelian tensor square of a Bieberbach group, which is a torsion free crystallographic group, of dimension five with dihedral point group of order eight is determined. Groups, Algorithms and Programming (GAP) software has been used to assist and verify the results.

Propagation-of-uncertainty from contact angle and streaming potential measurements to XDLVO model assessments of membrane-colloid interactions.

Science.gov (United States)

Muthu, Satish; Childress, Amy; Brant, Jonathan

2014-08-15

Membrane fouling assessed from a fundamental standpoint within the context of the Derjaguin-Landau-Verwey-Overbeek (DLVO) model. The DLVO model requires that the properties of the membrane and foulant(s) be quantified. Membrane surface charge (zeta potential) and free energy values are characterized using streaming potential and contact angle measurements, respectively. Comparing theoretical assessments for membrane-colloid interactions between research groups requires that the variability of the measured inputs be established. The impact that such variability in input values on the outcome from interfacial models must be quantified to determine an acceptable variance in inputs. An interlaboratory study was conducted to quantify the variability in streaming potential and contact angle measurements when using standard protocols. The propagation of uncertainty from these errors was evaluated in terms of their impact on the quantitative and qualitative conclusions on extended DLVO (XDLVO) calculated interaction terms. The error introduced into XDLVO calculated values was of the same magnitude as the calculated free energy values at contact and at any given separation distance. For two independent laboratories to draw similar quantitative conclusions regarding membrane-foulant interfacial interactions the standard error in contact angle values must be⩽2.5°, while that for the zeta potential values must be⩽7 mV. Copyright © 2014 Elsevier Inc. All rights reserved.

Rotational spectrum and conformational composition of cyanoacetaldehyde, a compound of potential prebiotic and astrochemical interest.

Science.gov (United States)

Møllendal, Harald; Margulès, Laurent; Motiyenko, Roman A; Larsen, Niels Wessel; Guillemin, Jean-Claude

2012-04-26

The rotational spectrum of cyanoacetaldehyde (NCCH(2)CHO) has been investigated in the 19.5-80.5 and 150-500 GHz spectral regions. It is found that cyanoacetaldehyde is strongly preferred over its tautomer cyanovinylalcohol (NCCH═CHOH) in the gas phase. The spectra of two rotameric forms of cyanoacetaldehyde produced by rotation about the central C-C bond have been assigned. The C-C-C-O dihedral angle has an unusual value of 151(3)° from the synperiplanar (0°) position in one of the conformers denoted I, while this dihedral angle is exactly synperiplanar in the second rotamer called II, which therefore has C(s) symmetry. Conformer I is found to be preferred over II by 2.9(8) kJ/mol from relative intensity measurements. A double minimum potential for rotation about the central C-C bond with a small barrier maximum at the exact antiperiplanar (180°) position leads to Coriolis perturbations in the rotational spectrum of conformer I. Selected transitions of I were fitted to a Hamiltonian allowing for this sort of interaction, and the separation between the two lowest vibrational states was determined to be 58794(14) MHz [1.96112(5) cm(-1)]. Attempts to include additional transitions in the fits using this Hamiltonian failed, and it is concluded that it lacks interaction terms to account satisfactorily for all the observed transitions. The situation was different for II. More than 2000 transitions were assigned and fitted to the usual Watson Hamiltonian, which allowed very accurate values to be determined not only for the rotational constants, but for many centrifugal distortion constants as well. Two vibrationally excited states were also assigned for this form. Theoretical calculations were performed at the B3LYP, MP2, and CCSD levels of theory using large basis sets to augment the experimental work. The predictions of these calculations turned out to be in good agreement with most experimental results.

Small angle x-ray scattering as a potential tool for cancer diagnosis

International Nuclear Information System (INIS)

Kitchen, M.; Siu, K.K.W.; Lewis, R.A.

2003-01-01

Full text: The diagnostic potential of Small Angle X-ray Scattering (SAXS) patterns has recently been investigated for malignant breast tissues. The demonstrated systematic differences in the scattering signatures of malignant, benign and normal breast tissue specimens are believed to arise from the changes in the fibrous proteins making up the extracellular matrix (ECM) with the disease progression. The technique may also have the potential to aid in the diagnosis of gliomas, a highly aggressive type of brain tumour. Although complex and difficult to interpret, SAXS data from malignant tissues may prove to be a more effective classification tool than conventional histology techniques. Here we present the methodology of the technique, as applied to breast cancer and brain tumour specimens to date, and some directions for future investigations. We also present a novel analysis method, which employs wavelet decomposition and a naive Bayesian classifier, as a potential semi-automated classification tool

1-(4-Methyl­phenyl­sulfon­yl)-5,6-di­nitro-1H-indazole

Science.gov (United States)

Oulemda, Bassou; Rakib, El Mostapha; Abbassi, Najat; Saadi, Mohamed; El Ammari, Lahcen

2014-01-01

In the title compound, C14H10N4O6S, the indazole ring system is almost perpendicular to the tosyl ring, as indicated by the dihedral angle of 89.40 (9)° between their planes. The dihedral angles between the indazole system and the nitro groups are 57.0 (3) and 31.9 (3)°. In the crystal, mol­ecules are linked by C—H⋯O inter­actions, forming chains running along [100]. PMID:24526962

1-(4-Methylphenylsulfonyl-5,6-dinitro-1H-indazole

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Bassou Oulemda

2014-01-01

Full Text Available In the title compound, C14H10N4O6S, the indazole ring system is almost perpendicular to the tosyl ring, as indicated by the dihedral angle of 89.40 (9° between their planes. The dihedral angles between the indazole system and the nitro groups are 57.0 (3 and 31.9 (3°. In the crystal, molecules are linked by C—H...O interactions, forming chains running along [100].

10-Ethyl-3-(5-methyl-1,3,4-oxadiazol-2-yl-10H-phenothiazine

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Li-Cheng Sun

2012-03-01

Full Text Available In the title compound, C17H15N3OS, the phenothiazine ring system is slightly bent, with a dihedral angle of 13.68 (7° between the benzene rings. The dihedral angle between the oxadiazole ring and the adjacent benzene ring is 7.72 (7°. In the crystal, a π–π interaction with a centroid–centroid distance of 3.752 (2 Å is observed between the benzene rings of neighbouring molecules.

3-Fluoro-N-(p-tolylbenzamide

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Aamer Saeed

2008-11-01

Full Text Available In the crystal structure of the title compound, C14H12FNO, the amide –NHCO– mean plane makes dihedral angles of 28.6 (2 and 37.5 (2° with the mean planes through the fluorobenzene and methylbenzene units, respectively. The dihedral angle between the two benzene ring mean planes is 65.69 (10°. In the crystal structure, molecules are linked through N—H...O hydrogen bonds and stack along the b axis.

3-(Pyridin-2-ylcoumarin

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Yu-Xia Da

2010-11-01

Full Text Available In the title compound, C14H9NO2, the dihedral angle between the pyridine ring and the lactone ring is 10.40 (3°. The coumarin ring system is nearly planar, with a dihedral angle of 1.40 (2° between the lactone and benzene rings. An intramolecular C—H...O hydrogen bond occurs. In the crystal, inversion dimers linked by pairs of C—H...O interactions occur, generating R22(14 loops.

4-{2-Methoxy-6-[(4-methylphenyliminomethyl]phenoxy}phthalonitrile

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Orhan Büyükgüngör

2009-05-01

Full Text Available In the molecule of the title compound, C23H17N3O2, the methoxyphenyl ring is oriented at dihedral angles of 13.34 (12 and 88.83 (12° with respect to the methylphenyl and phthalonitrile rings, respectively; the dihedral angle between methylphenyl and phthalonitrile rings is 89.67 (10°. In the crystal structure, weak intermolecular C—H...N interactions link molecules into chains. A weak C—H...π interaction is also found..

(R-[(R-3-Benzyl-2-oxooxazolidin-4-yl][4-(methylsulfonylphenyl]methyl acetate

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Feng Li

2014-05-01

Full Text Available The structure of the title compound, C20H21NO6S, is of interest with respect to its antibacterial properties. The oxazolidine ring makes dihedral angles of 79.63 (14 and 56.16 (12° with the phenyl and benzene rings, respectively, while the phenyl and benzene rings make a dihedral angle of 64.37 (13°. In the crystal, non-classical C—H...O hydrogen bonds link adjacent molecules along the c axis.

[3-(5-Nitro-2-furyl-1-phenyl-1H-pyrazol-4-yl](phenylmethanone

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Jia Hao Goh

2010-05-01

Full Text Available In the title pyrazole compound, C20H13N3O4, an intramolecular C—H...O hydrogen bond generates a seven-membered ring, producing an S(7 ring motif. The essentially planar furan and pyrazole rings [maximum deviations of 0.002 (1 and 0.007 (1 Å, respectively] are coplanar with each other, forming a dihedral angle of 3.06 (10°. The pyrazole ring forms dihedral angles of 8.51 (9 and 56.81 (9° with the two benzene rings. The nitro group is coplanar with the attached furan ring, as indicated by the dihedral angle of 2.5 (3°. In the crystal packing, intermolecular C—H...O hydrogen bonds link adjacent molecules into two-molecule-wide chains along the a axis. The crystal packing is further stabilized by weak intermolecular C—H...π and π–π interactions [centroid–centroid distance = 3.4441 (10 Å].

9-Butyl-9H-carbazole

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2009-03-01

Full Text Available The title compound, C16H17N, is a carbazole derivative that has been designed and synthesized as a potential organic electronic device, such as an OLED. The tricyclic aromatic ring system is essentially planar, the two outer rings making a dihedral angle of 4.8 (1°. No classical hydrogen bonds are observed in the crystal structure.

2-Benzylsulfanyl-N-(1,3-dimethylimidazolidin-2-ylideneaniline

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Ulrich Flörke

2013-04-01

Full Text Available The molecular structure of the title compound, C18H21N3S, shows a twisted conformation with a dihedral angle of 67.45 (4° between the aromatic ring planes and an N—C—C—S torsion angle of −5.01 (13°. The imidazolidine ring and the aniline moiety make a dihedral angle of 56.03 (4° and the asscociated C—N—C angle is 125.71 (10°. The guanidine-like C=N double bond is clearly localized, with a bond length of 1.2879 (14 Å. The C—S—C angle is 102.12 (5° and the S—C(aromatic and S—C bond lengths are 1.7643 (11 and 1.8159 (12 Å.

3,5-Bis(4-meth­oxy­phen­yl)-1-phenyl-4,5-dihydro-1H-pyrazole

OpenAIRE

Baktır, Zeliha; Akkurt, Mehmet; Samshuddin, S.; Narayana, B.; Yathirajan, H. S.

2011-01-01

In the title compound, C23H22N2O2, the central pyrazole ring is nearly planar (r.m.s. deviation = 0.046 Å) and it makes a dihedral angle of 18.5 (2)° with the phenyl ring. The dihedral angles between the phenyl and the two methoxy-substituted phenyl rings are 26.2 (2) and 80.6 (2)°. The crystal structure is stabilized by C—H...π stacking interactions and weak π–π interactions [cen...

1-[3-(4-Chlorophenyl-5-(4-methoxyphenyl-4,5-dihydro-1H-pyrazol-1-yl]ethanone

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Hoong-Kun Fun

2012-04-01

Full Text Available In the title compound, C18H17ClN2O2, the benzene rings form dihedral angles of 6.69 (6 and 74.88 (5° with the 4,5-dihydro-1H-pyrazole ring. The benzene rings form a dihedral angle of 76.67 (5° with each other. In the crystal, molecules are linked via bifurcated (C,C–H...O hydrogen bonds into chains along [010]. The crystal structure is further consolidated by C—H...π interactions.

2,4,8,10,13-Pentamethyl-6-phenyl-13,14-dihydro-12H-6λ5-dibenzo[d,i][1,3,7,2]dioxazaphosphecin-6-thione

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M. Krishnaiah

2010-01-01

Full Text Available In the title compound, C25H28NO2PS, the cyclodecene ring exhibits a crown conformation. The two dimethylbenzene rings which are fused symmetrically on either side of the ten-membered ring, make dihedral angles of 20.2 (1 and 18.0 (1°. The phenyl ring substituted at P is perpendicular to the heterocyclic ring, making a dihedral angle of 88.4 (1°. The crystal structure is stabilized by very weak intramolecular C—H...O hydrogen bonding.

Relating Trp-Glu dipeptide fluorescence to molecular conformation: the role of the discrete Chi 1 and Chi 2 angles.

Science.gov (United States)

Eisenberg, Azaria Solomon; Juszczak, Laura J

2013-07-05

Molecular dynamics (MD), coupled with fluorescence data for charged dipeptides of tryptophanyl glutamic acid (Trp-Glu), reveal a detailed picture of how specific conformation affects fluorescence. Fluorescence emission spectra and time-resolved emission measurements have been collected for all four charged species. MD simulations 20 to 30 ns in length have also been carried out for the Trp-Glu species, as simulation provides aqueous phase conformational data that can be correlated with the fluorescence data. The calculations show that each dipeptide species is characterized by a similar set of six, discrete Chi 1, Chi 2 dihedral angle pairs. The preferred Chi 1 angles--60°, 180°, and 300°--play the significant role in positioning the terminal amine relative to the indole ring. A Chi 1 angle of 60° results in the arching of the backbone over the indole ring and no interaction of the ring with the terminal amine. Chi 1 values of 180° and 300° result in an extension of the backbone away from the indole ring and a NH3 cation-π interaction with indole. This interaction is believed responsible for charge transfer quenching. Two fluorescence lifetimes and their corresponding amplitudes correlate with the Chi 1 angle probability distribution for all four charged Trp-Glu dipeptides. Fluorescence emission band maxima are also consistent with the proposed pattern of terminal amine cation quenching of fluorescence. Copyright © 2013 Wiley Periodicals, Inc.

3,5-Bis(4-meth-oxy-phen-yl)-1-phenyl-4,5-dihydro-1H-pyrazole.

Science.gov (United States)

Baktır, Zeliha; Akkurt, Mehmet; Samshuddin, S; Narayana, B; Yathirajan, H S

2011-01-12

In the title compound, C(23)H(22)N(2)O(2), the central pyrazole ring is nearly planar (r.m.s. deviation = 0.046 Å) and it makes a dihedral angle of 18.5 (2)° with the phenyl ring. The dihedral angles between the phenyl and the two meth-oxy-substituted phenyl rings are 26.2 (2) and 80.6 (2)°. The crystal structure is stabilized by C-H⋯π stacking inter-actions and weak π-π inter-actions [centriod-centroid distance = 3.891 (2) Å].

5-(2,4-Dichlorophenoxy-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde

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S. Madan Kumar

2016-07-01

Full Text Available In the crystal structure of the title compound, C17H12Cl2N2O2, the pyrazole ring makes dihedral angles of 65.0 (2 and 43.9 (2° with the dichlorophenyl and phenyl rings, respectively. The dihedral angle between the chlorophenyl and phenyl rings is 59.1 (2°. In the crystal, the molecules are linked by C—H...O hydrogen bonds and weak C—Cl...π and C—H...π interactions, generating a three-dimensional network.

(1E,2E-1,2-Bis(2,2-diphenylhydrazin-1-ylideneethane

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Angel Mendoza

2010-09-01

Full Text Available In the crystal structure of the title compound, C26H22N4, the molecule is located on an inversion centre and shows an E configuration with respect to each C=N bond. The dihedral angle between the phenyl rings in the diphenylhydrazone group is 83.69 (11°. These two rings make dihedral angles of 30.53 (15 and 84.53 (16° with the central N—N=C—C=N—N dihydrazonoethane plane. Intermolecular C—H...π interactions are observed.

(E-4-(2,5-Dimethoxybenzylidene-2-phenyl-1,3-oxazol-5(4H-one

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Abdullah Mohamed Asiri

2009-08-01

Full Text Available The central azalactone ring in the title compound, C18H15NO4, is planar (r.m.s. deviation 0.05, 0.12 Å in both independent molecules comprising the asymmetric unit. The benzylidene substituent is coplanar with this ring [dihedral angle between the planes = 1.8 (1° in the first molecule and 2.8 (1° in the second], as is the phenyl substitutent [dihedral angle between rings = 4.6 (1 and 9.7 (1°, respectively].

4,4′-Bipyridine–3-(thiophen-3-ylacrylic acid (1/2

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Malaichamy Sathiyendiran

2011-10-01

Full Text Available In the title 1/2 adduct, C10H8N2·2C7H6O2S, the dihedral angle between the pyridine rings is 18.41 (11°. In the thiopheneacrylic acid molecules, the dihedral angles between the respective thiophene and acrylic acid units are 5.52 (17° and 23.92 (9°. In the crystal, the components are linked via O—H...N hydrogen-bonding interactions, forming units of two 3-thiopheneacrylic acid molecules and one 4,4′-bipyridine molecule.

(Z-3-Benzyl-2-[(2-phenylcyclohex-2-enylimino]-1,3-thiazolidin-4-one

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Chin Wei Ooi

2012-08-01

Full Text Available The title compound, C22H22N2OS, exists in a Z configuration with respect to the N=C bond. The cyclohexene ring adopts a distorted sofa conformation. The thiazolidine ring is essentially planar, with a maximum deviation of 0.030 (2 Å, and forms dihedral angles of 76.66 (6 and 74.55 (6° with the terminal phenyl rings. The dihedral angle between the phenyl rings is 71.55 (7°. In the crystal, a C—H...π interaction is observed.

(1-Phenyl-1H-1,2,3-triazol-4-ylmethyl pyridine-3-carboxylate

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Zakirjon Karimov

2010-07-01

Full Text Available In the title compound, C15H12N4O2, the dihedral angle between the planes of the nicotinoyloxy fragment and triazole ring is 88.61 (5°. The dihedral angle between the planes of triazole and benzene rings is 16.54 (11°. The crystal structure is stabilized by intermolecular C—H...N, C—H...O and C—H...π(triazole hydrogen bonds and aromatic π–π stacking interactions between the benzene and triazole rings [centroid–centroid distance = 3.895 (1 Å

Characteristic conformation of Mosher's amide elucidated using the cambridge structural database.

Science.gov (United States)

Ichikawa, Akio; Ono, Hiroshi; Mikata, Yuji

2015-07-16

Conformations of the crystalline 3,3,3-trifluoro-2-methoxy-2-phenylpropanamide derivatives (MTPA amides) deposited in the Cambridge Structural Database (CSD) were examined statistically as Racid-enantiomers. The majority of dihedral angles (48/58, ca. 83%) of the amide carbonyl groups and the trifluoromethyl groups ranged from -30° to 0° with an average angle θ1 of -13°. The other conformational properties were also clarified: (1) one of the fluorine atoms was antiperiplanar (ap) to the amide carbonyl group, forming a staggered conformation; (2) the MTPA amides prepared from primary amines showed a Z form in amide moieties; (3) in the case of the MTPA amide prepared from a primary amine possessing secondary alkyl groups (i.e., Mosher-type MTPA amide), the dihedral angles between the methine groups and the carbonyl groups were syn and indicative of a moderate conformational flexibility; (4) the phenyl plane was inclined from the O-Cchiral bond of the methoxy moiety with an average dihedral angle θ2 of +21°; (5) the methyl group of the methoxy moiety was ap to the ipso-carbon atom of the phenyl group.

Discrete Haar transform and protein structure.

Science.gov (United States)

Morosetti, S

1997-12-01

The discrete Haar transform of the sequence of the backbone dihedral angles (phi and psi) was performed over a set of X-ray protein structures of high resolution from the Brookhaven Protein Data Bank. Afterwards, the new dihedral angles were calculated by the inverse transform, using a growing number of Haar functions, from the lower to the higher degree. New structures were obtained using these dihedral angles, with standard values for bond lengths and angles, and with omega = 0 degree. The reconstructed structures were compared with the experimental ones, and analyzed by visual inspection and statistical analysis. When half of the Haar coefficients were used, all the reconstructed structures were not yet collapsed to a tertiary folding, but they showed yet realized most of the secondary motifs. These results indicate a substantial separation of structural information in the space of Haar transform, with the secondary structural information mainly present in the Haar coefficients of lower degrees, and the tertiary one present in the higher degree coefficients. Because of this separation, the representation of the folded structures in the space of Haar transform seems a promising candidate to encompass the problem of premature convergence in genetic algorithms.

1H NMR of High-Potential Iron-Sulfur Protein from the Purple Non-Sulfur Bacterium Rhodoferax fermentans

DEFF Research Database (Denmark)

Ciurli, Stefano; Cremonini, Mauro Andrea; Kofod, Pauli

1996-01-01

residues bound to the [4Fe-4S]3+/2+ cluster have been performed using one-dimensional NOE and exchange spectroscopy experiments. 1H-NMR hyperfine shifts and relaxation rates of cluster-bound Cys β-CH2 protons indicate that in the [4Fe-4S]3+ cluster one iron ion can be formally described as Fe(III), while......Oxidized and reduced forms of high-potential iron-sulfur protein (HiPIP) from the purple non-sulfur photosynthetic bacterium Rhodoferux fermentans have been characterized using 1H-NMR spectroscopy. Pairwise and sequence-specific assignments of hyperfine-shifted 1H-NMR signals to protons of cysteine...... longitudinal relaxation rates of Cys β-CH2 protons in HiPIPs from six different sources as a function of the Fe-S-Cβ-Cα dihedral angle, indicate that the major contribution is due to a dipolar metal-centered mechanism, with a non-negligeable contribution from a ligand-centered dipolar mechanism which involves...

Crystal and molecular structure of (2Z,5Z-3-(2-methoxyphenyl-2-[(2-methoxyphenylimino]-5-(4-nitrobenzylidenethiazolidin-4-one

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Ahmed Djafri

2017-04-01

Full Text Available In the title compound, C24H19N3O5S, the thiazole ring (r.m.s. deviation = 0.012 Å displays a planar geometry and is surrounded by three fragments, two methoxyphenyl and one nitrophenyl. The thiazole ring is almost in the same plane as the nitrophenyl ring, making a dihedral angle of 20.92 (6°. The two methoxyphenyl groups are perpendicular to the thiazole ring [dihedral angles of 79.29 (6 and 71.31 (7° and make a dihedral angle of 68.59 (7°. The molecule exists in an Z,Z conformation with respect to the C=N imine bond. In the crystal, a series of C—H...N, C—H...O and C—H...S hydrogen bonds, augmented by several π–π(ring interactions, produce a three-dimensional architecture of molecules stacked along the b-axis direction. The experimentally derived structure is compered with that calculated theoretically using DFT(B3YLP methods.

Structural investigation of HIV-1 nonnucleoside reverse transcriptase inhibitors: 2-Aryl-substituted benzimidazoles

Science.gov (United States)

Ziółkowska, Natasza E.; Michejda, Christopher J.; Bujacz, Grzegorz D.

2009-11-01

Acquired immunodeficiency syndrome (AIDS) caused by the human immunodeficiency virus (HIV) is one of the most destructive epidemics in history. Inhibitors of HIV enzymes are the main targets to develop drugs against that disease. Nonnucleoside reverse transcriptase inhibitors of HIV-1 (NNRTIs) are potentially effective and nontoxic. Structural studies provide information necessary to design more active compounds. The crystal structures of four NNRTI derivatives of 2-aryl-substituted N-benzyl-benzimidazole are presented here. Analysis of the geometrical parameters shows that the structures of the investigated inhibitors are rigid. The important geometrical parameter is the dihedral angle between the planes of the π-electron systems of the benzymidazole and benzyl moieties. The values of these dihedral angles are in a narrow range for all investigated inhibitors. There is no significant difference between the structure of the free inhibitor and the inhibitor in the complex with RT HIV-1. X-ray structures of the investigated inhibitors are a good basis for modeling enzyme-inhibitor interactions in rational drug design.

3,5-Bis(4-methoxyphenyl-1-phenyl-4,5-dihydro-1H-pyrazole

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Zeliha Baktır

2011-02-01

Full Text Available In the title compound, C23H22N2O2, the central pyrazole ring is nearly planar (r.m.s. deviation = 0.046 Å and it makes a dihedral angle of 18.5 (2° with the phenyl ring. The dihedral angles between the phenyl and the two methoxy-substituted phenyl rings are 26.2 (2 and 80.6 (2°. The crystal structure is stabilized by C—H...π stacking interactions and weak π–π interactions [centriod–centroid distance = 3.891 (2 Å].

3,5-Bis(4-meth­oxy­phen­yl)-1-phenyl-4,5-dihydro-1H-pyrazole

Science.gov (United States)

Baktır, Zeliha; Akkurt, Mehmet; Samshuddin, S.; Narayana, B.; Yathirajan, H. S.

2011-01-01

In the title compound, C23H22N2O2, the central pyrazole ring is nearly planar (r.m.s. deviation = 0.046 Å) and it makes a dihedral angle of 18.5 (2)° with the phenyl ring. The dihedral angles between the phenyl and the two meth­oxy-substituted phenyl rings are 26.2 (2) and 80.6 (2)°. The crystal structure is stabilized by C—H⋯π stacking inter­actions and weak π–π inter­actions [centriod–centroid distance = 3.891 (2) Å]. PMID:21523013

Ethyl 2-(1,2,3,4-tetrahydrospiro[carbazole-3,2′-[1,3]dioxolan]-9-ylacetate

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Philipp M. G. Löffler

2009-04-01

Full Text Available In the title compound, C18H21NO4, the hydrogenated six-membered ring of the carbazole unit adopts a half-chair conformation. The dioxolane ring and ethylacetate substituent point to opposite sides of the carbazole plane. The ethylacetate substituent adopts an essentially fully extended conformation, and its mean plane forms a dihedral angle of 83.8 (1° with respect to the carbazole mean plane. The molecules are arranged into stacks in which the carbazole planes form a dihedral angle of 4.4 (1° and have an approximate interplanar separation of 3.6 Å.

3,5-Bis[1-acetyl-5-(4-chlorophenyl-4,5-dihydro-1H-pyrazol-3-yl]-2,6-dimethylpyridine tetrahydrofuran solvate

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Qun Qian

2008-07-01

Full Text Available In the title compound, C29H27Cl2N5O2·C4H8O, the polycyclic system is composed of three parts: one central pyridine ring substituted by two functionalized pyrazoline rings. The dihedral angles between the central pyridine plane and pyrazoline planes are 5.11 (1 and 13.99 (1°, whereas the dihedral angles between each chlorophenyl plane and the attached pyrazoline planes are 88.65 (1 and 83.87 (1°. Molecules are linked by intermolecular C—H...O hydrogen bonds, forming a three-dimensional network.

5,6-Dipropylphthalazino[2,3-a]cinnoline-8,13-dione

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G. Vimala

2016-04-01

Full Text Available In the title compound, C22H22N2O2, the two central fused pyridazine rings have screw-boat conformations and the dihedral angle between their mean planes is 36.22 (8°. The mean plane of the cinnoline ring system makes a dihedral angle of 46.56 (5° with the mean plane of the phthalazine ring to which it is fused. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming chains along the b axis. The chains are reinforced by C—H...π interactions.

2-Methyl-3-(2-methylphenyl-4-oxo-3,4-dihydroquinazolin-8-yl 4-bromobenzene-1-sulfonate

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Edward R. T. Tiekink

2012-03-01

Full Text Available The title molecule, C22H17BrN2O4S, has a twisted U shape, the dihedral angle between the quinazolin-4-one and bromobenzene ring systems being 46.25 (8°. In order to avoid steric clashes with adjacent substituents on the quinazolin-4-one ring, the N-bound tolyl group occupies an orthogonal position [dihedral angle = 89.59 (8°]. In the crystal, molecules are connected into a three-dimensional architecture by C—H...O interactions, with the ketone O atom accepting two such bonds and a sulfonate O atom one.

The crystal structure of 2-[5-(dimethylaminonaphthalene-1-sulfonamido]phenyl 5-(dimethylaminonaphthalene-1-sulfonate

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Kittipong Chainok

2015-10-01

Full Text Available The complete molecule of the title compound, C30H29N3O5S2, is generated by a crystallographic twofold axis: the O atom and NH group attached to the central benzene ring are statistically disordered. The dihedral angle between the naphthalene ring system and the central benzene ring is 52.99 (6°, while the pendant naphthalene ring systems subtend a dihedral angle of 68.17 (4°. An intramolecular C—H...O hydrogen bond closes an S(6 ring. In the crystal, the molecules are linked by weak C—H...O hydrogen bonds.

3-(4-Chlorobenzoyl-4-(4-chlorophenyl-1-phenethylpiperidin-4-ol

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Abdullah Aydın

2011-06-01

Full Text Available In the title compound, C26H25Cl2NO2, the piperidine ring adopts a chair conformation with a cis configuration of the carbonyl and hydroxy substituents. The dihedral angle between the aromatic rings of the chlorobenzene groups is 24.3 (2°. The phenyl ring forms dihedral angles of 59.4 (3 and 44.1 (3° with the benzene rings. In the crystal, molecules are linked by intermolecular O—H...N and C—H...O hydrogen bonds and C—H...π interactions into layers parallel to the bc plane.

5-[(1-Benzyl-1H-1,2,3-triazol-4-ylmethyl]-5H-dibenzo[b,f]azepine

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N. K. Lokanath

2013-12-01

Full Text Available In the title compound, C24H20N4, the azepine ring adopts a boat conformation. The dihedral angle between the benzene rings fused to the azepine ring is 49.40 (9°. The triazole ring makes a dihedral angle of 77.88 (9° with the terminal phenyl ring. In the crystal, molecules are linked via C—H...π interactions and a parallel slipped π–π interaction [centroid–centroid distance = 3.7324 (9, normal distance = 3.4060 (6 and slippage = 1.526 Å], forming a three-dimensional network.

6,7-Dichloro-3-(2,4-dichlorobenzylquinoxalin-2(1H-one

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Jinpeng Zhang

2012-08-01

Full Text Available In the title compound, C15H8Cl4N2O, the quinoxaline ring system is almost planar, with a dihedral angle between the benzene and pyrazine rings of 3.1 (2°. The 2,4-dichlorophenyl ring is approximately perpendicular to the pyrazine ring, with a dihedral angle of 86.47 (13° between them. The crystal packing features intermolecular N—H...O hydrogen bonds and π–π stacking interactions, with centroid–centroid distances in the range 3.699 (3–4.054 (3 Å.

4-{(E-[2-(4-Iodobutoxybenzylidene]amino}-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H-one

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Hoong-Kun Fun

2010-07-01

Full Text Available The title Schiff base compound, C22H24IN3O2, adopts an E configuration about the central C=N bond. The pyrazolone ring makes a dihedral angle of 49.68 (10° with its attached phenyl ring. The phenolate plane makes dihedral angles of 16.78 (9 and 50.54 (9°, respectively, with the pyrazolone ring and the terminal phenyl ring. An intramolecular C—H...O hydrogen bond generates an S(6 ring motif. In the crystal structure, an intermolecular C—H...O hydrogen bond is also observed.

3-Ethyl-5-(4-methoxyphenoxy-2-(pyridin-4-yl-3H-imidazo[4,5-b]pyridine

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S. Ranjith

2011-07-01

Full Text Available In the title compound, C20H18N4O2, the imidazopyridine fused ring system is almost perpendicular to the benzene ring [dihedral angle = 87.6 (5°]. The pyridine ring makes a dihedral angle of 35.5 (5° with the mean plane of the imidazopyridine fragment. The crystal structure is stabilized by an aromatic π–π stacking interaction between the phenyl rings of neighbouring molecules [centroid–centroid distance = 3.772 (2 Å, interplanar distance = 3.546 (2 Å and slippage = 1.286 (2 Å].

3-Benzyl-6-bromo-2-(2-furyl-3H-imidazo[4,5-b]pyridine

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Younès Ouzidan

2010-07-01

Full Text Available In the title molecule, C17H12BrN3O, the imidazopyridine ring system is almost coplanar with the furan ring [dihedral angle = 2.0 (3°]. The benzyl phenyl ring is oriented at dihedral angles of 85.2 (2 and 85.5 (1°, respectively, with respect to the furan ring and the imidazopyridine ring system. In the crystal, molecules are linked into chains propagating along the b axis by C—H...N hydrogen bonds. Adjacent chains are linked via short Br...Br contacts [3.493 (1 Å].

2-(Diphenylmethylidene-2,3-dihydro-1H-inden-1-one

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Helen Sheridan

2013-08-01

Full Text Available In the title molecule, C22H16O, the indanone ring system is approximately planar with a dihedral angle between the fused rings of 5.13 (14°. Two benzene rings are linked together at one side of a double bond, sitting on either side of the indanone ring system and making dihedral angles of 70.30 (12 and 44.74 (13° with it. In the crystal, hydrogen bonding is not present, but weak C—H...π or π–π interactions occur and molecules form a sheet-like structure in the bc plane.

Dynamic. cap alpha. -transfer polarisation potentials and the large angle scattering of /sup 16/O + /sup 28/Si

Energy Technology Data Exchange (ETDEWEB)

Hussein, M S; Aleixo, A N; Canto, L F; Carrilho, P; Donangelo, R; Paula, L.S. de

1987-07-01

A closed expression is derived for the dynamic ..cap alpha..-transfer polarisation potential for heavy-ion elastic scattering. The back-angle angular distributions for the elastic scattering of /sup 16/O + /sup 28/Si obtained by adding this polarisation potential to the E-18 interaction are shown to be in good agreement with the data if an ..cap alpha..-transfer spectroscopic factor of 0.4 is used.

Which potentials have to be surface peaked to reproduce large angle proton scattering at high energy?

International Nuclear Information System (INIS)

Raynal, J.

1990-01-01

Corrections to the usual form factors of the optical potential are studied with a view to getting a better fit for proton elastic scattering at large angles on 40 Ca at 497 and 800 MeV. When a real surface form factor is added to the central potential in the Schrodinger formalism, the experimental data are as well reproduced as in the standard Dirac formalism. Coupling to the strong 3 - collective state gives a better fit. The use of surface corrections to the imaginary Dirac potential also gives improved results. A slightly better fit is obtained by coupling to the 3 - state with, at the same time, a weakening of these corrections. Further corrections to the potential do not give significant improvements

(2E-3-(6-Chloro-2-methoxyquinolin-3-yl-1-(2-methyl-4-phenylquinolin-3-ylprop-2-en-1-one acetone monosolvate

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Edward R. T. Tiekink

2013-08-01

Full Text Available In the title solvate, C29H21ClN2O2·C3H6O, a prop-2-en-1-one bridge links two quinolinyl residues; the latter are almost perpendicular [dihedral angle = 78.27 (6°]. The dihedral angle between the quinonyl ring system and its pendant phenyl group is 59.78 (8°. A small twist in the bridging prop-2-en-1-one group is noted [O=C—C=C torsion angle = −10.6 (3°]. In the crystal, a three-dimensional architecture arises as a result of C—H...O and π–π stacking [centroid–centroid distances = 3.5504 (12–3.6623 (12 Å].

2-{[2-Methyl-3-(2-methylphenyl-4-oxo-3,4-dihydroquinazolin-8-yl]oxy}acetonitrile

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Adel S. El-Azab

2012-07-01

Full Text Available In the title compound, C18H15N3O2, the fused ring system is almost planar [the dihedral angle between the six-membered rings is 1.81 (6°]. The 2-tolyl ring is approximately orthogonal to this plane [dihedral angle = 83.03 (7°] as is the acetonitrile group [C—O—C—C torsion angle = 79.24 (14°] which is also syn to the methyl substituent of the tolyl group. In the crystal, supramolecular layers are formed in the bc plane mediated by C—H...O, C—H...N and C—H...π interactions. The tolyl group is disordered over two positions in a 0.852 (3:0.148 (3 ratio.

Structural Analysis of Molten NaNO3 by Molecular Dynamics Simulation

Science.gov (United States)

Tahara, Shuta; Toyama, Hiroshi; Shimakura, Hironori; Fukami, Takanori

2017-08-01

MD simulation for molten NaNO3 has been performed by using the Born-Mayer-Huggins-type potentials. The new structural features of molten NaNO3 are investigated by several analytical methods. The coordination-number and bond-angle distributions are similar to those of simple molten salts such as NaCl except for the variation caused by the different size of the anion and cation. Na+ ions are attracted toward O- ions, and get separated from N+ ions by Coulomb interactions. The distribution of the dihedral angle between NO3 - plannar ionic molecules has also been investigated.

Measurement of the Static Stability and Control and the Damping Derivatives of a 0.13-Scale Model of the Convair XFY-1 Airplane, TED No. NACA DE 368

Science.gov (United States)

Johnson, Joseph L.

1954-01-01

An investigation has been conducted to determine the static stability and control and damping in roll and yaw of a 0.13-scale model of the Convair XFY-1 airplane with propellers off from 0 deg to 90 deg angle of attack. The tests showed that a slightly unstable pitch-up tendency occurred simultaneously with a break in the normal-force curve in the angle-of-attack range from about 27 deg to 36 deg. The top vertical tail contributed positive values of static directional stability and effective dihedral up to an angle of attack of about 35 deg. The bottom tail contributed positive values of static directional stability but negative values of effective dihedral throughout the angle-of-attack range. Effectiveness of the control surfaces decreased to very low values at the high angles of attack, The model had positive damping in yaw and damping in roll about the body axes over the angle-of-attack range but the damping in yaw decreased to about zero at 90 deg angle of attack.

DNA minor groove electrostatic potential: influence of sequence-specific transitions of the torsion angle gamma and deoxyribose conformations.

Science.gov (United States)

Zhitnikova, M Y; Shestopalova, A V

2017-11-01

The structural adjustments of the sugar-phosphate DNA backbone (switching of the γ angle (O5'-C5'-C4'-C3') from canonical to alternative conformations and/or C2'-endo → C3'-endo transition of deoxyribose) lead to the sequence-specific changes in accessible surface area of both polar and non-polar atoms of the grooves and the polar/hydrophobic profile of the latter ones. The distribution of the minor groove electrostatic potential is likely to be changing as a result of such conformational rearrangements in sugar-phosphate DNA backbone. Our analysis of the crystal structures of the short free DNA fragments and calculation of their electrostatic potentials allowed us to determine: (1) the number of classical and alternative γ angle conformations in the free B-DNA; (2) changes in the minor groove electrostatic potential, depending on the conformation of the sugar-phosphate DNA backbone; (3) the effect of the DNA sequence on the minor groove electrostatic potential. We have demonstrated that the structural adjustments of the DNA double helix (the conformations of the sugar-phosphate backbone and the minor groove dimensions) induce changes in the distribution of the minor groove electrostatic potential and are sequence-specific. Therefore, these features of the minor groove sizes and distribution of minor groove electrostatic potential can be used as a signal for recognition of the target DNA sequence by protein in the implementation of the indirect readout mechanism.

[meso-5,10,15,20-Tetrakis(5-bromothiophen-2-ylporphyrinato-κ4N,N′,N′′,N′′′]nickel(II

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R. Prasath

2012-04-01

Full Text Available The NiII atom in the title porphyrin complex, [Ni(C36H16Br4N4S4], is in a square-planar geometry defined by four pyrrole N atoms. There is considerable buckling in the porphyrin ring with the dihedral angles between the N4 donor set and the pyrrole rings being in the range 17.0 (3–18.8 (3°. Each of the six-membered chelate rings is twisted about an Ni—N bond and the dihedral angles between diagonally opposite chelate rings are 13.08 (15 and 13.45 (11°; each pair of rings is orientated in opposite directions. The bromothienyl rings are twisted out of the plane of the central N4 core with dihedral angles in the range 51.7 (2–74.65 (19°. Supramolecular chains along [001] are formed through C—H...Br interactions in the crystal packing. Three of the four bromothienyl units are disordered over two coplanar positions of opposite orientation with the major components being in 0.691 (3, 0.738 (3 and 0.929 (9 fractions.

Full cyclic coordinate descent: solving the protein loop closure problem in Cα space

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Hamelryck Thomas

2005-06-01

Full Text Available Abstract Background Various forms of the so-called loop closure problem are crucial to protein structure prediction methods. Given an N- and a C-terminal end, the problem consists of finding a suitable segment of a certain length that bridges the ends seamlessly. In homology modelling, the problem arises in predicting loop regions. In de novo protein structure prediction, the problem is encountered when implementing local moves for Markov Chain Monte Carlo simulations. Most loop closure algorithms keep the bond angles fixed or semi-fixed, and only vary the dihedral angles. This is appropriate for a full-atom protein backbone, since the bond angles can be considered as fixed, while the (φ, ψ dihedral angles are variable. However, many de novo structure prediction methods use protein models that only consist of Cα atoms, or otherwise do not make use of all backbone atoms. These methods require a method that alters both bond and dihedral angles, since the pseudo bond angle between three consecutive Cα atoms also varies considerably. Results Here we present a method that solves the loop closure problem for Cα only protein models. We developed a variant of Cyclic Coordinate Descent (CCD, an inverse kinematics method from the field of robotics, which was recently applied to the loop closure problem. Since the method alters both bond and dihedral angles, which is equivalent to applying a full rotation matrix, we call our method Full CCD (FCDD. FCCD replaces CCD's vector-based optimization of a rotation around an axis with a singular value decomposition-based optimization of a general rotation matrix. The method is easy to implement and numerically stable. Conclusion We tested the method's performance on sets of random protein Cα segments between 5 and 30 amino acids long, and a number of loops of length 4, 8 and 12. FCCD is fast, has a high success rate and readily generates conformations close to those of real loops. The presence of constraints

Ethyl 2-(1,2,3,4-tetrahydro­spiro­[carba­zole-3,2′-[1,3]dioxolan]-9-yl)acetate

Science.gov (United States)

Löffler, Philipp M. G.; Ulven, Trond; Bond, Andrew D.

2009-01-01

In the title compound, C18H21NO4, the hydrogenated six-membered ring of the carbazole unit adopts a half-chair conformation. The dioxolane ring and ethyl­acetate substituent point to opposite sides of the carbazole plane. The ethyl­acetate substituent adopts an essentially fully extended conformation, and its mean plane forms a dihedral angle of 83.8 (1)° with respect to the carbazole mean plane. The mol­ecules are arranged into stacks in which the carbazole planes form a dihedral angle of 4.4 (1)° and have an approximate inter­planar separation of 3.6 Å. PMID:21582427

6-Chloro-3-[5-(3-methoxy-8-methyl-4-quinolyl-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]-2-methyl-4-phenylquinoline

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Hoong-Kun Fun

2009-11-01

Full Text Available In the title compound, C36H29ClN4O, the dihydropyrazole ring adopts an envelope conformation. The two quinoline ring systems (r.m.s. deviations = 0.029 and 0.018 Å are oriented at a dihedral angle of 71.43 (4°. One of the quinoline rings makes a dihedral angle of 65.40 (7° with the phenyl substituent. In the crystal, molecules are linked into chains along the b axis by intermolecular C—H...N hydrogen bonds. In addition, C—H...π and π–π [centroid–centroid distance = 3.7325 (8 Å] interactions are observed.

4-(1,3-Diphenyl-4,5-dihydro-1H-pyrazol-5-yl-1,3-diphenyl-1H-pyrazole

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Hoong-Kun Fun

2011-11-01

Full Text Available The title compound, C30H24N4, contains two pyrazole rings and four phenyl rings. The pyrazole rings are essentially planar, with maximum deviations of 0.003 (1 and 0.066 (1 Å and make a dihedral angle of 73.43 (6°. The two pyrazole rings make dihedral angles of 40.08 (6, 9.28 (6, 15.78 (8 and 17.25 (7° with their attached phenyl rings. In the crystal, there are no significant intermolecular hydrogen-bonding interactions. The crystal structure is stabilized by C—H...π interactions.

3-Ethyl-5-(4-meth­oxy­phen­oxy)-2-(pyridin-4-yl)-3H-imidazo[4,5-b]pyridine

Science.gov (United States)

Ranjith, S.; SubbiahPandi, A.; Suresh, A. D.; Pitchumani, K.

2011-01-01

In the title compound, C20H18N4O2, the imidazopyridine fused ring system is almost perpendicular to the benzene ring [dihedral angle = 87.6 (5)°]. The pyridine ring makes a dihedral angle of 35.5 (5)° with the mean plane of the imidazopyridine fragment. The crystal structure is stabilized by an aromatic π–π stacking inter­action between the phenyl rings of neighbouring mol­ecules [centroid–centroid distance = 3.772 (2) Å, inter­planar distance = 3.546 (2) Å and slippage = 1.286 (2) Å]. PMID:21837144

3′,6′-Bis(diethylamino-3H-spiro[2-benzothiophene-1,9′-xanthene]-3-thione

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Bing-Yuan Su

2008-11-01

Full Text Available The title compound, C28H30N2OS2, was obtained by thionation of 3′,6′-bis(diethylamino-3H-spiro[isobenzofuran-1,9′-xanthene]-3-one with 2,4-bis(p-methoxyphenyl-1,3-dithiadiphosphetane disulfide (Lawesson's reagent. The planes of the two benzene rings of the xanthene system are inclined at a dihedral angle of 17.4 (1°, and the plane of the dithiophthalide group and the planes through the two benzene rings of the xanthene system make dihedral angles of 80.2 (1 and 82.8 (1°, respectively.

2-Carboxy-6-(quinolin-1-ium-8-yloxybenzoate

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Jin Xie

2012-05-01

Full Text Available In the zwitterionic title compound, C17H11NO5, the dihedral angle between the two aromatic rings is 76.90 (7°. The dihedral angles between the carboxyl groups and the benzene ring are 64.02 (9 and 21.67 (9°, the larger angle being associated with an intramolecular N—H...Ocarboxyl hydrogen bond, resulting from proton transfer from the carboxylic acid group to the quinoline N atom and giving an S(9 ring motif. In the crystal, molecules are connected by O—H...O hydrogen bonds into chains extending along the b-axis direction. An overall two-dimensional network structure is formed through π–π interactions between the quinoline rings [minimum ring-centroid separation = 3.6068 (6 Å].

Magnetic exchange in {Gd(III)-radical} complexes: method assessment, mechanism of coupling and magneto-structural correlations.

Science.gov (United States)

Gupta, Tulika; Rajeshkumar, Thayalan; Rajaraman, Gopalan

2014-07-28

Density functional studies have been performed on ten different {Gd(III)-radical} complexes exhibiting both ferro and antiferromagnetic exchange interaction with an aim to assess a suitable exchange-correlation functional within DFT formalism. This study has also been extended to probe the mechanism of magnetic coupling and to develop suitable magneto-structural correlations for this pair. Our method assessments reveal the following order of increasing accuracy for the evaluation of J values compared to experimental coupling constants: B(40HF)LYP X3LYP < B3LYP < B2PLYP. Grimme's double-hybrid functional is found to be superior compared to other functionals tested and this is followed very closely by the conventional hybrid B3LYP functional. At the basis set front, our calculations reveal that the incorporation of relativistic effect is important in these calculations and the relativistically corrected effective core potential (ECP) basis set is found to yield better Js compared to other methods. The supposedly empty 5d/6s/6p orbitals of Gd(III) are found to play an important role in the mechanism of magnetic coupling and different contributions to the exchange terms are probed using Molecular Orbital (MO) and Natural Bond Orbital (NBO) analysis. Magneto-structural correlations for Gd-O distances, Gd-O-N angles and Gd-O-N-C dihedral angles are developed where the bond angles as well as dihedral angle parameters are found to dictate the sign and strength of the magnetic coupling in this series.

Součet úhlů ve čtyřstěnu

Czech Academy of Sciences Publication Activity Database

Brandts, J.; Cihangir, A.; Křížek, Michal

2015-01-01

Roč. 60, č. 2 (2015), s. 113-122 ISSN 0032-2423 R&D Projects: GA ČR GA14-02067S Institutional support: RVO:67985840 Keywords : dihedral angle * solid angle * nonobtuse tetrahedron * optimal bounds Subject RIV: BA - General Mathematics http://hdl.handle.net/10338.dmlcz/144405

Gauche effect in 1,2-difluoroethane. Hyperconjugation, bent bonds, steric repulsion.

Science.gov (United States)

Goodman, Lionel; Gu, Hongbing; Pophristic, Vojislava

2005-02-17

Natural bond orbital deletion calculations show that whereas the gauche preference arises from vicinal hyperconjugative interaction between anti C-H bonds and C-F* antibonds, the cis C-H/C-F* interactions are substantial (approximately 25% of the anti interaction). The established significantly >60 degrees FCCF dihedral angle for the equilibrium conformer can then be rationalized in terms of the hyperconjugation model alone by taking into account both anti interactions that maximize near 60 degrees and the smaller cis interactions that maximize at a much larger dihedral angle. This explanation does not invoke repulsive forces to rationalize the 72 degrees equilibrium conformer angle. The relative minimum energy for the trans conformer is the consequence of a balance between decreasing hyperconjugative stabilization and decreasing steric destabilization as the FCCF torsional angle approaches 180 degrees . The torsional coordinate is predicted to be strongly contaminated by CCF bending, with the result that approximately half of the trans --> gauche stabilization energy stems from mode coupling.

Benzyl N-((S-2-hydroxy-1-{N′-[(E-2-methoxybenzylidene]hydrazinecarbonyl}ethylcarbamate from synchrotron data

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Alessandra C. Pinheiro

2010-04-01

Full Text Available A U-shaped conformation is found in the title compound, C19H21N3O5, with the benzene rings lying to the same side of the molecule; the dihedral angle between them is 10.83 (16°. The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13°. The carbonyl groups lie approximately at right angles to each other [O—C...C—O pseudo torsion angle of 107.7 (3°], and the conformation about the C12=N3 bond [1.279 (4 Å] is E. An intramolecular Ncb—H...Ohy (cb = carbmate and hy = hydroxy hydrogen bond occurs, generating an S(6 loop. In the crystal, intermolecular Oh—H...Oca (ca = carbonyl and Nhz—H...Oca (hz = hydrazine hydrogen bonds lead to the formation of a supramolecular chain, two molecules thick, which propagates along the a axis; these are connected by C—H...Oca contacts.

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

Science.gov (United States)

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M; Yusoff, Siti Fairus M

2014-09-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro-benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro-benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl-thio-amide group and its attached ring is 12.98 (10)°. The major twists in the mol-ecule occur about the C-N-N-C bonds [torsion angle = -138.7 (2)°] and the Car-Car-C-N (ar = aromatic) bonds [-132.0 (2)°]. An intra-molecular N-H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯S hydrogen bonds, generating (001) sheets. Weak C-H⋯O and C-H⋯F inter-actions are also observed.

(Z-3-(Anthracen-9-yl-1-(2-ethoxyphenylprop-2-en-1-oneThis paper is dedicated to the late His Royal Highness Prince Mahidol of Songkla for his contributions to the development of medical education in Thailand on the occasion of Mahidol Day which falls on the 24th September.

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Hoong-Kun Fun

2010-10-01

Full Text Available The molecule of the title chalcone, C25H20O2, consisting of 2-ethoxyphenyl and anthracene rings bridged by a prop-2-en-1-one unit, is twisted and exists in the Z configuration with respect to the central C=C bond. The dihedral angle between the benzene and anthracene rings is 78.17 (9°. The propene unit makes dihedral angles of 44.5 (2 and 81.1 (2° with the benzene and anthracene rings, respectively. The ethoxy substituent is almost coplanar with the attached benzene ring [C—O—C—C torsion angle = 178.57 (19°]. In the crystal, molecules are linked into chains along the a axis by weak C—H...O interactions. The crystal structure is further stabilized by C—H...π interactions.

4-[(E-({4-[(4-Aminophenylsulfonyl]phenyl}iminomethyl]phenol ethanol monosolvate

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Sadaf Afzal

2012-06-01

Full Text Available In the title compound, C19H16N2O3S·C2H6O, the 4-hydroxybenzylidene group is oriented at dihedral angles of 73.17 (7 and 77.06 (7° with respect to the aniline groups. The sulfonyl group make dihedral angles of 44.89 (13 and 59.16 (12° with the adjacent aniline groups. In the crystal, a two-dimensional polymeric network parallel to (010 is formed by N—H...O, O—H...N and O—H...O hydrogen bonds. There also exist π–π interactions with a distance of 3.5976 (18 Å between the centroids of hydroxyphenyl rings.

Bis(1-benzyl-1H-benzimidazole-κN3dichloridozinc

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Rachid Bouhfid

2014-03-01

Full Text Available In the title compound, [ZnCl2(C14H12N22], the ZnII atom exhibits a distorted tetrahedral coordination geometry involving two chloride anions and two N-atom donors from 1-benzyl-1H-benzimidazole ligands. In both ligands, the benzyl and benzimidazole rings are nearly perpendicular [dihedral angles = 81.7 (2 and 81.5 (2°]. The two benzimidazole systems are essentially planar [maximum deviations = 0.015 (3 and 0.020 (2 Å] and form a dihedral angle of 78.09 (8°. In the crystal, centrosymmetrically related molecules are linked by pairs of C—H...Cl hydrogen bonds into chains parallel to the a axis.

2-Chloro-N-(3-chlorophenylbenzamide

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B. Thimme Gowda

2008-07-01

Full Text Available In the structure of the the title compound, C13H9Cl2NO, the N—H and C=O groups are mutually trans. Furthermore, the conformation of the C=O group is syn to the ortho-chloro group in the benzoyl ring, while the N—H bond is anti to the meta-chloro group in the aniline ring. The amide group forms dihedral angles of 89.11 (19 and 22.58 (37°, respectively, with the benzoyl and aniline rings, while the benzoyl and aniline rings form a dihedral angle of 69.74 (14°. The molecules are linked into infinite chains through intermolecular N—H...O hydrogen bonds.

1-O-Acetyl-3,4,6-tri-O-benzyl-2-C-bromomethyl-2-deoxy-α-d-glucopyranose

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Henok H. Kinfe

2013-01-01

Full Text Available In the title compound, C30H33BrO6, the pyranose ring adopts a chair conformation. Two of the O-benzyl phenyl rings lie almost perpendicular to C/C/C/O plane formed by the ring atoms not attached to these O-benzyl phenyl rings, and form dihedral angles of 85.1 (2 and 64.6 (2°, while the third O-benzyl phenyl ring is twisted so that it makes a dihedral angle 34.9 (2° to this C/C/C/O plane. This twist is ascribed to the formation of an S(8 loop stabilized by a weak intramolecular C—H...O hydrogen bond.

6-Hydroxy-5-[(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-enyl(4-nitrophenylmethyl]-1,3-dimethylpyrimidine-2,4(1H,3H-dione

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N. Sureshbabu

2013-11-01

Full Text Available In the title compound, C21H23N3O7, the pyrimidinedione ring adopts a screw-boat conformation, whereas the cyclohexenone ring adopts an envelope conformation, with the C atom bearing the methyl groups as the flap atom. The dihedral angle between the mean planes of the pyrimidinedione and cyclohexenone rings is 58.78 (2°. The pyrimidinedione and cyclohexenone rings form dihedral angles of 59.94 (3 and 54.73 (2°, respectively, with the 4-nitrophenyl ring. Relatively strong intramolecular O—H...O hydrogen bonds are observed. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming a chain along the c-axis direction.

(Z-3-(4-Chlorophenyl-1-(2,4-difluorophenyl-2-(1H-1,2,4-triazol-1-ylprop-2-en-1-one

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Xin-Mei Peng

2012-06-01

Full Text Available The asymmetric unit of the title compound, C17H10ClF2N3O, contains three independent molecules. In each molecule, the C=C bond has a cis conformation with respect to the triazole and chlorophenyl groups. The dihedral angles formed by the triazole ring with the diflurophenyl and chlorophenyl benzene rings, respectively, are 20.10 (14 and 73.22 (15, 25.31 (15 and 84.44 (15, and 16.44 (13 and 61.72 (14° in the three molecules while the dihedral angles between the benzene rings are 66.54 (13, 85.82 (12 and 58.37 (12°.

Random close packing in protein cores.

Science.gov (United States)

Gaines, Jennifer C; Smith, W Wendell; Regan, Lynne; O'Hern, Corey S

2016-03-01

Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions ϕ ≈ 0.75, a value that is similar to close packing of equal-sized spheres. A limitation of these analyses was the use of extended atom models, rather than the more physically accurate explicit hydrogen model. The validity of the explicit hydrogen model was proved in our previous studies by its ability to predict the side chain dihedral angle distributions observed in proteins. In contrast, the extended atom model is not able to recapitulate the side chain dihedral angle distributions, and gives rise to large atomic clashes at side chain dihedral angle combinations that are highly probable in protein crystal structures. Here, we employ the explicit hydrogen model to calculate the packing fraction of the cores of over 200 high-resolution protein structures. We find that these protein cores have ϕ ≈ 0.56, which is similar to results obtained from simulations of random packings of individual amino acids. This result provides a deeper understanding of the physical basis of protein structure that will enable predictions of the effects of amino acid mutations to protein cores and interfaces of known structure.

A comparative molecular dynamics study of diffusion of n-decane ...

Indian Academy of Sciences (India)

Administrator

Abstract. Molecular dynamics simulations are reported on the structure and dynamics of n-decane and. 3-methylpentane in zeolite NaY. We have calculated several properties such as the center of mass-center of mass rdf, the end-end distance distribution, bond angle distribution and dihedral angle distribution. We.

Predictors of Intraocular Pressure After Phacoemulsification in Primary Open-Angle Glaucoma Eyes with Wide Versus Narrower Angles (An American Ophthalmological Society Thesis).

Science.gov (United States)

Lin, Shan C; Masis, Marisse; Porco, Travis C; Pasquale, Louis R

2017-08-01

To assess if narrower-angle status and anterior segment optical coherence tomography (AS-OCT) parameters can predict intraocular pressure (IOP) drop in primary open-angle glaucoma (POAG) patients after cataract surgery. This was a prospective case series of consecutive cataract surgery patients with POAG and no peripheral anterior synechiae (PAS) using a standardized postoperative management protocol. Preoperatively, patients underwent gonioscopy and AS-OCT. The same glaucoma medication regimen was resumed by 1 month. Potential predictors of IOP reduction included narrower-angle status by gonioscopy and angle-opening distance (AOD500) as well as other AS-OCT parameters. Mixed-effects regression adjusted for use of both eyes and other potential confounders. We enrolled 66 eyes of 40 glaucoma patients. The IOP reduction at 1 year was 4.2±3 mm Hg (26%, P gonioscopy. By AOD500 classification, the narrower-angle group had 3.4±3 mm Hg (21%, P <.001) reduction vs 2.5±3 mm Hg (16%, P <.001) in the wide-angle group ( P =.031 for difference). When the entire cohort was assessed, iris thickness, iris area, and lens vault were correlated with increasing IOP reduction at 1 year ( P <.05 for all). In POAG eyes, cataract surgery lowered IOP to a greater degree in the narrower-angle group than in the wide-angle group, and parameters relating to iris thickness and area, as well as lens vault, were correlated with IOP reduction. These findings can guide ophthalmologists in their selection of cataract surgery as a potential management option.

A code to compute the action-angle transformation for a particle in an abritrary potential well

International Nuclear Information System (INIS)

Berg, J.S.; Warnock, R.L.

1995-01-01

For a Vlasov treatment of longitudinal stability under an arbitrary wake field, with the solution of the Haiessinski equation as the unperturbed distribution, it is important to have the action-angle transformation for the distorted potential well in a convenient form. The authors have written a code that gives the transformation q,p → J, φ, with q(J,φ) as a Fourier series in φ, the Fourier coefficients and the Hamiltonian H(J) being spline functions of J in C 2 (having continuous second derivatives)

Pramana – Journal of Physics | Indian Academy of Sciences

Indian Academy of Sciences (India)

The theoretical parameters of the transparent conducting metal oxides were calculated using DFT/B3LYP/LANL2DZ method. The optimised bond parameters such as bond lengths, bond angles and dihedral angles were calculated using the same theory. The non-linear optical property of the title compound was calculated ...

2-Methyl-N-(4-methylbenzoylbenzenesulfonamide

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B. Thimme Gowda

2010-04-01

Full Text Available The asymmetric unit of the title compound, C15H15NO3S, contains two independent molecules. The conformations of the N—C bonds in the C—SO2—NH—C(O segments have gauche torsions with respect to the SO bonds. Further, the molecules are twisted at the S atoms with torsion angles of −53.1 (2 and 61.2 (2° in the two molecules. The dihedral angles between the sulfonyl benzene rings and the —SO2—NH—C—O segments are 86.0 (1 and 87.9 (1°. Furthermore, the dihedral angles between the sulfonyl and the benzoyl benzene rings are 88.1 (1 and 83.5 (1° in the two molecules. In the crystal, molecules are linked by N—H...O(S hydrogen bonds.

1-[2,2-Bis(1,3-benzimidazol-1-ylmethyl-3-bromopropyl]-1,3-benzimidazole

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Tai-Bao Wei

2011-07-01

Full Text Available The title compound, C26H23BrN6, has been synthesized as a potential ligand for the construction of metal–organic frameworks. The three benzimidazolyl groups present three potential coordination nodes. The dihedral angles between the benzimidazole ring systems are 74.03 (10, 66.49 (9 and 74.09 (9°. The structure contains large voids, which contain highly disordered solvent molecules that may be CH3CH2OH. Since the solvent molecules could not be located, the PLATON/SQUEEZE procedure [Spek (2009. Acta Cryst. D65, 148–155] was used.

1-[3-(2-Benzyloxy-6-hydroxy-4-methylphenyl-5-[3,5-bis(trifluoromethylphenyl]-4,5-dihydro-1H-pyrazol-1-yl]propane-1-one

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U. H. Patel

2013-06-01

Full Text Available In the title compound, C28H24F6N2O3, the mean plane of the central pyrazoline ring forms dihedral angles of 2.08 (9 and 69.02 (16° with the 2-benzyloxy-6-hydroxy-4-methylphenyl and 3,5-bis(trifluoromethylphenyl rings, respectively. The dihedral angle between the mean planes of the pyrazoline and 3,5-bis(trifluoromethylphenyl rings is 68.97 (9°. An intramolecular O—H...N hydrogen bond is observed, which forms an S(6 graph-set motif. In the crystal, pairs of weak C—H...F halogen interactions link the molecules into inversion dimers while molecular chains along [100] are formed by C—H...O contacts.

2-(4-Bromophenyl-5-fluoro-3-phenylsulfinyl-1-benzofuran

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Hong Dae Choi

2010-08-01

Full Text Available In the title compound, C20H12BrFO2S, the O atom and the phenyl group of the phenylsulfinyl substituent lie on opposite sides of the plane through the benzofuran fragment; the phenyl ring is nearly perpendicular to this plane [dihedral angle = 86.98 (6°]. The 4-bromophenyl ring is rotated slightly out of the benzofuran plane, making a dihedral angle of 1.56 (8°. The crystal structure features aromatic π–π interactions between the furan and phenyl rings of neighbouring molecules [centroid–centroid distance = 3.506 (3 Å], and an intermolecular C—H...π interaction. The crystal structure also exhibits a short intermolecular S...S contact [3.2635 (8 Å].

{4,4′,6,6′-Tetraiodo-2,2′-[(2,2-dimethylpropane-1,3-diylbis(nitrilomethanylylidene]diphenolato}nickel(II

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Hadi Kargar

2012-07-01

Full Text Available The asymmetric unit of the title compound, [Ni(C19H16I4N2O2], comprises half of a Schiff base complex. The NiII atom is located on a twofold rotation axis which also bisects the central C atom of the 2,2-dimethylpropane group of the ligand. The geometry around the NiII atom is distorted square-planar, with a dihedral angle of 21.7 (3° between the symmetry-related N/Ni/O coordination planes. The dihedral angle between the symmetry-related benzene rings is 27.9 (3°. In the crystal, short intermolecular I...I [3.8178 (9 and 3.9013 (10 Å] interactions are present.

N-{(2S-3-Hydroxy-4-[(5-methyl-1,3,4-thiadiazol-2-ylsulfanyl]-1-phenyl-2-butyl}-4-methylbenzenesulfonamide

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Claudia R. B. Gomes

2011-09-01

Full Text Available The thiadiazoyl and sulfonyl-benzene rings in the title compound, C20H23N3O3S3, are aligned to the same side of the molecule, forming a twisted `U' shape [dihedral angle = 77.6 (5°]. The benzyl-benzene ring is orientated in the opposite direction from the molecule but projects approximately along the same axis as the other rings [dihedral angle between benzene rings = 28.2 (5°] so that, overall, the molecule has a flattened shape. The hydroxy and amine groups are almost syn which enables the formation of intermolecular hydroxy-OH...N(thiadiazoyl and amine-H...O(sulfonyl hydrogen bonds leading to a supramolecular chain aligned along the a axis.

Ethyl 5-cyano-4-[2-(2,4-dichlorophenoxyacetamido]-1-phenyl-1H-pyrrole-3-carboxylate

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Jing Xu

2009-08-01

Full Text Available In the title compound, C22H17Cl2N3O4, the pyrrole ring and the 2,4-dichlorophenyl group form a dihedral angle of 8.14 (13°; the phenyl ring is twisted with respect to the pyrrole ring, forming a dihedral angle of 60.77 (14°. The C=O bond length is 1.213 (3 Å, indicating that the molecule is in the keto form, associated with a –CONH– group, and the amide group adopts the usual trans conformation. The molecule is stabilized by an intramolecular N—H...O hydrogen-bonding interaction. In the crystal, the stacked molecules exhibit intermolecular C—H...O and C—H...N hydrogen-bonding interactions.

2-(2,4-Dichlorophenyl-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylacetamide

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B. Narayana

2013-01-01

Full Text Available In the crystal structure of the title compound, C19H17Cl2N3O2, the molecules form dimers of the R22(10 type through N—H...O hydrogen bonding. As a result of steric repulsion, the amide group is rotated with respect to both the dichlorophenyl and 2,3-dihydro-1H-pyrazol-4-yl rings, making dihedral angles of 80.70 (13 and 64.82 (12°, respectively. The dihedral angle between the dichlorophenyl and 2,3-dihydro-1H-pyrazol-4-yl rings is 48.45 (5° while that between the 2,3-dihydro-1H-pyrazol-4-yl and phenyl rings is 56.33 (6°.

(3′R-3′-Benzyl-2′,3′-dihydro-1H-spiro[indole-3,1′-naphtho[2,3-c]pyrrole]-2,4′,9′-trione

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Garima Sharma

2012-09-01

Full Text Available In the title compound, C26H18N2O3, the maximum deviations from planarity for the tetrahydro-1H-naphtho[2,3-c]pyrrole and indoline rings systems are 0.091 (1 and 0.012 (2 Å, respectively. These ring systems make a dihedral angle of 89.95 (6° with each other and they make dihedral angles of 73.42 (8 and 71.28 (9°, respectively, with the benzene ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generate R22(8 loops and C—H...O interactions connect the dimers into corrugated sheets lying parallel to the bc plane.

(E-1-(2-Bromophenyl-3-(2,5-dimethoxyphenylprop-2-en-1-one

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Jerry P. Jasinski

2010-08-01

Full Text Available The title compound, C17H15BrO3, is a chalcone with the 2-bromophenyl and 2,5-dimethoxyphenyl rings bonded at opposite ends of a propene group. The dihedral angle between the mean planes of the ortho-bromo and ortho,meta-dimethoxy-substituted benzene rings is 77.3 (1°. The dihedral angles between the mean plane of the prop-2-ene-1-one group and the mean planes of the 2-bromophenyl and 2,5-dimethoxyphenyl rings are 58.6 (1 and 30.7 (4°, respectively. Weak C—H...O, C—H...Br and π–π stacking intermolecular interactions [centroid–centroid distance = 3.650 (2 Å] are present in the structure.

Dimethyl 4,4′-dihydroxy-3,3′-{[(3aRS,7aRS-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl]bis(methylene}dibenzoate

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Augusto Rivera

2011-11-01

Full Text Available The title compound, C25H30N2O6, has the imidazolidine ring in an envelope conformation. There are two intramolecular O—H...N hydrogen-bond interactions with graph-set motif S(6. The cyclohexane ring adopts a slightly distorted chair conformation. One methyl carboxylate substituent forms a dihedral angle of 12.00 (5° with the plane of the benzene ring, while the other methyl carboxylate group is almost coplanar, making a dihedral angle of 2.26 (9°. In the crystal, pairs of intermolecular C—H...O hydrogen bonds form racemic dimers, corresponding to an R22(18 graph-set motif. Further weak C—H...O interactions generate a chain running along the c axis.

A restraint molecular dynamics and simulated annealing approach for protein homology modeling utilizing mean angles

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Maurer Till

2005-04-01

Full Text Available Abstract Background We have developed the program PERMOL for semi-automated homology modeling of proteins. It is based on restrained molecular dynamics using a simulated annealing protocol in torsion angle space. As main restraints defining the optimal local geometry of the structure weighted mean dihedral angles and their standard deviations are used which are calculated with an algorithm described earlier by Döker et al. (1999, BBRC, 257, 348–350. The overall long-range contacts are established via a small number of distance restraints between atoms involved in hydrogen bonds and backbone atoms of conserved residues. Employing the restraints generated by PERMOL three-dimensional structures are obtained using standard molecular dynamics programs such as DYANA or CNS. Results To test this modeling approach it has been used for predicting the structure of the histidine-containing phosphocarrier protein HPr from E. coli and the structure of the human peroxisome proliferator activated receptor γ (Ppar γ. The divergence between the modeled HPr and the previously determined X-ray structure was comparable to the divergence between the X-ray structure and the published NMR structure. The modeled structure of Ppar γ was also very close to the previously solved X-ray structure with an RMSD of 0.262 nm for the backbone atoms. Conclusion In summary, we present a new method for homology modeling capable of producing high-quality structure models. An advantage of the method is that it can be used in combination with incomplete NMR data to obtain reasonable structure models in accordance with the experimental data.

Relaxation of structural parameters and potential coefficients of nonrigid molecules. General symmetry properties and application to ab initio study of 1,2-difluoroethane

Science.gov (United States)

Ha, T.-K.; Günthard, H. H.

1989-07-01

Structural parameters like bond length, bond angles, etc. and harmonic and anharmonic potential coefficients of molecules with internal rotation, inversion or puckering modes are generally assumed to vary with the large amplitude internal coordinates in a concerted manner (relaxation). Taking the coordinate vectors of the nuclear configuration of semirigid molecules with relaxation (SRMRs) as functions of relaxing structural parameters and finite amplitude internal coordinate, the isometric group of SRMRs is discussed and the irreducible representations of the latter are shown to classify into engendered and nonengendered ones. On this basis a concept of equivalent sets of nuclei SRMRs is introduced and an analytical expression is derived which defines the most general functional form of relaxation increments of all common types of structural parameters compatible with isometric symmetry. This formula is shown to be a close analog of an analytical expression defining the transformations induced by the isometric group of infinitesimal internal coordinates associated with typical structural parameters. Furthermore analogous formulae are given for the most general form of the relaxation of harmonic potential coefficients as a function of finite internal coordinates. The general relations are illustrated by ab initio calculations for 1,2-difluoroethane at the MP4/DZP//HF/4-31G* level for twelve values of the dihedral angle including complete structure optimization. The potential to internal rotation is found to be in essential agreement with experimentally derived data. For a complete set of ab initio structural parameters the associated relaxation increments are represented as Fourier series, which are shown to confirm the form predicted by the general formula and the isometric group of 1,2-difluoroethane. Depending on type of the structural parameters (bond length, bond angles, etc.), the associated relaxation increments appear to follow some simple rules. Similarly

65 Nigerian Journal of Chemical Research Vol.12, 2007 ...

African Journals Online (AJOL)

HP USER

Comparison of Experimental and Theoretical study of Solvent effect on Interfacial head group ... Department of Biochemistry, Mashhad Islamic Azad university of Medical science, Mashhad. ..... atoms were involved in critical dihedral angles,.

Crystal structure of 4-fluoro-N-[2-(4-fluoro­benzo­yl)hydra­zine-1-carbono­thio­yl]benzamide

Science.gov (United States)

Firdausiah, Syadza; Salleh Huddin, Ameera Aqeela; Hasbullah, Siti Aishah; Yamin, Bohari M.; Yusoff, Siti Fairus M.

2014-01-01

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro­benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro­benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl­thio­amide group and its attached ring is 12.98 (10)°. The major twists in the mol­ecule occur about the C—N—N—C bonds [torsion angle = −138.7 (2)°] and the Car—Car—C—N (ar = aromatic) bonds [−132.0 (2)°]. An intra­molecular N—H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol­ecules are linked by N—H⋯O and N—H⋯S hydrogen bonds, generating (001) sheets. Weak C—H⋯O and C—H⋯F inter­actions are also observed. PMID:25309250

2-Methoxy-4,6-diphenylnicotinonitrile

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Joel T. Mague

2014-02-01

Full Text Available In the title compound, C19H14N2O, the phenyl rings form dihedral angles of 10.90 (10 and 42.14 (6° with pyridine ring and an angle of 35.7 (2° with each other. The orientation of the methoxy group is defined by the C—O—C—N torsion angle of 4.9 (2°.

Sequence-specific unusual (1-->2)-type helical turns in alpha/beta-hybrid peptides.

Science.gov (United States)

Prabhakaran, Panchami; Kale, Sangram S; Puranik, Vedavati G; Rajamohanan, P R; Chetina, Olga; Howard, Judith A K; Hofmann, Hans-Jörg; Sanjayan, Gangadhar J

2008-12-31

This article describes novel conformationally ordered alpha/beta-hybrid peptides consisting of repeating l-proline-anthranilic acid building blocks. These oligomers adopt a compact, right-handed helical architecture determined by the intrinsic conformational preferences of the individual amino acid residues. The striking feature of these oligomers is their ability to display an unusual periodic pseudo beta-turn network of nine-membered hydrogen-bonded rings formed in the forward direction of the sequence by 1-->2 amino acid interactions both in solid-state and in solution. Conformational investigations of several of these oligomers by single-crystal X-ray diffraction, solution-state NMR, and ab initio MO theory suggest that the characteristic steric and dihedral angle restraints exerted by proline are essential for stabilizing the unusual pseudo beta-turn network found in these oligomers. Replacing proline by the conformationally flexible analogue alanine (Ala) or by the conformationally more constrained alpha-amino isobutyric acid (Aib) had an adverse effect on the stabilization of this structural architecture. These findings increase the potential to design novel secondary structure elements profiting from the steric and dihedral angle constraints of the amino acid constituents and help to augment the conformational space available for synthetic oligomer design with diverse backbone structures.

3-Methylpyridinium 4-nitrobenzoate–4-nitrobenzoic acid (1/1

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P. Sivakumar

2016-06-01

Full Text Available In the title compound, C6H8N+·C7H4NO4−·C7H5NO4, the cation is protonated at its pyridine N atom and makes a dihedral angle of 74.14 (12° with the benzene ring of the anion. The benzene ring of the neutral molecule and the pyridine ring are inclined at an angle of 79.20 (12°. The two benzene rings form a dihedral angle of 6.00 (12° with each other. In the crystal, N—H...O, O—H...O and C—H...O hydrogen bonds link the cations, anions and neutral molecules to form layers parallel to the ac plane, which enlose R44(18 ring motifs. The layers are linked by further C—H...O hydrogen bonds and C—H...π interactions, forming a three-dimensional supramolecular architecture.

Crystal structure of 2,2′-({[2-(tritylsulfanylbenzyl]azanediyl}bis(ethane-2,1-diylbis(isoindoline-1,3-dione

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Ulrich Flörke

2014-09-01

Full Text Available In the structure of the title compound, C46H37N3O4S, the planes of the two isoindoline units make a dihedral angle of 77.86 (3°. The dihedral angles between the benzyl plane and the isoindoline units are 79.56 (4 and 3.74 (9°. The geometry at the S atom shows a short [1.7748 (17 Å] S—Cbenzyl and a long [1.8820 (15 Å] S—Ctrityl bond and the C—S—C angle is 108.40 (7°. N—C bond lengths around the azane N atom are in the range 1.454 (2–1.463 (2 Å. he crystal packing exhibts two rather `non-classical' C—H...O hydrogen bonds that result in stacking of the molecules along the a as well as the b axis and give rise to columnar sub-structures.

Investigation of Aerodynamic Capabilities of Flying Fish in Gliding Flight

Science.gov (United States)

Park, H.; Choi, H.

In the present study, we experimentally investigate the aerodynamic capabilities of flying fish. We consider four different flying fish models, which are darkedged-wing flying fishes stuffed in actual gliding posture. Some morphological parameters of flying fish such as lateral dihedral angle of pectoral fins, incidence angles of pectoral and pelvic fins are considered to examine their effect on the aerodynamic performance. We directly measure the aerodynamic properties (lift, drag, and pitching moment) for different morphological parameters of flying fish models. For the present flying fish models, the maximum lift coefficient and lift-to-drag ratio are similar to those of medium-sized birds such as the vulture, nighthawk and petrel. The pectoral fins are found to enhance the lift-to-drag ratio and the longitudinal static stability of gliding flight. On the other hand, the lift coefficient and lift-to-drag ratio decrease with increasing lateral dihedral angle of pectoral fins.

10-(Prop-2-ynyl-10H-phenothiazine

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Younas Aouine

2010-11-01

Full Text Available In the molecule of the title compound, C15H11NS, the butterfly angle between the two planes defined by the two wings of the phenothiazine unit is 33.5 (8°. The dihedral angles between the two benzene rings and the propynyl group are 85 (4 and 63 (4°.

Crystal structures of 2,2′-bipyridin-1-ium 1,1,3,3-tetracyano-2-ethoxyprop-2-en-1-ide and bis(2,2′-bipyridin-1-ium 1,1,3,3-tetracyano-2-(dicyanomethylenepropane-1,3-diide

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Zouaoui Setifi

2015-05-01

Full Text Available In 2,2′-bipyridin-1-ium 1,1,3,3-tetracyano-2-ethoxyprop-2-en-1-ide, C10H9N2+·C9H5N4O−, (I, the ethyl group in the anion is disordered over two sets of atomic sites with occupancies 0.634 (9 and 0.366 (9, and the dihedral angle between the ring planes in the cation is 2.11 (7°. The two independent C(CN2 groups in the anion make dihedral angles of 10.60 (6 and 12.44 (4° with the central propenide unit, and the bond distances in the anion provide evidence for extensive electronic delocalization. In bis(2,2′-bipyridin-1-ium 1,1,3,3-tetracyano-2-(dicyanomethylenepropane-1,3-diide [alternative name bis(2,2′-bipyridin-1-ium tris(dicyanomethylenemethanediide], 2C10H9N2+·C10N62− (II, the dihedral angles between the ring planes in the two independent cations are 7.7 (2 and 10.92 (17°. The anion exhibits approximate C3 symmetry, consistent with extensive electronic delocalization, and the three independent C(CN2 groups make dihedral angles of 23.8 (2, 27.0 (3 and 27.4 (2° with the central plane. The ions in (I are linked by an N—H...N hydrogen bond and the resulting ion pairs are linked by two independent C—H...N hydrogen bonds, forming a ribbon containing alternating R44(18 and R44(26 rings, where both ring types are centrosymmetric. The ions in (II are linked by two independent N—H...N hydrogen bonds and the resulting ion triplets are linked by a C—H...N hydrogen bond, forming a C21(7 chain containing anions and only one type of cation, with the other cation linked to the chain by a further C—H...N hydrogen bond.

1,3-Di-4-pyridylpropane–4,4′-oxydibenzoic acid (1/1

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Hirofumi Hinode

2008-12-01

Full Text Available The hydrothermal reaction of Cd(NO32·4H2O, 1,3-di-4-pyridylpropane (BPP and 4,4′-oxydibenzoic acid (OBA led to the formation of the title compound, C13H14N2·C14H10O5. The asymmetric unit consists of one molecule of OBA and one of BPP. In the OBA molecule, one COOH group is nearly planar with its attached benzene ring [dihedral angle = 0.9 (1°], while the other COOH group is slightly twisted with a dihedral angle of 10.8 (3°. The carboxyl groups form strong intermolecular O—H...N hydrogen bonds with N atoms of the pyridine rings in BPP, linking the molecules into zigzag chains.

Improved validation of IDP ensembles by one-bond Cα–Hα scalar couplings

Energy Technology Data Exchange (ETDEWEB)

Gapsys, Vytautas [Max Planck Institute for Biophysical Chemistry, Computational Biomolecular Dynamics Group (Germany); Narayanan, Raghavendran L.; Xiang, ShengQi [Max Planck Institute for Biophysical Chemistry, Department for NMR-Based Structural Biology (Germany); Groot, Bert L. de [Max Planck Institute for Biophysical Chemistry, Computational Biomolecular Dynamics Group (Germany); Zweckstetter, Markus, E-mail: markus.zweckstetter@dzne.de [Max Planck Institute for Biophysical Chemistry, Department for NMR-Based Structural Biology (Germany)

2015-11-15

Intrinsically disordered proteins (IDPs) are best described by ensembles of conformations and a variety of approaches have been developed to determine IDP ensembles. Because of the large number of conformations, however, cross-validation of the determined ensembles by independent experimental data is crucial. The {sup 1}J{sub CαHα} coupling constant is particularly suited for cross-validation, because it has a large magnitude and mostly depends on the often less accessible dihedral angle ψ. Here, we reinvestigated the connection between {sup 1}J{sub CαHα} values and protein backbone dihedral angles. We show that accurate amino-acid specific random coil values of the {sup 1}J{sub CαHα} coupling constant, in combination with a reparameterized empirical Karplus-type equation, allow for reliable cross-validation of molecular ensembles of IDPs.

3,3′-Bis(quinolin-8-yl-1,1′-[4,4′-methylenebis(4,1-phenylene]diurea

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Avijit Pramanik

2012-01-01

Full Text Available The title compound, C33H26N6O2, contains two 3-(quinolin-8-ylurea groups linked to a diphenylmethane. The asymmetric unit contains two molecules, A and B. Each quinoline plane is essentially parallel to the attached urea unit [dihedral angles = 8.97 (18 and 8.81 (19 in molecule A and 18.47 (18 and 4.09 (19° in molecule B]. The two benzene rings are twisted, making dihedral angles of 81.36 (8° in A and 87.20 (9° in B. The molecular structures are stabilized by intramolecular N—H...N hydrogen bonds. In the crystal, each urea O atom is involved in two N—H...O hydrogen bonds, generating two interpenetrating three-dimensional sets of molecules.

3,4-Dimethoxy-N-(3-nitrobenzylideneaniline

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Ali Asghar Jarrahpour

2008-11-01

Full Text Available The title compound, C15H14N2O4, has two crystallographically independent molecules in the asymmetric unit. In both molecules, the nitro and the two methoxy substituents are coplanar with the benzene rings to which they are attached. The benzene rings are nearly coplanar, with dihedral angles between the two benzene rings of 10.39 (8 and 5.95 (8° in the two molecules. The two independent molecules in the asymmetric unit are rotated with respect to each other such that the dihedral angles between equivalent benzene rings are 49.11 (8 and 63.93 (8°. In the crystal structure, intermolecular C—H...O hydrogen-bond contacts and a weak C—H...π interaction are observed.

4-Hydroxy-3-methoxybenzaldehyde–nicotinamide (1/1

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Fiona N.-F. How

2011-12-01

Full Text Available In the title compound, C6H6N2O·C8H8O3, an equimolar co-crystal of nicotinamide and vanillin, the aromatic ring and the amide fragment of the nicotinamide molecule make a dihedral angle of 32.6 (2°. The vanillin molecule is almost planar, with an r.m.s. deviation for all non-H atoms of 0.0094 Å. The vaniline and nicotinamide aromatic rings are nearly coplanar, the dihedral angle between them being 3.20 (9°. In the crystal, the two components are linked through N—H...O and O—H...N hydrogen bonds into chains along the a axis. The chains are connected via C—H...O interactions, forming a three-dimensional polymeric structure.

2,6-Diphenyl-4-(2-thienyl-1,4-dihydropyridine-3,5-dicarbonitrile

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Xiao-Tong Zhu

2009-09-01

Full Text Available The asymmetric unit of the title compound, C23H15N3S, contains two crystallographically independent molecules. The pyridine rings adopt envelope conformations. The thiophene rings are oriented at dihedral angles of 77.97 (4/53.53 (4 and 78.44 (4/57.11 (4° with respect to the phenyl rings, while the dihedral angles between the phenyl rings are 48.51 (4 and 44.49 (4°. In the crystal structure, intermolecular N—H...N hydrogen bonds link the molecules into chains along the c axis. The S, C and H atoms of one of the thiophene rings are disordered over two orientations, with occupancy ratios of 0.314 (15:0.686 (15.

Crystal structures of salen-type ligands 2-[(1E-({1-(3-chlorophenyl-2-[(E-(2-hydroxybenzylideneamino]propyl}iminomethyl]phenol and 2-[(1E-({1-(4-chlorophenyl-2-[(E-(2-hydroxybenzylideneamino]propyl}iminomethyl]phenol

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A. Gayathri

2017-12-01

Full Text Available The title compounds, C23H21ClN2O2, differ from each other only by the position of the Cl atom on the corresponding benzene ring: meta relative to the central sp3 C atom for (I and para for (II. In (I, the hydroxyphenyl rings are almost parallel, the dihedral angle between the mean planes being 9.2 (2°, but in (II, the relative position of the ring is different, characterized by a dihedral angle of 48.5 (1°. Compound (I features intramolecular O—H...N and intermolecular C—H...O hydrogen bonds, while in (II, intramolecular O—H...N, C—H...N hydrogen bonds and weak intermolecular C—H...π interactions are observed. Compound (I was refined as an inversion twin.

The Potential of Forest Biomass Inversion Based on Vegetation Indices Using Multi-Angle CHRIS/PROBA Data

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Qiang Wang

2016-10-01

Full Text Available Multi-angle remote sensing can either be regarded as an added source of uncertainty for variable retrieval, or as a source of additional information, which enhances variable retrieval compared to traditional single-angle observation. However, the magnitude of these angular and band effects for forest structure parameters is difficult to quantify. We used the Discrete Anisotropic Radiative Transfer (DART model and the Zelig model to simulate the forest canopy Bidirectional Reflectance Distribution Factor (BRDF in order to build a look-up table, and eight vegetation indices were used to assess the relationship between BRDF and forest biomass in order to find the sensitive angles and bands. Further, the European Space Agency (ESA mission, Compact High Resolution Imaging Spectrometer onboard the Project for On-board Autonomy (CHRIS-PROBA and field sample measurements, were selected to test the angular and band effects on forest biomass retrieval. The results showed that the off-nadir vegetation indices could predict the forest biomass more accurately than the nadir. Additionally, we found that the viewing angle effect is more important, but the band effect could not be ignored, and the sensitive angles for extracting forest biomass are greater viewing angles, especially around the hot and dark spot directions. This work highlighted the combination of angles and bands, and found a new index based on the traditional vegetation index, Atmospherically Resistant Vegetation Index (ARVI, which is calculated by combining sensitive angles and sensitive bands, such as blue band 490 nm/−55°, green band 530 nm/55°, and the red band 697 nm/55°, and the new index was tested to improve the accuracy of forest biomass retrieval. This is a step forward in multi-angle remote sensing applications for mining the hidden relationship between BRDF and forest structure information, in order to increase the utilization efficiency of remote sensing data.

Closing Gaps in Geometrically Frustrated Symmetric Clusters: Local Equivalence between Discrete Curvature and Twist Transformations

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Fang Fang

2018-05-01

Full Text Available In geometrically frustrated clusters of polyhedra, gaps between faces can be closed without distorting the polyhedra by the long established method of discrete curvature, which consists of curving the space into a fourth dimension, resulting in a dihedral angle at the joint between polyhedra in 4D. An alternative method—the twist method—has been recently suggested for a particular case, whereby the gaps are closed by twisting the cluster in 3D, resulting in an angular offset of the faces at the joint between adjacent polyhedral. In this paper, we show the general applicability of the twist method, for local clusters, and present the surprising result that both the required angle of the twist transformation and the consequent angle at the joint are the same, respectively, as the angle of bending to 4D in the discrete curvature and its resulting dihedral angle. The twist is therefore not only isomorphic, but isogonic (in terms of the rotation angles to discrete curvature. Our results apply to local clusters, but in the discussion we offer some justification for the conjecture that the isomorphism between twist and discrete curvature can be extended globally. Furthermore, we present examples for tetrahedral clusters with three-, four-, and fivefold symmetry.

Scattering-angle based filtering of the waveform inversion gradients

KAUST Repository

Alkhalifah, Tariq Ali

2014-01-01

Full waveform inversion (FWI) requires a hierarchical approach to maneuver the complex non-linearity associated with the problem of velocity update. In anisotropic media, the non-linearity becomes far more complex with the potential trade-off between the multiparameter description of the model. A gradient filter helps us in accessing the parts of the gradient that are suitable to combat the potential non-linearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which the low scattering angle of the gradient update is initially muted out in the FWI implementation, in what we may refer to as a scattering angle continuation process. The result is a low wavelength update dominated by the transmission part of the update gradient. In this case, even 10 Hz data can produce vertically near-zero wavenumber updates suitable for a background correction of the model. Relaxing the filtering at a later stage in the FWI implementation allows for smaller scattering angles to contribute higher-resolution information to the model. The benefits of the extended domain based filtering of the gradient is not only it's ability in providing low wavenumber gradients guided by the scattering angle, but also in its potential to provide gradients free of unphysical energy that may correspond to unrealistic scattering angles.

Scattering-angle based filtering of the waveform inversion gradients

KAUST Repository

Alkhalifah, Tariq Ali

2014-11-22

Full waveform inversion (FWI) requires a hierarchical approach to maneuver the complex non-linearity associated with the problem of velocity update. In anisotropic media, the non-linearity becomes far more complex with the potential trade-off between the multiparameter description of the model. A gradient filter helps us in accessing the parts of the gradient that are suitable to combat the potential non-linearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which the low scattering angle of the gradient update is initially muted out in the FWI implementation, in what we may refer to as a scattering angle continuation process. The result is a low wavelength update dominated by the transmission part of the update gradient. In this case, even 10 Hz data can produce vertically near-zero wavenumber updates suitable for a background correction of the model. Relaxing the filtering at a later stage in the FWI implementation allows for smaller scattering angles to contribute higher-resolution information to the model. The benefits of the extended domain based filtering of the gradient is not only it\\'s ability in providing low wavenumber gradients guided by the scattering angle, but also in its potential to provide gradients free of unphysical energy that may correspond to unrealistic scattering angles.

Effect of laser peripheral iridotomy on anterior chamber angle anatomy in primary angle closure spectrum eyes

Science.gov (United States)

Kansara, Seema; Blieden, Lauren S.; Chuang, Alice Z.; Baker, Laura A.; Bell, Nicholas P.; Mankiewicz, Kimberly A.; Feldman, Robert M.

2015-01-01

Purpose To evaluate the change in trabecular-iris circumference volume (TICV) after laser peripheral iridotomy (LPI) in primary angle closure (PAC) spectrum eyes Patients and Methods Forty-two chronic PAC spectrum eyes from 24 patients were enrolled. Eyes with anterior chamber abnormalities affecting angle measurement were excluded. Intraocular pressure, slit lamp exam, and gonioscopy were recorded at each visit. Anterior segment optical coherence tomography (ASOCT) with 3D mode angle analysis scans were taken with the CASIA SS-1000 (Tomey Corp., Nagoya, Japan) before and after LPI. Forty-two pre-LPI ASOCT scans and 34 post-LPI ASOCT scans were analyzed using the Anterior Chamber Analysis and Interpretation (ACAI, Houston, TX) software. A mixed-effect model analysis was used to compare the trabecular-iris space area (TISA) changes among 4 quadrants, as well as to identify potential factors affecting TICV. Results There was a significant increase in all average angle parameters after LPI (TISA500, TISA750, TICV500, and TICV750). The magnitude of change in TISA500 in the superior angle was significantly less than the other angles. The changes in TICV500 and TICV750 were not associated with any demographic or ocular characteristics. Conclusion TICV is a useful parameter to quantitatively measure the effectiveness of LPI in the treatment of eyes with PAC spectrum disease. PMID:26066504

Equilibrium contact angle or the most-stable contact angle?

Science.gov (United States)

Montes Ruiz-Cabello, F J; Rodríguez-Valverde, M A; Cabrerizo-Vílchez, M A

2014-04-01

It is well-established that the equilibrium contact angle in a thermodynamic framework is an "unattainable" contact angle. Instead, the most-stable contact angle obtained from mechanical stimuli of the system is indeed experimentally accessible. Monitoring the susceptibility of a sessile drop to a mechanical stimulus enables to identify the most stable drop configuration within the practical range of contact angle hysteresis. Two different stimuli may be used with sessile drops: mechanical vibration and tilting. The most stable drop against vibration should reveal the changeless contact angle but against the gravity force, it should reveal the highest resistance to slide down. After the corresponding mechanical stimulus, once the excited drop configuration is examined, the focus will be on the contact angle of the initial drop configuration. This methodology needs to map significantly the static drop configurations with different stable contact angles. The most-stable contact angle, together with the advancing and receding contact angles, completes the description of physically realizable configurations of a solid-liquid system. Since the most-stable contact angle is energetically significant, it may be used in the Wenzel, Cassie or Cassie-Baxter equations accordingly or for the surface energy evaluation. © 2013 Elsevier B.V. All rights reserved.

Phase transition in polypeptides: a step towards the understanding of protein folding

DEFF Research Database (Denmark)

Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.

2006-01-01

We present a formalism which turns out to be very successful in the description of the polypeptide folding. We consider this process as a first-order phase transition and develop a theory which is free of model parameters and is based solely on fundamental physical principles. It describes...... essential thermodynamical properties of the system such as heat capacity, the phase transition temperature and others from the analysis of the polypeptide potential energy surface calculated within ab initio density functional theory and parameterized by two dihedral angles. This problem is viewed...

N,N′-Bis[3,5-bis(2,6-diisopropylphenylphenyl]butane-2,3-diimine

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Tracy L. Lohr

2011-09-01

Full Text Available The title molecule, C64H80N2, lies on an inversion center wherein the central butanediimine fragment [N=C(Me—C(Me=N] is essentially planar [maximum deviation = 0.002 (2 Å] and its mean plane forms a dihedral of 70.88 (10° with the attached benzene ring. In the symmetry-unique part of the molecule, the dihedral angles between the benzene ring bonded to the N atom and the other two benzene rings are 89.61 (6 and 82.77 (6°.

Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial.

Science.gov (United States)

Jiang, Yuzhen; Chang, Dolly S; Zhu, Haogang; Khawaja, Anthony P; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M; He, Mingguang; Friedman, David S; Foster, Paul J

2014-09-01

To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Longitudinal cohort study. Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (Pgonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001). Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. Copyright © 2014 American Academy of Ophthalmology. Published by

The influence of flip angle on the magic angle effect

International Nuclear Information System (INIS)

Zurlo, J.V.; Blacksin, M.F.; Karimi, S.

2000-01-01

Objective. To assess the impact of flip angle with gradient sequences on the ''magic angle effect''. We characterized the magic angle effect in various gradient echo sequences and compared the signal- to-noise ratios present on these sequences with the signal-to-noise ratios of spin echo sequences.Design. Ten normal healthy volunteers were positioned such that the flexor hallucis longus tendon remained at approximately at 55 to the main magnetic field (the magic angle). The tendon was imaged by a conventional spin echo T1- and T2-weighted techniques and by a series of gradient techniques. Gradient sequences were altered by both TE and flip angle. Signal-to-noise measurements were obtained at segments of the flexor hallucis longus tendon demonstrating the magic angle effect to quantify the artifact. Signal-to-noise measurements were compared and statistical analysis performed. Similar measurements were taken of the anterior tibialis tendon as an internal control.Results and conclusions. We demonstrated the magic angle effect on all the gradient sequences. The intensity of the artifact was affected by both the TE and flip angle. Low TE values and a high flip angle demonstrated the greatest magic angle effect. At TE values less than 30 ms, a high flip angle will markedly increase the magic angle effect. (orig.)

(E-4-Chloro-N-(2,4,6-trimethylbenzylideneaniline

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Ying Guo

2011-08-01

Full Text Available In the title compound, C16H16ClN, the dihedral angle between the benzene rings is 24.61 (13°. In the crystal, only van der Waals interactions occur between neighbouring molecules.

tert-Butyl 6-bromo-1,4-dimethyl-9H-carbazole-9-carboxylate

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Jean-François Lohier

2010-08-01

Full Text Available The title compound, C19H20BrNO2, consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7 and 4.86 (7° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7. The crystal structure is determined mainly by intramolecular C—H...O and intermolecular π–π interactions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-butoxycarbonyl group on the carbazole N atom and the intramolecular hydrogen bond induce a particular conformation of the exocyclic N—C bond within the molecule.

5-Bromo-2-[5-(4-nitrophenyl-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]pyrimidine

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B. Kalluraya

2009-12-01

Full Text Available In the title pyrazoline compound, C19H14BrN5O2, the essentially planar pyrazoline and pyrimidine rings [maximum deviations = 0.013 (1 and 0.009 (1 Å, respectively] are inclined slightly to one another, making a dihedral angle of 10.81 (10°. The nitrobenzene unit is almost perpendicular to the attached pyrazoline ring, as indicated by the dihedral angle of 84.61 (8°. In the crystal structure, intermolecular C—H...N contacts link the molecules into dimers in an antiparallel manner. These dimers are further linked into one-dimensional chains along the b axis via C—H...O contacts. The crystal structure is consolidated by three different intermolecular π–π interactions [range of centroid–centroid distances = 3.5160 (11–3.6912 (11 Å].

Ethyl 2-{3-[(2-chloro-1,3-thiazol-5-ylmethyl]-4-nitroimino-1,3,5-triazinan-1-yl}acetate

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Chuan-wen Sun

2010-06-01

Full Text Available In the title compound, C11H15ClN6O4S, which belongs to the neonicotinoid class of insecticidally active heterocyclic compounds, the six-membered triazine ring adopts an opened envolope conformation. The planar nitro imine group [dihedral angle between nitro and imine groups = 1.07 (7°] and the thiazole ring are oriented at a dihedral angle of 69.62 (8°. A classical intramolecular N—H...O hydrogen bond is found in the molecular structure. Moreover, one classical intermolecular N—H...N and four non-classical C—H...O and C—H...N hydrogen bonds are also present in the crystal structure. Besides intermolecular hydrogen bonds, the Cl atom forms an intermolecular short contact [3.020 (2 Å] with one of the nitro O atoms.

4-(4-Chlorophenyl-6-(methylsulfanylpyrimidin-2-amine

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Qi-Hua Zhao

2009-08-01

Full Text Available In the title compound, C11H10ClN3S, the dihedral angle between the benzene and pyrimidine rings is 3.99 (4°. In the crystal, intermolecular N—H...N hydrogen bonds link the molecules into ribbons of R22(8 rings parallel to [100]. Weak C—H...S contacts connect adjacent ribbons into a two-dimensional undulating layer-like structure extending parallel to (110. The benzene and pyrimidine rings of adjacent molecules have the offset face-to-face π–π stacking interactions in a zigzag fashion along the c axis, with perpendicular ring distances of 3.463 and 3.639 Å, and a dihedral angle between the planes of 3.99< (2°. The distance between the ring centroids is 4.420 (2 Å.

2-Ethoxy-4-(4-methylphenyl-6-phenylpyridine-3-carbonitrile

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Shaaban K. Mohamed

2012-08-01

Full Text Available The title compound, C21H18N2O, crystallized with two independent molecules (A and B in the asymmetric unit. In molecule A, the central pyridine ring forms dihedral angles of 14.55 (13 and 39.14 (12° with the terminal phenyl and benzene rings, respectively. The latter rings make a dihedral angle of 33.06 (13° with each other. The corresponding values for molecule B are 26.86 (13, 41.82 (12 and 38.99 (13°, respectively. In the crystal, the B molecules are linked via a pair of weak C—H...N hydrogen bonds, forming inversion dimers. In addition, C—H...π interactions and π–π [centroid–centroid distances = 3.5056 (16 and 3.8569 (17 Å] stacking interactions are observed.

1,3,5-Tri-p-tolylpentane-1,5-diol

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A. Thiruvalluvar

2014-02-01

Full Text Available In the title compound, C26H30O2, the central benzene ring forms dihedral angles of 14.85 (15 and 28.17 (14° with the terminal benzene rings. The dihedral angle between the terminal benzene rings is 32.14 (13°. The crystal packing exhibits two strong intermolecular O—H...O hydrogen bonds, forming directed four-membered co-operative rings. A region of disordered electron density, most probably disordered ethyl acetate solvent molecules, occupying voids of ca 519 Å3 for an electron count of 59, was treated using the SQUEEZE routine in PLATON [Spek (2009. Acta Cryst. D65, 148–155]. Their formula mass and unit-cell characteristics were not taken into account during refinement. The structure was refined as an inversion twin [absolute structure parameter = −0.3 (4].

(E-1-(4-Aminophenyl-3-(naphthalen-2-ylprop-2-en-1-one

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Thawanrat Kobkeatthawin

2011-05-01

Full Text Available The molecule of the title chalcone derivative, C19H15NO, exists in a trans configuration with respect to the C=C double bond. The molecule is slightly twisted with a dihedral angle of 6.12 (12° between the benzene ring and the naphthalene ring system. The prop-2-en-1-one bridge is nearly planar, with an r.m.s. deviation of 0.0194 (2, and makes dihedral angles of 8.05 (19 and 11.47 (18° with the benzene ring and the naphthalene ring system, respectively. In the crystal, molecules are linked by N—H...O hydrogen bonds into chains along the b axis. Weak N—H...π and C—H...π interactions and a short N...O contact [2.974 (4 Å] are also observed.

(3R,4R,4aS,7aR,12bS-3-Cyclopropylmethyl-4a,9-dihydroxy-3-methyl-7-oxo-2,3,4,4a,5,6,7,7a-octahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-3-ium bromide

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Xiangfeng Chen

2012-02-01

Full Text Available The title compound, C21H26NO4+·Br−, also known as R-methylnaltrexone (MNTX bromide, is a selective peripherally acting μ-opioid receptor antagonist with a oroxymorphone skeleton, synthesized by hydroxyl protection, N-methylation, deprotection and anion exchange of naltrexone. It comprises a five-ring system A/B/C/D/E. Rings C and E adopt distorted chair conformations, whereas ring D is in half-chair conformation. The C/E ring junctions are trans fused. The dihedral angle between rings D and E is 82.3 (1°, while the dihedral angles between the planes of rings C and A, and rings D and E are respectively 81.7 (1, 75.9 (1 and 12.2 (1°. In the crystal, molecules are linked by O—H...Br hydrogen bonds.

Crystal structure of 3-benzamido-1-(4-nitrobenzylquinolinium trifluoromethanesulfonate

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Mariana Nicolas-Gomez

2016-05-01

Full Text Available In the title compound, C23H18N3O3+·CF3SO3−, the asymmetric unit contains two crystallographically independent organic cations with similar conformations. Each cation shows a moderate distortion between the planes of the amide groups and the quinolinium rings with dihedral angles of 14.90 (2 and 31.66 (2°. The quinolinium and phenyl rings are slightly twisted with respect to each other at dihedral angles of 6.99 (4 and 8.54 (4°. The trifluoromethanesulfonate anions are linked to the organic cations via N—H...O hydrogen-bonding interactions involving the NH amide groups. In the crystal, the organic cations are linked by weak C—H...O(nitro group interactions into supramolecular chains propagating along the b-axis direction.

Modeling the intermolecular interactions: molecular structure of N-3-hydroxyphenyl-4-methoxybenzamide.

Science.gov (United States)

Karabulut, Sedat; Namli, Hilmi; Kurtaran, Raif; Yildirim, Leyla Tatar; Leszczynski, Jerzy

2014-03-01

The title compound, N-3-hydroxyphenyl-4-methoxybenzamide (3) was prepared by the acylation reaction of 3-aminophenol (1) and 4-metoxybenzoylchloride (2) in THF and characterized by ¹H NMR, ¹³C NMR and elemental analysis. Molecular structure of the crystal was determined by single crystal X-ray diffraction and DFT calculations. 3 crystallizes in monoclinic P2₁/c space group. The influence of intermolecular interactions (dimerization and crystal packing) on molecular geometry has been evaluated by calculations performed for three different models; monomer (3), dimer (4) and dimer with added unit cell contacts (5). Molecular structure of 3, 4 and 5 was optimized by applying B3LYP method with 6-31G+(d,p) basis set in gas phase and compared with X-ray crystallographic data including bond lengths, bond angles and selected dihedral angles. It has been concluded that although the crystal packing and dimerization have a minor effect on bond lengths and angles, however, these interactions are important for the dihedral angles and the rotational conformation of aromatic rings. Copyright © 2013 Elsevier Inc. All rights reserved.

Thermal degradation kinetics and solid state, temperature ...

Indian Academy of Sciences (India)

WINTEC

proceeds due to the oxidation of sulphur atom in the ring to sulphoxide, for the .... grain boundaries etc. Electrical properties ... The spatial orientation in phenothiazine ... atom points outside with respect to the dihedral angle. The two forms are ...

Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects

Science.gov (United States)

Jiang, Yuzhen; Chang, Dolly S.; Zhu, Haogang; Khawaja, Anthony P.; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M.

2015-01-01

Objective To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Design Longitudinal cohort study. Participants Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Methods Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Main Outcome Measures Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. Results No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (Pgonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1.3–2.0) in untreated eyes (P<0.001). Conclusions Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the

Input vector optimization of feed-forward neural networks for fitting ab initio potential-energy databases

Science.gov (United States)

Malshe, M.; Raff, L. M.; Hagan, M.; Bukkapatnam, S.; Komanduri, R.

2010-05-01

The variation in the fitting accuracy of neural networks (NNs) when used to fit databases comprising potential energies obtained from ab initio electronic structure calculations is investigated as a function of the number and nature of the elements employed in the input vector to the NN. Ab initio databases for H2O2, HONO, Si5, and H2CCHBr were employed in the investigations. These systems were chosen so as to include four-, five-, and six-body systems containing first, second, third, and fourth row elements with a wide variety of chemical bonding and whose conformations cover a wide range of structures that occur under high-energy machining conditions and in chemical reactions involving cis-trans isomerizations, six different types of two-center bond ruptures, and two different three-center dissociation reactions. The ab initio databases for these systems were obtained using density functional theory/B3LYP, MP2, and MP4 methods with extended basis sets. A total of 31 input vectors were investigated. In each case, the elements of the input vector were chosen from interatomic distances, inverse powers of the interatomic distance, three-body angles, and dihedral angles. Both redundant and nonredundant input vectors were investigated. The results show that among all the input vectors investigated, the set employed in the Z-matrix specification of the molecular configurations in the electronic structure calculations gave the lowest NN fitting accuracy for both Si5 and vinyl bromide. The underlying reason for this result appears to be the discontinuity present in the dihedral angle for planar geometries. The use of trigometric functions of the angles as input elements produced significantly improved fitting accuracy as this choice eliminates the discontinuity. The most accurate fitting was obtained when the elements of the input vector were taken to have the form Rij-n, where the Rij are the interatomic distances. When the Levenberg-Marquardt procedure was modified

N-(4-Methoxyphenyl-4-methylbenzenesulfonamide

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Islam Ullah Khan

2011-01-01

Full Text Available In the title compound, C14H15NO3S, the dihedral angle between the aromatic rings is 59.39 (14° and the C—S—N—C torsion angle is −71.4 (2°. In the crystal, a supramolecular chain running along the b axis with a C(4 graph set is formed via N—H...O hydrogen bonds.

Angled shots onto body armour using 9 mm ammunition: the effect on potential blunt injury.

Science.gov (United States)

Lyall, Alison; Carr, D J; Lankester, C; Malbon, C

2017-02-01

Some military specialists wear body armour that is more similar to police armour and provides protection from ammunition fired from pistols. During ballistic testing, these armours are mounted on a standardised type of modelling clay and the back face signature (BFS; depth of depression) formed as a result of the non-perforating impact event on to the armour is measured. This study investigated the effect of impact angle on the BFS and on the deformation of the bullet. Two commonly worn types of armour (HG1/A+KR1 and HG1+KR1) were considered that provide protection from pistol ammunition and sharp weapons. Armours were tested against two types of pistol ammunition (9 mm full metal jacket and 9 mm hollow point) at eight different impact angles (0°, 15°, 30°, 45°, 60°, 70°, 75° and 80°). Increased impact angles resulted in smaller BFSs. Impact angle also affected whether bullets were retained in the armour; as the impact angle increased, the probability of a round exiting the side of the armour increased. Bullet deformation was affected by impact angle. Understanding the deformation of bullets may assist with recreating a shooting incident and interpreting forensic evidence. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

(Z-N-[3-(4-Bromobenzoyl-1,3-thiazolidin-2-ylidene]cyanamide

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Ling Xu

2010-12-01

Full Text Available In the title compound, C11H8BrN3OS, the dihedral angle between the benzene and thiazolidine rings is 63.4 (2°. Intermolecular C—H...N interactions help to stabilize the crystal structure.

1-(3-Fluorophenyl-3-(4-nitrophenylurea

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Mu-Sen Lin

2012-07-01

Full Text Available In the title compound, C13H10FN3O3, the dihedral angle between the fluorophenyl and nitrophenyl ring planes is 6.51 (9°. The crystal structure features N—H...O hydrogen bonds.

Pressure-dependent {sup 13}C chemical shifts in proteins: origins and applications

Energy Technology Data Exchange (ETDEWEB)

Wilton, David J. [University of Sheffield, Department of Molecular Biology and Biotechnology (United Kingdom); Kitahara, Ryo [Ritsumeikan University, College of Pharmaceutical Sciences (Japan); Akasaka, Kazuyuki [Kinki University, Department of Biotechnological Science, School of Biology-Oriented Science and Technology (Japan); Williamson, Mike P. [University of Sheffield, Department of Molecular Biology and Biotechnology (United Kingdom)], E-mail: m.williamson@sheffield.ac.uk

2009-05-15

Pressure-dependent {sup 13}C chemical shifts have been measured for aliphatic carbons in barnase and Protein G. Up to 200 MPa (2 kbar), most shift changes are linear, demonstrating pressure-independent compressibilities. CH{sub 3}, CH{sub 2} and CH carbon shifts change on average by +0.23, -0.09 and -0.18 ppm, respectively, due to a combination of bond shortening and changes in bond angles, the latter matching one explanation for the {gamma}-gauche effect. In addition, there is a residue-specific component, arising from both local compression and conformational change. To assess the relative magnitudes of these effects, residue-specific shift changes for protein G were converted into structural restraints and used to calculate the change in structure with pressure, using a genetic algorithm to convert shift changes into dihedral angle restraints. The results demonstrate that residual {sup 13}C{alpha} shifts are dominated by dihedral angle changes and can be used to calculate structural change, whereas {sup 13}C{beta} shifts retain significant dependence on local compression, making them less useful as structural restraints.

The paediatric Bohler's angle and crucial angle of Gissane: a case series

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Crawford Haemish A

2011-01-01

Full Text Available Abstract Background Bohler's angle and the crucial angle of Gissane can be used to assess calcaneal fractures. While the normal adult values of these angles are widely known, the normal paediatric values have not yet been established. Our aim is to investigate Bohler's angle and the crucial angle of Gissane in a paediatric population and establish normal paediatric reference values. Method We measured Bohler's angle and the crucial angle of Gissane using normal plain ankle radiographs of 763 patients from birth to 14 years of age completed over a five year period from July 2003 to June 2008. Results In our paediatric study group, the mean Bohler's angle was 35.2 degrees and the mean crucial angle of Gissane was 111.3 degrees. In an adult comparison group, the mean Bohler's angle was 39.2 degrees and the mean crucial angle of Gissane was 113.8 degrees. The differences in Bohler's angle and the crucial angle of Gissane between these two groups were statistically significant. Conclusion We have presented the normal values of Bohler's angle and the crucial angle of Gissane in a paediatric population. These values may provide a useful comparison to assist with the management of the paediatric calcaneal fracture.

Creation of the {pi} angle standard for the flat angle measurements

Energy Technology Data Exchange (ETDEWEB)

Giniotis, V; Rybokas, M, E-mail: gi@ap.vtu.l, E-mail: MRybokas@gama.l [Department of Information Technologies, Vilnius Gediminas Technical University, Sauletekio al. 11, 10223 Vilnius-40 (Lithuania)

2010-07-01

Angle measurements are based mainly on multiangle prisms - polygons with autocollimators, rotary encoders for high accuracy and circular scales as the standards of the flat angle. Traceability of angle measurements is based on the standard of the plane angle - prism (polygon) calibrated at an appropriate accuracy. Some metrological institutions have established their special test benches (comparators) equipped with circular scales or rotary encoders of high accuracy and polygons with autocollimators for angle calibration purposes. Nevertheless, the standard (etalon) of plane angle - polygon has many restrictions for the transfer of angle unit - radian (rad) and other units of angle. It depends on the number of angles formed by the flat sides of the polygon that is restricted by technological and metrological difficulties related to the production and accuracy determination of the polygon. A possibility to create the standard of the angle equal to {pi} rad or half the circle or the full angle is proposed. It can be created by the circular scale with the rotation axis of very high accuracy and two precision reading instruments, usually, photoelectric microscopes (PM), placed on the opposite sides of the circular scale using the special alignment steps. A great variety of angle units and values can be measured and its traceability ensured by applying the third PM on the scale. Calibration of the circular scale itself and other scale or rotary encoder as well is possible using the proposed method with an implementation of {pi} rad as the primary standard angle. The method proposed enables to assure a traceability of angle measurements at every laboratory having appropriate environment and reading instruments of appropriate accuracy together with a rotary table with the rotation axis of high accuracy - rotation trajectory (runout) being in the range of 0.05 {mu}m. Short information about the multipurpose angle measurement test bench developed is presented.

Unusually large chemical potential shift in a degenerate semiconductor: Angle-resolved photoemission study of SnSe and Na-doped SnSe

Science.gov (United States)

Maeda, M.; Yamamoto, K.; Mizokawa, T.; Saini, N. L.; Arita, M.; Namatame, H.; Taniguchi, M.; Tan, G.; Zhao, L. D.; Kanatzidis, M. G.

2018-03-01

We have studied the electronic structure of SnSe and Na-doped SnSe by means of angle-resolved photoemission spectroscopy. The valence-band top reaches the Fermi level by the Na doping, indicating that Na-doped SnSe can be viewed as a degenerate semiconductor. However, in the Na-doped system, the chemical potential shift with temperature is unexpectedly large and is apparently inconsistent with the degenerate semiconductor picture. The large chemical potential shift and anomalous spectral shape are key ingredients for an understanding of the novel metallic state with the large thermoelectric performance in Na-doped SnSe.

Glaucoma, Open-Angle

Science.gov (United States)

... Home » Statistics and Data » Glaucoma, Open-angle Listen Glaucoma, Open-angle Open-angle Glaucoma Defined In open-angle glaucoma, the fluid passes ... 2010 2010 U.S. Age-Specific Prevalence Rates for Glaucoma by Age and Race/Ethnicity The prevalence of ...

Charge transfer properties of pentacene adsorbed on silver: DFT study

Energy Technology Data Exchange (ETDEWEB)

N, Rekha T.; Rajkumar, Beulah J. M., E-mail: beulah-rajkumar@yahoo.co.in [PG & Research Department of Physics, Lady Doak College, Madurai 625002 (India)

2015-06-24

Charge transfer properties of pentacene adsorbed on silver is investigated using DFT methods. Optimized geometry of pentacene after adsorption on silver indicates distortion in hexagonal structure of the ring close to the silver cluster and deviations in co-planarity of carbon atoms due to the variations in bond angles and dihedral angles. Theoretically simulated absorption spectrum has a symmetric surface plasmon resonance peak around 486nm corresponding to the transfer of charge from HOMO-2 to LUMO. Theoretical SERS confirms the process of adsorption, tilted orientation of pentacene on silver surface and the charge transfers reported. Localization of electron density arising from redistribution of electrostatic potential together with a reduced bandgap of pentacene after adsorption on silver suggests its utility in the design of electro active organic semiconducting devices.

2-Fluoro-5-(4-fluorophenylpyridine

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Fazal Elahi

2012-07-01

Full Text Available In the title compound, C11H7F2N, the fluorobenzene and the 2-fluoropyridine rings are oriented at a dihedral angle of 37.93 (5°. In the crystal, only van der Waals interactions occur.

2-(Biphenyl-4-ylacetic acid (felbinac

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Lynne S. Taylor

2010-10-01

Full Text Available The structure of the title compound, C14H12O2, displays the expected intermolecular hydrogen bonding of the carboxylic acid groups, forming dimers. The dihedral angle between the two aromatic rings is 27.01 (7°.

The influence of erupting lateral teeth on maxillary anterior crowding in two Angle Class I maloclussion cases with high and low angles

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Hiroshi Ueda

2016-01-01

Full Text Available Two cases of anterior crowding, both Skeletal Class I and Angle Class I maloclussion, one being low angle and the other high angle respectively, respectively, were treated and evaluated to ascertain whether or not there is a relationship among disproportionate mesial axial angulation of the maxillary lateral teeth and the Frankfurt Horizontal-Functional Occlusal plane, therefore generating maxillary anterior crowding. Both cases were Japanese boys, the first one aged 9 years 10 months with chief complaint being anterior crowding and the second case aged 7 years and 8 months complaining of inadequate space for satisfying canine eruption. During and after the second stage of orthodontic treatment on both cases, several radiographic analysis were performed to assess treatment progress and retention; from these radiographs, it was noticed among other findings that in the high-angle case, the axial angulations of the maxillary lateral incisors were markedly smaller than in the low-angle case, thus indicating mesial tipping in the upper dental arch. This decreased mesial axial angulation of the lateral teeth observed at high angles may potentially cause maxillary space deficiency.

N′-[Bis(benzylsulfanylmethylidene]-4-methoxybenzohydrazide

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Jerry P. Jasinski

2010-08-01

Full Text Available In the title compound, C23H22N2O2S2, the dihedral angles between the 4-methoxy-substituted phenyl ring and the other two phenyl rings are 84.4 (4 and 77.7 (1°, respectively, while the dihedral angle between the two phenyl rings is 57.5 (2°. The amino group is not involved in an N—H hydrogen bond. The crystal packing is established by intermolecular C—H...O packing interactions involving a relatively rare weak three-center hydrogen bond between the keto O atom and H atoms of the two nearby phenyl rings, which link the molecules into chains running along the a axis. Additional weak intermolecular hydrogen-bond interactions between the 4-methoxy O atom and one of the phenyl rings and provide added stability to the crystal packing.

trans-Diaquabis[2,5-bis(pyridin-2-yl-1,3,4-thiadiazole]cobalt(II bis(tetrafluoridoborate

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Fouad Bentiss

2011-07-01

Full Text Available The bidentate 1,3,4-thiadiazole ligand substituted by two 2-pyridyl rings (denoted L has been found to produce the new monomeric title complex, [Co(C12H8N4S2(H2O2](BF42. The thiadiazole and pyridyl rings surrounding the Co atom are almost coplanar [dihedral angle = 4.35 (7°]. The mean plane defined by these heterocyclic moieties makes a dihedral angle of 18.72 (6° with the non-coordinated pyridyl ring. The Co2+ cation, located at a crystallographic center of symmetry, is bonded to two ligands and two water molecules in a trans configuration in an octahedral environment. The tetrafluoridoborate ions can be regarded as free anions in the crystal lattice. Nevertheless, they are involved in an infinite two-dimensional network along the [010] and [101] directions of O—H...F hydrogen bonds.

Ethyl 13-(4-chlorophenyl-11-methyl-6-oxo-5-phenyl-8-thia-3,4,5,10-tetraazatricyclo[7.4.0.02,7]trideca-1(9,2(7,3,10,12-pentaene-12-carboxylate

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Elham A. Al-Taifi

2016-05-01

Full Text Available In the title molecule, C24H17ClN4O3S, the central tricyclic moiety is twisted slightly, as indicated by the dihedral angles of 4.86 (5 and 0.97 (6°, respectively, between the five-membered ring and the C3N3 and pyridyl rings. Additionally, the chlorobenzene ring makes a dihedral angle of 65.80 (5° with the pyridyl ring. Weak C—H...O, C—Cl...N [3.0239 (13 Å] and π–π stacking interactions [inter-centroid distance between thienyl rings = 3.6994 (8 Å, and between thienyl and pyridyl rings = 3.7074 (8 Å] contribute to the molecular packing. The ethyl group in the ester moiety is disordered over two sets of sites, with the major component having an occupancy of 0.567 (11.

4,4′-[Thiophene-2,5-diylbis(ethyne-2,1-diyl]dibenzonitrile

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Kari Rissanen

2008-04-01

Full Text Available In the solid state, the title compound, C22H10N2S, forms centrosymmetric dimers by pairs of non-classical C—H...S hydrogen bonds linking approximately coplanar molecules. The benzene ring involved in this interaction makes a dihedral angle of only 7.21 (16° with the thiophene ring, while the other benzene ring is twisted somewhat out of the plane, with a dihedral angle of 39.58 (9°. The hydrogen-bonded dimers stack on top of each other with an interplanar spacing of 3.44 Å. C—H...N hydrogen bonds link together stacks that run in approximately perpendicular directions. Each molecule thus interacts with 12 adjacent molecules, five of them approaching closer than the sum of the van der Waals radii for the relevant atoms. Optimization of the inter-stack contacts contributes to the non-planarity of the molecule.

Crystal structure of (E-4-{2-[4-(allyloxyphenyl]diazenyl}benzoic acid

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Md. Lutfor Rahman

2014-12-01

Full Text Available The title compound, C16H14N2O3, has an E conformation about the azobenzene [—N=N– = 1.2481 (16 Å] linkage. The benzene rings are almost coplanar [dihedral angle = 1.36 (7°]. The O atoms of the carboxylic acid group are disordered over two sets of sites and were refined with an occupancy ratio of 0.5:0.5. The two disordered components of the carboxylic acid group make dihedral angles of 1.5 (14 and 3.8 (12° with the benzene ring to which they are attached. In the crystal, molecules are linked via pairs of O—H...O hydrogen bonds, forming inversion dimers. The dimers are connected via C—H...O hydrogen bonds, forming ribbons lying parallel to [120]. These ribbons are linked via C—H...π interactions, forming slabs parallel to (001.

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazocine-6,12-dione acetic acid hemisolvate

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Najat Abbassi

2013-04-01

Full Text Available The molecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12°. In the crystal, the molecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent molecule by non-classical O—H...O and C—H...O hydrogen bonds. Two half-occupied acetic acid solvent molecules are disordered at the same site and linked by a center of symmetry.

Crystal structure of 3-{5-[3-(4-fluorophenyl-1-isopropyl-1H-indol-2-yl]-1H-pyrazol-1-yl}indolin-2-one ethanol monosolvate

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Md. Lutfor Rahman

2016-03-01

Full Text Available The title indolin-2-one compound, C28H23FN4O·C2H6O, crystallizes as a 1:1 ethanol solvate. The ethanol molecule is disordered over two positions with refined site occupancies of 0.560 (14 and 0.440 (14. The pyrazole ring makes dihedral angles of 84.16 (10 and 85.33 (9° with the indolin-2-one and indole rings, respectively, whereas the dihedral angle between indolin-2-one and indole rings is 57.30 (7°. In the crystal, the components are linked by N—H...O and O—H...O hydrogen bonds, forming an inversion molecule–solvate 2:2 dimer with R44(12 ring motifs. The crystal structure is consolidated by π–π interaction between pairs of inversion-related indolin-2-one rings [interplanar spacing = 3.599 (2 Å].

N-(2-Chlorophenyl-2-methylbenzamide

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B. Thimme Gowda

2008-08-01

Full Text Available In the structure of the title compound (N2CP2MBA, C14H12ClNO, the conformations of the N—H and C=O bonds are trans to each other. Furthermore, the conformation of the N—H bond is syn to the ortho-chloro group in the aniline ring and the C=O bond is syn to the ortho-methyl substituent in the benzoyl ring, similar to what is observed in 2-chloro-N-(2-chlorophenylbenzamide and 2-methyl-N-phenylbenzamide. The amide group makes almost the same dihedral angles of 41.2 (14 and 42.2 (13° with the aniline and benzoyl rings, respectively, while the dihedral angle between the benzoyl and aniline rings is only 7.4 (3°. The molecules in N2CP2MBA are packed into chains through N—H...O hydrogen bonds.

2,2′-Dimethyl-1,1′-[2,2-bis(bromomethylpropane-1,3-diyl]dibenzimidazole hemihydrate

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Yong-Sheng Yan

2012-03-01

Full Text Available The title compound, C21H22Br2N4·0.5H2O, contains two benzimidazole groups which may provide two potential coordination nodes for the construction of metal–organic frameworks. The mean planes of the two imidazole groups are almost perpendicular, with a dihedral angle of 83.05 (2°, and adjacent molecules are linked into a one-dimensional chain by π–π stacking interactions between imidazole groups of different molecules [centroid-to-centroid distances of 3.834 (2 and 3.522 (2 Å].

Improved estimation of leaf area index and leaf chlorophyll content of a potato crop using multi-angle spectral data - potential of unmanned aerial vehicle imagery

Science.gov (United States)

Roosjen, Peter P. J.; Brede, Benjamin; Suomalainen, Juha M.; Bartholomeus, Harm M.; Kooistra, Lammert; Clevers, Jan G. P. W.

2018-04-01

In addition to single-angle reflectance data, multi-angular observations can be used as an additional information source for the retrieval of properties of an observed target surface. In this paper, we studied the potential of multi-angular reflectance data for the improvement of leaf area index (LAI) and leaf chlorophyll content (LCC) estimation by numerical inversion of the PROSAIL model. The potential for improvement of LAI and LCC was evaluated for both measured data and simulated data. The measured data was collected on 19 July 2016 by a frame-camera mounted on an unmanned aerial vehicle (UAV) over a potato field, where eight experimental plots of 30 × 30 m were designed with different fertilization levels. Dozens of viewing angles, covering the hemisphere up to around 30° from nadir, were obtained by a large forward and sideways overlap of collected images. Simultaneously to the UAV flight, in situ measurements of LAI and LCC were performed. Inversion of the PROSAIL model was done based on nadir data and based on multi-angular data collected by the UAV. Inversion based on the multi-angular data performed slightly better than inversion based on nadir data, indicated by the decrease in RMSE from 0.70 to 0.65 m2/m2 for the estimation of LAI, and from 17.35 to 17.29 μg/cm2 for the estimation of LCC, when nadir data were used and when multi-angular data were used, respectively. In addition to inversions based on measured data, we simulated several datasets at different multi-angular configurations and compared the accuracy of the inversions of these datasets with the inversion based on data simulated at nadir position. In general, the results based on simulated (synthetic) data indicated that when more viewing angles, more well distributed viewing angles, and viewing angles up to larger zenith angles were available for inversion, the most accurate estimations were obtained. Interestingly, when using spectra simulated at multi-angular sampling configurations as

Apparent contact angle and contact angle hysteresis on liquid infused surfaces.

Science.gov (United States)

Semprebon, Ciro; McHale, Glen; Kusumaatmaja, Halim

2016-12-21

We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small but finite ridge, which corresponds to an effective line tension term. We also predict contact angle hysteresis on liquid infused surfaces generated by the pinning of the contact lines by the surface corrugations. Our analytical expressions for both the apparent contact angle and contact angle hysteresis can be interpreted as 'weighted sums' between the contact angles of the infusing liquid relative to the droplet and surrounding gas phases, where the weighting coefficients are given by ratios of the fluid surface tensions.

Anomalous and resonance small-angle scattering

International Nuclear Information System (INIS)

Epperson, J.E.; Thiyagarajan, P.

1988-01-01

Significant changes in the small-angle scattered intensity can be induced by making measurements with radiation close to an absorption edge of an appropriate atomic species contained in the sample. These changes can be related quantitatively to the real and imaginary anomalous-dispersion terms for the scattering factor (X-rays) or scattering length (neutrons). The physics inherent in these anomalous-dispersion terms is first discussed before consideration of how they enter the relevant scattering theory. Two major areas of anomalous-scattering research have emerged; macromolecules in solution and unmixing of metallic alloys. Research in each area is reviewed, illustrating both the feasibility and potential of these techniques. All the experimental results reported to date have been obtained with X-rays. However, it is pointed out that the formalism is the same for the analog experiment with neutrons, and a number of suitable isotopes exist which exhibit resonance in an accessible range of energy. Potential applications of resonance small-angle neutron scattering are discussed. (orig.)

Estimates of md-mu and left-angle bar dd right-angle -left-angle bar uu right-angle from QCD sum rules for D and D* isospin mass differences

International Nuclear Information System (INIS)

Eletsky, V.L.; Ioffe, B.L.

1993-01-01

The recent experimental data on D +- D0 and D *+- D*0 mass differences are used as inputs in the QCD sum rules to obtain new estimates on the mass difference of light quarks and on the difference of their condensates: m d -m u =3±1 MeV, left-angle bar dd right-angle -left-angle bar uu right-angle=-(2.5±1)x10 -3 left-angle bar uu right-angle (at a standard normalization point, μ=0.5 GeV)

Scoliosis angle

International Nuclear Information System (INIS)

Marklund, T.

1978-01-01

The most commonly used methods of assessing the scoliotic deviation measure angles that are not clearly defined in relation to the anatomy of the patient. In order to give an anatomic basis for such measurements it is proposed to define the scoliotic deviation as the deviation the vertebral column makes with the sagittal plane. Both the Cobb and the Ferguson angles may be based on this definition. The present methods of measurement are then attempts to measure these angles. If the plane of these angles is parallel to the film, the measurement will be correct. Errors in the measurements may be incurred by the projection. A hypothetical projection, called a 'rectified orthogonal projection', is presented, which correctly represents all scoliotic angles in accordance with these principles. It can be constructed in practice with the aid of a computer and by performing measurements on two projections of the vertebral column; a scoliotic curve can be represented independent of the kyphosis and lordosis. (Auth.)

Automated analysis of angle closure from anterior chamber angle images.

Science.gov (United States)

Baskaran, Mani; Cheng, Jun; Perera, Shamira A; Tun, Tin A; Liu, Jiang; Aung, Tin

2014-10-21

To evaluate a novel software capable of automatically grading angle closure on EyeCam angle images in comparison with manual grading of images, with gonioscopy as the reference standard. In this hospital-based, prospective study, subjects underwent gonioscopy by a single observer, and EyeCam imaging by a different operator. The anterior chamber angle in a quadrant was classified as closed if the posterior trabecular meshwork could not be seen. An eye was classified as having angle closure if there were two or more quadrants of closure. Automated grading of the angle images was performed using customized software. Agreement between the methods was ascertained by κ statistic and comparison of area under receiver operating characteristic curves (AUC). One hundred forty subjects (140 eyes) were included, most of whom were Chinese (102/140, 72.9%) and women (72/140, 51.5%). Angle closure was detected in 61 eyes (43.6%) with gonioscopy in comparison with 59 eyes (42.1%, P = 0.73) using manual grading, and 67 eyes (47.9%, P = 0.24) with automated grading of EyeCam images. The agreement for angle closure diagnosis between gonioscopy and both manual (κ = 0.88; 95% confidence interval [CI), 0.81-0.96) and automated grading of EyeCam images was good (κ = 0.74; 95% CI, 0.63-0.85). The AUC for detecting eyes with gonioscopic angle closure was comparable for manual and automated grading (AUC 0.974 vs. 0.954, P = 0.31) of EyeCam images. Customized software for automated grading of EyeCam angle images was found to have good agreement with gonioscopy. Human observation of the EyeCam images may still be needed to avoid gross misclassification, especially in eyes with extensive angle closure. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

1,3-Bis(4-tert-butylphenyl-4-nitrobutan-1-one

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Dong-Yin Ren

2011-06-01

Full Text Available In the crystal structure of the title compound, C24H31NO3, molecules are connected via C—H...O intermolecular hydrogen bonds, forming dimers. The benzene rings are oriented at a dihedral angle of 29.8 (1°.

Chiral discrimination in biomimetic systems: Phenylalanine

Indian Academy of Sciences (India)

WINTEC

dihedral angle to locate the minimum energy conformation using quantum chemical theory. We com- pared the intermolecular energy surfaces of phenyl alanine molecule in its neutral and zwitterionic state ... sub-units like amino acids in protein remained a puzzle. ... non-bonded and electrostatic interaction between.

Crystal structures of functional building blocks derived from bis(benzo[b]thiophen-2-yl)methane.

Science.gov (United States)

Katzsch, Felix; Gruber, Tobias; Weber, Edwin

2016-09-01

The syntheses of three bis(benzo[b]thiophen-2-yl)methane derivatives, namely bis(benzo[b]thiophen-2-yl)methanone, C17H10OS2, (I), 1,1-bis(benzo[b]thiophen-2-yl)-3-(trimethylsilyl)prop-2-yn-1-ol, C22H20OS2Si, (II), and 1,1-bis(benzo[b]thiophen-2-yl)prop-2-yn-1-ol, C19H12OS2, (III), are described and their crystal structures discussed comparatively. The conformation of ketone (I) and the respective analogues are rather similar for most of the compounds compared. This is true for the interplanar angles, the Caryl-Cbridge-Caryl angles and the dihedral angles. The best resemblance is found for a bioisotere of (I), viz. 2,2'-dinaphthyl ketone, (VII). By way of interest, the crystal packings also reveal similarities between (I) and (VII). In (I), the edge-to-face interactions seen between two napthyl residues in (VII) are substituted by S...π contacts between the benzo[b]thiophen-2-yl units in (I). In the structures of the bis(benzo[b]thiophen-2-yl)methanols, i.e. (II) and (III), the interplanar angles are also quite similar compared with analogues and related active pharmaceutical ingredients (APIs) containing the dithiophen-2-ylmethane scaffold, though the dihedral angles show a larger variability and produce unsymmetrical molecules.

Increasing efficacy of graminicides with a forward angled spray

DEFF Research Database (Denmark)

Jensen, Peter Kryger

2012-01-01

Control of annual grass species with vertically oriented leaves in agricultural crops by application of foliar acting herbicides with conventional hydraulic sprayers can be increased using forward angled nozzles. Changing the spray angle from the normally predominantly vertical spray towards...... an angled spray increases the potential target size of vertically oriented targets. This theory was tested in field experiments from 2005 to 2009 investigating control of three different grass species and a dicotyledonous weed species at early growth stages using foliar acting herbicides. Lolium perenne...... efficacy on L. perenne at early growth stages using nozzles with different spray quality, at different driving speeds and in different wind conditions. Similarly graminicide efficacy was increased when nozzles were angled 60° forward controlling A. myosuroides. Experiments investigating control of the two...

Precise determination of lattice phase shifts and mixing angles

Energy Technology Data Exchange (ETDEWEB)

Lu, Bing-Nan, E-mail: b.lu@fz-juelich.de [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Lähde, Timo A. [Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Lee, Dean [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Meißner, Ulf-G. [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); JARA – High Performance Computing, Forschungszentrum Jülich, D-52425 Jülich (Germany)

2016-09-10

We introduce a general and accurate method for determining lattice phase shifts and mixing angles, which is applicable to arbitrary, non-cubic lattices. Our method combines angular momentum projection, spherical wall boundaries and an adjustable auxiliary potential. This allows us to construct radial lattice wave functions and to determine phase shifts at arbitrary energies. For coupled partial waves, we use a complex-valued auxiliary potential that breaks time-reversal invariance. We benchmark our method using a system of two spin-1/2 particles interacting through a finite-range potential with a strong tensor component. We are able to extract phase shifts and mixing angles for all angular momenta and energies, with precision greater than that of extant methods. We discuss a wide range of applications from nuclear lattice simulations to optical lattice experiments.

ASSESSMENT OF LENS THICKNESS IN ANGLE CLOSURE DISEASE

Directory of Open Access Journals (Sweden)

Nishat Sultana Khayoom

2016-08-01

Full Text Available BACKGROUND Anterior chamber depth and lens thickness have been considered as important biometric determinants in primary angle-closure glaucoma. Patients with primary narrow angle may be classified as a primary angle closure suspect (PACS, or as having primary angle closure (PAC or primary angle closure glaucoma (PACG. 23.9% of patients with primary angle closure disease are in India, which highlights the importance of understanding the disease, its natural history, and its underlying pathophysiology, so that we may try to establish effective methods of treatment and preventative measures to delay, or even arrest, disease progression, thereby reducing visual morbidity. AIM To determine the lens thickness using A-scan biometry and its significance in various stages of angle closure disease. MATERIALS AND METHODS Patients attending outpatient department at Minto Ophthalmic Hospital between October 2013 to May 2015 were screened for angle closure disease and subsequently evaluated at glaucoma department. In our study, lens thickness showed a direct correlation with shallowing of the anterior chamber by determining the LT/ ACD ratio. A decrease in anterior chamber depth is proportional to the narrowing of the angle which contributes to the progression of the angle closure disease from just apposition to occlusion enhancing the risk for optic nerve damage and visual field loss. Hence, if the lens thickness values are assessed earlier in the disease process, appropriate intervention can be planned. CONCLUSION Determination of lens changes along with anterior chamber depth and axial length morphometrically can aid in early detection of angle closure. The role of lens extraction for PACG is a subject of increased interest. Lens extraction promotes the benefits of anatomical opening of the angle, IOP reduction and improved vision. This potential intervention may be one among the armamentarium of approaches for PACG. Among the current treatment modalities

Unique interplay between electronic states and dihedral angle for the molecular rotor of diphenyldiacetylene

DEFF Research Database (Denmark)

Thulstrup, Peter Waaben; Hoffmann, Søren Vrønning; Hansen, Bjarke Knud Vilster

2011-01-01

A new analysis of the optical properties of the molecular rotor 1,4-diphenyl-1,3-butadiyne (diphenyl-diacetylene, DPDA) is presented, taking account of the conformational dynamics. The absorption spectra are interpreted in terms of simultaneous contributions from planar as well as non-planar rota......A new analysis of the optical properties of the molecular rotor 1,4-diphenyl-1,3-butadiyne (diphenyl-diacetylene, DPDA) is presented, taking account of the conformational dynamics. The absorption spectra are interpreted in terms of simultaneous contributions from planar as well as non...

Optimal reconstruction angles

International Nuclear Information System (INIS)

Cook, G.O. Jr.; Knight, L.

1979-07-01

The question of optimal projection angles has recently become of interest in the field of reconstruction from projections. Here, studies are concentrated on the n x n pixel space, where literative algorithms such as ART and direct matrix techniques due to Katz are considered. The best angles are determined in a Gauss--Markov statistical sense as well as with respect to a function-theoretical error bound. The possibility of making photon intensity a function of angle is also examined. Finally, the best angles to use in an ART-like algorithm are studied. A certain set of unequally spaced angles was found to be preferred in several contexts. 15 figures, 6 tables

Tetrahedral Mesh Improvement Using Multi-face Retriangulation

DEFF Research Database (Denmark)

Misztal, Marek Krzysztof; Bærentzen, Jakob Andreas; Anton, François

2009-01-01

the algorithm is completely general with regard to quality criterion, we target improvement of the dihedral angle. The central idea in our algorithm is the introduction of a new local operation called multi-face retriangulation (MFRT) which supplements other known local operations. Like in many previous papers...

There Is No Face-to-Face Partition of R5 into Acute Simplices

Czech Academy of Sciences Publication Activity Database

Křížek, Michal

2006-01-01

Roč. 36, - (2006), s. 381-390 ISSN 0179-5376 R&D Projects: GA AV ČR(CZ) IAA1019201 Institutional research plan: CEZ:AV0Z10190503 Keywords : polytop * dihedral angle * Euler-Poincaré theorem Subject RIV: BA - General Mathematics Impact factor: 0.477, year: 2006

(2E-3-Phenylprop-2-en-1-yl thiocyanate

Directory of Open Access Journals (Sweden)

Ezzat Khan

2017-04-01

Full Text Available In the title compound, C10H9NS, the C—S—C bond angle is 99.41 (9° and the dihedral angle between the trans-alkene fragment and the benzene ring is 16.49 (19°. In the crystal, inversion dimers linked by pairs of extremely weak C—H...N interactions occur, as does a short S...N contact [3.2258 (19 Å].

2-Dichloromethyl-N-ethyl-5-(1-phenylsilolan-1-ylcyclopent-3-enecarboxamide

Directory of Open Access Journals (Sweden)

Han Xiao

2013-10-01

Full Text Available In the title compound, C19H25Cl2NOSi, the NH group and the carbonyl O atom of the amide fragment are involved in an intermolecular N—H...O hydrogen bond forming chains of molecules. The plane of the benzene ring forms a dihedral angle of 50.5 (2° with respect to the silolane ring and an angle of 49.74 (2° with the cyclopentyl moiety.

(2E-3-[4-(Dimethylaminophenyl]-1-(4-fluorophenylprop-2-en-1-one

Directory of Open Access Journals (Sweden)

Jerry P. Jasinski

2011-02-01

Full Text Available The mean planes of the two benzene rings in the title compound, C17H16FNO, are twisted slightly, making a dihedral angle of 7.8 (1°. The prop-2-en-1-one group is also twisted slightly with a C—C—C—O torsion angle of −11.6 (3°. In the crystal, weak intermolecular C—H...O interactions link pairs of molecules, forming centrosymmetric dimers.

{2-[(4-Nitrobenzylideneamino]-4,5,6,7-tetrahydro-1-benzothiophen-3-yl}(phenylmethanone

Directory of Open Access Journals (Sweden)

Manpreet Kaur

2014-06-01

Full Text Available In the title compound, C22H18N2O3S, disorder is found in the benzoyl group (A and B, as well as for four C atoms of the cyclohexene ring. Two orientations were modeled in a 0.583 (5:0.417 (5 ratio. The cyclohexene ring is in a distorted chair conformation. The dihedral angles between the mean plane of the thiophene ring and the 4-nitrobenzene and phenyl rings are 30.9 (8 and 64.8 (3 (A and 62.4 (7° (B. The mean planes of the 4-nitrobenzene and the phenyl rings are almost perpendicular to each other, with dihedral angles of 85.4 (1 (A and 83.9 (8° (B. An extensive array of weak C—H...O interactions consolidate molecules into a three-dimensional architecture, forming chains along [001] and [010] and layers parallel to (011.

Ensemble of Transition State Structures for the Cis-Trans Isomerization of N-Methylacetamide

Energy Technology Data Exchange (ETDEWEB)

Mantz, Yves A. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Branduardi, Davide [Italian Inst. of Technology, Genoa (Italy); Bussi, Giovanni [Univ. of Modena and Reggio Emilia and INFM-CNR (Italy); Parrinello, Michele [ETH Zurich, Lugano (Switzerland). Dept. of Chemistry and Applied Biosciences

2009-09-17

The cis-trans isomerization of N-methylacetamide (NMA), a model peptidic fragment, is studied theoretically in vacuo and in explicit water solvent at 300 K using the metadynamics technique. The computed cis-trans free energy difference is very similar for NMA(g) and NMA(aq), in agreement with experimental measurements of population ratios and theoretical studies at 0 K. By exploiting the flexibility in the definition of a pair of recently introduced collective variables (Branduardi, D.; Gervasio, F. L.; Parrinello, M. J. Chem. Phys. 2007, 126, 054103), an ensemble of transition state structures is generated at finite temperature for both NMA(g) and NMA(aq), as verified by computing committor distribution functions. Ensemble members of NMA(g) are shown to have correlated values of the backbone dihedral angle and a second dihedral angle involving the amide hydrogen atom. The dynamical character of these structures is preserved in the presence of solvent, whose influence on the committor functions can be modeled using effective friction/noise terms.

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazo­cine-6,12-dione acetic acid hemisolvate

Science.gov (United States)

Abbassi, Najat; Bassou, Oulemda; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-01-01

The mol­ecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11)°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12)°. In the crystal, the mol­ecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent mol­ecule by non-classical O—H⋯O and C—H⋯O hydrogen bonds. Two half-occupied acetic acid solvent mol­ecules are disordered at the same site and linked by a center of symmetry. PMID:23634138

5,11-Ditosyl-5H,11H-dibenzo[b,f][1,5]diazo-cine-6,12-dione acetic acid hemisolvate.

Science.gov (United States)

Abbassi, Najat; Bassou, Oulemda; Rakib, El Mostapha; Saadi, Mohamed; El Ammari, Lahcen

2013-04-01

The mol-ecular structure of the title compound, C28H22N2O6S2·0.5CH3COOH, is built up from three fused rings, two six and one eight membered. The eight-membered ring shows a boat conformation and the dihedral angle between the two benzene groups attached thereto is 66.43 (11)°, resulting in a V-shaped geometry. Two tosyl substituents are bound to the N atoms. The planes through the tolyl rings are roughly perpendicular, as indicated by the dihedral angle of 82.44 (12)°. In the crystal, the mol-ecule and its inversion-related symmetry-equivalent are linked to the acetic acid solvent mol-ecule by non-classical O-H⋯O and C-H⋯O hydrogen bonds. Two half-occupied acetic acid solvent mol-ecules are disordered at the same site and linked by a center of symmetry.

Synthesis, characterization and crystal structure of 6-Chloro-4,4‧-dimethyl-2,2‧-bipyridine and 4,4‧-Dimethyl 2,2‧-bipyridine N-Oxide

Science.gov (United States)

Conterosito, Eleonora; Magistris, Claudio; Barolo, Claudia; Croce, Gianluca; Milanesio, Marco

2016-03-01

The synthesis, the NMR characterization and the crystal structure of 6-Chloro 4,4‧-dimethyl 2,2‧-bipyridine and of the reaction intermediate 4,4‧-Dimethyl 2,2‧-bipyridine N-Oxide are here reported. The target compound crystallizes in the orthorhombic system while the intermediate is monoclinic. In both structures, the molecules are linked by weak interactions. The structure of the reaction intermediate N-oxide is characterized by a dihedral angle between the two phenyl rings of 161.77° while the other is almost planar with a dihedral angle of 179.15°. The crystal packing was investigated, also with the aid of Hirshfeld surface analysis. In the N-oxide reaction intermediate the packing is governed by CH-O interactions, while in the product the packing is simply driven by minimizing the voids and thus maximizing the density, with a prevalence of H•••H and C•••H contacts, as indicated by fingerprint decomposition analysis.

Bis(2-amino-1,3-benzothiazole-κN3dichloridozinc(II ethanol hemisolvate

Directory of Open Access Journals (Sweden)

Young-Inn Kim

2012-02-01

Full Text Available In the title compound, [ZnCl2(C7H6N2S2]·0.5CH3CH2OH, the ZnII atom is coordinated by two N atoms of two 2-aminobenzothiazole ligands and two Cl atoms within a distorted tetrahedral geometry. The dihedral angle between the N/Zn/N and Cl/Zn/Cl planes is 86.22 (7°. The benzothiazole molecules are almost perpendicular to each other, forming a dihedral angle of 80.20 (8°. The molecular structure is stabilized by intramolecular N—H...Cl hydrogen bonds. In the crystal, intermolecular N—H...Cl hydrogen bonds link the molecules into a three-dimensional network. The SQUEEZE procedure in PLATON [Spek (2009. Acta Cryst. D65, 148–155] was used to model a disordered ethanol solvent molecule; the calculated unit-cell data allow for the presence of half of this molecule in the asymmetric unit.

(4-Chloroacetanilido-κ2N,Obis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III

Directory of Open Access Journals (Sweden)

Lijun Sun

2013-02-01

Full Text Available In the neutral mononuclear iridium(III title compound, [Ir(C8H7ClNO(C11H8N2], the IrIII atom adopts an octahedral geometry, and is coordinated by two 2-phenylpyridyl ligands and one anionic 4-chloroacetanilide ligand. The 2-phenylpyridyl ligands are arranged in a cis-C,C′ and cis-N,N′ fashion. Each 2-phenylpyridyl ligand forms a five-membered ring with the IrIII atom. The 2-phenylpyridyl planes are perpendicular to each other [dihedral angle = 89.9 (1°]. The Ir—C and Ir—N bond lengths are comparable to those reported for related iridium(III 2-phenylpyridyl complexes. The remaining two coordination sites are occupied by the amidate N and O atoms, which form a four-membered ring with the iridium atom (Ir—N—C—O. The amidate plane is nearly perpendicular to both 2-phenylpyridyl ligands [dihedral angles = 87.8 (2 and 88.3 (2°].

Crystal structures of Schiff base derivatives of 1-(3,4,5-trimethoxybenzylidene)thiosemicarbazide and (E)-N′-(3-nitrobenzylidene)isonicotinohydrazide

Energy Technology Data Exchange (ETDEWEB)

Dileep, C. S., E-mail: dileep.mmp.phy@gmail.com; Sridhar, M. A. [Department of Studies in Physics, Manasagangotri, University of Mysore, Mysore-570006 (India); Mallesh, L. [Department of Chemistry, JSS College of Arts, Commerce and Science, Ooty Road, Mysore-570025 (India)

2014-04-24

The crystal structures of 1-(3,4,5-trimethoxybenzylidene)thiosemicarbazide (1) and N′-(3-nitrobenzylidene) isonicotinohydrazide (2) have been determined by single-crystal X-ray diffraction. In compound 1, the position of C8, O1, O2, O3 atoms are in a distorted trigonal planar geometry. The mean plane of 3,4,5-trimethoxybenzylidene ring forms a dihedral angle of 5.39(14)° with the mean plane of thiosemicarbazide group. In the structure, the molecular packing is stabilized by intermolecular N–H with diaresisN, O–H with diaresisS and intramolecular C–H with diaresisO hydrogen bonds. In compound 2, the position of C8 atom and N1 atom are in a distorted trigonal planar geometry. The mean plane of phenyl ring forms a dihedral angle of 8.09° with that of the pyridine ring. In the structure, the molecular packing is stabilized by intermolecular N–H with diaresisN and intramolecular C–H with diaresisO hydrogen bonds.

2,3-Dibromo-3-(2-bromophenyl-1-(3-phenylsydnon-4-ylpropan-1-one

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Balakrishna Kalluraya

2010-12-01

Full Text Available In the title compound [systematic name: 2,3-dibromo-3-(2-bromophenyl-1-(5-oxido-3-phenyl-1,2,3-oxadiazol-3-ium-4-ylpropan-1-one], C17H11Br3N2O3, the oxadiazole ring is essentially planar, with a maximum deviation of 0.003 (1 Å. The –CHBr–CHBr– chain and bromophenyl ring are disordered over two sets of sites with a refined occupany ratio of 0.756 (5:0.244 (5. The central oxadiazole ring makes dihedral angles of 54.07 (11 and 13.76 (18° with the attached phenyl and the major component of the bromo-substituted benzene rings, respectively. The dihedral angle between the major and minor components of the bromophenyl rings is 13.4 (5°. In the crystal structure, molecules are connected by C—H...O hydrogen bonds, forming [010] ribbons.

2-Phenyl-7-(4-pyridylmethylamino-1,2,4-triazolo[1,5-a][1,3,5]triazin-5(4H-oneFused heterocyclic systems with s-triazine ring. Part 17. For part 16, see Dolzhenko et al. (2011.

Directory of Open Access Journals (Sweden)

Lip Lin Koh

2011-01-01

Full Text Available In the title compound, C16H13N7O, the 1,2,4-triazolo[1,5-a][1,3,5]triazine heterocyclic system is essentially planar (r.m.s. deviation = 0.0375 Å. The attached benzene ring lies almost in the mean plane of 1,2,4-triazolo[1,5-a][1,3,5]triazine [dihedral angle = 1.36 (23°], while the pyridine ring is turned out of this plane by the aminomethyl bridge [dihedral angle = 69.22 (9°]. The amino group H atom is involved in intramolecular hydrogen bonding with a triazole N atom. In the crystal, molecules are connected via C(=ONH...N hydrogen bonds into C(11 chains parallel to [100]. The amino group H atom acts as a hydrogen-bond donor, forming an NH...O=C hydrogen bond with the carbonyl O atom, which links the molecules into C(6 chains running along [011] and [01overline{1}].

The mechanism of the emergence of distinct overstretched DNA states

Energy Technology Data Exchange (ETDEWEB)

Zhu, You-Liang; Sun, Zhao-Yan, E-mail: zysun@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Lu, Zhong-Yuan [State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China)

2016-01-14

Although multiple overstretched DNA states were identified in experiments, the mechanism of the emergence of distinct states is still unclear. Molecular dynamics simulation is an ideal tool to clarify the mechanism, but the force loading rates in stretching achieved by conventional all-atom DNA models are much faster, which essentially affect overstretching states. We employed a modified coarse-grained DNA model with an unprecedented low loading rate in simulations to study the overstretching transitions of end-opened double-stranded DNA. We observed two-strand peeling off for DNA with low stability and the S-DNA with high stability under tension. By introducing a melting-forbidden model which prevents base-pair breaking, we still observed the overstretching transition induced by the formation of S-DNA due to the change of dihedral angle. Hence, we confirmed that the competition between the two strain-softening manners, i.e., base-pair breaking and dihedral angle variation, results in the emergence of distinct overstretched DNA states.

Incident angle dependence of reactions between graphene and hydrogen atom by molecular dynamics simulation

International Nuclear Information System (INIS)

Saito, Seiki; Nakamura, Hiroaki; Ito, Atsushi

2010-01-01

Incident angle dependence of reactions between graphene and hydrogen atoms are obtained qualitatively by classical molecular dynamics simulation under the NVE condition with modified Brenner reactive empirical bond order (REBO) potential. Chemical reaction depends on two parameters, i.e., polar angle θ and azimuthal angle φ of the incident hydrogen. From the simulation results, it is found that the reaction rates strongly depend on polar angle θ. Reflection rate becomes larger with increasing θ, and the θ dependence of adsorption rate is also found. The θ dependence is caused by three dimensional structure of the small potential barrier which covers adsorption sites. φ dependence of penetration rate is also found for large θ. (author)

Edge detection of magnetic anomalies using analytic signal of tilt angle (ASTA)

Science.gov (United States)

Alamdar, K.; Ansari, A. H.; Ghorbani, A.

2009-04-01

Magnetic is a commonly used geophysical technique to identify and image potential subsurface targets. Interpretation of magnetic anomalies is a complex process due to the superposition of multiple magnetic sources, presence of geologic and cultural noise and acquisition and positioning error. Both the vertical and horizontal derivatives of potential field data are useful; horizontal derivative, enhance edges whereas vertical derivative narrow the width of anomaly and so locate source bodies more accurately. We can combine vertical and horizontal derivative of magnetic field to achieve analytic signal which is independent to body magnetization direction and maximum value of this lies over edges of body directly. Tilt angle filter is phased-base filter and is defined as angle between vertical derivative and total horizontal derivative. Tilt angle value differ from +90 degree to -90 degree and its zero value lies over body edge. One of disadvantage of this filter is when encountering with deep sources the detected edge is blurred. For overcome this problem many authors introduced new filters such as total horizontal derivative of tilt angle or vertical derivative of tilt angle which Because of using high-order derivative in these filters results may be too noisy. If we combine analytic signal and tilt angle, a new filter termed (ASTA) is produced which its maximum value lies directly over body edge and is easer than tilt angle to delineate body edge and no complicity of tilt angle. In this work new filter has been demonstrated on magnetic data from an area in Sar- Cheshme region in Iran. This area is located in 55 degree longitude and 32 degree latitude and is a copper potential region. The main formation in this area is Andesith and Trachyandezite. Magnetic surveying was employed to separate the boundaries of Andezite and Trachyandezite from adjacent area. In this regard a variety of filters such as analytic signal, tilt angle and ASTA filter have been applied which

Correlation of pattern reversal visual evoked potential parameters with the pattern standard deviation in primary open angle glaucoma.

Science.gov (United States)

Kothari, Ruchi; Bokariya, Pradeep; Singh, Ramji; Singh, Smita; Narang, Purvasha

2014-01-01

To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation (PSD) of Humphrey visual field could be associated with visual evoked potential (VEP) parameters of patients having primary open angle glaucoma (POAG). Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential (PRVEP) were assessed in 100 patients with POAG. The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated (full field) and displayed on VEP monitor (colour 14″) by an electronic pattern regenerator inbuilt in an evoked potential recorder (RMS EMG EP MARK II). The results of our study indicate that there is a highly significant (P<0.001) negative correlation of P100 amplitude and a statistically significant (P<0.05) positive correlation of N70 latency, P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student's t-test. Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values. Conversely, as PSD increases the magnitude of VEP excursions were found to be diminished.

Improved Beam Angle Arrangement in Intensity Modulated Proton Therapy Treatment Planning for Localized Prostate Cancer

International Nuclear Information System (INIS)

Cao, Wenhua; Lim, Gino J.; Li, Yupeng; Zhu, X. Ronald; Zhang, Xiaodong

2015-01-01

Purpose: This study investigates potential gains of an improved beam angle arrangement compared to a conventional fixed gantry setup in intensity modulated proton therapy (IMPT) treatment for localized prostate cancer patients based on a proof of principle study. Materials and Methods: Three patients with localized prostate cancer retrospectively selected from our institution were studied. For each patient, IMPT plans were designed using two, three and four beam angles, respectively, obtained from a beam angle optimization algorithm. Those plans were then compared with ones using two lateral parallel-opposed beams according to the conventional planning protocol for localized prostate cancer adopted at our institution. Results: IMPT plans with two optimized angles achieved significant improvements in rectum sparing and moderate improvements in bladder sparing against those with two lateral angles. Plans with three optimized angles further improved rectum sparing significantly over those two-angle plans, whereas four-angle plans found no advantage over three-angle plans. A possible three-beam class solution for localized prostate patients was suggested and demonstrated with preserved dosimetric benefits because individually optimized three-angle solutions were found sharing a very similar pattern. Conclusions: This study has demonstrated the potential of using an improved beam angle arrangement to better exploit the theoretical dosimetric benefits of proton therapy and provided insights of selecting quality beam angles for localized prostate cancer treatment

Rapid emission angle selection for rotating-shield brachytherapy

International Nuclear Information System (INIS)

Liu, Yunlong; Flynn, Ryan T.; Kim, Yusung; Bhatia, Sudershan K.; Sun, Wenqing; Yang Wenjun; Wu Xiaodong

2013-01-01

Purpose: The authors present a rapid emission angle selection (REAS) method that enables the efficient selection of the azimuthal shield angle for rotating shield brachytherapy (RSBT). The REAS method produces a Pareto curve from which a potential RSBT user can select a treatment plan that balances the tradeoff between delivery time and tumor dose conformity. Methods: Two cervical cancer patients were considered as test cases for the REAS method. The RSBT source considered was a Xoft Axxent TM electronic brachytherapy source, partially shielded with 0.5 mm of tungsten, which traveled inside a tandem intrauterine applicator. Three anchor RSBT plans were generated for each case using dose-volume optimization, with azimuthal shield emission angles of 90°, 180°, and 270°. The REAS method converts the anchor plans to treatment plans for all possible emission angles by combining neighboring beamlets to form beamlets for larger emission angles. Treatment plans based on exhaustive dose-volume optimization (ERVO) and exhaustive surface optimization (ERSO) were also generated for both cases. Uniform dwell-time scaling was applied to all plans such that that high-risk clinical target volume D 90 was maximized without violating the D 2cc tolerances of the rectum, bladder, and sigmoid colon. Results: By choosing three azimuthal emission angles out of 32 potential angles, the REAS method performs about 10 times faster than the ERVO method. By setting D 90 to 85–100 Gy 10 , the delivery times used by REAS generated plans are 21.0% and 19.5% less than exhaustive surface optimized plans used by the two clinical cases. By setting the delivery time budget to 5–25 and 10–30 min/fx, respectively, for two the cases, the D 90 contributions for REAS are improved by 5.8% and 5.1% compared to the ERSO plans. The ranges used in this comparison were selected in order to keep both D 90 and the delivery time within acceptable limits. Conclusions: The REAS method enables efficient RSBT

3-(4-Fluorobenzoyl-4-(4-fluorophenyl-4-hydroxy-2,6-diphenylcyclohexane-1,1-dicarbonitrile

Directory of Open Access Journals (Sweden)

B. Narayana

2014-06-01

Full Text Available In the title compound, C33H24F2N2O2, the cyclohexane ring adopts a slightly distorted chair conformation. The dihedral angle between the planes of the phenyl rings is 71.80 (9°, while the planes of the fluorophenyl and fluorobenzoyl rings are inclined to one another by 31.04 (10°. The dihedral angles between the planes of the phenyl ring adjacent to the 4-hydroxy group and those of the the fluorophenyl and fluorobenzoyl rings are 51.64 (10 and 34.31 (10°, respectively, while the corresponding angles for the phenyl ring adjacent to the 3-(4-fluorobenzoyl group are 57.51 (9 and 85.02 (10°, respectively. An intramolecular O—H...O hydrogen bond generates an S(6 ring motif. In the crystal, molecules are linked via pairs of O—H...N hydrogen bonds, forming inversion dimers. The dimers are linked via C—H...N and C—H...O hydrogen bonds, forming chains along the c-axis direction. C—H...F hydrogen bonds link the chains into sheets lying parallel to the bc plane.

Apparent Contact Angle and Contact Angle Hysteresis on Liquid Infused Surfaces

OpenAIRE

Semprebon, Ciro; McHale, Glen; Kusumaatmaja, Halim

2016-01-01

We theoretically investigate the apparent contact angle and contact angle hysteresis of a droplet placed on a liquid infused surface. We show that the apparent contact angle is not uniquely defined by material parameters, but also has a strong dependence on the relative size between the droplet and its surrounding wetting ridge formed by the infusing liquid. We derive a closed form expression for the contact angle in the limit of vanishing wetting ridge, and compute the correction for small b...

Butane-1,4-diyl bis(pyridine-4-carboxylate

Directory of Open Access Journals (Sweden)

J. Muthukumaran

2011-07-01

Full Text Available The molecule of the title compound, C16H16N2O4, lies about an inversion centre; the butane chain adopts an extended zigzag conformation. The dihedral angle between the pyridine ring and the adjacent COO group is 3.52 (s14°.

Realistic roofs over a rectilinear polygon

KAUST Repository

Ahn, Heekap; Bae, Sangwon; Knauer, Christian; Lee, Mira; Shin, Chansu; Vigneron, Antoine E.

2013-01-01

Given a simple rectilinear polygon P in the xy-plane, a roof over P is a terrain over P whose faces are supported by planes through edges of P that make a dihedral angle π/4 with the xy-plane. According to this definition, some roofs may have faces

Generating realistic roofs over a rectilinear polygon

KAUST Repository

Ahn, Heekap; Bae, Sangwon; Knauer, Christian; Lee, Mira; Shin, Chansu; Vigneron, Antoine E.

2011-01-01

Given a simple rectilinear polygon P in the xy-plane, a roof over P is a terrain over P whose faces are supported by planes through edges of P that make a dihedral angle π/4 with the xy-plane. In this paper, we introduce realistic roofs by imposing

1,5-Bis(1-phenyl-ethyl-idene)thio-carbono-hydrazide.

Science.gov (United States)

Feng, Lei; Ji, Haiwei; Wang, Renliang; Ge, Haiyan; Li, Li

2011-06-01

The title mol-ecule, C(17)H(18)N(4)S, is not planar, as indicated by the dihedral angle of 27.24 (9)° between the two benzene rings. In the crystal, inter-molecular N-H⋯S hydrogen bonds link pairs of mol-ecules into inversion dimers.

Undetected angle closure in patients with a diagnosis of open-angle glaucoma.

Science.gov (United States)

Varma, Devesh K; Simpson, Sarah M; Rai, Amandeep S; Ahmed, Iqbal Ike K

2017-08-01

The aim of this study was to identify the proportion of patients referred to a tertiary glaucoma centre with a diagnosis of open-angle glaucoma (OAG) who were found to have angle closure glaucoma. Retrospective chart review. Consecutive new patients referred for glaucoma management to a tertiary centre between July 2010 and December 2011 were reviewed. Patients whose referrals for glaucoma assessment specified angle status as "open" were included. The data collected included glaucoma specialist's angle assessment, diagnosis, and glaucoma severity. The status of those with 180 degrees or more Shaffer angle grading of 0 was classified as "closed." From 1234 glaucoma referrals, 179 cases were specified to have a diagnosis of OAG or when angles were known to be open. Of these, 16 (8.9%) were found on examination by the glaucoma specialist to have angle closure. Pseudoexfoliation was present in 4 of 16 patients (25%) in the missed angle-closure glaucoma (ACG) group and 22 of 108 patients (13.5%) in the remaining OAG group. There was no difference found in demographic or ocular biometric parameters between those with confirmed OAG versus those with missed ACG. Almost 1 in 11 patients referred by ophthalmologists to a tertiary glaucoma centre with a diagnosis of OAG were in fact found to have angle closure. Given the different treatment approaches for ACG versus OAG, this study suggests a need to strengthen angle evaluations. Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

Improved estimation of leaf area index and leaf chlorophyll content of a potato crop using multi-angle spectral data – potential of unmanned aerial vehicle imagery

NARCIS (Netherlands)

Roosjen, Peter P.J.; Brede, Benjamin; Suomalainen, Juha M.; Bartholomeus, Harm M.; Kooistra, Lammert; Clevers, Jan G.P.W.

2018-01-01

In addition to single-angle reflectance data, multi-angular observations can be used as an additional information source for the retrieval of properties of an observed target surface. In this paper, we studied the potential of multi-angular reflectance data for the improvement of leaf area index

Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

Science.gov (United States)

Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

2014-09-28

We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

Directory of Open Access Journals (Sweden)

Harsha L Rao

2012-01-01

Full Text Available Background: Blotchy pigments in the anterior chamber (AC angle are considered diagnostic of primary angle closure (PAC. But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects, above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3 and in open angles was 4.7% (95% CI, 3.2-6.3. Blotchy pigments were more frequently seen in inferior (16% and superior quadrants (15% of occludable angles, and inferior quadrant of open angles (4%. Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1. Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments.

Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

Science.gov (United States)

Rao, Harsha L; Mungale, Sachin C; Kumbar, Tukaram; Parikh, Rajul S; Garudadri, Chandra S

2012-01-01

Background: Blotchy pigments in the anterior chamber (AC) angle are considered diagnostic of primary angle closure (PAC). But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON) in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects), above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3) and in open angles was 4.7% (95% CI, 3.2-6.3). Blotchy pigments were more frequently seen in inferior (16%) and superior quadrants (15%) of occludable angles, and inferior quadrant of open angles (4%). Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1). Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments. PMID:23202393

Multi-angled Façade System for Office Building Renovation

DEFF Research Database (Denmark)

Hannoudi, Loay Akram; Christensen, Jørgen Erik; Lauring, Michael

renovating office buildings. The architectural potential is presented with the help of AutoCAD software. The energy efficiency and indoor climate are investigated and evaluated by using correlational research and simulation research methods with the software IDA ICE. From a functional perspective, the multi......-angled façade increases the area of the office room and provides more space. There are many potential aesthetic benefits provided by multi-angled façades such as improved optical and visual quality from inside the office room and the possibility for daylight penetration and a view to outside from one part...... compared to a renovated flat façade varies between 4.9 and 6.5 kWh/(m2.year), depending on the orientation of the façade. The increase in the office room area, when renovated with a multi-angled façade, is by 19%, while the increase of the yearly primary energy consumption (not area weighted), is by 4...

Uniform and selective deuteration in two-dimensional NMR of proteins

International Nuclear Information System (INIS)

LeMaster, D.M.

1990-01-01

This paper reports on the practicality of isotopic labeling, particularly deuteration, that has received considerable impetus from advances in molecular biology, which have allowed ready production of NMR quantities of labeled proteins. Protein expression in Escherichia coli allows use of the considerable metabolic genetics known for the organism in shaping the biosynthetic process to meet the labeling demands of the NMR experiments. In addition to deuteration's common use in spectral assignment problems, it also offers considerable potential for enhancing the quality of the nuclear Overhauser effect (NOE) distance and dihedral angle constraints used for solution structural analysis of proteins. Recent reviews emphasize the sample preparation and spectral benefits of protein deuteration

Crystal structure of (E-4,4,4-trifluoro-3-phenylbut-2-enoic acid

Directory of Open Access Journals (Sweden)

Alexey Barkov

2015-12-01

Full Text Available In the title compound, C10H7F3O2, the dihedral angle between the benzene ring and the ethylene plane is 76.34 (11°. In the crystal, O—H...O hydrogen bonds link the molecules into C(4 chains propagating in [010].

Computational Study of Environmental Effects on Torsional Free Energy Surface of N-Acetyl-N'-methyl-L-alanylamide Dipeptide

Science.gov (United States)

Carlotto, Silvia; Zerbetto, Mirco

2014-01-01

We propose an articulated computational experiment in which both quantum mechanics (QM) and molecular mechanics (MM) methods are employed to investigate environment effects on the free energy surface for the backbone dihedral angles rotation of the small dipeptide N-Acetyl-N'-methyl-L-alanylamide. This computation exercise is appropriate for an…

Thermochemical Properties and Relative Stability of Polychlorinated Biphenyls.

Czech Academy of Sciences Publication Activity Database

Bureš, M.; Pekárek, Vladimír; Ocelka, T.

2008-01-01

Roč. 25, 2 (2008) , s. 148-155 ISSN 1382-6689 R&D Projects: GA ČR(CZ) GA104/07/1212 Institutional research plan: CEZ:AV0Z40720504 Keywords : pcb * dihedral angle * enthalpy of formation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.051, year: 2008

Correlation of pattern reversal visual evoked potential parameters with the pattern standard deviation in primary open angle glaucoma

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Ruchi Kothari

2014-04-01

Full Text Available AIM:To evaluate whether glaucomatous visual field defect particularly the pattern standard deviation (PSD of Humphrey visual field could be associated with visual evoked potential (VEP parameters of patients having primary open angle glaucoma (POAG.METHODS:Visual field by Humphrey perimetry and simultaneous recordings of pattern reversal visual evoked potential (PRVEP were assessed in 100 patients with POAG. The stimulus configuration for VEP recordings consisted of the transient pattern reversal method in which a black and white checker board pattern was generated (full field and displayed on VEP monitor (colour 14” by an electronic pattern regenerator inbuilt in an evoked potential recorder (RMS EMG EP MARK II.RESULTS:The results of our study indicate that there is a highly significant (P<0.001 negative correlation of P100 amplitude and a statistically significant (P<0.05 positive correlation of N70 latency, P100 latency and N155 latency with the PSD of Humphrey visual field in the subjects of POAG in various age groups as evaluated by Student’s t-test.CONCLUSION:Prolongation of VEP latencies were mirrored by a corresponding increase of PSD values. Conversely, as PSD increases the magnitude of VEP excursions were found to be diminished.

Azimuthal angle dependence of Coulomb and nuclear interactions between two deformed nuclei

International Nuclear Information System (INIS)

Ismail, M.; Ellithi, A. Y.; Botros, M. M.; Mellik, A. E.

2007-01-01

The azimuthal angle (φ) variation of the Coulomb and nuclear heavy ion (HI) potentials is studied in the framework of the double folding model, which is derived from realistic nuclear density distributions and a nucleon-nucleon (NN) interaction. The present calculation shows that the variation of HI potentials with the azimuthal angle depends strongly on the range of the NN forces. For the long-range Coulomb force, the maximum variation with φ is about 0.9%, and for HI potential derived from zero-range NN interaction the φ-variation can reach up to 90.0%. Our calculations are compared with the recent φ-dependence of the HI potential derived from proximity method. The present realistic φ-dependence calculations of the HI potential is completely different from the results of the proximity calculations

SWIMS: a small-angle multiple scattering computer code

International Nuclear Information System (INIS)

Sayer, R.O.

1976-07-01

SWIMS (Sigmund and WInterbon Multiple Scattering) is a computer code for calculation of the angular dispersion of ion beams that undergo small-angle, incoherent multiple scattering by gaseous or solid media. The code uses the tabulated angular distributions of Sigmund and Winterbon for a Thomas-Fermi screened Coulomb potential. The fraction of the incident beam scattered into a cone defined by the polar angle α is computed as a function of α for reduced thicknesses over the range 0.01 less than or equal to tau less than or equal to 10.0. 1 figure, 2 tables

Pitch angle scattering of an energetic magnetized particle by a circularly polarized electromagnetic wave

International Nuclear Information System (INIS)

Bellan, P. M.

2013-01-01

The interaction between a circularly polarized wave and an energetic gyrating particle is described using a relativistic pseudo-potential that is a function of the frequency mismatch. Analysis of the pseudo-potential provides a means for interpreting numerical results. The pseudo-potential profile depends on the initial mismatch, the normalized wave amplitude, and the initial angle between the wave magnetic field and the particle perpendicular velocity. For zero initial mismatch, the pseudo-potential consists of only one valley, but for finite mismatch, there can be two valleys separated by a hill. A large pitch angle scattering of the energetic electron can occur in the two-valley situation but fast scattering can also occur in a single valley. Examples relevant to magnetospheric whistler waves show that the energetic electron pitch angle can be deflected 5°towards the loss cone when transiting a 10 ms long coherent wave packet having realistic parameters.

Crystal structure of (E-1-(4′-methoxy-[1,1′-biphenyl]-4-yl-3-(3-nitrophenylprop-2-en-1-one

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T. Vidhyasagar

2015-01-01

Full Text Available The title compound, C22H17NO4, crystallizes with two independent molecules (A and B in the asymmetric unit. Each molecule exists as an E isomer with C—C=C—C torsion angles of −175.69 (17 and −178.41 (17° in A and B, respectively. In molecule A, the planes of the terminal benzene rings are twisted by an angle of 26.67 (10°, while the biphenyl unit is non-planar, the dihedral angle between the rings being 30.81 (10°. The dihedral angle between the nitrophenyl ring and the inner phenyl ring is 6.50 (9°. The corresponding values in molecule B are 60.61 (9, 31.07 (8 and 31.05 (9°. In the crystal, molecules are arranged in a head-to-head manner, with the 3-nitrophenyl groups nearly parallel to one another. The A and B molecules are linked to one another via C—H...O hydrogen bonds, forming chains lying parallel to (-320 and enclosing R22(10 and R22(12 ring motifs. The methoxy group in both molecules is positionally disordered with a refined occupancy ratio of 0.979 (4:0.021 (4 for molecule A and 0.55 (4:0.45 (4 for molecule B.

Contact Angle Goniometer

Data.gov (United States)

Federal Laboratory Consortium — Description:The FTA32 goniometer provides video-based contact angle and surface tension measurement. Contact angles are measured by fitting a mathematical expression...

Ethyl 1-cyclopropyl-6,7-difluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylate

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De-Cai Wang

2008-11-01

Full Text Available In the title compound, C16H15F2NO4, the dihedral angle between the three-membered ring and the quinoline ring system is 64.3 (3°. In the crystal structure, intermolecular C—H...O hydrogen bonds link the molecules, forming a column running along [101].

5-Ethyl-3-(2-fluorophenylsulfonyl-2-methyl-1-benzofuran

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Hong Dae Choi

2012-10-01

Full Text Available In the title compound, C17H15FO3S, the 2-fluorophenyl ring makes a dihedral angle of 89.12 (8° with the mean plane of the benzofuran fragment. In the crystal, molecules are linked by weak C—H...O and C—H...π interactions.

N′-[(E-3-Pyridylmethylidene]benzohydrazide

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Liyuan Wen

2009-11-01

Full Text Available The title compound, C13H11N3O, was prepared by the reaction of benzohydrazide and nicotinaldehyde. The dihedral angle between the planes of the two aromatic rings is 47.78 (9°. The crystal structure is stabilized by intermolecular N—H...N hydrogen-bonding interactions.

(E,E-6,6′-Dimethoxy-2,2′-[o-phenylenebis(nitrilomethylidyne]diphenol

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Yong Wang

2009-04-01

Full Text Available In the title compound, C22H20N2O4, the central benzene ring forms dihedral angles of 3.2 (2 and 61.1 (1° with the two outer substituted benzene rings. Intramolecular O—H...N hydrogen bonds are formed by both hydroxyl groups.

2,3-Bis[(3-methylbiphenyl-4-ylimino]butane

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Jingjing Chen

2014-04-01

Full Text Available The title compound, C30H28N2, is a product of the condensation reaction of 2-methyl-4-phenylaniline and butane-2,3-dione. The molecule lies on a crystallographic inversion centre. The C=N bond has an E conformation. The dihedral angle between the two benzene rings of the 4-phenyl-2-methylphenyl group is 29.19 (76°. The 1,4-diazabutadiene plane makes an angle of 70.1 (10° with the N-bonded methylphenyl ring and an angle of 81.08 (97° with the terminal phenyl group.

left-angle 100 right-angle Burgers vector in single phase γ' material verified by image simulation

International Nuclear Information System (INIS)

Link, T.; Knobloch, C.; Glatzel, U.

1998-01-01

The deformation mechanisms of Ni 3 Al, an ordered L1 2 or γ' phase, is under intense research since Westbrook showed the increase of its hardness with temperature in 1957. The super dislocations of this ordered phase normally have Burgers vectors rvec b = a left-angle 110 right-angle, disassociated in either two a/2 left-angle 110 right-angle or two rvec b = a/3 left-angle 112 right-angle, depending on deformation temperature and rate. Recent observations in [111] oriented γ' specimens suggest that additional dislocations with the shorter Burgers vector rvec b = a left-angle 100 right-angle might be active. Dislocations with rvec b = a left-angle 110 right-angle on cube glide planes have a Schmidt factor of 0.47 and on octahedral planes of 0.27. Dislocations with rvec b = a left-angle 100 right-angle have a Schmidt factor of 0.47 for {110} glide planes and 0.33 for cube glide planes. The a left-angle 100 right-angle Burgers vector is the shortest of all complete dislocations of the L1 2 structure and creates no planar fault like antiphase boundaries or stacking faults. Due to the [111] oriented stress axis, which is used in this contribution, plastic deformation by a left-angle 100 right-angle dislocations as well as cube glide planes for left-angle 110 right-angle dislocations is encouraged. These dislocations could be reaction products, but will soon after contribute to deformation

Pitch Angle Control for Variable Speed Wind Turbines

DEFF Research Database (Denmark)

Chen, Zhe; Zhang, Jianzhong; Cheng, M

2008-01-01

Pitch angle control is the most common means for adjusting the aerodynamic torque of the wind turbine when wind speed is above rated speed and various controlling variables may be chosen, such as wind speed, generator speed and generator power. As conventional pitch control usually use PI...... controller, the mathematical model of the system should be known well. A fuzzy logic pitch angle controller is developed in this paper, in which it does not need well known about the system and the mean wind speed is used to compensate the non-linear sensitivity. The fuzzy logic control strategy may have...... the potential when the system contains strong non-linearity, such as wind turbulence is strong, or the control objectives include fatigue loads. The design of the fuzzy logic controller and the comparisons with conversional pitch angle control strategies with various controlling variables are carried out...

N-(2,6-Dichlorophenyl-4-methylbenzamide

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Vinola Z. Rodrigues

2011-08-01

Full Text Available In the title compound, C14H11Cl2NO, the two aromatic rings are nearly orthogonal to each other [dihedral angle 79.7 (1°], while the central amide core –NH—C(=O– is nearly coplanar with the benzoyl ring [N—C—C—C torsion angles = −5.5 (3 and 1772. (2°]. In the crystal, intermolecular N—H...O hydrogen bonds link the molecules into C(4 chains propagating in [001].

4,4′-Di-tert-butyl-2,2′-bipyridine

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Tatiana R. Amarante

2009-08-01

Full Text Available In the title compound, C18H24N2, the molecular unit adopts a trans conformation around the central C—C bond [N—C—C—N torsion angle of 179.2 (3°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4°]. The crystal packing is driven by co-operative contacts involving weak C—H...N and C—H...π interactions, and also the need to fill effectively the available space.

N-(4-Chlorophenyl-4-nitrobenzamide

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Ghulam Waris

2012-09-01

Full Text Available The title compound, C13H9ClN2O3, is almost planar, showing a dihedral angle of 4.63 (6° between the aromatic ring planes. The nitro group also lies in the plane, the C—C—N—O torsion angle being 6.7 (2°. There is an intamolecular C—H...O hydrogen bond. The crystal structure features N—H...O(nitro hydrogen bonds that link the molecules into zigzag chains extending along [010].

Surface roughness effects on plasma near a divertor plate and local impact angle

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Wanpeng Hu

2017-08-01

Full Text Available The impact of rough surface topography on the electric potential and electric field is generally neglected due to the small scale of surface roughness compared to the width of the plasma sheath. However, the distributions of the electric potential and field on rough surfaces are expected to influence the characteristics of edge plasma and the local impact angle. The distributions of plasma sheath and local impact angle on rough surfaces are investigated by a two dimension-in-space and three dimension-in-velocity (2d3v Particle-In-Cell (PIC code. The influences of the plasma temperature andsurface morphology on the plasma sheath, local impact angle and resulting physical sputtering yield on rough surfaces are investigated.

Angle Performance on Optima XE

International Nuclear Information System (INIS)

David, Jonathan; Satoh, Shu

2011-01-01

Angle control on high energy implanters is important due to shrinking device dimensions, and sensitivity to channeling at high beam energies. On Optima XE, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through a series of narrow slits, and any angle adjustment is made by steering the beam with the corrector magnet. In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightly tilting the wafer platen during implant.Using a sensitive channeling condition, we were able to quantify the angle repeatability of Optima XE. By quantifying the sheet resistance sensitivity to both horizontal and vertical angle variation, the total angle variation was calculated as 0.04 deg. (1σ). Implants were run over a five week period, with all of the wafers selected from a single boule, in order to control for any crystal cut variation.

Radical cation spectroscopy of substituted alkyl phenyl ketones via tunnel ionization

Energy Technology Data Exchange (ETDEWEB)

Bohinski, Timothy; Moore Tibbetts, Katharine [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Munkerup, Kristin [Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø (Denmark); Tarazkar, Maryam [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Romanov, Dmitri A. [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Physics, Temple University, Philadelphia, PA 19122 (United States); Matsika, Spiridoula [Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States); Levis, Robert J., E-mail: rjlevis@temple.edu [Center for Advanced Photonics Research, Temple University, Philadelphia, PA 19122 (United States); Department of Chemistry, Temple University, Philadelphia, PA 19122 (United States)

2014-10-17

Highlights: • Infrared strong field spectroscopy on (o, m, p)-methylacetophenone was performed. • Electronic resonance in the radical cations at 1370 nm produces benzoyl fragment. • Magnitude of resonance feature increases from ortho to meta to para isomer. • Hydrogen interactions and moment of inertia account for the trend across isomers. - Abstract: Mass spectra are measured for 2′-, 3′- and 4′-(ortho, meta and para) methyl substituted alkyl phenyl ketones excited at wavelengths ranging from 1200 to 1500 nm in the strong field regime. The selective loss of a methyl group from the acetyl group of the parent molecular ion upon excitation at ∼1370 nm is attributed to an electronic resonance between ground D{sub 0} and excited D{sub 2} state of the radical cation. Depletion of the parent molecular ion is enhanced as the methyl substituent is moved from the 2′ to 3′ to 4′ position on the phenyl ring with respect to the acetyl group. The phenyl-acetyl dihedral angle is the relevant coordinate enabling excitation to the dissociative D{sub 2} state. Calculations on the radical cation of 2′-methylacetophenone show two stable geometries with dihedral angles of 7 degrees and 63 degrees between the phenyl and acetyl groups. The barrier to rotation for the 2′ isomer limits population transfer to the D{sub 2} state. In contrast, calculations on the radical cations of 3′- and 4′-methylacetophenone reveal no rotational barrier to prevent population transfer to the excited state, which is consistent with the enhanced dissociation yield in comparison with the 2′ substitution. The enhanced dissociation of the 4′ isomer as compared to the 3′ isomer is attributed to its lower moment of inertia about the dihedral angle.

Anomalous incident-angle and elliptical-polarization rotation of an elastically refracted P-wave

Science.gov (United States)

Fa, Lin; Fa, Yuxiao; Zhang, Yandong; Ding, Pengfei; Gong, Jiamin; Li, Guohui; Li, Lijun; Tang, Shaojie; Zhao, Meishan

2015-08-01

We report a newly discovered anomalous incident-angle of an elastically refracted P-wave, arising from a P-wave impinging on an interface between two VTI media with strong anisotropy. This anomalous incident-angle is found to be located in the post-critical incident-angle region corresponding to a refracted P-wave. Invoking Snell’s law for a refracted P-wave provides two distinctive solutions before and after the anomalous incident-angle. For an inhomogeneously refracted and elliptically polarized P-wave at the anomalous incident-angle, its rotational direction experiences an acute variation, from left-hand elliptical to right-hand elliptical polarization. The new findings provide us an enhanced understanding of acoustical-wave scattering and lead potentially to widespread and novel applications.

{1-[(3,5-Dimethyl-4H-1,2,4-triazol-4-ylimino]ethyl}ferrocene

Directory of Open Access Journals (Sweden)

Mao-Ping Song

2008-10-01

Full Text Available In the title compound, [Fe(C5H5(C11H13N4], the triazolyl and Cp ring form a dihedral angle of 76.6 (3°. In the crystal structure, there are both intra- and intermolecular C—H...π interactions, forming a one-dimensional chain structure along [010].

3,4-Dimethoxy-N-(4-nitrobenzylideneaniline

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Aliasghar Jarrahpour

2008-11-01

Full Text Available In the title molecule, C15H14N2O4, the dihedral angle between the two benzene rings is 29.52 (8°. The nitro and two methoxy substituents are almost coplanar with their respective benzene rings. The crystal structure is stabilized by intermolecular C—H...O interactions.

1,4-Bis(4-chlorophenylbutane-1,4-dione

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Huisheng Li

2008-12-01

Full Text Available The molecule of title compound, C16H12Cl2O2, is centrosymmetric. Thus, the asymmetric unit comprises two half-molecules. The two benzene rings are coplanar in each independent molecule (dihedral angles = 0°. The crystal packing exhibits intermolecular C—H...O hydrogen bonds and C—H...π interactions.

2-Isopropyl-5-methylcyclohexyl quinoline-2-carboxylate

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E. Fazal

2014-01-01

Full Text Available In the title compound, C20H25NO2, the cyclohexyl ring adopts a slightly disordered chair conformation. The dihedral angle between the mean planes of the quinoline ring and the carboxylate group is 22.2 (6°. In the crystal, weak C—H...N interactions make chains along [010].

N′-[(1E-1-(4-Chlorophenylethylidene]formohydrazide

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Zahid Shafiq

2009-10-01

Full Text Available The structure of the title compound, C9H9ClN2O, consists of centrosymmetric dimers due to intermolecular N—H...O hydrogen bonding, forming R22(8 ring motifs. The dihedral angle between the p-chlorophenyl unit and the remaining heavy-atom group is 6.77 (17°.

4-[(E-(4-Fluorobenzylideneamino]benzoic acid

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Blanca M. Muñoz-Flores

2012-01-01

Full Text Available In the title compound, C14H10FNO2, the benzene rings make a dihedral angle of 57.50 (13°, and the molecule has an E configuration about the C=N bond. In the crystal, molecules are linked via pairs of O—H...O hydrogen bonds, forming inversion dimers.

4-Benzyl-6-bromo-2-phenyl-4H-imidazo[4,5-b]pyridine

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Y. Ouzidan

2010-04-01

Full Text Available The imidazopyridine fused ring in the title compound, C19H14BrN3, is almost coplanar with the phenyl ring at the 2-position of the five-membered ring [dihedral angle = 2.4 (1. The crystal structure features short Br...Br contacts [3.562 (1 Å].

1,5-Bis(1-phenyl­ethyl­idene)thio­carbono­hydrazide

Science.gov (United States)

Feng, Lei; Ji, Haiwei; Wang, Renliang; Ge, Haiyan; Li, Li

2011-01-01

The title mol­ecule, C17H18N4S, is not planar, as indicated by the dihedral angle of 27.24 (9)° between the two benzene rings. In the crystal, inter­molecular N—H⋯S hydrogen bonds link pairs of mol­ecules into inversion dimers. PMID:21754879

Exact Solutions for Internuclear Vectors and Backbone Dihedral Angles from NH Residual Dipolar Couplings in Two Media, and their Application in a Systematic Search Algorithm for Determining Protein Backbone Structure

International Nuclear Information System (INIS)

Wang Lincong; Donald, Bruce Randall

2004-01-01

We have derived a quartic equation for computing the direction of an internuclear vector from residual dipolar couplings (RDCs) measured in two aligning media, and two simple trigonometric equations for computing the backbone (φ,ψ) angles from two backbone vectors in consecutive peptide planes. These equations make it possible to compute, exactly and in constant time, the backbone (φ,ψ) angles for a residue from RDCs in two media on any single backbone vector type. Building upon these exact solutions we have designed a novel algorithm for determining a protein backbone substructure consisting of α-helices and β-sheets. Our algorithm employs a systematic search technique to refine the conformation of both α-helices and β-sheets and to determine their orientations using exclusively the angular restraints from RDCs. The algorithm computes the backbone substructure employing very sparse distance restraints between pairs of α-helices and β-sheets refined by the systematic search. The algorithm has been demonstrated on the protein human ubiquitin using only backbone NH RDCs, plus twelve hydrogen bonds and four NOE distance restraints. Further, our results show that both the global orientations and the conformations of α-helices and β-strands can be determined with high accuracy using only two RDCs per residue. The algorithm requires, as its input, backbone resonance assignments, the identification of α-helices and β-sheets as well as sparse NOE distance and hydrogen bond restraints.Abbreviations: NMR - nuclear magnetic resonance; RDC - residual dipolar coupling; NOE - nuclear Overhauser effect; SVD - singular value decomposition; DFS - depth-first search; RMSD - root mean square deviation; POF - principal order frame; PDB - protein data bank; SA - simulated annealing; MD - molecular dynamics

Large area optical mapping of surface contact angle.

Science.gov (United States)

Dutra, Guilherme; Canning, John; Padden, Whayne; Martelli, Cicero; Dligatch, Svetlana

2017-09-04

Top-down contact angle measurements have been validated and confirmed to be as good if not more reliable than side-based measurements. A range of samples, including industrially relevant materials for roofing and printing, has been compared. Using the top-down approach, mapping in both 1-D and 2-D has been demonstrated. The method was applied to study the change in contact angle as a function of change in silver (Ag) nanoparticle size controlled by thermal evaporation. Large area mapping reveals good uniformity for commercial Aspen paper coated with black laser printer ink. A demonstration of the forensic and chemical analysis potential in 2-D is shown by uncovering the hidden CsF initials made with mineral oil on the coated Aspen paper. The method promises to revolutionize nanoscale characterization and industrial monitoring as well as chemical analyses by allowing rapid contact angle measurements over large areas or large numbers of samples in ways and times that have not been possible before.

On the Angular Dependence of the Vicinal Fluorine-Fluorine Coupling Constant in 1,2-Difluoroethane:  Deviation from a Karplus-like Shape.

Science.gov (United States)

Provasi, Patricio F; Sauer, Stephan P A

2006-07-01

The angular dependence of the vicinal fluorine-fluorine coupling constant, (3)JFF, for 1,2-difluoroethane has been investigated with several polarization propagator methods. (3)JFF and its four Ramsey contributions were calculated using the random phase approximation (RPA), its multiconfigurational generalization, and both second-order polarization propagator approximations (SOPPA and SOPPA(CCSD)), using locally dense basis sets. The geometries were optimized for each dihedral angle at the level of density functional theory using the B3LYP functional and fourth-order Møller-Plesset perturbation theory. The resulting coupling constant curves were fitted to a cosine series with 8 coefficients. Our results are compared with those obtained previously and values estimated from experiment. It is found that the inclusion of electron correlation in the calculation of (3)JFF reduces the absolute values. This is mainly due to changes in the FC contribution, which for dihedral angles around the trans conformation even changes its sign. This sign change is responsible for the breakdown of the Karplus-like curve.

Crystal structure of 2-pentyloxybenzamide

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Bernhard Bugenhagen

2014-10-01

Full Text Available In the title molecule, C12H17NO2, the amide NH2 group is oriented toward the pentyloxy substituent and an intramolecular N—H...O hydrogen bond is formed with the pentyloxy O atom. The benzene ring forms dihedral angles of 2.93 (2 and 5.60 (2° with the amide group and the pentyloxy group mean planes, respectively. In the crystal, molecules are linked by pairs of N—H...O hydrogen bonds, forming inversion dimers with their molecular planes parallel, but at an offset of 0.45 (1 Å to each other. These dimers are ordered into two types of symmetry-related columns extended along the a axis, with the mean plane of one set of dimers in a column approximately parallel to (121 and the other in a column approximately parallel to (1-21. The two planes form a dihedral angle of 85.31 (2°, and are linked via C—H...O hydrogen bonds and C—H...π interactions, forming a three-dimensional framework structure.

Diaquabis(4-bromobenzoato-κObis(nicotinamide-κN1copper(II

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Hacali Necefoğlu

2011-07-01

Full Text Available The asymmetric unit of the title mononuclear CuII complex, [Cu(C7H4BrO22(C6H6N2O2(H2O2], contains one half-molecule, the CuII atom being located on an inversion center. The unit cell contains two nicotinamide (NA, two 4-bromobenzoate (PBB ligands and two coordinated water molecules. The four O atoms in the equatorial plane around the CuII ion form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxylate group and the adjacent benzene ring is 22.17 (16°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 82.80 (6°. In the crystal, N—H...O, O—H...O and C—H...O hydrogen bonds link the molecules into a three-dimensional network. A weak C—H...π interaction is also observed.

1,3-Dibenzyl-2-(2-chlorophenyl-4-methylimidazolidine

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Augusto Rivera

2012-12-01

Full Text Available In the title compound, C24H25ClN2, the methine, methylene and methyl C atoms of the methyl-substituted imidazolidine ring are disordered over two sets of sites with a refined occupancy ratio of 0.834 (4:0.166 (4. Each disordered ring assumes an envelope conformation with an N atom as the flap. The pendant benzyl rings are oriented equatorially with respect to the imidazolidine ring. The chlorophenyl ring is inclined to the mean plane of the four planar atoms of the major component of the imidazolidine ring by 76.27 (12°. The dihedral angles between the chlorophenyl ring and the two benzyl rings are 55.31 (9 and 57.50 (8°; the dihedral angle between these latter rings is 71.59 (9°. In the crystal, molecules are linked by C—H...Cl interactions and a number of weak C—H...π interactions, involving all three aromatic rings, forming a three-dimensional structure.

IR and NMR spectroscopic correlation of enterobactin by DFT

Science.gov (United States)

Moreno, M.; Zacarias, A.; Porzel, A.; Velasquez, L.; Gonzalez, G.; Alegría-Arcos, M.; Gonzalez-Nilo, F.; Gross, E. K. U.

2018-06-01

Emerging and re-emerging epidemic diseases pose an ongoing threat to global health. Currently, Enterobactin and Enterobactin derivatives have gained interest, owing to their potential application in the pharmaceutical field. As it is known [J. Am. Chem. Soc (1979) 101, 20, 6097-6104], Enterobactin (H6EB) is an efficient iron carrier synthesized and secreted by many microbial species. In order to facilitate the elucidation of enterobactin and its analogues, here we propose the creation of a H6EB standard set using Density Functional Theory Infrared (IR) and NMR spectra. We used two exchange-correlation (xc) functionals (PBE including long-range corrections sbnd LC-PBEsbnd and mPW1), 2 basis sets (QZVP and 6-31G(d)) and 2 grids (fine and ultrafine) for most of the H6EB structures dependent of dihedral angles. The results show a significant difference between the Osbnd H and Nsbnd H bands, while the Cdbnd O amide and Osbnd (Cdbnd O)sbnd IR bands are often found on top of each other. The NMR DFT calculations show a strong dependence on the xc functional, basis set, and grid used for the H6EB structure. Calculated 1H and 13C NMR spectra enable the effect of the solvent to be understood in the context of the experimental measurements. The good agreement between the experimental and the calculated spectra using LC-PBE/QZVP and ultrafine grid suggest the possibility of the systems reported here to be considered as a standard set. The dependence of electrostatic potential and frontier orbitals with the catecholamide dihedral angles of H6EB is described. The matrix-assisted laser desorption/ionization time of the flight mass spectrometry (MALDI-TOF MS) of H6EB is also reported of manner to enrich the knowledge about its reactivity.

Small angle neutron scattering and small angle X-ray scattering ...

Indian Academy of Sciences (India)

Abstract. The morphology of carbon nanofoam samples comprising platinum nanopar- ticles dispersed in the matrix was characterized by small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS) techniques. Results show that the structure of pores of carbon matrix exhibits a mass (pore) fractal nature ...

Contact angle of sessile drops in Lennard-Jones systems.

Science.gov (United States)

Becker, Stefan; Urbassek, Herbert M; Horsch, Martin; Hasse, Hans

2014-11-18

Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.

Large-angle theory for pion-nucleus scattering at high energies

International Nuclear Information System (INIS)

Hoock, D.W. Jr.

1978-01-01

An approximate solution for high-energy, projectile-nucleus, multiple scattering is developed from the exact Watson series and applied to pion scattering for 12 C and 4 He. Agreement with measured differential cross sections available from the literature for the range 150 to 260 MeV pion laboratory energies is surprisingly good. The approximation method expands the propagators of the Watson series about the transverse component of the momentum transfer. Contributions of each of the first two terms to double scattering from a Gaussian potential are compared to the exact solution. The purely plane-wave propagation produces a scattering amplitude that agrees to order (k 0 a) -1 with the exact solution at the forward and backward directions at high energies. The second (off-axis) propagation term produces an amplitude that is one order smaller at forward angles and two orders smaller at 180 0 than the exact amplitude. At intermediate angles it is of the same order. The general multiple-scattering series is approximated with selection of plane-wave propagation as the fundamental process at large and small angles. This model suggests that a single nucleon accepts most of the momentum transfer for backward scattering. The resulting multiple-scattering formula agrees with the well-known high-energy eikonal theory at small angles and the backward-angle scattering formula of Chen at exactly 180 0 . A lowest-order formula that includes off-axis propagation is also derived. Predicted differential cross sections are found to be sensitive to nucleon motion and binding. For 4 He the effect of the nuclear potential on the pion kinetic energy is also examined and found to produce significant changes in the predicted cross sections

N-[3-(Benzenesulfonamidopropyl]benzenesulfonamide

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Tahir Ali Sheikh

2011-07-01

Full Text Available In the title compound, C15H18N2O4S2, the dihedral angle between the aromatic rings is 71.8 (2°. The conformation of the central N—C—C—C—N fragment is gauche–gauche [torsion angles = 72.5 (5 and 65.7 (5°]. Both N atoms adopt pyramidal geometries. In the crystal, molecules are linked by N—H...O hydrogen bonds, generating (001 sheets, and weak C—H...O interactions consolidate the packing.

Sharper angle, higher risk? The effect of cutting angle on knee mechanics in invasion sport athletes.

Science.gov (United States)

Schreurs, Mervin J; Benjaminse, Anne; Lemmink, Koen A P M

2017-10-03

Cutting is an important skill in team-sports, but unfortunately is also related to non-contact ACL injuries. The purpose was to examine knee kinetics and kinematics at different cutting angles. 13 males and 16 females performed cuts at different angles (45°, 90°, 135° and 180°) at maximum speed. 3D kinematics and kinetics were collected. To determine differences across cutting angles (45°, 90°, 135° and 180°) and sex (female, male), a 4×2 repeated measures ANOVA was conducted followed by post hoc comparisons (Bonferroni) with alpha level set at α≤0.05a priori. At all cutting angles, males showed greater knee flexion angles than females (pcutting angles with no differences in the amount of knee flexion -42.53°±8.95°, females decreased their knee flexion angle from -40.6°±7.2° when cutting at 45° to -36.81°±9.10° when cutting at 90°, 135° and 180° (pcutting towards sharper angles (pcutting angles and then stabilized compared to the 45° cutting angle (pcutting to sharper angles (pcutting angles demand different knee kinematics and kinetics. Sharper cutting angles place the knee more at risk. However, females and males handle this differently, which has implications for injury prevention. Copyright © 2017 Elsevier Ltd. All rights reserved.

4-Methoxy-3-nitrobiphenyl

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Xuqiang Chao

2012-01-01

Full Text Available In the title compound, C13H11NO3, the dihedral angle between the two benzene rings is 36.69 (2° and the nitro and methyoxy groups are oriented at 29.12 (14 and 2.14 (12° with respect to the benzene ring to which they are bonded.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 129; Issue 2 ... Rapid Communication Volume 129 Issue 2 February 2017 pp 149-156 ... The central perylene core of 1 is twisted with dihedral angles of 19.48(2)◦ and 19.50(2)◦; this twist configuration induces the axial chirality in this family of perylene bisimide ...

3-Methoxy-4-(4-nitrobenzyloxybenzaldehyde

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Xin Chen

2008-12-01

Full Text Available In the title compound, C15H13NO5, the vanillin group makes a dihedral angle of 4.95 (8° with the benzene ring of the nitrobenzene group. The packing is stabilized by weak, non-classical intermolecular C—H...O interactions which link molecules into chains running along the c axis.

2,6-Bis(2-hydroxyethyl-8b,8c-diphenylperhydro-2,3a,4a,6,7a,8a-hexaazacyclopenta[def]fluorene-4,8-dithione

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Zihua Wang

2009-06-01

Full Text Available In the title molecule, C24H28N6O2S2, the dihedral angle between the aromatic ring planes is 42.2 (1°. In the crystal structure, the hydroxy groups are involved in O—H...S hydrogen bonding, which links the molecules into corrugated layers propagating parallel to the bc plane.

Crystal structure of (E-N-phenyl-N′-[1-(thiophen-2-ylethylidene]formohydrazide

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C. S. Dileep

2014-09-01

Full Text Available In the title compound, C13H12N2OS, the planes of the thiophene and phenyl rings are nearly perpendicular to each other, making a dihedral angle of 86.42 (12°. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming a helical chain along the b-axis direction.

4,5-Bis(4-methoxyphenoxyphthalonitrile

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Tianyou Peng

2010-10-01

Full Text Available The title compound, C22H16N2O4, was obtained unintentionally as the product of an attempted synthesis of a new phthalocyanine. The dihedral angles formed by the central benzene ring with the aromatic rings of the methoxyphenoxy groups are 85.39 (5 and 64.19 (5°.

(E-N′-[4-(Dimethylaminobenzylidene]-2-(4-methylphenoxyacetohydrazide

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M. K. Usha

2014-02-01

Full Text Available In the title compound, C18H21N3O2, the dihedral angle between the benzene rings is 68.85 (11°. In the crystal, the molecules are linked by C—H...O and N—H...O hydrogen bonds, as well as weak C—H...π contacts, forming a three-dimensional supramolecular architecture.

Stereospecific assignment of the NH2 resonances from the primary amides of asparagine and glutamine side chains in isotopically labeled proteins

International Nuclear Information System (INIS)

McIntosh, Lawrence P.; Brun, Emmanuel; Kay, Lewis E.

1997-01-01

An HMQC-based pulse scheme is presented for the stereospecific assignment of asparagine and glutamine side-chain amide protons. The approach makes use of the recently developed quantitative-J correlation spectroscopy [Bax, A. et al. (1994) Methods Enzymol., 239,79-105] to distinguish the E and Z primary amide protons and, as such, eliminates the need for assignments derived from more time-consuming and potentially ambiguous NOE methods. An application of this method to a uniformly 15N,13C-labeled cellulose-binding domain is presented. When used in combination with a NOESY-HSQC experiment, the predominant χ2 dihedral angles of two asparagine side chains in this protein can also be defined

Computational Study of Geometry, Solvation Free Energy, Dipole Moment, Polarizability, Hyperpolarizability and Molecular Properties of 2-Methylimidazole

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Mohammad Firoz Khan

2016-12-01

Full Text Available Ab initio calculations were carried out to study the geometry, solvation free energy, dipole moment, molecular electrostatic potential (MESP, Mulliken and Natural charge distribution, polarizability, hyperpolarizability, Natural Bond Orbital (NBO energetic and different molecular properties like global reactivity descriptors (chemical hardness, softness, chemical potential, electronegativity, electrophilicity index of 2-methylimidazole. B3LYP/6-31G(d,p level of theory was used to optimize the structure both in the gas phase and in solution. The solvation free energy, dipole moment and molecular properties were calculated by applying the Solvation Model on Density (SMD in four solvent systems, namely water, dimethylsulfoxide (DMSO, n-octanol and chloroform. The computed bond distances, bond angles and dihedral angles of 2-methylimidazole agreed reasonably well with the experimental data except for C(2-N(1, C(4-C(5 and N(1-H(7 bond lengths and N(1-C(5-C(4 bond angle. The solvation free energy, dipole moment, polarizability, first order hyperpolarizability, chemical potential, electronegativity and electrophilicity index of 2-methylimidazole increased on going from non-polar to polar solvents. Chemical hardness also increased with increasing polarity of the solvent and the opposite relation was found in the case of softness. These results provide better understanding of the stability and reactivity of 2-methylimidazole in different solvent systems.

CONTACT ANGLE OF YUCCA MOUNTAIN WELDED TUFF WITH WATER AND BRINES

International Nuclear Information System (INIS)

H. Kalia

2006-01-01

A number of tests were performed to acquire contact angles between Yucca Mountain welded tuff from Topopah Springs Lower Lithophysal geologic unit and various brine solutions. The tests were performed on core disks received from Sample Management Facility (SMF), oven dried to a constant weight and the core disks vacuum saturated in: distilled water, J-13 water, calcium chloride brine and sodium chloride brine to constant weight. The contact angles were acquired from eight points on the surface of the core disks, four on rough surface, and four on polished surface. The contact angle was measured by placing a droplet of the test fluid, distilled water, J-13 water, calcium chloride brine and sodium chloride brine on the core disks. The objective of this test was to acquire contact angles as a potential input to estimating capillary forces in accumulated dust on the waste packages and drip shields slated for the proposed High-Level Radioactive Waste Repository at Yucca Mountain, Nevada. It was noted that once the droplet contacts the test surface, it continues to spread hence the contact angle continues to decrease with elapsed time. The maximum observed angle was at time 0 or when the drop contacted the rock surface. The measured contact angle, in all cases has significant scatter. In general, the time zero contact angles for core disks saturated in sodium chloride brine were smaller than those saturated in calcium chloride brine, distilled water, and J-13 water. The contact angles for samples saturated in distilled water, J-13 water and calcium chloride brine at time zero were similar. There was slight difference between the observed contact angles for smooth and rough surface of the test samples. The contact angles for smooth surfaces were smaller than for the rough surfaces

Dynamics and control of robotic aircraft with articulated wings

Science.gov (United States)

Paranjape, Aditya Avinash

There is a considerable interest in developing robotic aircraft, inspired by birds, for a variety of missions covering reconnaissance and surveillance. Flapping wing aircraft concepts have been put forth in light of the efficiency of flapping flight at small scales. These aircraft are naturally equipped with the ability to rotate their wings about the root, a form of wing articulation. This thesis covers some problems concerning the performance, stability and control of robotic aircraft with articulated wings in gliding flight. Specifically, we are interested in aircraft without a vertical tail, which would then use wing articulation for longitudinal as well as lateral-directional control. Although the dynamics and control of articulated wing aircraft share several common features with conventional fixed wing aircraft, the presence of wing articulation presents several unique benefits as well as limitations from the perspective of performance and control. One of the objective of this thesis is to understand these features using a combination of theoretical and numerical tools. The aircraft concept envisioned in this thesis uses the wing dihedral angles for longitudinal and lateral-directional control. Aircraft with flexible articulated wings are also investigated. We derive a complete nonlinear model of the flight dynamics incorporating dynamic CG location and the changing moment of inertia. We show that symmetric dihedral configuration, along with a conventional horizontal tail, can be used to control flight speed and flight path angle independently of each other. This characteristic is very useful for initiating an efficient perching maneuver. It is shown that wing dihedral angles alone can effectively regulate sideslip during rapid turns and generate a wide range of equilibrium turn rates while maintaining a constant flight speed and regulating sideslip. We compute the turning performance limitations that arise due to the use of wing dihedral for yaw control

Transport cross section for small-angle scattering

International Nuclear Information System (INIS)

D'yakonov, M.I.; Khaetskii, A.V.

1991-01-01

Classical mechanics is valid for describing potential scattering under the conditions (1) λ much-lt α and (2) U much-gt ℎυ/α, where λ is the de Broglie wavelength, α is the characteristic size of the scatterer, U is the characteristic value of the potential energy, and υ is the velocity of the scattered particle. The second of these conditions means that the typical value of the classical scattering angle is far larger than the diffraction angle λ/α. In this paper the authors show that this second condition need not hold in a derivation of the transport cross section. In other words, provided that the condition λ much-lt α holds, it is always possible to calculate the transport cross section from the expressions of classical mechanics, even in the region U approx-lt ℎυ/α, where the scattering is diffractive,and the differential cross section is greatly different from the classical cross section. The transport cross section is found from the classical expression even in the anticlassical case U much-lt ℎυ/α, where the Born approximation can be used

Survival and Growth of Cottonwood Clones After Angle Planting and Base Angle Treatments

Science.gov (United States)

W.K. Randall; Harvey E. Kennedy

1976-01-01

Presently, commercial cottonwood plantations in the lower Mississippi Valley are established using vertically planted, unrooted cuttings with a flat (90°) base. Neither survival nor first-year growth of a group of six Stoneville clones was improved by angle planting or cutting base angles diagonally. For one clone, survival was significantly better when base angle was...

Two dialkylammonium salts of 2-amino-4-nitrobenzoic acid: crystal structures and Hirshfeld surface analysis

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James L. Wardell

2016-12-01

Full Text Available The crystal structures of two ammonium salts of 2-amino-4-nitrobenzoic acid are described, namely dimethylazanium 2-amino-4-nitrobenzoate, C2H8N+·C7H5N2O4−, (I, and dibutylazanium 2-amino-4-nitrobenzoate, C8H20N+·C7H5N2O4−, (II. The asymmetric unit of (I comprises a single cation and a single anion. In the anion, small twists are noted for the carboxylate and nitro groups from the ring to which they are connected, as indicated by the dihedral angles of 11.45 (13 and 3.71 (15°, respectively; the dihedral angle between the substituents is 7.9 (2°. The asymmetric unit of (II comprises two independent pairs of cations and anions. In the cations, different conformations are noted in the side chains in that three chains have an all-trans [(+-antiperiplanar] conformation, while one has a distinctive kink resulting in a (+-synclinal conformation. The anions, again, exhibit twists with the dihedral angles between the carboxylate and nitro groups and the ring being 12.73 (6 and 4.30 (10°, respectively, for the first anion and 8.1 (4 and 12.6 (3°, respectively, for the second. The difference between anions in (I and (II is that in the anions of (II, the terminal groups are conrotatory, forming dihedral angles of 17.02 (8 and 19.0 (5°, respectively. In each independent anion of (I and (II, an intramolecular amino-N—H...O(carboxylate hydrogen bond is formed. In the crystal of (I, anions are linked into a jagged supramolecular chain by charge-assisted amine-N—H...O(carboxylate hydrogen bonds and these are connected into layers via charge-assisted ammonium-N—H...O(carboxylate hydrogen bonds. The resulting layers stack along the a axis, being connected by nitro-N—O...π(arene and methyl-C—H...O(nitro interactions. In the crystal of (II, the anions are connected into four-ion aggregates by charge-assisted amino-N—H...O(carboxylate hydrogen bonding. The formation of ammonium-N—H...O(carboxylate hydrogen bonds, involving

Rapid protein fold determination using secondary chemical shifts and cross-hydrogen bond 15N-13C' scalar couplings (3hbJNC')

Energy Technology Data Exchange (ETDEWEB)

Bonvin, Alexandre M.J.J.; Houben, Klaartje; Guenneugues, Marc; Kaptein, Robert; Boelens, Rolf [Utrecht University, Bijvoet Center for Biomolecular Research, NMR Spectroscopy (Netherlands)

2001-11-15

The possibility of generating protein folds at the stage of backbone assignment using structural restraints derived from experimentally measured cross-hydrogen bond scalar couplings and secondary chemical shift information is investigated using as a test case the small {alpha}/{beta} protein chymotrypsin inhibitor 2. Dihedral angle restraints for the {phi} and {psi} angles of 32 out of 64 residues could be obtained from secondary chemical shift analysis with the TALOS program (Corneliscu et al., 1999a). This information was supplemented by 18 hydrogen-bond restraints derived from experimentally measured cross-hydrogen bond {sup 3hb}J{sub NC'} coupling constants. These experimental data were sufficient to generate structures that are as close as 1.0 A backbone rmsd from the crystal structure. The fold is, however, not uniquely defined and several solutions are generated that cannot be distinguished on the basis of violations or energetic considerations. Correct folds could be identified by combining clustering methods with knowledge-based potentials derived from structural databases.

Pair creation at large inherent angles

International Nuclear Information System (INIS)

Chen, P.; Tauchi, T.; Schroeder, D.V.

1992-01-01

In the next-generation linear colliders, the low-energy e + e - pairs created during the collision of high-energy e + e - beams would cause potential deleterious background problems to the detectors. At low collider energies, the pairs are made essentially by the incoherent process, where the pair is created by the interaction of beamstrahlung photons on the individual particles in the oncoming beam. This problem was first identified by Zolotarev, et al. At energies where the beamstrahlung parameter Υ lies approximately in the range 0.6 approx-lt Υ approx-lt 100, pair creation from the beamstrahlung photons is dominated by a coherent process, first noted by Chen. The seriousness of this pair creation problem lies in the transverse momenta that the pair particles carry when leaving the interaction point (IP) with large angles. Since the central issue is the transverse momentum for particles with large angles, the authors notice that there is another source for it. Namely, when the pair particles are created at low energies, the intrinsic angles of these pairs when produced may already be large. In this paper they reinvestigate the problem, following essentially the same equivalent photon approach, but with changes in specific details including the virtual photon spectrum. In addition, various assumptions are made more explicit. The formulas derived are then applied to the collider parameters designed by Palmer

The double Brewster angle effect

Science.gov (United States)

Thirion-Lefevre, Laetitia; Guinvarc'h, Régis

2018-01-01

The Double Brewster angle effect (DBE) is an extension of the Brewster angle to double reflection on two orthogonal dielectric surfaces. It results from the combination of two pseudo-Brewster angles occurring in complementary incidence angles domains. It can be observed for a large range of incidence angles provided that double bounces mechanism is present. As a consequence of this effect, we show that the reflection coefficient at VV polarization can be at least 10 dB lower than the reflection coefficient at HH polarization over a wide range of incidence angle - typically from 20 to 70∘. It is experimentally demonstrated using a Synthetic Aperture Radar (SAR) image that this effect can be seen on buildings and forests. For large buildings, the difference can reach more than 20 dB. xml:lang="fr"

Crystal structure of 1-[(6-chloropyridin-3-ylsulfonyl]-1,2,3,4-tetrahydroquinoline

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S. Jeyaseelan

2015-06-01

Full Text Available The tetrahydropyridine ring of the quinoline system in the title compound, C14H13ClN2O2S, adopts a half-chair conformation with the bond-angle sum at the N atom being 350.0°. The dihedral angle between the least-squares planes of the two aromatic rings is 50.13 (11°. In the crystal, inversion dimers linked by pairs of C—H...O hydrogen bonds generate R22(10 loops. Additional intermolecular C—H...O hydrogen bonds generate C(7 chains along [100].

2-Aminobenzoic acid–4-(pyridin-4-yldisulfanyl)pyridine (1/1)

OpenAIRE

Hadi D. Arman; Trupta Kaulgud; Edward R. T. Tiekink

2011-01-01

The title 1:1 co-crystal, C7H7NO2·C10H8N2S2, features a highly twisted 4-(pyridin-4-yldisulfanyl)pyridine molecule [dihedral angle between the pyridine rings = 89.06 (10)°]. A small twist is evident in the 2-aminobenzoic acid molecule, with the C—C—C—O torsion angle being −7.7 (3)°. An N—H...O hydrogen bond occurs in the 2-aminobenzoic acid molecule. In the crystal, molecules are linked by O&#...

(E-1-(1,3-Benzodioxol-5-yl-3-[4-(dimethylaminophenyl]prop-2-en-1-one

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Karthik Kumara

2017-01-01

Full Text Available In the title compound, C18H17NO3, the olefinic double bond adopts an E conformation. The molecule is nearly planar as indicated by the dihedral angle of 3.11 (6° between the benzodioxole and benzene rings. The carbonyl group lies in the plane of the olefinic double bond and the benzodioxole ring. The trans conformation of the C=C double bond in the central enone group is confirmed by the C=C—C—C torsion angle of −177.82 (14°.

(E-1-(3-Bromophenyl-3-(3-fluorophenylprop-2-en-1-one

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S. Rajendraprasad

2017-03-01

Full Text Available In the title compound, C15H10BrFO, the olefinic double bond adopts an E conformation. The molecule is non-planar as seen by the dihedral angle of 48.92 (11° between the bromophenyl and fluorophenyl rings. The carbonyl group is twisted from the plane of the bromophenyl ring and the olefinic double bond. The trans conformation of the C=C double bond in the central enone group is confirmed by the C—C=C—C torsion angle of −165.7 (2°.

Scattering angle base filtering of the inversion gradients

KAUST Repository

Alkhalifah, Tariq Ali

2014-01-01

Full waveform inversion (FWI) requires a hierarchical approach based on the availability of low frequencies to maneuver the complex nonlinearity associated with the problem of velocity inversion. I develop a model gradient filter to help us access the parts of the gradient more suitable to combat this potential nonlinearity. The filter is based on representing the gradient in the time-lag normalized domain, in which low scattering angles of the gradient update are initially muted. The result are long-wavelength updates controlled by the ray component of the wavefield. In this case, even 10 Hz data can produce near zero wavelength updates suitable for a background correction of the model. Allowing smaller scattering angle to contribute provides higher resolution information to the model.

Prospective case series on trabecular-iris angle status after an acute episode of phacomorphic angle closure

Directory of Open Access Journals (Sweden)

Jacky Lee

2013-02-01

Full Text Available AIM:To investigate the trabecular-iris angle with ultrasound biomicroscopy (UBM post cataract extraction after an acute attack of phacomorphic angle closure.METHODS: This prospective study involved 10 cases of phacomorphic angle closure that underwent cataract extraction and intraocular lens insertion after intraocular pressure (IOP lowering. Apart from visual acuity and IOP, the trabecular-iris angle was measured by gonioscopy and UBM at 3 months post attack.RESULTS: In 10 consecutive cases of acute phacomorphic angle closure from December 2009 to December 2010, gonioscopic findings showed peripheral anterior synechiae (PAS ≤ 90° in 30% of phacomorphic patients and a mean Shaffer grading of (3.1±1.0. UBM showed a mean angle of (37.1°±4.5° in the phacomorphic eye with the temporal quadrant being the most opened and (37.1°±8.0° in the contralateral uninvolved eye. The mean time from consultation to cataract extraction was (1.4±0.7 days and the mean total duration of phacomorphic angle closure was (3.6±2.8 days but there was no correlation to the degree of angle closure on UBM (Spearman correlation P=0.7. The presenting mean IOP was (50.5±7.4 mmHg and the mean IOP at 3 months was (10.5±3.4 mmHg but there were no correlations with the degree of angle closure (Spearman correlations P=0.9.CONCLUSION:An open trabecular-iris angle and normal IOP can be achieved after an acute attack of phacomorphic angle closure if cataract extraction is performed within 1 day - 2 days after IOP control. Gonioscopic findings were in agreement with UBM, which provided a more specific and object angle measurement. The superior angle is relatively more narrowed compared to the other quadrants. All contralateral eyes in this series had open angles.

Phacoemulsification with intraocular lens implantation in primary angle-closure suspect, primary angle-closure and primary angle-closure glaucoma with cataract

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Kun Zeng

2013-08-01

Full Text Available AIM: To evaluate the features and clinical outcomes of cataract extraction by phacoemulsification with intraocular lens implantation in primary angle-closure suspect(PACS, primary angle-closure(PACand primary angle-closure glaucoma(PACGwith cataract.METHODS:Phacoemulsification with intraocular lens implantation was performed on 86 cases(86 eyesdiagnosed as PACS, PAC and PACG co-existing cataract from January to December 2012. All cases were followed up for 3 months to 1 year. Pre-operative and post-operative visual acuity, intraocular pressure(IOP, gonioscopy, ultrasound biomicroscopy(UBM, visual field and usage of anti-glaucomaous eye drops were recorded.RESULTS:Zonular dialysis existed in 19 eyes(22%. The post-operative visual acuity improved in 84 eyes(98%. The post-operative visual acuity was CONCLUSION: PACS, PAC and PACG co-existing zonular dialysis is common. Phacoemulsification with IOL implantation can reduce IOP, deepen anterior chamber and open angle.

Sintering of Spherical Particles of Equal and Different Size Arranged in a Body Centered Cubic Structure

DEFF Research Database (Denmark)

Redanz, Pia; McMeeking, R. M.

2003-01-01

Solid-state sintering of a bcc structure of spherical particles has been studied numerically by use of simple shape parameters to describe the state of the unit cell. Both free and pressure-assisted sintering of particles of equal and different sizes for various ratios of boundary and surface dif......, different dihedral angles and the evolution of relative density and sintering stresses are studied....

N′-(3-Bromo-4-methoxybenzylidenenicotinohydrazide monohydrate

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Feng-Yu Bao

2009-09-01

Full Text Available In the title compound, C14H12BrN3O2·H2O, the benzene ring is oriented at a dihedral angle of 39.66 (11° with respect to the pyridine ring. The solvent water molecule links with the organic compound via O—H...O, O—H...N and N—H...O hydrogen bonding.

2-Benzyl-6-chloro-1-(4-methylphenyl-1H-indole-3-carbonitrile

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Qiao Yan

2011-12-01

Full Text Available In the title compound, C23H17ClN2, the dihedral angle between the indole ring and the attached tolyl ring is 86.97 (8°. Weak C—H...N(nitrile hydrogen bonding, and C—H...π(aromatic and short Cl...π(aromatic [3.628 (1 Å] interactions consolidate the crystal packing.

2-(4-Fluoroanilino-3-(2-hydroxyethylquinazolin-4(3H-one

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2009-03-01

Full Text Available The molecular and crystal structures of the title compound, C16H14FN3O2, are stabilized by intramolecular N—H...O and intermolecular O—H...O hydrogen bonds. The existence of non-classical intramolecular C—H...N hydrogen bonds provides a dihedral angle between the fluoro-substituted benzene and pyrimidinone rings of 7.9 (1°.

(E)-3-Hydr?oxy-13-methyl-16-[4-(methyl?sulfan?yl)benzyl?idene]-7,8,9,11,12,13,15,16-octa?hydro-6H-cyclo?penta?[a]phen?an????thren-17(14H)-one

OpenAIRE

Gunasekaran, B.; Murugan, R.; Narayanan, S. Sriman; Manivannan, V.

2008-01-01

In the title compound, C26H28O2S, the dihedral angles between the mean plane of the five membered ring and the 4-(methylsulfanyl)benzylidine ring in the two crystallographically independent molecules are 34.05 (10) and 40.53 (15)°. The packing is stabilized by intermolecular O—H...O and C—H...O interactions.

(E-3-Hydroxy-13-methyl-16-[4-(methylsulfanylbenzylidene]-7,8,9,11,12,13,15,16-octahydro-6H-cyclopenta[a]phenanthren-17(14H-one

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R. Murugan

2009-01-01

Full Text Available In the title compound, C26H28O2S, the dihedral angles between the mean plane of the five membered ring and the 4-(methylsulfanylbenzylidine ring in the two crystallographically independent molecules are 34.05 (10 and 40.53 (15°. The packing is stabilized by intermolecular O—H...O and C—H...O interactions.

Phenyl N-phenylcarbamate

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Durre Shahwar

2009-06-01

Full Text Available In the title compound, C13H11NO2, the aromatic rings are oriented at a dihedral angle of 42.52 (12°. The crystal structure is stabilized by intermolecular N—H...O hydrogen bonds, which form infinite one-dimensional polymeric chains extending along the a axis. C—H...π interactions between the aromatic rings are also present.

2,5-Dimethyl-1-phenylsulfonyl-1H-pyrrole-3,4-dicarbaldehyde

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2009-03-01

Full Text Available In the title compound, C14H13NO4S, the mean planes of the pyrrole and phenyl rings form a dihedral angle of 88.7 (1°. The aldehyde groups are slightly twisted from the pyrrole plane. In the crystal structure, molecules are linked into a three-dimensional framework by C—H...O hydrogen bonds.

Ethyl 2-allyl-2-(5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7-ylpent-4-enoate

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Mohamed El Hafi

2017-09-01

Full Text Available In the title molecule, C16H20N4O2, the dihedral angle between the planes of the fused rings is 2.26 (8°. In the crystal, [\\overline{2}10] chains of molecules linked by C—H...O and C—H...N hydrogen bonds arise, which are further linked by weak C—H...π interactions.

N,N′-Bis(2-thienylmethylenebenzene-1,4-diamine

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Nai-Wei Dong

2009-09-01

Full Text Available The Schiff base, C16H12N2S2, has been synthesized by refluxing an ethanolic solution of thiophene-2-carbaldehyde and benzene-1,4-diamine. The center of the benzene ring is located on a crystallographic center of inversion. The dihedral angle between the benzene and thiophene rings is 63.6 (1°.

Crystal structure of 5,5′-dibromo-3,3′-di-tert-butyl-6,6′-dimethylbiphenyl-2,2′-diol

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Rika Obata

2015-05-01

Full Text Available The whole molecule of the title compound, C22H28Br2O2, is generated by twofold rotation symmetry. The dihedral angle of the biphenyl moiety is 85.05 (11°. The hydroxy groups show intramolecular O—H...π interactions without any other hydrogen-bond acceptors. In the crystal, there are no other significant intermolecular interactions present.

On the combinatorial foundations of Regge-calculus

International Nuclear Information System (INIS)

Budach, L.

1989-01-01

Lipschitz-Killing curvatures of piecewise flat spaces are combinatorial analogues of Lipschitz-Killing curvatures of Riemannian manifolds. In the following paper rigorous combinatorial representations and proofs of all basic results for Lipschitz-Killing curvatures not using analytic arguments are given. The principal tools for an elementary representation of Regge calculus can be developed by means of basic properties of dihedral angles. (author)

(E-3-(4-Bromophenyl-1-(3,4-dichlorophenylprop-2-en-1-one

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Rajni Kant

2009-04-01

Full Text Available The molecule of the title compound, C15H9BrCl2O, is shown to be the E isomer, with the 3,4-dichlorobenzoyl and p-bromophenyl substituents in trans positions with respect to the chalcone olefin bond. The molecule is non-planar, the two aromatic rings forming a dihedral angle of 49.58 (1°.

2-(3-Hydroxybenzylaminoacetic acid

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Li-Hua Zhi

2011-07-01

Full Text Available There are two independent 2-(3-hydroxybenzylaminoacetic acid molecules, C9H11NO3, in the asymmetric unit of the title compound. The dihedral angle between the benzene rings of the two independent molecules is 58.12 (4°. The crystal packing is stablized by intermolecular O—H...O and N—H...O hydrogen bonds.

3-[4-(Dimethylaminophenyl]-1-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octahydronaphthalen-2-ylprop-2-en-1-one

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Moha Berraho

2011-01-01

Full Text Available The title compound, C23H31NO, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa (L Aiton [or Dittrichia Viscosa (L Greuter]. The cyclohexene ring has a half-chair conformation, whereas the cyclohexane ring displays a chair conformation. The dihedral angle between the latter ring and its substituent is 83.6 (7°.

1-[1-(4-Chloro-phen-yl)ethyl-idene]carbono-hydrazide.

Science.gov (United States)

Du, Lingyun; Du, Lei; Wang, Shuhao

2009-08-12

The mol-ecular skeleton of the title mol-ecule, C(9)H(11)ClN(4)O, is essentially planar, the dihedral angle between the ring and the and N/N/C plane being 6.7 (3)°. In the crystal, inter-molecular N-H⋯O and N-H⋯N hydrogen bonds link the mol-ecules into ribbons propagated along [010].

Effect of viewing angle on arm reaching while standing in a virtual environment: potential for virtual rehabilitation.

Science.gov (United States)

Ustinova, K I; Perkins, J; Szostakowski, L; Tamkei, L S; Leonard, W A

2010-02-01

Functional arm movements, such as reaching while standing, are planned and executed according to our perception of body position in space and are relative to environmental objects. The angle under which the environment is observed is one component used in creating this perception. This suggests that manipulation of viewing angle may modulate whole body movement to affect performance. We tested this by comparing its effect on reaching in a virtually generated environment. Eleven young healthy individuals performed forward and lateral reaches in the virtual environment, presented on a flat screen in third-person perspective. Participants saw a computer-generated model (avatar) of themselves standing in a courtyard facing a semi-circular hedge with flowers. The image was presented in five different viewing angles ranging from seeing the avatar from behind (0 degrees), to viewing from overhead (90 degrees). Participants attempted to touch the furthest flower possible without losing balance or stepping. Kinematic data were collected to analyze endpoint displacement, arm-postural coordination and center of mass (COM) displacement. Results showed that reach distance was greatest with angular perspectives of approximately 45-77.5 degrees , which are larger than those used in analogous real world situations. Larger reaches were characterized by increased involvement of leg and trunk body segments, altered inter-segmental coordination, and decreased inter-segmental movement time lag. Thus a viewing angle can be a critical visuomotor variable modulating motor coordination of the whole body and related functional performance. These results can be used in designing virtual reality games, in ergonomic design, teleoperation training, and in designing virtual rehabilitation programs that re-train functional movement in vulnerable individuals. Copyright 2009 Elsevier B.V. All rights reserved.

Small angle spectrometers: Summary

International Nuclear Information System (INIS)

Courant, E.; Foley, K.J.; Schlein, P.E.

1986-01-01

Aspects of experiments at small angles at the Superconducting Super Collider are considered. Topics summarized include a small angle spectrometer, a high contingency spectrometer, dipole and toroid spectrometers, and magnet choices

Demonstration of angle widening using EyeCam after laser peripheral iridotomy in eyes with angle closure.

Science.gov (United States)

Perera, Shamira A; Quek, Desmond T; Baskaran, Mani; Tun, Tin A; Kumar, Rajesh S; Friedman, David S; Aung, Tin

2010-06-01

To evaluate EyeCam in detecting changes in angle configuration after laser peripheral iridotomy (LPI) in comparison to gonioscopy, the reference standard. Prospective comparative study. Twenty-four subjects (24 eyes) with primary angle-closure glaucoma (PACG) were recruited. Gonioscopy and EyeCam (Clarity Medical Systems) imaging of all 4 angle quadrants were performed, before and 2 weeks after LPI. Images were graded according to angle structures visible by an observer masked to clinical data or the status of LPI, and were performed in a random order. Angle closure in a quadrant was defined as the inability to visualize the posterior trabecular meshwork. We determined the number of quadrants with closed angles and the mean number of clock hours of angle closure before and after LPI in comparison to gonioscopy. Using EyeCam, all 24 eyes showed at least 1 quadrant of angle widening after LPI. The mean number of clock hours of angle closure decreased significantly, from 8.15 +/- 3.47 clock hours before LPI to 1.75 +/- 2.27 clock hours after LPI (P gonioscopy showed 1.0 +/- 1.41 (95% CI, 0.43-1.57) quadrants opening from closed to open after LPI compared to 2.0 +/- 1.28 (95% CI, 1.49-2.51, P = .009) quadrants with EyeCam. Intra-observer reproducibility of grading the extent of angle closure in clock hours in EyeCam images was moderate to good (intraclass correlation coefficient 0.831). EyeCam may be used to document changes in angle configuration after LPI in eyes with PACG. Copyright 2010 Elsevier Inc. All rights reserved.

Measure of back angle cross sections of antiproton-nucleus elastic scattering at 48 and 180 MeV

International Nuclear Information System (INIS)

Berrada, M.

1986-04-01

Antiproton-nucleus elastic scattering was studied in the LEAR ring at CERN. The scattering cross section at back angles (θ LAB = 142 to 164 deg inclusive) was measured using plastic scintillation detectors. Analysis of experimental data at 47 MeV for a CH target and at 182 MeV for CH, C12, 016, and 018 targets produces differential cross sections for back angles less than or equal to a few dozen microbarns. These results agree with theoretical microscopic predictions. The analysis improves understanding of antiproton-nucleus interaction and introduces a constraint on the construction of optical potentials. The antiproton-nucleus potential is shown to be highly absorbing, thereby excluding S type potentials, and removing the ambiguity arising from the analysis of antiprotonic atoms. The results also show that there is no attractive pocket in the real potential likely to lead to an increase of the back angle cross sections [fr

Synthesis of functional nanomaterials via colloidal mask templating and glancing angle deposition (GLAD)”

DEFF Research Database (Denmark)

Dolatshahi-Pirouz, Alireza; Jensen, Thomas Bo; Vorup-Jensen, Thomas

2010-01-01

We present a simple method for the fabrication of separated brush-like networks with both improved optical and biological properties. The brush networks were fabricated by combing the glancing angle deposition (GLAD) technique with colloidal mask templating. By changing the deposition angle durin...... of multifunctional nanomaterials which could have potential impact on devices where both controlled optical properties and cell surface interactions are needed (for instance controlled cell adhesion on optical biosensor materials).......We present a simple method for the fabrication of separated brush-like networks with both improved optical and biological properties. The brush networks were fabricated by combing the glancing angle deposition (GLAD) technique with colloidal mask templating. By changing the deposition angle during...

Behavior of Tilted Angle Shear Connectors

Science.gov (United States)

Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

2015-01-01

According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

Behavior of Tilted Angle Shear Connectors.

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Koosha Khorramian

Full Text Available According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

N-(1,3-Dioxo-2,3-dihydro-1H-isoindol-2-yl-4,4′′-difluoro-5′-hydroxy-1,1′:3′,1′′-terphenyl-4′-carboxamide

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Hoong-Kun Fun

2012-09-01

Full Text Available The asymmetric unit of the title compound, C27H16F2N2O4, consists of two crystallographically independent molecules (A and B. In molecule B, the isoindoline-1,3-dione ring system is disordered over two set of sites with a site-occupancy ratio of 0.658 (12:0.342 (12. In molecule A, the fluoro-substituted benzene rings make dihedral angles of 18.36 (8 and 46.37 (8° with the central benzene ring, whereas the corresponding angles are 40.90 (8 and 52.89 (9° in molecule B. The isoindoline ring system in molecule A and the major and minor components of the disordered isoindoline ring system in molecule B make dihedral angles of 58.50 (4, 54.13 (16 and 70.01 (28 °, respectively, with their attached benzene rings, linked through the amide group. An intramolecular O—H...O hydrogen bond generates an S(6 ring in each molecule. In the crystal, molecules are linked by N—H...O, C—H...F and C—H...O hydrogen bonds into sheets lying parallel to the bc plane. The crystal studied was a non-merohedral twin with a refined twin component ratio of 0.9316 (8:0.0684 (8.

Carpal angles as measured on CT and MRI: can we simply translate radiographic measurements?

Energy Technology Data Exchange (ETDEWEB)

Tan, Stephanie; Ghumman, Simranjit S.; Moser, Thomas P. [Hopital Notre-Dame (CHUM), Department of Radiology, Centre Hospitalier de l' Universite de Montreal, Montreal, QC (Canada); Ladouceur, Martin [Research Center CHUM, Montreal, QC (Canada)

2014-12-15

To determine the reliability of carpal angles measured on CT and MRI compared to radiography and assess if these measurements are interchangeable. Our institutional ethic research committee approved this study. For this retrospective study, two independent observers measured the scapholunate (SL), capitolunate (CL), radiolunate (RL), and radioscaphoid (RS) angles on 21 sets of exams, with each set including a radiograph, CT, and MRI of the same wrist. Inter- and intra-observer agreements were evaluated with the intraclass correlation coefficient (ICC). Linear mixed models and two-way contingency tables were used to determine if the angles measured on cross-sectional modalities were significantly different from those obtained on radiography. Inter-observer agreement was strong (ICC >0.8) for all angles, except for the RL angle measured on MRI (ICC 0.68). Intra-observer agreement was also strong for all angles, except for the CL angle measured on CT (ICC 0.66). SL angles measured on CT and MRI were not statistically different from those measured on radiographs (p = 0.37 and 0.36, respectively), unlike CL, RL, and RS angles (p < 0.05). Accuracy between modalities varied between 76 and 86 % for the SL angle and ranged between 43 and 76 % for the other angles. CL, RL, and RS angles showed large intermodality variability. Therefore, their measurements on CT or MRI could potentially lead to miscategorization. Conversely, our data showing no significant difference between modalities, SL angle could be measured on CT and MRI to assess wrist instability with a lower risk of error. (orig.)

The impact of inlet angle and outlet angle of guide vane on pump in reversal based hydraulic turbine performance

International Nuclear Information System (INIS)

Shi, F X; Yang, J H; Wang, X H; Zhang, R H; Li, C E

2012-01-01

In this paper, in order to research the impact of inlet angle and outlet angle of guide vane on hydraulic turbine performance, a centrifugal pump in reversal is adopted as turbine. A numerical simulation method is adopted for researching outer performance and flow field of turbine. The results show: inlet angle has a crucial role to turbine, to the same flow, there is a noticeable decline for the efficiency and head of turbine with the inlet angle increases. At the best efficiency point(EFP),to a same inlet angle, when the inlet angle greater than inlet angle, velocity circulation in guide vane outlet decreases, which lead the efficiency of turbine to reduce, Contrarily, the efficiency rises. With the increase of inlet angle and outlet angle, the EFP moves to the big flow area and the uniformity of pressure distribution becomes worse. The paper indicates that the inlet angle and outlet angle have great impact on the turbine performance, and the best combination exists for the inlet angle and outlet angle of the guide vane.

Dielectric-based subwavelength metallic meanders for wide-angle band absorbers.

Science.gov (United States)

Shen, Su; Qiao, Wen; Ye, Yan; Zhou, Yun; Chen, Linsen

2015-01-26

We propose nano-meanders that can achieve wide-angle band absorption in visible regime. The nano-meander consists of a subwavelength dielectric grating covered by continuous ultra-thin Aluminum film (less than one tenth of the incident wavelength). The excited photonic resonant modes, such as cavity mode, surface plasmonic mode and Rayleigh-Wood anomaly, are discussed in detail. Nearly total resonant absorption due to funneling mechanism in the air nano-groove is almost invariant with large incident angle in transverse magnetic polarization. From both the structural geometry and the nanofabrication point of view, the light absorber has a very simple geometrical structure and it is easy to be integrated into complex photonic devices. The highly efficient angle-robust light absorber can be potential candidate for a range of passive and active photonic applications, including solar-energy harvesting as well as producing artificial colors on a large scale substrate.

Difference structures from time-resolved small-angle and wide-angle x-ray scattering

Science.gov (United States)

Nepal, Prakash; Saldin, D. K.

2018-05-01

Time-resolved small-angle x-ray scattering/wide-angle x-ray scattering (SAXS/WAXS) is capable of recovering difference structures directly from difference SAXS/WAXS curves. It does so by means of the theory described here because the structural changes in pump-probe detection in a typical time-resolved experiment are generally small enough to be confined to a single residue or group in close proximity which is identified by a method akin to the difference Fourier method of time-resolved crystallography. If it is assumed, as is usual with time-resolved structures, that the moved atoms lie within the residue, the 100-fold reduction in the search space (assuming a typical protein has about 100 residues) allows the exaction of the structure by a simulated annealing algorithm with a huge reduction in computing time and leads to a greater resolution by varying the positions of atoms only within that residue. This reduction in the number of potential moved atoms allows us to identify the actual motions of the individual atoms. In the case of a crystal, time-resolved calculations are normally performed using the difference Fourier method, which is, of course, not directly applicable to SAXS/WAXS. The method developed in this paper may be thought of as a substitute for that method which allows SAXS/WAXS (and hence disordered molecules) to also be used for time-resolved structural work.

Crystal structures of 4-methoxy-N-(4-methylphenylbenzenesulfonamide and N-(4-fluorophenyl-4-methoxybenzenesulfonamide

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Vinola Z. Rodrigues

2015-11-01

Full Text Available Crystal structures of two N-(arylarylsulfonamides, namely, 4-methoxy-N-(4-methylphenylbenzenesulfonamide, C14H15NO3S, (I, and N-(4-fluorophenyl-4-methoxybenzenesulfonamide, C13H12FNO3S, (II, were determined and analyzed. In (I, the benzenesulfonamide ring is disordered over two orientations, in a 0.516 (7:0.484 (7 ratio, which are inclined to each other at 28.0 (1°. In (I, the major component of the sulfonyl benzene ring and the aniline ring form a dihedral angle of 63.36 (19°, while in (II, the planes of the two benzene rings form a dihedral angle of 44.26 (13°. In the crystal structure of (I, N—H...O hydrogen bonds form infinite C(4 chains extended in [010], and intermolecular C—H...πaryl interactions link these chains into layers parallel to the ab plane. The crystal structure of (II features N—H...O hydrogen bonds forming infinite one dimensional C(4 chains along [001]. Further, a pair of C—H...O intermolecular interactions consolidate the crystal packing of (II into a three-dimensional supramolecular architecture.

5-(4-Bromophenyl-2-(3,4-methylenedioxyphenyl-3-methylsulfanyl-1-benzofuran

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Hong Dae Choi

2009-10-01

Full Text Available The title compound, C22H15BrO3S, crystallizes with four molecules in the asymmetric unit. The 4-bromophenyl rings are rotated out of the benzofuran planes, with dihedral angles for the four molecules of 20.8 (2, 17.8 (2, 23.5 (4 and 23.9 (4°. The dihedral angles between the 3,4-methylenedioxyphenyl ring and the benzofuran plane are 13.5 (2, 7.1 (2, 18.6 (3 and 14.2 (3° in the four molecules. The crystal structure is stabilized by weak nonclassical intermolecular C—H...O hydrogen bonds. The crystal structure also exhibits intermolecular aromatic π–π interactions between the benzene and furan rings and between the 4-bromophenyl and 3,4-methylenedioxyphenyl rings from molecules of the same type; the centroid–centroid distances are 3.92 (1 and 3.79 (1, 3.91 (1, 3.77 (1 and 3.77 (1, and 3.79 (1 and 3.75 (1Å in the four molecules.

A TQFT of Tuarev-Viro type on shaped triangulations

Energy Technology Data Exchange (ETDEWEB)

Kashaev, Rinat [Geneva Univ. (Switzerland); Luo, Feng [Rutgers Univ., Piscataway, NJ (United States). Dept. of Mathematics; Vartanov, Grigory [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2012-10-15

A shaped triangulation is a finite triangulation of an oriented pseudo three manifold where each tetrahedron carries dihedral angles of an ideal hyberbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3-2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann-Zagier Poisson bracket. Similarly to Turaev-Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed 3-manifolds, our partition function is twice the absolute value squared of the partition function of Techmueller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev-Viro and the Witten-Reshetikhin-Turaev invariants of three manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.

4,4′-([4,4′-Bipyridine]-1,1′-diium-1,1′-diyldibenzoate dihydrate

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Mark A. Rodriguez

2016-06-01

Full Text Available We report here the synthesis of a neutral viologen derivative, C24H16N2O4·2H2O. The non-solvent portion of the structure (Z-Lig is a zwitterion, consisting of two positively charged pyridinium cations and two negatively charged carboxylate anions. The carboxylate group is almost coplanar [dihedral angle = 2.04 (11°] with the benzene ring, whereas the dihedral angle between pyridine and benzene rings is 46.28 (5°. The Z-Lig molecule is positioned on a center of inversion (Fig. 1. The presence of the twofold axis perpendicular to the c-glide plane in space group C2/c generates a screw-axis parallel to the b axis that is shifted from the origin by 1/4 in the a and c directions. This screw-axis replicates the molecule (and solvent water molecules through space. The Z-Lig molecule links to adjacent molecules via O—H...O hydrogen bonds involving solvent water molecules as well as intermolecular C—H...O interactions. There are also π–π interactions between benzene rings on adjacent molecules.

Two-Photon Absorption Properties of Gold Fluorescent Protein: A Combined Molecular Dynamics and Quantum Chemistry Study.

Science.gov (United States)

Simsek, Yusuf; Brown, Alex

2018-05-09

Molecular dynamic (MD) simulations were carried out to obtain the conformational changes of the chromophore in the gold fluorescent protein (PDB ID: 1OXF). To obtain two-photon absorption (TPA) cross-sections, time dependent density functional theory (TD-DFT) computations were performed for chromophore geometries sampled along the trajectory. The TD-DFT computations used the CAM-B3LYP functional and 6-31+G(d) basis set with the conductor-like polarizable continuum model (PCM) with parameters for water. Results showed that two dihedral angles change remarkably over the simulation time. TPA cross-sections were found to average 20 GM for the excitation to S1 between 430 and 460 nm; however, the maximal and minimal values were 35GM and 5GM, respectively. Besides the effects of the dihedrals on the spectroscopic properties, some bond lengths affected the excitation energies and the TPA cross-sections significantly (up to ±25-30%) while the effects of bond angles were smaller (±5%). Overall the present results provide insight in the effects of conformational exibility on TPA (with gold fluorescent protein as a specific example) and suggest that further experimental measurements of TPA for gold fluorescent protein should be undertaken.

Bis{μ-4,4′-dimethoxy-2,2′-[propane-1,2-diylbis(nitrilomethylidyne]diphenolato}bis({4,4′-dimethoxy-2,2′-[propane-1,2-diylbis(nitrilomethylidyne]diphenol}manganese(III bis(hexafluoridophosphate

Directory of Open Access Journals (Sweden)

Mohammad Hossein Habibi

2009-08-01

Full Text Available In the title complex, [Mn2(C19H20N2O42(C19H22N2O42](PF62, the MnIII ion is coordinated by two O [Mn—O = 1.855 (2 and 1.887 (2 Å] and two N [Mn—N = 1.982 (3 and 1.977 (3 Å] atoms from the tetradentate Schiff base ligand and a coordinated axial ligand [Mn—O = 2.129 (2 Å]. The centrosymmetric dimer contains two Jahn–Teller-distorted MnIII ions, each in a nearly octahedral geometry, connected through two phenolate bridges from two ligands. There are two stereogenic centers. The methyl group and the H atom attached to the middle propane C atom are disordered over two positions with occupancy factors in the ratio 0.58:0.42. The crystal is therefore a mixture of two diasteroisomers, viz. RS/SR and RR/SS. In the axial ligand, the two benzene rings form a dihedral angle of 56.97 (5° and the dihedral angle between the two MnNC3O chelate rings is 2.98 (12°

Crystal structure of trans-diaquabis(4-cyanobenzoato-κObis(nicotinamide-κN1cobalt(II

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Gülçin Şefiye Aşkın

2015-05-01

Full Text Available In the title complex, [Co(C8H4NO22(C6H6N2O2(H2O2], the CoII atom is located on an inversion centre and is coordinated by two 4-cyanobenzoate (CNB anions, two nicotinamide (NA ligands and two water molecules. The four O atoms in the equatorial plane form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination sphere is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxylate group and the adjacent benzene ring is 22.11 (15°, while the pyridine and benzene rings are oriented at a dihedral angle of 89.98 (5°. In the crystal, intermolecular N—H...O and O—H...O hydrogen bonds link the molecules, enclosing R22(8 and R44(8 ring motifs, forming layers parallel to (100. The layers are linked via C—H...O and C—H...N hydrogen bonds, resulting in a three-dimensional network. A weak C—H...π interaction is also observed.

tert-Butyl 2-methyl-2-(4-nitrobenzoylpropanoate

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Chelsey M. Crosse

2010-02-01

Full Text Available The title compound, C15H19NO5, is bent with a dihedral angle of 61.8 (2° between the mean planes of the benzene ring and a group encompassing the ester functionality (O=C—O—C. The dihedral angle of 0.8 (2° between the mean planes of the nitro group and the benzene ring indicates near coplanarity. In the crystal, each molecule is linked to four adjacent molecules by weak C—H...O hydrogen-bonding interactions. Both benzene H atoms ortho to the ketone O atom form C—H...O hydrogen bonds with the keto O atoms of two neighboring molecules (of the keto and ester groups, respectively, and the two other interactions involve the H atoms from a methyl group of the dimethyl residue, displaying C—H...O interactions with the O atoms of the nitro groups. These four interactions for each molecule lead to the formation of two-dimensional sheets with a hydrophilic interior, held together by weak hydrogen-bonded interactions, and a hydrophobic exterior composed of protruding methyl groups which interstack with the methyl groups in adjacent sheets.

A TQFT of Tuarev-Viro type on shaped triangulations

International Nuclear Information System (INIS)

Kashaev, Rinat; Luo, Feng

2012-10-01

A shaped triangulation is a finite triangulation of an oriented pseudo three manifold where each tetrahedron carries dihedral angles of an ideal hyberbolic tetrahedron. To each shaped triangulation, we associate a quantum partition function in the form of an absolutely convergent state integral which is invariant under shaped 3-2 Pachner moves and invariant with respect to shape gauge transformations generated by total dihedral angles around internal edges through the Neumann-Zagier Poisson bracket. Similarly to Turaev-Viro theory, the state variables live on edges of the triangulation but take their values on the whole real axis. The tetrahedral weight functions are composed of three hyperbolic gamma functions in a way that they enjoy a manifest tetrahedral symmetry. We conjecture that for shaped triangulations of closed 3-manifolds, our partition function is twice the absolute value squared of the partition function of Techmueller TQFT defined by Andersen and Kashaev. This is similar to the known relationship between the Turaev-Viro and the Witten-Reshetikhin-Turaev invariants of three manifolds. We also discuss interpretations of our construction in terms of three-dimensional supersymmetric field theories related to triangulated three-dimensional manifolds.

(4′-Acetyloxy-1,3,1′-trioxo-1,3,4,4a,4b,5,6,7,9,9a-decahydrospiro[indene-2,9′-pyrano[4,3-a]pyrrolizin]-3′-ylmethyl acetate

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S. Lakshmi

2013-12-01

Full Text Available In the title compound, C23H23NO8, the dihedral angle between the five- and six-membered rings of the indene-dione moiety is 3.09 (13°. The mean plane of the five-membered ring (which has a flat envelope conformation with the spiro C atom as the flap is inclined to the mean plane of the central five-membered ring of the pyrrolizine unit by 76.48 (12°. This central ring has a twist conformation on the N—C(spiro bond. The outer ring of the pyrrolizine unit has an envelope conformation with the N atom as the flap. The mean planes of these two fused rings are inclined to one another by 65.28 (15°. The pyran ring has a screw-boat conformation and its mean plane makes a dihedral angle of 29.50 (11° with the mean plane of the central five-membered ring of the pyrrolizine unit. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming two-dimensional networks lying parallel to the ab plane.

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese.

Science.gov (United States)

Wang, Ye Elaine; Li, Yingjie; Wang, Dandan; He, Mingguang; Lin, Shan

2013-11-21

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese. This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature. In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians. Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Crystal structure of 2,3-bis(4-methylphenylbenzo[g]quinoxaline

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Young-Inn Kim

2018-04-01

Full Text Available The title compound, C26H20N2, was obtained during a search for new π-extended ligands with the potential to generate efficient phosphors with iridium(III for organic light-emitting devices (OLEDs. The benzoquinoxaline ring system is almost planar (r.m.s. deviation = 0.076 Å. A pseudo-twofold rotation axis runs through the midpoints of the C2—C3 and C9—C10 bonds. The two phenyl rings are twisted relative to the benzoquinoxaline ring system, making dihedral angles of 53.91 (4 and 36.86 (6°. In the crystal, C—H...π (arene interactions link the molecules, but no π–π interactions between aromatic rings are observed.

1-Phenyl-5-{[2-(trimethylsilylethyl]sulfonyl}-1H-tetrazole

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David Tymann

2011-09-01

Full Text Available The title compound, C12H18N4O2SSi, was synthesized to be employed in a Julia–Kocieński olefination. In the molecule, the dihedral angle between the phenyl ring and the tetrazole ring is 41.50 (5°. The significantly longer Si—C(methylene bond [1.8786 (13 Å] and the shortened adjacent C—C bond [1.5172 (18 Å], as well as the significant deviation of the corresponding Si—C—C angle [114.16 (9°] from the ideal tetrahedral angle, can be attributed to the β-effect of silicon. In the crystal, molecules are held together by van der Waals interactions.

Exfoliation of GaAs caused by MeV 1H and 4He ion implantation at left angle 100 right angle , left angle 110 right angle axial and random orientations

International Nuclear Information System (INIS)

Rauhala, E.; Raeisaenen, J.

1994-01-01

The exfoliation procedure of the ion range determination of gaseous implants in single crystal GaAs is investigated. The correlation of the observed crater depth with the ion range is studied for random, left angle 100 right angle and left angle 110 right angle axial orientation high dose implantations of 1.5-2.5 MeV 1 H and 4 He ions. Depending on the experimental conditions, the crater depths corresponded to range values between the modal range and the range maximum. The observed crater depths could be related to the actual He concentration depth distributions by determining the profiles of the 4 He implants by 2.7 MeV proton backscattering. The implantation parameters affecting the exfoliation process, and especially the increase rate of the sample temperature, are investigated. The range distribution parameters for the 1.5 MeV 4 He implants are presented. ((orig.))

Origami-inspired metamaterial absorbers for improving the larger-incident angle absorption

International Nuclear Information System (INIS)

Shen, Yang; Pang, Yongqiang; Wang, Jiafu; Ma, Hua; Pei, Zhibin; Qu, Shaobo

2015-01-01

When a folded resistive patch array stands up on a metallic plane, it can exhibit more outstanding absorption performance. Our theoretical investigations and simulations demonstrated that the folded resistive patch arrays can enhance the absorption bandwidth progressively with the increase of the incident angle for the oblique transverse magnetic incidence, which is contrary to the conventional resistive frequency selective surface absorber. On illumination, we achieved a 3D structure metamaterial absorber with the folded resistive patches. The proposed absorber is obtained from the inspiration of the origami, and it has broadband and lager-incident angle absorption. Both the simulations and the measurements indicate that the proposed absorber achieves the larger-incident angle absorption until 75° in the frequency band of 3.6–11.4 GHz. In addition, the absorber is extremely lightweight. The areal density of the fabricated sample is about 0.023 g cm −2 . Due to the broadband and lager-incident angle absorption, it is expected that the absorbers may find potential applications such as stealth technologies and electromagnetic interference. (paper)

Wafer scale oblique angle plasma etching

Science.gov (United States)

Burckel, David Bruce; Jarecki, Jr., Robert L.; Finnegan, Patrick Sean

2017-05-23

Wafer scale oblique angle etching of a semiconductor substrate is performed in a conventional plasma etch chamber by using a fixture that supports a multiple number of separate Faraday cages. Each cage is formed to include an angled grid surface and is positioned such that it will be positioned over a separate one of the die locations on the wafer surface when the fixture is placed over the wafer. The presence of the Faraday cages influences the local electric field surrounding each wafer die, re-shaping the local field to be disposed in alignment with the angled grid surface. The re-shaped plasma causes the reactive ions to follow a linear trajectory through the plasma sheath and angled grid surface, ultimately impinging the wafer surface at an angle. The selected geometry of the Faraday cage angled grid surface thus determines the angle at with the reactive ions will impinge the wafer.

A study on the contact angles of a water droplet on smooth and rough solid surfaces

International Nuclear Information System (INIS)

Park, Ju Young; Ha, Man Yeong; Choi, Ho Jin; Hong, Seung Do; Yoon, Hyun Sik

2011-01-01

We investigated the wetting characteristics such as contact angle, wetting radius and topography of water droplets on smooth and random solid surfaces. Molecular dynamic simulation is employed to analyze the wetting behavior of water droplets on smooth and rough surfaces by considering different potential energy models of bond, angle, Lennard-Jones and Coulomb to calculate the interacting forces between water molecules. The Lennard-Jones potential energy model is adopted as an interaction model between water molecules and solid surface atoms. The randomly rough surface is generated by changing the standard deviation of roughness height from 1 A to 3 A with the fixed autocorrelation length. The size of water droplet considered is in the range from 2,000 to 5,000 molecules. The contact angles increase generally with increasing number of water molecules. For a hydrophobic surface whose characteristic energy is 0.1 kcal/mol, the contact angles depend rarely on the standard deviation of the roughness height. However, when the surface energy is 0.5 and 1.0 kcal/mol, the contact angles depend on both the roughness height of surfaces and droplet size

Angles in hyperbolic lattices

DEFF Research Database (Denmark)

Risager, Morten S.; Södergren, Carl Anders

2017-01-01

It is well known that the angles in a lattice acting on hyperbolic n -space become equidistributed. In this paper we determine a formula for the pair correlation density for angles in such hyperbolic lattices. Using this formula we determine, among other things, the asymptotic behavior of the den......It is well known that the angles in a lattice acting on hyperbolic n -space become equidistributed. In this paper we determine a formula for the pair correlation density for angles in such hyperbolic lattices. Using this formula we determine, among other things, the asymptotic behavior...... of the density function in both the small and large variable limits. This extends earlier results by Boca, Pasol, Popa and Zaharescu and Kelmer and Kontorovich in dimension 2 to general dimension n . Our proofs use the decay of matrix coefficients together with a number of careful estimates, and lead...

Optimum Tilt Angle at Tropical Region

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S Soulayman

2015-02-01

Full Text Available : One of the important parameters that affect the performance of a solar collector is its tilt angle with the horizon. This is because of the variation of tilt angle changes the amount of solar radiation reaching the collector surface. Meanwhile, is the rule of thumb, which says that solar collector Equator facing position is the best, is valid for tropical region? Thus, it is required to determine the optimum tilt as for Equator facing and for Pole oriented collectors. In addition, the question that may arise: how many times is reasonable for adjusting collector tilt angle for a definite value of surface azimuth angle? A mathematical model was used for estimating the solar radiation on a tilted surface, and to determine the optimum tilt angle and orientation (surface azimuth angle for the solar collector at any latitude. This model was applied for determining optimum tilt angle and orientation in the tropical zones, on a daily basis, as well as for a specific period. The optimum angle was computed by searching for the values for which the radiation on the collector surface is a maximum for a particular day or a specific period. The results reveal that changing the tilt angle 12 times in a year (i.e. using the monthly optimum tilt angle maintains approximately the total amount of solar radiation near the maximum value that is found by changing the tilt angle daily to its optimum value. This achieves a yearly gain in solar radiation of 11% to 18% more than the case of a solar collector fixed on a horizontal surface.

Optimization of partial multicanonical molecular dynamics simulations applied to an alanine dipeptide in explicit water solvent.

Science.gov (United States)

Okumura, Hisashi

2011-01-07

The partial multicanonical algorithm for molecular dynamics and Monte Carlo simulations samples a wide range of an important part of the potential energy. Although it is a strong technique for structure prediction of biomolecules, the choice of the partial potential energy has not been optimized. In order to find the best choice, partial multicanonical molecular dynamics simulations of an alanine dipeptide in explicit water solvent were performed with 15 trial choices for the partial potential energy. The best choice was found to be the sum of the electrostatic, Lennard-Jones, and torsion-angle potential energies between solute atoms. In this case, the partial multicanonical simulation sampled all of the local-minimum free-energy states of the P(II), C(5), α(R), α(P), α(L), and C states and visited these states most frequently. Furthermore, backbone dihedral angles ϕ and ψ rotated very well. It is also found that the most important term among these three terms is the electrostatic potential energy and that the Lennard-Jones term also helps the simulation to overcome the steric restrictions. On the other hand, multicanonical simulation sampled all of the six states, but visited these states fewer times. Conventional canonical simulation sampled only four of the six states: The P(II), C(5), α(R), and α(P) states.

5-Bromo-3-(4-chlorophenylsulfinyl-2-methyl-1-benzofuran

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Hong Dae Choi

2010-11-01

Full Text Available In the title compound, C15H10BrClO2S, the 4-chlorophenyl ring is oriented approximately perpendicular to the mean plane of the benzofuran ring [dihedral angle = 89.55 (9°]. In the crystal, molecules are linked through weak intermolecular C—H...O hydrogen bonds and and a Br...Br contact [3.783 (3 Å].

1-(3-Methoxyphenyl-2-(phenylsulfonylethan-1-one

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Sammer Yousuf

2012-08-01

Full Text Available In the title compound, C15H14O4S, the dihedral angle between the benzene and phenyl rings is 88.74 (10°. In the crystal, molecules are linked into a three-dimensional network by C—H...O hydrogen bonds and π–π stacking interactions [centroid–centroid distances = 3.6092 (13–3.8651 (13 Å].

3-Methyl-4-(3-methylphenyl-5-(2-pyridyl-4H-1,2,4-triazole

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Dun-Ru Zhu

2009-05-01

Full Text Available In the molecule of the title compound, C15H14N4, the triazole ring is oriented at dihedral angles of 30.8 (2 and 67.4 (2° with respect to the pyridine and benzene rings, respectively. The crystal structure is stabilized by C—H...N hydrogen-bonding interactions, forming chains of molecules along [overline{1}01].

Ethyl 2-[4-(benzyloxyanilino]-4-oxo-4,5-dihydrofuran-3-carboxylate

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S. Sriman Narayanan

2008-12-01

Full Text Available In the title compound, C20H19NO5, the dihydrofuran ring is almost planar [maximum deviation of 0.021 (2°] and makes dihedral angles of 28.1 (7 and 54.5 (5° with the benzyl and phenylamino rings, respectively. The molecular packing is stabilized by intramolecular N—H...O hydrogen bonds and intermolecular C—H...O interactions.

1,5-Bis(4-chlorophenyl-3-[4-(dimethylaminophenyl]pentane-1,5-dione

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2009-03-01

Full Text Available In the title molecule, C25H23Cl2NO2, the central benzene ring forms dihedral angles of 81.88 (7 and 89.22 (7° with the two 4-chlorophenyl fragments. The crystal packing exhibits weak intermolecular C—H...O hydrogen bonds and π–π interactions [centroid–centroid distance 3.724 (3 Å].

2-[3-(4-Methoxyphenyl-1-phenyl-1H-pyrazol-5-yl]phenol

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2009-03-01

Full Text Available The title compound, C22H18N2O2, was derived from 1-(2-hydroxyphenyl-3-(4-methoxyphenylpropane-1,3-dione. The central pyrazole ring forms dihedral angles of 16.83 (5, 48.97 (4 and 51.68 (4°, respectively, with the methoxyphenyl, phenyl and hydroxyphenyl rings. The crystal packing is stabilized by O—H...N hydrogen bonding.

Structure determination of cyclo pentane terpene derivatives by crossed NMR and MS techniques

Energy Technology Data Exchange (ETDEWEB)

Pianet, I.; Bourgeois, G. [Bordeaux-1 Univ., 33 - Talence (France); Dolatkhani, M.; Cramail, H.; Deffieux, A. [Centre National de la Recherche Scientifique (CNRS), 33 - Talence (France)

1995-10-01

3 of the 4 stereoisomers of the 1-isopropenyl 2,3-dimethylcyclopentane, obtained from the cracking of 3,7-dimethylocta-1,6-diene, were purified and characterized. Dihedral angles, between the protons of the substituted carbons, have been determined by molecular modelling. Analysis of the NMR and mass spectra allowed us to access to the structure of the different isomers. (authors). 6 refs., 2 tabs.

1-Methyl-1H-pyrazolo[3,4-d]pyrimidin-4(5H-one

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Mohamed El Hafi

2018-03-01

Full Text Available The title molecule, C6H6N4O, is essentially planar [dihedral angle between the rings = 0.46 (9°]. The crystal structure consists of sheets of molecules lying parallel to (\\overline{1}11 formed by a combination of N—H...O, C—H...O and C—H...H hydrogen bonds. The sheets are connected through π–π stacking interactions.

1,5-Dimethyl-4-(1-methyl-3-oxo-3-phenylprop-1-enylamino-2-phenyl-1H-pyrazol-3(2H-one

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Hualing Zhu

2011-07-01

Full Text Available In the title compound, C21H21N3O2, an intramolecular N—H...O interaction generates an S(6 ring, which stablizes the enamine–keto tautomer. The S(6 ring makes dihedral angles of 33.07 (7, 56.50 (8 and 38.59 (8°, respectively, with the benzoylacetone benzene ring and the antipyrine pyrazole and benzene rings.

2-(4-Bromophenyl-2-oxoethyl 2-methylbenzoate

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Hoong-Kun Fun

2011-11-01

Full Text Available In the title compound, C16H13BrO3, the dihedral angle formed between the bromo- and methyl-substituted benzene rings is 66.66 (8°. In the crystal, molecules are linked by intermolecular C—H...O hydrogen bonds, forming a two-dimensional network parallel to the ac plane. The crystal packing is further consolidated by C—H...π interactions.

1,1′-Bicyclohexyl-1,1′-diyl 2,2′-bipyridine-3,3′-dicarboxylate

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Hoong-Kun Fun

2012-06-01

Full Text Available The title compound, C24H26N2O4, lies about a crystallographic twofold rotation axis. The cyclohexane rings adopts a chair conformation. The two pyridine rings form a dihedral angle of 41.02 (4°. In the crystal, molecules are linked via C—H...O and C—H...N hydrogen bonds into a layer parallel to the bc plane.

3-Ethyl-4-[(E-(4-fluorobenzylideneamino]-1H-1,2,4-triazole-5(4H-thione

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Alphonsus D'souza

2012-05-01

Full Text Available In the title compound, C11H11FN4S, the dihedral angle between the 1,2,4-triazole ring and the benzene ring is 25.04 (12° and an intramoleuclar C—H...S interaction leads to an S(6 ring. In the crystal, inversion dimers linked by pairs of N—H...S hydrogen bonds generate R22(8 loops.

cis-Tetrachloridobis(1H-imidazole-κN3platinum(IV

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Vadim Yu. Kukushkin

2012-05-01

Full Text Available In the title complex, cis-[PtCl4(C3H4N22], the PtIV ion lies on a twofold rotation axis and is coordinated in a slightly distorted octahedral geometry. The dihedral angle between the imidazole rings is 69.9 (2°. In the crystal, molecules are linked by N—H...Cl hydrogen bonds, forming a three-dimensional network.

Laser peripheral iridoplasty for angle-closure.

Science.gov (United States)

Ng, Wai Siene; Ang, Ghee Soon; Azuara-Blanco, Augusto

2012-02-15

Angle-closure glaucoma is a leading cause of irreversible blindness in the world. Treatment is aimed at opening the anterior chamber angle and lowering the IOP with medical and/or surgical treatment (e.g. trabeculectomy, lens extraction). Laser iridotomy works by eliminating pupillary block and widens the anterior chamber angle in the majority of patients. When laser iridotomy fails to open the anterior chamber angle, laser iridoplasty may be recommended as one of the options in current standard treatment for angle-closure. Laser peripheral iridoplasty works by shrinking and pulling the peripheral iris tissue away from the trabecular meshwork. Laser peripheral iridoplasty can be used for crisis of acute angle-closure and also in non-acute situations.   To assess the effectiveness of laser peripheral iridoplasty in the treatment of narrow angles (i.e. primary angle-closure suspect), primary angle-closure (PAC) or primary angle-closure glaucoma (PACG) in non-acute situations when compared with any other intervention. In this review, angle-closure will refer to patients with narrow angles (PACs), PAC and PACG. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 12), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 5 January 2012. We included only randomised controlled trials (RCTs) in this review. Patients with narrow angles, PAC or PACG were eligible. We excluded studies that included only patients with acute presentations

N-(2,5-Dimethylphenyl-4-methylbenzenesulfonamide

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B. Thimme Gowda

2010-01-01

Full Text Available In the crystal structure of the title compound, C15H17NO2S, the conformation of the N—C bond in the C—SO2—NH—C segment has gauche torsions with respect to the S=O bonds. The molecule is bent at the S atom with a C—SO2—NH—C torsion angle of −61.0 (2°. The dihedral angle between the two aromatic rings is 49.4 (1°. The crystal structure features inversion-related dimers linked by pairs of N—H...O hydrogen bonds.

Biological and spectral studies of O-Tolyl Biguanide: Experimental and theoretical approach

Science.gov (United States)

Beaula, T. Joselin; Muthuraja, P.; Sethuram, M.; Dhandapani, M.; Rastogi, V. K.; Jothy, V. Bena

2017-01-01

Antibiotic and antimicrobial compound O-Tolyl Biguanide (OTB) structure was calculated at the B3LYP using 6-311++G(d,p) basis set level of theory. Optimized geometric bond lengths, bond angles and dihedral angles of the molecule were calculated and analyzed. FT-IR and FT-Raman spectra of OTB were recorded and vibrational assignments of the observed fundamental bands had been proposed on the basis of peak positions and relative intensities. Molecular geometry, vibrational spectra, covalent bond orders and atomic charges of OTB had been used to investigate the effects of charge delocalization leading to Y-aromaticity.

Quantitative evaluation of orbital hybridization in carbon nanotubes under radial deformation using π-orbital axis vector

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Masato Ohnishi

2015-04-01

Full Text Available When a radial strain is applied to a carbon nanotube (CNT, the increase in local curvature induces orbital hybridization. The effect of the curvature-induced orbital hybridization on the electronic properties of CNTs, however, has not been evaluated quantitatively. In this study, the strength of orbital hybridization in CNTs under homogeneous radial strain was evaluated quantitatively. Our analyses revealed the detailed procedure of the change in electronic structure of CNTs. In addition, the dihedral angle, the angle between π-orbital axis vectors of adjacent atoms, was found to effectively predict the strength of local orbital hybridization in deformed CNTs.

6-(4-Bromophenyl-2-(4-fluorobenzylimidazo[2,1-b][1,3,4]thiadiazole

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Afshan Banu

2011-04-01

Full Text Available In the title compound, C17H11BrFN3S, the imidazothiadiazole and bromophenyl rings are individually almost planar, with maximum deviations of 0.0215 (4 and 0.0044 (4 Å, respectively, and are inclined at an angle of 27.34 (3° with respect to each other. The dihedral angle between the mean planes of the fluorobenzyl and imidazothiadiazole rings is 79.54 (3°. The crystal structure is stabilized by intermolecular C—H...N interactions resulting in chains of molecules along the b axis.

(1S,1′S,2′R,4a'S,9a'S,9b'R-1′-Acetyloxy-2,4′-dioxo-2′,4′,4a',7′,8′,9′,9a',9b'-octahydro-1′H,2H-spiro[acenaphthylene-1,5′-pyrano[4,3-a]pyrrolizin]-2′-ylmethyl acetate

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S. Santhiya

2013-11-01

Full Text Available In the title compound C26H25NO7, the mean plane through the lactone-substituted ring of the pyrrolizidine moiety forms dihedral angles of 78.46 (6 and 58.28 (8° with the acenaphthylene moiety and the sugar based-lactone ring, respectively. The sum of the angles at the the N atom of the pyrrolizidine ring (335.0° is in accordance with sp3 hybridization. Some atoms of the acetate group are disordered and were refined using a split model [occupancy ratio 0.673 (10:0.327 (10].

Angle parameter changes of phacoemulsification and combined phacotrabeculectomy for acute primary angle closure

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Shi-Wei Li

2015-08-01

Full Text Available AIM: To evaluate the difference in angle parameters and clinical outcome following phacoemulsification and combined phacotrabeculectomy in patients with acute primary angle closure (APAC using ultrasound biomicroscopy (UBM.METHODS: Patients (n=23, 31 eyes were randomized to receive phacoemulsification or combined phacotrabeculectomy (n=24, 31 eyes. Best-corrected visual acuity (BCVA, intraocular pressure (IOP, the main complications following surgery, and indentation gonioscopy and angle parameters measured using UBM were documented preoperatively and postoperatively.RESULTS:The improvement in BCVA in the phacoemulsification group was significantly greater than in the combined group (P<0.05. IOP in the phacoemulsification group was slightly higher than in the combined group following 1wk of follow-up (P<0.05, whereas there was no significant difference between the two groups at the latter follow-up (P>0.05. Phacoemulsification alone resulted in a slight increase in the trabecular ciliary processes distance compared with the combined surgery (P<0.05, whereas the other angle parameters showed no significant difference between the groups. Complications in combined group were greater than phacoemulsification only group.CONCLUSION:Both surgeries effectively opened the drainage angle and deepened the anterior chamber, and IOP was well controlled postoperatively. However, phacoemulsification showed better efficacy in improving visual function and showed reduced complications following surgery.

ESTIMATING LONG GRB JET OPENING ANGLES AND REST-FRAME ENERGETICS

Energy Technology Data Exchange (ETDEWEB)

Goldstein, Adam [Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Connaughton, Valerie [Science and Technology Institute, Universities Space Research Association, Huntsville, AL 35805 (United States); Briggs, Michael S.; Burns, Eric, E-mail: adam.m.goldstein@nasa.gov [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Drive, Huntsville, AL 35899 (United States)

2016-02-10

We present a method to estimate the jet opening angles of long duration gamma-ray bursts (GRBs) using the prompt gamma-ray energetics and an inversion of the Ghirlanda relation, which is a correlation between the time-integrated peak energy of the GRB prompt spectrum and the collimation-corrected energy in gamma-rays. The derived jet opening angles using this method and detailed assumptions match well with the corresponding inferred jet opening angles obtained when a break in the afterglow is observed. Furthermore, using a model of the predicted long GRB redshift probability distribution observable by the Fermi Gamma-ray Burst Monitor (GBM), we estimate the probability distributions for the jet opening angle and rest-frame energetics for a large sample of GBM GRBs for which the redshifts have not been observed. Previous studies have only used a handful of GRBs to estimate these properties due to the paucity of observed afterglow jet breaks, spectroscopic redshifts, and comprehensive prompt gamma-ray observations, and we potentially expand the number of GRBs that can be used in this analysis by more than an order of magnitude. In this analysis, we also present an inferred distribution of jet breaks which indicates that a large fraction of jet breaks are not observable with current instrumentation and observing strategies. We present simple parameterizations for the jet angle, energetics, and jet break distributions so that they may be used in future studies.

Uncertainty in T1 mapping using the variable flip angle method with two flip angles

International Nuclear Information System (INIS)

Schabel, Matthias C; Morrell, Glen R

2009-01-01

Propagation of errors, in conjunction with the theoretical signal equation for spoiled gradient echo pulse sequences, is used to derive a theoretical expression for uncertainty in quantitative variable flip angle T 1 mapping using two flip angles. This expression is then minimized to derive a rigorous expression for optimal flip angles that elucidates a commonly used empirical result. The theoretical expressions for uncertainty and optimal flip angles are combined to derive a lower bound on the achievable uncertainty for a given set of pulse sequence parameters and signal-to-noise ratio (SNR). These results provide a means of quantitatively determining the effect of changing acquisition parameters on T 1 uncertainty. (note)

Class of exactly solvable scattering potentials in two dimensions, entangled-state pair generation, and a grazing-angle resonance effect

Science.gov (United States)

Loran, Farhang; Mostafazadeh, Ali

2017-12-01

We provide an exact solution of the scattering problem for the potentials of the form v (x ,y ) =χa(x ) [v0(x ) +v1(x ) ei α y] , where χa(x ) :=1 for x ∈[0 ,a ] , χa(x ) :=0 for x ∉[0 ,a ] , vj(x ) are real or complex-valued functions, χa(x ) v0(x ) is an exactly solvable scattering potential in one dimension, and α is a positive real parameter. If α exceeds the wave number k of the incident wave, the scattered wave does not depend on the choice of v1(x ) . In particular, v (x ,y ) is invisible if v0(x ) =0 and k α and v1(x ) ≠0 , the scattered wave consists of a finite number of coherent plane-wave pairs ψn± with wave vector: kn=(±√{k2-[nα ] 2 },n α ) , where n =0 ,1 ,2 ,...generating quantum states with a quantized component of momentum and pairs of states with an entangled momentum. We examine a realization of these potentials in terms of certain optical slabs. If k =N α for some positive integer N , ψN± coalesce and their amplitude diverge. If k exceeds N α slightly, ψN± have a much larger amplitude than ψn± with n angle with the faces of the slab.

Exact quantum cross sections for a three dimensional angle dependent model for three body reactions.

Science.gov (United States)

Baer, M.; Kouri, D. J.

1971-01-01

Exact quantum mechanical reactive cross sections are reported for a three dimensional angle dependent model surface. The surface simulates an atom-heteronuclear diatom system A + BC leading to AB + C where atom B is much heavier than A or C. The molecules BC and AB are taken to be rotating vibrators which can dissociate. Results for two angle dependent potentials are given.

Calculation of atom ranges in solids for quasi-small-angle scattering

International Nuclear Information System (INIS)

Pustovit, A.N.

2004-01-01

A formula for quasi-small-angle scattering of atomic particle and power law interaction potential have been used for the calculation of the differential cross-section, elastic stopping cross-section and a mean projected range in a solid. It is found that the limit energy transfer in the collisions depends on the screening of the power law interaction potentials. The calculated mean ranges in matter are compared with experimental data [ru

Survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces

International Nuclear Information System (INIS)

Neskovic, N.; Ciric, D.; Perovic, B.

1982-01-01

The survival probability in small angle scattering of low energy alkali ions from alkali covered metal surfaces is considered. The model is based on the momentum approximation. The projectiles are K + ions and the target is the (001)Ni+K surface. The incident energy is 100 eV and the incident angle 5 0 . The interaction potential of the projectile and the target consists of the Born-Mayer, the dipole and the image charge potentials. The transition probability function corresponds to the resonant electron transition to the 4s projectile energy level. (orig.)

Implant Angle Monitor System of MC3-II

International Nuclear Information System (INIS)

Sato, Fumiaki; Sano, Makoto; Nakaoka, Hiroaki; Fujii, Yoshito; Kudo, Tetuya; Nakanishi, Makoto; Koike, Masazumi; Fujino, Yasushi

2008-01-01

Precise implant angle control is required for the latest generation of ion implanters to meet further shrink semiconductor device requirements. Especially, the highest angle accuracy is required for Halo implant process of Logic devices. The Halo implant angle affects the device performance, because slight differences of beam divergence change the overlap profile towards the extension. Additionally, twist angle accuracy is demanded in case of channeling angle implant. Therefore monitoring beam angles and wafer twist angles is important. A new monitoring system for the MC3-II, SEN Corp.'s single wafer type medium current implanter has been developed. This paper describes the angle control performance and monitoring system of the MC3-II. For the twist angle control, we developed a wafer notch angle monitor. The system monitors the wafer notch image on the platen. And the notch angle variation is calculated by using image processing method. It is also able to adjust the notch angle according to the angle error. For the tilt angle control, we developed a vertical beam profile monitor. The monitor system can detect beam profile of vertical directions with horizontally scanning beam. It also measures beam angles of a tilt direction to a wafer. The system configuration and sample beam data are presented.

UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

Science.gov (United States)

Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

2014-03-07

The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

Experimental study of crossing angle collision

International Nuclear Information System (INIS)

Chen, T.; Rice, D.; Rubin, D.; Sagan, D.; Tigner, M.

1993-01-01

The non-linear coupling due to the beam-beam interaction with crossing angle has been studied. The major effect of a small (∼12mrad) crossing angle is to excite 5Q x ±Q s =integer coupling resonance family on large amplitude particles, which results in bad lifetime. On the CESR, a small crossing angle (∼2.4mr) was created at the IP and a reasonable beam-beam tune-shift was achieved. The decay rate of the beam is measured as a function of horizontal tune with and without crossing angle. The theoretical analysis, simulation and experimental measurements have a good agreement. The resonance strength as a function of crossing angle is also measured

Multi-angle compound imaging

DEFF Research Database (Denmark)

Jespersen, Søren Kragh; Wilhjelm, Jens Erik; Sillesen, Henrik

1998-01-01

This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared to conve......This paper reports on a scanning technique, denoted multi-angle compound imaging (MACI), using spatial compounding. The MACI method also contains elements of frequency compounding, as the transmit frequency is lowered for the highest beam angles in order to reduce grating lobes. Compared...... to conventional B-mode imaging MACI offers better defined tissue boundaries and lower variance of the speckle pattern, resulting in an image with reduced random variations. Design and implementation of a compound imaging system is described, images of rubber tubes and porcine aorta are shown and effects...... on visualization are discussed. The speckle reduction is analyzed numerically and the results are found to be in excellent agreement with existing theory. An investigation of detectability of low-contrast lesions shows significant improvements compared to conventional imaging. Finally, possibilities for improving...

Two consistent calculations of the Weinberg angle

International Nuclear Information System (INIS)

Fairlie, D.B.

1979-01-01

The Weinberg-Salam theory is reformulated as a pure Yang-Mills theory in a six-dimensional space, the Higgs field being interpreted as gauge potentials in the additional dimensions. Viewed in this way, the condition that the Higgs field transforms as a U(1) representation of charge one is equivalent to requiring a value of 30 0 C for the Weinberg angle. A second consistent determination comes from the idea borrowed from monopole theory that the electromagnetic field is in the direction of the Higgs field. (Author)

Dynamic contact angle cycling homogenizes heterogeneous surfaces.

Science.gov (United States)

Belibel, R; Barbaud, C; Mora, L

2016-12-01

In order to reduce restenosis, the necessity to develop the appropriate coating material of metallic stent is a challenge for biomedicine and scientific research over the past decade. Therefore, biodegradable copolymers of poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) were prepared in order to develop a new coating exhibiting different custom groups in its side chain and being able to carry a drug. This material will be in direct contact with cells and blood. It consists of carboxylic acid and hexylic groups used for hydrophilic and hydrophobic character, respectively. The study of this material wettability and dynamic surface properties is of importance due to the influence of the chemistry and the potential motility of these chemical groups on cell adhesion and polymer kinetic hydrolysis. Cassie theory was used for the theoretical correction of contact angles of these chemical heterogeneous surfaces coatings. Dynamic Surface Analysis was used as practical homogenizer of chemical heterogeneous surfaces by cycling during many cycles in water. In this work, we confirmed that, unlike receding contact angle, advancing contact angle is influenced by the difference of only 10% of acidic groups (%A) in side-chain of polymers. It linearly decreases with increasing acidity percentage. Hysteresis (H) is also a sensitive parameter which is discussed in this paper. Finally, we conclude that cycling provides real information, thus avoiding theoretical Cassie correction. H(10)is the most sensible parameter to %A. Copyright © 2016 Elsevier B.V. All rights reserved.

8-[(3-Phenyl-1,2,4-oxadiazol-5-ylmethoxy]quinoline monohydrate

Directory of Open Access Journals (Sweden)

Shu-Yuan Bai

2013-07-01

Full Text Available In the title compound, C18H13N3O2·H2O, the oxadiazole ring forms dihedral angles 7.21 (10 and 21.25 (11° with the quinoline and benzene rings, respectively. The crystal structure features O—H...N hydrogen bonds and is further consolidated by C—H...O hydrogen-bonding interactions involving the water molecule of hydration.

N,N′-Bis(diphenylmethylbenzene-1,4-diamine

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Aeed S. Al-Fahdawi

2014-01-01

Full Text Available The complete molecule of the title compound, C32H28N2, is generated by crystallographic inversion symmetry. The dihedral angles between the central aromatic ring and the pendant adjacent rings are 61.37 (16 and 74.20 (14°. The N—H group does not participate in hydrogen bonds and there are no aromatic π–π stacking interactions in the crystal.

5-(5-Bromo-2-methoxyphenyl-2-fluoropyridine

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Muhammad Adeel

2012-09-01

Full Text Available In the title compound, C12H9BrFNO, the dihedral angle between the aromatic rings is 51.39 (5°; the C atom of the methoxy group is close to being coplanar with its attached ring (r.m.s. deviation = 0.0172 Å] and is oriented away from the pyridine ring. In the crystal, molecules interact by van der Waals forces.

4-(2-Fluoropyridin-5-ylphenol

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Fazal Elahi

2012-07-01

Full Text Available In the title compound, C11H8FNO, the aromatic rings are oriented at a dihedral angle of 31.93 (6°. In the crystal, molecules are linked by O—H...N hydrogen bonds, forming C(9 chains propagating along the c-axis direction. There are aromatic π–π stacking interactions between the pyridine rings [centroid–centroid separation = 3.7238 (16 Å].

(1R,2R-N,N′-Bis(ferrocenylmethyl-1,2-diphenylethane-1,2-diamine

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Yi Guo

2010-08-01

Full Text Available The title compound, [Fe2(C5H52(C26H26N2], was synthesized from a chiral diamine and ferrocenecarboxaldehyde and subsequent reduction with NaBH4. It has two chiral centers which both exhibit an R configuration. Two ferrocene groups are present in the molecular structure, with their cyclopentadienyl ring planes showing an almost perpendicular arrangement [dihedral angle 88.6 (1°].

N-(2,4,6-Trimethylphenylformamide

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David C. Liles

2011-01-01

Full Text Available The title compound, C10H13NO, was obtained as the unexpected, almost exclusive, product in the attempted synthesis of a manganese(I–N-heterocyclic carbene (NHC complex. The dihedral angle between the planes of the formamide moiety and the aryl ring is 68.06 (10°. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming infinite chains along the c axis.

2,2′-[Biphenyl-2,2′-diylbis(oxy]diacetic acid monohydrate

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Kuldip Singh

2008-10-01

Full Text Available In the crystal structure of the title compound, C16H14O6·H2O, the dihedral angle between the benzene rings is 60.8 (3°. Molecules are linked through a bifurcated O—H...O hydrogen bond, forming a zigzag chain along the b axis. The chains are further linked by O—H...O hydrogen bonds mediated by water molecules.

(2R,3aR,4S,7R,7aS,9R,10aR,11S,14R,14aS-rel-3a,4,7,7a,10a,11,14,14a-Octahydro-4,14:7,11-diepoxy-2,9-propanonaphtho[1,2-f:5,6-f′]diisoindole-1,3,8,10-tetrone (9CI: a cyclophane derived from naphtho[1,2-c:5,6-c]difuran

Directory of Open Access Journals (Sweden)

Peter W. Dibble

2008-09-01

Full Text Available The title compound, C25H18N2O6, is a naphthalenophane styled in the manner of Warrener's alicyclic cyclophanes or molecular racks wherein a trimethylene tether is perfectly staggered between the two N atoms such that the central methylene H atoms point toward the naphthalene π-system. The dihedral angle between the mean planes of the two benzene rings is 7.61 (7°.

2-(2-Chlorophenyl-2,3-dihydroquinazolin-4(1H-one

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Ming-Jian Li

2009-09-01

Full Text Available The title compound, C14H11ClN2O, was synthesized by the reaction of 2-chlorobenzaldehyde and 2-aminobenzamide in an ionic liquid. The pyrimidine ring adopts a skew-boat conformation and the two benzene rings make a dihedral angle of 87.1 (1°. In the crystal, N—H...O and C—H...N hydrogen bonding links the molecules along b.

4,5,6,7-Tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenylindane

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Alan J. Lough

2008-02-01

Full Text Available The title compound (OctaInd, C18H12Br8, is a commercial brominated flame retardant (BFR. In the molecule, the five-membered ring has a slight envelope conformation, with a deviation of 0.317 (9 Å for the flap C atom from four essentially planar C atoms. The dihedral angle between the two benzene rings is 74.00 (16 Å.

2-[(2-Chlorobenzylideneamino]-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile

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Abdullah M. Asiri

2011-09-01

Full Text Available In the title compound, C16H13ClN2S, the mean planes fitted through all non-H atoms of the heterocyclic five-membered and the benzene rings are oriented at a dihedral angle of 5.19 (7°. In the crystal, a weak C—H...π interaction occurs, along with weak π–π interactions [cenroid–centroid distance = 3.7698 (11 Å].

cis-Tetra­chloridobis(1H-imidazole-κN 3)platinum(IV)

Science.gov (United States)

Bokach, Nadezhda A.; Kukushkin, Vadim Yu.; Izotova, Yulia A.; Usenko, Natalia I.; Haukka, Matti

2012-01-01

In the title complex, cis-[PtCl4(C3H4N2)2], the PtIV ion lies on a twofold rotation axis and is coordinated in a slightly distorted octa­hedral geometry. The dihedral angle between the imidazole rings is 69.9 (2)°. In the crystal, mol­ecules are linked by N—H⋯Cl hydrogen bonds, forming a three-dimensional network. PMID:22590070

1,2-Bis(2-methoxy-6-formylphenoxyethane

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Hongqi Li

2011-02-01

Full Text Available In the title compound [systematic name: 3,3′-dimethoxy-2,2′-(ethane-1,2-diyldioxydibenzaldehyde], C18H18O6, prepared from 1,2-dibromoethane and ortho-vanillin in the presence of sodium carbonate, the two vanillin units are linked via a CH2–CH2 bridge. The two benzene rings are inclined at a dihedral angle of 41.6 (5°.

2-{[4-(1,3-Benzothiazol-2-ylphenyl](methylamino}acetic acid

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Yong Zhang

2009-11-01

Full Text Available In the title compound, C16H14N2O2S, the dihedral angle between the benzothiazole ring system and benzene ring is 3.11 (2°. In the crystal structure, intermolecular O—H...N hydrogen bonds link molecules into chains along [100] and these chains are, in turn, linked into a three-dimensional network via weak intermolecular C—H...O hydrogen bonds.

N-(4-Fluorophenyl-2,6-dimethyl-1,3-dioxan-4-amine

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Gottimukkala Rambabu

2013-11-01

Full Text Available In the title compound, C12H16FNO2, the dioxane ring adopts a chair conformation with the methyl substituents and the C—N bond in equatorial orientations. Its mean plane subtends a dihedral angle of 40.17 (6° with the benzene ring. In the crystal, weak N—H...F hydrogen bonds link the molecules into C(7 chains propagating in [100].

2-(Dimethylaminoanthraquinone

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Zhuan Fei

2010-12-01

Full Text Available The molecule of the title compound, C16H13NO2, is almost planar, with a maximum deviation of 0.013 (2 Å from the best plane; the dihedral angle between the two aromatic rings is 1.06 (1°. In the crystal, molecules are linked through weak intramolecular C—H...O interactions, forming chains running parallel to [10overline{1}].

2-Ethoxy-4-[2-(3-nitrophenylhydrazonomethyl]phenol

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Jun-Qiang Chen

2009-10-01

Full Text Available The title Schiff base compound, C15H15N3O4, was prepared from a condensation reaction of 3-ethoxy-4-hydroxybenzaldehyde and 3-nitrophenylhydrazine. The molecule is nearly planar; the dihedral angle between the hydroxybenzene ring and the nitrobenzene ring is 6.57 (7°. O—H...O, O—H...N and C—H...O hydrogen bonding helps to stabilize the crystal structure.

(E-4-Bromo-N-(2,3-dimethoxybenzylideneaniline

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Karla Fejfarová

2010-09-01

Full Text Available The title Schiff base compound, C15H14BrNO2, was prepared by the condensation of 2,3-dimethoxybenzaldehyde with 4-bromoaniline. It adopts an E configuration with respect to the C=N bond. The dihedral angle between the two aromatic rings is 56.79 (8°. Weak C—H...O and C—-H...π bonds can be found in the crystal structure.

Resorcinol ninhydrin complex: 1,5,9-trihydroxy-8-oxatetracyclo[7.7.0.02,7.010,15]hexadeca-2,4,6,10(15,11,13-hexaen-16-one

Directory of Open Access Journals (Sweden)

B. Sridhar

2012-05-01

Full Text Available In the title compound, C15H10O5, the cyclopentanone (r.m.s. deviation = 0.049 Å and oxolane (r.m.s. deviation = 0.048 Å rings make a dihedral angle of 67.91 (4°. An intramolecular O—H...O hydrogen bond is observed. In the crystal, molecules associate via O—H...O hydrogen bonds, forming a three-dimensional network.

1-[1-(4-Chloro­phen­yl)ethyl­idene]carbono­hydrazide

Science.gov (United States)

Du, Lingyun; Du, Lei; Wang, Shuhao

2009-01-01

The mol­ecular skeleton of the title mol­ecule, C9H11ClN4O, is essentially planar, the dihedral angle between the ring and the and N/N/C plane being 6.7 (3)°. In the crystal, inter­molecular N—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules into ribbons propagated along [010]. PMID:21577542

RF sheaths for arbitrary B field angles

Science.gov (United States)

D'Ippolito, Daniel; Myra, James

2014-10-01

RF sheaths occur in tokamaks when ICRF waves encounter conducting boundaries and accelerate electrons out of the plasma. Sheath effects reduce the efficiency of ICRF heating, cause RF-specific impurity influxes from the edge plasma, and increase the plasma-facing component damage. The rf sheath potential is sensitive to the angle between the B field and the wall, the ion mobility and the ion magnetization. Here, we obtain a numerical solution of the non-neutral rf sheath and magnetic pre-sheath equations (for arbitrary values of these parameters) and attempt to infer the parametric dependences of the Child-Langmuir law. This extends previous work on the magnetized, immobile ion regime. An important question is how the rf sheath voltage distributes itself between sheath and pre-sheath for various B field angles. This will show how generally previous estimates of the rf sheath voltage and capacitance were reasonable, and to improve the RF sheath BC. Work supported by US DOE grants DE-FC02-05ER54823 and DE-FG02-97ER54392.

A lattice determination of gA and left angle x right angle from overlap fermions

International Nuclear Information System (INIS)

Guertler, M.; Schiller, A.; Streuer, T.; Freie Univ. Berlin

2004-10-01

We present results for the nucleon's axial charge g A and the first moment left angle x right angle of the unpolarized parton distribution function from a simulation of quenched overlap fermions. (orig.)

Does the Angle of the Nail Matter for Pertrochanteric Fracture Reduction? Matching Nail Angle and Native Neck-Shaft Angle.

Science.gov (United States)

Parry, Joshua A; Barrett, Ian; Schoch, Bradley; Yuan, Brandon; Cass, Joseph; Cross, William

2018-04-01

To determine whether fixation of pertrochanteric hip fractures with cephalomedullary nails (CMNs) with a neck-shaft angle (NSA) less than the native NSA affects reduction and lag screw cutout. Retrospective comparative study. Level I trauma center. Patients treated with a CMN for unstable pertrochanteric femur fractures (OTA/AO 31-A2.2 and 31-A2.3) between 2005 and 2014. CMN fixation. NSA reduction and lag screw cutout. Patients fixed with a nail angle less than their native NSA were less likely to have good reductions [17% vs. 60%, 95% confidence interval (CI), -63% to -18%; P = 0.0005], secondary to more varus reductions (41% vs. 10%, 95% CI, 9%-46%; P = 0.01) and more fractures with ≥4 mm of displacement (63% vs. 35%, 95% CI, 3%-49%; P = 0.03). The cutout was not associated with the use of a nail angle less than the native NSA (60% vs. 76%, 95% CI, -56% to 18%; P = 0.5), varus reductions (60% vs. 32%, 95% CI, -13% to 62%; P = 0.3), or poor reductions (20% vs. 17%, 95% CI, -24% to 44%; P = 1.0). The fixation of unstable pertrochanteric hip fractures with a nail angle less than the native NSA was associated with more varus reductions and fracture displacement but did not affect the lag screw cutout. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

An angled nano-tunnel fabricated on poly(methyl methacrylate) by a focused ion beam

International Nuclear Information System (INIS)

Her, Eun Kyu; Chung, Hee-Suk; Oh, Kyu Hwan; Moon, Myoung-Woon

2009-01-01

Angled nano-scale tunnels with high aspect ratio were fabricated on poly(methyl methacrylate) (PMMA) using a focused ion beam (FIB). The fabrication parameters such as ion fluence, incidence angle, and acceleration voltage of the Ga + ion beam were first studied on the PMMA surface to explore the formation of the nano-scale configurations such as nano-holes and cones with diameter in the range of 50-150 nm at an ion beam acceleration voltage of 5-20 kV. It was also found that the PMMA surface exposed to FIB was changed into an amorphous graphitic structure. Angled nano-scale tunnels were fabricated with high aspect ratio of 700-1500 nm in depth and 60 nm in mean diameter at an ion beam acceleration voltage of 5 kV and under a specific ion beam current. The angle of the nano-tunnels was found to follow the incident angle of the ion beam tilted from 0 0 to 85 0 , which has the potential for creating a mold for anisotropic adhesives by mimicking the hairs on a gecko's feet.

Small angle slot divertor concept for long pulse advanced tokamaks

Science.gov (United States)

Guo, H. Y.; Sang, C. F.; Stangeby, P. C.; Lao, L. L.; Taylor, T. S.; Thomas, D. M.

2017-04-01

SOLPS-EIRENE edge code analysis shows that a gas-tight slot divertor geometry with a small-angle (glancing-incidence) target, named the small angle slot (SAS) divertor, can achieve cold, dissipative/detached divertor conditions at relatively low values of plasma density at the outside midplane separatrix. SAS exhibits the following key features: (1) strong enhancement of the buildup of neutral density in a localized region near the plasma strike point on the divertor target; (2) spreading of the cooling front across the divertor target with the slot gradually flaring out from the strike point, thus effectively reducing both heat flux and erosion on the entire divertor target surface. Such a divertor may potentially provide a power and particle handling solution for long pulse advanced tokamaks.

Glymphatic stasis at the site of the lamina cribrosa as a potential mechanism underlying open-angle glaucoma.

Science.gov (United States)

Wostyn, Peter; Killer, Hanspeter Esriel; De Deyn, Peter Paul

2017-07-01

The underlying pathophysiology of primary open-angle glaucoma remains unclear, but the lamina cribrosa seems to be the primary site of injury, and raised intraocular pressure is a major risk factor. In recent years, a decreased intracranial pressure, leading to an abnormally high trans-lamina cribrosa pressure difference, has gained interest as a new risk factor for glaucoma. New research now lends support to the hypothesis that a paravascular transport system is present in the eye analogous to the recently discovered 'glymphatic system' in the brain, which is a functional waste clearance pathway that promotes elimination of interstitial solutes, including β-amyloid, from the brain along paravascular channels. Given that β-amyloid has been reported to increase by chronic elevation of intraocular pressure in glaucomatous animal models and to cause retinal ganglion cell death, the discovery of a paravascular clearance system in the eye may provide powerful new insights into the pathophysiology of primary open-angle glaucoma. In this review, we provide a new conceptual framework for understanding the pathogenesis of primary open-angle glaucoma, present supporting preliminary data from our own post-mortem study and hypothesize that the disease may result from restriction of normal glymphatic flow at the level of the lamina cribrosa owing to a low intracranial pressure and/or a high trans-lamina cribrosa pressure gradient. If confirmed, this viewpoint could offer new perspectives for the development of novel diagnostic and therapeutic strategies for this devastating disorder. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Development of scanning micromirror with discrete steering angles

International Nuclear Information System (INIS)

Wang, Z F; Noell, W; Zickar, M; Rooij, N F de; Lim, S P

2006-01-01

This paper describes the development of a new MEMS-based optical mirror, which can perform optical switching (or scanning) function with discrete reflection angles in an outof- plane configuration. The device is fabricated through the Deep Reactive Ion Etching (DRIE) process on silicon-on-insulator (SOI) wafer, followed by wafer dicing and assembly with two metalised glass dies. The MEMS mirror can be tilted under electrostatic force between the opposite electrodes embedded on SOI and glass structures. The most outstanding feature of this MEMS mirror is the discrete and therefore, reliable tilting angles, which generated by its unique mechanical structural design and electrostatic-driven mechanism. In this paper, the concept of the new scanning mirror is presented, followed by the introduction of device design, mechanical simulation, microfabrication process, assembly solution, and some testing results. The potential applications of this new MEMS mirror include optical scanning, optical sensing (or detection), and optical switching

Action–angle variables, ladder operators and coherent states

International Nuclear Information System (INIS)

Campoamor-Stursberg, R.; Gadella, M.; Kuru, Ş.; Negro, J.

2012-01-01

This Letter is devoted to the building of coherent states from arguments based on classical action–angle variables. First, we show how these classical variables are associated to an algebraic structure in terms of Poisson brackets. In the quantum context these considerations are implemented by ladder type operators and a structure known as spectrum generating algebra. All this allows to generate coherent states and thereby the correspondence of classical–quantum properties by means of the aforementioned underlying structure. This approach is illustrated with the example of the one-dimensional Pöschl–Teller potential system. -- Highlights: ► We study the building of coherent states from classical action–angle variables arguments. ► The classical variables are associated to an algebraic structure in terms of Poisson brackets. ► In the quantum context these considerations are implemented by ladder type operators. ► All this allows to formulate coherent states and the correspondence of classical–quantum properties.

Ten helical twist angles of B-DNA

Energy Technology Data Exchange (ETDEWEB)

Kabsch, W; Sander, C; Trifonov, E N

1982-01-01

On the assumption that the twist angles between adjacent base-pairs in the DNA molecule are additive a linear system of 40 equations was derived from experimental measurements of the total twist angles for different pieces of DNA of known sequences. This system of equations is found to be statistically consistent providing a solution for all ten possible twist angles of B-DNA by a least squares fitting procedure. Four of the calculated twist angles were not known before. The other six twist angles calculated are very close to the experimentally measured ones. The data used were obtained by the electrophoretic band-shift method, crystallography and nuclease digestion of DNA adsorbed to mica or Ca-phosphate surface. The validity of the principle of additivity of the twist angles implies that the angle between any particular two base-pairs is a function of only these base-pairs, independent of nearest neighbors.

Glymphatic stasis at the site of the lamina cribrosa as a potential mechanism underlying open-angle glaucoma

NARCIS (Netherlands)

Wostyn, Peter; Killer, Hanspeter Esriel; De Deyn, Peter Paul

The underlying pathophysiology of primary open-angle glaucoma remains unclear, but the lamina cribrosa seems to be the primary site of injury, and raised intraocular pressure is a major risk factor. In recent years, a decreased intracranial pressure, leading to an abnormally high trans-lamina

The probability distribution of side-chain conformations in [Leu] and [Met]enkephalin determines the potency and selectivity to mu and delta opiate receptors

DEFF Research Database (Denmark)

Nielsen, Bjørn Gilbert; Jensen, Morten Østergaard; Bohr, Henrik

2003-01-01

The structure of enkephalin, a small neuropeptide with five amino acids, has been simulated on computers using molecular dynamics. Such simulations exhibit a few stable conformations, which also have been identified experimentally. The simulations provide the possibility to perform cluster analysis...... in the space defined by potentially pharmacophoric measures such as dihedral angles, side-chain orientation, etc. By analyzing the statistics of the resulting clusters, the probability distribution of the side-chain conformations may be determined. These probabilities allow us to predict the selectivity...... of [Leu]enkephalin and [Met]enkephalin to the known mu- and delta-type opiate receptors to which they bind as agonists. Other plausible consequences of these probability distributions are discussed in relation to the way in which they may influence the dynamics of the synapse....

Synthesis and Structural Characterization of 1-[2-(5-Nitro-1H-indol-2-ylphenyl]methylpyridinium Chloride

Directory of Open Access Journals (Sweden)

John B. Bremner

2011-09-01

Full Text Available In the course of studies on hybrid antibacterials incorporating 2-aryl-5-nitro-1H-indole moieties as potential bacterial NorA efflux pump inhibitors, the compound 1-[2-(5-nitro-1H-indol-2-ylphenyl]methylpyridinium chloride (2 was synthesized and structurally characterized. This pyridinium chloride salt crystallized in the monoclinic space group P21/c with the following unit cell dimensions: a 10.274(3 Å, b 13.101(4 Å, c 13.439(4 Å, b 107.702(7°, V 1723.2(9 Å3, Z (f.u. = 4; R1 = 0.048, and wR2 = 0.13. Of interest in the single crystal X-ray structure is the (intramolecular disposition of the pyridinium plane over the indole heterocyclic residue [interplanar dihedral angle 17.91(4°].

Contact Angle Measurements: an Alternative Approach Towards Understanding the Mechanism of Increased Drug Dissolution from Ethylcellulose Tablets Containing Surfactant and Exploring the Relationship Between Their Contact Angles and Dissolution Behaviors.

Science.gov (United States)

Liu, Tiaotiao; Hao, Jingqiang; Yang, Baixue; Hu, Beibei; Cui, Zhixiang; Li, Sanming

2018-05-01

The addition of surfactant in tablet was a well-defined approach to improve drug dissolution rate. While the selected surfactant played a vital role in improving the wettability of tablet by medium, it was equally important to improve the dissolution rate by permeation effect due to production of pores or the reduced inter-particle adhesion. Furthermore, understanding the mechanism of dissolution rate increased was significant. In this work, contact angle measurement was taken up as an alternative approach for understanding the dissolution rate enhancement for tablet containing surfactant. Ethylcellulose, as a substrate, was used to prepare tablet. Four surfactants, sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), dodecyltrimethylammonium bromide (DTAB), and sodium lauryl sulfonate (SLS), were used. Berberine hydrochloride, metformin hydrochloride, and rutin were selected as model drugs. The contact angle of tablet in the absence and presence of surfactant was measured to explore the mechanism. The dissolution test was investigated to verify the mechanism and to establish a correlation with the contact angle. The result showed that the mechanism was the penetration effect rather than the wetting effect. The dissolution increased with a reduction in the contact angle. DTAB was found to obtain the highest level of dissolution enhancement and the lowest contact angle, while SDS, SDBS, and SLS were found to be the less effective in both dissolution enhancement and contact angle decrease. Therefore, contact angle was a good indicator for dissolution behavior besides exploring the mechanism of increased dissolution, which shows great potential in formula screening.

On the evolution of jet energy and opening angle in strongly coupled plasma

International Nuclear Information System (INIS)

Chesler, Paul M.; Rajagopal, Krishna

2016-01-01

We calculate how the energy and the opening angle of jets in N=4 SYM theory evolve as they propagate through the strongly coupled plasma of that theory. We define the rate of energy loss dE_j_e_t/dx and the jet opening angle in a straightforward fashion directly in the gauge theory before calculating both holographically, in the dual gravitational description. In this way, we rederive the previously known result for dE_j_e_t/dx without the need to introduce a finite slab of plasma. We obtain a striking relationship between the initial opening angle of the jet, which is to say the opening angle that it would have had if it had found itself in vacuum instead of in plasma, and the thermalization distance of the jet. Via this relationship, we show that N=4 SYM jets with any initial energy that have the same initial opening angle and the same trajectory through the plasma experience the same fractional energy loss. We also provide an expansion that describes how the opening angle of the N=4 SYM jets increases slowly as they lose energy, over the fraction of their lifetime when their fractional energy loss is not yet large. We close by looking ahead toward potential qualitative lessons from our results for QCD jets produced in heavy collisions and propagating through quark-gluon plasma.

Nd:Yag laser iridotomy in Shaffer-Etienne grade 1 and 2:angle widening in our case studies

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Sandra Cinzia Carlesimo

2015-08-01

Full Text Available AIM:To obtain widening of a potentially occludable angle, in according to Kanski’s indications, through preventive Nd:Yag laser iridotomy. The observational study was performed by using gonioscopy for the selection and follow-up of 1165 treated eyes and exploiting Shaffer-Etienne gonioscopic classification as a quality/quantity test of the angle recession.METHODS:Between September 2000 and July 2012, 586 patients were selected at the Outpatients’ Ophthalmological Clinic of the Policlinico Umberto I of Rome in order to undergo Nd:Yag laser iridotomy. A Goldmann type contact lens, Q-switched mode, 2-3 defocus, and 7-9 mJ intensity with 2-3 impulse discharges were used for surgery.RESULTS:From as early as the first week, a whole 360° angle widening were evident in the patients, thus showing the success of Nd:Yag laser iridotomy in solving relative pupil block. The angle remained narrow by 270° in 14 eyes only, despite repetitions of further treatment with laser iridotomy in a different part of the iris, twice in 10 eyes and three times in 4 eyes.CONCLUSION:Nd:Yag laser iridotomy revealed itself as being a safe and effective treatment in widening those critical Shaffer-Etienne grade 1 and 2 potentially occludable angles.

Anterior Segment Imaging Predicts Incident Gonioscopic Angle Closure.

Science.gov (United States)

Baskaran, Mani; Iyer, Jayant V; Narayanaswamy, Arun K; He, Yingke; Sakata, Lisandro M; Wu, Renyi; Liu, Dianna; Nongpiur, Monisha E; Friedman, David S; Aung, Tin

2015-12-01

To investigate the incidence of gonioscopic angle closure after 4 years in subjects with gonioscopically open angles but varying degrees of angle closure detected on anterior segment optical coherence tomography (AS OCT; Visante; Carl Zeiss Meditec, Dublin, CA) at baseline. Prospective, observational study. Three hundred forty-two subjects, mostly Chinese, 50 years of age or older, were recruited, of whom 65 were controls with open angles on gonioscopy and AS OCT at baseline, and 277 were cases with baseline open angles on gonioscopy but closed angles (1-4 quadrants) on AS OCT scans. All subjects underwent gonioscopy and AS OCT at baseline (horizontal and vertical single scans) and after 4 years. The examiner performing gonioscopy was masked to the baseline and AS OCT data. Angle closure in a quadrant was defined as nonvisibility of the posterior trabecular meshwork by gonioscopy and visible iridotrabecular contact beyond the scleral spur in AS OCT scans. Gonioscopic angle closure in 2 or 3 quadrants after 4 years. There were no statistically significant differences in age, ethnicity, or gender between cases and controls. None of the control subjects demonstrated gonioscopic angle closure after 4 years. Forty-eight of the 277 subjects (17.3%; 95% confidence interval [CI], 12.8-23; P < 0.0001) with at least 1 quadrant of angle closure on AS OCT at baseline demonstrated gonioscopic angle closure in 2 or more quadrants, whereas 28 subjects (10.1%; 95% CI, 6.7-14.6; P < 0.004) demonstrated gonioscopic angle closure in 3 or more quadrants after 4 years. Individuals with more quadrants of angle closure on baseline AS OCT scans had a greater likelihood of gonioscopic angle closure developing after 4 years (P < 0.0001, chi-square test for trend for both definitions of angle closure). Anterior segment OCT imaging at baseline predicts incident gonioscopic angle closure after 4 years among subjects who have gonioscopically open angles and iridotrabecular contact on AS OCT at

Graded index and randomly oriented core-shell silicon nanowires for broadband and wide angle antireflection

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P. Pignalosa

2011-09-01

Full Text Available Antireflection with broadband and wide angle properties is important for a wide range of applications on photovoltaic cells and display. The SiOx shell layer provides a natural antireflection from air to the Si core absorption layer. In this work, we have demonstrated the random core-shell silicon nanowires with both broadband (from 400nm to 900nm and wide angle (from normal incidence to 60º antireflection characteristics within AM1.5 solar spectrum. The graded index structure from the randomly oriented core-shell (Air/SiOx/Si nanowires may provide a potential avenue to realize a broadband and wide angle antireflection layer.

Influence of Contact Angle, Growth Angle and Melt Surface Tension on Detached Solidification of InSb

Science.gov (United States)

Wang, Yazhen; Regel, Liya L.; Wilcox, William R.

2000-01-01

We extended the previous analysis of detached solidification of InSb based on the moving meniscus model. We found that for steady detached solidification to occur in a sealed ampoule in zero gravity, it is necessary for the growth angle to exceed a critical value, the contact angle for the melt on the ampoule wall to exceed a critical value, and the melt-gas surface tension to be below a critical value. These critical values would depend on the material properties and the growth parameters. For the conditions examined here, the sum of the growth angle and the contact angle must exceed approximately 130, which is significantly less than required if both ends of the ampoule are open.

The resection angle in apical surgery

DEFF Research Database (Denmark)

von Arx, Thomas; Janner, Simone F M; Jensen, Simon S

2016-01-01

OBJECTIVES: The primary objective of the present radiographic study was to analyse the resection angle in apical surgery and its correlation with treatment outcome, type of treated tooth, surgical depth and level of root-end filling. MATERIALS AND METHODS: In the context of a prospective clinical...... study, cone beam computed tomography (CBCT) scans were taken before and 1 year after apical surgery to measure the angle of the resection plane relative to the longitudinal axis of the root. Further, the surgical depth (distance from the buccal cortex to the most lingual/palatal point of the resection...... or with the retrofilling length. CONCLUSIONS: Statistically significant differences were observed comparing resection angles of different tooth groups. However, the angle had no significant effect on treatment outcome. CLINICAL RELEVANCE: Contrary to common belief, the resection angle in maxillary anterior teeth...

Modified Angle's Classification for Primary Dentition.

Science.gov (United States)

Chandranee, Kaushik Narendra; Chandranee, Narendra Jayantilal; Nagpal, Devendra; Lamba, Gagandeep; Choudhari, Purva; Hotwani, Kavita

2017-01-01

This study aims to propose a modification of Angle's classification for primary dentition and to assess its applicability in children from Central India, Nagpur. Modification in Angle's classification has been proposed for application in primary dentition. Small roman numbers i/ii/iii are used for primary dentition notation to represent Angle's Class I/II/III molar relationships as in permanent dentition, respectively. To assess applicability of modified Angle's classification a cross-sectional preschool 2000 children population from central India; 3-6 years of age residing in Nagpur metropolitan city of Maharashtra state were selected randomly as per the inclusion and exclusion criteria. Majority 93.35% children were found to have bilateral Class i followed by 2.5% bilateral Class ii and 0.2% bilateral half cusp Class iii molar relationships as per the modified Angle's classification for primary dentition. About 3.75% children had various combinations of Class ii relationships and 0.2% children were having Class iii subdivision relationship. Modification of Angle's classification for application in primary dentition has been proposed. A cross-sectional investigation using new classification revealed various 6.25% Class ii and 0.4% Class iii molar relationships cases in preschool children population in a metropolitan city of Nagpur. Application of the modified Angle's classification to other population groups is warranted to validate its routine application in clinical pediatric dentistry.

Based on graphene tunable dual-band terahertz metamaterial absorber with wide-angle

Science.gov (United States)

Huang, Mulin; Cheng, Yongzhi; Cheng, Zhengze; Chen, Haoran; Mao, Xuesong; Gong, Rongzhou

2018-05-01

We present a wide-angle tunable dual-band terahertz (THz) metamaterial absorber (MMA) based on square graphene patch (SGP). This MMA is a simple periodic array, consisting of a dielectric substrate sandwiched with the SGP and a continuous metallic film. The designed MMA can achieve dual-band absorption by exciting fundamental and second higher-order resonance modes on SGP. The numerical simulations indicate that the absorption spectrum of the designed MMA is tuned from 0.85 THz to 1.01 THz, and from 2.84 THz to 3.37 THz when the chemical potential of the SGP is increasing from 0.4eV to 0.8eV. Moreover, it operates well in a wide-angle of the incident waves. The presented THz MMA based on the SGP could find some potential applications in optoelectronic related devices, such as sensor, emitter and wavelength selective radiators.

The potential influence of subduction zone polarity on overriding plate deformation, trench migration and slab dip angle

NARCIS (Netherlands)

Schellart, W. P.

2007-01-01

A geodynamic model exists, the westward lithospheric drift model, in which the variety of overriding plate deformation, trench migration and slab dip angles is explained by the polarity of subduction zones. The model predicts overriding plate extension, a fixed trench and a steep slab dip for

Crystal structure of [1,1':3',1''-ter-phenyl]-2',3,3''-tri-carb-oxy-lic acid.

Science.gov (United States)

Decato, Daniel A; Berryman, Orion B

2015-09-01

The asymmetric unit of the title compound, C21H14O6, com-prises two symmetrically independent mol-ecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carb-oxy-lic acid groups rotated by 15.8 (1) and 17.5 (1)° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being inter-connected by hydrogen bonds involving the remaining carb-oxy-lic acid groups. The plane of the central carb-oxy-lic acid group forms dihedral angles of 62.5 (1) and 63.0 (1)° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it inter-connects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The 'distal' carb-oxy-lic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1) and 7.1 (1)°. These groups also form intra- and inter-layer hydrogen bonds, but with 'reversed' functionality, as compared with the central carb-oxy-lic acid groups.

Crystal structure of [1,1′:3′,1′′-terphenyl]-2′,3,3′′-tricarboxylic acid

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Daniel A. Decato

2015-09-01

Full Text Available The asymmetric unit of the title compound, C21H14O6, comprises two symmetrically independent molecules that form a locally centrosymmetric hydrogen-bonded dimer, with the planes of the corresponding carboxylic acid groups rotated by 15.8 (1 and 17.5 (1° relative to those of the adjacent benzene rings. The crystal as a whole, however, exhibits a noncentrosymmetric packing, described by the polar space group Pca21. The dimers form layers along the ab plane, being interconnected by hydrogen bonds involving the remaining carboxylic acid groups. The plane of the central carboxylic acid group forms dihedral angles of 62.5 (1 and 63.0 (1° with those of the adjacent benzene rings and functions as a hydrogen-bond donor and acceptor. As a donor, it interconnects adjacent layers, while as an acceptor it stabilizes the packing within the layers. The `distal' carboxylic acid groups are nearly coplanar with the planes of the adjacent benzene rings, forming dihedral angles of 1.8 (1 and 7.1 (1°. These groups also form intra- and inter-layer hydrogen bonds, but with `reversed' functionality, as compared with the central carboxylic acid groups.

Crystal structures of 4-meth-oxy-N-(4-methyl-phenyl)benzene-sulfonamide and N-(4-fluoro-phenyl)-4-meth-oxy-benzene-sulfonamide.

Science.gov (United States)

Rodrigues, Vinola Z; Preema, C P; Naveen, S; Lokanath, N K; Suchetan, P A

2015-11-01

Crystal structures of two N-(ar-yl)aryl-sulfonamides, namely, 4-meth-oxy-N-(4-methyl-phen-yl)benzene-sulfonamide, C14H15NO3S, (I), and N-(4-fluoro-phen-yl)-4-meth-oxy-benzene-sulfonamide, C13H12FNO3S, (II), were determined and analyzed. In (I), the benzene-sulfonamide ring is disordered over two orientations, in a 0.516 (7):0.484 (7) ratio, which are inclined to each other at 28.0 (1)°. In (I), the major component of the sulfonyl benzene ring and the aniline ring form a dihedral angle of 63.36 (19)°, while in (II), the planes of the two benzene rings form a dihedral angle of 44.26 (13)°. In the crystal structure of (I), N-H⋯O hydrogen bonds form infinite C(4) chains extended in [010], and inter-molecular C-H⋯πar-yl inter-actions link these chains into layers parallel to the ab plane. The crystal structure of (II) features N-H⋯O hydrogen bonds forming infinite one dimensional C(4) chains along [001]. Further, a pair of C-H⋯O inter-molecular inter-actions consolidate the crystal packing of (II) into a three-dimensional supra-molecular architecture.

Contact- and distance-based principal component analysis of protein dynamics

Energy Technology Data Exchange (ETDEWEB)

Ernst, Matthias; Sittel, Florian; Stock, Gerhard, E-mail: stock@physik.uni-freiburg.de [Biomolecular Dynamics, Institute of Physics, Albert Ludwigs University, 79104 Freiburg (Germany)

2015-12-28

To interpret molecular dynamics simulations of complex systems, systematic dimensionality reduction methods such as principal component analysis (PCA) represent a well-established and popular approach. Apart from Cartesian coordinates, internal coordinates, e.g., backbone dihedral angles or various kinds of distances, may be used as input data in a PCA. Adopting two well-known model problems, folding of villin headpiece and the functional dynamics of BPTI, a systematic study of PCA using distance-based measures is presented which employs distances between C{sub α}-atoms as well as distances between inter-residue contacts including side chains. While this approach seems prohibitive for larger systems due to the quadratic scaling of the number of distances with the size of the molecule, it is shown that it is sufficient (and sometimes even better) to include only relatively few selected distances in the analysis. The quality of the PCA is assessed by considering the resolution of the resulting free energy landscape (to identify metastable conformational states and barriers) and the decay behavior of the corresponding autocorrelation functions (to test the time scale separation of the PCA). By comparing results obtained with distance-based, dihedral angle, and Cartesian coordinates, the study shows that the choice of input variables may drastically influence the outcome of a PCA.

2-(5,6-Diphenyl-1,2,4-triazin-3-ylaniline

Directory of Open Access Journals (Sweden)

Mariusz Mojzych

2012-12-01

Full Text Available The title compound, C21H16N4, obtained under standard Suzuki cross-coupling conditions, is a model compound in the synthesis and biological activity evaluation of new aza-analogues of sildenafil containing a pyrazolo[4,3-e][1,2,4]triazine system. An N—H...N intramolecular hydrogen bond involving the aminobenzene system and the 1,2,4-triazine moiety helps to establish a near coplanar orientation of the rings with a dihedral angle of 12.04 (4°, which is believed to be necessary for the biological activity of sildenafil analogues. The 1,2,4-triazine ring is slightly distorted from planarity [r.m.s deviation = 0.0299 (11 Å] and forms dihedral angles of 58.60 (4 and 36.35 (3° with the pendant phenyl rings. The crystal packing features bifurcated N—H...(N,N hydrogen bonds linking screw-axis-related molecules into chains parallel to the [010] direction< and π–π interactions, with a centroid–centroid separation of 3.8722 (7 Å and a slippage of 1.412 (3 Å. The crystal studied was a nonmerohedral twin with a ratio of 0.707 (2:0293 (2.

Crystal structure of trans-diaquabis(4-cyanobenzoato-κObis(N,N-diethylnicotinamide-κNcadmium

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Nurcan Akduran

2016-12-01

Full Text Available The mononuclear title cadmium complex, [Cd(C10H14N2O2(C8H4NO22(H2O2], is centrosymmetric and contains two water molecules, two 4-cyanobenzoate (CB ligands and two diethylnicotinamide (DENA ligands. All the ligands are coordinated to the CdII atom in a monodentate mode. The four nearest O atoms around the CdII atom form a slightly distorted square-planar arrangement, with the distorted octahedral coordination sphere being completed by the two pyridine N atoms of the DENA ligands at distances of 2.3336 (13 Å. The dihedral angle between the carboxylate group and the adjacent benzene ring is 8.75 (16°, while the benzene and pyridine rings are oriented at a dihedral angle of 57.83 (5°. The water molecules exhibit both intramolecular [to the non-coordinating carboxylate O atom, enclosing an S(6 hydrogen-bonding motif, where O...O = 2.670 (2 Å] and intermolecular [to the amide carbonyl O atom, enclosing an R22(16 ring motif, where O...O = 2.781 (2 Å] O—H...O hydrogen bonds. The latter lead to the formation of supramolecular chains propagating along [110].

2-Propoxybenzamide

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Yosef Al Jasem

2012-09-01

Full Text Available In the title molecule, C10H13NO2, the amide –NH2 group is oriented toward the propoxy substituent and an intramolecular N—H...O hydrogen bond is formed between the N—H group and the propoxy O atom. The benzene ring forms dihedral angles of 12.41 (2 and 3.26 (2° with the amide and propoxy group mean planes, respectively. In the crystal, N—H...O hydrogen bonds order pairs of molecules with their molecular planes parallel, but at an offset of 0.73 (2 Å to each other. These pairs are ordered into two types of symmetry-related columns extended along the a axis with the mean plane of a pair in one column approximately parallel to (-122 and in the other to (-1-22. The two planes form dihedral angle of 84.40 (1°. Overall, in a three-dimensional network, the hydrogen-bonded pairs of molecules are either located in (-1-22 or (-122 layers. In one layer, each pair is involved in four C—H...O contacts, twice as a donor and twice as an acceptor. Additionally, there is a short C—H...C contact between a benzene C—H group and the amide π-system.

Nucleation of small angle boundaries

CSIR Research Space (South Africa)

Nabarro, FRN

1996-12-01

Full Text Available The internal stresses induced by the strain gradients in an array of lattice cells delineated by low-angle dislocation boundaries are partially relieved by the creation of new low-angle boundaries. This is shown to be a first-order transition...

The relationship between bioelectrical impedance phase angle and subjective global assessment in advanced colorectal cancer

Directory of Open Access Journals (Sweden)

Grutsch James F

2008-06-01

Full Text Available Abstract Background Bioelectrical Impedance (BIA derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. Methods We evaluated a case series of 73 stages III and IV colorectal cancer patients. Patients were classified as either well-nourished or malnourished using the SGA. BIA was conducted on all patients and phase angle was calculated. The correlation between phase angle and SGA was studied using Spearman correlation coefficient. Receiver Operating Characteristic curves were estimated using the non-parametric method to determine the optimal cut-off levels of phase angle. Results Well-nourished patients had a statistically significantly higher (p = 0.005 median phase angle score (6.12 as compared to those who were malnourished (5.18. The Spearman rank correlation coefficient between phase angle and SGA was found to be 0.33 (p = 0.004, suggesting better nutritional status with higher phase angle scores. A phase angle cut-off of 5.2 was 51.7% sensitive and 79.5% specific whereas a cut-off of 6.0 was 82.8% sensitive and 54.5% specific in detecting malnutrition. Interestingly, a phase angle cut-off of 5.9 demonstrated high diagnostic accuracy in males who had failed primary treatment for advanced colorectal cancer. Conclusion Our study suggests that bioimpedance phase angle is a potential nutritional indicator in advanced colorectal cancer. Further research is needed to elucidate the optimal cut-off levels of phase angle that can be incorporated into the oncology clinic for better nutritional evaluation and management.

Hong's grading for evaluating anterior chamber angle width.

Science.gov (United States)

Kim, Seok Hwan; Kang, Ja Heon; Park, Ki Ho; Hong, Chul

2012-11-01

To compare Hong's grading method with anterior segment optical coherence tomography (AS-OCT), gonioscopy, and the dark-room prone-position test (DRPT) for evaluating anterior chamber width. The anterior chamber angle was graded using Hong's grading method, and Hong's angle width was calculated from the arctangent of Hong's grades. The correlation between Hong's angle width and AS-OCT parameters was analyzed. The area under the receiver operating characteristic curve (AUC) for Hong's grading method when discriminating between narrow and open angles as determined by gonioscopy was calculated. Correlation analysis was performed between Hong's angle width and intraocular pressure (IOP) changes determined by DRPT. A total of 60 subjects were enrolled. Of these subjects, 53.5 % had a narrow angle. Hong's angle width correlated significantly with the AS-OCT parameters (r = 0.562-0.719, P < 0.01). A Bland-Altman plot showed relatively good agreement between Hong's angle width and the angle width obtained by AS-OCT. The ability of Hong's grading method to discriminate between open and narrow angles was good (AUC = 0.868, 95 % CI 0.756-0.942). A significant linear correlation was found between Hong's angle width and IOP change determined by DRPT (r = -0.761, P < 0.01). Hong's grading method is useful for detecting narrow angles. Hong's grading correlated well with AS-OCT parameters and DRPT.

Contact angle hysteresis on superhydrophobic stripes.

Science.gov (United States)

Dubov, Alexander L; Mourran, Ahmed; Möller, Martin; Vinogradova, Olga I

2014-08-21

We study experimentally and discuss quantitatively the contact angle hysteresis on striped superhydrophobic surfaces as a function of a solid fraction, ϕS. It is shown that the receding regime is determined by a longitudinal sliding motion of the deformed contact line. Despite an anisotropy of the texture the receding contact angle remains isotropic, i.e., is practically the same in the longitudinal and transverse directions. The cosine of the receding angle grows nonlinearly with ϕS. To interpret this we develop a theoretical model, which shows that the value of the receding angle depends both on weak defects at smooth solid areas and on the strong defects due to the elastic energy of the deformed contact line, which scales as ϕS(2)lnϕS. The advancing contact angle was found to be anisotropic, except in a dilute regime, and its value is shown to be determined by the rolling motion of the drop. The cosine of the longitudinal advancing angle depends linearly on ϕS, but a satisfactory fit to the data can only be provided if we generalize the Cassie equation to account for weak defects. The cosine of the transverse advancing angle is much smaller and is maximized at ϕS ≃ 0.5. An explanation of its value can be obtained if we invoke an additional energy due to strong defects in this direction, which is shown to be caused by the adhesion of the drop on solid sectors and is proportional to ϕS(2). Finally, the contact angle hysteresis is found to be quite large and generally anisotropic, but it becomes isotropic when ϕS ≤ 0.2.

5-Bromo-4-(3,4-dimethoxyphenylthiazol-2-amine

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Hazem A. Ghabbour

2012-06-01

Full Text Available In the title compound, C11H11BrN2O2S, the thiazole ring makes a dihedral angle of 53.16 (11° with the adjacent benzene ring. The two methoxy groups are slightly twisted from the attached benzene ring with C—O—C—C torsion angles of −9.2 (3 and −5.5 (3°. In the crystal, molecules are linked by a pair of N—H...N hydrogen bonds into an inversion dimer with an R22(8 ring motif. The dimers are further connected by N—H...O hydrogen bonds into a tape along [-110].

Dichlorido{2-[(3,4-dimethylphenyliminomethyl]pyridine-κ2N,N′}copper(II

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Mehdi Khalaj

2011-11-01

Full Text Available In the title complex, [CuCl2(C14H14N2], the CuII atom exhibits a very distorted tetrahedral coordination geometry involving two chloride ions and two N-atom donors from the Schiff base ligand. The range for the six bond angles about the Cu2+ cation is 81.49 (11–145.95 (9°. The chelate ring including the CuII atom is approximately planar, with a maximum deviation of 0.039 (4 Å for one of the C atoms; this plane forms a dihedral angle of 46.69 (9° with the CuCl2 plane.

(2E-3-(4-Chlorophenyl-1-(4-hydroxyphenylprop-2-en-1-one

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Jerry P. Jasinski

2011-04-01

Full Text Available In the title compound, C15H11ClO2, the dihedral angle between the mean planes of the chlorobenzene and hydroxybenzene rings is 6.5 (6°. The mean plane of the prop-2-en-1-one group makes an angle of 18.0 (1° with the hydroxyphenyl ring and 11.5 (1° with the chlorophenyl ring. The crystal packing is stabilized by intermolecular O—H...O hydrogen bonds, weak C—H...O, C—H...π and π–π stacking interactions [centroid–centroid distances = 3.7771 (7 and 3.6917 (7 Å].

Comparison of axial lengths in occludable angle and angle-closure glaucoma-The Bhaktapur Glaucoma Study

NARCIS (Netherlands)

Thapa, S.S.; Paudyal, I.; Khanal, S.; Paudel, N.; van Rens, G.H.M.B.

2011-01-01

Purpose. To compare the anterior chamber depth (ACD) and axial length of eyes in a population-based sample among normal, occludable angle, and primary angle-closure glaucoma (PACG) groups. Methods. Totally, 3979 subjects from a population-based glaucoma prevalence study underwent complete ocular

Low Voltage Electrowetting on Ferroelectric PVDF-HFP Insulator with Highly Tunable Contact Angle Range.

Science.gov (United States)

Sawane, Yogesh B; Ogale, Satishchandra B; Banpurkar, Arun G

2016-09-14

We demonstrate a consistent electrowetting response on ferroelectric poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) insulator covered with a thin Teflon AF layer. This bilayer exhibits a factor of 3 enhancement in the contact angle modulation compared to that of conventional single-layered Teflon AF dielectric. On the basis of the proposed model the enhancement is attributed to the high value of effective dielectric constant (εeff ≈ 6) of the bilayer. Furthermore, the bilayer dielectric exhibits a hysteresis-free contact angle modulation over many AC voltage cycles. But the contact angle modulation for DC voltage shows a hysteresis because of the field-induced residual polarization in the ferroelectric layer. Finally, we show that a thin bilayer exhibits contact angle modulation of Δθ (U) ≈ 60° at merely 15 V amplitude of AC voltage indicating a potential dielectric for practical low voltage electrowetting applications. A proof of concept confirms electrowetting based rapid mixing of a fluorescent dye in aqueous glycerol solution for 15 V AC signal.

Modified angle's classification for primary dentition

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Kaushik Narendra Chandranee

2017-01-01

Full Text Available Aim: This study aims to propose a modification of Angle's classification for primary dentition and to assess its applicability in children from Central India, Nagpur. Methods: Modification in Angle's classification has been proposed for application in primary dentition. Small roman numbers i/ii/iii are used for primary dentition notation to represent Angle's Class I/II/III molar relationships as in permanent dentition, respectively. To assess applicability of modified Angle's classification a cross-sectional preschool 2000 children population from central India; 3–6 years of age residing in Nagpur metropolitan city of Maharashtra state were selected randomly as per the inclusion and exclusion criteria. Results: Majority 93.35% children were found to have bilateral Class i followed by 2.5% bilateral Class ii and 0.2% bilateral half cusp Class iii molar relationships as per the modified Angle's classification for primary dentition. About 3.75% children had various combinations of Class ii relationships and 0.2% children were having Class iii subdivision relationship. Conclusions: Modification of Angle's classification for application in primary dentition has been proposed. A cross-sectional investigation using new classification revealed various 6.25% Class ii and 0.4% Class iii molar relationships cases in preschool children population in a metropolitan city of Nagpur. Application of the modified Angle's classification to other population groups is warranted to validate its routine application in clinical pediatric dentistry.

Two Comments on Bond Angles

Science.gov (United States)

Glaister, P.

1997-09-01

Tetrahedral Bond Angle from Elementary Trigonometry The alternative approach of using the scalar (or dot) product of vectors enables the determination of the bond angle in a tetrahedral molecule in a simple way. There is, of course, an even more straightforward derivation suitable for students who are unfamiliar with vectors, or products thereof, but who do know some elementary trigonometry. The starting point is the figure showing triangle OAB. The point O is the center of a cube, and A and B are at opposite corners of a face of that cube in which fits a regular tetrahedron. The required bond angle alpha = AÔB; and using Pythagoras' theorem, AB = 2(square root 2) is the diagonal of a face of the cube. Hence from right-angled triangle OEB, tan(alpha/2) = (square root 2) and therefore alpha = 2tan-1(square root 2) is approx. 109° 28' (see Fig. 1).

Electronic Transitions in Conformationally Controlled Tetrasilanes with a Wide Range of SiSiSiSi Dihedral Angles

Czech Academy of Sciences Publication Activity Database

Tsuji, H.; Fogarty, H. A.; Ehara, M.; Fukuda, R.; Casher, D. L.; Tamao, K.; Nakatsuji, H.; Michl, Josef

2014-01-01

Roč. 20, č. 30 (2014), s. 9431-9441 ISSN 0947-6539 Institutional support: RVO:61388963 Keywords : conformational effects * electronic spectra * SAC-CI calculations * silicon * UV/Vis spectroscopy Subject RIV: CC - Organic Chemistry Impact factor: 5.731, year: 2014

Using Digital Technology to See Angles from Different Angles. Part 2: Openings and Turns

Science.gov (United States)

Host, Erin; Baynham, Emily; McMaster, Heather

2015-01-01

Ever wondered how to use technology to teach angles? This article follows on from an earlier article published last year, providing a range of ideas for integrating technology and concrete materials with the teaching of angle concepts. The authors also provide a comprehensive list of free online games and learning objects that can be used to teach…

(E-4-[(4-Nitrophenyldiazenyl]phenyl anthracene-9-carboxylate

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François Léonard

2008-12-01

Full Text Available In the title compound, C27H17N3O4, the azo group displays a trans conformation and the dihedral angles between the central benzene ring and the pendant anthracene and nitrobenzene rings are 82.94 (7 and 7.30 (9°, respectively. In the crystal structure, weak C—H...O hydrogen bonds, likely associated with a dipole moment present on the molecule, help to consolidate the packing.

2,3-Dibromo-1-(4-chlorophenyl-3-(5-nitro-2-furylpropan-1-one

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Balakrishna Kalluraya

2010-12-01

Full Text Available In the title compound, C13H8Br2ClNO4, the linking –CHBr–CHBr– fragment is disordered over two orientations with refined site occupancies of 0.512 (11 and 0.488 (11. The dihedral angle between the furan ring and the phenyl ring is 21.86 (16°. In the crystal, the molecules are linked into [011] chains by intermolecular C—H...O hydrogen bonds.

(E-5,6-Dimethoxy-2-(pyridin-4-ylmethylidene-2,3-dihydro-1H-inden-1-one

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Mohamed Ashraf Ali

2010-11-01

Full Text Available The molecule of the title compound, C17H15NO3, is slightly twisted, with a dihedral angle of 12.12 (3° between the dihydroindenone group and the pyridine ring. In the crystal, molecules are connected into layers parallel to the ab plane via intermolecular C—H...O hydrogen bonds. Weak π–π [centroid–centroid distance = 3.5680 (6 Å] interactions are also observed.

Indole-3-thiouronium nitrate

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Martin Lutz

2008-01-01

Full Text Available In the title compound, C9H10N3S+·NO3−, the indole ring system and the thiouronium group are nearly perpendicular, with a dihedral angle of 88.62 (6°. Hydrogen bonding generates two-dimensional networks which are linked to each other via π stacking interactions of the indole groups [average inter-planar ring–ring distance of 3.449 (2 Å].

3-(2-Fluorophenylsulfinyl-2,5,7-trimethyl-1-benzofuran

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Hong Dae Choi

2013-06-01

Full Text Available In the title compound, C17H15FO2S, the benzofuran ring system, being essentially planar, with an r.m.s. deviation from the least-squares plane of 0.009 (2 Å, makes a dihedral angle of 79.02 (5° with the plane of the 2-fluorophenyl group. In the crystal, molecules are linked by pairs of weak C—H...O hydrogen bonds into centrosymmetric dimers.

N,N-Diethyl-4-[(E-(pyridin-3-yldiazenyl]aniline

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Tatiana V. Timofeeva

2013-08-01

Full Text Available The molecule of the title compound, C15H18N4, adopts a trans conformation with respect to the diazo N=N bond. The dihedral angle between the benzene and pyridine rings in the molecule is 8.03 (5°. In the crystal, a weak C—H...π interaction arranges the molecules into a corrugated ribbon, with an antiparallel orientation of neighboring molecules propagating in the [100] direction.

Crystal structure of 3-methyl-1-phenyl-5-(1H-pyrrol-1-yl-1H-pyrazole-4-carbaldehyde

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Joel T. Mague

2014-10-01

Full Text Available In the title compound, C15H13N3O, the pyrrolyl and phenyl rings make dihedral angles of 58.99 (5 and 34.95 (5°, respectively, with the central pyrazole ring. In the crystal, weak, pairwise C—H...O interactions across centers of symmetry form dimers, which are further associated into corrugated sheets running approximately parallel to (100 via weak C—H...N interactions.

Crystal structure of bromidobis(naphthalen-1-ylantimony(III

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Omar bin Shawkataly

2014-10-01

Full Text Available In the title compound, [SbBr(C10H72], the SbIII atom has a distorted trigonal–pyramidal coordination geometry and the planes of the two naphthalene ring systems make a dihedral angle of 80.26 (18°. An intramolecular C—H...Br hydrogen bond forms an S(5 ring motif. In the crystal, weak C—H...Br interactions link the molecules into helical chains along the b-axis direction.

N-Cyclohexyl-N-ethylbenzenesulfonamide

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Islam Ullah Khan

2009-11-01

Full Text Available The title compound, C14H21NO2S, synthesized by N-methylation of cyclohexylamine sulfonamide with ethyl iodide is of interest as a precursor to biologically active sulfur-containing heterocyclic compounds. There are two independent molecules in the asymmetric unit. The dihedral angles between the mean planes of the phenyl ring and the cyclohexyl ring are 40.29 (11 and 37.91 (13° in the two molecules.

1-Propyl-1H-indole-2,3-dione

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Fatima Zahrae Qachchachi

2016-04-01

Full Text Available In the title compound, C11H11NO2, the 1H-indole-2,3-dione unit is essentially planar, with an r.m.s. deviation of 0.0387 (13 Å. This plane makes a dihedral angle of 72.19 (17° with the plane of the propyl substituent. In the crystal, chains propagating along the b axis are formed through C—H...O hydrogen bonds.

3-Methyl-1-(prop-2-en-1-ylquinoxalin-2(1H-one

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Youssef Ramli

2010-07-01

Full Text Available In the molecule of the title compound, C12H12N2O, the quinoxaline ring is planar with an r.m.s. deviation of 0.007 (15 Å. The dihedral angle between the quinoxaline and propenyl planes is 82.1 (2°. The crystal packing is stabilized by offset π–π stacking between the quinoxaline rings [centroid–centroid distance = 3.8832 (9 Å].

N-(4,5-Diazafluoren-9-ylideneaniline

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Hui Cang

2008-07-01

Full Text Available In the molecule of the title compound, C17H11N3, the 4,5-diazafluorenylidene unit is nearly planar and is oriented with respect to the phenyl ring at a dihedral angle of 75.75 (3°. In the crystal structure, the molecules are aligned in the [100] direction in such a way that neighbouring 4,5-diazafluorenylidene planes face each other in an antiparallel fashion.

8-Bromo-2-methylquinoline

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Lin-Tao Yang

2009-07-01

Full Text Available In the crystal structure of the title compound, C10H8BrN, the dihedral angle between the two six-membered rings of the quinoline system is 0.49 (16°. The molecules are packed in a face-to-face arrangement fashion, with a centroid–centroid distance of 3.76 Å between the benzene and pyridine rings of adjacent molecules. No hydrogen bonding is found in the crystal structure.

3-[(E-(2,4-Dichloropbenzylideneamino]benzoic acid

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Adnan Ashraf

2011-01-01

Full Text Available In the crystal of the title compound, C14H9Cl2NO2, inversion-related dimers with R22(8 ring motifs are formed by intermolecular O—H...O hydrogen bonding. The 3-aminobenzoic acid group and the 2,4-dichlobenzaldehyde moiety subtend a dihedral angle of 55.10 (2°. The H atom of the carboxyl group is disordered over two sites with equal occupancies.

Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

OpenAIRE

Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

2011-01-01

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a prot...

Ethyl 2-[(5Z-5-(4-methoxybenzylidene-2,4-dioxo-1,3-thiazolidin-3-yl]acetate

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Hamza Tachallait

2016-07-01

Full Text Available In the title compound, C15H15NO5S, the benzene and heterocyclic rings are close to being coplanar [dihedral angle = 1.49 (6°]. In the crystal, pairwise C—H...O hydrogen bonds form dimers, which are arranged into `stair-step' rows by way of C=O–π interactions between a carbonyl group and the benzene ring [O...π = 3.3837 (12 Å].

2-{[(2-Methoxynaphthalen-1-ylmethyl]amino}phenol

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Sara Mahdjoub

2016-07-01

Full Text Available The asymmetric unit of the title compound, C18H17NO2, contains two independent molecules (A and B. The dihedral angle between the naphthalene ring system and the benzene ring is 74.67 (10° in molecule A and 78.81 (9° in molecule B. In the crystal, molecules are linked by a series of C—H...π interactions, forming sheets parallel to the ab plane.

4-Allyl-6-bromo-2-phenyl-4H-imidazo[4,5-b]pyridine monohydrate

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Younès Ouzidan

2010-08-01

Full Text Available In the molecule of the title compound, C15H12BrN3·H2O, the phenyl ring is coplanar with the imidazopyridine ring system [dihedral angle = 0.4 (1°]. The water molecule is disordered over two positions with occupancies of 0.58 (1 and 0.42 (1, and it is linked to the main molecule via an O—H...N hydrogen bond.